Spoiler Angle Effect, Aerodynamic Analysis, Paper Numerical Validation, ANSYS Fluent Tutorial

Description

A rear spoiler is a device commonly used on vehicles to improve their aerodynamic performance. The main purpose of this study is to investigate the effect of changing the spoiler angle on the aerodynamic performance of a hatchback car.

The inlet boundary condition is a uniform flow with U = 40 m/s and a turbulence intensity of 0.2%. The corresponding Reynolds number (Re) based on the model’s height is 768,000.

In the case of the outlet boundary, the outlet pressure is applied at zero gauge pressure. The side and top walls of the domain are defined as symmetry boundary conditions. The ground and model surfaces are set as no-slip walls.

The computational domain looks like a rectangular box. Since the model is symmetric and the flow is steady, all simulations are performed for half of the flow domain with a plane of symmetry at the centerline location. The cross-sectional area of ​​the half-flow domain is 1738 mm × 1129.5 mm (height × width).

This study uses the RANS-based Computational Fluid Dynamics (CFD) method. To validate the project, obtained numerical results are compared with the data of the ‘Effect of spoiler angle on the aerodynamic performance of hatchback model’ paper.

The model is designed in the Design Modeler software, and then the meshing is done by ANSYS Meshing software. That is in a fully Polyhedra grid type that results in a 935,500 element number.

Methodology: Spoiler Angle Aerodynamic Effect

The turbulence model is the k-epsilon model with an improved wall, which is one of the useful two-equation models. Also, a fixed pressure-based solver is used to achieve steady state simulations.

Conclusion

The numerical results show that in the positive spoiler angle, the aerodynamic lift of the hatchback model is significantly reduced. However, when configured at a negative pitch angle, the Effect of the spoiler on lift reduction is inadequate. Although aerodynamic lift decreases by increasing spoiler angle, it was accompanied by a decrease in drag.

Finally, as seen in the charts above, the pressure coefficient parameter has acceptable accuracy compared to Fig-7 in the paper. Fig-7 is shown below: