Miniature fiber optic pressure sensor for turbomachinery applications

Development of pressure sensors for the instrumentation of experimental aer odynamic facilities has traditionally concentrated on electrical techniques . An improvement in the currently attainable temporal and spatial resolutio n in pressure measurement would be beneficial in the characterization of tu rbulent flows behind turbine rotor stages, for example. We present results obtained in a turbine test rig from a fiber optic pressure sensor based upo n the interferometric response of an extrinsic cavity formed between the in terrogation fiber and a reflective diaphragm. We discuss the design trade o ffs, optical interrogation and temperature sensitivity of such a configurat ion, and demonstrate the success of the design in small-scale shock tube ex periments. We then describe the application of the sensor in a full scale t urbine test facility in which pressure signals with frequency components ex ceeding 200 kHz were obtained. (C) 1999 American Institute of Physics. [S00 34-6748(99)00903-X].