Drag Reduction on the 25-deg Ahmed Model Using Fluidic Oscillators

Metka, Matthew; Gregory, James W.

doi:10.1115/1.4029535

Cited by 61 publications

(23 citation statements)

References 11 publications

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“…Corresponding research was carried out at different positions, and various kinds of drag-reducing devices have been introduced to effectively decrease the aerodynamic drag of tractor-trailers, including their cab roofs or gap fairings [11][12][13][14], their side skirts [15], their base flaps [16], and their boat tails [17,18]. Some studies focused on their aerodynamic characteristics, using a combination of various devices and interactions with the actual complex shape of tractortrailers [19,20]. Previous studies mostly focused on performance optimizations using aerodynamic drag reduction devices.…”

Section: Introductionmentioning

confidence: 99%

Research on the Aerodynamic Characteristics of Tractor-Trailers with a Parametric Cab Design

et al. 2018

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As tractor-trailer ownership has increased year-by-year, corresponding energy consumption and environmental issues have gradually become a heated issue. Approximately 45 percent of the total aerodynamic drag of tractor-trailers is attributed to the flow at the front surface of the cab, and the gap between the cab and trailer. Therefore, this study has taken a new approach to designing the shape of the cab inspired by the external forebody of the cheetah. A parametric design protruding cab was devised in this study; the length of the protruding part and the angle between this protruding part and the A pillar were two design variables. Computational fluid dynamics simulation was conducted to investigate the drag reduction effects of these new cab styling designs, and the proposed cab reduced the drag by a maximum of 8.49%. The flow characteristics around the whole body of the tractor-trailer baseline model and the parametric cab design vehicle model were analyzed using the velocity streamline graph to illuminate the change of the flow field and the drag-reduction mechanism of the proposed design. A vortex formed above the protruding part of the cab and it acted as a 'vortex cushion' to accelerate the speed of the air flow; accordingly, the positive and negative pressure distribution on the front surface of the cab and trailer also changed. The new parametric design has provided the possibility to adjust the forebody of the cab to an aerodynamically optimized shape, and these findings have offered useful information for the development of a new design method of the tractor-trailer to reduce aerodynamic drag and improve fuel economy.

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Section: Introductionmentioning

confidence: 99%

Research on the Aerodynamic Characteristics of Tractor-Trailers with a Parametric Cab Design

et al. 2018

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“…The key concept of active flow control is to achieve effective separation flow control by directly injecting momentum into the boundary layer and changing or overcoming the adverse pressure gradient. Common momentum injection methods include mixed jets [3], pulse jets [4,5], fluidic oscillators [6], and surface dielectric barrier discharge (SDBD) plasma actuators [7,8]. Compared with mechanical synthetic jets, an SDBD plasma actuator is a new type of active flow control device.…”

Section: Introductionmentioning

confidence: 99%

Separation Flow Control of a Generic Ground Vehicle Using an SDBD Plasma Actuator

Zheng

Guo

et al. 2019

Energies

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Quiescent flow and wind tunnel tests were performed to gain additional physical insights into flow control for automotive aerodynamics using surface dielectric barrier discharge plasma actuators. First, the aerodynamic characteristics of ionic wind were studied, and a maximum induced velocity of 3.3 m/s was achieved at an excitation voltage of 17 kV. Then, the optimal installation position of the actuator and the influence of the excitation voltage on flow control at different wind speeds were studied. The conclusions drawn are as follows. The effect of flow control is better when the upper electrode of the actuator is placed at the end of the top surface, increasing the likelihood of the plasma generation region approaching the natural separation location. The pressure on top of the slanted surface is primarily affected by airflow acceleration at a low excitation voltage and by the decrease of the separation zone at a high excitation voltage. The maximum drag reduction can be realized when the maximum velocity of ionic wind reaches 1.71 m/s at a wind speed of 10 m/s and 2.54 m/s at a wind speed of 15 m/s. Moreover, effective drag reduction can be achieved only by continuing to optimize the actuator to generate considerable thrust at a high wind speed.

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“…One of the drawbacks of these methods is that they have uncontrolled performance for various conditions (Kourta et al 2012). On the other hand, active control methods such as mixed jets (Kourta et al 2012), pulse jets (Joseph et al 2012) and fluidic oscillators (Metka et al 2015) have been investigated. Controllable nature of these methods allow them to be turned on/off on demand.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Flow Control over an Ahmed Body using DBD Plasma Actuator

Shadmani

Nainiyan

Mirzaei

et al. 2018

JAFM

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Ahmed body is a standard configuration of road vehicles and most of the studies of automobile aerodynamics are performed based on it. In this paper, the plasma actuator was used as an active flow control method to control the flow around the rear part of the Ahmed body with the rear slant angle of 25°. Experiments were carried out in a wind tunnel at two different velocities of U=10m/s and U=20m/s using steady and unsteady excitations. The hot-wire anemometer was used to measure the vortex shedding frequency at the downstream of the body. Pressure distribution was measured using 52 sensors and total drag force was extracted with a load cell. Furthermore, smoke flow visualization was employed to investigate the flow pattern around the body. The results showed that the plasma actuator was more effective on the pressure distribution and total drag force at the velocity of U=10m/s. In fact, by applying steady and unsteady excitations there was 7.3% and 5% drag reduction; respectively. While at the velocity of U=20m/s; the actuator had no significant effect on pressure distribution and total drag. As a remarkable result, the plasma actuator, especially in the steady actuation, has demonstrated its effectiveness on dispersing the longitudinal vortices and suppressing the separated flow on the rear slant at low velocities.

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Drag Reduction on the 25-deg Ahmed Model Using Fluidic Oscillators

Cited by 61 publications

References 11 publications

Research on the Aerodynamic Characteristics of Tractor-Trailers with a Parametric Cab Design

Research on the Aerodynamic Characteristics of Tractor-Trailers with a Parametric Cab Design

Separation Flow Control of a Generic Ground Vehicle Using an SDBD Plasma Actuator

Experimental Investigation of Flow Control over an Ahmed Body using DBD Plasma Actuator

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