Miniature fiber optic pressure sensor for turbomachinery applications

Abstract

Development of pressure sensors for the instrumentation of experimental aerodynamic facilities has traditionally concentrated on electrical techniques. An improvement in the currently attainable temporal and spatial resolution in pressure measurement would be beneficial in the characterization of turbulent flows behind turbine rotor stages, for example. We present results obtained in a turbine test rig from a fiber optic pressure sensor based upon the interferometric response of an extrinsic cavity formed between the interrogation fiber and a reflective diaphragm. We discuss the design trade offs, optical interrogation and temperature sensitivity of such a configuration, and demonstrate the success of the design in small-scale shock tube experiments. We then describe the application of the sensor in a full scale turbine test facility in which pressure signals with frequency components exceeding 200 kHz were obtained.