Test Verification of a Transonic Airfoil Design Employing Active Diffusion Control.
Abstract
Experimental results are presented that show active diffusion control, with its integrated contouring/blowing characteristics, to be a viable concept for relaxing transonic airfoil design constraints. The antiseparation tailored contour (ATC) is the basic device for active diffusion control. A modified 12% thick C-141 section with a trailing edge upper surface ATC, designated as the TEATC12 airfoil, was selected as the proof-of-concept configuration. It incorporates the main features of active diffusion control while providing a reliable baseline for comparison. Previous analytical studies have predicted a near-critical 'roof-top' pressure distribution at the design point and the potential for superior off-design performance. The experimental verification has been obtained in two steps. In the first step, the transonic BLC/diffusion process was modeled in an axisymmetric diffuser facility. Blowing predictions for the ATC geometry were substantiated and interactions between the jet and the mainstream were examined. Experimental verification was completed by testing a TEATC12 airfoil model in the Vought Systems Division High Speed Wind Tunnel. A C-141 model was also tested to provide a direct reference for the TEATC12 results. Wind tunnel data validate the TEATC12 design point at predicted lift/blowing and show the design point advantages carrying over to off-design performance. Buffet onset lift coefficients 0.2 higher than those for either shockless supercritical or conventional sections were obtained at M = 0.70 and drag divergence was delayed by 0.13 on Mach number relative to comparable conventional sections.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1975
- Accession Number
- ADA024297
Entities
People
- C. H. Haight
- J. G. Spangler