Gas Turbine, Thermal FSI, ANSYS Fluent CFD Simulation

Description

In this project, we present a simulation of a Gas Turbine Blade under Thermal FSI via ANSYS Fluent software. We have modeled a single blade from one of the stages of a gas turbine, which contains an internal channel with fine holes for the cooling process. The computational domain consists of a fluid zone dedicated to the streams and a solid region as the pipe body surrounding the fluid zone.

What is FSI?

Air flows throughout the turbine blade construction and through its holes. So, the fluid flow can expose a pressure load on the inner wall of the T-junction pipe. In such a condition, analysis of Fluid-Structure Interaction (FSI) becomes important. It means that both fluid and structural calculations are available.

Why Thermal FSI?

The cooling airflow inside the turbine's internal channel is in contact with the hot body of the turbine blade. So, it is expected that a thermal load will be imposed on the solid body. As a result, the focus is on the Thermal FSI. It means the solution data of fluid flow, structural, and thermal calculations are coupled.

1-way or 2-way?

Only the effect of the pressure and thermal loads of the flow on the inner wall of the turbine blade is analyzed; no need to consider the effect of the solid blade structure on the nearby flow. Hence, it is called One-way FSI.

Methodology

For FSI simulations, we recommend two general methods: intrinsic FSI and extrinsic FSI. If the calculation of both the fluid and the structure is performed only in ANSYS Fluent, it is called Intrinsic FSI. Meanwhile, if the calculation process of the fluid and the structure is performed in different and individual solvers and then coupled with each other, it is referred to as Extrinsic FSI.

Intrinsic FSI:

In this project, we have used the intrinsic FSI method. We performed fluid and solid analyses for both the fluid and structural domains, using only the ANSYS Fluent solver. It means that no external solver is required for the interaction between the fluid and the structure.

Structure Model:

For the internal FSI, we have used the Structure model. By this option, the calculations for solids are also added to fluids.

Linear or Non-linear Elasticity?

We used the Linear Elasticity method for structural analysis. It means that the deformation or displacement of the structure is proportional to the force value exerted by the fluid.

Thermal Effect:

Since we intend to analyze the thermal load in addition to the overall pressure load, we enable the Thermal Effect option.

Conclusion

We have investigated the results by analyzing the interaction between fluid and solid.

Structural:

We obtained the contours related to the distribution of the total displacement and von Mises stress on the inner wall of the turbine blade (interface between fluid and solid zones), which is exposed to the cooling flow.

The results confirm that the maximum deformation and stress are concentrated in the upper zones of the blade, because the fixed support is defined on the central turbine body. In addition, since the upper regions of the gas turbine blade are exposed to the minimum values of the internal cooling process, the highest thermal stress may appear.