Исследование и расчет гидродинамики в струйном насосе

Abstract

Survey of researches of the jet pump are executed. It is presented that its calculation are based, as a rule, on the quasi-one-dimensional models which are founded on equations of flow-rate, energy, quantity of motion balance. One-dimensional theories interrelate of streams parameters on an entry and an exit of the apparatus and its than components. Definition of parameters distribution along ejector pump are not obviously possible. It is hindered because, on the one hand, more full understanding of working process, on the other – an optimum roll forming of the apparatus setting. The method of CFD allowed to analyse the pump working process in details. This is proved by publications deals with research the setting shape influence to power and cavitation characteristics of the pump. This paper purpose is deriving numerical model of fluid flow in the jet pump setting, definition of speed and pressure fields in the area of passive medium implicating in cocurrent moving with a stream. The materials of laboratory tests of the jet pump and a numerical model of a fluid flow are presented. The model based on equations: continuity; Navier-Stokes; transport equations of a turbulence kinetic energy k and relative dissipation speed ε of this energy. The numerical model are solved in ANSYS Fluent software package. Laboratory tests of the jet pump is conducted at the stand in laboratory of the department “Hydraulics and hydropneumatic systems” of South Ural State University. The jet pump is fulfilled with the conic nozzle, the open suction chamber, the straight-diffuser mixing chamber, the diffuser. The active and common fluid flow volume charges; static pressures before a nozzle, on an entry of the mixing chamber and in the exit from the pump; fluid temperature are measured in experiments. Results of laboratory and numerical researches are compared. Validity of the presented numerical model of a fluid flow in the jet pump setting is proved. Fields of speed and pressure in suction and mixing chambers of the pump are calculated for several back pressures. It is proved that the latter influence not only on distribution of speed and pressure in the plenum chamber, but also in a suction chamber on a section from a nozzle exit section to input cross-section of the mixing chamber. Thus the greatest irregularity in the pressure distribution is observed in a nozzle exit section plane, and the greatest irregularity in the speed distribution is observed in input cross-section of the mixing chamber. The jet flow of an active flow in an suction chamber is not isobaric. The greatest local pressure undershooting is observed at the nozzle edges when minimum pressure is equal to pressure value of saturated steams that led to generation of steam and the cavitation phenomena in the jet pump.