Aerial spraying operation of agricultural is an important pest and disease chemical control technology, and plays an important role in agricultural production. Compared to artificial, tractors and other methods, the method of agricultural fixed-wing aircraft spraying has the advantages of high efficiency, strong assault, low cost, and crops friendly etc. The drift of spraying droplets in the operation of fixed-wing aircraft would pollute the environment and even harmful for human health. Therefore, it was noticed by public and regulators. On the other hand, how to avoid re-spraying, leak spraying in the spraying operation of fixed-wing aircraft and improve the efficiency of spraying is also a concern of users. The drift of the fixed-wing aircraft spraying droplets drifting is impacted by multi factors, e.g. the aircraft wake vortex movement, the environment wind field, droplet size, crop canopy etc., and with greater Uncertainty. Thus, it is necessary to study the wake vortex wind field during the operation of fixed-wing aircraft, and the study result would provide a theoretical guidance for aerial spraying operation.

In this study, based on the GILL three-dimensional ultrasonic wind speed sensor, a set of measurement system of wake vortex wind field of fixed-wing aircraft which includes four parts: wind speed sensor, data acquisition module, industrial computer and data analysis software, was established. According to the results of computational fluid dynamics (CFD) calculations, the wake vortex motion was analyzed and based on this point, a vertical and horizontal brackets were designed to fix the wind speed sensor. The brackets capture the wake vortex motion from the normal and the spanwise directions respectively. The vertical bracket used in the study is 4.5 m high and 9 wind speed sensors were arranged with interval of 0.5m, the horizontal bracket with a length of 16 m, middle interval of 2 m, the most lateral interval of 4 m, and 7 wind speed sensors were arranged. Besides, two wind speed sensors were arranged in the vertical direction with interval of 2 m. The remaining wind speed sensor, as a reference point, was arranged outside the influence area of the trailing vortex, which was used to collect the background information of the atmospheric environment.

In September 26, 2015, the tail vortex wind field measurement experiment was carried out in Jiamusi, Heilongjiang and the Beidahuang General Aviation Company. The experimental aircraft is Thrush 510G, and the flight height is 5m, the flight speed is 200 km/h (55m/s). In the experiment, the vertical bracket was placed at positions of 15m, 20m and 30m on both sides of the flight path for a total of 12 experiments respectively, and the horizontal bracket was placed at positions of 10m, 20m and 30m on both sides of the flight path for a total of 24 experiments. The vertical and horizontal vortex induced velocity distributions and their regularity with time were measured in the experimental. The wind field model of aircraft wake vortex was established by using the experimental data, which lays a foundation for further research on the drift motion law of droplets in wind field.