Stanford Solar Car Project

The Stanford Solar Car Project is an entirely student-run, non-profit organization fueled by its members’ passion for environmentally sustainable technology. Every two years, the team designs, builds and races a solar car across the Australian Outback in the Bridgestone World Solar Challenge.

Challenge

In order to be successful in the World Solar Challenge, our solar car needs a fluid and sleek aerodynamic design. With the race set to start in the fall of 2021, our first priority is creating an aerodynamic body that can reduce drag and lift and promote smooth, laminar flow. Thus, this summer, as part of the aerodynamics team, I am tasked to create 1-2 iterations every week, specifically focusing on bullet style solar cars like the one shown above.

So far, I have created 8 iterations using the CAD software Siemens NX. Let’s take a look at a few of them!

Design Iterations

Iteration 1

My first iteration was a valiant effort at understanding this new CAD software. Although the software claims this model to be curvature continuous, it still lacks fluidity and seems as if the bubble, main foil, and fairing (top, middle, and bottom parts, respectively) were simply just glued together. But everyone starts somewhere!

Iteration 4

After a few iterations, I began to get a good feel for surfacing a solar car. From a design standpoint, this iteration has a fairly different approach from the first:

• The main foil has more of a curvature (a common theme for my future iterations) that reflects the nature of a bullet car

• The bubble is much more aerodynamic and realistic in terms of the shape

• The fairing is more smoothly integrated into the main foil, which improves its aerodynamics

• The top view shape of the car is more clean and sound

However, I ran into issues with surfacing that sharp vertical ending of the fairing. Despite its appearance, further analysis indicates that some of my surfaces around that tail end have intersected each other, an error that hurts the production-readiness of the car.

Iteration 6

With this iteration, I have decided to take a new route in designing the car:

• Instead of having the thin fairing end as mentioned in Iteration 4, this fairing overall is thicker (also to allow for the placement of the license plate in the back)

• The rounded nose of the car reflects the shape of a bullet

• This iteration is very smooth

An issue with this thicker fairing is that it hurts aerodynamic performance, since it is less of a streamline shape. While this is one of the “safer” models that I have made, there is still much more to experiment with the shape of the car.

Iteration 7

For iteration 7, I really tried to mask the drag that might be caused by the fairing and the bubble:

• The shape of the back end of the fairing is slimmer than before, but its shape is still somewhat preserved (because of the license plate)

• The bubble is now integrated into the leading edge/nose, which helps promote laminar flow

• The rounded bullet nose is preserved

There are still some glaring issues with this model. The construction of the nose is not smooth and some of the surface is not watertight, which hurts production-readiness. Additionally, the back end of the fairing can still be more slim while still leaving space for the license plate.

Meshing

CFD Results Over Time