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  • 1
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    Core compressor exit stage study, 2 (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A total of two three-stage compressors were designed and tested to determine the effects of aspect ratio on compressor performance. The first compressor was designed with an aspect ratio of 0.81; the other, with an aspect ratio of 1.22. Both compressors had a hub-tip ratio of 0.915, representative of the rear stages of a core compressor, and both were designed to achieve a 15.0% surge margin at design pressure ratios of 1.357 and 1.324, respectively, at a mean wheel speed of 167 m/sec. At design speed the 0.81 aspect ratio compressor achieved a pressure ratio of 1.346 at a corrected flow of 4.28 kg/sec and an adiabatic efficiency of 86.1%. The 1.22 aspect ratio design achieved a pressure ratio of 1.314 at 4.35 kg/sec flow and 87.0% adiabatic efficiency. Surge margin to peak efficiency was 24.0% with the lower aspect ratio blading, compared with 12.4% with the higher aspect ratio blading.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159812 , PWA-5561-66
    Format: application/pdf
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  • 2
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    Core compressor exit stage study. 1: Aerodynamic and mechanical design (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The effect of aspect ratio on the performance of core compressor exit stages was demonstrated using two three stage, highly loaded, core compressors. Aspect ratio was identified as having a strong influence on compressors endwall loss. Both compressors simulated the last three stages of an advanced eight stage core compressor and were designed with the same 0.915 hub/tip ratio, 4.30 kg/sec (9.47 1bm/sec) inlet corrected flow, and 167 m/sec (547 ft/sec) corrected mean wheel speed. The first compressor had an aspect ratio of 0.81 and an overall pressure ratio of 1.357 at a design adiabatic efficiency of 88.3% with an average diffusion factor or 0.529. The aspect ratio of the second compressor was 1.22 with an overall pressure ratio of 1.324 at a design adiabatic efficiency of 88.7% with an average diffusion factor of 0.491.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-159714 , PWA-5561-55
    Format: application/pdf
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  • 3
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    High-loading low-speed fan study. 4: Data and performance with redesign stator and including a rotor tip casing treatment (1972)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A single stage fan with a rotor tip speed of 1000 ft/sec(304.8 m/sec) and a hub-to-tip ratio of 0.392 was retested with a redesigned stator. Tests were conducted with uniform inlet, tip-radial, hub-radial, and circumferential inlet distortions. With uniform inlet flow, stall margin was improved 12 percentage points above that with the original stator. The fan demonstrated an efficiency of 0.883 and a stall margin of 15 percent at a pressure ratio of 1.488 and a specific flow of 41.17 lb/sec/sq ft. Tests were also made with a redesigned casing treatment consisting of skewed slots over the rotor blade tips. This casing treatment gave a 7 percentage point improvement in stall margin when tested with tip radial distortion (when the rotor tip initiated stall). Noise measurements at the fan inlet and exit indicate no effect from closing the stator 10 degrees, nor were there measurable effects from adding skewed slots over the blade tips.
    Keywords: FLUID MECHANICS
    Type: NASA-CR-120866 , PWA-4326
    Format: application/pdf
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  • 4
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    High loading, low speed fan study, 5 (1973)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A low speed, low noise, single stage fan was designed and tested. Design pressure ratio was 1.5 at a rotor tip speed of 1000 ft/sec. No inlet guide vane was used, the rotor stator was spaced and the number of rotor and stator airfoils was selected for low noise. Tests were conducted with uniform and distorted inlet flows. Stall margin of the initial design was too low for practical application. Airfoil slots and boundary layer and endwall devices did not improve stall margin sufficiently. A redesigned stator with reduced loadings increased stall margin, giving a fan efficiency of 0.883, 15% stall margin, and a 1.474 pressure radio at a specific flow of 41.7 lb/sec sq ft. Casing treatment over rotor tips improved stall margin with distorted inlet flow; vortex generators did not. Blade passing frequency noise increased with rotor relative Mach number. No supersonic fan noise was measured below 105% of design speed. Slotting airfoils, casing treatments, and a reduction of the ratio (number-stators/number-rotors) from (2n + 16) to (2n + 2) had no significant effects on noise.
    Keywords: AIRCRAFT
    Type: NASA-CR-121148 , PWA-4517
    Format: application/pdf
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  • 5
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    Results of acoustic testing of the JT8D-109 refan engines (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: A JT8D engine was modified to reduce jet noise levels by 6-8 PNdB at takeoff power without increasing fan generated noise levels. Designated the JT8D-109, the modified engines featured a larger single stage fan, and acoustic treatment in the fan discharge ducts. Noise levels were measured on an outdoor test facility for eight engine/acoustic treatment configurations. Compared to the baseline JT8D, the fully treated JT8D-109 showed reductions of 6 PNdB at takeoff, and 11 PNdB at a typical approach power setting.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: NASA-CR-134875 , PWA-5298
    Format: application/pdf
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  • 6
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    High-loading low-speed fan study. 3 - Data and performance slotted blades and vanes and rotor tip treatment (1971)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Slotted blades and vanes and rotor tip design for highly loaded, low speed fan stage applicable to low noise aircraft engines
    Keywords: PROPULSION SYSTEMS
    Type: NASA-CR-72895 , PWA-3899
    Format: application/pdf
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  • 7
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    High-loading low-speed fan study. Part 2 - data and performance unslotted blades and vanes (1969)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Aerodynamic performance, and noise measurements of highly loaded low speed fan
    Keywords: AERODYNAMICS
    Type: NASA-CR-72667 , PWA-3653
    Format: application/pdf
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