An experimental characterisation of the wake of a detailed heavy vehicle in cross-wind. Issue 175 (April 2018)

• Record Type: Journal Article
• Authors: McArthur, Damien; Burton, David; Thompson, Mark; Sheridan, John
• Is Part Of: Journal of wind engineering and industrial aerodynamics. Issue 175(2018)
• Page Start: 364
• Page End: 375
• Publication Date: 2018-04
• Subjects: Bluff body -- Wake -- Heavy vehicle -- Aerodynamics -- Square back -- Truck -- Yaw -- Cross-wind; Wind-pressure -- Periodicals; Buildings -- Aerodynamics -- Periodicals; Pression du vent -- Périodiques; Constructions -- Aérodynamique -- Périodiques; Buildings -- Aerodynamics; Wind-pressure; Periodicals
• DOI: 10.1016/j.jweia.2018.01.033
• Languages: English
• ISSNs: 0167-6105

Abstract

Abstract: The unsteady wakes associated with detailed heavy vehicles with different levels of passive aerodynamic treatment are investigated in a wind tunnel using a 1/3 scale model. Drag coefficient, base pressure and wake total pressure are measured for detailed vehicles at yaw angles up to 15° for six semi-trailer vehicle configurations. Cabin extenders and side-skirts were shown to be more effective at reducing drag under yawed flow conditions, while certain front-end modifications were found to perform best at ψ = 0 ∘ when the tractor was more able to shield the trailer from oncoming flow. Base pressure was shown to reduce with yaw angle, with the low pressure signature of the main lower vortex tilting upwards on the leeward side of the vehicle's base. Total pressure grid measurements showed two different types of wake, those where the stream-wise vortex formed by flow separating off the roof of the trailer is separated from the bulk vehicle wake by a region of high total pressure, and those where the two are indistinguishable. Vehicles without a distinct trailing vortex in this region were found to exhibit stronger horizontal asymmetries in their base pressure profiles. Highlights: Transient base pressure and wake total pressure measurements are presented for various detailed heavy vehicles at yaw. It is demonstrated that changes to base pressure and changes to drag at yaw are not always directly related. Base pressure was reduces with yaw, and low pressure associated with the lower vortex tilts upwards with yaw. Total pressure measurements identify distinct low pressure regions, which were associated with a streamwise vortex. Base pressures PODs show the proportion of fluctuating energy in the first 3 modes decreases with increasing yaw.