Periodic Nozzle Flow with Heat Addition

Abstract
Experiments on cyclic, unsteady compressible flow with heat addition are reported. Frequencies of oscillation of pressure, density, etc. of up to 6,000 Hz are noted in the transonic region of Laval nozzles. The unstable flow is caused by heat addition due to condensation of water vapor in air. A dimensional analysis is given where the essential variables are identified without recourse to an understanding of the details of the condensation process. A stability diagram is presented and the process is explained in qualitative terms