Values of three mean velocity components and six turbulence stresses measured in a juncture flow are presented and discussed. The juncture flow is generated by a constant thickness body, having an elliptical leading edge, which is mounted perpendicular to a large flat plate along which a turbulent boundary layer is growing. The measurements were carried out at two streamwise stations in the juncture and were made using two single sensor hot-wire probes. The secondary flow in the juncture results in a considerable distortion in the mean velocity profiles. The secondary flow also transports turbulence in the juncture flow and has a large effect on the turbulence stresses. From visual inspection of the results, there is considerable evidence of similarity between the turbulent shear stresses and the mean flow strain rates. There is some evidence of similarity between the variations in the turbulent stress components.

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Mean velocities and Reynolds stresses in a juncture flow

A design method is presented whereby the flow separation in the wing-fuselage juncture of aircraft is eliminated by the use of a leading-edge fillet. The design method uses a design rule that relates a change in skin friction to a change in surface slope. After determining the current skin friction distribution on the plate ahead of the leading edge of the wing, a target skin friction distribution that will eliminate flow separation is calculated. Using the design rule, the current skin friction distribution is moved toward the target distribution by extending the leading edge of the wing to form a leading-edge fillet. The new leadingedge fillet is then analyzed by the flow solver and the process is iterated until convergence is achieved. Nomenclature

Method for Designing Leading-Edge Fillets to Eliminate Flow Separation

Three foil sections with different thickness ratios are theoretically designed to delay cavitation inception and give high lift/ drag ratio. The thickness to chord ratios are 3.86%, 6.48% and 9.71%, respectively. Cavitation performance as well as noncavitating performance are examined by the noncavitating and cavitating foil theories, and by cavitation tunnel tests such as hydrodynamic force measurement and cavitation observation. From these test results, the foil performance and design method are evaluated as well as the accuracy of the theoretical prediction is discussed. It is found that the present designs have been successful.

High peformance foil sections with delayed cavitation inception

: Historically, two-dimensional airfoil or hydrofoil section characteristics have been obtained by measuring individually the lift, drag and pitching moment by the most accurate technique available. The use of force balances to measure the three quantities simultaneously has met with only partial success. although the lift and pitching moment data have usually been acceptable, the drag data have varied by as much as an order or magnitude from previous reference data. To investigate the parameters which influence two-dimensional force measurements, an experimental program was conducted in the subsonic wind tunnel of the Applied Research Laboratory at The Pennsylvania State University. From the results of this test program, the sidewall boundary layer was identified as the primary factor contributing to the erroneous drag measurements. A correction procedure which is based on the airfoil/hydrofoil geometry, the flow environment and the measured data was developed. Corrected data from the subject test probram and from similar programs in other experimental facilities for both symmetrical and cambered sections are in good agreement with the reference data in all cases. (Author)

Sidewall Boundary-Layer Corrections in Subsonic, Two-Dimensional Airfoil/Hydrofoil Testing

: Historically, two-dimensional airfoil or hydrofoil section characteristics have been obtained by measuring individually the lift, drag and pitching moment by the most accurate technique available. The use of force balances to measure the three quantities simultaneously has met with only partial success. Although the lift and pitching moment data have usually been acceptable, the drag data have varied by as much as an order of magnitude from the accepted NACA reference data. To investigate the parameters which influence two-dimensional force measurement and force balance design, an experimental program was conducted in the subsonic wind tunnel of the Applied Research Laboratory at the Pennsylvania State University (ARL/PSU). From the results of this test program the sidewall boundary layer was identified as the primary factor contributing to the erroneous drag measurements. A correction procedure which is based on the airfoil/hydrofoil geometry, the flow environment and the measured data was developed. Corrected data from the subject test program and from similar programs in other experimental facilities for both symmetrical and cambered sections are in good agreement with NACA data in all cases. (Author)

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G. B. Gurney

Papers

Sidewall Boundary-Layer Corrections in Subsonic, Two-Dimensional Airfoil/Hydrofoil Testing

Correcting for the Sidewall Boundary Layer in Subsonic Two-Dimensional Airfoil/Hydrofoil Testing.

Sidewall boundary layer corrections in subsonic, two-dimensional airfoil/hydrofoil testing