An Experimental Investigation of the Flow Through the Aft Portion of a High-Flow Nacelle Bypass Concept
50th AIAA Aerospace Sciences Meeting including the New Horizons Forum and Aerospace Exposition AIAA 2012-0872 09 - 12 January 2012, Nashville, Tennessee An Experimental Investigation of the Flow Through the Aft Portion of a High-Flow Nacelle Bypass Concept Ruben Hortensius1, Gregory S. Elliott2, and Michael B. Bragg3 University of Illinois at Urbana-Champaign, Urbana, IL, 61801 In order to minimize sonic boom contribution, a conventional turbofan propulsion system was shape tailored to circularize its non-axisymmetric external profile, which, after the addition of a new supersonic inlet and nozzle, has led to a new supersonic propulsion system. A new, secondary, bypass with a highly complex internal geometry was created during this process. The high-flow nacelle bypass geometry includes a forward and aft fairing to direct the flow around the gearbox, a set of thin forward guide vanes, and a set of thick aft guide vanes. The aft guide vanes, which also serve structural purposes, are used to direct the flow such that the exhaust is a uniform, nearly-full annular cross-section, and to choke and then accelerate the flow to supersonic freestream conditions upon exit. A supersonic wind tunnel facility at the University of Illinois was modified and used to simulate the flow through the aft bypass at approximately 6% scale. Two models, one with and one without guide vanes, are studied. Due to facility limitations, the design operating condition could not be achieved; a series of off-design operating conditions are tested instead. Radial pressure surveys are conducted at five azimuthal stations at the inlet to the aft bypass in order to establish in-flow conditions.
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