Qualitative influence of blade machining deviation on cascade critical angle of attack
In order to study the relationship between blade machining deviation and compressor stability,and establish the quantitative correlation between common machining accuracy and compressor working range,the middle section of two-stage stator blades of multi-stage high-load axial compressor was taken initially as the research object,a reduced order model of blade surface geometric uncertainty was constructed,and the deviation blade profile database under three kinds of common machining accuracy was generated.Combined with the relationship between the neural network prediction uncertainty input variables and the range of critical cascade angle of attack,pseudo-Monte Carlo method was used to generate a large number of samples and carry out statistical analysis.The results showed that,compared with the prototype,the introduction of machining deviation decreased the cascade positive critical angle of attack,and increased the negative critical angle of attack.Therefore,the range of critical angle of attack decreased,and the aerodynamic performance deteriorated more than the prototype.Taking the positive critical angle of attack as an example,when the machining accuracy increased from level 2 to level 1,the mean value of the positive critical angle of attack decreased from 7.485 8° to 7.557 1°,and the sensitive part of the blade changed from the whole blade area to the leading edge and the front half chord length,and the influence trend of the increase or decrease of the profile on the critical angle of attack also changed.Given the statistical quantification from above analysis results,the research conclusions could provide a theoretical basis for the design and optimization of 3D cascades or compressor rotors in the future,thus further saving the machining cost.
machining deviationmachining accuracycritical angle of attacksensibilityaerodynamic performance
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