A Proposed Calibration Procedure for the Simulation of Wind-Driven Rain in Small-Scale Wind Tunnel

Abstract

The simulation of wind-driven rain in the wind tunnel should ensure a realistic representation of rainfall events in a laboratory environment. It necessitates therefore an understanding of how the governing input parameters of the tunnel relate to its outputs. In this perspective, a preliminary calibration should be carried out in order to grant the reproduction of a homogeneous volume of rainwater and a natural raindrop size distribution. A precise and straightforward procedure to be followed is missing. Based on experimental investigations, this study outlines a series of calibration steps that should be performed in the wind tunnel before the rain simulation takes place. It applies in particular to small scale facilities as opposed to the large wind tunnels designed for full-scale testing of building components and vehicles. Such procedure concentrates on the following aspects: wind speed calibration by vane anemometer; calibration of the sprinkler system and rain intensity measurements for assessing its spatial distribution. The main findings include the introduction of a governing function for the sprinkler system, a method for rain mapping as well as the individuation of an optimal set-up in the wind tunnel for rain simulation.