* brown@erc-ltd.com, 949 583 1197 x 101

Nozzle Characterization:

Amerex Nozzle Droplet Size Classification

prepared for

Amerex

Christopher Brown*, Ulises Mondragon, Chris Antes, and Vincent McDonell

23342 South Pointe Drive, Suite E

Laguna Hills, CA 92653

Phone: (949) 583-1197

FAX: (949) 583-1198

10 December 2011

Report ERC-Amerex1-11-1(a)

Amerex PO Number SPS786

ENERGY

 RESEARCH

 CONSULTANTS
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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The recipient and reader of this report agrees to Hold Harmless Energy Plus Ltd doing 

business as Energy Research Consultants (ERC) and the Officers, Directors, Agents, 

and Employees from and against any and all liabilities and claims made by other 

individuals or entities as a result of using the information contained in this report. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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Table of Contents

1 Summary ............................................................................................................................ 1

2 Approach ............................................................................................................................ 1

2.1 Size Bins...................................................................................................................... 1

2.2 Probe Volume Correction............................................................................................. 1

2.3 Curve Fit ...................................................................................................................... 1

2.4 Other Comments on Approach..................................................................................... 2

3 Results................................................................................................................................ 5

3.1 Non Area Weighted Results......................................................................................... 5

3.2 Area Weighted Results ................................................................................................ 5

3.3 Comments on Results.................................................................................................. 5

4 Raw Data............................................................................................................................ 7

5 References ......................................................................................................................... 8

List of Figures

Figure 1. Measurement Locations............................................................................................. 2

Figure 2. Droplet Size Averages versus Radial Position For All Droplet Size Classes............... 3

Figure 3. Sample Log Normal Curve Fit. ................................................................................... 4

Figure 4. Area Weighting........................................................................................................... 6

Figure 5. Sample Raw Data. ..................................................................................................... 7

List of Tables

Table 1. Size Bins. .................................................................................................................... 2

Table 2. Size Classified Results by Number.............................................................................. 6

Table 2. Size Classified Results by Percent. ............................................................................. 6
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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1 Summary

This report summarizes the droplet size classification of previously obtained size 

data collected under a separate PO from Seal Seat. 

2 Approach

Droplet size data were previously obtained on two Amerex nozzles provided by 

Seal Seat. These measurements were collected under a separate PO from Seal Seat. 

Report number ERC-SealSeat2-11-1(a) in the Reference section provides additional 

details. 

2.1 Size Bins

Amerex requested the droplet sizes be classified using the size bins shown in 

Table 1. Four (4) radial locations at each of three (3) axial locations for a total of 12 

locations were sampled in the spray as is shown in Figure 1. The droplet counts 

obtained within a particular bin size were added up for all 12 locations. 

The previous average size results for all droplet size classes are shown in Figure 

2 for reference. 

2.2 Probe Volume Correction

Probe volume correction (PVC) was employed to compensate the measured size 

distribution for the smaller effective sample volume associated with the smaller drops

due to the Gaussian intensity profile of the laser beam. PVC represents the counts that 

would be obtained if all drop sizes had the same sample volume. 

2.3 Curve Fit

The lower theoretical detection limit of the phase Doppler instrument is 

approximately 0.5 microns. A log normal curve fit was applied to the data in order to 

estimate the counts below 0.5 microns. A sample fit is shown in Figure 3. Other curve 

fits were considered such as Rosin Rammler, but the log normal was found to best fit 

the number distribution, which is the distribution of interest to this analysis. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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2.4 Other Comments on Approach

Despite the approximate 0.5 micron lower detection limit, the phase Doppler 

instrument was the ideal choice to make these measurements within the available time 

and budget scopes. 

An additional radial location was sampled on the other side of the centerline was 

obtained at each axial location. These three (3) locations were not included in the 

calculation so as to not bias the results toward the center of the spray.

The budget for the current size classification did not allow for calculations on the 

second nozzle. The mean droplet sizes were similar (see report number ERCSealSeat2-11-1(a)), hence the size classified results are expected to be similar. 

Table 1. Size Bins. 

Left Side of Size Bin

(microns)

Right Side of Size Bin

(microns)

0.00 0.10

0.10 0.25

0.25 0.50

0.50 1.00

1.00 2.50

2.50 5.00

5.00 250.00

R, inches

Z, inches

-6 0 6 12 18 24 30 36 42

0

6

12

18

24

30

36

42

Nozzle Centerline

Figure 1. Measurement Locations. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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a) Nozzle 1

Distance from Centerline Y, inches

D10, microns

-6 -4 -2 0 2 4 6 8 10

0

20

40

60

80

100

120

140

160

180

200

220

240 Nozzle 1, Z = 12 inches Nozzle 1, Z = 18 inches Nozzle 1, Z = 36 inches

b) Nozzle 2

Distance from Centerline Y, inches

D10, microns

-6 -4 -2 0 2 4 6 8 10

0

20

40

60

80

100

120

140

160

180

200

220

240 Nozzle 2, Z = 12 inches Nozzle 2, Z = 18 inches Nozzle 2, Z = 36 inches

Figure 2. Droplet Size Averages versus Radial Position For All Droplet Size Classes. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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D, microns

Count

20 40 60 80 100

0

1000

2000

3000

4000

5000

6000

Corrected Count

Uncorrected Count

Log Normal Fit of Corrected Count

Log Normal Fit of Uncorrected Count

Figure 3. Sample Log Normal Curve Fit. 
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3 Results

The size classified results are summarized by number in Table 2 and by percent 

in Table 3. 

3.1 Non Area Weighted Results

Four (4) radial locations at each of three (3) axial locations for a total of 12 

locations were sampled in the spray as is shown in Figure 1. The droplet counts 

obtained within a particular bin size were summed up for all 12 locations. The total 

counts for each size bin are presented in Table 2 and percentages of the total count are

shown in Table 3. 

3.2 Area Weighted Results

The calculations were performed again with area weighting. Area weighting 

attempts to extend the results from a single radial profile to reflect the total spray. Area 

weighting weights the measurement at each radial position by the area which it 

represents, that is, r

2 weighting. Measurements from the center receive less weighting 

because they represent less area, measurements near the edge receive more weighting 

because they represent more area. See the sketch in Figure 4. The total counts for 

each size bin are presented in Table 2 and percentages of the total count are shown in 

Table 3. 

3.3 Comments on Results

Please keep the following considerations in mind when interpreting the present 

results. 

As noted above, the lower detection limit of the phase Doppler instrument is 

approximately 0.5 microns. A log normal distribution fit was applied to the data in order 

to estimate the counts in these lower size bins. 

The data were obtained in a spray chamber with approximately 1 m/s coflowing 

air in order to control droplet recirculation and prevent droplets from being measured 

twice. This is conventional practice. The coflowing air likely allows for significant 

evaporation of the very smallest droplets. Any droplets that evaporate prior to reaching 

the measurement volume are not measured. In practical conditions such as the 

confined space of a military vehicle, less evaporation would be expected and larger 

quantities of smaller particles may be found. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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Table 2. Size Classified Results by Number. 

Left Side

Size Bin

(microns)

Right Side

Size Bin

(microns)

Non Area Weighted

Number 

(count)

Area Weighted

Number 

(count)

0.00 0.10 7.2090E-20 1.2040E-14

0.10 0.25 1.8196E-14 1.3248E-09

0.25 0.50 2.0662E-10 8.2232E-06

0.50 1.00 8.4228E-07 0.03110774

1.00 2.50 0.00884 323.86607

2.50 5.00 7.26232 104,260

5.00 250.00 634,444 4,434,949,108

TOTAL 634,452 4,435,053,692

Table 3. Size Classified Results by Percent. 

Left Side

Size Bin

(microns)

Right Side

Size Bin

(microns)

Non Area Weighted

Number Percent

(%)

Area Weighted

Number Percent

(%)

0.00 0.10 1.1363E-23 2.7147E-22

0.10 0.25 2.8679E-18 2.9870E-17

0.25 0.50 3.2567E-14 1.8541E-13

0.50 1.00 1.3276E-10 7.0141E-10

1.00 2.50 1.3939E-06 7.3024E-06

2.50 5.00 1.1447E-03 2.3508E-03

5.00 250.00 99.9989 99.9976

TOTAL 100.00 100.00

Measurement Locations

Areas Represented By Each Measurement Location

(spray is flowing into page)

Figure 4. Area Weighting. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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4 Raw Data

Raw data in csv (comma separated value) format will be provided electronically. 

An example is shown in Figure 5. 

Size Bin

(microns)

Uncorrected Count Corrected Count

0.5 0 0

1.5 6 42

2.5 4 28

3.5 9 63

4.5 22 154

5.5 25 175

6.5 47 329

7.5 56 392

8.5 88 616

9.5 133 931

10.5 195 1365

etc etc etc

Figure 5. Sample Raw Data. 
Energy Research Consultants Droplet Size Classification Amerex PO number SPS786

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5 References

Nozzle Characterization: Droplet Sizing (Amerex Nozzles 1 and 2) (Summary Report), 

prepared for Seal Seat, Christopher Brown, Ulises Mondragon, Chris Antes, and 

Vincent McDonell, Energy Research Consultants, 15 September 2011, Report ERCSealSeat2-11-1(a), Seal Seat PO Number 7291871.