Numerical Study of Flow and Thrust Produced by Heaving and Combined Oscillation of 2D Hydrofoil

概要

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Unsteady viscous flow field around an oscillating 2D hydrofoil is studied numerically. The main objectives are to study the flow phenomena and the abilities of an oscillating foil to produce thrust. In the general case, the foil is performing a combination of symmetric pitching, heaving and surging oscillations, Numerical simulations are performed over a modified NAC0012 foil. Investigations consider the basic flow features and the effect of main governing parameters. Flow is simulated by solving the full 2D unsteady Navier-Stokes equations, in a vorticity-stream function formulation. An implicit numerical algorithm and a compact finite difference scheme are employed. The validity of the flow simulation is studied through the comparison with the available experimental results. Flow analysis designates that the strong unsteady viscous effects with massive flow separation and intensive vortical structures are valid for the most of the studied motions. Such flow patterns are result of the leading and trailing edge separation and the further flow evolution including a complicated wake interaction. From a propulsive point of view, the combined pitching and heaving motion with a shifted phase of pitching is the most effective one. Surging oscillations introduce additional dynamic effects. Governing parameters have an interrelated influence on the flow penomena and induced forces.
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