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Show PAPER NO.5 Spatial Structure of a Confined Swirling Flow Using Planar Elastic Scattering and Laser Doppler Velocimetry· ABSTRACT c. F. Edward!: N. R. Fornaciari, C. M. Dunsky, K. D. Marx and W. T. Ashurst Combustion Research F aciIity Sandia National Laboratories Livermore, CA 94551-0969 This paper reports the results of a study of the instantaneous spatial structure of a confined swirling flow after a sudden expansion. The flow chosen corresponds to the cold flow conditions of an axisymmetric laboratory-scale research furnace. The swirl number of the flow is 0.7 at the inlet plane and the expansion diameter ratio is 6:1. The flow has a center hub-tothroat diameter ratio of 1 :4. Data are reported for the instantaneous spatial structure of the flow via transient planar elastic scattering imaging. This technique allows for unambiguous visualization of the spatial structure of the flow by slicing through it with a thin sheet (-1.5 mm) of light at various locations in the axial/radial and radial/azimuthal planes. By varying the time delay between introduction of the seeding material and data acquisition, features of the flow that would ordinarily be inaccessible are revealed. Laser Doppler velocimetry is used to measure the timeaveraged and RMS velocity components in all three coordinate directions. U sing this data, we construct a model of the flow from the viewpoint of the vorticity fed into the flow and its subsequent dynamics. This viewpoint suggests different reasons for the development of the observclble features of the flow and shows promise for helping to deconvolve the apparent complexity of this flowfield. INTRODUCTION Swirling flows are used in a wide variety of industrial processes and equipment in order to obtain high mixing rates and well-controlled operation. Yet despite a significant amount of research effort over the last 30 years, many of these flows remain elusive of efforts to predict ~ Pi<tS~ ... JTEI( ·Work perfonned at the Combustion Research Facility, Sandia National Laboratories, supported by the U.S. Department of Energy, Office of Industrial Processes, Advanced Industrial Concepts Division, and the Office of Basic Energy Sciences, Division of Chemical Sciences. - 1 - |
