Body resistance in a detonating gas flow

Abstract

The purpose of the present study is to demonstrate that previous assumptions made concerning the effect of heat liberation on the aerodynamic characteristics of bodies are too broad, and that the estimates of resistance reduction obtained are elevated. Other cause must be sought to explain the facts observed in experiment: the influence of viscous and nonstationary effects, flow turbulization, change in bottom pressure, etc. The paper analyzes the effect of heat liberation on the value of braking pressure behind a detonation discontinuity. Equations are given that express the ratio of the braking pressure to the conventional shock wave pressure. The equation system was solved numerically by the nonstationary finite difference method. The solution shows that the decrease in wave resistance of a blunted body and profile due to heat liberation in the shock layer cannot reach values of 40-50% as observed in experiment, so that other mechanisms must be sought to explain this effect. In addition, calculations were also performed for flow of a detonating gas over segmental-conic bodies with blunt leading edges and planar bodies with various reverse wedge angles. It was established that heat liberation leads to an increase in the intensity of the tail discontinuity, although themore » rise in pressure on the back part of the body or profile is insignificant, so that the resistance coefficient of the body falls in these cases by not more than 2-8%.« less