Revise & Rewrite Engineer Report

Car Design Approach

The final design got optimized with the identified challenges and opportunities using a parametric design process. Initially, there was a comprehensive assessment to determine core factors in most of the professionally designed racecars whose performance was extraordinary. SolidWorks then got developed as the general shape where features got added systematically and optimized, leading to ever improving iterations. A flow simulation got performed after each design change so as examine the effect on the lift to drag ratio. The results then got recorded. The performance results and images from the iteration progression get included in Appendix A and enable the visualization of the parametric process.

The overall shape of the car got optimized as the first component of the car. The body of the car got designed to streamline air over the surface by minimizing the frontal area. This phase initially got implemented at iteration 9 and later enhanced at iteration 34. The removal of sharp bends through the use of fillets got implemented at iteration 13, and a tear drop design to passenger compartment got implemented at iteration 34. The outcome of these modifications was less pressure drug, as air flows around the streamlined shape become more easily. All the features incorporated in the design minimized drag and at the same time improved the downforce to drag ratio. This concept for the streamlining got derived from a combination of high-performance racecars from Grand Prix racing series and Formula 1.

At iteration which was the half way stage of the design process the diffuser got optimized in the bottom of the surface of the car. The large cavity made the flow of air underneath the car accelerates thus forming an area of low pressure. The desired downforce eventually got created due to the pressure difference between the bottom and top surfaces.

The modification of the rear spoiler was another core feature designed to increase workforce on the car. Due to the upward angle of the spoiler that directs the streamlined flow of air upward, there is a resultant force downward and a high-pressure region created on the top surface of the car. The rear spoiler got built into the body of the car instead of getting elevated from the surface of the body of the car so that shear drag would get reduced around the spoiler. Although the spoiler has existed from iteration 1, its improvements have taken place in all the iterations of the entire process.

Several design iterations had got completed when a minor setback in the design of the car occurred. The designers discovered that the wheels of the car could no longer fit into the design constraints since they were semi-circles instead of full cylinders. This error occurred when the body of the car was getting trimmed and also when the top of the wheels got cut accidentally. The correction of this error took place in iteration 24.

Performance Outcomes

The performance outcomes of the designed car got based on the data acquired from the SolidWorks Flow Simulation 2014. For all the iterations, the flow simulation got to run with a computational domain of one car length in front, two car lengths behind, one car width on either side, one car width above the vehicle and a plane underneath the car that served as the ground. Hence, there was a complete representation of airflow around the car and consistency on each iteration. All the simulations got to run at a mesh setting of 4 and the turbulence parameters got used by default.

Figure 10 illustrates the Velocity versus Drag and Lift Coefficients. The comparison between lift/drag coefficients and vehicle velocity got done using the vehicle frontal area. The figure also explains the abrupt increase of downforce coefficient (negative lift coefficient) and decrease in drag. After the flow gets transitioned, the lift and drag forces become nearly constant.

Figure 11 illustrates the Reynolds Number vs. Lift and Drag Coefficients. It is a comparison between the rise of Reynolds number to lift and drag coefficients with air at 20o [C]. The comparison gets illustrated that there is a drastic change in both the lift and drag coefficients when the Reynolds numbers jump from 2 million (likely laminar) to 4.5 million (likely turbulent). It, therefore, demonstrates the drastic effect that fluid characteristics have on aerodynamics. Once the flow has transitioned, the lift and drag coefficients become nearly constant.

Figure 12 illustrates the Air Velocity vs. Lift to Drag Ratio.  It undertakes a comparison between vehicle speed and lift to drag ratio.  There is an assumption that the vehicle velocity increases from less than 20 mph to 30 mph and the flow characteristics change from laminar to turbulent; hence, resulting in an increase in the drastic lift to drag ratio. When the flow has transitioned, the lift to drag ratio becomes nearly constant.

Figure 13 illustrates Velocity vs. Required Power. It is a comparison between vehicle velocity and the required power to overcome the force of drag. It demonstrates the exponential relationship between vehicle velocity and horsepower needed.

Figure 14 illustrates the Pressure Distribution Along Bottom of Aerocar. It is a visual of the pressure distribution along the bottom of our Aerocar. The highest low-pressure area is at the beginning of the diffuser (large blue area near the center of the car).

Figure 15 illustrates the Pressure Distribution At Rear of Aerocar. It represents a visual display of the pressure distribution at the rear of the Aerocar. The low, as well as the higher pressure formed by the diffuser under the Aerocar clearly, gets seen. These high and low-pressure zones get established due to high and low velocities of the air flowing around the Aerocar. The air going under the car gets forced to accelerate to a higher velocity, creating a lower pressure, and the inverse effect occurs above the Aerocar. This high-pressure concentration at the rear of the car reduced drag and improved the overall downforce to drag ratio.

Figure 16 illustrates the pressure distribution at the front of Aerocar. It is a visual representation of the pressure distribution at the front of the Aerocar. A high-pressure zone gets viewed at the front of the Aerocar and cannot get avoided. A low-pressure zone gets created at the center hump of the vehicle. This pressure zone is undesirable and cannot get avoided since a passenger compartment must get incorporated into the car.

Figure 17 illustrates an air velocity plot longitudinal along the center line of the car. If an object moves through a fluid at a set velocity, the fluid will slow when it encounters the object. It demonstrates the reduction in velocity when it comes into contact with the object.

Conclusions

The incorporation of aerodynamic intuition and diligent, parametric design led to the development of the final Aerocar design. It is essential for students pursuing engineering major to combine these strict engineering principles and the artistic creativity necessary for the innovatively streamlining of the Aerocar. After a critical study on racecar designs from F1 and Grand Prix racing series, the Aerocar got optimized through parametric design. The final concepts implemented in the car design to enhance the downforce are a teardrop shaped drivers’ compartment, rear spoiler, diffuser, and general streamlining.

The lessons acquired from the research include a better understanding of racecar aerodynamics at a core level. The interaction of various dimensions of a car’s design enhanced the understanding of a car such as ride height, sharp edge reduction, diffuser affects, and channeling turbulence. It also changed the team’s perspective of automobiles and boosted our confidence to design other external flow applications. The use of the theory learned in classes in this project enabled learners to have a well-rounded understanding of aerodynamics and external flow. The project recommends that the utilization of an elevated spoiler and additional variations to the diffuser (including the use of two channels instead of just one) to further improve the downforce to drag ratio of the Aerocar.

Sherry Roberts is the author of this paper. A senior editor at MeldaResearch.Com in research paper writing help 24 hours if you need a similar paper you can place your order for essay writing services.