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  • 1990-1994  (8)
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  • 1
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    Experimental investigation of turbulent flow through a circular-to-rectangular transition duct (1990)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duct was studied experimentally. The cross-sectional geometry all along the duct was defined using the equation of a superellipse. The three mean velocity components and the six Reynolds stress components were measured at two axial stations downstream from the transition. It is shown that a secondary flow vortex pair which develops along the duct sidewalls significantly distorts the mean and turbulence fields. At the duct exit, the flow is not in local equilibrium, but recovers to local equilibrium conditions in the rectangular extension duct. Analysis demonstrates that conventional wall functions are not applicable at all streamwise locations in the duct.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-1505
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  • 2
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    Experimental investigation of flow about a strut-endwall configuration (1990)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: An experimental study was conducted to investigate incompressible flow about a strut-endwall configuration positioned within a constant area duct. The endwal boundary layer was tripped, but natural transition occurred on the strut surface. The results indicate that spanwise varying transition on this surface leads to the formation of a secondary vortex which coexists with the horseshoe vortex generated by endwall flow separation upstream of the strut leading edge. Both vortices are similar in strength downstream of the strut trailing edge, and both distort the primary flow and local turbulence structure in the wake-endwall region. The level of distortion is demonstrated by means of axial mean velocity contours, turbulence kinetic energy contours, and Reynolds shear stress contours measured in the cross plane at two streamwise locations. Analysis of the results shows that conventional eddy viscosity and k-epsilon transport equation models are not wholly adequate for predicting this flow situation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-1541
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  • 3
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    Design and operation of a supersonic annular flow facility (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Supersonic annular flow passages exist in propulsion applications that include dual combustion ramjet engines where a supersonic annular flow (the outer flow) mixes with a sonic (or supersonic) gas generator flow (the inner flow) in the shock expansion zone downstream of the gas generator nozzle exit. Other engine designs include components in the form of annular ducts whose cross-sectional area varies in the streamwise flow direction. In some of these configurations, it is necessary to support the outer shroud (cowl) by means of struts positioned between the cowl and centerbody. To investigate the distorting influence of these struts on the local flow structure, it is first necessary to ensure that the intrinsic flow without struts is free of wave reflections and the effects of upstream disturbances. It is also necessary to demonstrate that the intrinsic flow exhibits the characteristics of a well-defined turbulent boundary layer flow, so that changes in the local flow structure induced by the presence of struts can be interpreted properly. The purpose of this Note is to demonstrate that a supersonic flow facility that meets these objectives has been developed.
    Keywords: AERODYNAMICS
    Type: AIAA Journal (ISSN 0001-1452); 32; 7; p. 1528-1531
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  • 4
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    Experimental investigation of turbulent flow through a circular-to-rectangular transition duct (1992)
    In:  Other Sources
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    Publication Date: 2019-07-12
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 30; 367-375
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  • 5
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    Experimental investigation of flow about a strut-endwall configuration (1991)
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    Publication Date: 2019-07-12
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal (ISSN 0001-1452); 29; 2105-211
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  • 6
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    Investigation of a strut/endwall interaction in supersonic annular flow (1993)
    In:  Other Sources
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    Publication Date: 2019-08-27
    Description: A combined experimental and numerical investigation of strut/endwall interactions within an annular duct having a supersonic core flow has been conducted. Four diamond-shaped struts with a 7 deg half angle were positioned circumferentially equidistant within an annular duct having a gap height of 0.7 strut chords, and an inner-to-outer wall radius ratio of 0.7. Turbulent boundary layers exist on both inner and outer walls of the duct, but have not merged. The core flow upstream of the struts is uniform at a nominal Mach number of 3.0 and a Reynolds number of 3 x 10 exp 5 based on the strut chord length. Experimental results, which include Pitot pressure distributions within the flow field, static pressure distributions on the inner and outer walls of the duct, and oil flow visualization on the centerbody and strut, are presented and compared with CFD predictions. Secondary flows associated with the interactions are examined including the trajectories of the horseshoe vortices formed at the leading and trailing edges of the strut and the trajectories of the vortices formed in the corner of the strut/endwall intersection.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 93-1925 , ; 15 p.|AIAA, SAE, ASME, and ASEE, Joint Propulsion Conference and Exhibit; Jun 28, 1993 - Jun 30, 1993; Monterey, CA; United States
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  • 7
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    Experimental and numerical investigation of supersonic turbulent flow in an annular duct (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: Experimental and numerical results are presented for developing supersonic turbulent flow in an annular duct formed by a circular centerbody and outer shroud. The experimental results are based on data taken in a new flow facility that was designed to generate a shock-free, supersonic annular flow. Numerical computations were performed using the Baldwin-Lomax turbulence model for comparison with experimentally measured profiles. The results demonstrate that computed and measured profiles are in excellent agreement, so that studies can now be conducted of shock wave/boundary layer interaction phenomena within the duct, such as those induced by changes in downstream duct geometry or by the placement of struts between the duct walls.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 93-3123 , AIAA, Fluid Dynamics Conference; Jul 06, 1993 - Jul 09, 1993; Orlando, FL; United States|; 8 p.
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  • 8
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    A numerical investigation of supersonic strut/endwall interactions in annular flow with varying strut thickness (1993)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: A full 3D Navier-Stokes numerical investigation has been conducted of the shock-wave/boundary-layer flow interactions caused by four diamond-shaped struts, of varying thickness, in an annular duct with Mach 3 core flow and turbulent boundary-layers on both walls. Secondary flows caused by weak-to-strong interactions are examined in the vicinity of a strut which is bounded by curved endwalls. The duct endwall boundary-layer separated for the strongest interaction. The struts studied had maximum thickness-to-chord ratios of 0.125, 0.188, 0.250, and 0.500. The duct gap height is 0.7 strut chords, the duct inner-to-outer wall radius ratio is 0.7, and the Reynolds number is 3 x 10 exp 5 based on the strut chord length which was held constant for all interactions considered. The effects of strut thickness on the secondary flows are discussed, including: trajectories for the leading and trailing edge horseshoe vortices, strut/endwall corner vortices, and boundary-layer separation. The line of coalescence discussed in the literature, previously ascribed to boundary-layer separation, is shown to be caused by the leading edge horseshoe vortex convecting along the shock front.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 93-2927 , AIAA, Fluid Dynamics Conference; Jul 06, 1993 - Jul 09, 1993; Orlando, FL; United States|; 12 p.
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