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

Abstract

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.