Swept Blade And Aft-loaded Profile Design Technique Research On Micro Axial Turbine

In recent years, micro turbine engine needs higher performance, higher energy efficiencyfeatures.As a core part of the micro turbine engine, it needs to have high efficiency, high flow capacity,light weight characteristics etc. But with the size reduction, the impact of miniaturization effect makesa significant increase in micro-axial turbine losses and a significant change of the loss constitutesproportion, which causing micro-turbine efficiency is far lower than conventional turbines, of whichsecondary flow losses increases significantly and then occupies a dominant position. For this reason,study of blade swept and after loaded blade design technology was carried out on the micro axial flowturbine of MTE17, which developed by micro turbine engine institute of Nanjing University ofAeronautics and Astronautics, aiming at reducing its secondary flow losses. Finally, the most suitableswept blade and the after loaded blade were designed. The main contents of this paper include:1. Launched a micro-axial turbine stator swept blade design technology research, firstly byanalyzing the flow in the stator channel, then considered the affect mechanism, a root swept treatmentwas done eventually. A comparison of the effect of different swept form on the flow field wasdoneand then got the better swept form. At the meantime, analyzing the influence on passagesecondary flow, flow losses and the downstream flow of different swept angle(20°,30°,40°) and sweptheight(0.2,0.5,0.8). The result shows that as swept angle increases, the improving effect at the rootend wall area is more obvious. The loss of the central channel is an increasing trend, while the sweptangle exceeds20°, the improvement magnitude of the loss increasing rate was faster than the bladeroot. For swept height, its effect is similar to the swept angle, but when swept height is more than0.5,the effect of improving at root become not obvious. Eventually, through the above research andultimately determine the best fit swept airfoil for this turbine stage that the swept angle20°, the sweptheight0.5.2. The results show that: the angle of attack on the leading edge influence the inlet loads a lot. Theblade transverse load of about10%of the axial chord length can be reduced by increasing the leadingedge radius. The camber is the main factor affecting the load distribution. With the camber line ofmaximum curvature position move backwards, the load center of gravity shift back gradually, andthen the blade root secondary flow strength is weakened, so the total losses get lower, the optimumposition of maximum curvature of about38%of the axial chord length. Airfoil thickness distributionthen plays a supporting role, and with the decrease of profile curvature, blade load is gradually reduced, and appropriately increase the thickness of the airfoil blade performance does not degrade.Only when these four geometrical factors working together, will the typical after load characteristicsbe made to the fact. In the end, this paper identified the most suitable after load micro axial turbine.