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  • 1
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    Experimental Investigation of Boundary Layer Behavior in a Simulated Low Pressure Turbine (1999)
    In:  CASI
    Details
    Publication Date: 2013-08-29
    Description: A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the y pressure distribution of an actual LPT blade onto a flat plate. The experiments were carried out at Reynolds numbers of 100,000 and 250,000 with three levels of freestream turbulence. The main emphasis in this paper is placed on flow field surveys performed at a y Reynolds number of 100,000 with levels of freestream turbulence ranging from 0.8% to 3%. Smoke-wire flow visualization data was used to confirm that the boundary layer was separated and formed a bubble. The transition process over the separated flow region is observed to be similar to a laminar free shear layer flow with the formation of a large coherent eddy structure. For each condition, the locations defining the separation bubble were determined by careful examination of pressure and mean velocity profile data. Transition onset location and length determined from intermittency profiles decrease as freestream turbulence levels increase. Additionally, the length and height of the laminar separation bubbles were observed to be inversely proportional to the levels of freestream turbulence.
    Keywords: Fluid Mechanics and Thermodynamics
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Detailed flow surveys of turning vanes designed for a 0.1-scale model of NASA Lewis Research Center's proposed altitude wind tunnel (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Detailed flow surveys downstream of the corner turning vanes and downstream of the fan inlet guide vanes have been obtained in a 0.1-scale model of the NASA Lewis Research Center's proposed Altitude Wind Tunnel. Two turning vane designs were evaluated in both corners 1 and 2 (the corners between the test section and the drive fan). Vane A was a controlled-diffusion airfoil and vane B was a circular-arc airfoil. At given flows the turning vane wakes were surveyed to determine the vane pressure losses. For both corners the vane A turning vane configuration gave lower losses than the vane B configuration in the regions where the flow regime should be representative of two-dimensional flow. For both vane sets the vane loss coefficient increased rapidly near the walls.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TP-2680 , E-3294 , NAS 1.60:2680
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Experimental evaluation of corner turning vanes (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two types of turning vane airfoils (a controlled-diffusion shape and a circular arc shape) have been evaluated in the high-speed and fan-drive corners of a 0.1-scale model of NASA Lewis Research Center's proposed Altitude Wind Tunnel. The high-speed corner was evaluated with and without a simulated engine exhaust removal scoop. The fan-drive corner was evaluated with and without the high-speed corner. Flow surveys of pressure and flow angle were taken for both the corners and the vanes to determine their respective losses. The two-dimensional vane losses were low; however, the overall corner losses were higher because three-dimensional flow was generated by the complex geometry resulting from the turning vanes intersecting the end wall. The three-dimensional effects were especially pronounced in the outer region of the circular corner.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TM-100143 , E-3695 , NAS 1.15:100143
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    NASA TECHNICAL REPORTS
  • 4
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    Experimental evaluation of two turning vane designs for fan drive corner of 0.1-scale model of NASA Lewis Research Center's proposed altitude wind tunnel (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two turning vane designs were experimentally evaluated for corner 2 of a 0.1 scale model of the NASA Lewis Research Center's proposed Altitude Wind Tunnel (AWT). Corner 2 contained a simulated shaft fairing for a fan drive system to be located downstream of the corner. The corner was tested with a bellmouth inlet followed by a 0.1 scale model of the crossleg diffuser designed to connect corners 1 and 2 of the AWT. Vane A was a controlled-diffusion airfoil shape; vane B was a circular-arc airfoil shape. The A vanes were tested in several arrangements which included the resetting of the vane angle by -5 degrees or the removal of the outer vane. The lowest total pressure loss for vane A configuration was obtained at the negative reset angle. The loss coefficient increased slightly with the Mach number, ranging from 0.165 to 0.175 with a loss coefficient of 0.170 at the inlet design Mach number of 0.24. Removal of the outer vane did not alter the loss. Vane B loss coefficients were essentially the same as those for the reset vane A configurations. The crossleg diffuser loss coefficient was 0.018 at the inlet design Mach number of 0.33.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TP-2646 , E-3175 , NAS 1.60:2646
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    NASA TECHNICAL REPORTS
  • 5
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    Low Pressure Turbine Flow Physics Program (1997)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: As part of the collaborative NASA/industry/academia Low Pressure Turbine (LPT) Flow Physics program, smoke flow was visualized from a simulated low-pressure turbine experiment in NASA Lewis Research Center's CW-7 test facility. As shown in the photographs, a laminar separation bubble formed on the bottom flat surface. This is characteristic of the flows in a large-scale, low-pressure turbine operating under off-design conditions. A contoured upper wall was designed to generate a pressure distribution on a flat plate to match the suction surface pressure distribution from a generic low-pressure turbine blade.
    Keywords: Research and Support Facilities (Air)
    Type: Research and Technology 1996; NASA-TM-107350
    Format: text
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    NASA TECHNICAL REPORTS
  • 6
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    Supersonic investigation of two dimensional hypersonic exhaust nozzles (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An experimental investigation was conducted in the NASA Lewis 10 x 10 ft supersonic Wind Tunnel to determine the performance characteristics of 2D hypersonic exhaust nozzles/afterbodies at low supersonic conditions. Generally, this type of application requires a single expansion ramp nozzle (SERN) that is highly integrated with the airframe of the hypersonic vehicle. At design conditions (hypersonic speeds), the nozzle generally exhibits acceptable performance. At off-design conditions (transonic to mid-supersonic speeds), nozzle performance of a fixed geometry configuration is generally poor. Various 2-D nozzle configurations were tested at off-design conditions from Mach 2.0 to 3.5. Performance data is presented at nozzle pressure ratios from 1 to 35. Jet exhaust was simulated with high-pressure air. To study performance of different geometries, nozzle configurations were varied by interchanging the following model parts: internal upstream contour, expansion ramp, sidewalls, and cowl.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-105687 , E-7067 , NAS 1.15:105687
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Analysis and Optimization of Truncated Scarf Nozzles Subject to External Flow Conditions (1988)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Results of a calculation of an optimized truncated scarfed nozzle were compared. The truncated scarfed nozzle was designed for an exit Mach number of 6.0, i.e., the Mach number at the last nozzle characteristic is 6.0, with an external flow Mach number of 5.0. The nozzle was designed by the Rao method for optimum thrust nozzles modified for 2-D flow and truncated scarfed nozzle applications. This design was analyzed using a shock-fitting method for 2-D supersonic flows. Excellent agreement was achieved between the design and analysis. Truncation of the lower nozzle wall (cowl) revealed that there is an optimum length for truncating the cowl without degrading the nozzle performance. Truncation of the nozzle cowl past this optimal length should be analyzed in trade-off studies for thrust loss versus gross vehicle weight. Plots of the oblique shock wave equations were also identified which will allow computation of slip line angle, dynamic pressure coefficient, or ambient Mach number for various specific heat ratios.
    Keywords: AERODYNAMICS
    Type: NASA-TM-100955 , E-4146 , NAS 1.15:100955
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Experimental evaluation of corner vanes - Summary (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Two types of turning vane airfoils (a controlled-diffusion shape and a circular arc shape) have been evaluated in the high-speed and fan-drive corners of a 0.1-scale model of NASA Lewis Research Center's proposed Altitude Wind Tunnel. The high-speed corner was evaluated with and without a simulated engine exhaust removal scoop. The fan-drive corner was evaluated with and without the high-speed corner. Flow surveys of pressure and flow angle were taken for both the corners and the vanes to determine their respective losses. The two-dimensional vane losses were low; however, the overall corner losses were higher because three-dimensional flow was generated by the complex geometry resulting from the turning vanes intersecting the end wall. The three-dimensional effects were especially pronounced in the outer region of the circular corner.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: SAE PAPER 871784
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Analysis and design of optimized truncated scarfed nozzles subject to external flow effects (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Rao's method for computing optimum thrust nozzles is modified to study the effects of external flow on the performance of a class of exhaust nozzles. Members of this class are termed scarfed nozzles. These are two-dimensional, nonsymmetric nozzles with a flat lower wall. The lower wall (the cowl) is truncated in order to save weight. Results from a parametric investigation are presented to show the effects of the external flowfield on performance.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 90-2222
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    Experimental Evaluation of Turning Vane Designs for High-speed and Coupled Fan-drive Corners of 0.1-scale Model of NASA Lewis Research Center's Proposed Altitude Wind Tunnel (1987)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Two turning vane designs were experimentally evaluated for the fan-drive corner (corner 2) coupled to an upstream diffuser and the high-speed corner (corner 1) of the 0.1 scale model of NASA Lewis Research Center's proposed Altitude Wind Tunnel. For corner 2 both a controlled-diffusion vane design (vane A4) and a circular-arc vane design (vane B) were studied. The corner 2 total pressure loss coefficient was about 0.12 with either vane design. This was about 25 percent less loss than when corner 2 was tested alone. Although the vane A4 design has the advantage of 20 percent fewer vanes than the vane B design, its vane shape is more complex. The effects of simulated inlet flow distortion on the overall losses for corner 1 or 2 were small.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-TP-2681 , E-3218 , NAS 1.60:2681
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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