Magnetic Force Effect on an Airfoil CFD Simulation, ANSYS Fluent Training

Airfoil

We call the cross section of an airplane wing, wind turbine blade and helicopter, etc airfoil. Airfoils can have different geometries. We also use different airfoils to build an airplane wing. The proper choice of these airfoils for different applications depends on the aerodynamic properties of the airfoil. The following figure shows some examples of airfoils.

Magnetic Force Effect on an Airfoil Project Description

The present issue concerns the simulation of airflow around a NACA 0015 airfoil. This airfoil is a symmetrical airfoil that does not produce a lift force at zero attack angle, and we investigate the lift coefficient of this airfoil at different attack angles with and without magnetic (MHD) force. In this problem, we study the separation and the maximum angle of attack where the separation does not occur. By applying the magnetic force (MHD), the separation happens at the larger angle of attack.

Assumption

We use several assumptions for the present simulation:

• The simulation is Steady-State.
• The solver is Pressure-Base.

Geometry & Mesh of Airfoil

We design the present 2-D geometry by Design Modeler software. The coordinates of the airfoil points are imported in the software, and the solution domain is a circle of 10 to 12 times of the radius of the airfoil chord. To solve this problem, after defining the domain, an unstructured triangular mesh has been applied around the airfoil. For the boundary layer flow, applying finer meshing which departs from airfoil is gradually getting bigger in order to make it easier to solve and reduce the computational time.

CFD Simulation

Models (Magnetic Force Effect on an Airfoil)
k-epsilon	Viscous model
Standard	k-epsilon model
RNG	Standard Wall Function
off			Energy
Boundary conditions (Magnetic Force Effect on an Airfoil)
velocity inlet	Inlet type
27.45283226    m/s	x-velocity
3 9.992013787 m/s	y-velocity
wall			Walls type
No slip	Shear condition
Solution Methods (Magnetic Force Effect on an Airfoil)
Coupled			Pressure-velocity coupling
Satndard	pressure		Spatial discretization
First order upwind	momentum
Second order upwind	energy
Second order upwind	turbulent kinetic energy
Second order upwind	turbulent dissipation rate
Initialization (Magnetic Force Effect on an Airfoil)
Standard	Initialization method

Boundary Condition

A part of the middle of the solution domain, which is the airfoil, is specified and its wall is divided into two upper and lower portions by which the non-slip boundary wall condition is applied, in which the UDF magnetic force is applied (without using the MHD module) to the airfoil in the x-direction. The combination between the fluid flow field and the magnetic field is understood on the basis of two basic effects, including the induction of electric current due to the conduction of conductive material in a magnetic field, and the influence of the Lorentz force resulting from the interaction of the magnetic field and the electric current.

In this effect, the Lorentz force is investigated whose main relation is J = σ (E + U × B) which is used in the UDF to apply the magnetic field. The velocity inlet is applied to the input of the velocity inlet domain, where the input velocity is set as components and is defined in two components along the x and y directions.

Outputs

One of the aims of this problem is to observe the flow separation on the airfoil and its effect on the force and lift coefficient at different attack angles. To get the lift coefficient in the report definition section in the Force report menu, we activate the lift and we can extract the lift force for the upper and lower parts of the airfoil.

Reference Value

Since the purpose of the problem is to study the fluid behavior and lift force calculation only in the specific airflow space, we select the airflow around the airfoil as the reference zone.

Results & Discussions

We know that the plasma actuator works by creating an electric field between two electrodes. An electric field is formed and induces an electric or ionic wind near the surface by applying a large voltage difference between the electrodes. The induced flow acts as a physical force, moving the fluid near the electrodes to produce a jet with a net-zero velocity. This jet improves the flow profile in the boundary layer and delays separation. The purpose of plasma actuators is to control separation by reattaching the flow separated from the surface. This action can be done by accelerating the fluid near the wall inside the boundary layer.

Results & Discussions

In this project, velocity and pressure counters, streamlines, and velocity vectors are provided after applying the plasma actuator. As can be seen from the velocity contour, the plasma actuator’s application causes the flow in the boundary layer to accelerate and adhere to the surface of the airfoil. Also, the leading edge pressure suction has increased, and as a result, the lift has increased. As it turns out, after applying the plasma actuator, the flow separates from the surface of the airfoil somewhere before the initial separation point, which means that the separation is delayed. Therefore, it can be concluded that by applying a plasma actuator (MHD) to the NACA 0015 airfoil, a static stall occurs at a larger angle of attack.

You can obtain Geometry & Mesh file and a comprehensive Training Movie that presents how to solve the problem and extract all desired results.