Experimental testing at transonic speeds
01 Jan 1982-Vol. 81, pp 189-238
TL;DR: In this paper, the authors defined the normal force and pitch moment coefficients of a wing span and its chord, and the slope of a section normal force vs angle-of-a attack curve.
Abstract: Nomenclature b = wing span c = wing chord c , = section drag coefficient d c = section lift coefficient c = section normal force coefficient n c = slope of section normal force vs angle-ofa attack curve c = section pitching moment coefficient C = aircraft drag coefficient C = aircraft lift coefficient LI C = pressure coefficient Cju = blowing coefficient M = Mach number P = total pressure q , q = freestream dynamic pressure
Citations
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TL;DR: In this article, the transonic flow around a low-aspect-ratio infinite wing in a wind tunnel is investigated by means of numerical simulations, with a focus on shock-induced separated flows.
19 citations
01 Jan 1984
TL;DR: In this article, an investigation was carried out on two CAST 10-2 airfoil models with chords of 3 in. and 6 in. The tests were conducted in the Langley 0.3m Transonic Cryogenic Tunnel two-dimensional test section equipped with an upstream sidewall boundary layer removal system.
Abstract: An investigation was carried out on two CAST 10-2 airfoil models with chords of 3 in. and 6 in. To evaluate the extent of sidewall influence on airfoil tests at transonic Mach numbers. The tests were conducted in the Langley 0.3-m Transonic Cryogenic Tunnel two-dimensional test section equipped with an upstream sidewall boundary layer removal system which reduces the boundary layer displacement thickness to about 1 percent of model halfspan from an initial 2 percent without boundary layer removal. Test results have shown the changes in the location of the shock on the upper surface of the airfoil to be about the same for both models with and without sidewall boundary layer removal. Even though large differences were noted in the high lift characteristics of the two models, the sidewall boundary layer removal had little effect on the differences. These tests also served to validate the boundary layer removal technique and the associated Mach number correction required with upstream boundary layer removal.
11 citations
15 Jan 1979
1 citations
22 Oct 2019
TL;DR: This revision of the model representation is based on high fidelity free-air CFD solutions for the NASA Common Research Model, validated by experimental data sets obtained from a semispan version of the CRM tested at the NRC 5ft Trisonic Wind Tunnel.
Abstract: The National Research Council 5ft Trisonic Wind Tunnel enables testing of half-span models at a high Reynolds number cost effectively, however there is the possibility of experiencing relatively larger wall-interference effects compared to full span tests. Subsonic wall-interference effects due to the partially open boundaries at the NRC 5ft wind tunnel are corrected by the “one-variable” method, resulting in corrections in Mach number and angle of attack for the measured quantities. This dissertation introduces the need for adequately correcting for wall interference in subsonic half-model wind-tunnel testing in both pre-stall and post-stall conditions. The one-variable method is described and several aspects that require validation and improvement in this method are pointed out based on specific experimental and numerical results obtained for different test articles.
An initial assessment of the influence of the different possible tunnel configurations and computational parameters is defined based on experimental data from a test performed on a scaled model of the Bombardier Global 6000 business jet. This initial study unveils some of the weaknesses of the one-variable method. While this method provides accurate wall corrections during tests in pre-stall conditions; it is unable to generate reliable corrections in stall. Partially, this is due to the development of flow separation on a model tested at subsonic flow conditions reaching stall, not currently accounted for by the potential theory model representation used by the wall-correction methodology at the NRC 5ft TWT. Possible improvements to this singularity representation, paramount to the one-variable method, are then investigated. This revision of the model representation is based on high fidelity free-air CFD solutions for the NASA Common Research Model, validated by experimental data sets obtained from a semispan version of the CRM tested at the NRC 5ft Trisonic Wind Tunnel. The improved potential representation is tested on solid-wall experimental wind-tunnel data to present more reliable behavior of the wall-interference correction estimates when substantial wing stalling is encountered.
01 Jan 1987
TL;DR: In this paper, a simplified fourwall interference assessment method has been described, and a computer program developed to facilitate correction of the airfoil data obtained in the Langley 0.3m Transonic Cryogenic Tunnel (TCT).
Abstract: A simplified fourwall interference assessment method has been described, and a computer program developed to facilitate correction of the airfoil data obtained in the Langley 0.3-m Transonic Cryogenic Tunnel (TCT). The procedure adopted is to first apply a blockage correction due to sidewall boundary-layer effects by various methods. The sidewall boundary-layer corrected data are then used to calculate the top and bottom wall interference effects by the method of Capallier, Chevallier and Bouinol, using the measured wall pressure distribution and the model force coefficients. The interference corrections obtained by the present method have been compared with other methods and found to give good agreement for the experimental data obtained in the TCT with slotted top and bottom walls.
References
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41 citations
TL;DR: In this paper, a symmetrical NACA 64A010 airfoil section at transonic conditions was measured for three angles of attack with the freestream Mach number fixed at O.S.
Abstract: Flowfield measurements are presented for a symmetrical NACA 64A010 airfoil section at transonic conditions. Measurements were obtained for three angles of attack with the freestream Mach number fixed at O.S. The cases studied included a weak shock-wave/boundary-layer interaction, an interaction of medium strength with mild separation, and an interaction of sufficient strength to produce a shock-induced stall situation. Two nonintrusive optical techniques, lower velocimetry and holographic interferometry, were used to characterize the flows. The results include Mach number contours and flow angle distributions in the inviscid flow regions, and turbulent flow properties, including the turbulent Reynolds stresses, of the upper surface viscous layers, and of the near-wake. The turbulent flow measurements reveal that the turbulence fluctuations attain equilibrium with the local mean flow much faster than previously expected.
39 citations
01 Jan 1966
TL;DR: In this paper, discrepancies between wind tunnel predictions and actual flight test results for conditions of supercritical separated flow were found. But they were not discussed in terms of flight test performance.
Abstract: Discrepancies between wind tunnel predictions and actual flight test results for conditions of supercritical separated flow
38 citations
01 Jan 1976
TL;DR: In this paper, a modified small-disturbance (MSD) was proposed and shown to be a consistent approximation to the full potential equation over a wider range of sweep angles.
Abstract: Relaxation solutions to classical three-dimensional small-disturbance (CSD) theory for transonic flow about lifting swept wings are reported. For such wings, the CSD theory was found to be a poor approximation to the full potential equation in regions of the flow field that are essentially two-dimensional in a plane normal to the sweep direction. The effect of this deficiency on the capture of embedded shock waves in terms of (1) the conditions under which shock waves can exist and (2) the relations they must satisfy when they do exist is emphasized. A modified small-disturbance (MSD) equation, derived by retaining two previously neglected terms, was proposed and shown to be a consistent approximation to the full potential equation over a wider range of sweep angles. The effect of these extra terms is demonstrated by comparing CSD, MSD, and experimental wing surface pressures.
32 citations
01 Jan 1976
TL;DR: In this article, a reference record was created on 2005-11-18, modified on 2016-08-08 and used for the transsonique reference record, which was used for this paper.
Abstract: Keywords: ecoulement : instationnaire ; hodographe ; ecoulement : interne ; methodes : numeriques ; ecoulement : transsonique Reference Record created on 2005-11-18, modified on 2016-08-08
25 citations