基于探针管路动态修正的压气机动态总压测试

Measurements on compressor dynamic total pressure with dynamic correction of pneumatic probe

为方便安全地获取压气机内部多点动态总压信号,采用气动探针将测点压力引出,并通过动态修正还原测点处的压力信号。利用爆破气球装置产生的向下阶跃输入信号和探针响应输出信号,辨识得到探针管路的离散传递函数模型,以此来修正测量信号,获得测点真实压力。所用标定方法能够实现1000Hz以内信号的动态修正,探针信号经过修正后能够消除相位延迟,且管路谐振效应对信号的放大作用显著减小。压气机动态总压测试结果表明:随着进气流量的减小,转子进口叶片通过频率信号幅值逐渐增大,静子出口宽频扰动增强,在近失速点宽频扰动最大;压气机突尖型旋转失速先兆首先出现在转子叶片前缘叶顶附近,而后向叶根方向迅速扩展,并形成全叶高范围的旋转失速团,完全发展的失速团传播速度约为30%转子转速。

The pressure signals at measurement points are extracted via pneumatic probes and restored by dynamic correction in order to obtain the multi-point dynamic total pressures in the compressor conveniently and safely.The discrete transfer function models are used to correct the measured signals and obtain the real pressures at the measurement points.These models are identified by the downward step input signals and probe response output signals generated by the burst balloon device.It is proved that the method is reliable for the signal dynamic correction within 1000Hz,the phase delay can be eliminated virtually and the tube resonance effect on the signal amplification can be reduced obviously after correction of the probe signal.The measurement results of dynamic total pressure in compressor show that the signal amplitude of blade passing frequency at rotor inlet increases gradually with the decrease of mass flow rate,meanwhile,the broadband disturbance intensity at stator outlet increases and reaches the maximum at the near rotating stall point.In addition,the spike-type rotating stall inception first appears near the tip of the rotor blade leading edge,then expands rapidly to the blade root and develops into a full-span rotating stall cell.The propagation speed of the fully developed stall cell is about 30%of the rotor rotating speed.