| Inlet guide vane angle adjusting is a common method for compressor flow control.The inlet guide vane angle change leads to the change of rotor inlet flow velocity at certain speed in both direction and amplitude,which affects performance and radiation noise of the compressor.Therefore,it is vital to study the flow field and inlet noise characteristics of compressor with variable inlet guide vane angle.Multiple speeds and variable inlet guide vane angles of a 1.5-stage transonic axial-flow compressor was numerically calculated in nonlinear harmonic method.Based on a large number of simulation results,the flow characteristics of the compressor were studied in details from the following aspects: the flow in the rotor blade passage,the tip clearance flow,rotor/stator interactions and the blade surface load.The results show that when the guide vane deflects in negative direction,the inlet flow of the compressor increases.Both the high pressure area of the pressure surface and the low pressure area of the suction surface expand and squeeze the separated flow at the leading edge of the rotor blade.Moreover,the surface pressure along the chord length of rotor blade fluctuates sharply under the transonic condition caused by large guide vane angle deflection.In this paper,the compressor inlet noise test with variable inlet guide vane angles was carried out.Features including inlet/exhaust pressure levels,the BPF characteristics of inlet noise,inlet noise spectrum and tip clearance flow field under different inlet guide vane angles were systematically studied.With the negative increase of inlet guide vane angle,the pressure level of inlet noise increases and the low BPF of intake noise gradually dominates.The inlet noise spectrum mainly includes broadband noise,nonsynchronous discrete noise and shock wave noise,which are caused by rotor/stator interaction,tip clearance vortex migration under low flow condition and transonic shock wave respectively. |
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