An evaluation of steam turbine exhaust hood performance using a water flow testing facility
This thesis describes an experimental program which incorporated the design, fabrication and testing of a water flow facility for a 1:44 scale model of a Westinghouse turbine exhaust hood. The objective of this program was to evaluate the ability of the water flow facility to compare exhaust hood performance with different flow guide geometries. Validation of the facility was judged by comparing the results with those from similar air flow tests, which are considered indicative of actual steam system performance. The water flow tests were conducted at low Mach numbers, whereas the air flow tests were conducted at high subsonic Mach numbers. Consequently, comparisons were made with air data extrapolated to low Mach numbers. To correlate data between air and water systems, a similitude analysis was performed over the spectrum of flow conditions. Both the water flow model (WFM) and the air flow model (AFM) were subjected to similar inlet conditions. Comparisons were made with available air data. These data included results from three flow guides (the "Original", "Optimized", and "44") subjected to increasing inlet total pressure gradients with zero or thirty degree swirl. In addition, air data were available for the Original flow guide geometry at zero degree swirl and constant, increasing and decreasing total pressure gradients. Other inlet combinations were also tested for all flow guides, despite the inavailability of analogous air data, and these results are summarized in Appendix G. The WFM was instrumented similarly to the AFM so that a comparison could be made. The key parameter for comparison is the static pressure recovery coefficient (Cp), which was calculated from system pressure readings. Comparison of the WFM with the AFM data yielded the following conclusions: 1) Flow guide performance trends from air tests (extrapolated to low or near zero Mach number) could be qualitatively reproduced with the water flow facility. Quantitative comparisons, however, were not possible. 2) The pressure recovery behavior obtained from water tests is highly sensitive to the gradient of the total radial pressure profile. Small changes in the pressure profile could result in significant changes in the pressure coefficient. The effects of the gradient variations are not consistent, however, from one flow guide to another. For example, a small change in the pressure gradient could result in an increase in the Cp for one flow guide. In contrast, the same change in the pressure gradient could give rise to a decrease in Cp for another flow guide. Thus, specific effects due to changes in the inlet pressure gradient could not be isolated.
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Master of Science (M.S.)
College of Engineering
Mechanical Engineering and Aerospace Sciences
Length of Campus-only Access
Masters Thesis (Open Access)
Dissertations, Academic -- Engineering; Engineering -- Dissertations, Academic
Scarbrough, Dana, "An evaluation of steam turbine exhaust hood performance using a water flow testing facility" (1990). Retrospective Theses and Dissertations. 4076.