周向非均匀叶尖间隙对轴流压气机性能的影响

Effect of circumferential non-uniform tip clearance on performance of axial compressor

以跨声速单级轴流压气机为研究对象,通过改变转子外机匣椭圆度产生周向稳态非均匀叶尖间隙布局结构,在高转速压气机试验器上详细开展了周向非均匀叶尖间隙对压气机性能特性与稳定边界影响的试验研究。同时,结合转子叶尖间隙流场动态压力精细化测量,揭示了周向非均匀叶尖间隙触发压气机内部流动失稳的物理机制。试验结果表明:转子叶尖周向非均匀间隙对压气机流量、压比和效率基本没有产生影响,但对气动稳定性具有显著影响。随着转子机匣椭圆度增大,稳定工作边界逐渐向右下方偏移,压气机稳定工作范围不断减小;不同转速下,压气机稳定裕度损失程度并不相同,高转速工作区域的压气机稳定裕度损失程度要大于中低转速工作区域的;周向非均匀叶尖间隙会导致原有转子叶片气动负荷沿径向重新分布,弱化转子叶片尖部气动加功能力;设计转速时,相比于小间隙情况,大间隙下的泄漏涡与通道激波相互作用,使得相邻叶片压力面侧的高静压低速区域扩大,加重对转子通道的堵塞作用。

A steady circumferential non-uniform tip clearance structure is developed by changing the ellipticity of the rotor casing in a transonic single axial compressor.The effect of the circumferential non-uniform rotor tip clearance on the performance characteristics and stability working boundary of the compressor is experimented on a test facility of the high rotating speed compressor.The mechanism of the internal flow instability of the compressor induced by the circumferential non-uniform tip clearance is also presented by measuring the dynamic pressure flowfield parameters of the rotor tip clearance.The experimental results show that the circumferential non-uniform tip clearance has almost no effect on the mass flow,pressure ratio and adiabatic efficiency of the compressor,but it has significant effect on the aerodynamic stability of the compressor.As the ellipticity of the rotor casing increases,the stability operation range of the compressor decreases.The stability margin loss is higher at the high speed working area than that at the middle and low speed working areas.The circumferential non-uniform tip clearance can lead to radial redistribution of aerodynamic load of the compressor rotor blade,and then weaken the work capacity at the rotor blade tip area.Different from that with the small tip clearance,with the large tip clearance,the tip leakage vortex interacts with the passage shock at the design speed,and the high static pressure area at the pressure surface of the adjacent blade enlarges to result in more serious blocking effect on the rotor passage.