Generation of a Controlled Level of Turbulence in the Pininfarina Wind Tunnel for the Measurement of Unsteady Aerodynamics and Aeroacoustics

Cogotti, A.

doi:10.4271/2003-01-0430

Cited by 58 publications

(19 citation statements)

References 19 publications

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“…Such devices are capable of generating the large length scales representative of the majority of on-road gusts. In addition, it has been shown that active drag-based devices such as the upstream deployable blades at Pininfarina [20,21] can be used to generate dynamically yawing flow by controlling the relative phasing of the opening and closing of the blades [22].…”

Section: Introductionmentioning

confidence: 99%

A Fully Coupled, 6 Degree-of-Freedom, Aerodynamic and Vehicle Handling Crosswind Simulation using the DrivAer Model

Forbes¹,

Page²,

Passmore³

et al. 2016

SAE Int. J. Passeng. Cars - Mech. Syst.

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INTRODUCTIONIn the UK, average annual wind speeds fall in the range of 4-5m/s, which at typical vehicle speeds of 100km/h can produce flow yaw angles up to 10° [1]. In contrast, maximum mean hourly wind speeds of up to 24m/s over flat, open, central parts of the UK have been recorded, albeit with a probability of occurring once in 50-year period [1,2]. Whilst data describing instantaneous peak values is rare, values greater than this mean can be expected. Nevertheless, these speeds correspond to a much larger maximum flow yaw angle of approximately 40°. Such high angles and speeds present a safety concern as it will be shown that at these values, the forces acting on the vehicle are large enough to cause a substantial course deviation and in some cases, are large enough for the vehicle to encroach upon adjacent lanes.This issue will become even more prevalent with the current trend towards lighter, more fuel efficient vehicles, in a bid to meet emissions regulations brought about by the `Worldwide Harmonized Light Vehicles Test Procedure' (WLTP) [3].It is generally assumed that as any lateral or yaw accelerations are sensed a driver will be able to provide an adequate counter response to a gust to prevent a significant deviation. However, this is not always the case because when the frequency of the gust is combined with the drivers inputs the driver's response can amplify the vehicle's deviation. This is shown by Wagner and Wiedemann [4], within a frequency range of 0.5-2Hz, to occur as the vehicle motion due to the crosswind and the driver's steering input approach an in-phase state, peaking at a frequency of 1.4Hz. For frequencies <0.5Hz, the driver typically has a positive influence on the vehicle's response, as the gust and loads acting on the vehicle are quasi-steady. Whereas at higher frequencies >2Hz, the driver has little to no influence, as the gust has passed before it is felt.In order to assess the complete vehicle-driver response to such an event, a flow disturbance has to be generated, either naturally or artificially. The aerodynamic response of a vehicle during a crosswind has been investigated using numerous methods. On road vehicle testing [5,6,7,8,9] is often preferred as it places a representative driver and vehicle in a real-world environment, whilst crosswind generators beside test tracks [10,11] offer a degree of control over gust parameters.An International Standard ISO 12021:2010 [13] has been derived in an attempt to standardize such facilities. These guidelines appear to be based on the work of Howell [11], in which a trifurcated tail pipe attached to the exhaust of a jet engine was used to determine the behavior of a small Sports Utility Vehicle (SUV) when passing Adrian P. Gaylard Jaguar Land Rover ABSTRACTIn a real-world environment, a vehicle on the road is subjected to a range of flow yaw angles, the most severe of which can impact handling and stability. A fully coupled, six degrees-of-freedom CFD and vehicle handling simulation has modelled the complete closed loop system. Vary...

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Section: Introductionmentioning

confidence: 99%

A Fully Coupled, 6 Degree-of-Freedom, Aerodynamic and Vehicle Handling Crosswind Simulation using the DrivAer Model

Forbes¹,

Page²,

Passmore³

et al. 2016

SAE Int. J. Passeng. Cars - Mech. Syst.

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“…The turbulence generation system installed in the Pininfarina wind tunnel (Figure 4), Cogotti [20], [21] is essentially a drag-based (bluff) active device. Varying the width of the bluff spires has some impact on the unsteady scales generated and controlling the relative phasing of the opening and closing of the different spires can even provide an overall dynamic yaw (Carlino [22]).…”

Section: Active Drag-based (Bluff) Devicesmentioning

confidence: 99%

A Wind Tunnel Simulation Facility for On-Road Transients

Mankowski¹,

Sims-Williams²,

Dominy³

2014

SAE Int. J. Passeng. Cars - Mech. Syst.

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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.

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“…Turbulence generation systems have been installed in aeroacoustic wind tunnels as shown Cogotti (2003Cogotti ( , 2005 [5] [6], which can be used to assess cabin noise under these turbulent conditions. Passive systems, such as those placing a vehicle upstream of the test section as described by Saunders and Mansour (2000) [7], Watkins et al (2001) [8], Cogotti (2003) [5] amongst others, tend to simulate only a limited range of conditions that a vehicle can experience while traversing the on-road environment. Active methods allow a wider range of conditions to be simulated and as these methods improve, better comparisons can be made between the on-road environment and the aeroacoustic wind tunnel.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Unsteady On-Road Flow Conditions on Cabin Noise: Spectral and Geometric Dependence

Oettle

Sims-Williams

Dominy

et al. 2011

SAE Int. J. Passeng. Cars – Mech. Syst.

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. (2011) 'The eects of unsteady on-road ow conditions on cabin noise : spectral and geometric dependence.', SAE International journal of passenger cars. Mechanical systems., 4 (1). pp. 120-130. Further information on publisher's website:http://dx.doi.org/10.4271/2011-01-0159Publisher's copyright statement:Additional information: Use policyThe 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. ABSTRACTThe in-cabin sound pressure level response of a vehicle in yawed wind conditions can differ significantly between the smooth flow conditions of the aeroacoustic wind tunnel and the higher turbulence, transient flow conditions experienced on the road. Previous research has shown that under low turbulence conditions there is close agreement between the variation with yaw of in-cabin sound pressure level on the road and in the wind tunnel. However, under transient conditions, sound pressure levels on the road were found to show a smaller increase due to yaw than predicted by the wind tunnel, specifically near the leeward sideglass region.The research presented here investigates the links between transient flow and aeroacoustics. The effect of small geometry changes upon the aeroacoustic response of the vehicle has been investigated. It was found that sideglass pressures showed close agreement at all turbulence levels while surface sound pressure levels also showed similar behaviour under a wide range of on-road flow conditions. While the overall sideglass sound pressure level changed under the various yaw conditions, the change in shape of the frequency spectrum was less significant.Geometry changes made to a base vehicle reduced the sensitivity of the in-cabin noise to on-road turbulence, showing that shape-change can modify sensitivity to on-road turbulence.

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Generation of a Controlled Level of Turbulence in the Pininfarina Wind Tunnel for the Measurement of Unsteady Aerodynamics and Aeroacoustics

Cited by 58 publications

References 19 publications

A Fully Coupled, 6 Degree-of-Freedom, Aerodynamic and Vehicle Handling Crosswind Simulation using the DrivAer Model

A Fully Coupled, 6 Degree-of-Freedom, Aerodynamic and Vehicle Handling Crosswind Simulation using the DrivAer Model

A Wind Tunnel Simulation Facility for On-Road Transients

The Effects of Unsteady On-Road Flow Conditions on Cabin Noise: Spectral and Geometric Dependence

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