Adaptive Grid Sequencing and Interpolation Schemes for Helicopter Rotor Wake Analyses

Abstract

Numerical acceleration schemes have been developed to improve the computational efficiency of free-vortex analyses of helicopter rotor wakes. Two general methodologies were formulated based on adaptive grid sequencing and velocity field interpolation schemes. Both approaches considerably reduce the number of induced velocity evaluations in free-vortex schemes but without significant loss in predictive accuracy of the wake geometry. The methods have been implemented and evaluated for a rotor wake analysis based on a pseudoimplicit predictor-corrector (PIPC) relaxation algorithm. The acceleration schemes were found to produce up to an order of magnitude decrease in execution times. Both methods are generic in formulation and application and may be adapted for use in other free-vortex methodologies. A third method that specifically exploits the pseudoimplicitness of the PIPC scheme has also been developed, resulting in further increases in computational efficiency