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  • 1975-1979  (7)
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Year
  • 1
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    Boundary layer bleed system study for a full-scale, mixed-compression inlet with 45 percent internal contraction (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The results of an experimental bleed development study for a full-scale, Mach 2.5, axisymmetric, mixed-compression inlet were presented. The inlet was designed to satisfy the airflow requirements of the TF30-P-3 turbofan engine. Capabilities for porous bleed on the cowl surface and ram-scoop/flush-slot bleed on the centerbody were provided. A configuration with no bleed on the cowl achieved a minimum stable, diffuser exit, total pressure recovery of 0.894 with a centerbody-bleed mass flow ratio of 0.02. Configurations with cowl bleed had minimum stable recoveries as high as 0.900 but suffered range decrement penalties from the increased bleed mass flow removal. Limited inlet stability and unstart angle-of-attack data are presented.
    Keywords: AERODYNAMICS
    Type: NASA-TM-X-3358 , E-8494
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    An Experimental Investigation of Forced Mixing of a Turbulent Boundary Layer in an Annular Diffuser (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The forced mixing process of a turbulent boundary layer in an axisymmetric annular diffuser using conventional wing-like vortex generators was studied. Flow field measurements were made at four axial locations downstream of the vortex generators. At each axial location, a total of 25 equally spaced profiles were measured behind three consecutive vortex generators which formed two pairs of vortex generators. Hot film anemometry probes measured the boundary layer turbulence structure at the same locations where pressure measurements were made. Both single and cross film probes were used. The diffuser turbulence data was teken only for a nominal inlet Mach number of 0.3. Three vortex generator configurations were tested. The differences between configurations involved changes in size and relative vortex generator positions. All three vortex generator configurations tested provided increases in diffuser performance. Distinct differences in the boundary layer integral properties and skin friction levels were noted between configurations. The axial turbulence intensity and Reynolds stress profiles measured displayed similarities in trends but differences in levels for the three configurations.
    Keywords: AERODYNAMICS
    Type: NASA-TM-79171 , E-9947
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Performance of vortex generators in a Mach 2.5 low-bleed full scale 45-percent-internal-contraction axisymmetric inlet (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Steady-state and dynamic flow characteristics associated with two sets of vortex generators having different mixing criteria were determined. The inlet performance with and without these vortex generators is presented. The vortex generators were successful in eliminating separation, increasing area-weighted total pressure recovery, and decreasing distortion. Transmission times obtained from cross-correlations of the wall static pressures and the diffuser exit total pressure showed no effect of the upstream flow characteristics on the diffuser exit pressures when generators were used. Without generators, separation occurred and the upstream pressure characteristics had immediate effects on the diffuser exit pressure characteristics.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3195 , E-8117
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 4
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    VSTOL tilt nacelle aerodynamics and its relation to fan blade stresses (1978)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A scale model of a VSTOL tilt nacelle with a 0.508 m single stage fan was tested in the NASA Lewis 9x15 Low Speed Wind Tunnel to ascertain inlet aerodynamic and fan aeromechanical performance over the low speed flight envelope. Fan blade stress maxima occurred at discrete rotational speeds corresponding to integral engine order vibrations of the first flatwise bending mode. Increased fan blade stress levels coincided with internal boundary layer separation occurring but became severe only when the separation location had progressed to the entry lip region of the inlet. The inlet/fan system could operate within the low speed flight envelope without incurring fan blade stress limits although boundary layer separation did occur for certain operating conditions.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 78-958 , Joint Propulsion Conference; Jul 25, 1978 - Jul 27, 1978; Las Vegas, NV; US
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    VSTOL tilt nacelle aerodynamics and its relation to fan blade stresses (1978)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: A scale model of a VSTOL tilt nacelle with a 0.508 m single stage fan was tested in a low speed wind tunnel to ascertain inlet aerodynamic and fan aeromechanical performance over the low speed flight envelope. Fan blade stress maxima occurred at discrete rotational speeds corresponding to integral engine order vibrations of the first flatwise bending mode. Increased fan blade stress levels coincided with internal boundary layer separation but became severe only when the separation location had progressed to the entry lip region of the inlet.
    Keywords: AERODYNAMICS
    Type: NASA-TM-78899 , E-9635 , Joint Propulsion Conf.; Jul 25, 1978 - Jul 27, 1978; Las Vegas, NV; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Design of a very-low-bleed Mach 2.5 mixed-compression inlet with 45 percent internal contraction (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A full-scale, mixed-compression inlet was designed for operation with the TF30-P-3 turbofan engine and tested at Mach numbers of 2.5 and 2.0. The two-cone axisymmetric inlet had minimum internal contraction consistent with high total pressure recovery and low cowl drag. At Mach 2.5, inlet recovery was 0.906 with only 0.021 centerbody bleed mass-flow ratio and no cowl bleed. Increased centerbody bleed gave a maximum inlet unstart angle of attack of 6.85 deg. At Mach 2.0, inlet recovery was 0.94 with only 0.014 centerbody bleed mass-flow ratio and no cowl bleed. Inlet performance and angle-of-attack tolerance is presented for operation at Mach numbers of 2.5 and 2.0.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-TM-X-3135 , E-8098
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 7
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    Operating characteristics of an inlet model tested with a 0.5m powered fan at high angles of attack (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An inlet model designed for high angle of attack capability, coupled to a .508 m tip diameter turbofan simulator, was tested in the NASA-Lewis Research Center's 9-by 15-ft low speed wind tunnel. The test variables were: tunnel velocity, 0 to 75 m/s; inlet angle of attack, 0 to 120 deg; and fan face corrected airflow per unit area, 75 to 200 kg/s sqm. The inlet flow separation boundaries, the fan face total pressure recovery and distortion characteristics, and the fan blade vibratory stresses were determined. The recovery, distortion, and stress levels showed no abrupt changes at the onset of separation, but became gradually more unfavorable as the size and intensity of the separation increased as induced by increasingly severe operating conditions. Performance characteristics for a large scale model of the inlet were estimated from these test results.
    Keywords: AERODYNAMICS
    Type: NASA-CR-135270 , D180-20798-1
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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