An Assessment of Drag Reduction Devices for Heavy Trucks Using Design of Experiments and Computational Fluid Dynamics

Bayraktar, Ilhan; Landman, Drew; Cary, William K.; Wood, Richard M.; Flamm, Jeffrey D.; Hunter, Craig A.

doi:10.4271/2005-01-3526

Cited by 13 publications

(11 citation statements)

References 8 publications

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“…Both indicate a large area of low pressure acting within 0.5 < z* < 1.1, as well as an isolated region of higher pressure located at a top centreline location (1.3 < z* < 1.35). This topology is well known and agrees with that reported previously (Horrigan et al 2007;Storms et al 2001;Bayraktar et al 2005; (2) McCallen et al 1999;Gutierrez et al 1996) as the result of the recirculating wake structure encompassing a proximate bottom vortex core responsible for the minimum Cp magnitudes identified at z* ≈ 0.7-0.8, and upper recirculating flow impingement, for higher magnitudes adjacent to the top edge [y* ≈ 0, z* ≈ 1.35- (Perry et al 2016;Pavia et al 2017;Castelain et al 2018)]. The former appears subtly more pronounced for the stationary ground case, suggesting a stronger influence.…”

Section: Time-averaged Base Pressure Coefficientssupporting

confidence: 93%

Influence of Rotating Wheels and Moving Ground Use on the Unsteady Wake of a Small-Scale Road Vehicle

Rejniak

Gatto

2020

Flow Turbulence Combust

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New insights into how different ground simulation methods affect road vehicle aerodynamics are presented. Experiments are conducted on a 1/24th-scale model, representative of a Heavy Goods Vehicle, at a Reynolds number, based on width of 2.3 × 10 5. Particular focus lay in characterising differences in unsteady wake development, with mean drag, base pressures, and wake velocities quantified, compared, and evaluated. Distinctly, these tests include the effects of elevated blockage ratio and wheel rotation. Results show moving ground use can have a substantial influence under these conditions, with increases in wake length and average base pressure coefficient of 17% and 9%, respectively. The dominant wake dynamics, characterised by a global streamwise oscillation commonly referenced as the bubble pumping mode, was also found dependent with asymmetric shedding frequencies from both vertical and horizontal base edges higher with static ground use. For these conditions, development of a low-frequency turbulence source, near omni-directional in nature, positioned behind the model, further contaminates the flow-field. This feature disappears with moving ground use. Both the nature and characteristics of the turbulence generated behind the wheels were also found to evolve differently, with a moving ground promoting stronger and more defined oscillatory behaviour up to model mid-height, two-and-a-half widths downstream. Overall, these results highlight that while variations in time-independent quantities to differing ground simulation can often be very subtle, prompting the interpretation of negligible overall effects, in-depth consideration from a time-dependent perspective may lead to a different conclusion.

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Section: Time-averaged Base Pressure Coefficientssupporting

confidence: 93%

Influence of Rotating Wheels and Moving Ground Use on the Unsteady Wake of a Small-Scale Road Vehicle

Rejniak

Gatto

2020

Flow Turbulence Combust

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“…In each case, all variations lie within experimental uncertainty indicating insensitivity to support configuration for these test conditions. Overall, the results presented inFigure 5indicate the front mounting to have little influence on the base pressure distribution, showing trends in general agreement with the literature 28,53,[63][64][65][66][67][68][69].…”

supporting

confidence: 87%

“…Maximum Cp is shown close to the top trailing edge, with magnitudes decreasing to a minimum at lower base locations. This topology is typical to this model type 28,63–67 and corresponds to regions dictated by the upper-recirculating flow impingement and lower wake vortex core proximity, respectively. 53,68,69 The former appears slightly more pronounced in Figure 5(a)(iii) (side), with Figure 5(a)(iv) indicating a localised increase of ΔCp ≈ 0.007 at z* ≈ 1.36 relative to Figure 5(a)(i).…”

Section: Resultsmentioning

confidence: 88%

Upstream wind tunnel model mounting: The forgotten method for road vehicle aerodynamics

Rejniak

Gatto

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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A new method for supporting ground vehicle wind tunnel models is proposed. The technique employs a centrally mounted sting connecting the front face of the vehicle, adjacent to the floor, to a fixed point further upstream. Experiments were conducted on a 1/24th-scale model, representative of a Heavy Goods Vehicle, at a width-based Reynolds number of 2.3 × 105, with detailed comparisons made to more established support methodologies. Changes to mean drag coefficients, base pressures and wake velocities are all evaluated and assessed from both time-independent and time-dependent perspectives, with a particular focus within the wake region. Results show subtle changes in drag coefficient, together with discrete modifications to the flow-field, dependent on the method adopted. Subtle differences in base pressures and wake formation are also identified, with mounting the model upstream found to demonstrate retention of many of the beneficial effects of other techniques without suffering their deficiencies. Overall, these results identify the upstream mounting methodology as a viable alternative to currently available and more well-established techniques used to facilitate wind tunnel aerodynamic interrogation.

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“…A survey of the literature shows that the tendency over the years has been to decrease the aerodynamic torsor, particularly the drag force (Modi et al, 1995;Mohamed-Kassim and Filippone, 2010;Jacobsen, 2006;Watkins et al, 1993;Gillié ron and Chometon, 2001). This decrease has been almost 33%, but beyond this further improvement has been difficult (Lanser et al, 1991;Gupta and Ruffin, 1997;Kee et al, 2001;Bayraktar et al, 2005;Wood, 2008) and a challenge to car manufacturers.…”

Section: Introductionmentioning

confidence: 94%

Some innovative concepts for car drag reduction: A parametric analysis of aerodynamic forces on a simplified body

Khaled

Hage

Harambat

et al. 2012

Journal of Wind Engineering and Industrial Aerodynamics

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An Assessment of Drag Reduction Devices for Heavy Trucks Using Design of Experiments and Computational Fluid Dynamics

Cited by 13 publications

References 8 publications

Influence of Rotating Wheels and Moving Ground Use on the Unsteady Wake of a Small-Scale Road Vehicle

Influence of Rotating Wheels and Moving Ground Use on the Unsteady Wake of a Small-Scale Road Vehicle

Upstream wind tunnel model mounting: The forgotten method for road vehicle aerodynamics

Some innovative concepts for car drag reduction: A parametric analysis of aerodynamic forces on a simplified body

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