Physik | Technik
Gian Luca Ratschiller, 2007 | Thörishaus, BE
Giulio Schileo, 2006 | Toffen, BE
The goal of this project was to electrify a racing kart and optimize its aerodynamics. To achieve this, a custom self-built powertrain was designed and integrated. The choice was made to run a permanent magnet synchronous motor fed by a LiPo powerpack. Aerodynamic improvements were made to lower the drag coefficient and increase the downforce significantly. The aerodynamic development was made using the CFD-Software OpenFOAM. A model of the bodywork was then optimized and then further improved until a final design was reached. Some of the body panels were then manufactured using composite lamination techniques. After all parts were integrated into a generic kart chassis, the vehicle was tested on the DTC-test track in Vauffelin, BE. Despite our budget and time restrictions, the test day proved to be successful, impressing with the fast acceleration (0-100km/h in 4s), high aerodynamic efficiency, as well as great potential for improvement.
Introduction
Our project was aimed at constructing an electric kart based on an existing chassis. In our build, we decided against using any pre-assembled electric drive kit, instead opting to develop a custom, higher-power solution. In addition to the powertrain swap, we wanted to improve the kart’s aerodynamics by designing and manufacturing an optimized aero-package. Our concrete goals were to achieve a 0-100km/h acceleration of under 5 seconds and to achieve a low drag coefficient of 0.4 to 0.7 while keeping the downforce at a minimum of 500N.
Methods
Both the electrical system and the aerodynamic concepts experienced a first preliminary design phase, in which the electrical schemes were created in KiCAD, simulated in LTSpice, and then through calculations, a basic component list was created. The components were then ordered and tested individually. The integration phase was helped by a CAN Network interpreter software through which the correct commands were implemented on the onboard computer. The aero-development started with concept simulations in SolidWorks, after which the geometry was set up in CAESES. A OpenFOAM setup was adjusted to our use case and then connected to CAESES. First, a design exploration for eliminating parameters with a small impact was launched. Then, a genetic optimization loop (NSGA-II) was started. The resulting model was then manually adjusted and improved further, culminating in the final design. Shortly afterwards, manufacturing of the molds for composite manufacturing began. During this period, more and more of the electrical components arrived, had their functionality tested and were then integrated into the chassis. The last step was laminating the three parts of the bodywork panels, which were then trimmed to their final shape and then installed into the chassis.
Results
To assess the performance of the vehicle, high-power tests were carried out at the Dynamic Testing Center in Vauffelin. The testing conditions were acceptable, with a dry track though low surface and outside temperature. Following our safety concept, we decided not to surpass 130 km/h and run all tests with what turned out to be 1/4 maximum power. Acceleration as well as efficiency and cornering performance were evaluated. With an acceleration time from standstill to 100km/h of 4 seconds, cornering acceleration of 2G, and a measured drag coefficient of about 0.37, we deemed the results to be more than satisfactory.
Discussion
While we were more than satisfied by our results, some discoveries impressed us even further. All high-power testing should have been carried out at 1/3 maximum power, but due to a configuration issue with the current sensor, the actual power was lower. Another curious fact was the low drag coefficient, which was nearly on par with the simulations but missing the rear bodywork. This could be caused by inaccurate CFD-Simulations, as neither a mesh study nor any other correlation test was done.
Conclusions
After careful analysis of the administrative organization of the project and the performance results, some shortcomings proved apparent. For example, an overcurrent error during the test led to our motor shutting off mid-run. Such problems were retrospectively fixed after an updated software. On the aerodynamic side, the optimization task technically failed, as the needed generation count could not be reached in time. Also, some of the mounting systems of the aero-surfaces to the chassis were improvised due to the lack of time and resources, which needed to be redesigned. All in all, we consider the results of our project to be extremely satisfactory and the experience we gained from it to be invaluable.
Würdigung durch den Experten
Leon Hinderling
Gian Luca Ratschiller and Giulio Schileo have undertaken a rigorous exploration of the performance limits of go-karting. Their research employs industry-grade electronics and advanced aerodynamic optimization methodologies to improve a regular go-kart. Notably, their optimized vehicle achieves an acceleration of 0–100 km/h in just four seconds, surpassing the performance of most road vehicles. Given the risks associated with high-speed systems, I strongly recommend prioritizing the security of the system.
Prädikat:
hervorragend
Sonderpreis «Summer School of Science» gestiftet von der Metrohm Stiftung
Gymnasium Köniz-Lerbermatt
Lehrer: Florian Neuling