Phenomenological and mathematical modeling of a high-pressure steam driven jet injector

An injector is a particular type of jet pump which uses condensable vapor to entrain a liquid and discharge against a pressure higher than either motive or suction pressures. The injector has no moving parts and requires no external power supply nor any complex control system. Thus, the injector is particularly suited for emergency core cooling operations.; A detailed survey has indicated that various injector designs are available for operating pressures below 250 psig. However, the design of these injectors from the viewpoint of a basic understanding of heat and mass transfer processes has not been well developed. A critical review of the models showed serious discrepancies between the analytical models and the experimental observations. The discrepancies evolved from the neglect of non-equilibrium aspects of the flow. The origin of the non-equilibrium aspects can be traced to the extremely small time scales governing the flow in the injector. Thus, time scales of the order of 10{dollar}sp{lcub}-2{rcub}{dollar} seconds are involved in the injector, accompanied by mass, momentum, and heat transfer rates of orders of magnitude higher than that observed in conventional two-phase flows.; Thus, the present study focuses on the phenomenological and mathematical modeling of the processes in the injector from the viewpoint of its non-equilibrium nature. Thus, the expansion of steam in the supersonic nozzle is modeled on the basis of compressible gasdynamic equations with allowance for non-equilibrium homogeneous condensation and condensation shocks. The condensation of the supersonic steam on to the injected water is modeled by steam side limited condensation onto an atomizing liquid jet. The conversion of the momentum into pressure as a consequence of condensation shocks, is modeled using non-equilibrium bubble collapse theories. The proposed models are supported by the literature drawn from diverse fields and applications like turbine designs, quantum physics, cloud formation studies, atomizers, fuel injectors, nuclear applications, rocket and marine propulsion studies, and from the vast literature on cavitation.