### Hydrofoil Flow

THIS INTERACTIVE JAVA APPLET WAS DEVELOPED AT UT AUSTIN BY Chris Jenkins AND Lino Geo Lino Bailey, UNDER THE SUPERVISION OF PROFESSOR. Spyros A. Kinnas, 2000.

PERMISSION TO LINK TO THIS JAVA APPLET AND TO DOWNLOAD OR TO USE THE RELATED JAVA SOURCE CODE, MUST BE GRANTED BY PROFESSOR Spyros A. Kinnas ( kinnas@mail.utexas.edu ).

#### Purpose:

This applet uses a numerical method (a panel method based on the total velocity potential) to calculate and plot the pressures on the surface of a hydrofoil subject to a uniform inflow.

#### Assumptions:

• The flow is assumed to be inviscid and incompressible (rho is the density of the fluid).
• The hydrofoil is a NACA 4-digit thickness form combined with parabolic camber.
• The inflow velocity vector is U, the chord of the foil c, and the ambient pressure po.
• The values of U, c, rho, and po are not needed as the pressures along the foil surface are given in terms of the negative pressure coefficient, defined as -Cp=-(p-po)/(0.5*rho*U^2)
• Arc lengths are approximated in the calculation using the linear distance between panel discretization points.

#### Using the applet:

• Click on 'Open Window' to start the applet.
• Input the angle of attack in degrees and press enter.
• Input the max. camber/chord, f/c, in the range [-0.25, 0.25] and press enter to determine the mean camberline distribution.
• Input the max. thickness/chord, t/c, in the range [0.025, 0.5] and press enter to determine the thickness distribution.
• Choose the number of panels, N, in the range [60, 200].  N must be even in order to use the same number of panels at the top and the bottom of the foil.
• Click on 'Go' to begin calculating the influence coefficients and solve for the potential distribution on the foil surface. The location of the panel mid-points (also called the control points) is shown on the screen (starting from the bottom trailing edge), together with the normal vector on all other panels and the corresponding subtended angles (both used in the calculation of the influence coefficients).
• Once the calculation is completed, the computed -Cp along the top side (called the suction side or the "back") and the bottom side (called the pressure side or the "face") of the foil will show in a separate pop-up window. You can enlarge, close or leave open the pop-up window with the results. You can change the foil characteristics or number of panels and perform as many more runs as you wish (...or as many open windows you can take)
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Last Revised: May 25, 2000