The aerodynamic interaction of platooning and overtaking vehicles

The development of innovative autonomous vehicles (AV) with increased efficiency and low carbon emissions is of interest to many different organisations across the world, at both political, commercial and research levels. Economically benefits are estimated to be worth £1.5 trillion by 2025. Recognising the potential, transportation authorities are already investing heavily in studies to exploit these innovative technologies through the development of 'platooning' methods, whereby a series of vehicles run in close formation, exploiting potential energy savings created through a reduction in drag, further enabling greater mobility. In the immediate future, it is likely the freight haulage industry will be the first users to introduce autonomous technologies on a network-wide scale. The UK road network provides the ideal test bed for developing these innovative technologies, due to the complexities of adopting such systems within a highly congested network, with traffic moving at variable speeds. Ensuring AVs and platooning methods are appropriate for challenging transport systems, such as that in the UK, will enable these systems to be adopted on an international scale more easily.

To date, most AV research has focused on ensuring the technical possibilities for vehicles travelling in close formation through the implementation of autonomous guidance systems. These factors are however only one area of consideration when introducing new operational methods that involve complex vehicle interactions into an already a complex transport mode. Fundamental research undertaken at the University of Birmingham (UoB) (EP/N004213/1) has shown that aerodynamic forces will, in many cases, be the governing design parameter. There is a need to understand and correctly account for the highly turbulent aerodynamic flow created around platoons and unsteady forces leading to vehicle instabilities and dangerous conditions for other road users.

This proposal is concerned with the technical area of vehicle aerodynamics associated with close running vehicles and the aerodynamic interactions with other vehicles and road users. In particular the following aspects will be investigated:
-Overall stability of close formation vehicles (Heavy Goods Vehicles (HGVs)), particularly the interaction of unsteady aerodynamic flows between platooning vehicles and other road users.
-The aerodynamic implications in terms of stability and overall drag for vehicles moving out of alignment with other vehicles in a platoon and the interaction of overtaking vehicles.
-The aerodynamic interaction of a passing platoon of HGVs with other road users leading to potential stability and safety issues.

The fundamental research questions will be addressed by novel approaches:
-A fundamental physical modelling programme at the UoB moving model TRAIN rig facility. Detailed measurement of vehicle surface pressure (such that aerodynamic forces can be calculated) will determine the nature of the flow field and the aerodynamic interaction of vehicles. Multi-hole pressure probe measurements will investigate the unsteady flow to determine potential stability and safety implications as a platoon passes.
-Development of an analytical framework, providing a method to help industry assess the magnitude of aerodynamic loads on roadside workers and other road users.

The current study is seen as a necessary precursor to the introduction of AV technologies. In depth understanding of these practical issues underpins the safe, timely and cost effective implementation of these new technologies. This project will, for the first time, address these issues, developing an understanding of aerodynamic effects, not only for platooning vehicles but also other road users interacting with the platoon on public transport systems. The national importance of AVs forms an integral part of the Government strategic vision for transport and is of considerable importance to a variety of stakeholders.