| 1. |
- Chroneer, Zenitha, et al.
(författare)
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Prediktering av extern flödesakustiks påverkan på hyttbuller
- 2019
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vindljud är idag den största ljudkällan i lastbilar vid hastigheter på över 80 km/h. Det är viktigt för säkerheten att få ner ljudnivåerna eftersom denna typ av ljud kan orsaka trötthet och huvudvärk hos föraren. Andra ljudkällor som motorljud och vägljud har det jobbats ganska mycket med att få ner. I framtidens elektriska fordon där drivlineljuden nästan helt är borta kommer vindljuden bli alltmer framträdande. I detta projekt har vis studerat ljudet som bildas runt en a-stolpe och backspegel på en lastbil samt tittat på olika sätt att modellera detta virtuellt. För att korrelera detta mot verkligheten har mätningar gjorts på en specialbyggd lastbil där andra ljudkällor har minimerats. Genom att först studera en generisk geometri har en beräkningsmetodik tagits fram som inkluderar både strömningsfältet (CFD) och transporten av ljudet in i kupén (akustik). Denna metodik har sedan applicerats på en riktig geometri och resultaten har jämförts mot den uppmätta lastbilen. Beräkningarna överensstämmer väl med det som har uppmätts. Man får dock komma ihåg att mätningarna är gjorda utomhus med riktiga vindförhållanden medan beräkningarna är gjorda under perfekta förhållanden. Modellen fångar både det bredbandiga bedraget och i det fallet där vi ser en ton i mätningarna så ser vi även detta i beräkningarna. Slutsatser som kan dras av dessa beräkningar är att det är viktigt att ta med akustiska bidraget, antingen genom direkt modellering eller med analogier. För att fånga frekvensinnehållet krävs det tidsupplösta metoder medan enkla tidsmedelvärderade modeller kan rangordna olika koncept men saknar frekvensinnehållet.
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| 2. |
- Mazeaud, Benoit, et al.
(författare)
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Application of SNGR Method to Compute Aero-Vibro-Acoustics of Heavy-Duty Rear-View Mirrors
- 2019
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Ingår i: 25th AIAA/CEAS Aeroacoustics Conference, 2019. - Reston, Virginia : American Institute of Aeronautics and Astronautics.
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Konferensbidrag (refereegranskat)abstract
- Flow-induced noise inside cab interior (also termed aerodynamics-induced interior noise) is nowadays perceived as a key factor when assessing the quality of heavy-duty vehicles. In order to satisfy the turnaround time required for current product development, a simplified hybrid numerical approach has been adopted. It couples the SNGR (Stochastic Noise Generation and Radiation) method with a finite element method. The SNGR approach uses RANS (Reynolds Averaged Navier Stokes) for fast CFD (Computational Fluid Dynamics) computations, and is based on a stochastic model to synthesize turbulent velocity fluctuations. These fluctuations are then used to reconstruct aeroacoustic sources based on lighthill's equation. Several rear-view mirror configurations have been chosen to validate this numerical approach. The results are in good agreement with the experiments performed on track. The numerical approach is finally demonstrated as a fast method that can be applied to assess and rank early designs in a short time for the purpose of reducing aerodynamics-induced interior noise.
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| 3. |
- Ramesh Babu, Anandh, 1996, et al.
(författare)
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An adaptive cabin air recirculation strategy for an electric truck using a coupled CFD-thermoregulation approach
- 2024
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Ingår i: International Journal of Heat and Mass Transfer. - 0017-9310. ; 221
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Tidskriftsartikel (refereegranskat)abstract
- Cabin climatization is one of the largest auxiliary loads in an electric vehicle, and its performance significantly affects the driving range. Recirculating climatized air from the cabin has been shown to reduce energy consumption, but at the risk of fogging the windows and deteriorating the air quality. Therefore, many automobile manufacturers refrain from adopting it at low ambient temperatures. In this paper, an adaptive recirculation strategy that takes these issues into account is proposed and studied on an electric truck cabin while heating. Numerical simulations were performed using a coupled CFD-thermoregulation model, with the consideration of humidity and CO2. The JOS-3 thermoregulation model was employed for estimations of skin temperatures and evaporation of vapor from the skin, and the Berkeley comfort model was used to evaluate the comfort metrics. Ten scenarios were considered at various vehicle speeds, temperatures, and relative humidity levels while evaluating them with and without the proposed return-air strategy. The controller adapted between humidity and CO2-critical conditions during run-time. The fresh-air mass flow requirements reduced with increasing difference between the setpoint and ambient vapor mass fractions under humidity critical conditions, and plateaued at 10 g/s where CO2 was more critical. The proposed strategy provided energy savings ranging from 9% to 34% depending on the operating condition.
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| 4. |
- Yao, Huadong, 1982, et al.
(författare)
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Investigation of Interior Noise from Generic Side- View Mirror Using Incompressible and Compressible Solvers of des and les
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2018-April
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Tidskriftsartikel (refereegranskat)abstract
- Exterior turbulent flow is an important source of automobile cabin interior noise. The turbulent flow impacts the windows of the cabins to excite the structural vibration that emits the interior noise. Meanwhile, the exterior noise generated from the turbulent flow can also cause the window vibration and generate the interior noise. Side-view mirrors mounted upstream of the windows are one of the predominant body parts inducing the turbulent flow. In this paper, we investigate the interior noise caused by a generic side-view mirror. The interior noise propagates in a cuboid cavity with a rectangular glass window. The exterior flow and the exterior noise are computed using advanced CFD methods: compressible large eddy simulation, compressible detached eddy simulation (DES), incompressible DES, and incompressible DES coupled with an acoustic wave model. The last method is used to simulate the hydrodynamic and acoustic pressure separately. The pressure fluctuations of the flow and noise are imposed on the window in the computation of the interior noise, but the reversal effect of the window vibration feeding back on the flow is neglected in the flow simulation. The localized flow characteristics are discussed. The energetic surface pressure appears in the regions where the shear layer from the mirror side edge impinges on the window. The contributions of the hydrodynamic and acoustic pressure to the interior noise are quantified. The acoustic component is found to be more efficient in the interior noise generation and to play the dominant role at high frequencies.
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| 5. |
- Yao, Huadong, 1982, et al.
(författare)
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Simplifications Applied to Simulation of Turbulence Induced by a Side View Mirror of a Full-Scale Truck Using des
- 2018
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 2018-April
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the turbulent flow induced by a production side-view mirror assembled on a full-scale production truck is simulated using a compressible k- SST detached eddy simulation (DES) approach - the improved delayed DES (IDDES). The truck configuration consists of a compartment and a trailer. Due to the large size and geometric complexity of the configuration, some simplifications are applied to the simulation. A purpose of this work is to investigate whether the simplifications are suitable to obtain the reasonable properties of the flow near the side-view mirror. Another objective is to study the aerodynamic performances of the mirror. The configuration is simplified regarding two treatments. The first treatment is to retain the key exterior components of the truck body while removing the small gaps and structures. Furthermore, the trailer is shaped in an apex-truncated square pyramid. This simplification is proposed based on the assumption that the downstream flow near the trailer has limited effect on the flow near the mirror. To assess the influences of the simplifications, the flow fields computed from the original and simplified configurations are compared. The regions on the window that are subjected to significant hydrodynamic impingement are identified. The mirror and A-pillar introduce the impingement. The frequency spectra of the surface pressure fluctuations on the window are studied. The frequencies of the peaks in the spectra are the same as the characteristic frequencies of the free shear layers that develop from the mirror side-edges near the window. The simplifications are found as feasible treatments to reproduce the flow characteristics of the original geometry.
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