Insights into Rear Surface Contamination Using Simulation of Road Spray and Aerodynamics

Gaylard, Adrian; Pitman, John; Jilesen, Jonathan; Gagliardi, A.; Duncan, Bradley D.; Wanderer, John; Константинов, А Ю

doi:10.4271/2014-01-0610

Cited by 26 publications

(13 citation statements)

References 16 publications

(20 reference statements)

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“…It can degrade the performance of lighting, obstruct visibility through the rear window and lead to glass degradation due to abrasion and premature wear of wiper blades [1]. Contamination can also influence the performance of rear camera systems by obstructing camera lenses [2].…”

Section: Introductionmentioning

confidence: 99%

Experimental and Computational Study of Vehicle Surface Contamination on a Generic Bluff Body

Kabanovs¹,

Varney²,

Garmory³

et al. 2016

SAE Technical Paper Series

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This paper focuses on methods used to model vehicle surface contamination arising as a result of rear wake aerodynamics. Besides being unsightly, contamination, such as self-soiling from rear tyre spray, can degrade the performance of lighting, rear view cameras and obstruct visibility through windows. In order to accurately predict likely contamination patterns, it is necessary to consider the aerodynamics and multiphase spray processes together. This paper presents an experimental and numerical (CFD) investigation of the phenomenon.The experimental study investigates contamination with controlled conditions in a wind tunnel using a generic bluff body (the Windsor model.) Contamination is represented by a water spray located beneath the rear of the vehicle. The aim is to investigate the fundamentals of contamination in a case where both flow field and contamination patterns can be measured, and also to provide validation of modelling techniques in a case where flow and spray conditions are known.CFD results were obtained using both steady RANS and unsteady URANS solvers, combined with particle tracking methods. Steady RANS does not capture the wake structures accurately and this affects the contamination prediction. URANS is able to recover the large-scale wake unsteadiness seen in the experimental data, but the difference between the experimental and computational contamination distributions is still notable. The CFD is also able to provide further insight by showing the behaviour of particles of different sizes. Large particles are found to take on a ballistic trajectory and penetrate the wake. In contrast, small particles are shown to be less likely to become entrained into the wake.

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Section: Introductionmentioning

confidence: 99%

Experimental and Computational Study of Vehicle Surface Contamination on a Generic Bluff Body

Kabanovs¹,

Varney²,

Garmory³

et al. 2016

SAE Technical Paper Series

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show abstract

“…33 With the addition of two-way momentum coupling between the particles and air, this technique was able to predict rear-surface contamination patterns for an SUV together with the changes seen when spray was released at the front, the rear and all the wheels. 87 Figure 12 provides an example of a rear-surface contamination pattern obtained with this method; a comparison with Figure 11 shows that, although deposition on the rear screen is overstated, the overall distribution of contaminant on the tailgate is well recovered. This represents a convergence between soiling and EWM simulation methodologies, i.e.…”

Section: Numerical Simulationsmentioning

confidence: 99%

Surface contamination of cars: A review

Gaylard

Kirwan

Lockerby

2017

Proceedings of the Institution of Mechanical Engineers, Part D:

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This review surveys the problem of surface contamination of cars, which poses a growing engineering challenge to vehicle manufacturers, operators and users. Both the vision of drivers and the visibility of vehicles need to be maintained under a wide range of environmental conditions. This requires managing the flow of surface water on windscreens and side glazing. The rate of deposition of solid contaminants on glazing, lights, licence plates and external mirrors also needs to be minimised. Maintaining vehicle aesthetics and limiting the transfer of contaminants to the hands and clothes of users from soiled surfaces are also significant issues. Recently, keeping camera lenses clean has emerged as a key concern, as these systems transition from occasional manoeuvring aids to sensors for safety systems. The deposition of water and solid contaminants on to car surfaces is strongly influenced by unsteady vehicle aerodynamic effects. Airborne water droplets falling as rain or lifted as spray by tyres interact with wakes, vortices and shear flows and accumulate on vehicle surfaces as a consequence. The same aerodynamic effects also control the movement of surface water droplets, rivulets and films; hence, particular attention is paid to the management of surface water over the front side glass and the deposition of contaminants on the rear surfaces. The test methods used in the automotive industry are reviewed, as are the numerical simulation techniques.

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“…Whereas much published work [7,8,9,10] has focused on the final outcome with regard to the surface contamination, or on comparing CFD simulations with experimental work, the work presented here studies the variation of base contamination with changing roof slant angle. Roof slant angle variations were selected for the study because they are commonly employed as a drag reduction method [11].…”

Section: Introductionmentioning

confidence: 99%

“…A single nozzle, installed 86 mm behind the rear near-side wheel center and directed 45 degrees downstream was used. This location was chosen to reasonably represent the typical source [7] of self-soiling and ensure that sufficient particles of fluid were entrained in the body and wheel wakes. Using a single source, rather than one located behind each rear wheel ensures that a clear analysis of the source and outcome can be achieved.…”

Section: Seeding Setupmentioning

confidence: 99%