Compressor stability detection on a turboshaft engine with a hybrid axi-centrifugal compressor

摘要

A compressor stability measure rooted in the unsteady characteristics of the flow field in the tip region of a compressor rotor has been previously developed. This measure, called the correlation measure, has been used to successfully control a laboratory axial compressor facility, and has also been demonstrated on a modern gas turbine engine. The present work is the first application of this measure to a hybrid axi-centrifugal compressor. Experimental studies have been carried out on a small turboshaft gas turbine (GE-T700) at NASA Glenn's Engine Components Research Lab. The experiments conducted include steady-state compressor operation at multiple speeds and transient operation with acceleration of the compressor spool. The compressor operating line is raised by injecting external air through bleed ports downstream of the compressor. The results show that the measure can successfully detect the limit of stable compressor operation, prior to the onset of instabilities. Within the limitations of the test facility, proof-of-concept closed-loop control has demonstrated the effectiveness of fuel actuation for compressor stall avoidance. In particular, it has been determined that such a control can be implemented using existing fuel actuators.