School of Aerospace, Transport and Manufacturing (SATM)

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Browsing School of Aerospace, Transport and Manufacturing (SATM) by Type "Technical Report"

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    Integrated numerical and experimental workflow for high-performance vehicle aerodynamics
    (Society of Automotive Engineers, 2024-02-06) Rijns, Steven; Teschner, Tom-Robin; Blackburn, Kim; Brighton, James
    The high-performance and motorsport vehicle sectors are pushing the performance frontiers of aerodynamically efficient vehicles. Well-balanced use of accurate and consistent numerical simulation tools in combination with wind tunnel experiments is crucial for cost-effective aerodynamic research and development processes. Therefore, this study assesses the simulation performance of four Reynolds-averaged Navier–Stokes (RANS) turbulence models in relation to experimental and high-fidelity delayed detached eddy simulation (DDES) data for the aerodynamic assessment of a high-performance variant of the DrivAer model (DrivAer hp-F). The influences of predominant wind tunnel conditions on the vehicle’s aerodynamic force coefficients and flow field are also investigated. Additionally, a novel CFD-based blockage correction method is introduced and applied to evaluate the accuracy of conventional blockage correction methods. Among the RANS models, the k-ω SST model exhibited notable relative accuracy in the prediction of force coefficients and demonstrated generally the best correlation with detailed DDES flow field data. The wind tunnel blockage effect caused a 9% increase in downforce and 16% increase in drag, whereas the interference effects from the overhead measurement system reduced downforce by 4% and drag by 8%. The novel CFD-based blockage correction method confirmed that conventional blockage correction methods adequately estimate the dynamic pressure in proximity of a wind tunnel model (<3%), but do not consider local effects on downforce and drag individually. Overall, the research extends beyond prior work on automotive applications, contributing to the advancement of aerodynamic research methodologies suitable for the complex flow fields of high-performance vehicles.
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    Investigation of seat suspensions with embedded negative stiffness elements for isolating bus users’ whole-body vibrations
    (Society of Automotive Engineers, 2021-03-17) Papaioannou, Georgios; Sekulic, Dragan; Velenis, Efstathios; Antoniadis, Ioannis
    Bus drivers are a group at risk of often suffering from musculoskeletal problems, such as low-back pain, while bus passengers on the last-row seats experience accelerations of high values. In this paper, the contribution of K-seat in decreasing the above concern is investigated with a detailed simulation study. The K-seat model, a seat with a suspension that functions according to the KDamper concept, which combines a negative stiffness element with a passive one, is benchmarked against the conventional passive seat (PS) in terms of comfort when applied to different bus users’ seats. More specifically, it is tested in the driver’s and two different passengers’ seats, one from the rear overhang and one from the middle part. For the benchmark shake, both are optimized by applying excitations that correspond to real intercity bus floor responses when it drives over a real road profile. Then a human model is placed on the seats in order to compare their optimum solutions in terms of the user’s whole-body vibrations (WBVs), using objective comfort metrics. Based on the results, the K-seat improves significantly the comfort of the users (~92%) compared to the PS, while it achieves a similar decrease in the maximum values of the user’s back accelerations (~97%).