Investigation Of The Effects Of 3d Blade Design On A Low Flow Rate Turbine

In the development of helicopters, the performance of almost all of them depends on the turboshaft engine, in which turbine plays a key part. And the improvement of turboshaft engine and helicopter greatly relies on the performance of turbine. Compared with other aircraft gas turbines, turboshaft has the characteristics of low flow rate, high rotating speed and relatively small size, leading to complex flow conditions, low aspect ratio and thick boundary layer. The high proportion of boundary layer in cascade intensified the secondary flow and the accumulation of low energy fluid near the endwalls, which increases the losses.A power turbine in turboshaft has been investigated in this paper. The bowed and twisted stator has been utilized in first stage and compared with a normal blade with straight stacking line. It can be seen that several benefits are brought by using bowed and twisted stator and the reasons why an improvement of efficiency and flow condition have been obtained are deeply analyzed from the aspects of the development of passage vortex and the spanwise distribution of pitchwise massaveraged efficiency and density flow.Furthermore, the effect of different bowed angles of the stator on the flow condition of both stator and rotor has been investigated. And the variation of aerodynamic parameters and the matching between stator and rotor has been studied. On the basis of optimized bowed stator, several modified stators with different blade turning angles has been made to reveal the mechanism of twisted method. The twisted stator has a distinctively effect on rotor. Then the changes of efficiency and matching of stator and rotor introduced by bowed and twisted blade has been analyzed.Finally, considering the different methods adopted when dealing with the interface between stator and rotor, unsteady numerical investigation of bowed and twisted stator has been carried out and compared with the steady results. From the comparison, it can be seen how secondary flow and passage vortex develop are different in the two researching methods.From the results of this paper, the way of utilizing bowed and twisted blade in a low flow rate turboshaft engine has been obtained. And researchers and designers may get some ideas from the paper when designing the turbine in a turboshaft engine.