NASA Contractor Report 3481

Design of Prototype Charged Particle Fog Dispersal Unit

Frank G. Collins, Walter Frost, and Philip Kessel FWG Associates, Inc. TiZZahoma, Tennessee

Prepared for George C. Marshall Space Flight Center under Contract NAS8-33541

NASA National Aeronautics and Space Administration

Scientific and Technical Information Branch

1981

https://ntrs.nasa.gov/search.jsp?R=19820008785 2020-06-03T08:26:26+00:00Z

ACKNOWLEDGMENTS

The work reported herein was supported by the National Aeronautics and Space Administration, Marshall Space Flight Center, Space Sciences Laboratory, Atmospheric Sciences Division, under Contract NAS8-33541.

The authors are indebted to Mr. A. Richard Tobiason o f the Office of Aeronautics and Space Technology (OAST) , NASA Headquarters , Washington, D. C., for his support of this research. Special thanks are given to Mr. Dennis W. Camp of Marshall Space Flight Center who was the scien- tific monitor of the program and provided considerable technical advice and input to the final documentation. Also, the authors are appreciative of the technical discussions with various personnel of the FAA, Naval Research Laboratories, and Energy Innovations, Inc.

i i

TABLE OF CONTENTS

SECTION PAGE

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . 1

2.0 DESIGN OF PROTOTYPE CHARGED PARTICLE FOG DISPERSAL UNIT . . . . 2

2.1 Previous Designs . . . . . . . . . . . . . . . . . . . . . 2

2.2 Description o f Prototype Unit . . . . . . . . . . . . . . 2

2.3 Design o f Prototype Unit . . . . . . . . . . . . . . . . . 10

3.0 DRAWINGS OF PROTOTYPE CHARGED PARTICLE FOG DISPERSAL UNIT . . . 20 4.0 DESIGN OF VERIFICATION EXPERIMENTS FOR FOG DISPERSAL UNIT . . . 24

5.0 CONCLUDING REMARKS . . . . . . . . . . . . . . . . . . . . . . 27

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

APPENDIX.. BIBLIOGRAPHY OF WORK RELATED TO ELECTROFLUID DYNAMIC POWER GENERATION . . . . . . . . . . . . . . . . . . . . . . . . 31

i i i

LIST OF ILLUSTRATIONS

FIGURE TITLE PAGE

1 Prototype Fog Dispersal Nozzle . . . . . . . . . . . . . . . 5

2 Schematic of Charge Spray Nozzle . . . . . . . . . . . . . . 8

3 Nozzle Controls . . . . . . . . . . . . . . . . . . . . . . 9

4 Typical Electrode Configuration of EFD Test Rig [25] . . . . 11

5 Current a s a Function of the Needle Posit ion i n Nozzle [25] . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

6 Corona Needles . . . . . . . . . . . . . . . . . . . . . . . 13

7 Configuration Factor o f G f o r Both the Two-Dimensional and Axisymmetric Geometries [26] . . . . . . . . . . . . . . . . 15

8 Lines of Constant Normalized Power as a Function of M* and V f o r a Gas w i t h k = 1.4. The f i e l d strength a t the generator entrance i s E b [26] . . . . . . . . . . . . . . . . . . . . 16

9 Cross Section o f Prototype Nozzle . . . . . . . . . . . . . 21

10 Details o f Prototype Nozzle . . . . . . . . . . . . . . . . 22

11 Details of Prototype Fog Dispersal System . . . . . . . . . 23

i v

L IST OF TABLES

TABLE TITLE PAGE

1 Features o f Prototype Nozzle . . . . . . . . . . . . . . . . 3

2 Nozzle Character is t ics . . . . . . . . . . . . . . . . . . . 6

3 Character is t ics o f Nozzle Droplets . . . . . . . . . . . . . 13

4 Corona Scal ing Laws . . . . . . . . . . . . . . . . . . . . . 18

5 Quant i t ies t o be Measured . . . . . . . . . . . . . . . . . . 25

V

D

Eb

Ebo

G

h

I

5 M

M*

P

R

V

V

V

-

-

W

Symbols

E 0

'e

NOMENCLATURE

Normalized charge d e n s i t y

F i e l d s t r e n g t h a t t h e genera tor entrance

Gas breakdown e l e c t r i c f i e l d

Con f igu ra t i on f a c t o r

Channel l e n g t h

Cur ren t a t a t t r a c t o r

J e t c u r r e n t

Mach number of gas

Mach number based on l o c a l speed o f sound

Pres sure

Channel r a d i u s

Gas v e l o c i t y

Normalized p o t e n t i a l a p p l i e d t o nozz le

P o t e n t i a l a t a t t r a c t o r

Channel w i d t h

P e r m i t t i v i t y of gas

E l e c t r i c charge d e n s i t y

v i

1.0 INTRODUCTION

Previous r e p o r t s reviewed the e a r l i e r e f f o r t s t o d isperse f o g E l ] and examined the t h e o r e t i c a l aspects o f t h e charged p a r t i c l e f o g d i s -

p e r s i o n technique i n g r e a t d e t a i l [ Z ] .

appeared t o be a v i a b l e technique based on the rev iew o f t h i s p rev ious work, b u t i t was concluded t h a t f u r t h e r exper imental i n v e s t i g a t i o n would

be r e q u i r e d t o remove remaining doubts. Th is r e p o r t d e t a i l s t he design

of a p ro to type charged p a r t i c l e fog d i spe rsa l u n i t and o u t l i n e s t h e

exper imental program t o eva lua te the u n i t . The c o n s t r u c t i o n and evalua-

t i o n of t h e u n i t w i l l be performed i n the n e x t phase o f t h i s work.

techniques used t o design the u n i t a r e discussed i n Sec t ion 2.0, and

Sec t ion 3.0 conta ins d e t a i l e d plans f o r t h e p ro to type u n i t . d i x conta ins a b ib l i og raphy of work performed i n e l e c t r o f l u i d dynamic

power genera t ion t h a t was found t o be h e l p f u l i n the design o f t he p ro to type u n i t .

The charged p a r t i c l e concept

The

The appen-

2.0 DESIGN OF PROTOTYPE CHARGED PARTICLE FOG DISPERSAL UNIT

2.1 Previous Designs

Previously used charged pa r t i c l e fog dispersal un i t s and t h e i r operation were described i n the e a r l i e r reports [1 ,2] and in References [3] through [lo]. b u t the resu l t s will be f ree ly used. the prototype uni t the experience tha t had been gained by other organi- zat ions, i . e . , the Curtiss-Wright Corporation, Marks Polarized Corpora- t ion , University of Dayton Research I n s t i t u t e , and the Aerospace Research Laboratories a t Wright-Patterson Air Force Base, on the design of e lec t rof lu id dynamic (EFD) energy conversion devices was found t o be of considerable assistance because of the great s imi l a r i t y of EFD devices and charged par t ic le fog dispersion devices. re la ted t o EFD devices i s included in the appendix. Certain features of the nozzles were found t o have s igni f icant influences upon increasing the amount of power generated by EFD devices. incorporated i n t o the design of the prototype fog dispersal un i t and f l e x i b i l i t y has been included t o determine whether improved performance can be obtained by u t i l i z ing these fea tures .

T h i s previous work will not be reviewed again here, D u r i n g the course of the design of

A bibliography of work

These features have been

2 . 2 Description of Prototype-Unit

The features of the prototype charged pa r t i c l e fog dispersal un i t t o be described in t h i s report are shown in Table 1 . gations of fog dispersal systems [2] or e lec t rof lu id dynamic energy conversion systems (see appendix) have used various types of charge c a r r i e r s (ions [3,11]; water droplets [4,5,6]; and helium bubbles [7 ] ) t ha t were charged e i the r by e l e c t r o s t a t i c induction [8] or by charge t ransfer in a corona discharge [12,13,14,15]. accelerated by e l ec t ros t a t i c means [16] or by viscous coupling t o an

Previous inves t i -

The charge c a r r i e r s were

2

Mois t a i r acce le ra ted i n supersonic nozz le having f i x e d e x i t Mach number.

Water d r o p l e t s formed by homogeneous n u c l e a t i o n i n expanding nozz le f low. Water d r o p l e t s charged i n corona d ischarge i n s i d e nozz le.

Va r iab le nozz le l e n g t h t o sonic r a d i u s . Va r iab le corona d ischarge l o c a t i o n .

Ad jus tab le corona needle l o c a t i o n . Va r i a b l e stagna t i on chamber spec i f i c humi d i ty . Var iab le corona need1 e shape. Constructed from a t ransparent m a t e r i a l .

a c c e l e r a t i n g a i r s t ream [17].

t h a t t he optimum e f f i c i e n c y o f charge t r a n s p o r t cou ld be ob ta ined by

charg ing smal l water d r o p l e t s i n a corona d ischarge and a c c e l e r a t i n g

these by v iscous coup l i ng w i t h a i r i n a supersonic nozz le [12,17].

I t was concluded from t h i s p rev ious work

The p ro to type charged p a r t i c l e f o g d i spe rsa l u n i t ope ra t i on w i 11

now be descr ibed i n d e t a i l . t h r o a t ana expansion nozzle. A t Suiiie po i i i t , coi idei isat io i i fro; spoi i ta-

neous (homogeneous) nuc lea t i on occurs. Heterogeneous condensation i s

n o t u s u a l l y considered an e f f e c t i v e mechanism f o r nozz le f l ows [18].

mo is t a i r expansions the nuc lea t i on and growth processes a r e uncoupled

s ince homogeneous nuc lea t i on i s over be fore any apprec iab le amount o f

growth has occurred [19]. The d rop le ts grow q u i c k l y f o r some d i s tance

through the "condensation zone" and then more s l o w l y up t o the nozz le

e x i t [19,20]. The l o c a t i o n o f the p o i n t where homogeneous n u c l e a t i o n

takes p lace i s dependent upon the average temperature g r a d i e n t a long t h e

nozz le because, f o r a f i x e d e x i t Mach number, t h e amount o f supercoo l ing

increases w i t h an increase i n the average temperature g r a d i e n t a long t h e

nozz le (dT/dx). Th is temperature g r a d i e n t w i l l be v a r i e d by va ry ing t h e

l e n g t h o f the nozzle.

Mois t a i r i s expanded through the son ic

I n

3

The location f o r homogeneous nucleation and the drople t growth r a t e a r e extremely sensitive t o the r e l a t i v e humidity i n the stagnation region and, i n addition, the droplet growth r a t e i n the "condensation zone" depends on the length of the nozzle [18]. produced i n short nozzles and large drops i n long nozzles. s p e c i f i c humidities i t has been noted t h a t the e n t i r e flow is foggy down- stream of the condensation location. current f o r e lec t rof lu id dynamic energy conversion nozzles having an exit Mach number of 2.0 was obtained w i t h a stagnation chamber r e l a t i v e humidity of 17 percent. required t o obtain optimum r e s u l t s will be explained i n Section 2 . 3 .

In general , small drops a r e A t h i g h

Lawson [21] found t h a t the maximum

T h i s ra ther low value of r e l a t i v e humidity

The corona discharge must be placed a f t e r condensation has occurred and a l so a t the location where the droplets have grown t o a desirable size t o be able t o carry the necessary charge [2]. Therefore, several corona locations will be examined. In addi t ion, several corona shapes wil l be examined and the needle location will be adjustable r e l a t i v e t o each corona discharge location.

The nozzle will be made out of a transparent p l a s t i c i n order t o v isua l ize the flow and corona discharge w i t h i n the nozzle. Further explanation of the features of the prototype nozzle will be given l a t e r .

A schematic of the prototype fog dispersal nozzle is shown i n Figure 1. pressure and then f i l t e r e d t o remove a l l moisture, o i l droplets , and s o l i d par t ic les . The a i r then will be mixed w i t h a controlled amount of atomized water--to control the s p e c i f i c humidity--in a mixing tube. T h e purpose of the mixing t u b e i s t o allow f o r complete evaporation of the water i n t o the dry a i r . The swirl induced by the mix ing tube wil l be removed by a honeycomb. The humid a i r will be decelerated in to the stagnation chamber and then expanded through the converging/diverging nozzle unt i l i t will emerge a t the nozzle ex i t a t a supersonic Mach number. The diverging portion of the nozzle will be conical w i t h the length much greater than the diameter a t the throa t . flow i n the nozzle will be very nearly cy l indr ica l .

Atmospheric a i r will be compressed t o the proper stagnation

Therefore, the

4

N N 0 S

0 L a

L 3 m

5

The water vapor will condense near the throa t d u r i n g the expansion process. The droplets t h a t will be formed wil l be small enough t o be car r ied by viscous drag along w i t h the a i r . T h u s , they will be continu- ously accelerated i n the nozzle.

The corona needle will be attached t o a veined support i n the s t i l l i n g chamber. The a t t r a c t o r s can be placed a t two locations and two lengths of nozzle will be examined. The overall length o f the nozzle portion of the uni t will be approximately 31.75 cm (12.5 i n ) t o 40.64 cm (16 i n ) and 7.62 cm ( 3 i n ) i n diameter. The e n t i r e system can be disas- sembled quickly and reassembled i n a new configuration.

The estimated c h a r a c t e r i s t i c s of the nozzle a r e shown i n Table 2. The e x i t Mach number i s 1.35. This i s the Mach number t h a t has been used by Gourdine [5] and the choice of the Mach number will ‘be exDlained l a t e r . A 7.08 x an e x i t Mach number of 1.35 f ixes the maximum diameter of the nozzle throa t a t 0.43 cm (0.168 i n ) . i s i n i t i a l l y dry will be 1 .42 x m3/s (0.135 g a l / h r ) , which will r e s u l t i n a re la t ive humidity i n the stagnation region of 100 percent. The stagnation pressure will be 3.01 x 10 N / m

m3/s (15 SCFM) compressor will be used which f o r

The maximum water flow r a t e in to a i r t h a t

5 2 (43.6 psia) f o r an

TABLE 2. Nozzle Character is t ics .

E x i t Mach number 1.35

Minimum diameter 0.43 cm (0.168 i n )

A i r f 1 ow r a t e

Maximum water flow rate

7.08 x m3/s (15 SCFM)

1.42 x m3/s (0.135 ga l /hr )

Stagna t i on pressure 3.01 x lo5 N / m 2 (43.6 ps ia )

Nozzle length t o sonic diameter r a t i o 40/60

Mach number a t corona 1.07/1.15

Current (maximum) 52 x amps

Charge t o mass r a t i o 0.37 coul/kg

6

5 2 atmospher ic pressure of 1.01 x 10 N/m (14.7 p s i a ) . The s tagna t ion

pressure i s f i x e d by a d e s i r e t o e l i m i n a t e shocks a t t he e x i t o f t h e

nozz le s ince shocks w i l l r e s u l t i n breakup and evapora t ion o f the water d r o p l e t s .

t h e diameter a t the nozz le th roa t .

e i t h e r a t a Mach number of 1.07 o r 1.15. The maximum es t imated c u r r e n t

w i l l be 52 microamps and t h a t w i l l r e s u l t i n a charge t o mass r a t i o o f 0.37 coul /kg. promise between a d e s i r e t o increase the average temperature g r a d i e n t

a long w i t h nozzle, t o increase the amount o f supersa tura t ion , and the need t o keep the e x i t Mach number low i n o rder t o have as h i g h a charge d e n s i t y as poss ib le w i t h o u t a breakdown f i e l d a t t he e x i t of t he nozz le.

The nozz le l e n g t h t o diameter r a t i o w i l l be 40 o r 60 based on

The corona r e g i o n w i l l be p laced

The e x i t Mach number w i l l l a t e r be shown t o be a com-

The e l e c t r i c a l connect ions t o the nozz le a r e shown i n F igure 2. The corona needle w i l l be grounded whereas t h e a t t r a c t o r w i l l be p laced

a t a h i g h b u t v a r i a b l e p o s i t i v e p o t e n t i a l .

nega t i ve corona which i s t he des i rab le type o f corona because o f t h e

presence o f e lec t ronega t i ve gases i n a i r [2,22,23,24]

w i l l be used t o measure t h e cathode o r needle c u r r e n t and t h e a t t r a c t o r

o r anode cu r ren t . The p roper t i es o f t h e d ischarge w i 1 be ad jus ted

u n t i l t he a t t r a c t o r c u r r e n t i s near ly zero and t h a t w i l l r e s u l t i n t h e

maximum j e t cu r ren t .

Th i s w i l l r e s u l t i n a

Microammeters

The nozz le c o n t r o l s a re shown schemat ica l l y i n F igu re 3. The a i r

f rom the compressor w i l l be f i l t e r e d t o remove o i l and water d r o p l e t s .

It w i l l then be d iv ided; p a r t o f t he a i r be ing used t o p ressu r i ze the

water s torage b o t t l e and p a r t o f t he a i r go ing d i r e c t l y i n t o t h e nozz le.

Water l e a v i n g the s to rage b o t t l e w i l l be s t r a i n e d and t h e f l o w r a t e w i l l be measured w i t h a ro tameter . The water w i l l f l o w through a c a p i l l a r y

tube t h a t w i l l atomize the water when i t meets w i t h t h e a i r . The

a i r / w a t e r m ix tu re w i l l then go through the m ix ing tube where t h e water

w i l l evaporate be fore reaching the nozzle. A l l q u a n t i t i e s , i .e . , a i r

pressure, water pressure, and w a t e r f l o w r a t e , can be cont inuous ly

c o n t r o l l e d i n o rder t o op t im ize the performance o f t h e nozz le.

7

W N N 0 c

- 2 L m n

Y a J v >

0

9

2.3 Design o f Pro to type U n i t

I n t h i s s e c t i o n the r a t i o n a l e f o r the des ign d e c i s i o n s t h a t were descr ibed i n t h e prev ious s e c t i o n w i l l be g iven. F i r s t , t h e v a r i a b l e

needle l o c a t i o n i s examined.

genera t ion devices i n d i c a t e d t h a t t h e o u t p u t c u r r e n t can be increased by a d j u s t i n g the p o s i t i o n o f t h e needle r e l a t i v e t o t h e a t t r a c t o r [25].

The apparatus used i n these s tud ies i s shown i n F i g u r e 4. High-pressure

a i r t h a t proceeded through the corona d ischarge l o c a t e d a t t h e nozz le

s o n i c o r i f i c e was mixed w i t h medium-pressure secondary a i r be fore pro-

ceeding through a grounded e l e c t r o d e and i n t o t h e convers ion duct .

c o n f i g u r a t i o n i s shown t o i n d i c a t e t h e r e l a t i v e p o s i t i o n o f t h e corona needle t o the a t t r a c t o r nozzle.

t o t h e a t t r a c t o r nozzle, t h e c u r r e n t i s found t o have a maximum--as

i l l u s t r a t e d i n F igure 5. Several corona needle l o c a t i o n s r e l a t i v e t o t h e a t t r a c t o r w i l l be examined d u r i n g t e s t i n g o f t h e nozz le.

Studies on e l e c t r o f l u i d dynamic power

The

By v a r y i n g the needle l o c a t i o n r e l a t i v e

I t should a l s o be n o t i c e d t h a t t h e r e s u l t s shown i n F igure 5 i n d i -

c a t e t h a t improved performance was obta ined w i t h a na i l -head needle ( a #8 n a i l was a l s o used [21]) compared t o a sharp needle.

t h a t t h e low-pressure r e g i o n and wake t h a t were c rea ted downstream o f t h e n a i l head was advantageous f o r charg ing the d r o p l e t s because t h e

d r o p l e t s were t rapped f o r a p e r i o d o f t ime i n t h e separated r e g i o n where

t h e corona discharge c u r r e n t i s increased and t h e r e f o r e improved p e r f o r - mance was obtained. needles t h a t w i l l be examined i n the s tudy t o t r y t o o b t a i n t h e maximum

c u r r e n t f rom t h e nozzle.

I t was f e l t

F igure 6 i n d i c a t e s the geometry o f t h e corona

I t i s d e s i r a b l e t o est imate t h e c h a r a c t e r i s t i c s o f t h e d r o p l e t s

t h a t can be expected t o be l e a v i n g the nozz le . t e r i s t i c s are shown i n Table 3.

making these est imates.

percent i n the s tagnat ion chamber a t a temperature of 21.1" C (70" F ) .

It was assumed t h a t a l l o f the d r o p l e t s were charged t o t h e breakdown

f i e l d a t t h e i r sur face . Th is then a l lowed the number o f e l e c t r i c a l

charges p e r p a r t i c l e and the m o b i l i t y of t h e d r o p l e t t o be est imated [2].

These est imated charac-

The f o l l o w i n g assumptions were used i n

The water f l o w r a t e was assumed t o be 1.42 x

m3/s (0.135 g a l / h r ) which would g i v e a r e l a t i v e humid i ty o f 100

10

n Lo N U

cc 0

11

n v) w w a H 4 0 a 0

H

I- z w

a

-

a a 3 0

I I 1600 ,

1400

1200

iooa

80C

60C

40C

20c

(

I I

c I " I - 0, -I

I I

- r

I I 5/16 M 2 N O Z Z L E

Pp = 80 a t m .

Ps'= 16 a t m .

0

zi - .z I '1

I

x

I I I AEROSOL (Ha 0

I I

I I

I 1

I I IONS

7 I I I I I I

I /-< I

. I 6 . I 2 .O 8 .o 4 0

N E E D L E TIP POSITION ( i n c h e s 1

Figure 5 Current as a function of the needle posit ion in nozzle [25].

12

Figure 6 Corona needles.

TABLE 3. Character is t ics of Nozzle Droplets.

Water flow r a t e = 1.42 x All p a r t i c l e s charged t o breakdown f i e ld a t surface.

m3/s (0.135 gal /hr)

Maxi m u m Charges

Par t ic l e Pa r t i c l e Per Maxi mum Charae Radius F1 ux Pa r t i c l e Current Mobi 1 i t y Density

(m) (#/sec) ( # > (amp 1 (m2/vol t sec) (couI/m3)

5x1 O-' 2 . 7 ~ 1 O1 0.05 2 . 2 5 ~ 1 0-3 1 . 1 0 ~ 1 0-7 2 . 4 3 ~ 1 0-1

3 . 4 ~ 1 0 ~ ~ 0.21 1 . 1 ~ ~ 1 0 - ~ 1.12x10-~ 1 .2lX1o-l

5x1 0-8 2 . 7 ~ 1 0 14 5.20 2 . 2 5 ~ 1 0-4 1 .41 xl 0-7 2 . 4 3 ~ 1 0-2

3 . 4 ~ 1 0 ~ ~ 20.80 1 . ~ x l O - ~ 1 . 8 2 ~ 1 0 - ~ 1 . 2 1 ~ 1 0 - ~

Because of the Cunningham correction f a c t o r [2], the mobili ty i s seen t o be approximately constant f o r par t ic les i n this s i z e range and i s approxi- mately m2/volt sec.

I f the flow w i t h i n the nozzle is i n equilibrium, then the equi l ib-

This estimate i n d i - rium drop radius can be estimated from a knowledge of the r e l a t i v e humidity a t any pa r t i cu la r point along the nozzle. ca tes t h a t the droplets w i t h i n the nozzle a r e of extremely small diameter

[18,19,20]. The droplets usually have diameters of 10 A" t o 400 A" (1 A" = microns). Therefore, the r ad i i o f the p a r t i c l e s examined i n

13

Table 3 are quite small, and i t i s f e l t t h a t t h i s i s the probable range f o r the droplet s i ze from these nozzles [5,19]. flow r a t e , the pa r t i c l e f lux r a t e can be determined, assuming spherical pa r t i c l e s . From the maximum charge per p a r t i c l e and the p a r t i c l e f lux r a t e , the maximum current from the nozzle can be determined.

Thus, knowing the water

While the calculat ions t h a t were performed t o obtain the r e su l t s in Table 3 are straightforward, the r e su l t s a r e in a l l probabi l i ty incorrect because no use has been made of the equations of electrodynamics. Magnetic f i e l d e f f ec t s a re negligible because of the small currents and only e l e c t r o s t a t i c e f f ec t s need t o be considered. Therefore, the e lec- t r i c f i e l d i s described by the Poisson equation. Minardi [26] computed the performance charac te r i s t ics of e lec t rof lu id dynamic power generation nozzles assuming tha t the charge c a r r i e r was a col loid such a s a water droplet . gas and charged col loids flowed, t h a t the gas veloci ty was constant within the l o n g cyl inder , t h a t the charge density was constant within the cyl inder , and t h a t there was no s l i p veloci ty between the col loid and the airstream. mobility of the col loids i s zero. the charged par t ic les were neglected. used t o determine the e l e c t r i c f i e l d within and external t o the nozzle [27,28,29].

He assumed tha t he had a very long cylinder t h r o u g h which the

The l a s t assumption amounts t o assuming t h a t the Turbulent spreading and diffusion o f

The Poisson equation was then

The maximum f i e l d was found t o occur a t the nozzle e x i t .

The parameters used in his analysis a r e the following:

PehG D = - - - normalized charge density

‘oEbo

G = l + F - (1 - (F]2}2 = configuration f ac to r i f R / h << 1

M* = M2 0.833 + 0.167M7-

where p e i s the e l e c t r i c charge densi ty , R i s the radius of a channel of length h , E

e l e c t r i c f i e l d i n the stagnation chamber, M i s the gas Mach number, and M* i s the Mach number based on the local speed o f sound.

is the permit t ivi ty of the gas, E b o i s the gas breakdown 0

14

The factor G is shown in Figure 7. For a very long channel, where the radius is much less than the length of the channel, the factor G can be approximated by the equation given and is then a very small number. Lines of constant normalized output power from the electrofluid dynamic nozzle are shown in Figure 8 as a function of M* and v, the normalized potential applied to the nozzle. The results of this figure can be used in the prototype nozzle because the line a = 0 gives the values of D for breakdown in the channel as a result of the charge density alone.

Axisymmetric

G

Two-Dimensional

I I I

0 0.5 1.0 1.5 2.0 2.5 3.0

R/h or w/h

Figure 7 Configuration factor of G for both the two-dimensional and axisymmetric geometries [26].

As previously mentioned, the maximum electric field occurs at the nozzle exit and therefore breakdown will occur there first. nozzle Mach number, M* can be determined. Then from Figure 8 the value o f D can be obtained. It should be noted that lines of constant D intersect the M* axis at v = 0. From the value of D obtained from this figure, the maximum value of the charge density within the nozzle can be determined and then the maximum current is given by

For a given

I . = p VnR2 J e

where V is the gas velocity.

15

M*

2.4 I

- S P = 0 SM*

D=O

Figure 8 Lines of constant normalized power a s a function of M* and v f o r a gas w i t h k = 1.4. The f i e l d strength a t the generator entrance i s Eb [26].

The above analysis was applied t o the prototype nozzle assuming t h a t the nozzle was a cylinder w i t h radius equal t o the radius a t the nozzle throat . The breakdown f ie ld was found t o occur a t the nozzle exi t when the charge density reached 5.64 x coul/m (M* = 1.266 f o r an ex i t Mach number of 1.35) f o r both nozzle l e n g t h t o diameter r a t i o s tha t will be used i n the prototype nozzle. T h i s yields a maximum proto- type nozzle current of 52.3 microamps, w h i c h i s considerably less than

3

16

t h e est imated c u r r e n t s shown i n Table 3. Th i s maximum nozzle c u r r e n t would occur f o r any p a r t i c l e rad ius w i t h i n the range considered and i t

t h e r e f o r e appears t h a t t h e nozzle c u r r e n t i s c o n t r o l l e d by the breakdown

o f t he f i e l d a t t h e nozz le e x i t r a t h e r than the d e t a i l s o f t he charg ing

process, p rov ided i t i s s u f f i c i e n t l y e f f i c i e n t . I n a d d i t i m , under t h e

assumptions t h a t were made i n c a l c u l a t i n g Table 3, i t i s seen t h a t the

s tagna t ion chamber r e l a t i v e humid i ty can be g r e a t l y reduced and t h e

nozz le w i l l d e l i v e r t he same c u r r e n t (2.3 percent f o r 5 x lo - ’ m r a d i u s

d r o p l e t s t o 47 percent f o r

r a t e can be g r e a t l y reduced.

r e l a t i v e humid i t y o f 17 percent [ Z l ] .

m r a d i u s d r o p l e t s ) , i . e . , the water f l o w

Lawson ob ta ined optimum r e s u l t s w i t h a

As a v e r i f i c a t i o n o f t he a p p l i c a b i l i t y o f t h i s a n a l y s i s t o t h e

c u r r e n t f rom a f o g d i spe rsa l nozzle, i t was a p p l i e d t o t h e nozz le used

by Gourdine [5].

be 99 microamps w h i l e the c u r r e n t was measured t o be 100 t o 135 microamps.

Therefore, i t i s f e l t t h a t the a n a l y s i s o f M inard i can be a p p l i e d t o t h e

p r o t o t y p e nozz le and w i l l g i v e a reasonably accura te es t ima te o f t h e

maximum c u r r e n t t h a t can be expected f rom t h e nozzle.

t h e var ious features of t he pro to type nozz le w i l l be s tud ied t o determine the maximum c u r r e n t the nozz le w i l l d e l i v e r .

The ana lys i s es t imates t h a t t he maximum c u r r e n t would

Dur ing t e s t i n g ,

N o t i c e t h a t F igu re 8 i nd i ca tes t h a t t h e value o f D f o r breakdown o f t h e f i e l d a t the e x i t decreases as M* increases o r as the Mach number o f t h e nozz le e x i t increases. Therefore, increased charge d e n s i t y can be

ob ta ined by lower ing the Mach number. But t he condensation process

r e q u i r e s a minimum value o f the mean temperature g r a d i e n t across the

nozzle, which decreases as the e x i t Mach number i s increased ( f o r a

f i x e d l e n g t h t o son ic diameter r a t i o ) . Gourdine [ S I used nozzles having

an e x i t Mach number o f 1.35 and i t i s proposed t h a t t h e p r o t o t y p e nozz le

t h a t i s descr ibed i n t h i s r e p o r t have the same Mach number s ince t h i s

appears t o be a good compromise between these two competing e f f e c t s .

I t was des i red t o choose a s i z e f o r t he p r o t o t y p e nozz le t h a t cou ld

be economical ly manufactured i n l a r g e numbers and would a l s o p lace the

r e q u i r e d number o f charges i n t o the f o g i n a reasonable l e n g t h o f t ime.

The design t r a d e - o f f s t h a t are p o s s i b l e can be ob ta ined by examining the

17

scal ing laws for the corona discharge [12,22]. These scaling laws, which a re summarized i n Table 4, indicate the e f f e c t of varying the nozzle dimensions and the stagnation pressure upon the discharge. the dimensions of the nozzles a r e doubled, then the current can be increased by a fac tor of two. increased by a fac tor of four which r e s u l t s i n a four-fold increase i n the a i r volume flow r a t e i n standard cubic f e e t per minute. T h i s then

I f

However, the nozzle area then has been

requires a compressor of four times capacity. However, t h a t compressor i s approximately four times as expensive as the one f o r the or iginal nozzle while leading t o only a doubling of the nozzle current . f o r e , nozzles of a moderate s i z e a r e more economical than half the number of nozzles tha t a re twice as large since the compressor i s the most expensive component. nozzles t h a t he had examined would be su i tab le f o r an a i r p o r t appl icat ion [30,31]. Because of the a v a i l a b i l i t y of a r e l i a b l e 7.08 x 10 (15 SCFM) compressor, the prototype nozzle was designed f o r t h a t capacity

There-

Gourdine suggested t h a t the medium-sized

-3 3 m / s

TABLE 4. Corona Scaling Laws. ~- __ ___

Increase a l l dimensions by a fac tor a:

'e 'e,, - a

- -

Increase pressure from pN t o p :

Eb = E 1 breakdown f i e l d (Paschen ' s 1 aw) b ,N PN

P e = P P e,N PN

i = i 1 potential on a t t r a c t o r 'N

with an e x i t Mach number of 1.35. the prototype nozzle are given i n Tabie 2 .

The other expected cha rac t e r i s t i c s of

The unit has been designed to allow f o r the var ia t ion o f the fea- tu res l i s t e d in Table 1 . the unit ea s i ly modified t o allow optimization o f the design.

In addition, a t ten t ion has been paid t o making

19

3.0 DRAWINGS OF PROTOTYPE CHARGED PARTICLE FOG DISPERSAL UNIT

D e t a i l e d drawings o f t he p ro to type u n i t a r e shown i n F igures 9, 10,

and 11.

P l e x i g l a s u n i t s t h a t w i l l be sealed w i t h O-r ings. The u n i t w i l l be

b o l t e d together us ing threaded rods.

nozz le w i l l be cons t ruc ted f rom commercial ly a v a i l a b l e p i p e f i t t i n g s . The e n t i r e con t ro l u n i t and the nozz le w i l l be mounted on handtrucks t o

make the u n i t po r tab le .

The nozz le u n i t w i l l be cons t ruc ted of machined and p o l i s h e d

Connections t o the p ro to type

20

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m 0 rc

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0 c, 0

v) rc v) V V rc 5 b

TABLE 5. Q u a n t i t i e s t o be Measured.

Nozzle Proper t ies :

0 Stagnat ion pressure 0 Stagnat ion temperature 0 Stagnat ion r e l a t i v e humid i t y 0 E x i t Mach number 0 E x i t d r o p l e t s i z e

E l e c t r i c a l P roper t i es :

0 Charge dens i t y d i s t r i b u t i o n 0 E l e c t r i c f i e l d d i s t r i b u t i o n

Atmospheric Proper t ies :

0 Pressure 0 Temperature 0 R e l a t i v e humid i t y 0 V i s i b i l i t y 0 Wind v e l o c i t y

t h e e l e c t r i c f i e l d and t h e charge d e n s i t y e x t e r n a l t o t h e nozz le must be measured be fo re the nozz le i s turned on and d u r i n g the opera t i on o f t he

nozzle. I d e a l l y , the d i s t r i b u t i o n o f bo th q u a n t i t i e s must be measured

t o v e r i f y t he var ious theo r ies about t h e ex te rna l f i e l d [2]. This i s

d i f f i c u l t t o do because o f t he i n t e r f e r e n c e between t h e measuring i n s t r u -

ment and i t s support and connection t o the ground and t h e f i e l d t o be

measured, b u t these e f f e c t s can be minimized by c a l i b r a t i o n o f t h e

ins t ruments i n place.

The v e r t i c a l component o f the s t a t i c e l e c t r i c f i e l d w i l l be measured

us ing f i e l d m i l l s [32,33,34,35]. w i l l depend somewhat on t h e i r a v a i l a b i l i t y . The f i e l d m i l l s w i l l be

r e q u i r e d t o e i t h e r have a l a r g e dynamic range (10 t o 10

d i f f e r e n t se ts o f ins t ruments w i l l have t o be used so t h a t both the

background f i e l d and the f i e l d due t o t h e charged d r o p l e t s can be mea-

sured. The f i e l d m i l l s w i l l have t o be c a l i b r a t e d both i n t h e l a b o r a t o r y

and i n p lace i n the f i e l d . p l a t e s t o them and app ly ing a DC v o l t a g e between t h e p l a t e s .

The number o f f i e l d m i l l s t o be used

6 vo l t /m) o r two

They w i l l be c a l i b r a t e d by f i t t i n g l a r g e Comparison

25

w i t h a l a b o r a t o r y - c a l i b r a t e d f i e l d m i l l w i l l be r e q u i r e d i n t h e f i e l d

because o f t he i n f l u e n c e o f t he f i e l d mounting upon t h e c a l i b r a t i o n .

I t i s a l so necessary t o measure the space-charge d i s t r i b u t i o n i n

t h e atmosphere i n the reg ion of t he nozz le.

by Gourdine [5] and appears t o be the most u s e f u l method t o measure t h e

charge d e n s i t y a t cons iderable he igh ts above the ground [ 3 6 ] . Ca l ib ra -

t i o n i s d i f f i c u l t bu t comparison can be made between the est imates of t he charge dens i t y us ing the measurements of t he e l e c t r i c a l f i e l d and

Poisson 's equat ion and the cage measurement.

A cage technique was used

The remaining atmospheric measurements i n d i c a t e d i n Table 5 w i l l be

made us ing standard techniques.

p r e v i o u s l y [Z]. The complete f i e l d program was descr ibed

26

5.0 CONCLUDING REMARKS

The d e t a i l e d design of a p ro to type charged p a r t i c l e f o g d i s p e r s a l u n i t has been presented i n t h i s r e p o r t .

des ign a re w e l l understood and have been w ide ly used i n t h e p a s t bo th

f o r f o g d i spe rsa l u n i t s and f o r e l e c t r o f l u i d dynamic power genera t ion .

Therefore, i t i s a n t i c i p a t e d t h a t t he p r o t o t y p e u n i t w i l l work e f f i - c i e n t l y as a c u r r e n t source over a wide range o f c o n d i t i o n s . However,

t h e c h a r a c t e r i s t i c s o f t h e p ro to type u n i t t h a t w i l l ensure e f f i c i e n t

d i s p e r s a l o f an atmospheric fog o f g i ven p r o p e r t i e s a r e s t i l l n o t known.

I n p a r t i c u l a r , t he optimum water d r o p l e t s i z e i s unknown. P a r t o f t he

u n c e r t a i n t y r e s u l t s f rom a l a c k o f knowledge o f how a fog i s d ispersed

by t h e charged d rop le ts .

cence and subsequent movement i n the g r a v i t a t i o n a l f i e l d t o t h e ground

[9,10] o r t h e d r o p l e t s cou ld t r a n s f e r p a r t o f t h e i r charge t o t h e fog

p a r t i c l e s causing them t o f o l l o w t h e e l e c t r i c f i e l d t o t h e ground [30].

Also, i t i s p o s s i b l e t h a t on l y some coalescence i s r e q u i r e d t o inc rease t h e v i s i b i l i t y through the f o g w i t h o u t p r e c i p i t a t i o n . D i f f e r e n t mecha-

nisms q u i t e p o s s i b l y cou ld be i nvo l ved i n f o g d i s p e r s a l i n d i f f e r e n t

types o f fogs. These quest ions must be addressed i n a f u l l f i e l d t e s t

o f a group o f p ro to type u n i t s .

which c r e a t e a n e a r l y un i fo rm e l e c t r i c f i e l d d i s t r i b u t i o n i n t h e h o r i - zon ta l d i r e c t i o n w i l l f u l l y v e r i f y t he two-dimensional f o g d i s p e r s a l

t h e o r i e s [30]. performance r e s u l t s f rom t h e p ro to type u n i t . Thus, t he more complete

f i e l d t e s t s should be performed o n l y a f t e r complete examinat ion o f t he

s i n g l e u n i t t h a t i s descr ibed i n Sec t i on 4.0.

The concepts used f o r t h e

It i s p o s s i b l e t h a t i t i s d ispersed by coales-

Only a s u f f i c i e n t l y l a r g e group o f u n i t s

The number o f u n i t s t o be used i s dependent on t h e

27

REFERENCES

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4.

5.

6.

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8.

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11.

Christensen, Larry S., and Walter Frost: CR-3255 , March , 1980.

"Fog Dispersion," NASA

Frost, Walter, Frank G. Collins, and David Koepf: "Charged Particle Concepts for Fog Dispersion," NASA CR 3440, June, 1981.

Ruhnke, L. H.: "Warm Fog Modification by Seeding with Unipolar Ions," AMS Second National Conference on Weather Modification, Santa Barbara, California, pp. 385-388, 1970.

Juisto, J. E.: "Laboratory Evaluation of an Electrogasdynamic Fog Dispersal Concept," Federal Aviation Administration Report No. FAA-RD-72-99, 1972.

Chiang, T. K.: "Field Evaluation of an Electrogasdynamic Fog Dispersal Concept, Part I," Federal Aviation Administration Report No. FAA-RD-73-33, February, 1973.

Wright, T., and R. Clark: Fog Dispersal Concept, Part 11," Federal Aviation Administration Report No. FAA-RD-73-33, February, 1973.

"Field Evaluation of an Electrogasdynamic

Clark, R. S. , et a1 .: "Project Foggy Cloud V: Panama Canal Warm Fog Dispersal Program," Naval Weapons Center Report NWC TP 5542, December, 1973.

Carroz, John W., and Patrick N. Keller: "Electrostatic Induction Parameters to Attain Maximum Spray Charge to Clear Fog," Naval Weapons Center Report NWC TP 5796, January, 1976.

Tag, Paul M.: Electrically Enhanced Coalescence: Part I. An Applied Electric Field," Journal of Applied Meteorology, Vol. 15, pp. 282-291, 1976.

Tag, Paul M.: Electrically Enhanced Coalescence: Part 11. Charged Drop Seeding," Journal of Applied Meteorology, Vol. 16, pp. 683-696, 1977.

Whitby, K. T.: "Generator for Producing Hiqh Concentrations of

"A NLmerical Simulation of Warm Fog Dissipation by

"A Numerical Simulation o f Warm Fog Dissipation by

Small- Ions," The Review of Scientific Instriments, Vol. 32, pp. 1351-1355, 1961.

28

72. Lawson, K a u r i c e I l l - . - lull GellelatiGi; by Coror,a Discharge f e r Electro-F1 u i d Dynamic Energy Conversion Processes , I ' Aerospace Research Laboratories Report ARL 64-76, October, 1964; Proceedings of the S i x t h AGARD Combustion and Propulsion Colloquium, March 16- 20, 1964, Cannes, France, pp . 603-612.

13. Kahn, Bernard, and Meredith C . Gourdine: "Elec t ros ta t ic Power

14. Marks, A . , E . Barreto, and C . K. Chu: "Charged Aerosol Energy

15. Marks, Alvin M. :

16. Hasinqei , Seiqfried: "Perforkance Character is t ics of Electro-

Generation," AIAA Journal, Vol. 2 , pp . 1423-1427, 1964.

Convecter," AIAA Journal , Vol . 2 , pp. 45-51 , 1964.

Journal of App l i ed Physics, Vol. 43, pp. 219-230, 1972. "Optimum Charged Aerosols f o r Power Conversion,"

1 -

Ball i s t i c Generators," Proceedings of the S i x t h AGARD Combustion and Propulsion Colloquium, March 16-20, 1964, Cannes, France, p p . 581 -601.

17. Lawson, Maurice 0.: "Performance Character is t ics of Electro-Fluid Dynamic Energy Conversion Processes Employing Viscous Coupling," Proceedings of the S i x t h AGARD Combustion and Propulsion Collo- q u i u m , March 16-20, 1964, Cannes, France, pp. 563 - 580.

18. Wegener, P . P . , and L . M . Mack: "Condensation i n Supersonic and Hypersonic Wind Tunnels," Advances i n Applied Mechanics , Vol . 5, H . L . Dryden and T. von Karman (ed i to r s ) . New York: Academic Press, 1958.

19. Moses, C . A . , and G . D . Stein: "On the G r o w t h of Steam Droplets Formed i n a Lava1 Nozzle Usinq Both S t a t i c Pressure and L i q h t Scat ter ing Measurements, I ' Transactions of the ASME , Journai of Fluids Engineering, Vol. 100, pp . 311-322, 1978.

20. Barreto, Ernesto: "On the Formation of Langevin Ions i n Water Supersaturated Air J e t s , " Final repor t , ONR Contract Nonr-4890(00) , AD670551 , 1968.

21. Lawson, Maurice 0 . : Private communication, December 18, 1980.

22 . Howartson, A. M . : An Introduction t o Gas Discharges. New York: Pergamon Press, 1965.

23. Loeb, Leonard B . : Electrical Coronas, Their Basic Physical Mechanisms. Berkeley, California: University of California Press, 1965.

24. Goldman, M . , and A . Goldman: "Corona Discharges," Chapter 4, Gaseous Electronics, Vol. 1 , Merle M. Hirsh and H . J . Oskam (ed i to r s ) . New York: Academic Press, 1978.

29

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Decaire, John A.: "Effects of Electrode Geometry-Similarity and Scaling Laws in EFD Energy Conversion Processes, I. Fundamental Considerations," AGARDograph 122, Selected Topics in Electro- fluid Dynamic Energy Conversion, December, 1968.

Minardi, 3 . E.: "Computed Performance Characteristics of Electro- fluid Dynamic Colloid Generators," Transactions of the ASME, Journal of Engineering for Power, pp. 183-191, April, 1971.

Hamza, Vladimir, and Edward A. Richley: "Numerical Solution of Two- Dimensional Poisson Equation: Theory and Application to Electrostatic-Ion-Engine Analysis," NASA TN D-1323, October, 1962.

Hamza, Vladimir: "Numerical Solution of Axially Symmetric Poisson Equation: TN D-1711, May, 1963.

Bogart, Carl , D. , and Edward A. Richley: "A Space-Charge-Flow Computer Program," NASA TN D-3394, April , 1966.

Theory and Application to Ion-Thrustor Analysis," NASA

Gourdine, M. C., T. K. Chiang, and A. Brown: "A Critical Analysis of the EGD Fog Dispersal Technique," The Cornel1 Engineer, pp. 14- 34, November, 1975.

Gourdine, Meredith C.: Private communication, June 25, 1980.

Malan, D. J., and B. F. J. Schonland: "An Electrostatic Fluxmeter of Short Response-Time for Use in Studies of Transient Field- Charges," Phys. SOC. Proceedings, Section B y Vol. 63, pp. 402-408, 1950.

Mapleson, W. W., and W. S. Whitlock: "Apparatus for the Accurate and Continuous Measurement of the Earth's Electric Field," Journal of Atmospheric and Terrestrial Physics, Vol. 7, pp. 61-72, 1955.

Gathman, Stuart G., and Robert V. Anderson: for Electrostatic Measurements," The Review of Scientific Instruments, Vol. 36, pp. 1490-1493, 1965.

Anderson, R. B. : "Measuring Techniques," Lightning, Vol. 1 , Chapter 13, R. H. Golde (editor). New York: Academic Press, 1977.

"Improved Field Meter

Chalmers, 3. Alan: Atmospheric Electricity, 2nd edition. New York: Pergamon Press, 1967.

30

APPEND1 X

BIBLIOGRAPHY OF W RK RELATE

APPENDIX

TO ELECTROFLU D DY IAMIC POWER GENERATIO

1.

2.

3.

4.

5.

6.

7.

8.

9.

10.

Bogart, Carl D., and Edward A. Richley: Computer Program," NASA TN D-3394, April , 1966.

Decaire, John A.: Scaling Laws in EFCl Energy Conversion Processes, I. Considerations," AGARDograph 122, Selected Topics in Electrofluid Dynamic Energy Conversion, December, 1968.

Hamza, Vladimir, and Edward A. Richley: "Numerical Solution of Two-Dimensional Poisson Equation: Theory and Application to Electrostatic-Ion-Engine Analysis," NASA TN D-1323, October, 1962.

Hamza, Vladimir: "Numerical Solution of Axially Symmetric Poisson Equation: Theory and Application to Ion-Thrustor Analysis," NASA TN D-1711, May, 1963.

"A Space-Charge-Flow

"Effects of Electrode Geometry-Similarity and Fundamental

Hasingei, Siegfried: Ballistic Generators," Proceedings of the Sixth AGARD Combustion and Propulsion Colloquium, March 16-20, 1964, Cannes, France,

Hawes, M.: "Experimental Techniques in Electrofluid Dynamic Energy Conversion Research," Proceedings o f the Sixth AGARD Combustion and Propulsion Colloqu%m, March 16-20, 1964, Cannes, France, pp. 613-630; Aerospace Research Laboratories Report ARL 64-77 , October , 1964.

"Performance Characteristics of Electro-

pp. 581-601.

Kahn, Bernard, and Meredith C. Gourdine: Generation," AIAA Journal, Vol. 2, pp. 1423-1427, 1964.

Lawson, Maurice 0.: Dvnamic Enerqv Conversion Processes Employing Viscous Coupling,"

"Electrogasdynamic Power

"Performance Characteristics of Electro-Fluid . .

PFoceedings 6? the Sixth AGARD Combustion and Propulsion Colloquium, March 16-20, 1964, Cannes, France, pp. 563-580.

Lawson, Maurice 0.: Electro-Fluid Dynamic Energy Conversion Processes , I ' Aerospace Research Laboratories Report ARL 64-76, October, 1964; Proceedings of the Sixth AGARD Combustion and Propulsion Colloquium, March 16- 20, 1964, Cannes, France, pp. 603-612.

Marks, A., E. Barreto, and C. K. Chu: "Charged Aerosol Energy Convecter," AIAA Journal, V o l . 2, pp. 45-51, 1964.

"Ion Generation by Corona Discharge for

32

I ? . Marks , A l v i n M. : "Optimum Charged P,er!Xe!s f e r Pewer Ccnversicn," Journa l o f App l ied Physics, Vol . 43, pp. 219-230, 1972.

12. M ina rd i , J. E. : "Computed Performance C h a r a c t e r i s t i c s o f E l e c t r o - f l u i d Dynamic C o l l o i d Generators," T ransac t ions o f t h e ASME, Journa l o f Engineer ing f o r Power, pp. 183-191, A p r i l , 1971.

13. M ina rd i , J. E. , and M. 0. Lawson: "Research Progress on t h e E l e c t r o f l u i d Dynamic Wind Generator," Paper presented a t S E R I Second Wind Energy Innovat ive Systems Conference, December 3-5, 1980, Colorado Spr ings, Colorado.

14. S tue tzer , Otmar M.: " I o n Drag Pressure Generation," Journal o f App l ied Physics, Vol. 30, pp. 984-994, 1959.

15. S tue tzer , Otmar M.: " I o n Transpor t High Vol tage Generators," The Review o f S c i e n t i f i c Instruments, Vol. 32, pp. 16-22, 1961.

16. W i l l ke , Theodore L.: "Current Produc t ion i n a C y l i n d r i c a l Geometry E l e c t r o f l u i d Dynamic Generator," Aerospace Research Labora to r ies Report ARL 71-0245, October, 1971.

17. W i f a l l , James R.: "E f fec ts o f E lec t rode Geomet ry -S imi la r i t y and Sca l i ng Laws i n EFD Energy Conversion Processes, 11. Experimental Results,' ' AGARDograph 122, Selected Topics i n E l e c t r o f l u i d aynamic Energy Conversion, December, 1968.

33

TECHNICP 1. REPORT NO. 2. GOVERNMENT ACCESSION NO.

NASA CR-3481

19. SECURITY C L A S S I F . (of thln repOCI)

0. T I T L E AND S U B T I T L E

DESIGN OF PROTOTYPE CHARGED PARTICLE FOG DISPERSAL UNIT

20. SECURITY CLA

7. AUTHOR(S) Frank G . Collins, Walter Frost, and Philip Kessel

Unc 1 ass i f i ed Uncl a ss i f i ed

9. PERFORMING ORGANIZATION NAME AND ADDRESS

FWG Associates, Inc.

Tu1 1 a homa , Tennessee 37388 R . R . 2 , BOX 271-A

12. SPONSORING AGENCY NAME AND ADDRESS

National Aeronautics and Space Administration Washington, D . C . 20546

40 A0 3

1 5 . SUPPLEMENTARY NOTES

Marshall Technical Monitor: Dennis W . Camp Final Report

REPORT STANDARD TITLE PAGE 3. R E C I P I E N T ' S CATALOG NO.

5. REPORT DATE

December 1981 6. PERFORMING ORGANIZATION CODE

8 . PERFORMING ORGANIZATION REP OR^ B

0. WORK UNIT. NO.

M-364 11. CONTRACT OR GRANT NO.

NAS8-33541 13. TYPE O F REPORi' & PERIOD COVEREC

Contractor Report

1 4 . SPONSORING AGENCY CODE

16, ABSTRACT

A prototype charged par t ic le fog dispersal unit was designed, and drawings of the u n i t are included. par t ic le fog dispersal techniques and on electrofluid dynamic energy conversion devices was incorporated i n t o the design. fied so t h a t certain features t h a t influence the output current a n d par t ic le s ize distribution could be examined. An experimental program was designed t o measure the performance of the u n i t . The program includes measurements i n a fog chamber and in the f i e l d . m u s t be measured.

Experience gained by previous investigators on charged

The u n i t was designed to be easi ly modi-

U n i t performance parameters plus external e lec t r ic f ie ld quantit ies

17. KEV WORDS

Fo 9 Fog Dispersal Visibi l i ty Ceilings C1 oud Physics

18. D I S T R I B U T I O N S T A T E M E N T

Unclassified - Unlimited

Subject Category 47 2 1 . NO. OF PAGES 22. P R I C E IF. (of thl. wee)