Fluid-Structure Interaction over HAWT Turbine Vibration (one-way)

Description

In this project, we present a simulation of a Horizontal-Axis Water Turbine (HAWT) via ANSYS software.

Since the turbine blades are exposed to water flow, an interaction occurs between the water flowing and the turbine blades' structure. So, the water flow exerts a hydraulic force on the blades' body by hitting it. Therefore, we intend to perform a numerical simulation of the water turbine as a Fluid-Structure Interaction (called FSI).

The interaction between fluid and structure can be implemented as:

• One-way FSI

• Two-way FSI

In this project, we aim to analyze only the effect of fluid on the structure, and there is no need to account for the effect of the structure on the fluid. So, we choose One-way FSI, which is a simple and less-expensive approach.

We modeled the geometry via Design Modeler software. The computational domain is a sample space for water flow, in which a distinct fluid region is defined around the turbine body. The turbine is of the horizontal-axis type and includes three blades.

We meshed the computational domain via ANSYS Meshing software. The mesh is of an unstructured type, and approximately 3,400,000 cells have been generated.

Methodology

Fluid-structure interaction can be performed in two general methodologies:

• In the ANSYS Workbench environment, using an external solver

• Only in the Fluent solver (in the form of an intrinsic FSI).

For one-way FSI with an external solver, three main steps are required:

• Simulation of the fluid domain from the model using the Fluent solver

• Simulation of the solid domain from the model using the Transient Structural solver

• Transfer data directly from the fluid solver to the structural solver

Since we were analyzing one-way FSI and not considering the effect of structural displacement on the adjacent fluid, we didn't need to use the dynamic mesh model.

In addition, we used the Multiple Reference Frame (MRF) to define a rotational flow with a certain angular velocity in the region around the turbine body.

Results

We analyzed the results in two fluid and solid approaches:

In Fluent, we studied the behavior of water flow around the turbine. For this, we obtained the distributions of the pressure and velocity of water near the blades. The results show that the water flow collides with the rotating blades' body and, as a result, exerts a hydraulic force on the turbine structure.

In Structural Transient, we studied the behavior of the turbine blades' body under the influence of the applied forces of the water flow. For this, we obtained the distribution of the deformation, von Mises stress, and elastic strain. The results confirm that the water flow affects the turbine blades' structure.

In conclusion, we can claim that we carried out the simulation project of a HAWT correctly and acceptably by using the one-way FSI method.