Development of a New Potential Flow Based Model for Hover Performance Prediction

This paper presents recent developments in hover performance prediction using the potential-based wake method, known as ivorticity embedding.i The method uses a Computational Fluid Dynamics (CFD) solution of the potential equation and captures the vortex-induced velocities as part of the total o w eld. The method uses an auxiliary vortical velocity eld that describes the wake structure and acts as a forcing function to the potential equation. This eld is, in turn, constructed from circulation-carrying wake markers, whose location is determined by a Lagrangian convection. Various aspects of the solution process, and their effects on convergence, are discussed in-depth. Two modes of operation of the method are discussed. The rst of these is a istand-alonei mode, useful for preliminary design, in which the rotor is described as a ilifting surface.i The other, intended for detailed analysis, is a hybrid mode that couples a vorticity-embedding solution for the wake with a conventional Reynolds-Averaged Navier-Stokes (RANS) solver for the blade. These methods are demonstrated by comparison with UH-60A performance, wake and loads data.