Experimental Study On Aerodynamic Performance In The Stator Cascade Of High Power Ground Gas Turbine Compressor

In order to study the aerodynamic performance and the physical mechanism of flow loss in the seventh stator cascade of the 9FA type heavy duty gas turbine compressor,blowing tests of three sets of rectangular cascades based on the blade profile of the root,middle and top span and fan cascades with 7 blades corresponding to the static annular cascades were made.Due to the limitation of the low speed wind tunnel,the experiment can only be done under the low Maher number.Although the experimental results can not fully reflect the actual flow of the real cascade,the design technology of diffuser blade and static cascades can be known to a certain extent and useful reference for the retrofit design can be provided by analogy.Measurements of inlet and outlet flow field of middle blade in rectangular cascades based on the blade profile of 0.1,0.5,0.9 relative blade height in static blade were made under the incidence angle of 0°,±3.5o,±7o by using the five hole probe bundle.Static pressure measuring hole were arranged at middle blade profile of the blade located in the middle of intercept direction in every sets of rectangular cascades.Then the static pressure distribution on the pressure side and suction side of the above-mentioned three blades profile can be measured.On this foundation,we chose fan blade cascades with seven blades obtained by geometric amplification of real static blades as experimental model.Then the distribution of aerodynamic parameters along the blade height and pitch was measured before and after the cascade.At the same time,the root of the middle blade(0.1 blade height),the middle(the height of the 0.5 blade)and the top(the height of the 0.9 blade)were also provided with the static pressure measuring hole in order to measure the static pressure distribution along the blade profile of the three blades.The experimental results show that turning angle of root,middle and top profile in the seventh stator cascade of 9FA type heavy duty gas turbine compressor are basically identical.Their blade profile loss are about 3.2%.The increase of flow loss caused by the incidence angle of ±7o are only 1.58% and 0.717%.As for the static pressure distribution along blade profile at three blade height,the changes of incidence angle only causes pressure fluctuations in the pressure side and the suction side of the blade before 0.3 axial chord,without affecting the value of the static pressure distribution along blade profile after the 0.3 axial chord.Comparing with the middle blade geometric outlet angle,the maximum change rate of outlet angle at three blade height are all less than 3%.When selecting different profile types of different blade height,the designer the authors consider that the uniformity of the flow parameters along the blade height should be taken into account when the profile loss is reduced.The results of fan cascades experiment show that the total pressure loss coefficient is 9.76% under the incidence angle of 0,the increases of the positive incidence angle(+7 degrees)and negative incidence(-7 degrees)increased are 8.5% and 19.7% respectively.On one hand,the above-mentioned result show that in the compressor cascade without tip clearance,secondary flow losses is up to 2/3;on the other hand,it is indicated that the static cascade of heavy duty gas turbine has good adaptability.