Inlet distortion  is a subject of increasing interest in compressors over the last years. Circumferential inhomogenities can significantly influence the behavior and the aeroelastic response of transsonic  compressors in gas turbines in the field of airplane propulsion as well as power production. The circumferential inhomogenities can result from boundary layer ingestion as planed in many future airplane concepts or from restrictions of the space available leading to short geometrically unfavorable intakes. As modern front rows of axial compressors react more and more sensitive to inhomogenities because of the thinner profiles in the transsonic flow regime, understanding the reactions is vital. Therefore an experimental investigation of the inlet distortion effect on a 4,5 stage axial transsonic compressor which is representative of the front stages of a modern high pressure compressor, called Rig250, has been investigated on the compressor test rig at DLR Cologne.

The inhomogenity is a total pressure distortion which is applied to the inflow upstream of the strut and the swan neck. The distortion is achieved by a perforated metal plate which can be rotated by 360° at its position. Thereby traverse measurements are possible, which allow a better understanding of the effects of the flow as the sensor positions on the casing and on the blades and vanes are fixed. As these traverses took longer time for measuring only some points are measured with traverses. The compressor has been tested with and without this inlet distortion to get a direct comparison. On the compressor map several speed lines up to surge have been tested and show a moderate influence on the surge margin.


Experimental Investigation of Inlet Distortion in a 4.5-Stage Axial Compressor

Division / Sponsor:
International Gas Turbine Institute (IGTI)

Paper Proceedings: https://asmedigitalcollection.asme.org/GT/GT2020/volume/84058

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