Aerodynamics Evaluation of Road Vehicles in Dynamic Maneuvering

Okada, Yoshihiro; Nakashima, Takuji; Tsubokura, Makoto; Morikawa, Yousuke; Kouno, Ryousuke; Okamoto, Shogo; Matsuhiro, Tanaka; Nouzawa, Takahide

doi:10.4271/2016-01-1618

Cited by 3 publications

(6 citation statements)

References 19 publications

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“…The simulations were performed in a rectangular computational domain that was divided into approximately 48 million tetrahedral cells as in our previous simulations 7,8 . The computational domain and grids are shown in Fig.…”

Section: B Computational Conditionsmentioning

confidence: 99%

“…Although these two vehicles showed similar aerodynamic coefficients in wind-tunnel conditions, their high-speed stabilities in a subjective assessment differed 4,5 . We also conducted CFD (Computational Fluid Dynamics) simulations with simplified vehicle models 6 and with more realistic geometries 7,8 to investigate flow phenomena regarding the aerodynamic responses in an on-road experiment 4,5 . The numerical results revealed differences in the flow structure, which is characterized by a flow blowing from the front wheel clearance and its behavior at the side of the vehicle.…”

Section: Introductionmentioning

confidence: 99%

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Aerodynamics Simulation of a Sedan-type Road Vehicle in Cornering Motion with Roll Angle

Kono

Nakashima

Tsubokura

et al. 2016

34th AIAA Applied Aerodynamics Conference

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In this study, an aerodynamics simulation of a road vehicle in a steady-state cornering motion is conducted, and the aerodynamic effects of its postural change in the roll direction are discussed. The numerical results indicated an aerodynamic centrifugal force induced by the roll-on. This aerodynamic effect was decomposed into two causes: a revolution of force direction with a rotation of the vehicle's body, and a change in aerodynamic force distribution on the vehicle's body according to changes in flow structures around the vehicle. From a quantitative evaluation, neither factor is negligible in the aerodynamics of the vehicle during steady-state cornering. The side force distribution in the vehicle's longitudinal direction, the pressure changes on the vehicle's body, and the total pressure distributions around the vehicle were visualized, and aerodynamic phenomena were discussed. The changes in flow caused by roll variations were observed mainly around the front wheels. Nomenclature  = Slip angle of a vehicle C S = Aerodynamic side force coefficient CS,flow = Aerodynamic side force coefficient induced by a change in flow phenomena CS,lift = Aerodynamic side force coefficient apparently changed by a rotation of lift and side forces C L = Aerodynamic lift force coefficient C pt = Total pressure coefficient CYM = Aerodynamic yaw moment coefficient CS,flow = Aerodynamic yaw moment coefficient induced by a change in flow phenomena C YM,pitch = Aerodynamic yaw moment coefficient apparently changed by a rotation of pitch and yaw moments C = Variation of aerodynamic coefficient C caused by a cornering motion G = Roll stiffness of a road vehicle 2  = Roll angle of vehicle M = Sprung mass of vehicle r = Yaw rate (yaw angular velocity) r' = Nondimensional yaw rate; r' = r / (U/L) U = Running velocity of vehicle u = Forward speed (longitudinal velocity of vehicle); u = U cos v = Slip speed (lateral velocity of vehicle); v = U sin wr,wor = Valuable in cases with and without roll angle

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Section: B Computational Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aerodynamics Simulation of a Sedan-type Road Vehicle in Cornering Motion with Roll Angle

Kono

Nakashima

Tsubokura

et al. 2016

34th AIAA Applied Aerodynamics Conference

Self Cite

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“…Moreover, vehicle motion, which is another type of on-road disturbance, also affects the aerodynamics. As a typical vehicle motion on a road, the effects of a cornering motion on the aerodynamics have been investigated [12][13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…Josefsson et al [14] conducted a steady Reynolds-averaged Navier-Stokes (RANS) simulation of a sedan-type vehicle during steady-state cornering and indicated that the asymmetric geometry of the underbody affected the drag increase due to the cornering motion. Tsubokura et al [15] and Okada et al [16] numerically investigated the unsteady aerodynamic characteristics of a sedan-type vehicle during meandering motion, focusing on the responses of the side force and yaw moment in relation to the drivability of the automobile. These researchers adopted special numerical techniques using non-inertial reference frame and modified boundary condition [17] for vehicle aerodynamics to reproduce the cornering motion.…”

Section: Introductionmentioning

confidence: 99%

“…These researchers adopted special numerical techniques using non-inertial reference frame and modified boundary condition [17] for vehicle aerodynamics to reproduce the cornering motion. However, they investigated the cornering effects on the aerodynamics for a specific vehicle geometry, with the shape variation in the research limited to details of the body shape [14] or aerodynamic parts [15,16]. To understand the effects more universally, it would be effective to investigate the effects on vehicles with different fundamental aerodynamic characteristics under the same cornering condition.…”

Section: Introductionmentioning

confidence: 99%

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Fluid-Dynamic Force Measurement of Ahmed Model in Steady-State Cornering

et al. 2020

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The effects of on-road disturbances on the aerodynamic drag are attracting attention in order to accurately evaluate the fuel efficiency of an automobile on a road. The present study investigated the effects of cornering motion on automobile aerodynamics, especially focusing on the aerodynamic drag. Using a towing tank facility, measurements of the fluid-dynamic force acting on Ahmed models during steady-state cornering were conducted in water. The investigation included Ahmed models with slant angles θ = 25° and 35°, reproducing the wake structures of two different types of automobiles. The drag increase due to steady-state cornering motion was experimentally measured, and showed good agreement with previous numerical research, with the measurements conducted at a Reynolds number of 6 × 105, based on the model length. The Ahmed model with θ = 35° showed a greater drag increase due to the steady-state cornering motion than that with θ = 25°, and it reached 15% of the total drag at a corner with a radius that was 10 times the vehicle length. The results indicated that the effect of the cornering motion on the automobile aerodynamics would be more important, depending on the type of automobile and its wake characteristics.

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Influence of the Car Movable Aerodynamic Elements on Fast Road Car Cornering

et al. 2022

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In the case of road cars, road safety is the primary factor. The geometry of high-speed road cars has no regulatory restrictions. In addition to the high engine power and effective shape, they can use various types of additional movable aerodynamic elements to adjust their aerodynamic characteristics to the road conditions. Based on the geometry of a two-seater prototype of such a vehicle, a numerical analysis of the influence of a number of additional movable aerodynamic elements on its aerodynamic characteristics was performed. Several of them were installed on the prototype. An electronic system recording a number of motion parameters of the entire car body and some of its movable elements installed on the body was designed and built. The system has been adapted to program the motion of additional aerodynamic elements according to the set algorithms of their activation, temporarily changing the aerodynamic characteristics of the car. An experimental study of the effect of changes in the aerodynamic characteristics of the prototype on its dynamic properties during a drive through a test road section was carried out. It was shown to what extent an average driver can increase the safe speed of the curve of the road using the possibilities of moving aerodynamic elements installed on it.

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Aerodynamics Evaluation of Road Vehicles in Dynamic Maneuvering

Cited by 3 publications

References 19 publications

Aerodynamics Simulation of a Sedan-type Road Vehicle in Cornering Motion with Roll Angle

Aerodynamics Simulation of a Sedan-type Road Vehicle in Cornering Motion with Roll Angle

Fluid-Dynamic Force Measurement of Ahmed Model in Steady-State Cornering

Influence of the Car Movable Aerodynamic Elements on Fast Road Car Cornering

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