Low Drag Automotive Mirrors Using Passive Jet Flow Control

Wang, Jianlei; Bartow, William; Moreyra, Andres; Woyczynski, Gregory; Lefebvre, Alexis; Carrington, Edward; Zha, Gecheng

doi:10.4271/2014-01-0584

Cited by 8 publications

(4 citation statements)

References 9 publications

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“…A concept known as Jet Boat Tail(JBT) has been previously suggested and proven effective to reduce the drag of automobile rear view mirrors by Zha and his team [10,11,12,13,14]. This method is effective and convenient as it does not interfere with the base surface and does not create increase of the size of the body.…”

mentioning

confidence: 99%

Bluff Body Drag Reduction Using Passive Flow Control of Jet Boat Tail

Hirst

Yang

et al. 2015

SAE Int. J. Commer. Veh.

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Aerodynamic efficiency is at the forefront of concern when designing commercial road vehicles. As such, reducing aerodynamic drag has become the focal point of many research topics. Still, however, many commercial vehicles that are employed for the transportation of people and goods experience very high amounts of drag. Many of these high drag vehicles utilize configurations similar to rectangular prisms. Such vehicles include semi-trailer trucks, vans, buses, and SUV's. These vehicles are responsible for a substantial amount of miles traveled. Single-unit and combination trucks collectively consumed over 44 million gallons of gas in the US in 2010, accounting for over 26% of all gasoline consumed by motor vehicles that year[1]. A base surface is defined as a configuration ending with an abrupt cutoff by a flat or near flat surface [2]. The region immediately following the base surface is a volume that is of very low flow pressure and momentum, caused by this abrupt cut off. These characteristics make the base region a large source of drag, known as base drag. In fact, base drag is responsible for approximately 30% of all of the aerodynamic drag of a truck [2].

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mentioning

confidence: 99%

Bluff Body Drag Reduction Using Passive Flow Control of Jet Boat Tail

Hirst

Yang

et al. 2015

SAE Int. J. Commer. Veh.

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“…Recently, a jet boat tail (JBT) flow control concept developed by Zha 24 have been successfully applied to reduce the air drag of automotive side-view mirror. 21,25 The drag reduction is achieved by forming a boat tail effect that entrains the free stream flow to the base area. The jet surrounding the base surface energizes the base flow, which increase the base pressure, and thus achieves the drag reduction.…”

Section: Introductionmentioning

confidence: 99%

“…Falchi et al 20 experimentally and numerically investigated flow control on rounded edged bluff bodies using a passive ventilation technique. However, little attention 21 has been paid to controlling the flow field around the vehicle door mirror, which is a typical 3D bluff body. Fujimoto and Rinoshika 22 proposed an asymmetric door mirror shape for generating an aerodynamic downforce to increase the vehicle stability.…”

Section: Introductionmentioning

confidence: 99%

Wake flow modification of vehicle external door mirror with slots

Zheng

Zhang

Rinoshika

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part D:

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A passive flow control method is applied to a vehicle external door mirror by introducing flow from a slot drilling from the front surface to four slots around the rear surface. The wake flow fields behind the door mirror and slotted door mirror are experimentally investigated via particle image velocimetry measurements at a Reynolds number of 12,736. The time-averaged flow fields suggest that the reverse-flow region of the slotted door mirror is reduced and pushed downstream; correspondingly, the turbulent kinetic energy of the slotted door mirror is reduced, implying the suppression of unsteadiness and a reduction in the drag force acting on the door mirror. As a result of the jet flow, the wake flow of the slotted door mirror exhibits a weaker spatial correlation and a smaller length scale, indicating the suppression of large-scale vortex shedding and the enhancement of small-scale flow motion by the slots. The jet flows from the left and right slots of the slotted door mirror prevent the upper and lower shear layers from interacting with each other, which promotes symmetric vortex shedding in the near-wake region. The power spectral density and modal energy distributions suggest that the strength of the primary vortex shedding is reduced by the slotted door mirror. The spatial patterns of the first two proper orthogonal decomposition modes suggest that the jet flow distorts the dominant large-scale structure, reducing the strength of the flow oscillation behind the slotted door mirror. The spatial distributions of modes 3 and 4 suggest that the symmetric vortex shedding is enhanced by the jet flow from the slotted door mirror.

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“…The most used and oldest drag reduction methods are passive flow control methods and do not consume external energy. Wang et.al [1] presented the novel drag reduction method for automotive mirrors using passive jet flow control. This method found to be effective both wind tunnel testing with PIV and CFD large eddy simulation (LES) calculation.…”

Section: Introductionmentioning

confidence: 99%

A Comparative CFD Study of Side-view Mirror and Side-view Camera Usages on a City Bus

İpci

2020

International Journal of Automotive Science and Technology

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In this study, the effects of classical side mirrors and side-view cameras on the aerodynamic drag coefficient of a city bus model were investigated with Computational Fluid Dynamics (CFD). The surface profile of 1/5 scale bus was modeled with CATIA v5 program. Aerodynamic analyzes were per-formed with ANSYS Fluent® v18. Reynolds Average Navier-Stokes (RANS)-based Reynolds Stress Model (RSM) was used as the turbulence model. The ground effect was taken into consideration in all analyzes. The solution do-main for 5% blockage ratio was created. Inflation layers are used on the ve-hicle surface regarding velocity changes due to viscous effects. The mesh number independence of analyzes was examined for the bus model without side mirrors and provided for 1.3 M mesh element. The Reynolds number in-dependence of the analysis was investigated by using the optimum number of mesh. Free flow velocity of 90 m/s and above were found to be adequate for Reynolds number independence. The drag coefficient was calculated for the bus with side mirrors by using optimum mesh and wind speed as well. The drag coefficients for the bus with side mirrors and side view cameras were de-termined 0.53 and 0.521 respectively.

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Low Drag Automotive Mirrors Using Passive Jet Flow Control

Cited by 8 publications

References 9 publications

Bluff Body Drag Reduction Using Passive Flow Control of Jet Boat Tail

Bluff Body Drag Reduction Using Passive Flow Control of Jet Boat Tail

Wake flow modification of vehicle external door mirror with slots

A Comparative CFD Study of Side-view Mirror and Side-view Camera Usages on a City Bus

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