An analytical and experimental study was conducted to investigate the effects of concurrent changes in curvature and cross-sectional areas on flow in a two-dimensioanl, S-shaped duct. A computer code based on the inverse method for the design of two-dimensional ducts was developed and has been supplemented by a boundary layer analysis code. Numerical experiments were performed by generating ducts of varying geometries and selecting the one providing an approximately optimal duct for a given offset-to-length ratio. The criteria for optimization were to achieve maximum pressure recovery and yet to avoid flow separation. After several numerical experiments, a 1:2 pressure ratio, S-shaped diffuser geometry was selected, and a physical model was built and tested. using a Laser-Doppler Velocimeter and a multiport, pressure-measuring Scanivalve system, static pressure, velocity, and turbulence measurements were obtained for flow in the model duct at three different Reynolds numbers. The experimental results closely match the theoretical predictions. This study provides results and conclusions which should be of interest to scientists and engineers involved with the fluid mechanics of internal flows and particularly with the flow in helicopter and fixed-wing aircraft engine inlet ducts.
Turbulent incompressible air flow through S-shaped ducts with cross-sectional area change
Turbulente inkompressible Luftstroemung durch S-foermige Leitungen mit Aenderung der Querschnittsflaeche
Forum on Turbulent Flows 1989, The 3rd Joint ASCE/ASME Mechanics Conf. ; FED-76 , Jul ; 49-57
1989
9 Seiten, 11 Bilder, 11 Quellen
Conference paper
English
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