Measurements of temperature and seed atom density in high-speed MHD flows

Abstract

Emission absorption measurements of temperature, potassium seed atom density, and electron conductivity have been demonstrated in the high-speed, turbulent coal-fired flow of a simulated MHD channel. A two-beam optical system provides coincident exposures of transmitted lamp and emission-only signals with a time resolution of one-half ms. Multiwavelength detection allows for optimization of the measurement wavelengths for a twowavelength analysis that eliminates error due to ash/slag particle extinction and emission. Previous measurements with single beam, 1 ms temporally separated measurements showed large standard deviations due to fluctuations in flow parameters between the two noncoincident exposures. Comparison of the two types of measurements for nominally the same flow conditions reveals the considerable improvement in measurement uncertainty with the two-beam optical system.