| Micro turbine engine has the advantages of light weight, large power and high energy density, so it has a broad application prospect in military and civil. Compressor-one of the key components almost takes the type of centrifugal or mixed flow. The pressure ratio of the majority of micro compressor is under 4. Increasing the pressure ratio can improve the thermal efficiency of the whole cycle, reduce the SFC and increase the thrust, so the goal of micro compressor development is to increase the tip speed to 500 m/s or more and make its pressure ratio over 4. Therefore, this paper investigate design methods of transonic micro mixed flow compressor whose pressure is over 4, by both numerical simulation and experiment, mainly in the following aspects:Firstly, the design framework of transonic micro impeller has been constructed based on 3-d flow field calculation, including the primary design, the meridional channel design and blade design etc. The effects of blade number, meridional channel, the distribution of loading and thickness of root, transonic blade profile of the tip, splitter blade and other parameters on the performance of the impeller flow field. According to the comparison and analysis, the design method or basic principle of each parameter is obtained. The micro impeller MJ-M1 was also designed whose diameter is 12cm. Numerical simulation shows that the highest pressure ratio of the impeller is over 5, and the efficiency is higher than 80% in most working conditions.Secondly, the inner flow field of the micro diffuser M0-A with the usual type was analyzed. The factors that affect the performance of micro diffuser are found, thus this thesis puts forward the conformal passage diffuser. And the 3D method of the diffuser is established regarding flow channel as design object, the influence of the passage area and angle distribution on the diffuser performance was investigated. It shows that the passage area distribution plays a more important role in diffuser performance than the passage angle, and the area distribution of slow increase after the first rapid increase can get higher performance. The experimental data shows that the M0-A is replaced with the conformal passage diffuser M0-C, the thrust of the engine at the maximum speed can increase 11%, the SFC can reduce by 9%. The early design of the diffuser MJ-M1 shows that it can get a higher total pressure recovery coefficient than 0.93 and the pressure coefficient is about 0.55.Thirdly, the designed compressor is used in MJ-M1 micro turbine engine. After improving the propane gas supply method, the matching relationship between combustion chamber and the other parts, the rotor shaft system and the engine casing, the assembly and debugging of MJ-M1 engine is successfully completed. The speed of engine achieved 120000r/min, the first stage objective of thrust (12kgf) is obtained. Finally, the compressor was tested in the running micro turbine engine by changing the nozzle outlet area. The impeller pressure ratio characteristics, the total pressure recovery coefficient of diffuser and the static pressure distribution of impeller were measured. Experiment show that the pressure ratio of MJ-M1 impeller exceeds 3.2 at 80% rotation speed. The results of experiment and calculation agreed well, the reliability of numerical simulation is verified.
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