Experiment

Graphic showing experiment setup

Results are presented from a towing-tank experiment of 3D separation and free-surface turbulence to provide detailed documentation of the flow appropriate both for explicating the flow physics and validating computational methods.  The model is NACA24 which is a 1.2 m chord length, vertical, surface-piercing hydrofoil.  The data includes far and near field wave elevations, surface pressures, and wave profiles on the hull at three Froude numbers (Fr= 0.19, 0.37, 0.55).

Data, Equipment, and Conditions

Data Equipment Fr Locations
Wave profiles Markers and video 0.19, 0.37, 0.55 x / c = 0-1; Dx / c = 0.025
Near field wave elevations Servo-type wave gages 0.19, 0.37 x / c = -0.50-1.50, y / c = 0-0.459
Far field  wave elevations Capacitance wires 0.19, 0.37, 0.55 x / c = -2.0-3.0, y / c = 0.135-1.01
Surface pressures Pressure transducers 0.19, 0.37, 0.55 x / c = 0.0613-0.8613, z / c = -0.9304-0.0854

Sample Image

Front-quarter view of the bow flow around the NACA24 shows a sharp wave elevation increase at x/ c = 0, separated flow downsteam of the bow wave, and significant free-surface turbulence.

Front-quarter view of the bow flow around the NACA24

Sample Data

Near and far field wave elevation contours for Fr = 0.37.

Graphic showing near and far field wave elevation contours for Fr = 0.37.

References:

Abbott, I.H. and Von Doenhoff, A.E., (1959), “Theory of Wing Sections,” Dover Publications Inc., New York, 693 pp.

Zhang, Z. and Stern, F., (1996), “Free-Surface Wave-Induced Separation,” ASME J. Fluids Eng., Vol. 118, pp. 546–554.

Kandasamy, K., Wilson, R., and Stern, F., (2001), “Unsteady RANS Simulation of Free-surface Wave-induced Separation,” Proc. 26th ATTC, Webb Institute, Glen Cove, N.Y.

Metcalf, B., Longo, J., and Stern, F., (2001), “Experimental Investigation of Wave-induced Separation Around a Surface-piercing Hydrofoil,” Proc. 26th ATTC, Webb Institute, Glen Cove, N.Y.

Metcalf, B., (2001), “Experimental Investigation of Free-surface Wave-induced Separation Around a Surface-piercing NACA0024 Hydrofoil,” M.S. thesis, Department of Mechanical Engineering, University of Iowa, Iowa City, IA., 143pp

Metcalf, B., Longo, J., Ghosh, S., and Stern, F., (2006), “Unsteady Free-surface Wave-induced Boundary-layer Separation for a Surface-piercing NACA 0024 Foil: Towing Tank Experiments,” J. Fluids & Structures, Vol. 22, 77–98pp.