Adaptive-Wall Wind-Tunnel Investigations

Abstract : The results of a program of research on transonic wind tunnels with adaptive walls for eliminating wall interference are presented. A description is given of related experimental research performed at other laboratories using several alternative methods for controlling the flow. Features of the segmented- plenum, perforated-wall, two-dimensional test section of the Calspan One-Foot Tunnel and the associated instrumentation for measuring the flow disturbance quantities are reviewed and necessary modifications made to the original experimental configuration are described. Details of adaptive-wall iteration experiments with a 4%-blockage NACA 0012 airfoil model are presented, particularly those at a free-stream Mach number of 0.9 and nominal angles of attack of 3, 2 and 1 deg. In these experiments, regions of supercritical flow terminated by shock waves extended to the tunnel walls. The results of the experiments indicate that successful iterations toward interference-free flow conditions are achieved. For another phase of the research, conceptual design studies of a three-dimensional transonic adaptive-wall test section using the segmented-plenum, perforated-wall method of flow control are reported. Finally, numerical simulations of low-speed flow within the Calspan test section, including the interaction of the transpired boundary layer at the walls with the flow over the model, are described in AIAA Paper No. 81-0160, which is appended to the report.