modeling of gasoline hollow cone spraymodeling of...

Applied Mechanics

Modeling of Gasoline Hollow Cone SprayModeling of Gasoline Hollow Cone Spray Using OpenFOAMg p

Chen Huang PhD student

Department of Applied MechanicsDepartment of Applied MechanicsChalmers University of Technology

CERC5th OpenFOAM Workshop / June 21- 24, 2010, Gothenburg

Applied Mechanics

O tli eOutline1. Motivation

2 M difi i i O FOAM Lib2. Modifications in OpenFOAM Library

3 Modelling of Gasoline Hollow Cone Spray3. Modelling of Gasoline Hollow Cone Spray

4 Conclusions4. Conclusions


Applied Mechanics

M ti tiMotivation Wh O FOAM ?

License free industryP i i f ( bj i d C ) f i l i

Why OpenFOAM ?

Promising features (object oriented, C++) for implementing new models academia

High demand on usersHigh demand on usersSpace for improvement


Applied Mechanics

M difi ti i O FOAM LibG li ti

Modifications in OpenFOAM LibraryGasoline properties

http://www.tfd.chalmers.se/~hani/kurser/OS_CFD_2009/ChenHuang/OFProject0122.pdf

1. Properties from KIVA fuel library:1) vapour pressure (pv), 2) heat of vapourization (hl)2) heat of vapourization (hl), 3) liquid heat capacity (cp), 4) liquid enthalpy (h), 5) id l h i ( ) table5) ideal gas heat capacity (cpg), 6) liquid viscosity (mu), 7) liquid thermo conductivity (K),

table

8) surface tension (sigma), 9) molecular weight (W), 10) critical temperature (Tc).


) p ( )

Applied Mechanics

Gasoline propertiesGasoline properties

2. Properties from thermophysical functions:1) second virial coefficient (B) (C8H18), 2) diff i i (D) (C H )2) vapour diffusivity (D) (C7H16).

3. Density (rho) is taken from the book*

* Joseph A. Schetz, Allen E. Fuhs, Handbook of Fluid Dynamics and Fluid Machinery volume one Fundamentals of Fluid Dynamics p 156-157


Machinery, volume one Fundamentals of Fluid Dynamics. p 156 157.

Applied Mechanics

Gasoline properties4. Properties from mixing rule* based

IC H C H d C H

Gasoline properties

on IC8H18, C7H8, and C7H16: 1) vapour viscocity (mug), 2) vapour thermo conductivity (Kg),

ii

im QyQ 3) critical pressure (Pc), 4) critical volume (Vc), 5) critical compressibility factor (Zc),

is a mixture parameter.is a liquid or vapor mole fraction

mQ

y) p y ( ),6) triple point temperature (Tt), 7) triple point pressure (Pt), 8) normal boiling temperature (Tb)

is a liquid or vapor mole fraction.

is a property of a pure liquid or vapor.iy

iQ

8) normal boiling temperature (Tb), 9) dipole moment (dipm), 10) Pitzer’s ascentric factor (omega), 11) solubility parameter (delta)11) solubility parameter (delta).

*Robert C. Reid, John M. Prausnitz, Bruce E. Poling, The Properties of Gases & Liquids


, , g, p qFourth Edition. p 75.

Applied Mechanics

Implementation of gasoline properties

Description of thermophysical functions and liquid library

Implementation of gasoline properties

Description of thermophysical functions and liquid library

K_h

thermophysicalFunctions NSRDSfunc0 IC8H18 liquid

h_cp_

scalar

•The abstract class and its sub-classes are linked with blue arrows•A pink dashed arrow is used if a class is contained or used by another class. The arrow is labeled with the variable(s) through which the pointed class or


( ) g pstruct is accessible.

Applied Mechanics

h h l f d l d l bNew thermophysical functions and liquids library

thermophysicalFunctions NSRDSfuncgSigma gasoline liquidsigma_

thermophysicalFunctions NSRDSfuncgSigma gasoline liquid

scalar

•Class gasoline based on class IC8H18•Class NSRDSfuncgSigma based on class NSRDSfunc6•Private data sigma[56]: gasoline surface tension from 0-550K with 10 K as interval.•NSRDSfuncgSigma function is a linear interpolation function which returns


the surface tension at specified temperature.

Applied Mechanics

Ch k h l f lCheck the implementation of gasoline properties

M dif h b k d l hi h h f i• Modify the break-up model which uses the surface tension, eg, myReitzDiwakar.C

• Add Info commands to output the temperature and corresponding dd o co a ds to output t e te pe atu e a d co espo d gsurface tension

• Check the log fileW t– We got

– T = 320.326– sigma = 0 0163615sigma = 0.0163615


Applied Mechanics

Modifications in OpenFOAM dieselSpray LibraryModifications in OpenFOAM dieselSpray LibrarySpray models

Standard OpenFOAM Modifications in OpenFOAMmodels

Injector type Unit injector with constant

Cd

Unit injector with varied

CdCd Cd

Injector model

Hollow cone Pressure swirl

Pressure swirl with correct

d0

Primary break up

“Rosin-Rammler”

LISA Correct Rosin-Rammler

LISA with correctbreak-up Rammler Rammler correct Rosin-

Rammler

S d TAB R i TAB i hSecondarybreak-up

TAB with chi-square

Reitz-Diwakar

TAB with Rosin-Rammler


Collision O’Rourke Trajectory Bug fixedO’Rourke

Bug fixed trajectory

Applied Mechanics

Comparison of Rosin-Rammler pdfComparison of Rosin Rammler pdf

“R i R l ” C t R i R l

nDn

eDDf

nDn

eDnDf

1“Rosin-Rammler” Correct Rosin-Rammler


e

f

n = 2; = 20 m;

Applied Mechanics

Test of Rosin-Rammler pdfTest of Rosin Rammler pdf


Hollow cone injector, w/o break-up model, 5000 parcels.

Applied Mechanics

Comparison of Rosin-RammlerComparison of Rosin RammlerCDF based on the test


Applied Mechanics

Spray modelsSpray modelsSpray models

Original OpenFOAM Modified OpenFOAMmodels


Cd


CdCd Cd

Injector model

Hollow cone Pressure swirl Pressure swirl with

correct d0

Primary break up

“Rosin-Rammler”

LISA Correct Rosin

LISA with correctbreak-up Rammler Rosin-

Rammlercorrect Rosin-

Rammler

S d TAB R i Di k TAB i hSecondarybreak-up

TAB with chi-square

Reitz-Diwakar TAB with Rosin-Rammler


Collision Bug fixedO’Rourke


Applied Mechanics

Comparison of droplet distribution generated byComparison of droplet distribution generated by Rosin-Rammler pdf

Original

Correct

0 3 SOI 0 6 SOI 1 0 SOI0.3 ms aSOI 0.6 ms aSOI 1.0 ms aSOI

Rosin-Rammler (=20 m, n=2)


(Tgasol=243 K, Tair=350 K, pinj=200 bar)

Applied Mechanics

Comparison of liquid penetration and SMD generatedComparison of liquid penetration and SMD generated by Rosin-Rammler pdf


Applied Mechanics

Modifications to LISA atomization model

DDDf

DeDfD 2

21. Pdf after sheet break-up

eDf

eDf

2. SMDd

13133

12

1

12

1

22

0

3nn

dDDfD

dDDfDdSMD

for Rosin-Rammler distribution n=2

110 nndDDfD

SMDd 4


for Rosin-Rammler distribution n=2, SMDd

3