{"id":805,"date":"2023-05-17T21:08:57","date_gmt":"2023-05-17T21:08:57","guid":{"rendered":"https:\/\/www.viliamkacerik.com\/?p=805"},"modified":"2023-06-21T10:42:10","modified_gmt":"2023-06-21T10:42:10","slug":"bachelor-thesis-complete-1","status":"publish","type":"post","link":"https:\/\/www.viliamkacerik.com\/index.php\/2023\/05\/17\/bachelor-thesis-complete-1\/","title":{"rendered":"Bachelor Thesis Complete! – Design of Ground Effect for UCL Formula Student Racing"},"content":{"rendered":"\n

As of writing this post, my bachelor thesis has been submitted and presentation successfully defended. The official title of the thesis was: “Design and Development of Ground-Effect Aerodynamics for the 2023 UCL Formula Student Racing Car”. This post is a summary of my bachelor thesis. <\/p>\n\n\n\n

This project consisted of benchmarking the baseline performance, developing the design in a concept and detailed design stage, and wind-tunnel testing of a scaled-down model in UCL Mechanical Engineering\u2019s wind tunnel facility. The delivery of this project was completed under a unique design methodology and new tools for design tracking and decision-making (called the Design Map). The choice to develop ground effect aerodynamics, rather than front & rear wings, was a strategic decision in line with UCL Racing\u2019s design philosophy which focuses on developing a compact, short and narrow vehicle to prioritise the vehicle\u2019s driveability and minimise the chances of hitting cones.<\/p>\n\n\n\n

\"\"
Unique Design Methodology<\/figcaption><\/figure>\n\n\n\n

Brief motivation<\/h2>\n\n\n\n

Litterature review suggests that implementing a full aerodynamic package can reduce the laptime of a Formula Student racing vehicle by up to 5%. For UCLR, this would mean +30 points in the competition, enough to claim 5th place overall rather than 6th. The primary performance diagnostics were determined to be the lift coefficient and aerodynamic balance. Using a laptime simulation software, it was determined that a 10% change in lift coefficient leads to a 90 ms\/lap difference, whereas a 10% change in drag coefficient leads to a 30 ms\/lap difference. This was in line with the litterature review which suggests that designers of Formula Student racing cars should focus on maximising downforce, rather than minimising drag. Therefore, this project aims to design and develop ground effect aerodynamics that will maximise downforce. Success criteria:<\/p>\n\n\n\n

    \n
  • Simulated laptime reduction must be at least 0.5 seconds (considered as minimum gain for the project to be considered a worthy investment).<\/li>\n\n\n\n
  • The aerodynamic balance must be between 40% and 45%<\/li>\n<\/ul>\n\n\n\n
    \"\"
    Aerodynamic diagnostics <\/figcaption><\/figure>\n\n\n\n

    Baseline of 2023 vehicle <\/h2>\n\n\n\n

    CFD was used to assess the aerodynamic performance of the 2023 baseline vehicle without any aerodynamic package. In the pre-processing stage, the geometry was simplified from the “manufacturing” CAD model, to a CFD-ready model. The vehicle was simulated as travelling in a straight line at 15 m\/s (average velocity around FSUK endurance track), with wheels rotating and only one half of the vehicle was simulated to save on computational cost. <\/p>\n\n\n\n

    \n
    \"\"
    Manufacturing model<\/figcaption><\/figure>\n\n\n\n
    \"\"
    CFD-ready model<\/figcaption><\/figure>\n<\/figure>\n\n\n\n

    The processing of the simulation was a done by the k-omega SST (RANS) solver with a wall turbulence model as it had proven to be the most effective solver for simulating highly turbulent Ahmed Bodies. In this case, the Reynold’s number was 2.6 million. In post-processing, different parts of the vehicle were analysed to determine their contributions to the lift and drag. <\/p>\n\n\n\n

    \"\"
    Contribution of various parts to lift and drag forces.<\/figcaption><\/figure>\n\n\n\n

    In addition, a mesh indepence of individual parts was carried out in order to determine the necessary amount of refinment of every part: <\/p>\n\n\n\n

    \"\"
    Mesh convergence <\/figcaption><\/figure>\n\n\n\n

    Concept and Detailed Design Stage<\/h2>\n\n\n\n

    The design was developed using a novel design method. The concepts were developed by an iterative process, where only one design change for each model, and monitored thanks to a “Design Map” tool – this gave a clear indication on whether the design change increased or reduced performance. This details the primary aerodynamic diagnostics, chosen to be the lift coefficient (CL) and aerodynamic balance (AB), were used to assess the performance. <\/p>\n\n\n

    \n
    \"\"
    Design Map Tool used for tracking design iterations and design decision making <\/figcaption><\/figure><\/div>\n\n\n

    The final model was obtained in the detailed design stage, where the dowforce was first maximised by fine-tuning the angle of the rear diffuser. Secondly, the targetted aerodynamic balance was achieving by adding a pair of front winglets (shown in orange below): <\/p>\n\n\n\n

    \"\"
    Evolution of the design throughout concept stage and detailed design stage<\/figcaption><\/figure>\n\n\n\n

    It is also worth noting that the addition of the winglets does not increase the turning radius of the vehicle, and therefore is compatible with the philosphy of the vehicle. <\/p>\n\n\n\n

    \n
    \n
    \"\"
    Front winglet does not compromise turning radius.<\/figcaption><\/figure>\n<\/div>\n\n\n\n
    \n
    \"\"
    Technical details of the final model<\/figcaption><\/figure>\n<\/div>\n<\/div>\n\n\n\n

    The pressure contour of the underside of the vehicle displays regions of very low pressure, which demonstrates that the ground effect occurs as desired. <\/p>\n\n\n\n

    \"\"
    Pressure contour of the underside of the vehicle.<\/figcaption><\/figure>\n\n\n\n

    Wind Tunnel Experimental Testing<\/h2>\n\n\n\n

    A wind tunnel testing rig was designed, manufactured and assembled. Red pieces of string (tufts) were glued onto the vehicle to allow for a visual analysis of the fluid flow around the vehicle. <\/p>\n\n\n\n

    \n
    \n
    \"\"<\/figure>\n<\/div>\n\n\n\n
    \n
    \"\"<\/figure>\n<\/div>\n<\/div>\n\n\n\n

    The tufts allow for a qualitative comparison between the wind tunnel and CFD case: <\/p>\n\n\n\n

    \n
    \n