The numerical modelling of the ejector pump working process with variable geometry of the flow channel

Abstract

The range of application of the ejector pumps for industry is extensive. The ejector pumps are used for gas, liquid and the multicomponent or multiphase mixtures transport. The stream-flow devices (pumps, compressors) has several advantages, for example: simple design, schema without moving parts, high reliability. Possibility of working with multiphase mixtures for ejectors determines their usage in the oil and gas mining systems as part of pumping stations for oil and gas pipe transport. Hydrodynamic of the stream-flow devices, which are used for oil and gas pipe transport, was researched good over a span of last years. This allows create optimal design of flow channel for ejectors. However, in the real life, in the working process of pumping station, is the flow unstable with the random occurrence of the gas and liquid slugs. Известно, что при перекачке газов длина камеры смешения должна быть значительно больше, чем при перекачке жидкости. In this way, creating design of ejectors for both effective gas and oil transport is very difficult problem. It is known that a length of the ejectors mixing section should be longer by gas transport than by liquid transport. In this paper was presented variant of the ejector’s flow channel with variable geometry, which was designed as the moving conical body in diffuser section. In this configuration, the annular conical channel between conical body and inner surface of diffuser is propagation of the mixing section and allows to effective mixing of components in ejectors with the short cylindrical mixing section actually. The diffuser’s function - converting kinetic energy of flow to pressure energy - holds because the surface area of annular channel increases in flow direction. The move of conical body in diffuser allows to control of the fluid transport efficiency. Researches are made as numerical flow simulation with CFD STAR-CCM+. This gives the possibility to the detail research all mixing processes with the analysis of the velocity, pressure and volume of fraction fields and flow.