Effect of cross wind, nozzle angle and height on the performance of broadcasting spraying system.
Agricultural pesticide application system faces challenges and problems such as spray distribution and drift as result to the combinations of mechanical factors of spray technique (nozzle angle and height) and environmental variable(wind speed) and their interactions. Evaluation of the spray volumetric distribution of the nozzles is the most important issue in a spray analysis and had been studied by several researchers [1-4]. In order to achieve optimum spray distribution pattern above ground or plant level, nozzle angle is one of the most important variables that can be used in determining the nozzle height above ground or plant level. According to Byron and Hamey , Miller et al , and Spraying System CO , nozzle angle of 110[degrees] should be used with nozzle heights of less than 50 cm and have become an adopted standard that to give a uniform volume distribution pattern. The assessment of spray drift is necessary to reduce the pollution of ecosystem, but it is particularly complex and very difficult to repeat spray drift measurements in the field with a high degree of reliability because weather conditions cannot be controlled [8-9], which was the major reason to develop wind tunnel protocols for the measurement of spray drift in controlled conditions.
Spray drift for various conventional flat-fan nozzles was investigated and compared under laboratory conditions . Droplet size is an important factor for controlling spray drift to the non targeted areas. Reducing of the spray nozzle angle generally results in an increase in the droplet sizes generated and reduce drift . Spray nozzle height above the ground or on top of the crop canopy is significant factor that influence the risk of drift, specifically when there is need to apply fine/medium spray qualities. The minimum possible nozzle height remains an important part of any drift control strategy. Spray drift from nozzle is a function of the nozzle height and the wind speed at the time of spraying. The use of flat fan angle 110[degrees] at heights of more than 50 cm increases the risk of drift . Hobson et al  reported from computer simulation studies that nozzle heights of less than 50cm can be used with 110[degrees] nozzle angle and gives a better option for spray drift control than using nozzle has a narrower 80[degrees] spray angle and nozzle heights of 50 cm or more. Krishnan et al  used extended range fan nozzles of 110[degrees] above a patternator and found that wind velocity affected on spray pattern displacement. Sehsah et al  reported that the spray drift increased with increasing of the wind speed. The objective of this study is to examine the effect of spray nozzle angle and height on spray distribution and drift.
MATERIALS AND METHODS
The nozzles selected for the study are standard flat-fan nozzles TP6503, TP8003, and TP11003. These nozzles are manufactured by Spraying Systems, Inc. (Wheaton, Ill.) for broadcasting application and classified according to International Organization for Standardization (ISO) of size 03(0.3gpm).Static tests for discharge rate were conducted for nozzles by collecting amount of water directly from nozzle on a graduated container at pressure 300 kPa for one minute and measuring nozzle output with precision electric balance. The spray liquid was tap water. Water discharged from the nozzle was supplied from a 140 L pressurized bottle, the pressure was provided by a compressor and the pressure was adjusted by a pressure regulator. Tests were repeated three times and a maximal deviation of all nozzles with nominal flow rate was [+ or -] 2.5%.
Spray volumetric distribution and the effective spray pattern width for nozzles were determined in the laboratory by using a spray pattern analyzing system or patternator. The system was fabricate in workshop of University Technology Malaysia (UTM) and contains a 300 cm length x 100 cm width spray table with fifty V-shaped gutters (with 6 cm width x3 cm depth). During the tests, the spray table was inclined 6[degrees] from the horizontal plane. Static single nozzle was mounted on heights 50, 75 and 90 cm in the center of the spray table and at pressure 300 kPa. In front of the table, fifty tubes (250 mL) were used to collect the liquid from each channel. The weighting method was used to determine the transversal volumetric distributions collected during one minute by using a precision electric balance. Results of spray volumetric distribution were presented as (ml/min). After the spray pattern width was determined, wind tunnel was used to produce the cross wind speeds of 1, 2 and 3m/s to determine the total spray driftas shown in Figure 1.
The total spray drift from spray nozzle above patternator was calculated from the following equation 
D = 100[1 - [i=N summation over (i=1)][V.sub.i]/[Q.sub.o]] (1)
Where D represents drift percentage (%), i represent the test tube index; N the total number of test tubes, Vi the water quantity collected in the test-tube (ml/min) and [Q.sub.o] the nozzle flow rate. This test repeated three times. Measurements were carried out at an average temperature 31C[degrees] and an average relative humidity RH 79%. The calculations made use of the statistical package in Microsoft Excel. The data from spray tests were collected and analysis of variance (ANOVA) on spray drift was carried out, using a mathematical model for a completely randomized design. The F test was used to evaluate the significance of factors nozzle type, height and wind speed in the model, their interactions at the significance level 0.05 confidence intervals were determined to be 95.0% using SPSS software version 20.
RESULTS AND DISCUSSION
The spray volumetric distribution sometime is unimodal that is triangular shaped. In general; the nozzles gave spray distribution with a peak just below the nozzle centre and less spray towards the edges of the spray swath. Figure 2 shows that the use of the nozzles having spray fan angles of less than 110[degrees] will increase the spray peak under the nozzle center. The nozzle angle 65[degrees] gave the highest peak with volume 185 ml at height 50cm and just below the nozzle centre.
According to the results of analysis of variance table 1,the nozzle angle, height and wind speed and their interactions affected significantly on the spray drift.
Results of the wind tunnel experiments showed that the use of nozzles with smaller spray fan angles reduced the spray drift as result to increase droplet sizes as shown in Figure 3. The similar results were observed by Spraying System CO 
The volume of the spray liquid collected on the patternator increased markedly with reducing of the nozzle height as expected. The average of the lowest value of spray drift 9.009% was found at nozzle height 50cm as shown in Figure 4.The droplets fall down quickly when the nozzle height is low. These results were observed by Miller et al., .
Figure 5 shows that the wind speed significantly affected the spray drift in which the wind speed 3 m/s in comparison to the 1 and 2 m/s increased 448.8% and 70.7% in spray drift respectively. The droplets have no chance to move away the target when the cross wind speed is weak. These results were observed by Sehsah et al., .
The interaction of nozzle angle 65[degrees] and nozzle height 75cm in comparison to the interaction nozzle angle 110[degrees] and nozzle height 50cm achieved 21.65% less spray drift as shown in Figure 6. These results were observed by Miller et al., .
Figure 7 shows the combination of nozzle angle 65[degrees] and wind speed 3m/s in comparison to the combination of nozzle angle 110[degrees] and wind speed 2m/s achieved 24.65% less spray drift.
According to the Figure 8, the combination of nozzle height 50cm and wind speed 3m/s in comparison to the combination nozzle height 90cm and wind speed 2m/s achieved 32.79% less spray drift.
It is clear that interaction of the nozzle angle 65[degrees] and nozzle height 50cm and wind speed 1m/s achieved the lowest spray drift 2.20% in comparison to the all combinations as shown in Figure 9.
Very few of practical detailed studies had examined and focused on the factors affect spray distribution and drift. In this study, nozzle angle and height were proposed as tool to reduce spray drift. The results of this paper provide experimental basis to set up a simulation platform to evaluate total spray drift. The adopted protocol provides consistent values of the deposits on a patternator. It was noticed that spraying conditions significantly affected spray drift. Results of this paper showed that the risk of drift can be reducing by using of nozzles having spray fan angles of less than 110[degrees] at heights of greater than 50cm. However, the use of the minimum possible nozzle height remains an important part to control spray drift.
Received 23 December 2013
Received in revised form 25 February 2014
Accepted 26 February 2014
Available online 25 March 2014
This work was carried out in the wind tunnel of UTM and we gratefully acknowledge the support and assistance and advice from all members of the aeronautics laboratory.
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Nasir S. Hassen, Jamaludin M. Sheriff, Nor Azwadi C. Sidik
Department of Thermofluid, Faculty of Mechanical Engineering, University Technology Malaysia, UTM Johor Bahru,
Corresponding Author: Nasir S. Hassen, Department of Thermofluid, Faculty of Mechanical Engineering, University Technology Malaysia, UTM Johor Bahru, Malaysia. E-mail: email@example.com.
Table 1: Variance analysis of the effect of nozzle angle, height and wind speed on spray drift. source Type III Sum df Mean Square of Squares Intercept 21215.541 1 21215.541 angle 2485.860 2 1242.930 height 2416.099 2 1208.050 wind 6809.827 2 3404.913 angle * height 191.738 4 47.934 angle * wind 656.445 4 164.111 height * wind 885.243 4 221.311 angle * height * wind 39.207 8 4.901 Error 1.513 54 .028 Total 34701.473 81 Corrected Total 13485.932 80 Corrected Model 13484.419 (a) 26 518.632 source F Sig. Partial Eta Squared Intercept 757330.576 .000 1.000 angle 44368.846 .000 .999 height 43123.713 .000 .999 wind 121545.100 .000 1.000 angle * height 1711.113 .000 .992 angle * wind 5858.275 .000 .998 height * wind 7900.123 .000 .998 angle * height * wind 174.946 .000 .963 Error Total Corrected Total Corrected Model 18513.574 .000 1.000 R Squared = 1.000 (Adjusted R Squared = 1.000) (a) Fig. 3: Effect of the nozzle angles 65[degrees],80[degrees] and 110[degrees] on spray drift. Norzle angle ([degrees]) 65[degrees] 9.750 80[degrees] 15.529 110[degrees] 23.273 Note: Table made from bar graph. Fig. 4 : Effect of the nozzle heights 50, 75 and 90cm on spray drift. Nozzle height (cm) 50cm 9.009 75cm 17.296 90cm 22.247 Note: Table made from bar graph. Fig. 5: Effect of the wind speeds 1, 2 and 3m/s on spray drift. Wind speed(m/s) 1m/s 5.004 2m/s 16.034 4m/s 27.463 Note: Table made from bar graph. Fig. 6 : Effect the interaction between the nozzle angles 65[degrees], 80[degrees] and 110[degrees]and nozzle heights 50, 75 and 90cm on spray drift. 65[degrees] 50cm 4.652 75cm 10.700 90cm 13.899 80[degrees] 50cm 8.717 75cm 16.943 90cm 20.927 110[degrees] 50cm 13.657 75cm 24.246 90cm 31.915 Note: Table made from bar graph. Fig. 7: Effect the interaction between nozzle angle 65[degrees], 80[degrees] and 110[degrees] and wind speeds 1, 2 and 3m/s on spray drift. 65[degrees] 1m/s 2.384 2m/s 9.461 3m/s 17.406 80[degrees] 1m/s 5.157 2m/s 15.689 3m/s 25.741 110[degrees] 1m/s 7.472 2m/s 23.102 3m/s 39.243 Note: Table made from bar graph. Fig. 8: Effect the interaction between nozzle heights 50,75 and 90 cm and wind speeds1,2 and 3m/s on spray drift. 50cm 1m/s 3.344 2m/s 8.231 3m/s 15.450 75cm 1m/s 5.621 2m/s 17.033 3m/s 29.234 90cm 1m/s 6.048 2m/s 22.988 3m/s 37.706 Note: Table made from bar graph. Fig. 9: Effect the interaction between the nozzle angles 65[degrees], 80[degrees] and 110[degrees] and nozzle heights 50,75 and 90 cm and wind speeds1, 2 and 3m/s on spray drift. 65[degrees] 50cm 75cm 90cm 1m/s 2.203 2.350 2.500 2m/s 4.583 10.327 13.473 3m/s 7.170 19.423 25.623 80[degrees] 50cm 75cm 90cm 1m/s 3.667 5.570 6.233 2m/s 8.087 17.410 21.570 3m/s 14.397 27.850 34.977 110[degrees] 50cm 75cm 90cm 1m/s 4.163 8.943 9.310 2m/s 12.023 23.363 33.920 3m/s 24.783 40.430 52.517 Note: Table made from bar graph.
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|Author:||Hassen, Nasir S.; Sheriff, Jamaludin M.; Sidik, Nor Azwadi C.|
|Publication:||Advances in Environmental Biology|
|Date:||Mar 1, 2014|
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