INVESTIGATION OF MHD FLOW STRUCTURE AND FLUCTUATIONS BY POTASSIUM LINESHAPE FITTING

Multiple Potassium D-line emission-absorption spectra from a high-temperature, coal-fired magnetohydrodynamic (MHD) flow have been fit to a radiative transfer, boundary layer flow model. The results provide information about the thickness and shape of the thermal boundary layer and the bulk potassium seed atom density in a simulated MHD channel flow. Sample distributions for an entire set of more than 6000 spectra clearly indicate the typical values and magnitude of fluctuations for the flow core temperature, near wall temperature, boundary layer width, and potassium seed atom density. Sample distributions for selected times during the 8 h of measurements indicate periods of unstable combustion. In addition, broadband particle parameters during the unstable start of the test may be related to differing particle and gas temperatures. The results clearly demonstrate the ability of lineshape fitting to provide valuable data for diagnosing the high-speed turbulent flow.