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Vijay K. Garg University of Toledo, Toledo, Ohio Low-Pressure Turbine Separation Control— Comparison With Experimental Data NASA/CR—2002-211689 July 2002 GT–2002–30229

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Page 1: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

Vija

y K

. Gar

gU

nive

rsit

y of

Tol

edo,

Tol

edo,

Ohi

o

Low

-Pre

ssur

e Tu

rbin

e Se

para

tion

Con

trol

—C

ompa

riso

n W

ith

Exp

erim

enta

l Dat

a

NA

SA/

CR

—20

02-2

1168

9

July

200

2

GT

–200

2–30

229

Page 2: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

The

NA

SA S

TI P

rogr

am O

ffic

e . .

. in

Pro

file

Sinc

e it

s fo

und

ing,

NA

SA h

as b

een

ded

icat

ed to

the

adva

ncem

ent o

f aer

onau

tics

and

spa

cesc

ienc

e. T

he N

ASA

Sci

enti

fic

and

Tec

hnic

alIn

form

atio

n (S

TI)

Pro

gram

Off

ice

play

s a

key

part

in h

elpi

ng N

ASA

mai

ntai

n th

is im

port

ant r

ole.

The

NA

SA S

TI P

rogr

am O

ffic

e is

ope

rate

d b

yL

angl

ey R

esea

rch

Cen

ter,

the

Lea

d C

ente

r fo

rN

ASA

’s s

cien

tifi

c an

d te

chni

cal i

nfor

mat

ion.

The

NA

SA S

TI P

rogr

am O

ffic

e pr

ovid

es a

cces

s to

the

NA

SA S

TI D

atab

ase,

the

larg

est c

olle

ctio

n of

aero

naut

ical

and

spa

ce s

cien

ce S

TI i

n th

e w

orld

.T

he P

rogr

am O

ffic

e is

als

o N

ASA

’s in

stit

utio

nal

mec

hani

sm fo

r d

isse

min

atin

g th

e re

sult

s of

its

rese

arch

and

dev

elop

men

t act

ivit

ies.

The

se r

esul

tsar

e pu

blis

hed

by

NA

SA in

the

NA

SA S

TI R

epor

tSe

ries

, whi

ch in

clud

es th

e fo

llow

ing

repo

rt ty

pes:

•T

EC

HN

ICA

L PU

BL

ICA

TIO

N. R

epor

ts o

fco

mpl

eted

res

earc

h or

a m

ajor

sig

nifi

cant

phas

e of

res

earc

h th

at p

rese

nt th

e re

sult

s of

NA

SA p

rogr

ams

and

incl

ude

exte

nsiv

e d

ata

or th

eore

tica

l ana

lysi

s. In

clud

es c

ompi

lati

ons

of s

igni

fica

nt s

cien

tifi

c an

d te

chni

cal d

ata

and

info

rmat

ion

dee

med

to b

e of

con

tinu

ing

refe

renc

e va

lue.

NA

SA’s

cou

nter

part

of p

eer-

revi

ewed

form

al p

rofe

ssio

nal p

aper

s bu

tha

s le

ss s

trin

gent

lim

itat

ions

on

man

uscr

ipt

leng

th a

nd e

xten

t of g

raph

ic p

rese

ntat

ions

.

•T

EC

HN

ICA

L M

EM

OR

AN

DU

M. S

cien

tifi

can

d te

chni

cal f

ind

ings

that

are

pre

limin

ary

orof

spe

cial

ized

inte

rest

, e.g

., qu

ick

rele

ase

repo

rts,

wor

king

pap

ers,

and

bib

liogr

aphi

esth

at c

onta

in m

inim

al a

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atio

n. D

oes

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ain

exte

nsiv

e an

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TR

AC

TOR

RE

POR

T. S

cien

tifi

c an

dte

chni

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ings

by

NA

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pons

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ract

ors

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ntee

s.

•C

ON

FER

EN

CE

PU

BL

ICA

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N. C

olle

cted

pape

rs fr

om s

cien

tifi

c an

d te

chni

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conf

eren

ces,

sym

posi

a, s

emin

ars,

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ngs

spon

sore

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r co

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.

•SP

EC

IAL

PUB

LIC

AT

ION

. Sci

enti

fic,

tech

nica

l, or

his

tori

cal i

nfor

mat

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NA

SA p

rogr

ams,

pro

ject

s, a

nd m

issi

ons,

ofte

n co

ncer

ned

wit

h su

bjec

ts h

avin

gsu

bsta

ntia

l pub

lic in

tere

st.

•T

EC

HN

ICA

L T

RA

NSL

AT

ION

. Eng

lish-

lang

uage

tran

slat

ions

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orei

gn s

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tifi

can

d te

chni

cal m

ater

ial p

erti

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to N

ASA

’sm

issi

on.

Spec

ializ

ed s

ervi

ces

that

com

plem

ent t

he S

TI

Prog

ram

Off

ice’

s d

iver

se o

ffer

ings

incl

ude

crea

ting

cus

tom

thes

auri

, bui

ldin

g cu

stom

ized

dat

a ba

ses,

org

aniz

ing

and

pub

lishi

ng r

esea

rch

resu

lts

. . .

even

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vid

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eos.

For

mor

e in

form

atio

n ab

out t

he N

ASA

ST

IPr

ogra

m O

ffic

e, s

ee th

e fo

llow

ing:

•A

cces

s th

e N

ASA

ST

I Pro

gram

Hom

e Pa

geat

htt

p://

ww

w.s

ti.n

asa.

gov

•E

-mai

l you

r qu

esti

on v

ia th

e In

tern

et to

help

@st

i.nas

a.go

v

•Fa

x yo

ur q

uest

ion

to th

e N

ASA

Acc

ess

Hel

p D

esk

at 3

01–6

21–0

134

•Te

leph

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NA

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cces

s H

elp

Des

k at

301–

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0390

•W

rite

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N

ASA

Acc

ess

Hel

p D

esk

N

ASA

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ter

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oSpa

ce In

form

atio

n

712

1 St

and

ard

Dri

ve

Han

over

, MD

210

76

Page 3: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

Vija

y K

. Gar

gU

nive

rsit

y of

Tol

edo,

Tol

edo,

Ohi

o

Low

-Pre

ssur

e Tu

rbin

e Se

para

tion

Con

trol

—C

ompa

riso

n W

ith

Exp

erim

enta

l Dat

a

NA

SA/

CR

—20

02-2

1168

9

July

200

2

Nat

iona

l Aer

onau

tics

and

Spac

e A

dm

inis

trat

ion

Gle

nn R

esea

rch

Cen

ter

Prep

ared

und

er C

ontr

act N

AS3

–001

80 a

nd C

oope

rati

ve A

gree

men

t NC

C3–

926

Prep

ared

for

the

Turb

o E

xpo

2002

cosp

onso

red

by

the

Am

eric

an S

ocie

ty o

f Mec

hani

cal E

ngin

eers

and

the

Inte

rnat

iona

l Gas

Tur

bine

Inst

itut

eA

mst

erd

am, T

he N

ethe

rlan

ds,

June

3–6

, 200

2

GT

–200

2–30

229

Page 4: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

Ack

now

led

gmen

ts

The

aut

hor

wis

hes

to th

ank

Dr.

Ray

mon

d G

augl

er, C

hief

, Tur

bine

Bra

nch,

at t

he N

ASA

Gle

nn R

esea

rch

Cen

ter

for

his

supp

ort o

f thi

s w

ork.

Hel

p fr

om D

r. R

icha

rd R

ivir

of t

he A

ir F

orce

Res

earc

h L

abor

ator

y an

d M

ajor

Jeff

rey

Bon

sof

the

Air

For

ce In

stit

ute

of T

echn

olog

y re

gard

ing

the

expe

rim

enta

l dat

a is

als

o gr

atef

ully

ack

now

led

ged

.

Ava

ilabl

e fr

om

NA

SA C

ente

r fo

r A

eros

pace

Info

rmat

ion

7121

Sta

ndar

d D

rive

Han

over

, MD

210

76

Nat

iona

l Tec

hnic

al In

form

atio

n Se

rvic

e52

85 P

ort R

oyal

Roa

dSp

ring

fiel

d, V

A 2

2100

Thi

s re

port

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tain

s pr

elim

inar

yfi

ndin

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ubje

ct to

rev

isio

n as

anal

ysis

pro

ceed

s.

Ava

ilabl

e el

ectr

onic

ally

at h

ttp:

//

gltr

s.gr

c.na

sa.g

ov/

GLT

RS

Trad

e na

mes

or

man

ufac

ture

rs’ n

ames

are

use

d in

this

rep

ort f

orid

enti

fica

tion

onl

y. T

his

usag

e d

oes

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onst

itut

e an

off

icia

len

dor

sem

ent,

eith

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xpre

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, by

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cs a

nd S

pace

Ad

min

istr

atio

n.

Page 5: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

LO

W-P

RE

SS

UR

ET

UR

BIN

ES

EP

AR

AT

ION

CO

NT

RO

L-

CO

MP

AR

ISO

NW

ITH

EX

PE

RIM

EN

TA

LD

AT

A

AB

STR

AC

T

The

pres

ent

wor

kde

tails

aco

mpu

tatio

nals

tudy

,usi

ngth

eG

lenn

-H

Tco

de,

that

anal

yzes

the

use

ofvo

rtex

gene

rato

rje

ts(V

GJs

)to

cont

rol

sepa

ratio

non

alo

w-p

ress

ure

turb

ine

(LPT

)bl

ade

atlo

wR

eyno

lds

num

bers

.T

heco

mpu

tatio

nal

resu

ltsar

eal

soco

mpa

red

with

the

expe

rim

enta

lda

taof

Bon

set

al.

[1]

for

stea

dyV

GJs

.It

isfo

und

that

the

code

dete

rmin

esth

epr

oper

loca

tion

ofth

ese

para

tion

poin

ton

the

suct

ion

surf

ace

ofth

eba

selin

ebl

ade

(with

out

any

VG

J)fo

rR

eyno

lds

num

bers

of50

,000

orle

ss.

Als

o,th

eco

defi

nds

that

the

sepa

rate

dre

gion

onth

esu

ctio

nsu

rfac

eof

the

blad

eva

nish

esw

ithth

eus

eof

VG

Js.

How

ever

,th

ese

para

ted

regi

onan

dth

ew

ake

char

acte

rist

ics

are

not

wel

lpr

edic

ted.

The

wak

ew

idth

isge

nera

llyov

er-p

redi

cted

whi

leth

ew

ake

dept

his

unde

r-pr

edic

ted.

NO

ME

NC

LA

TU

RE

Bje

tbl

owin

gra

tio=

(ρu)

jet/(

ρu) lo

cal

Cp

blad

epr

essu

reco

effi

cien

t=

(po,

in-

p s)/

0.5(

ρu2 ) in

Cx

axia

lch

ord

ofth

ebl

ade

din

ject

ion

hole

diam

eter

ktu

rbul

ence

kine

ticen

ergy

turb

ulen

cele

ngth

scal

ep

pres

sure

PrPr

andt

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ein

let

Rey

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r=

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) inT

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ulen

cein

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stre

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ance

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tes

=ρy

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αth

erm

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ffus

ivity

∆ydi

stan

ce(f

rom

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l)of

the

firs

tpo

int

off

the

wal

turb

ulen

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ssip

atio

nra

teγ

wak

elo

ssco

effi

cien

t=

(po,

in-

p o,e

x)/(

p o,in

-p s

,in)

µdy

nam

icvi

scos

ityρ

dens

ityτ

shea

rst

ress

ωsp

ecif

ictu

rbul

ence

diss

ipat

ion

rate

=ε/

k

Subs

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ts

efef

fect

ive

valu

eex

valu

eat

casc

ade

exit

inva

lue

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ein

let

jet

vort

exge

nera

tor

jet

cond

ition

sla

min

arva

lue

loca

llo

cal

blad

em

id-c

hann

elco

nditi

ons

ost

agna

tion

valu

es

stat

icva

lue

ttu

rbul

ent

valu

ew

valu

eat

the

wal

l

INT

RO

DU

CT

ION

For

the

flow

over

anai

rfoi

l,th

ere

isan

adve

rse

pres

sure

grad

ient

regi

onov

era

larg

epa

rtof

the

suct

ion

surf

ace.

Thi

sca

nca

use

the

flow

tose

para

teon

the

suct

ion

surf

ace,

espe

cial

lyat

low

Rey

nold

snu

mbe

rs,

inw

hich

case

the

boun

dary

laye

rov

erth

ebl

ade

may

bela

min

ar.

Itis

wel

lkn

own

that

ala

min

arbo

unda

ryla

yer

can

with

stan

don

lya

min

orad

vers

epr

essu

regr

adie

ntbe

fore

sepa

ratio

nw

hile

atu

rbul

entb

ound

ary

laye

rca

nw

ithst

and

am

uch

stro

nger

adve

rse

pres

sure

grad

ient

regi

on.

Flow

sepa

ratio

nre

duce

slif

tan

din

crea

ses

drag

.It

isth

usun

desi

rabl

ean

dne

eds

tobe

cont

rolle

d.

Flow

sepa

ratio

nca

nbe

cont

rolle

dby

both

pass

ive

and

activ

ete

chni

ques

.T

hefo

rmer

empl

oys

smal

lvo

rtex

gene

rato

rs(r

ecta

ngul

aror

delta

shap

edw

ingl

ets)

whi

char

eim

bedd

edin

abo

unda

ryla

yer

ahea

dof

alin

eof

flow

sepa

ratio

n[2

].Sp

anw

ise

arra

ysof

vort

exge

nera

tors

are

ofte

npl

aced

alon

ga

win

gup

stre

amof

the

flap

hing

eor

insi

deth

elip

ofa

jet

engi

nein

let

diff

user

.T

helo

ngitu

dina

lvo

rtic

esge

nera

ted

inth

ebo

unda

ryla

yer

incr

ease

cros

s-st

ream

mix

ing

ofst

ream

wis

em

omen

tum

and

supp

ress

orel

imin

ate

sepa

ratio

n.T

hese

fixe

dvo

rtex

gene

rato

rsha

veth

ead

vant

ages

ofsi

mpl

icity

,ru

gged

ness

and

low

cost

.H

owev

er,

they

add

para

sitic

drag

infl

owsi

tuat

ions

whe

rese

para

tion

cont

rol

isno

tne

eded

,e.

g.,

take

-off

and

land

ing.

*NA

SA R

esid

ent R

esea

rch

Ass

ocia

te a

t Gle

nn R

esea

rch

Cen

ter.

Vija

y K

. Gar

g*U

nive

rsity

of

Tole

doTo

ledo

, Ohi

o 43

606

vija

y.ga

rg@

grc.

nasa

.gov

1N

ASA

/CR

—20

02-2

1168

9

Page 6: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

Inon

eof

the

activ

ete

chni

ques

,sm

all

jets

blow

nth

roug

hho

les

inth

eso

lidsu

rfac

eca

nge

nera

telo

ngitu

dina

lst

ream

wis

evo

rtic

esin

abo

unda

ryla

yer.

The

sevo

rtic

esin

crea

secr

oss-

stre

amm

ixin

gof

stre

amw

ise

mom

entu

m.

The

surf

ace

hole

sar

epi

tche

dan

angl

eto

the

surf

ace

(gen

eral

lylo

wpi

tch

angl

eof

30-4

5°),

and

incl

ined

rela

tive

toth

em

ain

flow

dire

ctio

n(s

kew

angl

eva

ryin

gfr

om45

-90°

),m

uch

like

the

com

poun

d-an

gled

hole

son

the

show

er-h

ead

offi

lm-c

oole

dbl

ades

.T

his

met

hod

isca

lled

the

vort

exge

nera

tor

jet

(VG

J)m

etho

d.T

his

met

hod

was

firs

tex

amin

edby

Wal

lis[3

,4]

,an

dby

Wal

lisan

dSt

uart

[5]

prim

arily

for

the

purp

ose

ofde

layi

ngsh

ock-

indu

ced

sepa

ratio

nof

turb

ulen

tbou

ndar

yla

yers

.B

all[

6]em

ploy

edV

GJs

alon

ean

dto

geth

erw

ithfi

xed

gene

rato

rsfo

rst

all

supp

ress

ion

inin

let

diff

user

sof

jet

engi

nes.

Hen

ryan

dPe

arce

y[7

]sh

owcl

earl

yth

ede

velo

pmen

tof

asi

ngle

,do

min

ant

vort

exfo

ra

VG

Jat

high

skew

angl

es.

Itha

sbe

ensh

own

byJo

hnst

onan

dN

ishi

[8]

that

this

vort

exen

ergi

zes

the

sepa

ratin

gbo

unda

ryla

yerb

ybr

ingi

nghi

ghm

omen

tum

free

stre

amfl

uid

dow

nto

the

wal

l.E

xper

imen

tal

data

onth

ebe

nefi

cial

effe

cts

ofV

GJs

are

avai

labl

ein

[9].

The

flow

requ

irem

ents

for

the

jets

inth

eV

GJ

met

hod

isa

very

smal

lfr

actio

nof

the

tota

lje

ten

gine

flow

,and

com

pres

sor

blee

dai

ris

suff

icie

ntto

pow

erth

esy

stem

.T

heje

tsca

nbe

turn

edon

and

off

asde

sire

d.W

ithje

tsof

f,th

ere

isno

para

sitic

drag

.T

hepo

tent

ial

appl

icat

ions

ofth

eV

GJ

met

hod

are

num

erou

sfo

rex

tern

alfl

owov

erai

rcra

ftan

dm

issi

les.

Inte

rnal

flow

sin

diff

user

sca

nal

sobe

impr

oved

and

pres

sure

loss

esre

duce

d.T

heV

GJ

met

hod

can

beus

edw

ithap

prop

riat

efl

owdi

rect

ion

sens

ors

and

afe

edba

ckco

ntro

lsy

stem

tosu

ppre

sssu

rge

and

rota

ting

stal

lin

com

pres

sors

ofje

ten

gine

s.

The

oper

atin

gR

eyno

lds

num

ber

for

the

low

-pre

ssur

etu

rbin

ein

anai

rcra

ftga

stu

rbin

een

gine

can

drop

belo

w25

,000

duri

nghi

ghal

titud

ecr

uise

.A

tsu

chlo

wR

eyno

lds

num

bers

,th

ebo

unda

ryla

yers

onth

eL

PTbl

ades

are

larg

ely

lam

inar

,m

akin

gth

emhi

ghly

susc

eptib

leto

flow

sepa

ratio

nne

arth

eaf

tpo

rtio

nof

the

blad

esu

ctio

nsu

rfac

e,w

ithas

soci

ated

incr

ease

inlo

sses

and

drop

inpe

rfor

man

ce.

Alte

ring

the

blad

esh

ape

toav

oid

this

low

Rey

nold

snu

mbe

rse

para

tion

prob

lem

isno

tfe

asib

lesi

nce

such

am

odif

icat

ion

will

likel

yim

pair

the

engi

neop

erat

ion

athi

gher

(des

ign)

Rey

nold

snu

mbe

rs.

As

such

,an

activ

efl

owco

ntro

lst

rate

gy,

such

asth

eus

eof

VG

Js,

has

been

test

edex

peri

men

tally

atth

eA

irFo

rce

Res

earc

hL

abor

ator

yre

cent

ly[1

,10

].T

his

pape

rai

ms

tous

eth

eG

lenn

-HT

code

inor

der

toan

alyz

eth

eus

eof

VG

Jsat

low

Rey

nold

snu

mbe

rs,

and

toco

mpa

reth

eco

mpu

tatio

nal

pred

ictio

nsw

ithth

eex

peri

men

tal

data

ofB

ons

etal

.[1

].

AN

AL

YSI

S

The

num

eric

alsi

mul

atio

nha

sbe

enpe

rfor

med

usin

gth

eN

ASA

Gle

nnR

esea

rch

Cen

terG

ener

alM

ulti-

Blo

ckN

avie

r-St

okes

Con

vect

ive

Hea

tT

rans

fer

code

,G

lenn

-HT

.B

rief

ly,

the

code

,fo

rmer

lykn

own

asT

RA

F3D

.MB

[11]

,is

anex

plic

it,m

ultig

rid,

cell-

cent

ered

,fi

nite

volu

me

code

with

ak-

ωtu

rbul

ence

mod

elw

ithou

tan

yw

all

func

tions

.T

his

isa

gene

ralp

urpo

sefl

owso

lver

desi

gned

for

sim

ulat

ions

offl

ows

inco

mpl

icat

edge

omet

ries

.T

heN

avie

r-St

okes

equa

tions

ina

rota

ting

Car

tesi

anco

ordi

nate

syst

emar

em

appe

don

toa

gene

ral

body

-fitt

edco

ordi

nate

syst

emus

ing

stan

dard

tech

niqu

es.

The

mul

tista

geR

unge

-K

utta

sche

me

deve

lope

dby

Jam

eson

etal

.[12

]is

used

toad

vanc

eth

efl

owso

lutio

nin

time

from

anin

itial

appr

oxim

atio

nto

the

stea

dyst

ate.

Asp

atia

llyva

ryin

gtim

est

epal

ong

with

aC

FLnu

mbe

rof

4is

used

tosp

eed

conv

erge

nce

toth

est

eady

stat

e.E

igen

valu

e-sc

aled

artif

icia

ldi

ssip

atio

nan

dva

riab

le-c

oeff

icie

ntim

plic

itre

sidu

alsm

ooth

ing

are

used

alon

gw

itha

full-

mul

tigri

dm

etho

d.T

heov

eral

lac

cura

cyof

the

code

isse

cond

orde

r.N

ow

all

func

tions

are

used

,thu

sav

oidi

ngan

ybi

asto

the

com

plex

thre

e-di

men

sion

alfl

owst

ruct

ures

near

the

blad

eor

any

othe

rsu

rfac

e.W

hile

the

Gle

nn-H

Tco

deis

basi

cally

aco

mpr

essi

ble

code

,th

epr

esen

tpr

oble

min

volv

esin

com

pres

sibl

efl

owat

rath

erlo

wR

eyno

lds

num

bers

.T

hus,

ther

ew

ere

som

equ

estio

nsre

gard

ing

the

use

ofG

lenn

-HT

code

insu

cha

situ

atio

n.N

eedl

ess

tosa

y,su

chqu

estio

nsab

out

getti

ngco

nver

ged

solu

tion

from

the

Gle

nn-H

Tco

defo

rsu

cha

case

have

been

put

tore

st.

How

thes

ere

sults

com

pare

with

expe

rim

enta

lda

tais

anot

her

mat

ter.

Whi

leth

eG

lenn

-HT

code

has

the

orig

inal

k-ω

mod

el[1

3],

the

shea

rst

ress

tran

spor

t(S

ST)

mod

elof

Men

ter

[14]

,an

dth

ek-

ωm

odel

ofW

ilcox

[15]

wer

eim

plem

ente

din

itby

Gar

gan

dA

mer

i[1

6].

The

SST

mod

elen

com

pass

esbo

thth

ek-

ωan

dth

ek-

εm

odel

s,w

ithth

eor

igin

alk-

ωm

odel

ofW

ilcox

[13]

activ

ated

inth

ene

ar-w

all

regi

onan

dth

est

anda

rdk-

εm

odel

[17]

activ

ated

inth

eou

ter

wak

ere

gion

and

infr

eesh

ear

laye

rs.

Mor

eove

r,th

ede

fini

tion

ofed

dyvi

scos

ityis

mod

ifie

dto

acco

unt

for

the

tran

spor

tof

the

prin

cipa

ltu

rbul

ent

shea

rst

ress

.T

here

ader

isre

ferr

edto

Men

ter

[14]

for

anel

ucid

atin

gdi

scus

sion

ofth

eSS

Tm

odel

.M

ore

deta

ilson

the

rele

vant

equa

tions

and

thei

rim

plem

enta

tion

are

avai

labl

ein

Gar

gan

dA

mer

i[1

6].

The

SST

mod

elw

asus

edfo

rth

epr

esen

tco

mpu

tatio

ns.

Itis

assu

med

that

the

effe

ctiv

evi

scos

ityfo

rtu

rbul

ent

flow

sca

nbe

wri

tten

as

whe

reth

ela

min

arvi

scos

ityµ

isca

lcul

ated

usin

ga

pow

er-l

awfo

rits

(1)

depe

nden

ceon

tem

pera

ture

[18]

.T

hetu

rbul

ent

visc

osity

µ tis

com

pute

dus

ing

the

SST

mod

el.

The

turb

ulen

tth

erm

aldi

ffus

ivity

isco

mpu

ted

from

whe

rea

cons

tant

valu

eof

0.9

isus

edfo

rth

etu

rbul

entP

rand

tlnu

mbe

r,

(2)

Prt.

Bou

ndar

yC

ondi

tion

s

Att

hem

ain

flow

inle

tbou

ndar

ylo

cate

dat

anax

iald

ista

nce

equa

lto

the

blad

eax

ial

chor

dup

stre

amof

the

blad

ele

adin

ged

ge,

the

tota

lte

mpe

ratu

re,

tota

lpr

essu

re,

whi

rl,

and

mer

idio

nal

flow

angl

ear

esp

ecif

ied,

and

the

upst

ream

-run

ning

Rie

man

nin

vari

ant

base

don

the

tota

lab

solu

teve

loci

tyis

calc

ulat

edat

the

firs

tin

teri

orpo

int

and

extr

apol

ated

toth

ein

let.

The

velo

city

com

pone

nts

are

then

deco

uple

dal

gebr

aica

lly,

and

the

dens

ityis

foun

dfr

omto

tal

tem

pera

ture

,to

tal

pres

sure

and

tota

lve

loci

tyus

ing

anis

entr

opic

rela

tion.

For

the

turb

ulen

cem

odel

,th

eva

lue

ofk

and

ωis

spec

ifie

dus

ing

the

expe

rim

enta

lco

nditi

ons,

nam

ely

whe

reT

u in

isth

ein

tens

ityof

turb

ulen

ceat

the

inle

t(t

aken

tobe

0.01

(3)

aspe

rex

peri

men

tal

data

for

the

PakB

blad

e),

u in

isth

eab

solu

teve

loci

tyat

inle

t,an

dis

the

inte

gral

leng

thsc

ale

repr

esen

ting

the

size

ofth

een

ergy

cont

aini

nged

dies

.T

his

leng

thsc

ale

need

sto

beas

sum

ed,

ifno

tre

port

edas

part

ofth

eex

peri

men

tal

cond

ition

s,as

inth

epr

esen

tca

se.

Itw

asas

sum

edto

be5%

ofth

ebl

ade

axia

lch

ord.

At

the

mai

nfl

owex

itpl

ane

loca

ted

atan

axia

ldi

stan

ceeq

ual

to80

%of

the

blad

eax

ial

chor

ddo

wns

trea

mof

the

blad

etr

ailin

ged

ge,

2N

ASA

/CR

—20

02-2

1168

9

Page 7: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

the

stat

icpr

essu

reis

spec

ifie

dan

dth

ede

nsity

and

velo

city

com

pone

nts

are

extr

apol

ated

from

the

inte

rior

.A

tth

eso

lidsu

rfac

eof

the

blad

e,th

eno

-slip

cond

ition

isen

forc

ed,

and

tem

pera

ture

issp

ecif

ied

aspe

rex

peri

men

tal

data

.T

hebo

unda

ryco

nditi

ons

for

turb

ulen

cequ

antit

ies

onth

ew

alls

are

k=

0,an

d

for

ahy

drau

lical

lysm

ooth

surf

ace.

An

uppe

rlim

itis

impo

sed

onth

e

(4)

valu

eof

ωat

the

wal

l,as

sugg

este

dby

Men

ter

[19]

and

foun

def

fect

ive

byC

him

a[2

0],

The

grid

arou

ndth

ebl

ade

exte

nds

tom

id-w

aybe

twee

ntw

o

(5)

adja

cent

blad

esw

ithpe

riod

icfl

owco

nditi

ons

inte

rms

ofcy

lindr

ical

velo

city

com

pone

nts

set

ona

dum

my

grid

line

outs

ide

this

boun

dary

.Fo

ra

linea

rca

scad

e(w

hich

istr

uefo

rth

eex

peri

men

tal

data

),it

ispo

ssib

leto

cons

ider

only

asl

ice

ofth

ere

alsp

anfo

rco

mpu

tatio

nal

purp

oses

with

ape

riod

icbo

unda

ryco

nditi

onat

both

ends

ofth

eco

mpu

tatio

nal

span

.Fo

rth

eba

sic

blad

ew

ithno

VG

J,th

issl

ice

can

beof

any

reas

onab

lew

idth

,bu

tw

ithV

GJs

,th

ew

idth

ofth

esl

ice

ison

esp

an-w

ise

pitc

hof

the

hole

s.

The

effe

ctof

VG

Jsha

sbe

enin

corp

orat

edin

the

form

ofap

prop

riat

ebo

unda

ryco

nditi

ons

atth

eho

lelo

catio

nson

the

blad

esu

rfac

e.E

ach

hole

exit

inits

true

oval

shap

eis

repr

esen

ted

by22

4co

ntro

lvo

lum

es.

Dif

fere

ntve

loci

tyan

dte

mpe

ratu

repr

ofile

sfo

rth

ein

ject

edfl

uid

can

besp

ecif

ied

atth

eho

leex

its.

For

the

pres

ent

stud

y,po

lyno

mia

ldi

stri

butio

n[2

1]of

velo

city

and

tem

pera

ture

ofth

ein

ject

ant

atth

eho

leex

itw

assp

ecif

ied.

The

inje

ctan

tan

gle

was

take

nto

beth

esa

me

asth

eho

lean

gle.

Tur

bule

ntin

tens

ityat

the

hole

exit

was

assu

med

tobe

1%(s

ame

asfo

rth

efr

eest

ream

),w

hile

the

turb

ulen

cele

ngth

scal

eat

the

hole

exit

was

take

nto

beth

esa

me

asth

eho

ledi

amet

erd.

EX

PE

RIM

EN

TA

LD

ET

AIL

S

Mea

sure

men

tsw

ere

mad

eby

Bon

set

al.[

1]in

anin

duct

ion

win

dtu

nnel

atth

eU

.S.A

irFo

rce

Res

earc

hL

abor

ator

y.T

helin

ear

casc

ade

cons

iste

dof

eigh

t0.8

8m

(34.

5in

)sp

an,0

.18

m(7

in)

axia

lcho

rd(C

x)bl

ades

plus

two

part

ial

blad

een

dwal

ls.

The

blad

esw

ere

fabr

icat

edfr

omm

olde

dpo

lyur

etha

nere

sin.

The

2-D

blad

esh

ape

stud

ied

isth

ePr

att

&W

hitn

ey"P

akB

"re

sear

chde

sign

,w

hich

isa

Mac

hnu

mbe

rsc

aled

vers

ion

ofa

typi

cal

high

lylo

aded

LPT

blad

ede

sign

.T

heca

scad

eha

da

solid

ity(a

xial

chor

dto

blad

esp

acin

g)of

1.13

,an

inle

tfl

owan

gle

of55

°(m

easu

red

from

the

plan

eof

the

casc

ade)

,an

da

desi

gnex

itan

gle

of30

°.B

lade

s4

and

6w

ere

inst

rum

ente

dar

ound

both

pres

sure

and

suct

ion

surf

aces

(in

the

cent

er0.

2m

ofth

eir

span

)w

ithfo

rty

1m

mdi

amet

erst

atic

pres

sure

taps

.U

ncer

tain

ties

inth

epr

essu

rem

easu

rem

ent

tran

slat

edto

aner

ror

of±

0.18

inth

eC

pda

taat

Re

=10

0,00

0[1

].

Bla

de#5

ofth

eca

scad

eha

dth

eac

tive

sepa

ratio

nco

ntro

l.It

was

man

ufac

ture

dw

itha

hollo

wca

vity

runn

ing

the

span

ofth

ebl

ade

and

cove

ring

the

regi

onfr

om40

%to

90%

axia

lch

ord.

Ane

edle

valv

elo

cate

dup

stre

amof

the

feed

port

allo

ws

fine

cont

rol

ofth

em

ass

flow

rate

into

the

blad

eca

vity

.A

irex

haus

tsfr

omth

isva

lve

into

a1.

2cm

diam

eter

capp

edco

pper

tube

runn

ing

the

span

ofth

ebl

ade

insi

deth

eca

vity

.H

oles

of1.

5m

mdi

amet

eran

dsp

aced

ever

y2.

54cm

alon

gth

e

copp

ertu

bepr

oduc

edan

even

dist

ribu

tion

ofai

rfl

owto

the

VG

Js.

The

1m

mdi

amet

er(d

)cy

lindr

ical

VG

Jho

les

wer

edr

illed

from

the

exte

rior

surf

ace

ofth

ebl

ade,

thro

ugh

the

4m

mth

ick

wal

l,an

din

toth

eca

vity

with

a30

°pi

tch

angl

ean

da

90°

skew

angl

e.T

heV

GJ

hole

sha

vea

leng

thof

8dan

dar

esp

aced

ever

y10

dal

ong

the

cent

er0.

46m

ofth

isbl

ade

span

.T

hero

wof

VG

Jsw

aspl

aced

at0.

73C

x.T

his

loca

tion

isw

ithin

the

sepa

rate

dre

gion

onth

eba

selin

e,un

cont

rolle

dbl

ade

ata

Rey

nold

snu

mbe

rof

50,0

00[1

].T

heje

tbl

owin

gra

tio(B

)w

asco

mpu

ted

asth

era

tioof

the

jet

exit

velo

city

toth

elo

cal

free

stre

amve

loci

tyas

calc

ulat

edfr

omth

elo

cal

pres

sure

coef

fici

ent.

Whi

leth

ein

let

Rey

nold

snu

mbe

rw

asva

ried

betw

een

25,0

00an

d10

0,00

0,B

was

take

nas

0,1,

2or

4.

Stan

dard

pito

tan

dho

t-w

ire

prob

esm

ount

edon

ala

rge

Dan

tec

3-ax

istr

aver

selo

cate

dat

opth

etu

nnel

faci

lity

wer

eus

edto

map

a0.

6m×

0.6m

plan

arcr

oss-

sect

ion

ofth

efl

owdo

mai

n.W

ake

velo

city

prof

iles

wer

em

easu

red

usin

ga

sing

le4µ

mdi

amet

ertu

ngst

enho

t-w

ire.

Asi

ngle

TSI

sub-

min

iatu

reho

t-fi

lmpr

obe

was

used

for

boun

dary

laye

rpr

ofile

mea

sure

men

ts.

The

hot-

film

sens

ordi

amet

erw

as25

µman

dth

ese

nsin

gel

emen

tlen

gth

was

0.25

mm

.T

heer

ror

inth

eho

t-w

ire

and

film

prob

esw

asw

ithin

±2%

atfl

owra

tes

ofin

tere

st.

Mor

ede

tails

are

avai

labl

ein

[1].

CO

MP

UT

AT

ION

AL

DE

TA

ILS

The

com

puta

tiona

lsp

anex

tend

edov

era

part

ofth

ebl

ade

span

with

ape

riod

icbo

unda

ryco

nditi

onat

both

ends

.In

the

axia

ldir

ectio

n,th

eco

mpu

tatio

nal

dom

ain

exte

nded

from

the

inle

tpl

ane

loca

ted

one

axia

lcho

rdup

stre

amof

the

blad

ele

adin

ged

geto

the

exit

plan

elo

cate

d80

%of

the

axia

lcho

rddo

wns

trea

mof

the

blad

etr

ailin

ged

ge.

Aro

und

the

blad

e,th

egr

idex

tend

sto

mid

-way

betw

een

two

adja

cent

blad

esw

ithpe

riod

icbo

unda

ryco

nditi

ons.

Figu

re1

show

sa

span

wis

ese

ctio

nof

the

mul

ti-bl

ock

visc

ous

grid

arou

ndth

ebl

ade.

The

visc

ous

grid

isob

tain

edfr

oman

invi

scid

grid

bycl

uste

ring

the

grid

near

all

the

solid

wal

ls(b

lade

here

).T

hecl

uste

ring

isdo

nein

such

aw

ayas

toen

sure

that

inth

evi

scou

sgr

id,

the

dist

ance

ofan

yce

llce

nter

adja

cent

toa

solid

wal

l,m

easu

red

inw

all

units

(y+ ),

isle

ssth

anha

lffo

rth

eca

ses

stud

ied

here

,fo

llow

ing

Boy

lean

dG

iel

[22]

.T

hein

visc

idgr

idw

asge

nera

ted

usin

gth

eco

mm

erci

alco

deG

ridP

ro/a

z300

0[2

3].

For

com

puta

tiona

lac

cura

cyth

era

tioof

two

adja

cent

grid

size

sin

any

dire

ctio

nw

aske

ptw

ithin

0.8-

1.25

.A

sca

nbe

obse

rved

from

Fig.

1,th

egr

idqu

ality

isve

rygo

odes

peci

ally

near

the

blad

esu

rfac

e.Fi

gure

1al

sosh

ows

the

grid

over

the

blad

esp

anne

aran

dw

ithin

the

inje

ctio

nho

leex

its.

Initi

ally

,the

grid

for

the

blad

ew

ithin

ject

ion

hole

sco

nsis

tsof

136

bloc

ksbu

tbe

fore

the

solv

eris

used

,it

can

bem

erge

din

toju

st10

bloc

ksus

ing

the

Met

hod

ofW

eake

stD

esce

nt[2

4].

The

fina

lvi

scou

sgr

idco

nsis

tsof

1601

28ce

lls,f

orm

edby

clus

teri

ngne

arth

ebl

ade

from

anin

visc

idgr

idw

ith92

928

cells

.T

here

are

224

cells

with

inth

eho

leex

iton

the

blad

esu

rfac

e.T

hein

visc

idgr

idha

s14

4ce

llsar

ound

the

blad

e(f

orth

eO

-gri

dar

ound

the

blad

e),

28ce

llsin

the

blad

e-to

-bla

dedi

rect

ion

from

the

blad

eto

the

peri

odic

boun

dary

in-b

etw

een

the

two

blad

es,a

nd24

inth

esp

anw

ise

dire

ctio

n.A

fter

clus

teri

ng,t

henu

mbe

rof

cells

inth

ebl

ade-

to-b

lade

dire

ctio

nin

crea

ses

to48

.T

wo

mor

egr

ids

wer

ege

nera

ted

for

agr

id-i

ndep

ende

nce

stud

y.O

nein

visc

idgr

idha

d1.

5tim

esth

enu

mbe

rof

cells

inea

chdi

rect

ion

asco

mpa

red

toth

eba

sic

grid

desc

ribe

dab

ove.

For

the

seco

ndgr

id,t

heba

sic

invi

scid

grid

was

clus

tere

dne

arth

ebl

ade

with

agr

idsp

acin

gha

lfof

that

for

the

basi

cvi

scou

sgr

id.

All

thes

eva

riat

ions

ofth

eba

sic

grid

yiel

ded

near

lyth

esa

me

valu

esfo

rth

esk

infr

ictio

nco

effi

cien

ton

the

entir

ebl

ade

surf

ace

asth

eba

sic

grid

;an

yva

riat

ions

wer

ew

ithin

±2%

.T

here

sults

pres

ente

dhe

reco

rres

pond

toth

eba

sic

grid

show

nin

Fig.

1.

3N

ASA

/CR

—20

02-2

1168

9

Page 8: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

Com

puta

tions

wer

eru

non

the

16-p

roce

ssor

C90

supe

rcom

pute

rat

NA

SAA

mes

Res

earc

hC

ente

r.T

heco

dere

quir

esab

out

26m

illio

nw

ords

ofst

orag

ew

ithal

lblo

cks

inm

emor

yfo

rth

eca

sew

ithin

ject

ion,

and

take

sab

out

7s

per

itera

tion

for

two

leve

lsof

mul

ti-gr

id.

Aca

sere

quir

esab

out

4000

itera

tions

toco

nver

gefo

ra

case

with

inje

ctio

n.T

his

unus

ually

larg

enu

mbe

rof

itera

tions

for

conv

erge

nce

isdu

eto

the

com

puta

tion

ofin

com

pres

sibl

efl

owat

low

Rey

nold

snu

mbe

rs.

Rec

allin

gth

atth

eG

lenn

-HT

code

ises

sent

ially

aco

mpr

essi

ble

code

,th

eco

dew

asin

itial

lyru

nto

near

-con

verg

ence

for

one

case

with

and

with

out

inje

ctio

nfo

ran

exit

Mac

hnu

mbe

rof

0.6.

The

exit

Mac

hnu

mbe

rw

asth

ensu

bseq

uent

lyre

duce

din

step

sof

0.1

toa

fina

lva

lue

of0.

2,w

hich

ises

sent

ially

anin

com

pres

sibl

efl

owco

nditi

on.

Thi

sob

viat

edth

eus

eof

any

low

Mac

hnu

mbe

rpr

econ

ditio

ning

.Fo

rsu

bseq

uent

case

s,re

sults

for

this

case

serv

edas

the

star

ting

poin

t.

RE

SUL

TS

and

DIS

CU

SSIO

N

Seve

ral

expe

rim

enta

lca

ses

for

the

PakB

blad

e,av

aila

ble

in[1

],w

ere

anal

yzed

for

com

pari

son.

The

seca

ses

cove

rth

ree

inle

tRey

nold

snu

mbe

rva

lues

,25

000,

5000

0an

d10

0000

for

afr

eest

ream

turb

ulen

tin

tens

ityof

1%.

Mos

tof

the

data

in[1

]ar

efo

rT

u=

1%.

Val

ues

ofB

for

whi

chco

mpu

tatio

nsw

ere

done

are

0,1

and

2.Fi

gure

2sh

ows

the

com

pute

dsh

ear

stre

sson

the

basi

cbl

ade

surf

ace,

with

outa

nyV

GJ,

for

thre

eva

lues

ofth

ein

let

Rey

nold

snu

mbe

r.In

this

figu

re,t

heze

rosh

ear

stre

sslin

eis

show

nfo

rre

fere

nce.

Cle

arly

,th

esh

ear

stre

ssis

nega

tive

beyo

ndth

ese

para

tion

poin

ton

the

suct

ion

surf

ace

ofth

ebl

ade.

The

sepa

ratio

npo

int

onth

esu

ctio

nsu

rfac

e,co

rres

pond

ing

toτ w

=0,

islit

tleaf

fect

edby

the

Rey

nold

snu

mbe

r;it

isat

0.71

Cx

for

Re

=50

,000

and

100,

000,

but

at0.

73C

xfo

rR

e=

25,0

00.

The

reap

pear

sto

bea

smal

lre

gion

onth

epr

essu

resu

rfac

eas

wel

lth

atha

sse

para

ted

flow

for

Rey

nold

snu

mbe

rs≥

50,0

00.

The

smal

lse

para

ted

regi

onon

the

pres

sure

surf

ace

isov

er0.

22≤

x/C

x≤

0.25

for

Re

=50

,000

,an

dov

er0.

18≤

x/C

x≤

0.29

for

Re

=10

0,00

0.T

here

isno

sepa

rate

dre

gion

over

the

pres

sure

surf

ace

for

Re

=25

,000

.T

helo

catio

nof

sepa

ratio

npo

int

onth

esu

ctio

nsu

rfac

em

atch

esve

ryw

ell

with

the

expe

rim

enta

lda

ta[2

5]fo

rR

eyno

lds

num

bers

of50

,000

orle

ss.

Bon

set

al.

[1]

give

noin

dica

tion

whe

ther

they

obse

rved

any

sepa

rate

dre

gion

over

the

pres

sure

surf

ace.

We

may

note

that

the

boun

dary

laye

rov

erth

een

tire

blad

eis

lam

inar

,as

evid

ence

din

Fig.

3.T

his

figu

resh

ows

the

dim

ensi

onle

sstu

rbul

ent

visc

osity

,µt,

with

ina

narr

owra

nge

from

0to

1.0

inth

efl

owfi

eld

for

Re

=50

,000

and

B=

0an

d1.

Not

ing

that

the

dim

ensi

onle

ssla

min

arvi

scos

ity,

µ,

isne

arly

unity

(dim

ensi

onle

sslo

cal

tem

pera

ture

isne

arun

ity),

itis

clea

rth

atth

eef

fect

ive

visc

osity

with

inth

een

tire

boun

dary

laye

rov

erth

ebl

ade

surf

ace

ises

sent

ially

lam

inar

.W

em

ayno

teth

epr

esen

ceof

sepa

ratio

non

the

suct

ion

surf

ace

inFi

g.3(

a),

whi

lew

ithth

eV

GJs

turn

edon

,th

efl

owge

tsat

tach

ed(c

f.Fi

g.3(

b)).

Sim

ilar

resu

ltsw

ere

obta

ined

for

Re

of25

,000

and

100,

000.

Figu

re4

show

sth

eve

loci

tyve

ctor

s,co

lore

dby

stat

icpr

essu

re,i

nth

efl

owfi

eld

arou

ndth

ebl

ade

for

inle

tR

eyno

lds

num

ber

of50

,000

,an

dfo

rB

=0

and

1.T

heth

ick

sepa

rate

dre

gion

,with

reve

rse

flow

,is

clea

rly

visi

ble

inFi

g.4(

a)fo

rth

eun

cont

rolle

dbl

ade,

whi

leth

ere

isal

mos

tno

sepa

ratio

non

the

suct

ion

surf

ace

for

the

cont

rolle

dbl

ade

(Fig

.4(

b))

with

B=

1.O

nth

epr

essu

resu

rfac

e,th

eve

loci

typr

ofile

sap

pear

tobe

clos

eto

sepa

ratio

nov

era

very

smal

lre

gion

,as

disc

usse

dab

ove

rega

rdin

gth

ere

sults

inFi

g.2.

Sim

ilar

resu

ltsw

ere

obta

ined

for

Re

of25

,000

and

100,

000.

Figu

re5

com

pare

sth

epr

esen

tcom

puta

tions

with

the

expe

rim

enta

lda

ta[1

]fo

rth

epr

essu

reco

effi

cien

ton

the

base

line

blad

eat

two

inle

t

Rey

nold

snu

mbe

rsan

dT

u=

1%.

The

com

pari

son

isve

rygo

odon

the

pres

sure

surf

ace

but

not

sogo

odon

the

suct

ion

surf

ace

due

toth

epr

esen

ceof

sepa

ratio

n.W

hile

the

expe

rim

enta

ldat

aex

hibi

tthe

clas

sic

plat

eau

indi

catin

gno

n-re

atta

chin

gla

min

arse

para

tion,

the

anal

ysis

pred

icts

sign

ific

ant

diff

usio

nth

roug

hth

ese

para

tion

regi

on.

Sim

ilar

disc

repa

ncy

was

obse

rved

byB

ons

etal

.[1

]be

twee

nth

eir

expe

rim

enta

lda

taan

dth

e2-

DN

avie

r-St

okes

Van

eB

lade

Inte

ract

ion

(VB

I)co

de.

Figu

re6

com

pare

sth

eco

mpu

ted

boun

dary

laye

rpr

ofile

sov

erth

eba

selin

e(n

oV

GJ)

blad

esu

ctio

nsu

rfac

eat

thre

ech

ordw

ise

loca

tions

with

the

expe

rim

enta

lda

tafr

omB

ons

etal

.[1

]fo

rR

e=

50,0

00an

dT

u=

1%.

At

67%

axia

lch

ord,

the

expe

rim

enta

lpr

ofile

was

note

dby

Bon

set

al.[

1]to

beun

stea

dyin

the

regi

ony

<3m

m.

Tha

tis

why

the

expe

rim

enta

lda

tafa

llin

toa

wid

eba

ndin

the

near

-wal

lre

gion

.A

t73

%an

d79

%ax

ialc

hord

,the

flow

isse

para

ted,

with

the

com

puta

tions

clea

rly

show

ing

reve

rse

flow

.Fo

rth

eex

peri

men

tal

data

,rev

erse

flow

dire

ctio

nco

uld

not

bere

solv

ed[1

]si

nce

asi

ngle

hot-

film

prob

ew

asus

ed.

How

ever

,se

para

tesm

oke

visu

aliz

atio

ndi

dco

nfir

mth

atfl

owre

vers

alw

aspr

esen

tin

side

the

sepa

ratio

nbu

bble

atth

e73

%ax

ial

chor

dm

easu

rem

ent

stat

ion.

The

com

pari

son

betw

een

the

com

pute

dan

dex

peri

men

tal

data

isno

tve

rygo

od,

spec

ially

at79

%ax

ial

chor

dlo

catio

n,w

here

the

expe

rim

enta

lda

tash

owm

uch

thic

ker

boun

dary

laye

rco

mpa

red

toth

eco

mpu

tatio

ns.

Thi

sim

plie

sth

atth

ese

para

ted

regi

onis

not

wel

lre

solv

edby

the

com

puta

tions

.

Asi

mila

rco

mpa

riso

nis

show

nin

Fig.

7fo

rin

let

Rey

nold

snu

mbe

r=

100,

000

and

B=

0.C

lear

lyat

this

high

Rey

nold

snu

mbe

r,th

ebo

unda

ryla

yer

isth

inne

rco

mpa

red

toth

atin

Fig.

6.H

owev

er,t

heex

peri

men

tal

data

show

ath

inne

rbo

unda

ryla

yer

com

pare

dto

that

from

the

com

puta

tions

atal

lth

ree

chor

dwis

elo

catio

ns.

Whi

leth

eco

mpu

tatio

nssh

owse

para

ted

(rev

erse

)fl

owat

both

73%

and

79%

axia

lch

ord

loca

tions

,B

ons

etal

.[1

]re

port

that

the

flow

was

clos

eto

sepa

ratio

nat

the

79%

axia

lch

ord

loca

tion

but

atta

ched

atth

e73

%ax

ialc

hord

loca

tion.

Figu

re8

com

pare

sth

eco

mpu

ted

velo

city

prof

iles

inth

ew

ake

at0.

62ax

ial

chor

ddo

wns

trea

mfr

omth

ebl

ade

trai

ling

edge

for

two

inle

tR

eyno

lds

num

bers

agai

nst

the

expe

rim

enta

lda

taof

Bon

set

al.[

1]w

ithno

VG

J.W

hile

the

com

puta

tions

show

little

effe

ctof

Re

onth

ew

ake

wid

than

dre

lativ

ely

smal

leff

ecto

nth

ew

ake

dept

h,th

eex

peri

men

tal

data

show

ala

rger

effe

ctof

Re

onbo

thth

ew

ake

wid

than

dde

pth.

At

Re

=50

,000

,th

eco

mpu

ted

and

expe

rim

enta

lw

ake

wid

ths

mat

chbu

tth

eco

mpu

ted

wak

ede

pth

ison

lyab

out

half

ofth

eex

peri

men

tal

valu

e.A

tR

e=

100,

000,

the

com

pute

dw

ake

dept

hco

mpa

res

wel

lw

ithth

eex

peri

men

tal

valu

ebu

tth

eco

mpu

ted

wak

ew

idth

isab

out

twic

eth

atof

the

expe

rim

enta

lva

lue.

Such

prob

lem

sw

ithco

mpu

ted

wak

esar

ew

ell

know

n,an

dpo

int

toth

ene

edfo

rm

ore

wor

kin

this

area

.M

oreo

ver,

inth

epr

esen

tca

se,

thes

epr

oble

ms

are

augm

ente

dby

the

larg

ese

para

tion

regi

onov

erth

esu

ctio

nsu

rfac

eof

the

blad

e.A

nyun

stea

dyef

fect

sow

ing

toth

efl

owse

para

tion

and

wak

esh

eddi

ngca

nnot

bere

solv

edby

the

stea

dyco

deth

atw

asus

edfo

rth

epr

esen

tco

mpu

tatio

ns.

Figu

re9

show

sa

com

pari

son

betw

een

the

pres

ently

com

pute

dlo

ssco

effi

cien

t,γ,

and

the

expe

rim

enta

lva

lues

prov

ided

byB

ons

etal

.[1

0].

Whi

leth

eex

peri

men

tal

data

show

asu

dden

drop

inlo

ssco

effi

cien

taro

und

Re

=50

,000

,the

com

puta

tions

show

only

agr

adua

lde

crea

sein

the

loss

coef

fici

ent

from

Re

=25

,000

to10

0,00

0.T

his

isag

ain

are

flec

tion

ofth

epo

orw

ake

pred

ictio

nno

ted

abov

e.Fi

gure

10co

mpa

res

the

com

pute

dbo

unda

ryla

yer

prof

iles

over

the

blad

esu

ctio

nsu

rfac

eat

thre

ech

ordw

ise

loca

tions

with

the

expe

rim

enta

lda

tafr

omB

ons

etal

.[1]

for

Re

=50

,000

and

B=

2.B

oth

the

com

puta

tions

and

expe

rim

ent

show

nose

para

tion

(rev

erse

flow

).H

owev

er,

the

4N

ASA

/CR

—20

02-2

1168

9

Page 9: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

expe

rim

enta

lda

tash

owst

eepe

rpr

ofile

sth

anth

eco

mpu

ted

resu

ltsat

all

the

stat

ions

,sim

ilar

toth

ere

sults

inFi

g.7

for

Re

=10

0,00

0an

dno

VG

J.B

ons

etal

.[1

]at

trib

ute

the

doub

ly-i

nfle

cted

(but

atta

ched

)ve

loci

typr

ofile

at79

%ax

ial

chor

dst

atio

nto

the

ultim

ate

pene

trat

ion

dept

hof

the

vort

exje

tsin

toth

efr

eest

ream

.T

heco

mpu

ted

resu

ltsdo

not

show

any

such

anom

aly.

Figu

re11

com

pare

sth

eco

mpu

ted

velo

city

prof

iles

inth

ew

ake

at0.

62ax

ial

chor

ddo

wns

trea

mfr

omth

ebl

ade

trai

ling

edge

for

anin

let

Rey

nold

snu

mbe

rof

50,0

00ag

ains

tth

eex

peri

men

tal

data

ofB

ons

etal

.[1

]w

ithan

dw

ithou

tV

GJs

.W

em

ayno

teth

atth

eda

taco

rres

pond

ing

toB

=0

are

also

avai

labl

ein

Fig.

8;th

eyar

ein

clud

edhe

reto

com

pare

with

the

data

for

B≠

0.T

heco

mpu

ted

wak

ew

ithV

GJs

on(B

≠0)

issh

allo

wer

and

som

ewha

tnar

row

erth

anth

atw

ithou

tan

yV

GJ

(B=

0),

ason

ew

ould

expe

ctsi

nce

the

sepa

ratio

nre

gion

vani

shes

whe

nV

GJs

are

on.

How

ever

,th

eef

fect

isno

tso

dram

atic

,sp

ecia

llyfo

rth

ew

ake

wid

th,

asfo

rth

eex

peri

men

tal

data

.E

xper

imen

tally

the

wak

eis

very

narr

oww

hen

the

VG

Jsar

eon

com

pare

dto

the

case

whe

nth

eyar

eno

t.T

hew

ake

dept

hre

cove

ry,

ratio

ofth

ew

ake

dept

hfo

rB

≠0

toth

atfo

rB

=0,

isab

out

the

sam

efo

rbo

thth

eco

mpu

tatio

nal

and

expe

rim

enta

lda

ta.

Als

o,th

ere

islit

tledi

ffer

ence

betw

een

the

prof

iles

corr

espo

ndin

gto

B=

1an

dB

=2

for

both

the

com

puta

tiona

lan

dex

peri

men

tal

data

.

CO

NC

LU

SIO

NS

The

Gle

nn-H

Tco

dew

asus

edto

com

pute

the

flow

over

alo

w-

pres

sure

turb

ine

blad

eat

very

low

Rey

nold

snu

mbe

rsw

ithan

dw

ithou

tth

eus

eof

vort

exge

nera

tor

jets

.T

here

sults

are

com

pare

dw

ithth

eex

peri

men

tal

data

ofB

ons

etal

.[1

]fo

rst

eady

VG

Js.

Itis

foun

dth

atth

eco

dede

term

ines

the

prop

erlo

catio

nof

the

sepa

ratio

npo

int

onth

esu

ctio

nsu

rfac

eof

the

base

line

blad

e(w

ithou

tan

yV

GJ)

for

Rey

nold

snu

mbe

rsof

50,0

00or

less

.A

lso,

the

code

find

sth

atth

ese

para

ted

regi

onon

the

suct

ion

surf

ace

ofth

ebl

ade

vani

shes

with

the

use

ofV

GJs

.H

owev

er,t

hese

para

ted

regi

onan

dth

ew

ake

char

acte

rist

ics

are

not

wel

lpr

edic

ted.

The

wak

ew

idth

isge

nera

llyov

er-p

redi

cted

whi

leth

ew

ake

dept

his

unde

r-pr

edic

ted.

Thu

s,th

ere

isa

need

toim

prov

eth

epr

edic

tion

ofw

ake

char

acte

rist

ics,

espe

cial

lyin

situ

atio

nsw

here

larg

ese

para

ted

regi

ons

may

exis

tup

stre

amof

the

wak

e,as

inth

epr

esen

tca

se.

For

reso

lutio

nof

the

unst

eady

effe

cts

due

tofl

owse

para

tion

and

wak

esh

eddi

ng,

use

ofan

unst

eady

code

isre

com

men

ded.

RE

FE

RE

NC

ES

1.B

ons,

J.P.

,So

nder

gaar

d,R

.an

dR

ivir

,R

.B.,

1999

,C

ontr

olof

Low

-Pre

ssur

eT

urbi

neSe

para

tion

Usi

ngV

orte

xG

ener

ator

Jets

,A

IAA

Pape

r99

-036

7.2.

Pear

cey,

H.H

.,19

61,

Shoc

kIn

duce

dSe

para

tion

and

itsPr

even

tion,

Bou

ndar

yL

ayer

&F

low

Con

trol

,vo

l.2,

(Ed.

)G

.V.

Lac

hman

n,Pe

rgam

on,

NY

,pp

.11

70-1

344.

3.W

allis

,R

.A.,

1952

,T

heU

seof

Air

Jets

for

Bou

ndar

yL

ayer

Con

trol

,A

erod

ynam

ics

Res

earc

hL

abor

ator

ies,

Aus

tral

ia,

Aer

oN

ote

110

(N-3

4736

).4.

Wal

lis,

R.A

.,19

60,

APr

elim

inar

yN

ote

ona

Mod

ifie

dT

ype

ofA

irJe

tfo

rB

ound

ary

Lay

erC

ontr

ol,

Aer

onau

tical

Res

earc

hC

ounc

il,A

ustr

alia

,C

urre

ntPa

per

No.

513.

5.W

allis

,R

.A.

and

Stua

rt,

C.M

.,19

58,

On

the

Con

trol

ofSh

ock-

Indu

ced

Bou

ndar

y-L

ayer

Sepa

ratio

nw

ithD

iscr

ete

Jets

,A

eron

autic

alR

esea

rch

Cou

ncil,

Aus

tral

ia,C

urre

ntPa

per

No.

595

(N63

-101

38).

6.B

all,

W.H

.,19

84,

Tes

tsof

Wal

lB

low

ing

Con

cept

sfo

rD

iffu

ser

Bou

ndar

yL

ayer

Con

trol

,A

IAA

Pape

r84

-127

6.7.

Hen

ry,

F.S.

and

Pear

cey,

H.H

.,19

94,

Num

eric

alM

odel

ofB

ound

ary

Lay

erC

ontr

olU

sing

Air

-Jet

Gen

erat

edV

ortic

es,A

IAA

J.,

vol.

32,

pp.

2415

-242

5.8.

John

ston

,J.P

.and

Nis

hi,M

.,19

90,V

orte

xG

ener

ator

Jets

-M

eans

for

Flow

Sepa

ratio

nC

ontr

ol,

AIA

AJ.

,vo

l.28

,pp

.98

9-99

4.9.

Com

pton

,D

.A.

and

John

ston

,J.

P.,

1992

,St

ream

wis

eV

orte

xPr

oduc

tion

byPi

tche

dan

dSk

ewed

Jets

ina

Tur

bule

ntB

ound

ary

Lay

er,

AIA

AJ.

,vo

l.30

,pp

.64

0-64

7.10

.B

ons,

J.P.

,So

nder

gaar

d,R

.an

dR

ivir

,R

.B.,

2001

,T

heFl

uid

Dyn

amic

sof

LPT

Bla

deSe

para

tion

Con

trol

Usi

ngPu

lsed

Jets

,A

SME

Pape

r20

01-G

T-1

90.

11.

Stei

ntho

rsso

n,E

.,A

mer

i,A

.A.

and

Rig

by,

D.L

.,19

97,

TR

AF3

D.M

BA

Mul

ti-B

lock

Flow

Solv

erfo

rT

urbo

mac

hine

ryFl

ows,

AIA

APa

per

97-0

996.

12.

Jam

eson

,A

.,Sc

hmid

t,W

.an

dT

urke

l,E

.,19

81,

Num

eric

alSo

lutio

nsof

the

Eul

erE

quat

ions

byFi

nite

Vol

ume

Met

hods

Usi

ngR

unge

-Kut

taT

ime-

Step

ping

Sche

mes

,A

IAA

Pape

r81

-12

59.

13.

Wilc

ox,

D.C

.,19

88,

Rea

sses

smen

tof

the

Scal

e-D

eter

min

ing

Equ

atio

nfo

rA

dvan

ced

Tur

bule

nce

Mod

els,

AIA

AJ.

,vol

.26,

pp.

1299

-131

0.14

.M

ente

r,F.

R.,

1994

,T

wo-

Equ

atio

nE

ddy-

Vis

cosi

tyT

urbu

lenc

eM

odel

sfo

rE

ngin

eeri

ngA

pplic

atio

ns,A

IAA

J.,v

ol.3

2,pp

.159

8-16

05.

15.

Wilc

ox,

D.C

.,19

98,

Tur

bule

nce

Mod

elin

gfo

rC

FD,

DC

WIn

dust

ries

,2n

dE

dn.

16.

Gar

g,V

.K.

and

Am

eri,

A.A

.,20

01,

Tw

o-E

quat

ion

Tur

bule

nce

Mod

els

for

Pred

ictio

nof

Hea

tT

rans

fer

ona

Tra

nson

icT

urbi

neB

lade

,In

t.J.

Hea

t&

Flu

idF

low

,vo

l.22

,pp

.59

3-60

2.17

.Jo

nes,

W.P

.an

dL

aund

er,

B.E

.,19

73,

The

Cal

cula

tion

ofL

ow-R

eyno

lds-

Num

ber

Phen

omen

aw

itha

Tw

oE

quat

ion

Mod

elof

Tur

bule

nce,

Int.

J.H

eatM

ass

Tra

nsfe

r,vo

l.16

,pp.

1119

-113

0.18

.Sc

hlic

htin

g,H

.,19

79,

Bou

ndar

yL

ayer

The

ory,

McG

raw

-Hill

,N

ewY

ork,

7thed

ition

,pp

.31

2-31

3.19

. M

ente

r,

F.R

., 19

92,

Impr

oved

T

wo-

Equ

atio

n k-

ω

Tur

bule

nce

Mod

els

for

Aer

odyn

amic

Flo

ws,

NA

SA T

M-1

0397

5.20

.C

him

a,R

.V.,

1996

,A

k-ω

Tur

bule

nce

Mod

elfo

rQ

uasi

-Thr

ee-

Dim

ensi

onal

Tur

bom

achi

nery

Flow

s,A

IAA

Pape

r96

-024

8.21

.G

arg,

V.K

.an

dG

augl

er,

R.E

.,19

97,

Eff

ect

ofV

eloc

ityan

dT

empe

ratu

reD

istr

ibut

ion

atth

eH

ole

Exi

ton

Film

Coo

ling

ofT

urbi

neB

lade

s,J.

Tur

bom

achi

nery

,vo

l.11

9,pp

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3-35

1.22

.B

oyle

,R.J

.and

Gie

l,P.

,199

2,T

hree

-Dim

ensi

onal

Nav

ier

Stok

esH

eat

Tra

nsfe

rPr

edic

tions

for

Tur

bine

Bla

deR

ows,

AIA

APa

per

92-3

068.

23.

Prog

ram

Dev

elop

men

tC

orpo

ratio

n,19

97,

"Gri

dPro

TM

/az3

000

-U

ser’

sG

uide

and

Ref

eren

ceM

anua

l,"W

hite

Plai

ns,

NY

.24

.R

igby

,D.L

.,St

eint

hors

son,

E.a

ndC

oiri

er,W

.J.,

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,Aut

omat

icB

lock

Mer

ging

Usi

ngth

eM

etho

dof

Wea

kest

Des

cent

,A

IAA

Pape

r97

-019

7.25

.R

ivir

,R

.B.,

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,pr

ivat

eco

mm

unic

atio

n.

5N

ASA

/CR

—20

02-2

1168

9

Page 10: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

-25

0

25

50

75

00.20.40.60.81.0

Re=100000Re=50000Re=25000

pressure

suction

x/cx

τw

Fig. 2 Computed shear stress on the blade surface at various inlet Reynolds numbers (Tu = 1%; B = 0)

(a)(b)Fig. 3 Dimensionless turbulent viscosity within 0 and 1 in the flow field for Re = 50,000; Tu = 1%. (a) B = 0; (b) B = 1.

Fig. 4 Computed velocity vectors, colored by static pressure, around the blade for Re = 50,000; Tu = 1%. (a) B = 0; (b) B = 1.

(a)(b)

periodicboundary

periodicboundary

periodicboundary

0

1

2

3

4

5

00.20.40.60.81.0

expt, Re=50000expt, Re=100000comp, Re=50000comp, Re=100000

x/cx

Cp

Fig. 5 Comparison of pressure coefficient for baseline blade at two inlet Reynolds numbers and Tu = 1%

Fig. 1 Spanwise section of the multi−block viscous grid around the blade, with detail of grid over the blade span near and within the hole exits

0.9

1.0p/po

6N

ASA

/CR

—20

02-2

1168

9

Page 11: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

0

0.5

1.0

1.5 -0

.20.

20.

61.

0

expt

0.7

9ex

pt 0

.73

expt

0.6

7co

mp

0.79

com

p 0.

73co

mp

0.67

u/m

id-c

hann

el v

eloc

ity

y (cm)

Fig

. 6 C

ompa

rison

of b

ound

ary

laye

r pr

ofile

s of

str

eam

line

velo

city

norm

aliz

ed b

y m

id−c

hann

el v

eloc

ity a

t thr

ee c

hord

wis

e st

atio

ns:

0.67

, 0.7

3 an

d 0.

79 a

xial

cho

rd o

n th

e su

ctio

n si

de.

Re

= 50

,000

; Tu

= 1%

; B =

0

0

0.5

1.0

1.5 -0

.20.

20.

61.

0

expt

0.7

9ex

pt 0

.73

expt

0.6

7co

mp

0.79

com

p 0.

73co

mp

0.67

u/m

id-c

hann

el v

eloc

ity

y (cm)

Fig

. 7 C

ompa

rison

of b

ound

ary

laye

r pr

ofile

s of

str

eam

line

velo

city

norm

aliz

ed b

y m

id−c

hann

el v

eloc

ity a

t thr

ee c

hord

wis

e st

atio

ns:

0.67

, 0.7

3 an

d 0.

79 a

xial

cho

rd o

n th

e su

ctio

n si

de.

Re

= 10

0,00

0; T

u =

1%; B

= 0

0.80

0.85

0.90

0.95

1.00

1.05

3.4

3.8

4.2

expt

, Re=

1000

00co

mp,

Re=

1000

00ex

pt, R

e=50

000

com

p, R

e=50

000

4.4

y/bl

ade

spac

ing

streamwise velocity/mid-channel velocity

Fig.

8 C

ompa

rison

of w

ake

velo

city

pro

file

at 0

.62

axia

l cho

rd d

owns

tream

from

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e tra

iling

edg

e fo

r tw

o in

let R

eyno

lds

num

bers

. Tu

= 1

%

an

d B

= 0

0

0.15

0.30

0.45

0.60

0.75

00.

4x10

50.

8x10

51.

2x10

5

expt

com

p

Re in

loss coefficient

Fig

. 9 C

ompa

rison

of l

oss

coef

ficie

nt v

s. in

let R

eyno

lds

num

ber

for

Tu

= 1%

0

0.5

1.0

1.5

00.

30.

60.

91.

2

expt

0.7

9ex

pt 0

.73

expt

0.6

7co

mp

0.79

com

p 0.

73co

mp

0.67

u/m

id-c

hann

el v

eloc

ity

y (cm)

Fig

. 10

Com

paris

on o

f bou

ndar

y la

yer

prof

iles

of s

trea

mlin

e ve

loci

ty

n

orm

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ed b

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ity a

t thr

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e st

atio

ns:

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and

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al c

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on

the

suct

ion

side

.

R

e =

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00; T

u =

1%; B

= 2

0.80

0.85

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1.00

1.05

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3.8

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expt

, B=

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mp,

B=

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pt, B

=1

com

p, B

=1

expt

, B=

0co

mp,

B=

0

4.4

y/bl

ade

spac

ing

streamwise velocity/mid-channel velocity

Fig

. 11

Com

paris

on o

f wak

e ve

loci

ty p

rofil

e at

0.6

2 ax

ial c

hord

dow

nstr

eam

fro

m th

e bl

ade

trai

ling

edge

for

Re

= 50

,000

; T

u =

1%; B

= 0

, 1, 2

7N

ASA

/CR

—20

02-2

1168

9

Page 12: Low-Pressure Turbine Separation Control— Comparison · PDF fileHelp from Dr. Richard Rivir of the Air Force Research Laboratory and Major Jeffrey Bons of the Air Force ... Royal

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the

use

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Js)

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a lo

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turb

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(LPT

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ade

at lo

w R

eyno

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num

bers

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com

puta

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l res

ults

are

also

com

pare

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ith th

e ex

peri

men

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ata

for

stea

dy V

GJs

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s fo

und

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code

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erm

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the

prop

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catio

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the

sepa

ratio

n po

int o

n th

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ctio

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rfac

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the

base

line

blad

e (w

ithou

t any

VG

J) f

or R

eyno

lds

num

bers

of

50,0

00 o

rle

ss. A

lso,

the

code

find

s th

at th

e se

para

ted

regi

on o

n th

e su

ctio

n su

rfac

e of

the

blad

e va

nish

es w

ith th

e us

e of

VG

Js.

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ever

, the

sep

arat

ed r

egio

n an

d th

e w

ake

char

acte

rist

ics

are

not w

ell p

redi

cted

. The

wak

e w

idth

is g

ener

ally

over

-pre

dict

ed w

hile

the

wak

e de

pth

is u

nder

-pre

dict

ed.