Automated Design Optimization of a Three-Dimensional Subsonic Diffuser

作者：Aranake Aniket^*; Lee Jin Gyu; Knight Doyle; Cummings Russell M; Cox John; Paul Micah; Byerley Aaron R

来源：Journal of Propulsion and Power, 2011, 27(4): 838-846.

DOI：10.2514/1.50522

An automated computational design optimization of a doubly offset (serpentine) subsonic diffuser is performed to assess the validity of a simple design principle for reducing flowfield distortion at the outlet. The design principle specifies that the flow be overexpanded within the bend, i.e., that the cross-sectional area in the bend exceed the cross-sectional area at the outlet. A baseline diffuser is defined as a monotonically increasing circular cross section following the specified doubly offset centerline. The design optimization uses a circular inlet and outlet that are identical to the baseline design, but permits a smooth blending of the cross section from circular to elliptical at the midpoint of the bend and returning to circular at the outlet while following the specified doubly offset centerline of the baseline design. The design variables of this study are the semimajor and semiminor axes of the ellipse at the midpoint. A commercial CAD program is used to loft the cross section smoothly from inlet to outlet. Turbulence is incorporated using a two-equation turbulence model. The automated computational design indicates that a substantial reduction in distortion is achieved by overexpanding the flow within the bend. Experimental evaluation of the baseline and optimal designs confirm an approximate 50% reduction in distortion coefficient for the optimal design compared with the baseline configuration, although the absolute values of the computed and experimental distortion coefficients differ.

• 出版日期2011-8