A Parametric Study of Automotive Rear End Geometries on Rear Soiling

Kabanovs, Anton; Hodgson, Graham; Garmory, Andrew; Passmore, Martin A.; Gaylard, Adrian

doi:10.4271/2017-01-1511

Cited by 11 publications

(12 citation statements)

References 20 publications

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“…Kabanovs et al [14] and [12], demonstrate broadly good correlation between experiments and CFD for base contamination, however the numerical results showed a narrow area of high soiling stretching along the edge of the base, not present in the experimental data. This was proposed to be due to a large fraction of small, low-inertia particles in the numerical spray.…”

Section: Introductionmentioning

confidence: 87%

“…It was therefore found to be necessary to model the full time history of the particle paths rather than using a statistically averaged description of the turbulent dispersion. It has been shown that eddy resolving methods are required to accurately predict the flow field around bluff bodies and produce encouraging results of base soiling [13], as well as simulate the soiling trends with changes to vehicle geometry [14].…”

Section: Introductionmentioning

confidence: 99%

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Modelling the Effect of Spray Breakup, Coalescence, and Evaporation on Vehicle Surface Contamination Dynamics

Kabanovs¹,

Garmory²,

Passmore³

et al. 2018

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

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Vehicle surface contamination is an important design consideration as it affects drivers' vision and the performance of on board camera and sensor systems. Previous work has shown that eddy resolving methods are able to accurately capture the flow field and particle transport, leading to good agreement for vehicle soiling with experiments. What is less clear is whether the secondary break-up, coalescence and evaporation of liquid particles play an important role in spray dynamics. The work reported here attempts to answer this and also give an idea of the computational cost associated with these extra physics models. A quarter scale generic SUV model is used as a test case in which the continuous phase is solved using the Spalart-Allmaras IDDES model. The dispersed phase is computed concurrently with the continuous phase using the Lagrangian approach. The TAB secondary break-up and the stochastic O'Rourke coalescence models are used. The spray's rate of evaporation is calculated based on the relative humidity encountered on a typical October day in Britain. The secondary break-up model is found to be redundant, possibly due to the properties of spray. The coalescence model predicts high coalescence of particles close to the source and improves agreement with experiment, although at a high computational cost. Including evaporation removes small particles from the simulation and reduces overall contamination. When used along the coalescence model, evaporation is found to be negligible as it does not influence large particles to the same extent as it affects small particles. This suggests that droplet physics models need to be considered together as they can have a strong effect on each other as well as vehicle soiling. Here, we show that coalescence can be accounted for by using the time-averaged spray, obtained outside the region of high coalescence. This gives a very good agreement with experiment.

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Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Modelling the Effect of Spray Breakup, Coalescence, and Evaporation on Vehicle Surface Contamination Dynamics

Kabanovs¹,

Garmory²,

Passmore³

et al. 2018

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

Self Cite

View full text Add to dashboard Cite

show abstract

“…Finally, this methodology needs applying to actual base contamination tests in a wind tunnel. Testing of any model configuration should be undertaken with different spray durations since it has been previously shown [11] that there are low frequency events that may alter the rate of contamination. The averaged deposition rates can then be compared to simulation work, finally providing sensible objective comparisons between the two.…”

Section: Summary/conclusionmentioning

confidence: 99%

“…To improve the ability to compare experiments and computational contamination Kabanovs et al [10,11] report on tests on quarter-scale simplified automotive geometries using a UV dye to dope water injected as a spray behind the left hand rear wheel. Using a single injection point was designed to assist understanding of the final result.…”

mentioning

confidence: 99%

“…The method described in this paper considers variations of illumination intensity coupled with a calibration vessel to initially study known droplets before being applied to a simplified contamination experiment with validated results for the total mass of fluid. If this method were applied to a contamination test with known spray duration, such as Kabanovs [11], then average contamination rates can be obtained with full spatial information so that validation of the CFD and detailed analysis of the contamination can be performed.…”

mentioning

confidence: 99%

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An Objective Measure for Automotive Surface Contamination

Hodgson¹,

Passmore²,

Garmory³

et al. 2018

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

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Surface contamination, or soiling, of the exterior of road vehicles can be unsightly, reduce visibility and customer satisfaction and, with the increasing application of surface mounted sensors, can degrade the performance of advanced driver assistance systems. Experimental methods of evaluating surface contamination are increasingly used in the product development process, but the results are generally subjective. The use of computational methods for predicting contamination make objective measures possible, but comparable data from experiment is an important validation requirement. This paper describes the development of an objective measure of surface contamination arising during experiments. A series of controlled experiments using Ultra Violet (UV) dye doped water are conducted to develop a robust methodology. This process is then applied to a simplified contamination test. An image of a surface, illuminated by an UV lamp, is captured after every test along with a calibration vessel with known fluid depth. The image is processed to remove the influence of variation in incident illumination. The total mass of contamination deposited is then calculated using the calibration vessel to provide the required local fluid depths. The paper includes validation of the technique.

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