TRACKING OF RAINDROPS IN FLOW OVER AN AIRFOIL

The splashback that occurs when raindrops impact an airfoil results in an ''ejecta fog'' of small droplets near the leading edge. Accelerati on of these droplets by the air flowfield is a momentum sink for the a irflow and has been hypothesized to contribute to the degradation of a irfoil performance in heavy rain. Presented here is a one-way coupled Lagrangian particle tracking scheme to evaluate droplet concentrations and the associated momentum sink around a NACA 64-210 airfoil section for three rainfall rates. A laminar air flowfield is determined with a standard CFD code and is used as input to the particle tracking algo rithm. Raindrops are assumed to be noninteracting, nondeforming, nonev aporating, and nonspinning spheres, and are tracked through the same c urvilinear grid used by the airflow code. A simple model is used to si mulate impacts and the resulting splashback on the airfoil surface.