分体滑动导叶可调涡轮激波与载荷波动机制

Mechanism of Shock and Load Fluctuation of Variable Nozzle Turbines with Split Sliding Guide Vanes

针对某柴油机用可调涡轮在低速工况下的低效强激波特征,提出并设计了一种分体滑动导叶,并在10%、40%和100%3个典型开度下进行了定常/非定常数值计算。结果表明:分体滑动导叶在小开度下可实现对间隙泄漏流动的有效抑制,大幅度提高涡轮效率;在10%开度下,分体滑动导叶提高了涡轮10%的峰值效率,同时涡轮效率在40%和全开工况下也有不同程度的提高。此外,通过合理设计转静间距,分体滑动导叶尾缘激波被大幅度削弱。导叶间隙泄漏流和尾缘激波的抑制可有效弱化转子定子干涉强度,降低下游转子叶片表面载荷波动幅值,提高转子叶片的可靠性。

In view of the low efficiency and strong shock characteristics of the variable nozzle turbines in a diesel engine at low speed,a split sliding guide vane was proposed and designed,and the steady/unsteady numerical calculations were carried out under three typical nozzle openings of 10%,40%and 100%.Results show that the split sliding guide vanes may effectively restrain the clearance leakage flows and greatly improve turbine efficiency under the small nozzle openings.Under the conditions of 10%opening,the turbine peak efficiency is improved by 10%,besides,turbine efficiency is also improved to different degrees under other openings.At the same time,the trailing edge shocks of the split sliding guide vanes are greatly weakened by the reasonable design of rotor-stator spacing.The weakening of guide blade clearance leakage flows and trailing edge shocks reduces the rotor-stator interference,thus weakens the intensity of load fluctuation on downstream rotor blades and increases the reliability of rotor blades.