An experimental investigation of the effects of nozzle operating conditions on the development of nozzle-exit boundary layers of highly heated air free jets is reported in this paper. The total pressure measurements in the nozzle-exit boundary layer were obtained at a range of jet Mach numbers from 0.1 to 0.97 and jet total temperatures up to 900 K. The analysis of results shows that the nozzle-exit laminar boundary-layer development depends only on the nozzle-exit Reynolds number. For the nozzle-exit turbulent boundary layer, however, it appears that the effects of the jet total temperature on the boundary-layer integral characteristics are independent from the effect of the nozzle-exit Reynolds number. This surprizing finding has not yet been reported. Further, laminar boundary-layer profiles were compared with the Pohlhausen solution for a flat-wall converging channel and an acceptable agreement was found only for low Reynolds numbers. For turbulent boundary layers, the dependence of the shape factor on relative Mach numbers at a distance of one momentum thickness from the nozzle wall resembles Spence’s prediction. Finally, the calculated total pressure loss coefficient was found to depend on the nozzle-exit Reynolds number for the laminar nozzle-exit boundary layer, while for the turbulent exit boundary layer this coefficient appears to be constant.
- International Gas Turbine Institute
An Experimental Investigation of Nozzle-Exit Boundary Layers of Highly Heated Free Jets
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Lepicovsky, J. "An Experimental Investigation of Nozzle-Exit Boundary Layers of Highly Heated Free Jets." Proceedings of the ASME 1990 International Gas Turbine and Aeroengine Congress and Exposition. Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration. Brussels, Belgium. June 11–14, 1990. V004T09A030. ASME. https://doi.org/10.1115/90-GT-255
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