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  • 1
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    Buffeting tests in a cryogenic windtunnel (1995)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Measurements of wing buffeting, using root strain gages, were made in the NASA Langley 0.3 m cryogenic wind tunnel to refine techniques which will be used in larger cryogenic facilities such as the United States National Transonic Facility (NTF) and the European Transonic Wind Tunnel (ETW). The questions addressed included the relative importance variations in frequency parameter and Reynolds number, the choice of model material (considering both stiffness and damping) and the effects of static aeroelastic distortion. The main series of tests was made on three half models of slender 65 deg delta wings with a sharp leading edge. The three delta wings had the same planform but widely differing bending stiffnesses and frequencies (obtained by varying both the material and the thickness of the wings). It was known that the steady flow on this configuration would be insensitive to variations in Reynolds number. On this wing at vortex breakdown the spectrum of the unsteady excitation is unusual, having a sharp peak at particular frequency parameter. Additional tests were made on one unswept half-wing of aspect ratio 1.5 with an NPL 9510 aerofoil section, known to be sensitive to variations in Reynolds number at transonic speeds. The test Mach numbers were M = 0.21 and 0.35 for the delta wings and to M = 0.30 for the unswept wing. On this wing the unsteady excitation spectrum is fairly flat (as on most wings). Hence correct representation of the frequency parameter is not particularly important.
    Keywords: AERODYNAMICS
    Type: Aeronautical Journal (ISSN 0001-9240); 99; 981; p. 1-14
    Format: text
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  • 2
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    Computer studies of hybrid slotted working sections with minimum steady interference at subsonic speeds (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Currently there is renewed interest in the evaluation and reduction of steady wind tunnel wall interference, especially for large models. Evaluation of previous predictions for perforated and slotted tunnels suggests that a hybrid slotted tunnel (i.e., a slotted tunnel with closed slats and perforated slots) should offer minimum corrections for upwash, flow curvature and solid blockage. This suggestion is confirmed by the present computer studies of a range of rectangular hybrid slotted tunnels. The computer studies are for tunnel working section height to breadth ratios of 0.835 and 0.600 over the Mach number range from 0 to 0.85. Wings swept at 28 deg and 50 deg, with ratios of model span to tunnel breadth varying from 0 to 0.7, are considered. An idealized fuselage shape is used to predict solid and wake blockage corrections for the wall configurations selected on the basis of minimum upwash and curvature interference.
    Keywords: AERODYNAMICS
    Type: Aeronautical Journal (ISSN 0001-9240); 89; 135-148
    Format: text
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  • 3
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    Calculation of transonic steady and oscillatory pressures on a low aspect ratio model and comparison with experiment (1985)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Pressure data measured by the British Royal Aircraft Establishment for the AGARD SMP tailplane are compared with results calculated using the transonic small perturbation code XTRAN3S. A brief description of the analysis is given and a recently developed finite difference grid is described. Results are presented for five steady and nine harmonically oscillating cases near zero angle of attack and for a range of subsonic and transonic Mach numbers.
    Keywords: AERODYNAMICS
    Format: text
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  • 4
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    Further buffeting tests in a cryogenic wind tunnel (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Further measurements of buffeting, using wing-root strain gauges, were made in the NASA Langley 0.3 m Cryogenic Wind Tunnel to refine techniques which will be used in larger cryogenic facilities such as the United States National Transonic Facility (NTF) and European Transonic Wind Tunnel (ETW). The questions addressed included the relative importance of variations in frequency parameter and Reynolds number, the choice of model material (considering both stiffness and damping) and the effects of static aeroelastic distortion. The main series of tests was made on half models of slender 65 deg delta wings with a sharp leading edge. The three delta wings had the same planform but widely different bending stiffness and frequencies (obtained by varying both the material and the thickness of the wings). It was known that the flow on this configuration would be insensitive to variations in Reynold number. Additional tests were made on one unswept half-wing of aspect ratio 1.5 with an NPL 9510 aerofoil section, known to be sensitive to variations in Reynolds number at transonic speeds. For brevity the test Mach numbers were restricted to M = 0.21 and 0.35 for the delta wings and to M = 0.30 for the unswept wing.
    Keywords: AERODYNAMICS
    Type: NASA-TM-107621 , NAS 1.15:107621 , RAE-TM-AERO-2231
    Format: application/pdf
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  • 5
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    Computer studies of hybrid-slotted working sections with minimum interference at subsonic speeds (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A series of computations on tunnel boundary-interference effects for hybrid-slotted working sections was performed using the WALINT code. The slots were modeled as lines of porosity with linear crossflow characteristics. The basic shape evaluated was for a rectangular section with height-to-width ratio = 0.835 and its companion in the duplex mode (half model testing) with height-to-width ratio = 0.6. A best overall basic configuration was determined with seven slots on each wall with open area ratio on each wall of 17.5%. For both full-span and half-model testing, the optimum solution required closing all but two slots on each of the half-walls parallel to the plane of the wing (equivalent to four slots on the full floor and ceiling). The results are presented here for the best configurations and are shown to be within the figure-of-merit range of + or - 0.04 in upwash, and + or - 0.1 in curvature for the Mach number range 0.6 to 0.85. Blockage effects are shown to be small.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-TM-86002 , A-9845 , NAS 1.15:86002
    Format: application/pdf
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  • 6
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    Calculation of transonic steady and oscillatory pressures on a low aspect ratio model and comparison with experiment (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Pressure data measured by the British Royal Aircraft Establishment for the AGARD SMP tailplane are compared with results calculated using the transonic small perturbation code XTRAN3S. A brief description of the analysis is given and a recently developed finite difference grid is described. Results are presented for five steady and nine harmonically oscillating cases near zero angle of attack and for a range of subsonic and transonic Mach numbers.
    Keywords: AERODYNAMICS
    Type: NASA-TM-86449 , NAS 1.15:86449
    Format: application/pdf
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  • 7
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    Some remarks on the design of transonic tunnels with low levels of flow unsteadiness (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The principal sources of flow unsteadiness in the circuit of a transonic wind tunnel are presented. Care must be taken to avoid flow separations, acoustic resonances and large scale turbulence. Some problems discussed are the elimination of diffuser separations, the aerodynamic design of coolers and the unsteadiness generated in ventilated working sections.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: NASA-CR-2722
    Format: application/pdf
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  • 8
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    Some remarks on dynamic aeroelastic model tests in cryogenic wind tunnels (1975)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Keywords: GENERAL
    Type: NASA-CR-145029
    Format: application/pdf
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  • 9
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    Technical evaluation report of AGARD Technical Evaluation Meeting on Unsteady Aerodynamics: Fundamentals and Applications to Aircraft Dynamics (1986)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: From May 6 to 9, 1985, the Fluid Dynamics Panel and Flight Mechanics Panel of AGARD jointly arranged a Symposium on Unsteady Aerodynamics-Fundamentals and Applications to Aircraft Dynamics at the Stadthall, Goettingen, West Germany. This Symposium was organized by an international program committee chaired by Dr. K. J. Orlik-Ruckemann of the Fluid Dynamics Panel. The program consisted of five sessions grouped in two parts: (1) Fundamentals of Unsteady Aerodynamics; and (2) Applications to Aircraft Dynamics. The 35 papers presented at the 4 day meeting are published in AGARD CP 386 and listed in the Appendix. As the papers are already available and cover a very wide field, the evaluators have offered brief comments on every paper, followed by an overall evaluation of the meeting, together with some general conclusions and recommendations.
    Keywords: AERODYNAMICS
    Type: AGARD-AR-222 , AD-A167592 , May 06, 1985 - May 09, 1985; Goettingen; Germany
    Format: text
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