SUPERSONIC COOLING BY SHOCK VORTEX INTERACTION

The subject of total temperature separation in jets was treated in Fox et al. (1993) for subsonic jets. When we extended this study to the c ase of supersonic jets, we found the presence of a different mechanism of cooling, an effect which does not appear to have been known in the past. Named the 'shock-induced total temperature separation', this co oling can be of much greater magnitude than the subsonic cooling treat ed previously; it is caused by the interaction of convected vortical s tructures near the jet exhaust with the shock structure of the superso nic jet. In studying this phenomenon, we focus our attention on overex panded jets exiting a convergent-divergent nozzle. The theoretical res ults for the shock-induced cooling which are based on a linearized, un steady supersonic analysis are shown to agree favourably with experime nts. When an impingement plate is inserted, the shock-induced cooling would manifest itself as wall cooling, whose magnitude is significantl y larger than the subsonic counterpart. This has implications for heat transfer not only in jets, but wherever vortical structures may inter act with shock waves.