Calculation of static pressure field of liquid phase in the active zone of cavitation-jet deaerator

Abstract

In cavitation-jet deaerators, the process of desorption of dissolved gases proceeds when boiling overheated water is directed in the form of a swirling vortex flow into the rarefaction zone. The removal of gases is carried out from the cavitation pocket formed along the flow axis. Such deaerators are characterized by relatively low efficiency. However, their small dimensions and the ability to work without supplying a heating coolant make them useful in cases where effective deaerators of other types cannot be applied by weight and size characteristics or temperature conditions. The expansion of the scope of practical application of cavitation-jet deaerators is hampered by the lack of appropriate mathematical description that would allow solving the problems of their schematic and constructive improvement. One of the main tasks in this case is to calculate the static pressure field of the liquid phase in the deaerator core. There are no ready-made solutions to this problem in the framework of previous studies. Thus, it is relevant from scientific and practical viewpoint to develop a simulation model of active zone of cavitation-jet deaerator, which allows determining the hydrodynamic characteristics of water flows and gas-vapor mixture when the elements, the mode of water supply and drainage evaporation change. Modeling the hydrodynamic situation in the active zone of cavitation-jet deaerator is based on the numerical solution for the Navier-Stokes equations and the continuity equation. These equations are written in the Reynolds decomposition. In this case, the standard k- turbulence model is used to obtain a preliminary solution, which is then refined during the transition to the SST turbulence model. The model is implemented by means of a software package for calculating fluid flows FlowVision. For the first time, a simulation model of the active zone of cavitation-jet deaerator was developed, which made it possible to determine the hydrodynamic characteristics of water flows and gas mixture when the elements design, the mode of water supply and drainage evaporation change. The field of static pressures of liquid phase in the active zone of cavitation-jet deaerator is determined. The results obtained do not contradict the published data describing the operation of cavitation-jet deaerators. In particular, they confirm an increase in the probability of deaerator overflow when gas exhaust is turned on. The results also prove the presence of a significant dependence of the deaeration efficiency on the hydraulic resistance of the evaporation suction tract. Based on the results obtained, a mathematical model of the deaeration process under the considered conditions can be developed.