Automotive Aerodynamics

Automotive aerodynamics is the study of the aerodynamics of road vehicles. Its main goals are reducing drag and wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds. Air is also considered a fluid in this case. For some classes of racing vehicles, it may also be important to produce downforce to improve traction and thus cornering abilities. 

Objectives - 

• Describe three factors important to the performance of a CO2-powered rocket car

• Calculate the area of a solid’s planar face

• Calculate the volume of a solid, and, when given the density, calculate the mass

• Create a new assembly

• Insert components

• Add mating relationships between components.

• Use Additive Manufacturing to build it and make it ready for racing.

Test car construction

Extruded a triangular shape to then subtract material to create the car body

                            Subtracted the cars body for maximum aerodynamics

Used the style spline tool and a half circle to make a cabin for the canister

created the back wheel well

created the front wheel rim which assist with aero dynamics

Inserted the canister circle into the body and cockpit

Filited all sharp surfaces to ensure maximum airflow over the body

                                             Added wheels and the canister to the cars body

Aerydynaimcs rap moddel for the car. The lighters the color the better the air flows over it. You can see big red spots in the wheel wells this is called dirty air.

Aerodynamic rap moddel for the car with 2 small wheels

This is a diagram that shows the air flowing over the car in a simulation. The arrows and different colors represent the different flows of air.

Online reasearch

I took a lot of inspiration from theese two designs but also added some of my own twist like some grates to allow for airlflow over the top of the boddy which assits with downforce as well as side wings and a spoiler on the back to clean dirty air.

Here is the first design

My second car design was more of a fun project and was not at all meant to win any of the races.

The horse and buggy was a fun design to challenge me here is my design. The Buggy design does not have any sepcial features since I wanted to keep it simple, although I did add an exhaust in the back for giggles

Horse + Buggy Creation

Buggy

Extruded the sketch of the body 

Made the body into a shell. This cuts out all of the inside filliment

Created the front window

Fillited all the surfaces

Created axel holes

Extruded the blast chamber for the C02 cartridge

Created a vent for air to flow through the inside of the buggy

Final buggy design

Horse

I first traced a sketch with the spline tool then extruded it

Created the connector from the horse to the buggy

Put bigger surfaces on the feet to create room for axel holes

Created axel holes

Final horse design

Assembly

Assembled all of the wheels and the C02 cartridge

Put a guidleine hole through entire assembly 

Final Asseembly design

Airflow sims

The purpose of the airflow sims is to use the solidworks airflow simulaters to determine the forces of lift and drag on the car. I did 2 diffrent simulations since the first one did not have the top vents and the second simulation added the factor of the top vents into the simulation equation to see the effect of the changes

Air flow sim version 1

Flow sim calculation chart

Flow sim graph

The colors show the effected mesh areas of the airflow while the arrows show the airflow themselves. You can see the masssive vortex in the back which need to the fixed.

Airflow Sim Version 2

You can see the improvement in the lift section on the second sim although their was no improvement in the drag area

Second flow sim graph

Second flow sim mesh tracking

You can see that the vents funnel the air below and overtop of the cart to make it more streamline and reduce the vertex in the back

Final drawing

Adative Manufacturing 

This is an image of my orignial slice. I had to remove the top so that I could axes the supports inside

With build plate supports only

The inside of the print

                                                                                              I printed the big wheels

slicer gif

Print Issue when creating the buggy and horse although I could keep the top and put it on the new horse and buggy

Newest print horse amd buggy plus the wheels

Final print with wheels on

Race Day

post processing

Race 1

Unfortunitly the horse did not finish its first race due to it weight so this is the only video that was retreived for this race

Since their is no time to print the horse and buggy any lighter I decided to use a larger canister size in the next races going from a 8 gram to a 12 gram canister

The velocity caluclations are a bit diffrent since the car did not finish, I used the max time of 5 to set the DNF time in the calculations

Race 2

Although this car did finish I want to add some grafite to the axels to add an extra lubricant to the axels which can make them turn better.

Velocity Calculations

Race 3

The third and final race I have progressivly increased time every single race

Look how big the C02 cloud is I bet the hole punctured is too big so too much C02 goes out at once I think if the puncture hole was smaller it would go faster since it would have more of a steady stream

The Third velocity test was very simular to the second veleocity test although their was a little bit of improvement

Final average velocity and standings

Second race day standings

Average total velocity this was greatly effected by the DNF time on day 1