Three-dimensional Aerodynamic Design And Experiment Investigation Of Transonic Compressor Stator

With the development of modern high-performance compressors towards transonic,high load and small aspect ratio,total pressure ratio and single-stage toatal pressure ratio of compressor both have been significantly improved.Under this development trend the pressure gradient inside the cascade flow path has been strengthened,making the flow more prone to separate and leading to greater energy loss.In this thesis,a transonic compressor stator was optimized from the aspects of blade profiles and stacking line.A transonic single-stage compressor was numerically studied at different rotational speeds.Results showed that the flow separation in the corner between the suction surface of stator and casing at low mass flow rate conditions was the key factor that cause compressor stall and impediment to the compressor performance improvement.To improve the flow structure inside the stator,firstly,the blade profiles of the stator were optimized.The blade profiles of 5%,50%and 90%blade height were extracted and transformed into 2D profiles.Balde profile reconstruction based on bi-cubic polynomials mean camber line and thickness distribution was achieved.The mathematical mapping between the geometry parameters and the aerodynamic performance of the 2D profiles was established by the use of design of experiment and the artificial neural network,and then global optimization was carried out to obtain the optimized 2D profiles.Linear cascade experiments based on these 2D profiles were conducted.Results showed that,the available incidence range of optimum profiles of 5%and 90%blade height both move to the negative incidence direction,maintainning the range of the available incidence angle,elevating the performance of 2D profiles at negative incidences.The optimum profile of 50%blade height gained a significant reduction of profile loss,and the minimum loss incidence was changed from-2° to 0°.Optimized stator gained by returning the optimized 2D profiles at 5%,50%and 90%blade height to the 3D stator enabled the compressor stage stall at a lower flow rate and improved the stall margin.Secondly,optimization of stator stacking line was performed.Relationship between stacking parameters and stage performance was constructed,and then global optimization was accomplished.With the stacking line optimized stator,the stage total pressure ratio and adiabatic efficiency between the design point and the near stall point had been significantly improved,and the near stall flow rate had been reduced.At the same time,the performance between the design point and the choke point had basically remained unchanged.A final optimized stator which combines the two optimization results was constructed,and the performance of the compressor stage had been comprehensively improved,which incicated that the two methods of stator optimization were relatively independent.The sample space was effectively reduced,which provided a new direction for compressor stator optimization.A new stage with preliminary optimized rotor and the final optimized stator was built up.Compared with the stage with preliminary optimized rotor and the original stator,in the new stage,the performance improvement between choke point and design point was maintained,while the adiabatic efficiency and the total pressure ratio between design point and near stall point were improved,and the stall margin was also improved.It proved that the optimized stator plays a positive role in the control of flow and achieved the expected result.