基于CFD数值模拟下的蒸汽喷射器性能预测

建立了蒸汽喷射器热力学模型，并验证了该模型性能及结构计算的可靠性。并针对实际情况中，对该模型进行了动态模拟。结果显示：当工作流体的温度升高时，工质流体的质量流量都会增加，引射系数存在峰值，峰值所对应温度为热力学模型设定温度值；当引射流体的温度升高时，其质量流量也会随之增大，而工作流体的质量流量则较稳定，因此引射流体温度与压力的升高可以改善喷射器的性能；当背压升高时，在一定压力范围内，工质流体的质量流量都趋于稳定，而当背压超过热力学模型设定背压值时，引射流体的质量流量便随背压的升高而急剧下降，喷射器性能严重恶化，故认为该压力值为喷射器的临界背压。本文研究结果对喷射器的设计计算具有一定的指导作用。 关键词：蒸汽喷射器；热力学模型；数值模拟；引射系数

Performance prediction of steam ejector based on CFD numerical simulation

A thermodynamic model of the steam ejector was established, and the performance and the reliability of the structural calculation of the thermodynamic model were verified. For practical purposes, the model was dynamically simulated. The results show that when the temperature of the primary fluid rises, the mass flow of the working fluid will increase, there will be a peak value of the ejecting coefficient, and the temperature corresponding to the peak is the temperature utilized for construct the thermodynamic model; When the temperature of the secondary fluid rises, its mass flow rate also increases, while the mass flow rate of the primary fluid is relatively stable. Therefore, the increase in the temperature and pressure of the secondary fluid can improve the performance of the ejector; When the back pressure increases, the mass flow rate of the working fluid tends to be stable within a certain pressure range, and when the back pressure exceeds the back pressure value utilized for construct the thermodynamic model, the mass flow rate of the secondary fluid decrease sharply with the back pressure rises, and the performance of the ejector is severely deteriorated. Therefore, the setting back pressure is considered to be the critical back pressure of the ejector. In conclusion, the research results in this article have certain guiding effect on the design and calculation of the injector.