Aerodynamics and Aeroacoustics of Passenger Cars in a Controlled High Turbulence Flow: Some New Results

Cogotti, A.; Cardano, D.; Carlino, G.; Cogotti, F.

doi:10.4271/2005-01-1455

Cited by 20 publications

(6 citation statements)

References 14 publications

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“…Saunders, Watkins, Cooper et al were amongst those advocating the simulation of real-world turbulence in automotive wind tunnel testing as a result of data they derived from on-road tests [26][27][28][29][30][31][32]. The first full-scale active system was introduced at Pininfarina [ [33][34][35][36][37] and was followed by model and full-scale systems at FKFS [38]. The model-scale tunnel at Durham University [39] also has an active system whilst passive systems have also been introduced as optional test capabilities in the wind tunnels of S2A [40] and NRC [41].…”

Section: Introductionmentioning

confidence: 99%

“…None actually go so far as to provide the ability to test multiple vehicles, but they do provide an onset flow which aims to simulate following another vehicle. The Turbulence Generation System [33][34][35][36][37] contained within the nozzle of the Pininfarina wind tunnel provides modes of operation which allows the test vehicle to experience flow regimes which simulates being in the wake of another vehicle either directly in-line or with a lateral offset. The system is also capable of producing a flow to simulate the downwash effects produced by road cars or an upwash for a racing car simulations [34,35].…”

Section: Introductionmentioning

confidence: 99%

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An Investigation of Aerodynamic Effects of Body Morphing for Passenger Cars in Close-Proximity

Good

Resnick

Boardman

et al. 2021

Fluids

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The potential energy-saving benefit for vehicles when travelling in a ‘platoon’ formation results from the reduction in total aerodynamic drag which may result from the interaction of bluff bodies in close-proximity. Early investigations of platooning, prompted by problems of congestion, had shown the potential for drag reduction but was not pursued. More recently, technologies developed for connected-autonomous vehicle control have provided a renewed interest in platooning particularly within the commercial vehicle industry. To date, most aerodynamics-based considerations of platooning have been conducted to assess the sensitivity of drag-saving to vehicle spacing and were based on formations of identically shaped constituents. In this study, the interest was the sensitivity of drag-saving to the shape of the individual platoon constituents. A new reference car, the Resnick model, was specially designed to include front and rear-end add-on sections to make distinct changes in profile form and simulate large-scale body morphing. The results of wind tunnel tests on small-scale models suggested that current trends in low-drag styling may not provide the ideal shape for platoon constituent members and that optimised forms are likely to be dependent upon position in the platoon.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

An Investigation of Aerodynamic Effects of Body Morphing for Passenger Cars in Close-Proximity

Good

Resnick

Boardman

et al. 2021

Fluids

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“…The motion of the flaps is sufficiently quiet to allow acoustic measurements to be taken, with the generation system also used by Cogotti et al (2005) side force. Therefore, from this steady state comparison, it is likely that the notchback model is judged more sensitive to crosswind than the hatchback model.…”

Section: Introduction and Aimsmentioning

confidence: 99%

The Effects of Unsteady On-Road Flow Conditions on Cabin Noise

Oettle¹,

Sims-Williams²,

Dominy³

et al. 2010

SAE Technical Paper Series

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On-road, a vehicle experiences unsteady flow conditions due to turbulence in the natural wind, moving through the unsteady wakes of other road vehicles and travelling through the stationary wakes generated by roadside obstacles. There is increasing concern about potential differences between steady flow conditions that are typically used for development and the transient conditions that occur on-road. This work considers whether steady techniques are able to predict the unsteady results measured on-road, the impact of this unsteadiness on the noise perceived in the cabin and whether minor changes made to the geometry of the vehicle could affect this. Both external aerodynamic and acoustic measurements were taken using a full-size vehicle combined with measurements of the noise inside the cabin. Data collection took place on-road under a range of wind conditions to accurately measure the response of the vehicle to oncoming flow unsteadiness, with steady-state measurements taking place in full-scale aeroacoustic wind tunnels.Overall it was demonstrated that, using a variety of temporal and spectral approaches, steady techniques were able to predict unsteady on-road results well enough to assess cabin noise by correctly taking into account the varying on-road flow conditions. Aerodynamic admittance values remained less than unity in the sideglass region of the vehicle, with the exception of the the region nearest the A-pillar. The reducing unsteady energy at frequencies greater than 10 Hz, combined with the corresponding roll-off in admittance, implies that unsteady frequencies below 10 Hz affect the vehicle most, where the response remains quasi-steady.Quasi-steady cabin noise simulations allowed a subjective assessment of the predicted unsteady cabin noise, where the impact of cabin noise modulations were quantified and found to be important to perception. Minor geometry changes affected the sensitivity of cabin noise to changes in yaw angle, altering modulation and therefore having an important impact on the unsteady wind noise perceived on-road.iii DeclarationThe work in this thesis is based on research carried out at the School of Engineering and Computing Sciences, Durham University, UK. No part of this thesis has been submitted elsewhere for any other degree or qualification and it all my own work unless referenced to the contrary in the text.

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“…Passive methods suffer from not being able to generate the longer turbulence length scales as would be experienced onroad 99 . Alternatively, active methods using aerofoils or vanes positioned upstream of the test section to generate varying levels of turbulence can be used [100][101][102] , allowing a number of transient aeroacoustic studies to take place, including [103][104][105] . CFD provides more freedom to include transient inlet conditions without being limited by the hardware required to generate them.…”

Section: Simulation Of Transient Onset Conditionsmentioning

confidence: 99%

Automotive aeroacoustics: An overview

Oettle

Sims-Williams

2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractVehicle aeroacoustic performance has a strong influence on customer perception and also has importance for safety and comfort. Wind noise performance was once differentiated by the quality of sealing. Today, achieving competitive wind noise performance also depends on minimising aeroacoustic noise sources generated by the vehicle form, and on attenuation in the noise pathway from sources on the exterior to the vehicle interior. Attenuation in the noise pathway from sources on the exterior to the vehicle interior, especially through glazed surfaces, will continue to play an important role in controlling cabin noise, with a particular emphasis on achieving attenuation efficiently in terms of component mass. The human brain is not only sensitive towards the level of steady broadband noise, but distinctive features such as tonality or modulation draw the attention of the vehicle occupant and impact negatively on perception. Complex indices are often required to define good wind noise performance. This includes the consideration of multiple frequency bands and effects of the range of yaw angles experienced on-road. A key to achieving future vehicle refinement is bringing together an understanding of unsteady onset flow conditions, their impact on cabin sound pressure level and modulation and in turn the impact of noise level and modulation on psychoacoustic perception.

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Aerodynamics and Aeroacoustics of Passenger Cars in a Controlled High Turbulence Flow: Some New Results

Cited by 20 publications

References 14 publications

An Investigation of Aerodynamic Effects of Body Morphing for Passenger Cars in Close-Proximity

An Investigation of Aerodynamic Effects of Body Morphing for Passenger Cars in Close-Proximity

The Effects of Unsteady On-Road Flow Conditions on Cabin Noise

Automotive aeroacoustics: An overview

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