General Reynolds Analogy for Blunt-Nosed Bodies in Hypersonic Flows

The relation between skin friction and heat transfer for blunt-nosed bodies in hypersonic flows, named the general Reynolds analogy, has been investigated by using the theoretical modeling and the DSMC methods. First, based on the boundary-layer flow properties, the ratio of the skin friction to the heat transfer for the blunt-nosed body was found proportional to the local surface slope angle. As a typical demonstration, an explicit expression of the ratio was derived for circular cylinders. Also, numerical calculations indicated that this characteristic exists for other blunt-nosed shapes, even in chemically reactive flows. Second, the analogy in rarefied gas flows was analyzed. In the rarefied flow regime, the deviation from the linear distribution of the ratio was proved to be controlled by the rarefied flow criterion. This study, combined with former investigation on the flat plate leading-edge flows, clarifies the general Reynolds analogy in the whole flowregime for both flat plates and blunt-nosed bodies in hypersonic flows.