VTOL UAV FSI Analysis: CFD Simulation by Ansys Fluent

Description

FSI Analysis: VTOL UAV CFD Simulation Training

Introduction

FSI simulation involves the interaction between the fluid and the structure. If we only want to consider the effects of the fluid on the structure, we use one-way method, and if we want to consider the effect of the structure on the fluid in addition to the effect of the fluid on the structure, we use two-way method. In this simulation, we have performed a two-way simulation. Previously, we could only run the two-way method in Workbench, but now Fluent software also has this capability. However, if our simulation involves large displacements, it is better to use Workbench because Fluent is not able to accurately analyze large displacements.

A VTOL (Vertical Take‑Off and Landing) UAV is a type of unmanned aircraft that can lift off and land like a helicopter, yet during flight benefits from horizontal flight and usually fixed wings.
This combination provides two advantages at once: operational flexibility in confined spaces (without needing a runway) and long range and endurance similar to fixed‑wing aircraft.

Hybrid VTOL drones typically combine multiple vertical propellers (for takeoff and landing) with one or more fixed wings (for cruise flight).
In the first phase, the drone takes off vertically; after reaching a suitable altitude, it gradually transitions to horizontal flight, and the propellers or main motors are directed forward to increase aerodynamic efficiency.

The geometry of the present model is three-dimensional and has been designed using SpaceClaim software. We do the meshing of the present model with Ansys Meshing software. The mesh type is Tetrahedral, and the element number is 2,659,245.

Methodology

In this FSI study used a steady-state, pressure-based CFD simulation in ANSYS Fluent software to analyze the incompressible flow around a UAV and the fluid-structure interactions(FSI). The flow physics was modeled using the k-ω SST turbulence model and a dynamic mesh was also used.

Results and Conclusion

According to the extracted contours, it is observed that, as expected, the greatest displacement occurs at the wing tips of the UAV and the greatest stress is at the wing-body connection.

It is also seen in the diagrams that the amount of displacement decreases from the wingtips to the fuselage junction and reaches zero at the fuselage. Although the fuselage displacement may sometimes not be zero, its amount is very small and is usually ignored. The two diagrams below are for the front and rear airfoils.