Research On Thr Applicability Of Curved Blade In High Subsonic Compressor Cascade Design

As a method to improve the aerodynamic performance of a compressor,curved blade has been widely used in design.In addition,in the early design of the compressor,solidity is also a crucial parameter.Therefore,in this paper,by changing the camber angle and meridian constriction ratio,three diffusion environment of cascade with the camber angle of 40°,50°and meridian constriction ratio of 0.8 were designed.Considering the solidity,the application conditions of curved blade in high-subsonic cascade were studied,and the influence relationship between the solidity and curved blade in cascade with different diffusion environments was discussed,and the optimum matching principle of solidity and curved blade were found.All the above studies were based on the case of minimum loss incidence.First,the incidence characteristics of three cascades were studied,including total pressure loss,diffusion factor and deviation angle.Because of the subsequent study in this paper is in the case of minimum loss of incidence,the range of incidence near the reference condition is only analyzed for the two cascades with the camber angle of 40°,which doesn't involve positive or negative stall angle.However,when the camber angle is 50°,the cascade loading is very high,leading to a large separation scale.In order to study the effect of curved blade under varying operating conditions,the research range is extended to positive and negative stalling angle.The results show that curved blade enlarges the stall margin and improves the diffusion capacity.Secondly,the influence of solidity and curved blade on diffusion ability in different cascades was analyzed.The results show that,from the perspective of static pressure rise coefficient and flow turning angle,the influence of solidity is higher than that of bowed angle in the cascade with a contraction ratio of 0.8 and camber angle of 40°.When the contraction ratio is 0.9,the effect of bowed angle is greater than that of solidity.In the cascade with a camber angle of 50°,the influence of solidity and bowed angle is similar.According to the analysis of diffusion factor,the solidity in three cascades has a weak influence on diffuser factor.When the cascade lie in a large diffusion environment(?=50°),the diffusion factor increases significantly with the increase of bowed angle.Finally,the effects of solidity and curved blade on flow loss in different cascades are discussed,and the benefits of the curved blade are analyzed.The results show that,when Dimin?0.5,the curved blade has good benefits,which indicates that the diffusion factor of the cascade is required if the curved blade wants to play a role in the high-subsonic diffusion cascade.In the cascade with the camber angle of 50°,Dimin?0.54,the diffusion capacity is higher,and the benefits of the curved blade is up to 15%.Therefore,in the high-subsonic diffusion cascade,the application condition of curved blade is large geometric camber Angle.At this time,for a given Dimin,the reasonable matching between the solidity and bowed angle is:the combination of positive bowed angle of 20°and solidity of 1.4 reaches the minimum loss.And if the matching principle is positive bowed angle of 30°and solidity of 2.2,the cascade has a high static pressure rise coefficient.