Visibility Enhancement in Rotorwash Clouds

Abstract

Enhancing vision in rotorwash dust and snow clouds using remote sensing devices would improve the safety of helicopter operations. Our approach is to simulate remote sensor performance by modeling brownout cloud microphysical conditions. We use computational fluid dynamics techniques to model rotorwash, assuming incompressible and laminar flow, to develop the nearfield and farfield flow around a rotorcraft of given weight and configuration. We are developing two phase flow techniques to incorporate dust particles into the flowfield. Currently, stochastic techniques are being used to simulate particle entrainment in the boundary layer, with ongoing research to model entrainment using more realistic boundary conditions of turbulent flow impinging on a porous, erodible bed. Sensor signal performance is being simulated with MODTRAN, driven by the synthetically created cloud particle size distribution and concentration.