Tests have been conducted with a series of cttffuser shapes defined by empirical equations having constants which are relate* *o the initial boundary-layer thickness. The shapes were designed to provide high pres¬sure recovery at near sonic inlet Mach numbers, and tests were conducted through the mass-flow range with a variety of attached and separated initial boundary layers. Tests were also conducted with two offset duct3 and with a variety of surface conditions in the shortest duct.nThe experimental results provide substantiation for the design trends upon which the empirical equations were based. In addition, it was found that for the axially symmetric ducts tested, the effect of initial boundary-layer thickness on pressure recovery was as important as that of duct shape. The best performance was obtained with a short duct with a thin initial boundary layer. With separated boundary layers, extended entry lengths provided markedly improved pressure recovery and flow steadiness relative to a similar duct with no entry extension. The off-set ducts suffered losses in all performance parameters relative to a similar axially symmetric duct. Near maximum mass flow, the surface con-ditions investigated had only small adverse effects on pressure recovery. A loss of several percent in total pressure recovery occurred with air leakage into the duct near the throat.
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