Turbulence in the Wake of a Thin Airfoil at Low Speeds

Author: Campbell, George Stuart

Year: 1956

Degree: Dissertation (Ph.D.)

Advisor: Liepmann, Hans Wolfgang

Committee Member: Unknown, Unknown

Option: Aeronautics; Mathematics

DOI: 10.7907/T35K-QF86

Abstract

Experiments have been made to determine the nature of turbulence in the wake of a two-dimensional airfoil at low speeds. The experiments were motivated by the need for data which can be used for analysis of the tail-buffeting problem in aircraft design. Turbulent intensity and power spectra of the velocity fluctuations were measured at a Reynolds number 1.6 x 10[superscript 5] for several angles of attack. Total-head measurements were also obtained in an attempt to relate steady and fluctuating wake properties.

Mean-square downwash was found to have nearly the same dependence on vertical position in the wake as that shown by total-head loss. For this particular wing, turbulent intensity, integrated across the wake, increased roughly as the 3 /2 power of the drag coefficient.

Power-spectrum measurements indicated a decrease in frequency as wing angle of attack was increased. The average frequency in the wake was proportional to the ratio of mean wake velocity to wake width.

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