Register for free to
view the full innovation profile.
Brunel University London has successfully evaluated a novel Non-Linear Boat tail design which show significant drag reductions for HGVs resulting in improved fuel consumption, while minimising losses in internal space
About
Heavy goods vehicles make a significant contribution to greenhouse gas emissions within the UK and globally. At highway speeds, 50-65% of the useable engine power of a HGV is used to overcome aerodynamic drag. More than 90% of this drag is pressure drag where large differential pressures are setup between the forward and rearward faces of the vehicle. This characteristic of a HGV is the result of a design philosophy aimed at maximising function, where load-carrying capacity and income generation is the main focus, rather than fuel efficiency. With increasingly strict targets being set on transport emissions however, new and improved drag reduction technologies and techniques are needed now more than ever.
Brunel has worked with a HGV trailer manufacturer to demonstrate the feasibility of new and novel non-linear boat-tail (NLBT) design concept as a means for reducing drag of a Heavy Goods Vehicle (HGV). This concept used a unique arrangement of faceted surfaces to enable greater operator performance, improved damage tolerance with minimal impact to payload capacity. Experimental testing of a 1/10th-scale HGV model in a wind tunnel under varied test conditions and configurations identified up to a maximum 8% drag reduction in the optimal configuration. This result represented a possible fuel reduction of 4% with cost and CO2 savings estimated at £3,360 and 4.4 tonnes per vehicle per year. Ultimately, a marginally smaller benefit (5%) from a less optimal configuration was chosen for adoption within the full-scale design exercise as integration within the existing trailer structure was less complicated and represented best value for money (fewer changes to only five components required). This modification reduced the available benefits marginally to £2100 and 2.7 tonnes per vehicle per year respectively.
Key Benefits
An assessment of probable financial benefit and possible impact on a typical single operational HGV carrying a standard 25 tonne payload travelling on average 120,000 km per year was carried out. If fuel use is assumed to be 35 litres for every 100 kilometres, these parameters equate to a total cost for diesel of £84k per year (average price £2/litre). If we also assume maximum NLBT benefits are realised (8% drag reduction providing a 4% reduction in fuel consumption) this provides yearly cost savings of £3360/vehicle. If using the more targeted and conservative 5% drag reduction goal selected for the full-scale integration redesign, £2100/vehicle/year is realised. Both these figures represent a non-trivial benefit to the industrial partner as a manufacturer, given the relative ease for which the redesign can be implemented for the latter. With a future intent to adopt this technology on an initial tranche of 50 vehicles, total fuel cost savings are expected to equal £105k in the first year alone for an operator.
Applications
The Heavy Goods Vehicle market is worth globally in excess of 200 billion currently with expectations for this to rise to over 300 billion by 2027. Given the size of this market, both manufacturers and operators exist in a competitive environment where fitness for purpose, practicality and maximising returns is of paramount importance. As such, any modification or change to improve the aerodynamics must be considered in unison with the need to maintain simplicity of manufacture, minimise assembly times and maintenance costs, all while ensuring no significant impact on payload carrying capacity. Damage tolerance is also a critical consideration as minor damage events from day-to-day operations are likely during the lifespan of the trailer. The non-linear boat-tail concept outlined in this report meets all these requirements.