Flow Seperation and Passive Flow Control on E387 Airfoil

Heffron, Andrew P.; Williams, John; Avital, Eldad

doi:10.2514/6.2016-0324

Cited by 5 publications

(4 citation statements)

References 11 publications

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“…In the following work, vortex circulation is used instead of a change in the boundary layer shape factor to evaluate the effectiveness of a MVG. Based on prior published research [11,24] that found the vortex had the strongest interaction with the wall at of x/h = 10, the vortex circulation was evaluated at this downstream point. Therefore, the efficiency of a MVG in this paper is equal to the ratio of the vortex circulation at x/h = 10 to the drag of the MVG vane.…”

Section: B Mvg Efficiencymentioning

confidence: 99%

Numerical and Experimental Study of Microvortex Generators

Heffron

Williams

Avital

2018

Journal of Aircraft

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A series of experimental and computational studies was conducted on vane-type microvortex generators (MVG) with the aim of better understanding the behaviour and to improve the design of such devices. The traditional rectangular and triangular vanes along with unique NACA0012 and E423 airfoils shaped vanes were studied with a height of 0.2δ while being embedded in a turbulent boundary layer of a flat plate. To assess the reliability of the numerical prediction of the drag forces acting on a MVG, a wind tunnel experiment was conducted. The experiment was conducted at a Reynolds number of 155, based on the friction velocity and the MVG height. A very good agreement was found between the experimental and numerical drag predictions for the MVGs with strong vortices. Fair agreement was found for the two MVGs with weak vortices. From the four-specified vane-type MVGs, the best performing MVG configuration was sought by looking at the ratio of the vortex's circulation strength to the drag of the MVG vanes. It was found that triangular vanes had the best ratio and NACA0012 shaped vanes had the second best ratio. With altercation of the vane angle, vanes placed at angles of 18˚ to 20˚ had the best ratio. To supplement the performance study, the effect of the Reynolds number on the MVGs was also considered. A rectangular MVG vane was modelled at Reynolds numbers of 90 to 1150. A logarithmic relation was found between the Reynolds number of the MVG and the generated vortex's circulation and the drag of the MVG.

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Section: B Mvg Efficiencymentioning

confidence: 99%

Numerical and Experimental Study of Microvortex Generators

Heffron

Williams

Avital

2018

Journal of Aircraft

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“…They observed that flow control with an oscillating micro-cylinder was better than the static one. Heffron et al [16] observed the effect of MVG vane on control flow over the E387 airfoil. The investigation of trip strips was implemented to observe flow separation [17].…”

Section: Introductionmentioning

confidence: 99%

Passive Flow Control of Ahmed Body using Control Rod

Şumnu

2022

Int. J. Automot. Mech. Eng.

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In the current study, numerical analysis of passive control flow with a control rod for Ahmed body is performed at different slant angles and velocities and placed rod locations on the slant surface. The aim of the study is to improve aerodynamic performance by preventing flow separation on the slant surface of Ahmed body using a control rod. This passive flow control method uses a control rod that has not been applied for simplified ground vehicles before. Therefore, it can be said that this study is a new example in point of a passive flow control application for Ahmed body. The solution of the study is performed by using the Computational Fluid Dynamics (CFD) method. The solutions are firstly performed for baseline geometry, and the results are compared with experimental data reported in the literature for validation. CFD solutions are carried out by means of the ANSYS and RNG k- turbulence model is used to simulate flow-field since it captures the effect of turbulent flow. The solutions used a control rod with a 20 mm diameter performed at a dimensionless location (X/L=0.057 and 0.153) for Ahmed body. The results are presented visually in the figures, and drag coefficient values are also given in Table format. It is concluded that the rod application is useful for some specified slant angles and velocities since flow separation delays and suppresses the slant surface. The maximum drag reduction is achieved at about 6.153% at a slant angle of 35° and 20 m/s velocity of air, and location of control rod of 0.057, while the minimum drag reduction is about 1.048% at slant angle of 25° and velocity of air at 40 m/s and location of control rod of 0.153.

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“…Work by Ashill et al [11,12], Allan et al [13], and Wik et al [14] [8,15,16] or detailed experimental measurements [7,9,10,17] but have primarily focused on the downstream behavior of vortex and/or the global performance of the devices. This paper seeks to study the flow behavior directly on the MVG when embedded in a TBL and how it influences the downstream behavior of the vortex.…”

Section: Introductionmentioning

confidence: 99%

Large Eddy Simulation of Microvortex Generators in a Turbulent Boundary Layer

Heffron

Williams

Avital

2021

Journal of Fluids Engineering

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The present study investigates the flow physics on MicroVortex Generators (MVGs) in order to improve their performance in turbulent boundary layers (TBLs). TBLs can be a challenging environment for MVGs because of the streamwise length of the shedded vortex and its increased parasitic drag. Large-Eddy Simulation (LES) is used to properly resolve the turbulent boundary layer of a flat-plate with a zero-pressure gradient and MVG vane. Three different vane-types are investigated (e423-Mod, triangular, and rectangular vanes) in a single vane configuration. Important flow features such as a separation bubble on the leading edge of the rectangular vanes which introduced unsteadiness into the vortex formation and degraded the MVG's efficiency was observed. The e423-Mod and triangular vanes was observed to be more aerodynamically efficient. The triangular vane was found to be the most efficient when evaluated immediately downstream of the vane. However, the vortex from the triangular vane decayed very rapidly due to it being formed very close to the wall which degraded its efficiency further downstream. The e423-Mod vane avoided this problem but its drag was very high relative to the strength of the generated vortex and its vortex experienced a brief period of rapid decay immediately downstream decreasing its efficiency. Further downstream, the vortex of the rectangular vane at 16° became the most efficient through a combination of low vane drag and low vortex decay in the TBL, demonstrating the need to consider a range of issues when designing an MVG.

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Flow Seperation and Passive Flow Control on E387 Airfoil

Cited by 5 publications

References 11 publications

Numerical and Experimental Study of Microvortex Generators

Numerical and Experimental Study of Microvortex Generators

Passive Flow Control of Ahmed Body using Control Rod

Large Eddy Simulation of Microvortex Generators in a Turbulent Boundary Layer

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