Optimization Of High Subsonic Compressor Cascade And Research On The Flow Mechanism Investigation

With the thrust-weight ratio of aero engine increasing year by year,the demand of compressor load become higher and higher.The load increase of single stage compressor has great influence on the aero engine overall performance improvement.But the increasing load makes the flow path lateral pressure gradient increase to cause boundary layer which becomes thickening separate more easily at suction side under the adverse pressure gradient condition.And it's more difficult and complex to control the boundary layer and secondary flow where great attention must be paid.So,It is of great significance to develop a cascade of high load compressor.The dissertation takes the second stage stator cascade of a three-stage high load compressor as the research object,firstly carries out blade profile optimization at the mid span location,then gets prismatic blade through the radial stacking of the newly designed blade profile and observe its 3D flow performance,and finally performs the curved blade profiling and study the flow control effect of 3-D curved blade.Firstly,the dissertation carries out numerical method validation of 2-D blade profile.And the result shows the correctness of the calculation method and turbulent model.Based on this validation work,grid independent validation is then executed.The result shows the grid number has no longer influence on the calculation when the grid number is larger than 1.73 million.Above all,the numerical calculation method in the dissertation is of great credibility.Then,the dissertation uses ISIGHT software platform to carry out blade profile optimization at the mid span location with the optimization objectives of total pressure loss coefficient and air flow turning angle.Through reasonable control of pressure field distribution for the optimized blade,the operating range and stall margin are widened significantly,and the aerodynamic performance is improved within all operating conditions,and the blade cascade loss is reduced significantly.In 3-D flow field,the optimized cascade has a smaller circumfluence zone and lower circumfluence degree at hub and shroud corner region.The loss along the whole span is smaller,compressing capability is greater,and the operating range is wider than the prototype cascade.Finally,orthogonal design method is chosen to carry out curved blade design on the basis of the optimized prismatic blade.Though this method and after several trials,the curved blade satisfies the design target is obtained and the trial time is reduced significantly.The result indicates that total pressure loss coefficient has a maximum reduce of 2.5% compared with the optimized prismatic blade at the large positive incidence condition when a curved method of negative curved profiling at hub and positive curved profiling at shroud is applied.