A Miniature, High Temperature, High Frequency Fiber Optic Pressure Sensor for Scramjet Flow Characterization

Abstract

A miniature high temperature, high frequency, fiber optic pressure sensor capable of operation above 1000K and frequencies above 1MHz has been developed and tested. The sensor accuracy, pressure resolution, temporal resolution and high temperature capability were first demonstrated through a series of laboratory experiments. The sensors were then tested on the forebody and inside the combustor of a full-scale X-51 configuration at fully duplicated flight conditions in the LENS II reflected shock tunnel at the CUBRC facility in Buffalo, NY. The pressure sensors displayed good run-torun repeatability and durability during the 10 run test program. Forebody and tar combustor pressure measurements respectively displayed a ω -0.8 and ω -1 decay in the power spectrum for frequencies related to fluctuations within the log layer. At low frequency, the spectra were essentially flat. In the combustor, a significant increase in the power-law decay was observed for combusting runs. On the forebody, good spectral agreement was obtained at moderate frequencies between the fiber optic and Kulite piezoresistive pressure sensors. This sensing technology enables improved measurement capabilities during ground testing where high frequency pressure measurements in high temperature high speed flows are required.