Contra-Rotating Turbine CFD Simulation Training

Description

Contra-Rotating Turbine, Ansys Fluent CFD Simulation Training

The present simulation is about a contra-rotating VAWT turbine via ANSYS Fluent. The contra-rotating turbine is an axial flow turbine with two rows of blades, So these two rows of blades rotate with equal rotational speed but in opposite directions. Contra-rotating turbines recover energy and power loss due to airflow through the front row of blades.

In other words, using two rows of rotating blades in opposite directions doubles the turbine’s torque power.

In this simulation, the mesh motion method defines the rotational motion of air.

In this model, two rows of blades are designed. A distinct zone for airflow is defined in the vicinity of each of these rows. Then, for each of these two zones, mesh motion is used. The rotational velocity of both rows of blades is defined as 14.7 rad.s^-1; But these two areas’ central axis of rotation is defined in opposite directions.

The airflow around the upper blades rotates clockwise, and the lower row blades rotate counterclockwise. Also, the inlet airflow velocity to the computational domain is defined as 5.3 m.s^-1.

Geometry & Mesh

The present geometry is designed in a 3D model via Design Modeler. This model includes a rectangular cube computational domain with two rows of blades connected in parallel in the middle. Each row of blades has three blades.

The mesh of the present model has been done via ANSYS Meshing. Mesh is done unstructured, and the number of production cells is equal to 3747546.

Set-up & Solution

Assumptions used in this simulation  :

• pressure-based solver is used.
• The present simulation is steady.
• The effect of gravity is ignored.

 

Models
Viscous		k-epsilon
	k-epsilon model	standard
	Near-wall treatment	standard wall function
Boundary conditions
Inlet		Velocity Inlet
	velocity magnitude	5.3 m.s-1
Up & Down Blades		Wall
	wall motion	stationary wall
Outlet		Pressure Outlet
	gauge pressure	0 pascal
Symmetry		Symmetry
Methods
Pressure-Velocity Coupling		SIMPLE
	pressure	Second-order
	momentum	First-order upwind
	turbulent kinetic energy	First-order upwind
	turbulent dissipation rate	First-order upwind
Initialization
Initialization methods		standard
	gauge pressure	0 pascal
	x-velocity	5.3 m.s-1
	y-velocity & z-velocity	0 m.s-1

Contra-Rotating Turbine Results

After simulation, streamlines and 2D contours related to velocity, pressure, and velocity and pressure gradients are obtained. The contours show that pressure and velocity in the space between the two rows of turbine blades increase, and, as a result, the value of torque and power applied to the turbine blades is enhanced.

Also, the value of torque applied to the upper blades (clockwise) is equal to 1.89 N.m, and the value of torque applied to the lower blades (counterclockwise) is equal to 1.93 N.m. Therefore, in this turbine model, approximately equal torque is applied to each row of blades.