Comparison of Kinetic Energies of Different Spraying Systems

Rainfall simulators have been used for research of soil erosion by water for many years. Scientific teams around the world own a variety of different devices. In the case of comparing the results of several teams, the problem is the rainfall characteristics of different devices and therefore different input parameters. In this contribution, 3 devices were compared: a small rainfall simulator of the CTU, a small rainfall simulator of Tubingen University, and a laboratory rainfall simulator of the CTU. A laser diffractometer (Thies Clima Laser Precipitation Monitor 5.4110) was used to determine the kinetic energy (KE) and rainfall intensity and splash cups filled with sand (Tubingen Splash Cups, designed by Scholten et al., 2011) were used to compare the methods of the kinetic energy measurement. On each device, measurements were made on a plot with area 1 x 1 metre at nine positions with a rainfall intensity set at 60 mm h^-1.

Significant differences among the devices were observed using the laser disdrometer. Small rainfall simulator of Tubingen University achieving a KE of approximately 2.5 J m^-2 mm^-1, small simulator of the CTU a KE of approximately 5.5 J m^-2 mm^-1, and the laboratory simulator of the CTU a KE of approximately 8 J m^-2 mm^-1. The kinetic energies obtained by the splash cups did not reach the values produced by the laser diffractometer. During the experiments, local irregularities in rainfall were observed associated with different types of nozzles and different simulator constructions. The splash cups (46 mm in size) allowed one to measure exact locations proving that locally KE can reach much higher values.

The experiments proved that the differences among different simulator constructions can greatly affect the results of the experiments performed, and the method of assessing the rainfall characteristics can help to understand the real functioning of each device.

This research was supported by the research projects QK22010261, Mobility 8J23DE006, and by the Grant Agency of the CTU in Prague SGS23/155/OHK1/3T/11.