Extension of Multipole Analysis to Laterally Asymmetric Flowfield Around Supersonic Flight Vehicle

摘要

This Paper introduces an extension of so-called multipole analysis, which reduces the computational cost associated with predicting a supersonic vehicle's sonic boom signature on the ground. Multipole analysis enables the modification of the near-field waveform of a supersonic flight vehicle to account for the effect of coalescence in the circumferential direction, even in the same position as the extracted waveform, which results in a large reduction of the computational region of the computational fluid dynamics analysis in the vehicle's vicinity. However, multipole analysis cannot consider a flowfield with lateral asymmetry, which often occurs when dealing with practical vehicle configurations or real flight conditions. The authors have implemented a multipole analysis tool named MPnoise and extended the tool to laterally asymmetric flowfields. It is shown in this Paper that such an extension is easily accomplished by introducing sinusoidal terms into the original, laterally symmetric formulation of multipole analysis. Also shown is a successful convergence between waveforms computed with and without multipole analysis, even when the flowfield has a slight asymmetry in the lateral direction.