| As the core equipment in the field of power generation and drive,heavy-duty gas turbine has the advantages of high power,high efficiency and low emission,which is of great significance for China to adjust the energy structure and realize the clean and low-carbon development.The transonic inlet stage is widely adopted in the axial flow compressor,which is the key component of heavy-duty gas turbine.At present,the design of transonic stage has become the key technical ways to improve compressor pressurization ability and load level.However,due to the existence of shock wave,the internal flow field of transonic stage is very complex,so it is urgent to further study the internal flow mechanism.In this paper,the inlet 1.5-stage transonic compressor from the multi-stage axial compressor of an F-class heavy-duty gas turbine is taken as the research object.The steady numerical simulation is carried out for the original geometry and the scaled modeling geometry respectively.The aerodynamic characteristics and the internal transonic flow field mechanism are analyzed.The aerodynamic test is carried out on the scaled 1.5-stage transonic compressor,and the steady aerodynamic performance and the dynamic pressure signal near the rotor tip casing under variable speed and IGV angle are measured.The comparison and analysis between the numerical calculation results and test results verify the numerical method.In terms of numerical simulation,firstly,the performance characteristics of the original1.5-stage compressor with variable IGV angles at design speed are calculated,and the detailed flow field is analyzed at the peak efficiency point of each IGV angle.The results show that with the increase of IGV angle,the choke flow increases gradually,and the performance curve of total pressure ratio moves to the upper right as a whole.The peak efficiency increases first and then decreases.The reason is that the IGV angle will affect the load and loss of rotor and stator and the load distribution between rotor and stator in the transonic stage.The comprehensive effect of IGV,rotor and stator channel losses causes the peak efficiency of the whole stage to increase first and then decrease with the increase of IGV angle.In addition,by comparing the calculation characteristics of the original and the scaled 1.5-stage compressor under design conditions,it is found that the total pressure ratio and isentropic efficiency at the design point decrease by 1.723% and 2.232% respectively after scaling.The main reason for the performance degradation of the scaled 1.5-stage compressor is the nonsimilarity of the tip clearance(both the original and the scaled clearance are 0.4 mm).After scaling,the tip clearance leakage is significantly increased relative to the mainstream,and the flow blockage effect caused by the leakage vortex is stronger.In terms of aerodynamic test,the steady test characteristics with variable speed and IGV angle are compared with those of numerical calculation.The performances of total pressure ratio under 90% speeds agree well with each other,while the total pressure ratio measured at100% speed is slightly higher than the calculation results.At the same time,due to the loss of mechanical drive,the torque efficiency measured in the test is less than the calculation results.But the error analysis of the test characteristics under the design conditions makes up the gap between the test and numerical results to some extent.On the other hand,through the analysis of the dynamic pressure signals measured at 100% and 80% speeds,it is found that the stall inception types of the 1.5-stage compressor at these two speeds are both spike,and the propagation velocity of the stall cell is about 50% rotor speed.During the throttling process,the tip clearance leakage flow intensity increases,indicating that the spike type stall inception is related with the unsteady tip clearance leakage flow. |
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