A Comparison Between On-Road and Wind Tunnel Surface Pressure Measurements on a Mid-Sized Hatchback

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

Dominy

et al. 2011

. (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.

Section: Figure 5 Location Of Pressure Tappings and Surface Microphonesmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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

Oettle

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

Dominy

et al. 2011

“…The assessment of the transient conditions experienced by a moving vehicle was pioneered by Watkins [5] and, for example Watkins, Saunders and Hoffmann [6]. Similar assessments have been included in Lawson et al [7], [2], Lindener et al [8], Oettle et al [9] and Wojciak et al [10]. The definitive work is that of Wordley [11] including [12], [13].…”

Section: Time Varying Flowsmentioning

confidence: 99%

Cross Winds and Transients: Reality, Simulation and Effects

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

2011

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. ABSTRACTThis paper provides a published counterpart to the address of the same title at the 2010 SAE World Congress.A vehicle on the road encounters an unsteady flow due to turbulence in the natural wind, due to the unsteady wakes of other vehicles and as a result of traversing through the stationary wakes of road side obstacles. This last term is of greatest significance.Various works related to the characterization, simulation and effects of on-road turbulence are compared together on the turbulence spectrum to highlight differences and similarities. The different works involve different geometries and different approaches to simulating cross wind transients but together these works provide guidance on the most important aspects of the unsteadiness.On-road transients include a range of length scales spanning several orders of magnitude but the most important scales are in the in the 2-20 vehicle length range. There are significant levels of unsteadiness experienced on-road in this region and the corresponding frequencies are high enough that a dynamic test is required to correctly determine the vehicle response. Fluctuations at these scales generate significant unsteady loads (aerodynamic admittance typically 0.6-1.4) and the corresponding frequencies can adversely affect vehicle dynamics.The generation of scales larger than the scale of the vehicle is impractical with passive grids and so active turbulence generation systems are preferred. These can be classified into lift and drag-based devices. Lift-based devices provide better control of the turbulence but can only just reproduce the smaller scales in the 2-20 vehicle length range. Different moving model approaches are also discussed. CFD offers real advantages through its ability to allow arbitrary time-varying boundary conditions.

“…The coordinate system that is used throughout the paper is shown in Figure 1 and Figure 2. Surface pressure investigations were also performed the European two box hatchback vehicle described by Lawson et al (2007) [14]. The same roof-mounted probe as corresponding coordinate system was used as with the cabin noise measurements.…”

Section: Test Vehiclesmentioning

confidence: 99%

“…Surface pressures were measured on the front sideglass using both surface-mounted "lollipop" taps on the standard glass sideglass as described by [14], and using a drilled Perspex sideglass moulded to the shape of the production glass with 1.24 mm OD hypodermic stainless steel tubing bonded in position. Pressures were measured using separate SensorTechnics HCLA12X5DB pressure transducers located inside the cabin connected to each surface taping via PVC tubing.…”

Section: Sideglass Pressuresmentioning

confidence: 99%

Evaluation of the Aerodynamic and Aeroacoustic Response of a Vehicle to Transient Flow Conditions

Oettle

Mankowski

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

et al. 2013

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.