Numerical Analysis On Performance And Configuration Of Ejectors Two Dimensional Flows Filed

Ejector pump is a kind of equipment which makes mutual energy change of two kinds of fluids happen and commingles them into a mixed one. This machine is extensively used in various industries, however, the theory study and working-process research for the machine are slowly developed due to the complicated inside flow field of ejector and the deficient theory study of hydrodynamics. For a long time, the operation and design of ejector have followed the one-dimensional rule; nonetheless, the lagged one-dimensional rule could not provide enough theoretical support to optimize the operating condition and structural design since the configuration of ejector is three-dimensional and the physical phenomenon is special.This dissertation adopts the fluid analytical software-FLUENT to realize the numerical analysis on the two-dimensional flow field and working-process of steam ejector through the method of CFD numerical simulation. It shows the realization process of this kind of numerical simulation comprehensively and especially; this article expounds the essence of CFD method: the elements, the governing equation, the discretization, the area discretization, onflow equation, the result finding process of discretization equation and so on. After the further analysis of simulation result, the careful observation of flowing phenomenon and special status inside ejector, and the investigation of possible contributing factors to the inside flow field, the generation of surging wave and the ejection performance especially like the pressure of operating-steam, jet-steam and mixed-steam, it comes to the conclusion that boosting pressure of operating-steam could not always enhance the performance, sometimes, if the pressure is exorbitant, it will deteriorate the flow field and make even worse operation. Conforming to the operating-steam, the mixed-steam pressure also has important influence to the performance. The ejector can only work normally under a given pressure number, and if the pressure of mixed-steam exceeds the number, the ejecting coefficient would come down quickly. Except for working parameter, the configuration of ejector also plays a crucial part to capability. The existing design method is based on semi-empirical formula coming from one-dimensional constant entropy suppose. This formula can only forecast the overall performance, and it is helpless when comes to the idiographic part. In order to surpass this limitation, the paper, on one hand, displays the flow fields and parameter distribution by the method of result finding of two-dimensional flow fields; on the other hand, with the advantages of CFD (such as flexibility, repeatability and cost-saving), it shows the influence of configuration to ejector performance by adjusting the figuration and dimension of each part of ejector. The result of simulation proves that it is effective to enhance the working efficiency of ejector by optimizing the configuration of the machine.