PHASE DOPPLER MEASUREMENTS OF LIQUID AGENT 

TRANSPORT OVER A HEATED CYLINDER 

C. Presser*, C.T. Avedisian‡, and B.S. Johnson*

*

 National Institute of Standards and Technology 

Gaithersburg, MD 20899-8360, USA 

cpresser@nist.gov 

‡

Cornell University 

Ithaca, NY 14853, USA 

cta2@cornell.edu 

ABSTRACT 

Experimental results are presented for a well-characterized, droplet-laden homogenous 

turbulent flow field around a cylindrical obstacle. Liquid agent transport was 

investigated around an unheated and heated cylinder under ambient conditions. Results 

for water are reported in this investigation. For the heated case, the cylinder was heated 

initially to a near-surface temperature of approximately 423 K. Phase Doppler 

interferometry and visualization techniques were used to explore the thermal effects on 

droplet surface impingement, vaporization, and transport around and downstream behind 

the cylinder, by providing information of droplet size and velocity in the vicinity of the 

cylinder. Results indicated that impinging droplets generally coat the surface with few 

droplets rebounding back into the free stream. Downstream in the wake region of the 

cylinder, smaller size droplets (generally, of less than 30 μm) are entrained into the 

recirculation zone. Near the heated cylinder surface, thermal effects reduce droplet mean 

size significantly. 

INTRODUCTION 

The next generation of non-ozone-depleting Halon alternatives include chemical 

suppressants that have high boiling point temperatures (i.e., Tb > 330 K) and exist in the 

liquid phase under high-pressure release or in ambient conditions. Release of these 

agents in a confined cluttered space results in the dispersal of droplets that either travel 

along ballistic trajectories, move with the convecting flow, or impact upon nearby solid 

obstacles. An accurate representation of droplet transport is crucial for the numerical 

modeling of fire suppression in confined spaces using these agents. To better understand 

the physics of droplet transport around and behind solid objects, an experimental spray 

facility was modified to impose controlled grid-generated turbulence on the air stream. 

From this facility, droplet size and velocity data were obtained for a well-characterized, 

homogenous droplet-laden turbulent flow field around prescribed obstacles. This 

experimental effort compliments a numerical effort to develop and validate the subgrid 

model of the VULCAN computational fluid dynamics (CFD) fire physics code for sprayclutter interactive environments, under development at Sandia National Laboratories [1]. 
In an earlier investigation, the turbulent flow over cylinders of different diameters at 

ambient conditions was investigated to provide a baseline flow field characterization of 

geometric effects on the separated flow past the cylinder [2]. The results of this earlier 

investigation were then expanded to study droplet transport over a cylinder that was 

preheated to 423 K, well above the boiling point of the agent, for the same turbulent flow 

conditions [3]. In these two previous studies, particle image velocimetry was used to 

obtain the two-dimensional velocity field of the gas stream and droplets. The results of 

this study indicated that smaller droplets are entrained into the recirculation region behind 

the cylinder while the larger droplets impact the cylinder surface, accumulate and drip 

off, rebound off the surface and disperse radially outward into the free stream, and/or are 

entrained in the free stream and transported around the surface. The flow over the heated 

cylinder indicated the formation of a vapor layer on the downstream side of the cylinder 

in the shear region between the recirculation zone and free stream. Vaporization of 

smaller droplets near the heated cylinder surface suggested an increased probability of 

vapor, and reduced probability of droplet entrainment into the cylinder wake region. 

The results of these earlier studies indicated that droplet surface impact, vaporization, and 

transport behind the cylinder were dependent on droplet size. Thus, this work focuses on 

measurement of spatially and temporally resolved droplet size and velocity distributions 

in the upstream and downstream vicinity of the cylinder, using phase Doppler 

interferometry (PDI). Water was used as the liquid agent, with two additional agents, 

3MTM fire protection fluorocarbons HFE-7100 (with a boiling point of 334 K) and HFE7000 (with a boiling point of 307 K) to be used at a later date. Several strategies may be 

used to detect size dependent effects in regions where droplets rebound or vaporize. For 

example, a droplet near the upstream surface of the cylinder with a negative streamwise 

velocity (i.e., a droplet transported against the flow) would be indicative of a droplet 

rebounding off of the cylinder surface, and thus PDI would be used to obtain the 

associated droplet size. If the size distribution near the heated cylinder surface is devoid 

of relatively smaller size droplets, as compared to other locations away from the cylinder,

then this result may be indicative of the effects of vaporization. These ideas were used in 

interpretation of the measurements. 

EXPERIMENTAL SETUP 

TEST FACILITY 

A schematic of the test facility is shown in Fig. 1. The facility is oriented so that the flow 

issues horizontally to allow for the collection of liquid agent that drips off the cylinder, 

and prevent liquid droplets downstream of the obstacle from falling back upstream into 

the oncoming flow. The agent used in the present study was water, supplied through a 

60° solid-cone, pressure-jet atomizer with a higher concentration of droplets in the center 

of the spray cone (Delavan∗

 type R-D nozzle with a nominal flow rate of 3.0 kg/h at 

 

∗ Certain commercial equipment or materials are identified in this publication to specify

adequately the experimental procedure. Such identification does not imply recommendation or 

endorsement by the National Institute of Standards and Technology, nor does it imply that the 

materials or equipment are necessarily the best available for this purpose. 

2
atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

atomizer

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

air

liquid

agent

honeycomb

gr distributor id

spray

heated obstacle

plexiglas chamber

collector

collector (pan)

exhaust

seeding

agent

Figure 1. Schematic of the experimental arrangement for the droplet-laden, gridgenerated turbulent flow field. 

791 kPa). An octagon-shaped Plexiglas insert (with a wall thickness of 6 mm, length of 

610 mm, and major and minor axes of 760 mm and 560 mm) was used as a boundary 

condition. The Plexiglas insert, along with the front face that supported the inlet passages 

for the liquid agent and air, and back face that supported the exhaust passage, served to 

form a closed system. A honeycomb layer (51 mm thick with 3 mm size cells) was used 

to straighten the airflow, which was co-positioned around an injector for the agent (see 

Fig. 2). Grid generated turbulence was imposed on the air stream by placing a square 

layer of wire mesh screen (with dimensions of 229 mm width by 330 mm length, 3.2 mm 

wire thickness, and 13 mm size cells) downstream of the honeycomb. The rationale for 

this arrangement is given elsewhere [2,3]. For the present experiments, the incoming air 

(supplied at 265 kg/h) was directed entirely through a distributor plate with steel wool, 

the circular cross-sectional area of the honeycomb (203 mm in diameter), and then 

through the wire mesh screen (placed 25 mm downstream of the honeycomb), as shown 

in Fig. 1. The face of the liquid atomizer was placed flush with the upstream side of the 

grid, and centered within one mesh cell so that the liquid spray would be unimpeded by 

the grid. Figure 2 presents a photograph of this arrangement. The integral and 

Kolmogorov length scales of turbulence were estimated to be approximately 3 cm and 

100 μm, respectively. A stepper-motor-driven traversing system translated the entire 

assembly, and permitted measurements of the flow field properties at selected locations 

downstream of the injector and around the obstacle. 

OBSTACLE CHARACTERISTICS 

The obstacle was an aluminum cylinder with a diameter of approximately 29.2 mm and a 

length of 305 mm (see Fig. 3). Its diameter was larger than the integral length scale of

turbulence. A hole (13 mm in diameter) was bored through the center to accommodate 

3
Figure 2. Photograph of liquid atomizer placement in relation to honeycomb and 

wire mesh screen. 

a 250 W cartridge heater (13 mm in diameter and 76 mm in length). The rod was cut 

along its axis into two halves, and 1 mm deep channels were bored along one segment to 

accommodate five K-type thermocouples. The thermocouples had an Inconel sheath, 

were ungrounded, and were 0.8 mm in diameter (305 mm long). The thermocouples 

were placed in a cross pattern in the center of the rod (each separated by a distance along 

the surface of 6.4 mm, with the thermocouple junctions placed about 3.2 mm of the 

surface from within bored holes at each location). The central thermocouple was used for 

temperature control of the heater, which was positioned behind the thermocouples. 

PHASE DOPPLER INTERFEROMETER 

Since its introduction, phase Doppler interferometry (PDI) [4,5] has been used to 

characterize sprays in areas such as liquid fuel spray combustion, coal slurry combustion, 

coatings, pesticides, fire suppression, and others. PDI is an extension of laser Doppler 

velocimetry that measures droplet size as well as velocity. Phase Doppler techniques 

involve creating an interference pattern in the region where two laser beams intersect, and 

results in a region consisting of alternating light and dark fringes. The region where the 

laser beams intersect is called the probe volume or sample volume. Due to the 

interference pattern, a droplet passing through the probe volume scatters light that 

exhibits an angular intensity distribution, which is characteristic of the size, refractive 

index, and velocity of the droplet. For a droplet with known refractive index, the size and 

velocity can be determined by analyzing the scattered light collected with several 

photomultiplier tubes. 

The PDI is a single-point (or spatially resolved) diagnostic instrument in that it obtains 

information about the spray at a single point in space. Only by moving the probe volume 

4
76 mm

29 

Figure 3. Schematic and photograph of the cylinder with installed cartridge heater 

(or, equivalently, the spray) can one map out the spatial distribution of the spray 

characteristics. The PDI is also a single-particle instrument in that information is 

obtained for only one droplet at a time. This offers advantages over integrating 

techniques because the characteristics of a particular droplet (size, velocity, etc.) can be 

recorded and the data can be separated into classes (size classes, velocity classes) to 

further characterize the spray system. 

The experiments were conducted using a 2-component phase Doppler interferometer with 

a Real-time Signal Analyzer (RSA) available from TSI, Inc. This PDI system is 

composed of the following components: (i) transmitter (model XMT204-4.3), (ii) fiber 

drive (model FBD240-X), (iii) receiver (model RCV216-X), (iv) Real-time signal 

processors (models RSA3200-P and RSA3200-L), (v) PMT box (model RCM200P), and 

(vi) RSA IO card v.3.0 (model RSA3CB2DV3). The PDI was controlled using TSI 

DataVIEW software version 2.02 run on a personal computer using the Windows NT 

operating system. The RSA has the ability to optimize the number of samples acquired 

from the Doppler signal in real-time. A 5 W argon ion laser operating in multi-line mode 

was used as the illumination source. The blue (wavelength = 488 nm) and green 

(wavelength = 514.5 nm) lines of the argon ion laser were separated by beam

5
conditioning optics, and focused by the transmitting optics to intersect and form the probe 

volume. The transmitting optics are coupled to the beam conditioning optics using fiber 

optic cables to permit the transmitter to be located near the experiment. The front lens on 

the transmitter has a focal length of 500 mm. The green and blue beams have a beam

separation distance of 39.9 mm and 40.2 mm, fringe spacing of 6.45 μm and 6.07 μm,

and beam waist of 164 μm and 155 μm, respectively. Frequency shifting is set at 

PDI receiver / 

mirror

PDI 

transmitter

experiment 

560 mm

760 mm

PDI transmitter

PDI receiver

Plexiglas chamber

Heated cylinder

Grid / atomizer /

honeycomb

θ

560 mm

760 mm

PDI transmitter

PDI receiver

Plexiglas chamber

Heated cylinder

Grid / atomizer /

honeycomb

560 mm

760 mm

PDI transmitter

PDI receiver

560 mm

760 mm

PDI transmitter

PDI receiver

Plexiglas chamber

Heated cylinder

Grid / atomizer /

honeycomb

θ

Figure 4. View and schematic of the experimental arrangement with the laser from 

the phase Doppler interferometry system 

6
40 MHz. The receiver was located at a scattering angle, θ, of 30o

 measured from the 

direction of propagation of the laser beams. To accommodate the horizontal orientation 

of the experimental apparatus, the transmitter and receiver are positioned in a vertical

plane, as shown in Fig. 4. Due to the large size of the receiver, the transmitter is 

positioned with the laser beams angled at 30o

 to the cylinder, which requires correction of 

the cross-stream velocity. The front lens on the receiver had a focal length of 1000 mm. 

The spacing for the three PMT detectors (A, B, and C) that are used to carry out the sizing 

measurements was 34.8 mm for detectors A and B, and 101 mm for detectors A and C. A 

150 μm slit aperture is located within the receiver to limit the length of the probe volume. 

The signal processor was operated with the following settings: sample frequency of 

40 MHz (the rate at which the Doppler signal is sampled), mixer frequency of 36 MHz 

(mixers are used to reduce the signal frequency prior to analog-to-digital conversion), and 

a low pass filter setting of 20 MHz (low pass filters are used to remove the summed 

components from the downmixed signal, so that only the difference is used). The settings 

result from optimizing the processor for the expected Doppler frequency, which is 

governed by the droplet velocity and fringe spacing. Hardware coincidence, which 

requires that droplets be detected on both PDI channels simultaneously to be validated, 

was used as an additional validation criterion for all measurements. Intensity validation 

(to remove particles whose scattered light intensities are too low and high, and result in 

erroneous phase shifts and particle sizes), and probe volume corrections (to account for 

droplets of varying size traveling through different sections of the Gaussian beam profile) 

were carried out to optimize the quality of the measurements. The measurements were 

carried out at several radial (R, cross-stream) positions and over a range of axial (Z, 

streamwise) positions upstream and downstream of the cylinder. Figure 5 illustrates the 

measurement grid that was used and the location of the cylinder relative to the grid mesh. 

Measurements were carried out from approximately 50 mm upstream of the cylinder to a 

downstream position of 100 mm. An increment of 2.5 mm was used for –25.4 mm < Z < 

38.1 mm, and an increment of 12.7 mm for all other axial positions. In the radial 

direction, measurements were carried out in increments of 5 mm from 0 to 20 mm in the 

upper hemisphere (i.e., in the positive radial direction). 

7
Figure 5. Schematic of the measurement grid around the cylinder 

R

Z

182 mm

RESULTS AND DISCUSSION 

EXPERIMENTAL OBSERVATIONS 

In our earlier investigation [3,6], the droplet-laden flow field over both the unheated and 

heated obstacle was recorded with a high-resolution digital camera (providing both stillimages and movies at 9 frames/s). Droplets were observed in the center of the spray 

impinging on the surface of the cylinder and dripping off at the bottom of the cylinder,

while those droplets at larger radial positions were transported around the cylinder. 

Movies obtained with a high-speed digital camera at 1000 frames per second indicated 

that many impinging droplets rebounded off of the surface and into the free stream. More 

rebounding droplets were observed when the air velocity was zero. Few larger size 

droplets were observed behind the cylinder in its wake, but were abundant with smaller 

size aerosol droplets that were introduced to the flow through the air stream. There was 

no evidence of secondary breakup of the droplets, which was expected because the Weber 

number was much smaller than the critical value for droplet shattering. 

When the cylinder was heated to 423 K (i.e., well above the boiling point of water), the 

droplet-laden flow over the cylinder appeared to be similar to the unheated case except 

along the shear layer downstream of the cylinder. In this region, a vapor layer formed 

which was presumed to be the result of vaporization of the liquid that wets the hot 

surface. It was expected that vaporization of liquid near the cylinder surface may 

influence locally the transport of droplets behind the cylinder by vaporizing the smaller 

size droplets, and thus was a focus of the current investigation.

In this study, a solid-cone nozzle was used to increase the number of droplets impinging 

on the cylinder surface (a hollow-cone atomizer was used in our previous work). It was 

observed that drippings off the cylinder occurred at a rate of approximately 6.5 mL/min 

for the unheated cylinder, while there was no dripping for the heated cylinder due to 

droplet vaporization. It was also observed by the PDI laser beams, as shown by the 

8
Figure 6. Illumination of the phase Doppler laser beams behind the cylinder 

reduced intensity around the beam probe volume in Fig. 6, that the concentration of 

droplets behind the cylinder was significantly reduced. For the heated cylinder, the 

cylinder surface temperature varied significantly with time after the spray was introduced 

to the flow field. However, it is unknown at this time whether these changes are 

attributable to time-varying changes in the response time of the cylinder heater during 

droplet impingement, or to some other systemic problem. 

DROPLET SIZE AND VELOCITIES MEASUREMENTS

The PDI was used to provide information on: 1) droplets rebounding off the upstream 

face of the cylinder, 2) vaporization of droplets near the heated cylinder, and 3) the 

droplet sizes that are entrained into the recirculation region behind the cylinder. The 

unheated cylinder results for the Sauter mean diameter (D32) and droplet mean 

streamwise component of velocity (U) are presented in Fig. 7. Note that measurements 

were carried out to check the spray symmetry over the cylinder. The rectangle located on 

the abscissa at an axial position of Z ≅ ± 14.6 mm represents the location of the cylinder. 

The expanded uncertainty for D32 is 3.8 μm, and for U is 0.35 m/s, calculated as 2uc 

(representing a level of confidence of 95 %), where uc is calculated as the largest standard 

deviation of the mean (among standard deviations of the mean based on two replicates at 

each measurement location) throughout the measurement domain. The gap in the data for 

the radial positions R = 0, 5, and 10 mm indicates the presence of the cylinder. For Fig. 

7A, the general trends are: 1) a decrease in mean size on the downstream side of the 

cylinder, as compared to the upstream side, and 2) an increase in mean size with 

increasing radial distance from the central plane of the cylinder. The latter is indicative 

of the presence of more smaller size droplets near the center of the spray, in particular at 

Z = -50 mm, which is attributed to the design characteristics of the atomizer. For the 

droplet mean streamwise velocity (see Fig. 7B), the values increase with decreasing 

radial position at the upstream position of Z = -50 mm. These higher velocities correlate 

with the smaller droplet mean size near the center of the spray. As the droplets approach 

9
the upstream surface of the cylinder, there is a decrease in the streamwise velocity 

component and an increase in the cross-stream component (data not shown). There is an 

A B

Figure 7. Variation of droplet A) Sauter mean diameter and B) mean streamwise velocity 

with streamwise position at different cross-stream positions for the unheated cylinder. 

A B

Figure 8. Variation of the streamwise velocity with time at two streamwise positions

of A) Z = 25 mm and B) Z = 76 mm along the centerline, downstream of the 

unheated cylinder within the recirculation region 

increase in the droplet streamwise velocity over the cylinder for R = 15, and 20 mm, 

which was also characteristic of the accelerated flow detected in our earlier PIV 

investigation [3,6]. At locations near the upstream surface of the cylinder, negative 

values for the streamwise velocity are detected (data not shown), which may be indicative 

of droplets rebounding off of the surface. However, positive values of velocity are 

obtained for the abundance of droplets, which indicates that these impinging droplets 

either adhere to the cylinder surface or rebound at an angle that maintains their 

momentum in the downstream direction over the cylinder. The droplet streamwise 

velocities decrease and become negative values for R = 0, 5, and 10 mm on the 

downstream side of the cylinder, which is indicative of the presence of a recirculation 

zone and the entrainment of these droplets into this zone. Data were not obtained 

immediately downstream of the cylinder (i.e., for ≈ 25 mm < Z < 14.6 mm) because the 

signals were too low to detect any droplets. 

10
Although the magnitude of the droplet mean streamwise velocity downstream of the 

cylinder is negative, indicating the presence of a recirculation region, it is clear that the 

mean is representative of a distribution of velocities and associated droplet sizes. This 

point is highlighted in Fig. 8, which presents the droplet streamwise velocity with respect 

to droplet interarrival time into the probe volume at two points downstream of the 

cylinder within the recirculation region. One measurement location along the centerline, 

at Z = 25 mm, represents a measurement close to the cylinder, while the other, at 

Z = 76 mm (see Fig. 8B), represents a location near the downstream edge of the 

recirculation pattern. The results for Z = 25 mm (see Fig. 8A) indicate that many droplets 

are recirculated upstream toward the cylinder (because U < 0), as expected, but also 

indicate that several droplets at this location are transported in the downstream direction 

(i.e., U > 0). One can speculate that these latter droplets either originate in the 

recirculation zone or are transported around the cylinder surface and penetrate directly 

into the recirculation region. The cross-stream velocity component indicates that both 

positive and negative values are obtained for this group of droplets. In addition, the 

droplet size does not provide additional information since the size for these droplets 

varies between 5 μm and 30 μm, and this range is similar to that for the size distribution 

for the entire population for this measurement. In a similar vane, the results in Fig. 8B 

indicate that the abundance of droplets are transported in the downstream direction at this 

point (i.e., for U > 0). However, a few droplets are entrained into the recirculation region 

(i.e., for U < 0). 

Comparison of results for the unheated and heated cylinders indicates consistently that 

the droplet Sauter mean diameter, D32, is smaller for the heated case as the droplets are 

transported past the cylinder surface. The droplet streamwise and cross-stream

components of velocity are also lower for the heated case. The unheated and heated 

results are compared in Fig. 9 for D32 and U at R = 20 mm. The decrease in the values of 

both D32 and U for the heated case indicates that droplet vaporization does not result in 

the complete removal of the smaller size droplets from the distribution, but instead a 

decrease in the size of all droplets (which results in an overall decrease in both the mean 

size and velocity). In fact, the droplet size distributions illustrate clearly the shift of the 

entire distribution to smaller sizes for the heated cylinder. An example of this change in 

the size distributions is given in Fig. 10 at R = 20 mm and Z = 0. 

11
A B

Figure 9.Variation of droplet A) Sauter mean diameter and B) mean streamwise 

velocity for the unheated and heated cylinders 

Figure 10. Droplet size distribution for both the unheated and heated 

cylinder at R = 20 mm and Z = 0 

CONCLUSIONS 

Phase Doppler measurements were carried out to obtain droplet size and velocity 

distributions in a droplet-laden homogenous turbulent flow field around a cylindrical 

obstacle. Results indicated that most impinging droplets coat the surface with few 

droplets rebounding back into the free stream. Rebounding droplets are generally less 

than 30 μm, corresponding to the higher probability portion of the size distribution. 

Downstream in the wake region of the cylinder, a distribution of smaller size droplets 

(generally, of less than 30 μm) is entrained in the recirculation zone. Near the heated 

cylinder surface, droplet vaporization results in smaller mean droplet sizes, as compared 

to the ambient case. 

12
ACKNOWLEDGEMENTS 

The authors wish to acknowledge the partial support of this research by the Department 

of Defense Next Generation Fire Suppression Technology Program, funded by the DoD 

Strategic Environmental Research and Development Program. The authors wish to thank 

J. Hewson, D. Keyser, P. Disimile, and J. Tucker of the NGP Project 6A/1 for the 

discussions and their guidance. We also wish to thank Dr. J.F. Widmann for his help in 

setting up the phase Doppler interferometer, and Mr. R. Fink for his technical assistance. 

REFERENCES 

1. DesJardin, P.E., Presser, C., Disimile, P.J., and Tucker, J.R., "A Droplet Impact Model for 

Agent Transport in Engine Nacelles," Proc. Halon Options Technical Working Conference 

(HOTWC-2002), New Mexico Engineering Research Institute, Albuquerque, NM, on CD, 

2002. 

2. Presser, C., Widmann, J.F., DesJardin, P.E., and Gritzo, L.A., "Measurements and Numerical 

Predictions of Liquid Agent Dispersal Around Solid Obstacles," Proc. 11th Halon Options 

Technical Working Conference (HOTWC-2001), New Mexico Engineering Research 

Institute, Albuquerque, NM, pp. 122-130, 2001. 

3. Presser, C., Widmann, J.F., and Papadopoulos, G., "Liquid Agent Transport Around Solid 

Obstacles," Proc. 12th Halon Options Technical Working Conference (HOTWC-2002), NIST

Special Publication 984 (R.G. Gann and P.A. Reneke, Eds.), NIST, Gaithersburg, MD, on 

CD, 2002. 

4. Bachalo, W.D., and Houser, M.J., "Development of the Phase/Doppler Spray Analyzer for 

Liquid Droplet Size and Velocity Characterizations," AIAA/SAE/ASME 20th Joint 

Propulsion Conference, Cincinnati, OH, June 1984. 

5. Bachalo, W.D., and Houser, M.J., "Phase/Doppler Spray Analyzer for Simultaneous 

Measurements of Droplet Size and Velocity Distributions," Optical Engineering, Vol. 23, pp. 

583-590. 

6. Presser, C., Papadopoulos, G., and Widmann, J.F., "Droplet_laden Homogeneous Turbulent

Flow past Heated and Unheated Cylinders," 4th ASME/JSME Joint Fluids Engineering 

Conference, Honolulu, HI, July 2003. 

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