Optimization Design Of Radial-axial Turbine

As the core component of the air cycle refrigeration system, radial-axial turbine has thecharacteristics of high single-stage expansion ratio, compact structure and high efficiency, so it iswidely used in aviation, vehicles and other fields. Gas flow in the impeller channel of radial-axialturbine is complicated, it is easy to produce secondary flow and air impact loss which can affect theperformance and the life of the turbine. In order to reduce the flow loss and improve the efficiency ofthe turbine, it is necessary to optimize the impeller.Numerical calculation and Kriging model method are used to simulate and analyze the process ofimpeller optimal design. The research work mainly include the following several parts:1. The turbine research background is introduced, including the work process, application rangeand the factors which affect the performance of turbine, and the basic structure of turbine isexpounded. Meanwhile, the research status both in the overseas and domestic are summarized. On thisbasis, the main job of this paper is illustrated.2. The parameter selection matching work of the refrigeration system under the design conditionis completed according to the design requirements for cold storage. In accordance with the designrequirements of the cooling turbine components in this system, the initial design of the radial-axialturbine is accomplished using one-dimensional method to determine the turbine basic geometry size;the method of inscribed circle is used to structure meridian lines, and by combining with thez rule central arced curve modeling method, the three-dimension design of impeller is achieved;the three-dimension model of nozzle ring and volute based on Bezier curve/surface are obtained.3. A certain radial-axial turbine is simulated on the base of the overview of numerical method.The contrastive results of the test and the numerical calculation under different number of grid showthat the numerical method is excellent to predict the performance of the radial-axial turbine.4. The influence of the number of impeller blades and the angle of nozzle vane on the turbineperformance are researched based on numerical calculation method. The impeller blades parametricdesign variables are improved combining with the Kriging approximation model, EI method andoptimization algorithm. The performance of the optimized turbine is predicted and the flowcharacteristic curve is drew, the influence of geometric parameters on the turbine performance are alsoanalyzed. 5. The research work of this article are summarized and the outlook for the subsequent researchdirection is put forward.