A Body with Active Aerodynamics for a D-I-S Race Car

Cieplak, Damian Krzysztof

4. term

Electro-Mechanical System Design, Master

2023

60

This thesis presents the design and evaluation of a vehicle body with active aerodynamics for a DIS1 race car, with a primary focus on an active rear wing and its support brackets and actuation. The aim is to integrate electromechanical system design into aerodynamic components and demonstrate multidisciplinary work. The project was carried out with D‑I‑S, which provided the car model and data used for design and evaluation. Aerodynamics strongly influence performance, but there is often a trade-off between low drag and high downforce (the downward force that increases grip). Active aerodynamics can change geometry while driving to balance these needs with fewer compromises. Each design stage is supported by relevant simulations and/or calculations to verify expected performance. The process begins with the car body, shaped for low drag and smooth airflow so that later-added active aero elements are affected as little as possible. The body went through two iterations until a satisfactory result was reached. The rear wing was then sized to generate enough downforce for the car to handle at least the lateral acceleration likely achieved by the current Nürburgring lap record holder at the compression in the Foxhole section. As part of the wing design, simulations using a NACA 4412 airfoil (a standard wing profile) were run to relate lift and drag coefficients to angle of attack. The resulting aerodynamic coefficients differed from initial estimates, prompting a redesign of the wing. A “Scorpion Tail” wing bracket was devised to support the wing and selected after structural and aerodynamic simulations comparing it with swan-neck and reverse swan-neck mounts. The rear wing is actuated by a servo motor, flexible shaft, and worm drive that turn the shaft coupled to the wing. This solution is considered better suited than conventional approaches for this application because it is compact, lightweight, and adaptable to the geometry. A simple control concept is proposed: steering wheel angle and vehicle speed as inputs, suspension compression to compute the error to be corrected, and servo motor position as the output. Benchmarking yields optimistic indications that DIS’s targets are achievable. Some simulations show negative drag on the rear wing; this is likely related to the car’s downward-curving rear and/or simulation settings, but the exact cause remains unidentified. Overall, within the defined project scope, the design and evaluation of the car body with active aerodynamics are considered complete.

Denne afhandling beskriver design og evaluering af en bilkrop med aktiv aerodynamik til en DIS1-racer, med hovedfokus på en aktiv bagvinge samt tilhørende vingeophæng og aktuering. Formålet er at integrere elektromekanisk systemdesign i aerodynamiske komponenter og demonstrere tværfaglighed. Projektet er udført i samarbejde med D‑I‑S, som har leveret bilmodel og data til design og evaluering. Aerodynamik påvirker i høj grad bilens ydeevne, men der er ofte et kompromis mellem lav luftmodstand (drag) og høj nedadrettet kraft (downforce), der øger vejgrebet. Aktiv aerodynamik kan skifte geometri under kørsel og dermed forbedre balancen med færre kompromiser. Hvert designtrin er ledsaget af relevante simuleringer og/eller beregninger for at sikre den forventede ydelse. Arbejdet starter med bilkroppen, som formes med lav luftmodstand og så ren strømning som muligt, så senere tilføjede aktive aeroelementer påvirkes minimalt. Karrosseriet gennemgik to iterationer, indtil et tilfredsstillende resultat blev opnået. Derefter dimensioneres bagvingen til at skabe nok downforce til, at bilen kan håndtere mindst samme laterale acceleration som Nürburgrings nuværende omgangsrekordholder sandsynligvis nåede ved kompressionen i Foxhole-svinget. Som del af vingeudviklingen gennemføres simuleringer af en NACA 4412-profil (en standard vingeprofil) for at fastlægge sammenhængen mellem løfte- og modstandskoefficienter og angrebsvinkel. De fundne aerodynamiske koefficienter afveg fra de indledende antagelser og førte til en redesign af vingen. Et "Scorpion Tail" vingeophæng udvikles til at bære vingen; det blev valgt efter strukturelle og aerodynamiske simuleringer, hvor det blev sammenlignet med svanehals- og omvendt svanehals-ophæng. Aktueringen af bagvingen sker via en servomotor, en fleksibel aksel og et snekkegear, som driver akslen mekanisk koblet til vingen. Denne løsning vurderes mere velegnet end konventionelle aktuatorer i denne sammenhæng, fordi den er kompakt, let og kan tilpasses geometrien. Der udvikles også en enkel styringsstrategi, hvor ratvinkel og køretøjshastighed er input, affjedringskompression bruges til at beregne den fejl, der skal korrigeres, og servomotorens position er output. Benchmarking giver optimistiske indikationer på, at de mål, DIS har sat for bilen, er realistiske. Nogle simuleringer viser negativ luftmodstand på bagvingen; det tilskrives sandsynligvis bilens nedadgående bagende og/eller simuleringsindstillinger, men den præcise årsag er ikke identificeret. Samlet vurderes projektets overordnede mål at være realiseret, da design og evaluering af bilkrop med aktiv aerodynamik er gennemført inden for den fastlagte projekt-ramme.

[This apstract has been rewritten with the help of AI based on the project's original abstract]

Active Aerodynamics ; Wing Bracket ; Race Car ; Actuation ; Simulations ; Design ; Innovation ; NACA 4412 ; Rear Wing ; Car Body

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