Non-Axisymmetric Infrared Plume Tomography for Rocket Plume Species and Temperature Distributions

Spatial uniformity within combustion devices, especially circumferential, is extremely important to the reliability and durability of a liquid rocket engine. Conventional combustion diagnostics, e.g. pressure and thrust, characterize global engine behavior, but provide no direct information about thermal and species distributions across the engine. Sierra Engineering has shown that exhaust plume measurements can provide many of these details with sensitivity much greater than conventional diagnostics. We have developed a turn-key infrared emission-absorption spectroscopy system capable of planar measurements across a rocket exhaust plume. Data reduction from this single spectrometer system requires that the flow field be assumed axisymmetric. However, simultaneous measurements from three spectrometers allow complete resolution of non-axisymmetric flow fields. The necessary tomographic data reconstruction techniques are commonly employed in the medical field for CAT-scan analyses. The subject proposal adapts the current Sierra emission-absorption plume diagnostic to a compact fiber-optic system suitable for deployment under realistic rocket test situations. The fiber-optic system enables the integration of three sensor systems into a single test setup, thereby permitting accurate characterization of non-axisymmetric flow fields.