Self-excited oscillation of non-equilibrium condensation in critical flow nozzle

The unsteady flow with vapor condensation in critical flow nozzle includes many different self-excited periodic oscillation modes and might affect its flow field and mass flow-rate. The instability of condensation in transonic nozzle flow was discussed firstly. To investigate the phenomenon of self-excited oscillation and bifurcation induced by non-equilibrium condensation of the pure superheated steam flow in critical flow nozzle, an Eulerian viscous flow solver using SST k-ω turbulent model for vapor condensation was established and validated by experimental data of both steady and unsteady condensations, and algebraic formula. Three self-excited symmetric oscillation modes were classified by the oscillation amplitude and frequency of induced shock. The phenomenon of symmetric oscillation modes and asymmetric bifurcation were discussed in detail. Moreover, the effect of self-excited oscillation on its mass flow-rate was clarified. The maximum deviation of mass flow-rate is 1.2%, which is worthy of attention.