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Project Summary: I worked on a team of four with the goal of this project being to design a car with maximum downforce while minimizing drag. We used Solidworks Flow Simulation to test our designs.
Project Summary: I worked on a team of four with the goal of this project being to design a car with maximum downforce while minimizing drag. We used Solidworks Flow Simulation to test our designs.
Constraints (Limitations and Requirements):
Constraints (Limitations and Requirements):
Dimensional Constraints:
Wheelbase: 104.3 inches
Width at the Tires: 80 inches
Maximum Length: 185 inches
Maximum Height: 45 inches
Passenger Compartment: 50 inches wide, 35 inches long, 35 inches tall
Engine Block Dimensions: 40 inches long, 25 inches tall, 30 inches wide
Engine Placement: Behind the passenger compartment, neither compartment may be angled
Passenger compartment must not extend beyond the front tire center line
Criteria (Goals to be Achieved):
Maximize Aerodynamic Downforce: Design the car to maximize downforce while adhering to specified dimensions and performance metrics.
Minimize Drag Force: Maintain a drag force at 150 mph (67.056 m/s) no greater than 950 lbs. (4240 N), comparable to the Nissan IMSA GTP car.
Efficient Fuel Pump Sizing: Accurately size a fuel pump that can supply the required fuel flow rate to the engine at 60 psi, considering the motor's horsepower requirement at 200 mph.
Physical Constraints:
Vehicle must have four cylindrical tires: Each 28 inches in diameter and 12 inches wide
No part of the car’s body may be closer than 4 inches to the ground except the tires
When viewed from the front, tires must be placed at the edge of the vehicle’s width and all 4 tires must touch the ground
Simulation Constraints:
Computational Domain: Extends 1 car length in front, 2 behind, 1 car width on each side, and 1 car width above the vehicle
Include a ground plane and ensure the computational domain cuts into the ground plane
Run the simulation at a mesh setting of 4
Design Inspiration: GTP Race Cars from the 80s
Design Inspiration: GTP Race Cars from the 80s
1984-1987 Porsche 962c
1984-1987 Porsche 962c
L/D: 4.40:1
1989 Nissan GTP ZX-Turbo
1989 Nissan GTP ZX-Turbo
L/D: 4.60:1
Design Approaches
Design Approaches
Design: Kevin's Car
Speed: 150 mph
Lift Force: -2,546.478 N
Drag Force: 2,820.548 N
L/D Ratio: -0.903
Design: Jadin's Car
Speed: 150 mph
Lift: -7,157.657 N
Drag Force: 1,430.651 N
L/D Ratio: -5.003
Design: Jordan's Car
Speed: 150 mph
Lift: -17,552.633 N
Drag Force: 3,317.451 N
L/D Ratio: -5.291
We first approached the project by doing all of our own designs for the first couple weeks. We would then come together and work on the initial design that had the highest lift-to-drag ratio.
Final Design
Final Design
Final Numbers
Final Numbers
Speed: 150 mph
Lift: -17,772.533 N
Drag Force: 3,186.32 N
L/D Ratio: -5.578
Pressure Distribution
Pressure Distribution
Increased pressure on the front lip of the car causing some air to stagnate
Low pressure at the start of the underbody/diffuser as well as at the wheels
The cambered wheels is what separated our group from the rest to be the top performing car in the class. We saw there was a loop hole and decided to make the wheels cambered at an angle of 20 degrees. This car could never travel at 150 mph with wheels like that but theoretically if it could, the downforce would be much greater.
The wheels at an angle reduces the cross-sectional area and therefore reduces the amount of air stagnating. The wheels also act almost as miniature Venturi tubes which compresses and then allows the air to expand into the main venturi under the car. This can be clearly seen where you see a pressure drop.
While the wheels gave us that extra push, the underbody is what allowed for most of the downforce to be generated. The underbody acts as a larger Venturi tube.
Flow Trajectories
Flow Trajectories
With the location of the the driver's cabin and engine block, we wanted the car to have the least amount of stagnating air on that front but also have a tall enough car to allow for the underbody to come as high as it does here.
Flow trajectories allow use to sport where air might be stagnating to cause pressure drag and where it was separating off of the car which would cause viscous drag.
One of the biggest challenges was creating an underbody that expands the air at a rate that doesn't allow the air to separate into a low pressure zone and cause a vacuum behind the car.
Vorticity Plots
Vorticity Plots
The vorticity plots presented above provide a visual representation of the airflow characteristics along the vehicle, distinguishing between laminar and turbulent regions. These plots measure the intensity of rotational flows, or vorticity, around the car, highlighting areas where turbulence is more pronounced. While turbulence typically suggests chaotic air movement, it can also facilitate the formation of beneficial vortices. These vortices harness kinetic energy from the laminar air to minimize flow separation, thus enhancing aerodynamic efficiency. However, not all turbulence is advantageous; in some areas, it may lead to increased drag by causing the airflow to decelerate and detach from the vehicle's surface.
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