Numerical Simulation of Transient Flows around a 3D Pitching Hydrofoil

Abstract

The objective of this paper is to investigate the hydrodynamic characteristics of the transient flows around a 3D pitching hydrofoil via numerical studies, where the effects of tunnel wall boundary layer and gap flows are considered. Simulations are performed using an unsteady Reynolds Average Navier-Stokes solver and the k-ω SST turbulence model, coupled with a two-equation γ-Reθ transition model. Hydrodynamic forces and flow structures are compared to the results with the equivalent 2D computations. During the upward pitching stage, the transition phenomenon is accurately captured by both the 2D and 3D simulations. The slightly lower lift and suction side loading coefficients predicted by the 3D simulation are due to the pressure effects caused by the tip gap flow. During the dynamic stall stage, the 2D case exhibits a clear overshoot on the hydrodynamic force coefficients and the 3D simulation results better agree with the experimental results. During the downward pitching stage, the flow transitions back to laminar. As for the effect of gap flow and the wall boundary condition, the gap flow causes disturbances to the formation and development of the vortex structures, resulting in the complex distribution of the three-dimensional streamlines and the particle path.

Numerical study on drag reduction and wake modification for the flows over a hydrofoil in presence of surface heterogeneity

“…Effective slip length is calculated by the mean velocity over the surface of hydrofoil constructed through alternating slip and no-slip surfaces. Then it is obtained based on the definition of the slip length represented in equation (1). Amount of slip is quantified through slip length.…”

“…Hydrofoil as a basic structural unit is frequently applied in ship and marine engineering to supply sufficient lift force or maneuvering control ability for ship and underwater structures as well as energy harvesting equipment, and so on. [1][2][3][4][5][6] The essential requirement of hydrofoil is to provide a wide range of lift force with a relative low drag resistance cost. Many attempts are devoted to improve and study the influence of such hydrodynamic characteristics.…”

Analysis of Near-wall effect on cloud cavitating flow that surrounds an axisymmetric projectile using large eddy simulation with Cartesian cut-cell mesh method

“…Traditional experimental methods include water tank test [17] and water tunnel test [18]. The CFD simulation method has also become increasingly popular in solving hydrodynamic problems; the tools adopted for this method include commercial [19,20], open-source [21,22] and inhouse [23][24][25] software. Typical problems include cavitating flow of unsteady cloud around airfoil [26] and propeller models [27].…”

Cloud Cavitating Flow That Surrounds a Vertical Hydrofoil Near the Free Surface

“…Cavitating flow is often examined through a water tunnel [3] or water tank test [4]. Computational fluid dynamics (CFD), which has been integrated into commercial software FLUENT and CFX [5][6][7] as well as into open-source [8][9][10][11] and in-house [12][13][14][15][16] software, has been recently introduced as a major approach for investigating cavitation. The cavitating flow of the unsteady cloud around the foil [17][18][19], propeller models [20], and other underwater vehicles [7,21] presents typical problems.…”