Low-Drag Supercavitating Axisymmetric Bodies

摘要

A numerical procedure which is free from the usual linearizing assumptions was developed for the generation of low cavity drag, supercavitating axisymmetric bodies with infinite trailing cavities (zero base cavitation number). The method consists of exact streamline plotting from an axial sink-source distribution which is selected to give the best approximation to a cavity flow past an axisymmetric body. The fore-body is designed to withstand small negative pressure since in actual operation, the vapor cavitation number of the flow is always greater than zero. Two families of bodies were generated. For the same fineness ratio, one family gives a slightly larger volume and slightly lower minimum pressure coefficient, or lower cavitation inception speed than the other. Both families of bodies have cavity drag coefficients (normalized with respect to the base area) about one order of magnitude smaller than the friction drag coefficients. The cavity drag coefficients of the derived bodies are also about one order of magnitude less than the cavity drag coefficients of paraboloids of the same fineness ratio. (Author)