High-Resolution Simulation of Parallel Blade-Vortex Interactions

Abstract

The physics of a parallel blade―vortex interaction is studied numerically and the predicted pressure and acoustic results are compared with experimental measurements. A high-resolution solution of the compressible Euler equations is performed on structured overset meshes. Initially, a two-dimensional airfoil-vortex interaction is studied for both a case where the vortex misses the blade and a case of direct impact. The vortex is initiated in the flow as a perturbation to the freestream conditions and is free to evolve, thus allowing for the deformation of the vortex as it interacts with the blade to be studied. The simulation is seen to accurately reproduce the experimental results and the emission of the acoustic waves from the airfoil surface is observed in detail. Acoustic energy generated by the interaction is seen to primarily radiate from the leading-edge section of the airfoil with a weaker contribution coming from the trailing edge. The simulations are then extended to three-dimensional moving overset meshes where the vortex generation and convection is also resolved. The numerical methodology is seen to accurately preserve the vortex strength and accurately reproduce the experimentally measured blade surface pressures and acoustics. The computations presented here face similar challenges to that encountered in the simulation of realistic helicopter blade—vortex interaction, but the computational costs are such that the solutions can be well resolved, and comprehensively validated using moderate resources.