Real-Time Wireless Pressure Sensing System for Stall and Loading Measurements in the Rotating Frame of Reference for a Low Speed Compressor

In this paper the fabrication and characterization of a novel wireless pressure sensor system that can monitor and report real-time changes in pressure on the rotor blade of a low speed axial compressor is demonstrated. The pressure sensor was positioned on the second-stage rotor at approximately the mid-span location on the pressure surface of the blade near the leading edge and hard wired to a circuit box located on the center line of the compressor drum. The output of the pressure sensor is converted from a voltage to a frequency and transmitted wirelessly via circularly polarized antenna to a stationary antenna that was approximately 1 meter away, mounted at the centerline location on the inlet cart. The output signal was recorded on a spectrum analyzer with a LabVIEW program for data acquisition. Compressor rotation was ramped from 0 RPM up to its design speed of 1000 RPM and the airflow was decreased by closure of downstream throttle valve until the compressor stalled. The measurements from the wireless pressure system show increasing pressure as compressor flow rate is decreased, until a precipitous drop in pressure occurs which signals that the compressor has stalled.