Research On The Method Of Low-speed Model Testing For High Pressure Compressor

High pressure compressor (HPC) is a principal part of the aero turbo-engine; the function of HPC can directly determine the overall performance of the engine. Because of the shortage of sufficient understanding of the actual flow domain within the HPC, its aerodynamic design has always been a challenge to the researchers and engineers. Low-speed model testing is one of the key technologies to approach the flow field details of HPC and then improve its aerodynamic properties. In this paper, the method of the low-speed model testing to the HPC has been studied and analyzed; focus on the"similarity criteria"which reflects the high-to-low speed transformation process, this paper has investigated the methodology of the aerodynamic design process and local flow measurement corresponding to the low-speed compressor, which also verify the reliability of those'similarity criteria'through the experimental results. The main research work can be itemized into five aspects as below:(1) Establish"similarity criteria". With the reference of the foreign researchers'work, this paper presents the similarity criteria adopted according to the characteristics of the low-speed model testing. The rationality of the similarity criteria has been explored and analyzed. Then the reasonable program of the low-speed model testing has been determined.(2) Establish Simulation goals based on the"similarity criteria". Firstly, full three-dimensional viscous flow simulation has been carried out to a multi-stage HPC by commercial NUMECA software. Then in order to verify the reliability of the simulation, the influence of different forms of the grid, the grid nodes, the first layer grid thickness and calculate parameters such as the working fluid used, have been investigated, as well as the cascade experiment of the mid-span blade of the fifth stage stator to further verifies the simulation reliability. Finally a detailed flow filed analysis of the fourth and fifth stage has been performed. By comparing these two stages'flow field characteristics, the stage to be simulated of the HPC has been determined, which defined the goal of low-speed simulation.(3) Large-scale low-speed model compressor design and build low-speed test bed. Firstly, based on"similarity criteria", the the aerodynamic design of the low-speed compressor (LSC) has been completed by overall parameter design, S2 stream surface design, iterative calculation of S1 stream surface and blade shaping, as well as the full three-dimensional numerical simulation of viscous flow. The results of numerical simulation show that flow features of the HPC and LSC matched well, which preliminary proved the reliability of the low-speed model compressor's design. Then the structural design of the low-speed compressor, and low-speed compressor test rig settlement have been completed, meet the requirements of detailed flow field measurements.(4) Investigate the testing contents and methods of the low-speed model compressor measurement; establish the testing scheme; set up the low-speed compressor test rig and testing system. Firstly, determine the testing contents of the low-speed compressor testing according to the"similarity criteria"; then explored the test methods and establish the testing scheme for the testing contents. Finally, the structural design of the low-speed model compressor has been completed. The related test-bed and the measurement system have been set up, with satisfaction to measurement requirements.(5) Detailed flow field measurement of the low-speed model compressor. Comprehensive experimental measurements have been carried out, including: the whole machine and the simulation stage compressor performance measurement; Rotor and stator exit flow were measured by a four-hole probe. Stator inner flow field was measured by seven"L"type five-hole probes for the different test sections, and stator blade surface pressure was measured by surface pressure taps. Particle image velocimetry (PIV) was utilized to investigate the rotor inner flow field.The results of 3D flow calculations and experiments shown that the both the primary and secondary flow features can be successfully reproduced in the low speed environment. The pressure distributions on the stator blade and flow angles in the low speed compressor were consistent to the high pressure compressor. So the reliability of"similarity criteria"carried out in thsis paper has been proved.In the absence of spraying coatings due to mechanical processing, the actual tip clearance of rotor blade is bigger than the design value. Thus results in the low-speed model compressor did not fully represent the flow domain in the tip area of the HPC, which is a deficiency of this paper.