An approach to rainfall simulator automation and performance evaluation

A computer-PLC (Programmable Logic Controller) control solution was proposed for the artificial trough rainfall simulator. The rainfall process with continuous changing intensities was simulated automatically with the control strategy. Frequency-tunable pulse signal of specified duty ratio was generated precisely using pulse module of PLC to drive nozzles oscillating at required frequency. Thus, arbitrary rainfall intensities within the output range of the simulator were achieved. Control configuration for trough rainfall simulator was built using Forcecontrol man-machine software. Parameters settings and rainfall intensities tracking during the rainfall simulation were realized. Simultaneously, a rainfall simulator performance evaluation procedure was performed based on a single nozzle rainfall test with six selected working states. A criterion of dynamic rainfall uniformity was proposed to estimate the performance of a rainfall simulator during the entire rainfall simulation. A Locally weighted scatterplot smoothing (LOESS) and weighted averaging approach was adopted in the evaluation procedure.