Thermal choking in two-dimensional expansion flows

Two-dimensional supersonic flows with heat addition from given internal sources and/or nonequilibrium condensation are considered. The critical amount of heat necessary to thermally choke the flow is defined at any point in the flow field, and the necessary and sufficient conditions for thermal choking are identified from the singularities of the equations of motion along streamlines. In particular, for any practical purposes, it is shown that the flow Mach number reaches unity at any point where the heat added to the flow along the streamline passing through that point reaches the critical value. Thermally choked flows are then identified as those flows where the critical heat along streamlines is exceeded leading to embedded oblique shock waves with a local subsonic Row field downstream.