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  • 1
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    Wind tunnel wall interference correction for aircraft models (1984)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Wall interference correction procedures seek to determine the required changes in certain flow or geometric parameters so that the difference between the flow properties at the model's surface in the tunnel and free air are minimized. A transonic and a linear correction procedure were developed for aircraft models. In addition to Mach number and angle of attack corrections, an estimate of the accuracy of the corrections is provided by the transonic correction procedure. Lift, pitching moment and pressure measurements near the tunnel walls are required. The efficiency and accuracy of the correction procedure are improved. Moreover, correction of both the wing and tail angles of attack is allowed. The procedure is valid for transonic as well as subcritical flows. However, for subcritical flows further approximations and simplifying assumptions are made, leading to a very simple and efficient correction procedure.
    Keywords: AERODYNAMICS
    Type: NASA. Langley Research Center. Wind Tunnel Wall Interference Assessment and Correction, 1983; p 301-322
    Format: text
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  • 2
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    Wind-tunnel wall interference corrections for three-dimensional flows (1982)
    In:  Other Sources
    Details
    Publication Date: 2011-08-18
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional aircraft configurations is presented. The Mach number and angle-of-attack corrections are obtained by numerically solving the Laplace equation in a parallelepiped with boundary conditions supplied mainly from experimental pressure measurements. A portion of these measurements and other wind-tunnel data required by the procedure may be replaced by theoretical estimates if not available from experiments. The accuracy of the correction results will then depend on the accuracy of these estimates. The correction procedure is applied to an isolated wing and to a wing-tail configuration in a solid-wall wind tunnel. It is found that neglecting twist and camber corrections for the wing effectively increases the tail angle-of-attack correction. Two different Mach number corrections can be calculated for the wing and tail. However, since only one Mach number correction is allowed for both the wing and the tail, and since the wing surface area is larger than the tail surface area, the final correction tends to be closer to the required wing correction. This is a source of error for the tail results.
    Keywords: AERODYNAMICS
    Type: Journal of Aircraft; 19; June 198
    Format: text
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  • 3
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    Two-dimensional transonic wind-tunnel wall interference corrections based on the Euler equations (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A procedure for the evaluation of wall interference corrections for two-dimensional models is presented. The Mach number and angle-of-attack corrections require the numerical solution of the Euler equations. Pressure measurements are required near the wind tunnel walls. The correction procedure also requires knowledge of the free-stream Mach number, the model geometry, and the lift force experienced by the model. The residual interference not accounted for by the Mach number and angle-of-attack corrections is estimated.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 86-0124
    Format: text
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  • 4
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    Propeller design by optimization (1986)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The feasibility of designing propellers by an optimization procedure is investigated. A scheme, which solves the full potential flow equation about a propeller by line relaxation, is modified so that the iterative solutions of the flow equation and the design parameters are updated simultaneously. Some technical problems in using optimization for designing propellers with maximum efficiency are identified. Approaches for overcoming these problems are presented.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 86-0081
    Format: text
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  • 5
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    Aerodynamic optimization by simultaneously updating flow variables and design parameters (1990)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The application of conventional optimization schemes to aerodynamic design problems leads to inner-outer iterative procedures that are very costly. An alternative approach is presented based on the idea of updating the flow variable iterative solutions and the design parameter iterative solutions simultaneously. Two schemes based on this idea are applied to problems of correcting wind tunnel wall interference and optimizing advanced propeller designs. The first of these schemes is applicable to a limited class of two-design-parameter problems with an equality constraint. It requires the computation of a single flow solution. The second scheme is suitable for application to general aerodynamic problems. It requires the computation of several flow solutions in parallel. In both schemes, the design parameters are updated as the iterative flow solutions evolve. Computations are performed to test the schemes' efficiency, accuracy, and sensitivity to variations in the computational parameters.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AGARD, Computational Methods for Aerodynamic Design (Inverse) and Optimization; 18 p
    Format: text
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  • 6
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    Wind tunnel wall interference corrections for aircraft models in the transonic regime (1984)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional models is presented. In addition to Mach number and angle-of-attack corrections, the procedure provides an estimate of the accuracy of the corrections. Lift, pitching moment, and pressure measurements near the tunnel walls are required by the correction method. The method is demonstrated by application to an isolated wing model and to a wing-body-tail configuration.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: Journal of Aircraft (ISSN 0021-8669); 21; 54-61
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  • 7
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    Aerodynamic effects of nearly uniform slipstreams on thin wings in the transonic regime (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A simplified model is used to describe the interaction between a propeller slipstream and a wing in the transonic regime. The undisturbed slipstream boundary is assumed to coincide with an infinite circular cylinder. The undisturbed slipstream velocity is rotational and is a function of the radius only. In general, the velocity perturbation caused by introducing a wing into the slipstream is also rotational. By making small disturbance assumptions, however, the perturbation velocity becomes nearly potential, and an approximation for the flow is obtained by solving a potential equation.
    Keywords: AERODYNAMICS
    Type: NASA-CR-152351
    Format: application/pdf
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  • 8
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    Transonic wind tunnel wall interference corrections for three-dimensional models (1982)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A procedure for the evaluation of wall interference corrections for three-dimensional models is presented. The Mach number and angle-of-attack corrections require the numerical solution of the potential equation about a simplified representation of the experimental model. Pressure measurements are required near the wind tunnel walls. The correction procedure also requires knowledge of the free-stream Mach number, the model angle of attack, and the lift force experienced by the model. The procedure provides an estimate of the accuracy of the correction. For slender configurations at Mach numbers close to one, the Equivalence Rule formulation is adopted to calculate the wall interference effects. Preliminary results are presented for both general and slender-body configurations.
    Keywords: RESEARCH AND SUPPORT FACILITIES (AIR)
    Type: AIAA PAPER 82-0588 , In: Aerodynamic Testing Conference; Mar 22, 1982 - Mar 24, 1982; Williamsburg, VA
    Format: text
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  • 9
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    Propeller slipstream/wing interaction in the transonic regime (1980)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: An inviscid model for the interaction between a thin wing and a nearly uniform propeller slipstream is presented. The model allows the perturbation velocities due to the interaction to be potential although the undisturbed slipstream velocity is rotational. A finite difference scheme is used to solve the governing equation. Numerical examples indicate that the slipstream has a strong effect on the aerodynamic properties of the wing section within the slipstream and lesser effects elsewhere. The slipstream swirling motion strongly affects the wing load distribution, however, its effect on the wing's total lift and wave drag is small. The axial velocity increment in the slipstream has a small effect on the wing lift, however, it causes a large increase in wave drag.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 80-0125 , Aerospace Sciences Meeting; Jan 14, 1980 - Jan 16, 1980; Pasadena, CA
    Format: text
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  • 10
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    Axisymmetric internal flows with shocks (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Internal flow problems with supersonic entrance conditions and subsonic exit conditions are studied. The suitability of applying the transonic-small disturbance theory to internal flows is examined and found to be very limited. The full inviscid equations in nonconservative form are solved by relaxation. Jump conditions which conserve mass and normal momentum are applied explicitly at shock waves. This method is suitable for solving flows which include supersonic-subsonic shock waves nearly normal to the streamlines.
    Keywords: AERODYNAMICS
    Type: AIAA PAPER 79-0015 , American Institute of Aeronautics and Astronautics, Aerospace Sciences Meeting; Jan 15, 1979 - Jan 17, 1979; New Orleans, LA
    Format: text
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