Investigation On The Design Model Of Aerodynamic Parameters For Highly-loaded Turbine

From the current situation and future trend in development on the turbine, it is important to increase turbine load and reduce the rows of turbine blades for the upgraded performance of aircraft engines. However, a series of new research themes need to be overcome for the highly-loaded turbine. Accurate and efficient design on the aerodynamic parameters is one of these problems. The optimization on the aerodynamic parameters is significant for the design of highly-loaded turbine. In this paper, the selected criterion of aerodynamic parameters for highly-loaded turbine is investigated on the basis of former research. The main contents and conclusions are listed as follows.The design model of aerodynamic parameters for highly-loaded turbine has been established based on the efficiency equation with improved Kacker&Okapuu loss model. And the sensitivity analysis of aerodynamic parameters is performed to study the effects on the efficiency of the turbine stage by means of the method of orthogonal experimental design. The results indicate that the reaction and axial velocity ratio have more remarkable influence on the stage efficiency compared with other aerodynamic parameters, including solidity, hub-to-tip ratio, aspect ratio and the ratio of trailing edge thickness to throat width. And the effect of above mentioned four aerodynamic parameters on the stage efficiency is not very prominent for the range of1.2-1.8solidity,0.3-0.9hub-to-tip ratio,0.8-1.7aspect ratio and0.08-0.14ratio of trailing edge thickness to throat width. It can be ignored in the design of aerodynamic parameters.The accuracy on the design model of aerodynamic parameters for highly-loaded turbine has been verified by the comparison with experimental data. And the effects of loading factor, flow coefficient, reaction and axial velocity ratio on the stage efficiency are analyzed using the model in a highly-loaded transonic turbine with2.6loading factor and5.0expansion ratio at design condition. A reference diagram used to select appropriate aerodynamic parameter for highly-loaded turbine has been obtained, which is effective at the range of1.2-1.8solidity,0.3-0.9hub-to-tip ratio,0.8-1.7aspect ratio,0.08-0.14ratio of trailing edge thickness to throat width and2.0-4.0loading factor.The aerodynamic design parameters of a highly-loaded transonic turbine are determined according to the reference diagram. And the aerodynamic design of the turbine is finished by means of3D design program. The flow characteristics of the turbine are also investigated by a3D numerical simulation. Through the comparison between the3D numerical data and the analyzed results of the design model, the effectiveness of the selected criterion of aerodynamic parameters for highly-loaded turbine is validated. And it also indicates that the model of aerodynamic parameters in this paper is suitable for the design of highly-loaded turbines.