Research on Adaptive Wall Wind Tunnels


Book Description

The objective of this research was to investigate the utility of the Calspan self-correcting wind tunnel for minimizing or eliminating wall interference effects in two-dimensional transonic flows when shock waves from the test model extend to the tunnel walls. This report summarizes the experimental research performed with two-dimensional airfoils in the Calspan self-correcting wind tunnel and the theoretical research accomplished in support of the experiments. The experiments were performed with airfoil models having 4% and 6% solid blockage. The initial experiments with the 6%-blockage model were devoted to determining a practical mode of operation when shock waves from the model extend to the wall. The most practical model is to use wall control to obtain the desired distribution of longitudinal velocity components for subcritical walls. The Mach number is then increased and the wall control is readjusted, sequentially, until the desired test condition is achieved. At the high Mach numbers of interest, however, the available wall control was limited locally, and tunnel system changes were required. A method is reported for analyzing self-correcting wind tunnels with porous walls.




Research on Adaptive Wall Wind Tunnels


Book Description

The objective of this research was to investigate the utility of the Calspan self-correcting wind tunnel for minimizing or eliminating wall interference effects in two-dimensional transonic flows when shock waves from the test model extend to the tunnel walls. This report summarizes the experimental research performed with two-dimensional airfoils in the Calspan self-correcting wind tunnel and the theoretical research accomplished in support of the experiments. The experiments were performed with airfoil models having 4% and 6% solid blockage. The initial experiments with the 6%-blockage model were devoted to determining a practical mode of operation when shock waves from the model extend to the wall. The most practical model is to use wall control to obtain the desired distribution of longitudinal velocity components for subcritical walls. The Mach number is then increased and the wall control is readjusted, sequentially, until the desired test condition is achieved. At the high Mach numbers of interest, however, the available wall control was limited locally, and tunnel system changes were required. A method is reported for analyzing self-correcting wind tunnels with porous walls.




Adaptive Wall Wind Tunnels


Book Description




Adaptive Wall Wind Tunnels


Book Description




Experiments in a Three-Dimensional Adaptive-Wall Wind Tunnel


Book Description

Three dimensional adaptive-wall experiments were performed in the Ames Research Center (ARC) 25- by 13-cm indraft wind tunnel. A semispan wing model was mounted to one sidewall of a test section with solid sidewalls, and slotted top and bottom walls. The test section had separate top and bottom plenums which were divided into streamwise and cross-stream compartments. An iterative procedure was demonstrated for measuring wall interference and for adjusting the plenum compartment pressures to eliminate such interference. The experiments were conducted at a freestream Mach number of 0.60 and model angles of attack between 0 and 6 deg. Although in all the experiments wall interference was reduced after the plenum pressures were adjusted, interference could not be completely eliminated. Schairer, E. T. Ames Research Center NASA-TP-2210, A-9255, NAS 1.60:2210 RTOP 505-31-51...




AGARD Advisory Report


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An Experimental Study of an Adaptive-Wall Wind Tunnel


Book Description

A series of adaptive wall ventilated wind tunnel experiments was carried out to demonstrate the feasibility of using the side wall pressure distribution as the flow variable for the assessment of compatibility with free air conditions. Iterative and one step convergence methods were applied using the streamwise velocity component, the side wall pressure distribution and the normal velocity component in order to investigate their relative merits. The advantage of using the side wall pressure as the flow variable is to reduce the data taking time which is one the major contributors to the total testing time. In ventilated adaptive wall wind tunnel testing, side wall pressure measurements require simple instrumentation as opposed to the Laser Doppler Velocimetry used to measure the velocity components. In ventilated adaptive wall tunnel testing, influence coefficients are required to determine the pressure corrections in the plenum compartment. Experiments were carried out to evaluate the influence coefficients from side wall pressure distributions, and from streamwise and normal velocity distributions at two control levels. Velocity measurements were made using a two component Laser Doppler Velocimeter system. Celik, Zeki and Roberts, Leonard Unspecified Center FLOW DISTRIBUTION; INFLUENCE COEFFICIENT; PRESSURE DISTRIBUTION; WALL PRESSURE; WIND TUNNEL TESTS; WIND TUNNEL WALLS; CONVERGENCE; FREE FLOW; LIFT; MACH NUMBER; PLENUM CHAMBERS; VELOCITY MEASUREMENT; VENTING...




(Les Souffleries À Paroi Adaptable)


Book Description

This report presents the results of a study by Working Group 12 of the Fluid Dynamics Panel of AGARD on adaptive-wall wind tunnels. This presentation reviews the history and state of the art of adaptive-wall technology with regard to both the various streamlining algorithms and the existing adaptive-wall facilities; discusses limitations and open questions of adaptive-wall methods and compares them with passive-wall correction techniques: assesses residual wall interferences; presents the prospects for high-productivity and unsteady flow testing with adaptive walls; and males recommendations for future developments. The participants in WG12 represented Canada, France, Federal Republic of Germany, Italy, Netherlands, Turkey, United Kingdom, and United States.