1. Wind tunnel protocol for spray drift assessment Ch. Stainier, F. Lebeau, Destain M.-F., Schiffers B.

2. Introduction The objective of wind tunnel protocol is to measure spray drift in a reproducible way in order to evaluate the relative drift potential of: –different spray nozzles –different operating parameters (Pressure, Height,…) –different formulation and adjuvants

3. Introduction A normalisation process is underway at the international level: ISO/DIS 22856/1 within TC23/SC6. It defines: –Typical wind tunnel design and layout (2*2m section, measurement section) –Examples of measurement methods –Wind turbulence and heterogeneity thresholds –Wind tunnel instrumentation (humidity, wind speed, temperature) –Typical test reports

4. Introduction Some major hurdles remain as the ISO/DIS 22856/1 protocol is designed for a static nozzle: –The long axis of flat fan nozzle is set perpendicular to air flow, what is not representative of field drift condition –The blockage effect of droplet induced air-flow generate vortexes entraining driftable droplets resulting in a very specific pattern –The collectors are prone to saturation due to local overdoses

5. Introduction The presentation intend to present the protocol developed in Gembloux which is based on traversing –an ISO/DIS 22856/1 wind tunnel –a moving nozzle with controllable speed –fibre glass ground samples

6. Closed loop allows the use real formulations Speed up to 6 m/s Droplet filter Low turbidity Moving boom Large test section The wind tunnel facility

7. The wind tunnel controllable parameters Wind speed 0 - 6 m/s (more with reduced wind homogeneity) Temperature (cooler and heater) Relative Humidity (water atomisation)

8. 0.8m 6m Spray nozzle orientation Wind direction (2m/s) Nozzle displacement axis (2m/s) WIND TUNNEL TEST SECTION Ground collector Standard settings : Wind speed = 2m/s RH = 80%T° = 20°C P = 3 barH=50cm Glass fibre collectorsNozzle speed = 2m/s The Gembloux measurement protocol (aerial view)

9. parametersMeanCV (%) Wind (m/s)2.0260.814 Temp (°C)19.6840.137 RH (%)79.7970.100 P (bar)3.0930.393 FF 110 02 (LU) Results repeatability

10. parametersmeanCV (%) Wind (m/s)1.8251.162 Temp (°C)19.2070.185 RH (%)78.8580.177 P (bar)2.8920.281 DG 110 04 Results repeatability

11. parametersmeanCV (%) Wind (m/s)2.0061.048 Temp (°C)19.2870.125 RH (%)68.9580.132 P (bar)3.0290.194 XR 110 04 Results repeatability

12. FF 110 02 (LU) Results wind speed

13. DG 110 04 Results wind speed

15. Conclusion Repeatability is very satisfactory Small differences can be highlighted Other drift measurement methods can be used A Gaussian tilting plume model is developed in order to predict drift of a moving nozzle