Numerical Investigation of Flow Control Feasibility with a Trailing Edge Flap

W J Zhu,W Z Shen,J N Sørensen

doi:10.1088/1742-6596/524/1/012102

Abstract

This paper concerns a numerical study of employing an adaptive trailing edge flap to control the lift of an airfoil subject to unsteady inflow conditions. The periodically varying inflow is generated by two oscillating airfoils, which are located upstream of the controlled airfoil. To establish the control system, a standard PID controller is implemented in a finite volume based incompressible flow solver. An immersed boundary method is applied to treat the problem of simulating a deformable airfoil trailing edge. The flow field is solved using a 2D Reynolds averaged Navier-Stokes finite volume solver. In order to more accurately simulate wall bounded flows around the immersed boundary, a modified boundary condition is introduced in the k- ω turbulence model. As an example, turbulent flow over a NACA 64418 airfoil with a deformable trailing edge is investigated. Results from numerical simulations are convincing and may give some highlights for practical implementations of trailing edge flap to a wind turbine rotor blade

Highlights

Today, there exists many different ways of controlling airfoil characteristics using e.g. injection of fluid in the boundary layer, plasma actuators or deformable airfoil shapes
This paper concerns a numerical study of employing an adaptive trailing edge flap to control the lift of an airfoil subject to unsteady inflow conditions
For controlling the flow about wind turbine blades, the main focus has been on the use of Trailing Edge Flaps (TEF)

Summary

Introduction

There exists many different ways of controlling airfoil characteristics using e.g. injection of fluid in the boundary layer, plasma actuators or deformable airfoil shapes. While practical design of large wind turbine rotors with flaps is still under investigation, numerical and experimental studies can be done for 2D airfoil sections equipped with TEF devices. A viscous-inviscid interaction technique [13] developed at DTU has shown good accuracy of modelling flows for airfoils equipped with deformable trailing edges. The hybrid IB technique has the advantage of solving flow over partially moving boundaries, such as an airfoil with a deformable TE By using this method the flow around the main fixed part of the airfoil is solved in a standard finite volume way, whereas the moving trailingedge flap is simulated on a curvilinear mesh using the standard IB method.

Numerical method

Geometrical setup

Results and discussions

Conclusions