Plasma Streamwise Vortex Generators for Flow Separation Control on Trucks

Vernet, Julie A.; Soderblom, David R.; Elofsson, Per; Alfredsson, P. Henrik

doi:10.1007/s10494-018-9891-9

Cited by 27 publications

(11 citation statements)

References 12 publications

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“…In particular, many studies focusing on improvement of wing performance by suppressing the flow separation (Sato et al, 2015;Fujii, 2018) have been conducted in the aerospace field. Regarding applications of PA on automobile flow, aerodynamic noise reduction (Miyamoto et al, 2018) and aerodynamic drag reduction (Shadmani et al, 2018;Kanatani et al, 2009;Vernet et al, 2018) have been studied. These studies aimed to reduce the boundary layer separation from the automobile's body, such as at the roof's end or the rounded pillar, similar to suppressing flow separation on a wing.…”

Section: Aerodynamic Drag Reduction Of a Simplified Vehicle Model By mentioning

confidence: 99%

“…These studies aimed to reduce the boundary layer separation from the automobile's body, such as at the roof's end or the rounded pillar, similar to suppressing flow separation on a wing. Vernet et al (2018) mounted a PA in a U-shape configuration to induce a longitudinal vortex to suppress the flow separation at the rounded pillar surface. Conversely, the aerodynamic drag of an automobile can also be reduced by promoting flow separation on the body surface.…”

Section: Aerodynamic Drag Reduction Of a Simplified Vehicle Model By mentioning

confidence: 99%

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Aerodynamic drag reduction of a simplified vehicle model by promoting flow separation using plasma actuator

Shimizu

Nakashima

Sekimoto

et al. 2019

Mechanical Engineering Letters

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In recent years, the dielectric barrier discharge plasma actuator (DBD-PA), which is a fluid control device, has been investigated for achieving both high aerodynamic performance and pleasing styling of transportation equipment. In this study, the authors installed a DBD-PA system on a simplified three-dimensional bluff automobile body to reduce the aerodynamic drag. In particular, the authors focused on the sides of the rear end of the body, where the local shape has high sensitivity regarding both styling and aerodynamic drag. At the rear sides of the automobile-like bluff body, a sharp edge rather than a smooth rounded corner often reduces the aerodynamic drag by promoting airflow separation. Therefore, the authors aimed to reduce the aerodynamic drag by using a DBD-PA system to promote flow separation at the rear end while retaining its rounded shape. Aerodynamic measurements using a one-fifth scale simplified automobile model were conducted in a wind tunnel. Preliminary investigation of the aerodynamic effect at the rear clarified how the longitudinal vortices from the rear pillar and the side edge of the trunk deck cause the drag increase at the rear-end corners. Two parallel DBD-PAs were installed on the rear surface to shift these vortices away from the corners by promoting flow separation. The drag reduction rate reached 3% at the highest applied voltage using the DBD-PA system on a rounded shape, and it achieved approximately half the effect of the sharp-edged shape. The longitudinal vortices were successfully kept away from the rear-end corners by the DBD-PAs. The surface pressure increased with the displacement of the vortices, which led to the drag reduction observed.

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Section: Aerodynamic Drag Reduction Of a Simplified Vehicle Model By mentioning

confidence: 99%

Section: Aerodynamic Drag Reduction Of a Simplified Vehicle Model By mentioning

confidence: 99%

Aerodynamic drag reduction of a simplified vehicle model by promoting flow separation using plasma actuator

Shimizu

Nakashima

Sekimoto

et al. 2019

Mechanical Engineering Letters

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“…24 presumably saturates because h should be longer for larger airspeeds. Similar considerations about scaling the size of the actuators has been done also in other studies applied to ground vehicles [38]. At present the scaling problem is open, and recently an attempt to follow these design rules at larger airspeeds has been done by testing a multi-tip DBD of larger size with encouraging results up to 35 m/s [37].…”

Section: Discussionmentioning

confidence: 67%

Separation Control by Plasma Actuators: Effects of Direct Momentum Injection and Vortex Generation

Messanelli¹,

Frigerio²,

Tescaroli

et al. 2019

Flow Turbulence Combust

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In this work, Dielectric Barrier Discharge actuators with triangular tips on their exposed electrodes are applied on a NACA 0015 airfoil and tested in the wind tunnel at an airspeed of 20 m/s (Re=330k); the actuator set has been defined after previous laboratory studies. Steady and pulsed actuation are tested on all devices, including a straight DBD as reference. Force coefficients and electrical power are measured for every actuator, evaluating their performance in terms of aerodynamic coefficients changes with respect to the smooth airfoil and to the unpowered case, which is also characterized by means of surface visualizations. The influence of discharge length and tip spacing is studied by image processing techniques. The local field of motion is characterized by means of boundary layer velocity profiles, acquired with plasma off and on. Boundary layer thickness and momentum coefficients are determined at different spanwise locations for all the devices. The results are discussed evaluating the different impacts of streamwise momentum injection and vortex generation on the actuators performance, assuming these mechanisms as proper models for the data interpretation. In turn, this leads to outline possible design rules for this kind of DBD. Keywords Separation control • Plasma actuators • Dielectric Barrier Discharge 1 IntroductionIn the research field of flow control, the dielectric barrier discharge (DBD) actuators have been extensively studied in the last years, and many DBD actuators have reached the technology readiness level for possible applications in low speed aerodynamics. The performance of a classic surface DBD depends on electrical and geometrical parameters, such as waveform, frequency and amplitude of the applied voltage, electrodes gap, material and thickness of the dielectric [1,2]. In particular, the shape of the exposed electrode can have a strong influence on the intensity and the direction of the induced ionic wind, exploiting different kinds of flow control. Different spanwise-periodic shapes, such as serpentine, square-wave [3,4] and serrated edge [2,5,6] have been studied both numerically and in the laboratory. These configurations induce streamwise and transverse ionic wind at the same time, so they can energize a boundary layer in different ways, by direct streamwise acceleration and by creating a 3D flow in the near field that gives rise to streamwise vortex structures. In turn, these vortices mix the high-speed external flow with the

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“…They suggested that by increasing the plasma voltage, the drag reduction in high velocities can be improved. Vernet et al 39 conducted wind-tunnel experiments to control the flow separation around a truck under cross-wind conditions using DBD plasma actuators, and could obtain up to 20% drag reduction for the largest yaw angle.…”

Section: Introductionmentioning

confidence: 99%

Drag reduction of 3D bluff body using SDBD plasma actuators

Kazemi

Ghanooni

Mani

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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In the current research, a series of different combinations of plasma SDBD actuators mounted on a simplified road vehicle have been experimentally studied to find the optimum position of the actuators for controlling the flow separation and reducing the vehicle form drag. Separation point of the flow over the rear ramp, large trailing vortices of the standard model, and laminar separation bubble (LSB) of the rear ramp leading edge are among the most significant factors to be controlled. The experiments were conducted at Reynolds numbers ranging from 0.55 × 106 to 1.11 × 106 in a subsonic wind tunnel while the pressure distribution over the model and its streamwise force balance were accurately measured. Significant drag reduction due to the use of DBD actuators was observed. As such, for the range of tested Reynolds numbers, a maximum of 25.1% of drag reduction in the vehicle drag coefficient could be achieved. The optimum combinations of activation voltages (6, 9, and 12 kV) and wave frequencies (6, 10, and 14 kHz) for plasma actuators were also found. Furthermore, it was observed that SDBD actuators mounted on the rear ramp of the model had a deeper impact on the vehicle drag coefficient compared to the other actuators.

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Plasma Streamwise Vortex Generators for Flow Separation Control on Trucks

Cited by 27 publications

References 12 publications

Aerodynamic drag reduction of a simplified vehicle model by promoting flow separation using plasma actuator

Aerodynamic drag reduction of a simplified vehicle model by promoting flow separation using plasma actuator

Separation Control by Plasma Actuators: Effects of Direct Momentum Injection and Vortex Generation

Drag reduction of 3D bluff body using SDBD plasma actuators

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