A Computational Approach to Evaluate the Vehicle Interior Noise from Greenhouse Wind Noise Sources

Lepley, David J.; Graf, Anna; Powell, Roger A.; Senthooran, Sivapalan

doi:10.4271/2010-01-0285

Cited by 20 publications

(4 citation statements)

References 5 publications

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“…In this paper, CFD/SEA methods used previously [1,2,4] to simulate side glass contributions to interior wind noise have been extended to handle vehicle underbody panels. The CFD/SEA side glass method was additionally validated over changes in flow speed and yaw.…”

Section: Discussionmentioning

confidence: 99%

“…Multiple technologies are required in order to efficiently simulate the physics of this process. A method has been reported on successful digital simulation of wind noise from side glass panels on a sedan by Moron et al [1] and on an SUV by Lepley et al [2] using a combination of CFD for the air flow and SEA for the structural acoustics. In these two studies, the frequency range reported was 250-5000 Hz in third octave bands and both also showed proper design prediction with alternate side mirrors.…”

Section: Introductionmentioning

confidence: 98%

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Simulation of Underbody Contribution of Wind Noise in a Passenger Automobile

Powell¹,

Moron²,

Balasubramanian³

et al. 2013

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

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Wind noise is a significant source of interior noise in automobiles at cruising conditions, potentially creating dissatisfaction with vehicle quality. While wind noise contributions at higher frequencies usually originate with transmission through greenhouse panels and sealing, the contribution coming from the underbody area often dominates the interior noise spectrum at lower frequencies. Continued pressure to reduce fuel consumption in new designs is causing more emphasis on aerodynamic performance, to reduce drag by careful management of underbody airflow at cruise. Simulation of this airflow by Computational Fluid Dynamics (CFD) tools allows early optimization of underbody shapes before expensive hardware prototypes are feasible. By combining unsteady CFD-predicted loads on the underbody panels with a structural acoustic model of the vehicle, underbody wind noise transmission could be considered in the early design phases. This paper describes a numerical process capable of simulating underbody contributions to interior wind noise. A CFD model based on the Lattice Boltzmann Method is applied to generate fluctuating pressure loads on the underbody. Structural and acoustic loads are then calculated and applied to a vehicle noise model based on Statistical Energy Analysis, with certain parameter updates from a finite element model to predict accurately the noise transmission through the underbody panels to the driver's ear location. Interior noise validation has been achieved on a series production sedan in an aeroacoustic wind tunnel, making use of acoustic insulation materials to block greenhouse transmission. Variation in flow speed and microphone location is included to verify prediction capability of this completely numerical process.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%

Simulation of Underbody Contribution of Wind Noise in a Passenger Automobile

Powell¹,

Moron²,

Balasubramanian³

et al. 2013

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

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“…Recently this technique has started to become more widespread as work continues to assess the accuracy of numerical noise predications against experimental data. Studies include those of Liet al (2003) andLepley et al (2010), where surface microphones were used to correlate CFD data in a study which aimed to simulate the noise transmission path from the external surfaces of the vehicle to the interior cabin noise.…”

mentioning

confidence: 99%

“…Amongst others, both LES and LBM are widely used in such studies.An early application of this work byDuncan et al (2002) explored LBM to separate different frequencies of fluctuations on an idealised body, through the use of spectral techniques to help identify noise-producing areas. More recent developments include coupling with structural solvers to determine the impact of door-seal shape changes on aeroacoustics,Blumrich (2009), and the structural transmission paths of external sound sources to predict cabin noise,Lepley et al (2010).The research presented in this thesis concerns transient aeroacoustics. This is particularly challenging from a CFD computational expense perspective, since these simulations generally combine an acoustic need for a small time-step with longer simulation times to not only simulate lower acoustic frequencies, but to capture the transient nature of the flow.…”

mentioning

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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