Unsteady Double Wake Model for the Simulation of Stalled Airfoils

Abstract

In the present work, the recent developed Unsteady Double Wake Model, USDWM, is used to simulate separated flows past a wind turbine airfoil at high angles of attack. The solver is basically an unsteady two-dimensional panel method which uses the unsteady double wake technique to model flow separation and its dynamics. In this paper, the calculated integral forces have been successfully validated against wind tunnel measurements for the FFA-W3-211 airfoil. Furthermore, the computed highly unsteady flow field is analyzed in detail for a set of angles of attack ranging from light to deep stall conditions.

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…where ω is vorticity vector, u velocity vector, ν is kinematic viscosity, and ∇ 2 is Laplace's operator, respectively. A similar technique to model the unsteady wake is adopted by [11,12]. The conversion of doublet wake panel into an equivalent vorton is carried out by a similar approach as proposed by [11,12] to model the unsteady wake.…”

“…In the stall flutter case, the flow is dominated by separated flow, thus classical PM can be used here. However, for subsonic stall flutter a modified version of PM using viscous-inviscid coupling including discrete vortex particle (DVM) wake model can be employed for the separated flow problem [10][11][12] as it is in stall flutter. Moreover, the equivalent technique is also adopted for aeroelastic modeling of wind turbines [12][13][14], helicopter rotors, and aircraft aeroelasticity problems [10,15].…”

Simulations of the flow past a cylinder using an unsteady double wake model

“…The flow past the cylinder has been simulated for 80 seconds. The separation point at the surface of the cylinder, β s , is obtained from the experimental data of Schewe [5]. β s is fixed in the USDWM simulations to 80, 140 and 110 degrees for the subcritical, supercritical and transcritical cases respectively.…”

“…Following this idea, Ramos-García [2] developed a double wake model (DWM) and Marion [3] extended it to focus on the deep stall region. Later on, the model was modified to account for the dynamics of vortex shedding by Cayron [4] and Ramos-García [5]. In the present study the unsteady version of the solver is employed to simulate subcritical, supercritical and transcritical flows around a cylinder, with the aim to assess the capability of the flow solver to capture the changes in vortex shedding frequencies associated with the different flow states.…”

Simulation of the flow past a circular cylinder using an unsteady panel method

“…Following this idea, Ramos-García [2] developed a double wake model (DWM) and Marion [3] extended M A N U S C R I P T it to focus on the deep stall region. Later on, the model was modified to account for the dynamics of vortex shedding by Ramos-García et al [4].…”