Thermal Choking and Condensation in Nozzles

An experimental and analytic analysis of water‐vapor condensation zones in moist‐air expansions is considered where the heat addition of condensation exceeds that for thermal choking. The transition from an unchoked to a choked flow is shown experimentally and described from the viewpoint of an analogous isentropic nozzle. Solution of the one‐dimensional equations of motion for a fully choked nozzle flow involving shock waves is given, and sonic point locations are verified experimentally. Special emphasis is given to the effect of heat addition and area variation on flow behavior in the region of sonic points. It is concluded that the onset of condensation in experiments involving shock waves can be used in testing theories of homogeneous nucleation.