scholarly journals Vortex Shedding Suppression: A Review on Modified Bluff Bodies

Eng ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 325-339
Author(s):  
Amir Teimourian ◽  
Hanifa Teimourian
Keyword(s):  
Fluid Dynamics ◽  
Flow Control ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Bluff Bodies ◽  
Experimental Fluid Dynamics ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Unsteady Wake ◽  
Computational Fluid Dynamics Cfd

Vortex shedding phenomenon behind bluff bodies and its destructive unsteady wake can be controlled by employing active and passive flow control methods. In this quest, researchers employed experimental fluid dynamics (EFD), computational fluid dynamics (CFD) and an analytical approach to investigate such phenomena to reach a desired outcome. This study reviews the available literature on the flow control of vortex shedding behind bluff bodies and its destructive wake through the modification of the geometry of the bluff body. Various modifications on the bluff body geometries namely perforated bluff bodies, permeable and porous mesh, corner modification and wavy cylinder have been reviewed. The effectiveness of these methods has been discussed in terms of drag variation, wake structure modifications and Strouhal number alteration.

scholarly journals Microfiber Coating for Flow Control over a Blunt Surface

Coatings ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 664 ◽  
Author(s):  
Mitsugu Hasegawa ◽  
Hirotaka Sakaue
Keyword(s):  
Drag Reduction ◽  
Flow Control ◽  
Bluff Body ◽  
Relative Length ◽  
Control Device ◽  
Cylinder Surface ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Maximum Drag Reduction ◽  
The Impact

A microfiber coating having a hair-like structure is investigated as a passive flow control device of a bluff body. The effect of microfiber length is experimentally studied to understand the impact of the coating on drag on a cylinder. A series of microfiber coatings with different lengths are fabricated using flocking technology and applied to various locations over the cylinder surface under the constant Reynolds number of 6.1 × 104 based on the diameter of the cylinder. It is found that the length and the location both play important roles in the drag reduction. Two types of drag reduction can be seen: (1) when the relative length of the microfiber, k/D, is less than 1.8%, and the coating is applied before flow separates over the cylinder; and (2) k/D is over 3.3%, and the coating is applied after the flow separation location on the cylinder. The maximum drag reduction for the former type is 59% compared to that from the cylinder without the microfiber coating. For the latter type, the maximum drag reduction is 27%.

On the application of passive flow control for cavitation suppression in torque converter stator

2019 ◽  
Vol 29 (1) ◽  
pp. 204-222 ◽  
Author(s):  
Cheng Liu ◽  
Wei Wei ◽  
Qingdong Yan ◽  
Brian K. Weaver ◽  
Houston G. Wood
Keyword(s):  
Fluid Dynamics ◽  
Flow Control ◽  
Torque Converter ◽  
Control Technique ◽  
Content Type ◽  
Passive Flow Control ◽  
Cavitation Process ◽  
Passive Flow ◽  
Stator Blade ◽  
Torque Converters

Purpose The purpose of this paper is to study the transient cavitation process in torque converters with a particular focus on cavitation suppression with a passive flow control technique. Design/methodology/approach The transient fluid field in a torque converter was simulated by RANS-based computational fluid dynamics (CFD) in a full three-dimensional (3D) model. A homogeneous Rayleigh–Plesset cavitation model was used to simulate the transient cavitation process and the results were validated with test data. Various secondary flow passages (SFP) were applied to the stator blade. The cavitation behavior and hydrodynamic performance were simulated and compared to investigate the effect of SFP geometries on cavitation suppression. Findings Presented results show that cavitation in the torque converter is highly unstable at stall operating condition because of the combination of a high incidence angle and high flow velocity. The addition of an SFP to the stator blade produces a disruption of the re-entrant jet and reduces the overall degree of cavitation, consequently inhibiting the unstable cavitation and reducing performance degradation. Originality/value This paper provides unique insights into the complicated transient cavitation flow patterns found in torque converters and introduces effective passive flow control techniques useful to researchers and engineers in the areas of fluid dynamics and turbomachinery.

Bluff Body Drag Reduction Using Passive Flow Control of Jet Boat Tail

2015 ◽  
Vol 8 (2) ◽  
pp. 713-721 ◽  
Author(s):  
Trevor Hirst ◽  
Chuanpeng Li ◽  
Yunchao Yang ◽  
Eric Brands ◽  
Gecheng Zha
Keyword(s):  
Drag Reduction ◽  
Flow Control ◽  
Bluff Body ◽  
Passive Flow Control ◽  
Passive Flow ◽  
Body Drag

DETERMINATION OF DRAG AND LIFT RELATED COEFFICIENTS OF AN AUV USING COMPUTATIONAL AND EXPERIMENTAL FLUID DYNAMICS METHODS

2021 ◽  
Vol 162 (A2) ◽  
Author(s):  
E Javanmard ◽  
Sh Mansoorzadeh ◽  
A Pishevar ◽  
J A Mehr
Keyword(s):  
Fluid Dynamics ◽  
Autonomous Underwater Vehicle ◽  
Experimental Tests ◽  
Hydrodynamic Coefficients ◽  
Experimental Fluid Dynamics ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift ◽  
Control Surfaces ◽  
Experimental Fluid

Determination of hydrodynamic coefficients is a vital part of predicting the dynamic behavior of an Autonomous Underwater Vehicle (AUV). The aim of the present study was to determine the drag and lift related hydrodynamic coefficients of a research AUV, using Computational and Experimental Fluid Dynamics methods. Experimental tests were carried out at AUV speed of 1.5 m s-1 for two general cases: I. AUV without control surfaces (Hull) at various angles of attack in order to calculate Hull related hydrodynamic coefficients and II. AUV with control surfaces at zero angle of attack but in different stern angles to calculate hydrodynamic coefficients related to control surfaces. All the experiments carried out in a towing tank were also simulated by a commercial computational fluid dynamics (CFD) code. The hydrodynamic coefficients obtained from the numerical simulations were in close agreement with those obtained from the experiments.

Computational design and experimental testing of a flexible bi-stable airfoil for passive flow control

2021 ◽  
Author(s):  
Anurag Bhattacharyya ◽  
Mark Bashkawi ◽  
Se Yeon Kim ◽  
Wanzheng Zheng ◽  
Theresa Saxton-Fox ◽  
...  
Keyword(s):  
Flow Control ◽  
Experimental Testing ◽  
Computational Design ◽  
Passive Flow Control ◽  
Passive Flow
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