吸入压力对水蒸汽喷射泵抽气性能影响的数值分析

Simulation of Steam-Jet Pump Operating at Different Suction Pressures

为研究水蒸汽喷射泵内部工作蒸汽与被抽气体的流动及其相互作用规律,考察被抽气体压力改变引起的膨胀比、压缩比变化对泵性能的影响机制,基于realizablek-ε湍流模型,建立了描述喷射泵内跨音速流动的数学模型。对喷射泵内压力沿壁面的分布进行了数值模拟。模拟结果与实验数据有很好的一致性,验证了理论模型的适用性。应用所建模型,在不同被抽气体压力条件下,对喷射泵内部被抽气体流动迹线、质量流率分布进行了数值预测,并计算了泵的引射系数。结果表明,被抽气体的质量流率随吸入压力的升高而增大,在被抽气体有效流动截面变化不大的情况下,使喷射泵引射系数相应增加,说明被抽气体压力增加引起的压缩比减少对引射系数的增加作用强于膨胀比减小对引射系数的减小作用。

The transonic flow of the steam-jet pump operating at different suction pressures was modeled by modifying the realizable k-ε turbulence model,and simulated with commercial computational fluid dynamics（CFD） code FLUENT 6.2.The impacts of the pressure ratio and its variations originated from changes in the pumped gases pressure on the characteristics of the pump,as well as the flow behavior of the primary and secondary fluids in the steam ejector were calculated.Moreover,the pressure distributions on the mixing chamber walls were simulated.The secondary fluid path-lines and mass flux profiles at different suction pressures were predicted.The simulated results show that the pressure ratio significantly affects the pumping,and that an increase of suction pressure results in a higher mass flow of the gases to be pumped,accompanied with higher entrainment ratio.The simulated results were found to agree fairly well with those of the measurement.