Drag reduction due to recirculating bubble control using plasma actuator on a squareback model

Flow control on a squareback object which resembles many engineering related objects is believed to be highly beneficial. One of the flow characteristics behind the object, recirculating bubble, is known to play significant role in pressure distribution. Meanwhile, plasma actuator implementation on such object is still underdeveloped in application basis. This paper focuses on acquiring a deeper understanding of plasma actuator effect on flow phenomenon behind a squareback object, especially on its application to recirculating bubble control in order to reduce drag. The experiment was divided into drag measurement experiment and visualization experiment. The drag measurement result shows that plasma actuator succeeded on reducing drag up to 15.36% in the lowest Reynolds number. Meanwhile, the visualization experiment shows that plasma actuator has shifted the recirculating bubble position to be closer to the object’s wall.

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Effect of Compressibility on Gaseous Flows in a Micro-Tube

Heat Transfer: Volume 1 ◽

10.1115/ht2003-47166 ◽

2003 ◽

Cited By ~ 2

Author(s):

Yutaka Asako ◽

Kenji Nakayama

Keyword(s):

Reynolds Number ◽

Mach Number ◽

Pressure Distribution ◽

Flow Characteristics ◽

Fused Silica ◽

Two Dimensional ◽

Arbitrary Lagrangian Eulerian ◽

Gaseous Flow ◽

Gaseous Flows ◽

Energy Equations

The product of friction factor and Reynolds number (f·Re) of gaseous flow in the quasi-fully developed region of a micro-tube was obtained experimentally and numerically. The tube cutting method was adopted to obtain the pressure distribution along the tube. The fused silica tubes whose nominal diameters were 100 and 150 μm, were used. Two-dimensional compressible momentum and energy equations were solved to obtain the flow characteristics in micro-tubes. The numerical methodology is based on the Arbitrary-Lagrangian-Eulerian (ALE) method. The both results agree well and it was found that (f·Re) is a function of Mach number.

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Experimental Study on Pressure Distribution and Flow Coefficient of Globe Valve

Processes ◽

10.3390/pr8070875 ◽

2020 ◽

Vol 8 (7) ◽

pp. 875 ◽

Cited By ~ 3

Author(s):

Quang Khai Nguyen ◽

Kwang Hyo Jung ◽

Gang Nam Lee ◽

Sung Bu Suh ◽

Peter To

Keyword(s):

Reynolds Number ◽

Pressure Distribution ◽

Full Range ◽

Flow Characteristics ◽

National Standards ◽

Flow Coefficient ◽

Test Loop ◽

Close Range ◽

Valve Opening ◽

Globe Valve

In this study, the pressure distribution and flow coefficient of a globe valve are investigated with a series of experiments conducted in a flow test loop. The experiments are performed on a three-inch model test valve from an eight-inch ANSI (American National Standards Institute) B16.11—Class 2500# prototype globe valve with various pump speeds and full range of valve openings. Both inherent and installed flow characteristics are measured, and the results show that the flow coefficient depends not only on the valve geometry and valve opening but also on the Reynolds number. When the Reynolds number exceeds a certain value, the flow coefficients are stable. In addition, the pressures at different positions in the upstream and the downstream of the valve are measured and compared with recommendation per ANSI/ISA-75.01 standard. The results show that, in single-phase flow, the discrepancies in pressure between different measurement locations within close range of 10 nominal diameter from the valve are inconsiderable.

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Lift Coefficients and Pressure Distribution Acting on Two Tandem Cylinders of Different Diameters

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.886.417 ◽

2014 ◽

Vol 886 ◽

pp. 417-421

Author(s):

Yong Tao Wang ◽

Zhong Min Yan ◽

Hui Min Wang

Keyword(s):

Reynolds Number ◽

Pressure Distribution ◽

Flow Characteristics ◽

Diameter Ratio ◽

Tandem Arrangement ◽

Tandem Cylinders ◽

Gap Ratio ◽

Different Diameters ◽

Upstream Control ◽

Control Cylinder

Flow characteristics of two different diameters cylinders in a tandem arrangement were investigated numerically in a uniform flow. The diameter of the downstream main cylinder was kept constant, and the diameter ratio between the upstream control cylinder and the downstream one was varied from 0.1 to 1.0. The studied Reynolds number based on the diameter of the downstream main cylinder were 100 and 150. The gap between the control cylinder and the main cylinder ranged from 0.1 to 4.0 times the diameter of the main cylinder. It is concluded that the gap ratio and the diameter ratio between the two cylinders have important effects on the lift coefﬁcients and pressure distribution.

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Turbulent Flow of Dilute Aqueous Polymer Solutions

Journal of Basic Engineering ◽

10.1115/1.3609710 ◽

1967 ◽

Vol 89 (4) ◽

pp. 814-822 ◽

Cited By ~ 37

Author(s):

Y. Goren ◽

J. F. Norbury

Keyword(s):

Reynolds Number ◽

Turbulent Flow ◽

Drag Reduction ◽

Polymer Concentration ◽

Flow Characteristics ◽

Detailed Examination ◽

Turbulent Shear ◽

Solid Boundary ◽

Polymer Additives ◽

Turbulent Shear Flow

This paper summarizes some of the research into the effect of polymer additives on turbulent shear flow, which was conducted at the University of Liverpool between October, 1964, and October, 1966. The paper contains a brief description of the research together with a summary of the principal results and conclusions. The present work was devoted to a detailed examination of the mechanism of a particular flow by gathering information on friction drag, velocity distribution, concentration distribution, and correlation with Reynolds number and polymer concentration level. The particular flow chosen was the fully developed turbulent flow in a 2-in-dia pipe of Polyox WSR-301 solutions. A maximum drag reduction of 71 percent was obtained at a Reynolds number of 1.5 × 105 for solutions having polymer concentration of 10 weight parts per million. The drag reduction effect occurred only above some “critical” Reynolds number which was independent of concentration. The polymer additives were found to influence the flow in the neighborhood of a solid boundary. In this zone of the flow, the eddy viscosity was found to be much lower than that of water. In the absence of a boundary, as in free jet flow, the polymer additives had no effect on the flow characteristics. The experiments showed for the first time that the polymer molecules were uniformly distributed across the pipe diameter under all turbulent flow conditions investigated. A method of determining polymer concentration was devised for this purpose.

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Experimental Study of Flow Control Over a Standard Road Vehicle Using Plasma Actuator

Mechanics and Mechanical Engineering ◽

10.2478/mme-2018-0083 ◽

2020 ◽

Vol 22 (4) ◽

pp. 1047-1060

Author(s):

S. Shadmani ◽

S. M. Mousavi Nainiyan ◽

R. Ghasemiasl ◽

M. Mirzaei ◽

S. G. Pouryoussefi

Keyword(s):

Flow Control ◽

Pressure Distribution ◽

Drag Force ◽

Separated Flow ◽

Plasma Actuator ◽

Road Vehicle ◽

Slant Angle ◽

Total Drag ◽

Slant Surface ◽

Ahmed Body

AbstractAhmed Body is a standard and simplified shape of a road vehicle that's rear part has an important role in flow structure and it's drag force. In this paper flow control around the Ahmed body with the rear slant angle of 25° studied by using the plasma actuator system situated in middle of the rear slant surface. Experiments conducted in a wind tunnel in two free stream velocities of U = 10m/s and U = 20m/s using steady and unsteady excitations. Pressure distribution and total drag force were measured and smoke flow visualization carried out in this study. The results showed that at U = 10m/s using plasma actuator suppress the separated flow over the rear slant slightly and be effective on pressure distribution. Also, total drag force reduces in steady and unsteady excitations for 3.65% and 2.44%, respectively. At U = 20m/s, using plasma actuator had no serious effect on the pressure distribution and total drag force.

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Vortex Packets in Turbulent Boundary Layers with Application to High Reynolds Number Effects, Isolated and Patterned Roughness, Near Wall Modeling and Strategies for Drag Reduction

10.21236/ada390542 ◽

2001 ◽

Cited By ~ 1

Author(s):

R. J. Adrian ◽

S. Balachandar

Keyword(s):

Reynolds Number ◽

Drag Reduction ◽

Boundary Layers ◽

High Reynolds Number ◽

Turbulent Boundary Layers ◽

Reynolds Number Effects ◽

High Reynolds ◽

Near Wall

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High Reynolds Number Micro-Bubble and Polymer Drag Reduction Experiments

10.21236/ada476433 ◽

2008 ◽

Author(s):

Steven L. Ceccio ◽

David R. Dowling ◽

Marc Perlin ◽

Michael Solomon

Keyword(s):

Reynolds Number ◽

Drag Reduction ◽

High Reynolds Number ◽

Polymer Drag Reduction ◽

Micro Bubble ◽

High Reynolds

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Noise Reduction Effect of Superhydrophobic Surfaces with Streamwise Strip of Channel Flow

Applied Sciences ◽

10.3390/app11093869 ◽

2021 ◽

Vol 11 (9) ◽

pp. 3869

Author(s):

Chen Niu ◽

Yongwei Liu ◽

Dejiang Shang ◽

Chao Zhang

Keyword(s):

Reynolds Number ◽

Drag Reduction ◽

Noise Reduction ◽

Channel Flow ◽

Superhydrophobic Surface ◽

Sound Field ◽

Flow Noise ◽

Slip Boundary ◽

Eddy Simulation ◽

Reduction Effect

Superhydrophobic surface is a promising technology, but the effect of superhydrophobic surface on flow noise is still unclear. Therefore, we used alternating free-slip and no-slip boundary conditions to study the flow noise of superhydrophobic channel flows with streamwise strips. The numerical calculations of the flow and the sound field have been carried out by the methods of large eddy simulation (LES) and Lighthill analogy, respectively. Under a constant pressure gradient (CPG) condition, the average Reynolds number and the friction Reynolds number are approximately set to 4200 and 180, respectively. The influence on noise of different gas fractions (GF) and strip number in a spanwise period on channel flow have been studied. Our results show that the superhydrophobic surface has noise reduction effect in some cases. Under CPG conditions, the increase in GF increases the bulk velocity and weakens the noise reduction effect. Otherwise, the increase in strip number enhances the lateral energy exchange of the superhydrophobic surface, and results in more transverse vortices and attenuates the noise reduction effect. In our results, the best noise reduction effect is obtained as 10.7 dB under the scenario of the strip number is 4 and GF is 0.5. The best drag reduction effect is 32%, and the result is obtained under the scenario of GF is 0.8 and strip number is 1. In summary, the choice of GF and the number of strips is comprehensively considered to guarantee the performance of drag reduction and noise reduction in this work.

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Dynamic flight load measurements with MEMS pressure sensors

CEAS Aeronautical Journal ◽

10.1007/s13272-021-00529-3 ◽

2021 ◽

Author(s):

Christian Raab ◽

Kai Rohde-Brandenburger

Keyword(s):

Pressure Distribution ◽

Pressure Sensors ◽

Flow Characteristics ◽

Flight Test ◽

Measurement Technology ◽

Test Program ◽

Aerodynamic Pressure ◽

Pressure Distributions ◽

Time Histories ◽

Mems Pressure Sensors

AbstractThe determination of structural loads plays an important role in the certification process of new aircraft. Strain gauges are usually used to measure and monitor the structural loads encountered during the flight test program. However, a time-consuming wiring and calibration process is required to determine the forces and moments from the measured strains. Sensors based on MEMS provide an alternative way to determine loads from the measured aerodynamic pressure distribution around the structural component. Flight tests were performed with a research glider aircraft to investigate the flight loads determined with the strain based and the pressure based measurement technology. A wing glove equipped with 64 MEMS pressure sensors was developed for measuring the pressure distribution around a selected wing section. The wing shear force determined with both load determination methods were compared to each other. Several flight maneuvers with varying loads were performed during the flight test program. This paper concentrates on the evaluation of dynamic flight maneuvers including Stalls and Pull-Up Push-Over maneuvers. The effects of changes in the aerodynamic flow characteristics during the maneuver could be detected directly with the pressure sensors based on MEMS. Time histories of the measured pressure distributions and the wing shear forces are presented and discussed.

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