Study On Airfoil Design And Influence Of Tip Clearance Of High Subsonic Micro Axial Turbine

The micro-turbine engine can meet future demand of mini aircraft for high energy storagedensity, high power thrust-weight ratio of the power plant, which increase the flight distance andthe load bomb weight. As its main core components, micro axial turbine has been widely used asthe high through-flow capacity and light quality characteristics, which can heighten thethrust-weight ratio. At present, there isn`t a complete system on the study of micro axial turbine,the design theory is still with reference to the conventional scale turbine. So carrying out a study onthe flow characteristics and design technology of micro axial turbine, this is of great significance toimprove performance of the turbine stage and engine. In this paper, based on the MTE-D engineprototype, the micro axial flow turbine flow characteristics and design technology research wasstudied by means of numerical simulation. And the technical effectiveness of the micro axial flowturbine was verified by the overall tests. The main work is as follows:1. The study of the flow characteristics of micro axial flow turbine that cm in size was carriedout on analyzing the effect of size effect on turbine performance, flow structure and losscomposing. As a result, micro axial turbine loses more because of its smaller size, faster speed,shorter blades and thicker boundary layer. As a result of that, the transverse secondary flow and theradial secondary flow loss approaching the hub and the engine casing increase remarkable. The lossof stator and rotor increase respectively31%,12%.2. Study of the solidity of blades was carried out to analyzing the performance, flow structure,loss variation law of the stator and rotor. Studies showed that aiming at high subsoniccentimeter-level micro axial flow turbine, the stator for better range of solidity is1.0~1.3, which issmaller than conventional axial flow turbine, yet the rotor for better range of solidity is1.4~1.7.3. The design and research on high subsonic axial flow turbine blade based on the MTE-Dmicro engine prototype was carried out, the twisting law for guide vane outlet that suitable formicro axial flow turbine was made out, a preferred rotor blade angle distribution and axial chordlength was chosen, and completed the design of MTE-D prototype for high subsonic axial flowturbine of78.4mm diameter simultaneously, the design performance are that the pressure drop ratiowas2.12, the flow rate was0.358kg/s, the efficiency was0.883, the unit output power was203.7kJ/kg.4. Study was carried out on the flow characteristics and the influence of gap size on the performance of high subsonic axial flow turbine, which analyzed the influence of gap size onleakage loss, leakage vortex formation position, motion track, rotor flow field structure, andconfirmed the influence law of gap size on high subsonic micro axial flow turbine performance.5. The micro axial flow turbine was designed in this article to the MTE-D micro engine, andthe engine ground tests was completed successfully, the maximum speed in the tests is108krpm(90%of design speed), the effective thrust118N. The suitable gap size for tests and the micro axialflow turbine engine performance test tests projects of different gap size were confirmed. Testprocedure, measurement plan and data processing method were all planned.