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The Effect of Spoilers on Vehicle Aerodynamics and Performance

Description
An understanding of aerodynamics is crucial for automobile performance and efficiency. There are many types of “add-on” aerodynamic devices for cars including wings, splitters, and vortex generators. While these have been studied extensively, rear spoilers have not, and their effects are not as widely known. A Computational Fluid Dynamics (CFD)…

An understanding of aerodynamics is crucial for automobile performance and efficiency. There are many types of “add-on” aerodynamic devices for cars including wings, splitters, and vortex generators. While these have been studied extensively, rear spoilers have not, and their effects are not as widely known. A Computational Fluid Dynamics (CFD) and wind tunnel study was performed to study the effects of spoilers on vehicle aerodynamics and performance. Vehicle aerodynamics is geometry dependent, meaning what applies to one car may or may not apply on another. So, the Scion FRS was chosen as the test vehicle because it is has the “classic” sports car configuration with a long hood, short rear, and 2+2 passenger cabin while also being widely sold with a plethora of aftermarket aerodynamic modifications available. Due to computing and licensing restrictions, only a 2D CFD simulation was performed in ANSYS Fluent 19.1. A surface model of the centerline of the car was created in SolidWorks and imported into ANSYS, where the domain was created. A mesh convergence study was run to determine the optimum mesh size, and Realizable k-epsilon was the chosen physics model. The wind tunnel lacked equipment to record quantifiable data, so the wind tunnel was utilized for flow visualization on a 1/24 scale car model to compare with the CFD.

0° spoilers reduced the wake area behind the car, decreasing pressure drag but also decreasing underbody flow, causing a reduction in drag and downforce. Angled spoilers increased the wake area behind the car, increasing pressure drag but also increasing underbody flow, causing an increase in drag and downforce. Longer spoilers increased these effects compared to shorter spoilers, and short spoilers at different angles did not create significantly different effects. 0° spoilers would be best suited for cases that prioritize fuel economy or straight-line acceleration and speed due to the drag reduction, while angled spoilers would be best suited for cars requiring downforce. The angle and length of spoiler would depend on the downforce needed, which is dependent on the track.
ContributorsNie, Alexander (Author) / Wells, Valana (Thesis director) / Huang, Huei-Ping (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2019-12
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Elliptic Interface Reconstruction for Two-Phase Flow Problems Using the Volume of Fluid Method

Description

An interface reconstruction algorithm for the Volume of Fluid (VOF) method is required for two-phase flow problems for advection of phase interface. The primary method for interface reconstruction has been through piecewise linear interface calculation (PLIC) reconstruction. However, while PLIC reconstruction is highly accurate at representing small curvature interfaces by…

An interface reconstruction algorithm for the Volume of Fluid (VOF) method is required for two-phase flow problems for advection of phase interface. The primary method for interface reconstruction has been through piecewise linear interface calculation (PLIC) reconstruction. However, while PLIC reconstruction is highly accurate at representing small curvature interfaces by approximating planes across multiple grid cells, accuracy problems arise when the size of the mesh is too coarse to accurately approximate a large curvature without resorting to refining the mesh. An elliptic interface reconstructing algorithm is explored for two-phase flow problems in 2D to determine the viability of a higher-order interface reconstruction algorithm. This requires first developing an area overlap function between an arbitrary triangle and ellipse, which is then extended to calculate the area fraction field of an ellipse within a mesh. Then, the "reverse" problem of elliptic interface reconstruction given an area fraction field is examined. A study is conducted to determine the presence of any local minimums when varying the ellipse parameters. In the future, a multi-dimensional root-finding solver using Newton's Method will be developed to properly reconstruct the elliptic interface given the area fraction field.
ContributorsLee, Chase (Author) / Herrmann, Marcus (Thesis director) / Kasbaoui, Mohamed (Committee member) / Wells, Valana (Committee member) / Barrett, The Honors College (Contributor) / Mechanical and Aerospace Engineering Program (Contributor)
Created2022-05