激波结构对喷射器工作特性的影响

Influence of Shock Wave Structure on the Ejector’s Operating Characteristics

喷射制冷循环系统因其采用水作为工质不仅节能环保而且可以实现循环利用.本文采用数值仿真方法,对喷射制冷系统核心部件——喷射器内部的激波结构进行了讨论和详细划分.首次给出了伪激波区域、混合区域、激波串区域以及正激波位置的判定依据.讨论了激波结构对喷射器工作特性的影响.研究结果表明,正激波的位置受喷射器出口背压的影响;伪激波区域是决定喷射器引射效率的直接因素;激波串对降低喷射器内部流动速度和压力恢复起到重要作用.激波混合层的存在将工作蒸汽与引射蒸汽的流道分开.工作蒸汽通过激波混合层来携带和加速引射蒸汽的流动.激波混合层的面积大小受喷射器的几何结构和工作蒸汽的工作条件所影响.因此,了解和掌握激波结构对于理解喷射器内部流体流动规律,提高喷射器工作效率,进一步改进和优化喷射器的几何结构,具有参考价值.

An ejector refrigeration recycle system can not only save energy and protect the environment but also realize recycling because it uses water as the working medium.The structure of the shock wave inside the ejector,i.e.,the core component of the system,is discussed and divided in detail by numerical simulation.The determination basis of the pseudo‑shock region,constant velocity region,oblique shock region and positive shock region is given for the first time.The influence of shock wave structure on the ejector’s operating characteristics is discussed.The results indicate that the position of positive shock wave is affected by the outlet back pressure.The pseudo‑shock region is the direct factor that determines the ejector’s entrainment ratio.Shock train is important in reducing the flow velocity and restoring pressure in the ejector.The presence of a shock‑mixing layer separates the working steam from the flow path of the ejecting steam.The working steam passes through the shock‑mixing layer to carry and accelerate the flow of the ejecting steam.The area of the shock‑mixing layer is affected by the ejector’s geometry and the working conditions of the working steam.Therefore,understanding and mastering the structure of shock waves is of reference value to understand the internal fluid flow law of the ejector,to improve the working efficiency of the ejector,and to further improve and optimize the ejector’s geometry.