Influence of Inter-Vehicle Distance on the Aerodynamics of a Two-Truck Platoon

Törnell, Johannes; Sebben, Simone; Soderblom, David R.

doi:10.1007/s12239-021-0068-5

Cited by 11 publications

(5 citation statements)

References 33 publications

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“…Previous studies have shown that this minor infringement on the stringent CFL requirement has no significant effect on the simulations [76][77][78]. The quality of the mesh has been checked by other quantities as well, such as the blending function and the turbulent viscosity ratio, which also confirm that the present mesh meets the requirement of the IDDES model [39]. The numerical model has been validated by comparing it with experimental results (including slipstream properties, surface pressures, and drag coefficients) obtained by Zhang et al [50] and Zhang [79].…”

Section: Mesh Independence and Numerical Validationsupporting

confidence: 72%

Numerical Investigation of The Aerodynamics of Lorry Platooning Travelling through Road Tunnels

Zhang

Soper²,

Fraga³

et al. 2023

Univers. J. Civ. Eng.

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With potential benefits in drag reduction and fuel saving, the aerodynamics of vehicle platoons have been investigated for a wide range of cases in open space. When vehicle platoons travel in road tunnels, the platooning strategy could be affected by the tunnel size, the traffic lane, and the inter-vehicle spacing. This paper presents a detailed investigation of these effects by numerically simulating the aerodynamics of an eight-lorry platoon travelling through road tunnels. The slipstream velocity and pressure fields, flow structures, and drag forces are examined as the inter-vehicle spacing are varied from 0.1L to 1.5L, where L is the length of a single lorry. It is found that the airflow induced by the moving platoon in the large tunnel (two-lane tunnel) is weaker than that in the small tunnel (single-lane tunnel), but similar to the case in the open air. As a result, the drag reduction due to platooning is most significant in the small tunnel, while the results in the large tunnel and the open air are largely identical. It is further found that, owing to the efficient shielding, the drag reduction in the open air increases monotonically as the inter-vehicle spacing decreases. However, the flow fields in both small and large tunnels change pronouncedly when the inter-vehicle spacing is 0.25L, resulting in relatively larger drag coefficients at this spacing. These findings are less sensitive to the traffic lane. This study provides useful insight into the platooning strategy of a long lorry platoon.

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Section: Mesh Independence and Numerical Validationsupporting

confidence: 72%

Numerical Investigation of The Aerodynamics of Lorry Platooning Travelling through Road Tunnels

Zhang

Soper²,

Fraga³

et al. 2023

Univers. J. Civ. Eng.

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“…In practice, the distances of a vehicle to its predecessor and follower both affect the aerodynamic drag coefficient of the vehicle. The platoon with shorter intervehicle distance has less aerodynamic drag force at the same speed [43]. Some studies provided approximately methods to calculate the aerodynamic drag coefficient based on intervehicle distances [44]- [46].…”

Section: The Models For Fuel and Energy Consumptionmentioning

confidence: 99%

Eco-Driving of General Mixed Platoons With CAVs and HDVs

Yang

Zhao

Lan

et al. 2023

IEEE Trans. Intell. Veh.

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Eco-driving has been widely investigated over the last decade, but most studies focused on an individual vehicle or a vehicle platoon consisting of pure connected and automated vehicles (CAVs). Recently, mixed vehicle platoons consisting of both CAVs and human-driven vehicles (HDVs) have attracted much interest, considering the fact that HDVs will mix with CAVs in the traffic system for a long period. This paper proposes an eco-driving strategy for mixed platoons, composing of both offline planning and online tracking. In offline planning, an energy-efficient speed reference and a gearshift reference are determined by using the characteristics of each vehicle and future traffic information through dynamic programming. Offline planning optimised the vehicle speed and gearshift to allow the vehicle powertrain working at a high efficiency region. In online tracking, two different types of model predictive controls (MPCs) are proposed to control the CAVs in real-time. The MPCs are designed to achieve precise speed reference tracking performance and guarantee platoon string stability, respectively. Meanwhile, HDVs within the mixed platoon can be located anywhere in the platoon except working as the first vehicle to improve flexibility. Therefore, the proposed eco-driving strategy is applicable to mixed platoons with more general structures in ordering. The key contribution of this study is that the proposed eco-driving strategy can optimise the total fuel consumption for general mixed platoons. Simulation results show that the proposed ecodriving strategy improves the fuel economy of a mixed platoon by up to 6.39% compared to the benchmark conventional-adaptive cruise control strategies.

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“…This practice, also known as drafting or slipstreaming, is seen quite heavily in automotive racing where racers travel in extremely close proximity, this is done in order to conserve fuel and increase top speed through a reduction in drag. While this practice is less seen in consumer vehicles, among heavy transport vehicles, such as freight liners, the practice is quite popular and can produce great returns in fuel savings [2][3][4], to cite a few. With the rapid advances in self-driving technology it is believed by many that soon even consumer vehicles will begin platooning in a connected transportation system due to the decreasing follow distances that self-driving cars can achieve with their low reaction times and vehicle to vehicle communication [5,6].…”

Section: Introductionmentioning

confidence: 99%

“…Also notable is the work that has been done on HVPs by the likes of Watts et al [2] who used CFD studies to analyze the interactions of tractor trailer platooning as well as the flow around surface mounted cubes in a tandem orientation. This work was followed by works such as Mokhtar [3] who investigated ways of lowering drag through transverse offset between vehicle and Tornell [4] who found that even at a follow distances of 20L the trailing vehicle still saw a large reduction in cooling flow.…”

Section: Introductionmentioning

confidence: 99%

Development of a Numerical Investigation Framework for Ground Vehicle Platooning

Bounds

Rajasekar

Uddin

2021

Fluids

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This paper presents a study on the flow dynamics involving vehicle interactions. In order to do so, this study first explores aerodynamic prediction capabilities of popular turbulence models used in computational fluid dynamics simulations involving tandem objects and thus, ultimately presents a framework for CFD simulations of ground vehicle platooning using a realistic vehicle model, DrivAer. Considering the availability of experimental data, the simulation methodology is first developed using a tandem arrangement of surface-mounted cubes which requires an understanding on the role of turbulence models and the impacts of the associated turbulence model closure coefficients on the prediction veracity. It was observed that the prediction accuracy of the SST k−ω turbulence model can be significantly improved through the use of a combination of modified values for the closure coefficients. Additionally, the initial validation studies reveal the inability of the Unsteady Reynolds-Averaged Navier-Stokes (URANS) approach to resolve the far wake, and its frailty in simulating tandem body interactions. The Improved Delayed Detached Eddy Simulations (IDDES) approach can resolve the wakes with a reasonable accuracy. The validated simulation methodology is then applied to the fastback DrivAer model at different longitudinal spacing. The results show that, as the longitudinal spacing is reduced, the trailing car’s drag is increased while the leading car’s drag is decreased which supports prior explanations of vortex impingement as the reason for drag changes. Additionally, unlike the case of platooning involving Ahmed bodies, the trailing model drag does not return to an isolated state value at a two car-length separation. However, the impact of the resolution of the far wake of a detailed DrivAer model, and its implication on the CFD characterization of vehicle interaction aerodynamics need further investigations.

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Influence of Inter-Vehicle Distance on the Aerodynamics of a Two-Truck Platoon

Cited by 11 publications

References 33 publications

Numerical Investigation of The Aerodynamics of Lorry Platooning Travelling through Road Tunnels

Numerical Investigation of The Aerodynamics of Lorry Platooning Travelling through Road Tunnels

Eco-Driving of General Mixed Platoons With CAVs and HDVs

Development of a Numerical Investigation Framework for Ground Vehicle Platooning

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