Airfoil characteristics measured in a wind tunnel typically differ from those obtained in free air due to the confinement of airflow in tunnel test sections and the development of boundary layer on tunnel walls. Wind tunnel measured quantities, e.g. Mach number, Reynolds number, angle of attack, require corrections to determine their equivalent values in free air. TWNTN4A is a correction program capable of correcting wall interference effects in 2-D wind tunnels. TWNTN4A was applied to correct over 300 data files obtained from tests performed in 0.3m Transonic Cryogenic Tunnel (TCT) at NASA Langley. Data describe Mach number range of 0.50 ~ 0.82, angle of attack ~ 13, and Reynolds number 3,000,000 and 9,000,000. As a new feature, variable grid control has been introduced to the correction code, and semi-automatic procedure was developed to achieve volume processing of experimental data files. Most of the corrected results correlated well with an interference free viscous numerical solution given by Swanson/Turkel. However, results from variable grid control questioned the validity of numerical scheme used for lower Mach number cases (M = 0.50 ~ 0.65), which requires further analysis in the future.

Library of Congress Subject Headings

Wind tunnels; Wind tunnel walls; Transonic wind tunnels; Wall pressure (Aerodynamics); Air resistance

Publication Date


Document Type


Department, Program, or Center

Mechanical Engineering (KGCOE)


Ghosh, Amitabha

Advisor/Committee Member

Venkataraman, P.

Advisor/Committee Member

Kochersberger, Kevin


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