叶尖间隙对跨声速压气机叶片气动阻尼的影响

为了分析叶尖间隙对压气机气动阻尼的影响,基于相位延迟边界条件,建立了跨声速转子的气动阻尼计算模型,研究叶尖间隙对其流场及气动阻尼的影响。计算该转子在设计间隙条件下的气动性能、叶片模态以及颤振边界,和实验数据吻合较好,比较不同叶尖间隙(1.6%,3.2%,5.0%叶尖弦长)的转子气动性能,发现间隙增加使转子效率和压比均有显著的下降;对叶片表面非定常压力研究表明,叶片非定常压力对叶片振动的响应具有强三维特性,同时叶片间相位角(IBPA)和叶尖间隙流对其有显著的影响,由于叶尖间隙增加使叶尖流动的影响加强,导致叶尖区域由于振动造成的一阶谐波压力幅值相对减小,大间隙趋于恶化压力面的稳定性而对吸力面的影响在不同的叶片间相位角时不同;对于气动阻尼,在不同的叶片间相位角区域,叶尖间隙对其影响有显著的差异,甚至会产生截然相反的规律,特别是在设计状态,对于该转子,大间隙提高了叶片最不稳定状态的气动阻尼。

Influence of blade tip clearance on blade aerodynamic damping in transonic compressor

Based on transonic compressor flutter test rotor, an efficient aerodynamic damping computational model using phased lagged boundary conditions is established to analyze the influence of blade tip clearance on compressor flow field and aerodynamic damping. Numerical results of rotor aerodynamic performance, blade mode and flutter boundary analysis with design tip clearance are closely consistent with the experimental results. The rotor aerodynamic performances with different tip clearances (1.6%, 3.2% and 5.0% tip chord) show that tip flows can significantly reduce the total pressure ratio and efficiency of rotor. Unsteady pressure results on blade surface indicate that the unsteady flow response is a strong three-dimensional nature. Inter-blade phase angle (IBPA) and tip clearance are crucial factors influencing blade surface unsteady pressure. The first harmonic pressure amplitude in blade tip region which is associated with blade vibration relatively weakens due to the enhancement of blade tip flow with the increase of blade tip clearance. The stability of pressure surface tends to worsen due to increasing blade tip clearance. However, the influence of blade tip clearance on suction surface depends on inter-blade phase angle. The influence of blade tip clearance on blade aerodynamic damping has significant differences at different inter-blade phase angle, even an inverse relationship. Specifically, the aerodynamic damping is enhanced with increasing blade tip clearance at the least stable inter-blade phase angle.