A Parametric Investigation of Jet and Vortex Actuator

2014 ◽  
Author(s):  
Sertac Cadirci ◽  
Hasan Gunes
Keyword(s):  
Numerical Study ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Wall Jet ◽  
Induced Flow ◽  
Zero Net Mass Flux ◽  
Active Flow ◽  
Jet Velocities ◽  
Plate Width

The Jet and Vortex Actuator (JaVA) is a zero-net-mass flux device for active flow control. In this numerical study, we present a parametric study of JaVA in quiescent water and obtain time-averaged flow and vorticity fields. We systematically investigate the effect of the governing parameters that affect on the JaVA - induced flow characteristics. Three jet Reynolds numbers are investigated in detail; ReJ = 68, 150 and 250 and for each jet-Reynolds number, four different wide-slot to plate width ratios are considered: gw = 0. 0166, 0.0338, 0.066 and 0.10. In all cases, the scaled amplitude is kept at Sa = 0.15 and 0.30 so that a total of 24 different simulations are investigated. JaVA - induced flow types are classified in five groups: wall-jet, vertical-oblique jet, chaotic jet, weak jet and vortex mode. Based on the governing parameters (Sa, ReJ and gw) all these flow types have been identified the jet-momentums are calculated from phase-averaged jet velocities obtained from numerical modeling results and compared to each other. It is found that generally the vortex mode transports the highest momentum flux followed by a chaotic jet.

Numerical Investigation of JaVA-Induced Flow in Quiescent Water

2013 ◽  
Author(s):  
Sertac Cadirci ◽  
Hasan Gunes ◽  
Ulrich Rist
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Flow Fields ◽  
Control Device ◽  
Flow Control Device ◽  
Induced Flow ◽  
Wide Gap ◽  
Zero Net Mass Flux ◽  
Quiescent Fluid

A Jet and Vortex Actuator (JaVA) is an oscillatory, zero-net-mass flux active flow control device which has been investigated numerically in quiescent water. JaVA consists of a vertically moving actuating plate and ejects jets or vortices into the quiescent fluid. Main JaVA-induced flow regimes include jets to different orientations and vortex mode. In this paper, we investigate the effect of the wide gap on the flow characteristics. Three cases consisting of two jets and one vortex mode are presented in detail where the jet-Reynolds number and the scaled amplitude are kept constant. Computational results have been reported to depict instantaneous fields and reveal temporal behavior of JaVA-induced flows in quiescent fluid. In addition, the phase-averaged flow fields have been obtained for suction and blowing phases. The velocity profiles extracted from phase-averaged flow fields across the wide gap supply further insight into the JaVA-induced flow regime and their effectiveness in flow control.

scholarly journals Modal Reduction of Synthetic Jet Actuator Based Separation Control With Spectral POD

2020 ◽  
Author(s):  
Xuan Shi ◽  
Pierre Sullivan
Keyword(s):  
Flow Behavior ◽  
Spatial Scales ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Separation Control ◽  
Synthetic Jet Actuator ◽  
Zero Net Mass Flux ◽  
Active Flow

Abstract A synthetic jet actuator (SJA) is a zero-net-mass-flux device that imparts fluid momentum and is useful for active flow control (AFC). In many applications, airfoil performance is often limited or degraded by flow separation which is usually associated with loss of lift, increased drag, and kinetic energy losses. Therefore, it is of interest to investigate methods of separation region suppression with the forcing control of SJA. This paper studies the flow behavior of cross flow over an airfoil and how the addition of SJA influences flow characteristics. Using the Spectral Proper Orthogonal Decomposition and LES simulation, flow instabilities in the wake region are analyzed in their different temporal and spatial scales. The objective of this study is to explore the viability of SPOD for separation control and correlating the decomposed flow modes to the aerodynamic performance of airfoil.

Conceptual design and numerical studies of active flow control aerofoil based on shape-memory alloy and macro fibre composites

2021 ◽  
Vol 125 (1287) ◽  
pp. 830-846
Author(s):  
W. Zhang ◽  
X.T. Nie ◽  
X.Y. Gao ◽  
W.H. Chen
Keyword(s):  
Shape Memory Alloy ◽  
Flow Control ◽  
Shape Memory ◽  
Vibration Frequency ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Hybrid Design ◽  
Numerical Studies ◽  
Fibre Composites ◽  
Active Flow

ABSTRACTActive flow control for aerofoils has been proven to be an effective way to improve the aerodynamic performance of aircraft. A conceptual hybrid design with surfaces embedded with Shape-Memory Alloy (SMA) and trailing Macro Fibre Composites (MFC) is proposed to implement active flow control for aerofoils. A Computational Fluid Dynamics (CFD) model has been built to explore the feasibility and potential performance of the proposed conceptual hybrid design. Accordingly, numerical analysis is carried out to investigate the unsteady flow characteristics by dynamic morphing rather than using classical static simulations and complicated coupling. The results show that camber growth by SMA action could cause an evident rise of Cl and Cd in the take-off/landing phases when the Angle-of-Attack (AoA) is less than 10°. The transient tail vibration behaviour in the cruise period when using MFC actuators is studied over wide ranges of frequency, AoA and vibration amplitude. The buffet frequency is locked in by the vibration frequency, and a decrease of 1.66–2.32% in Cd can be achieved by using a proper vibration frequency and amplitude.

NUMERICAL STUDY OF CONTROL OF FLOW SEPARATION OVER A RAMP WITH NANOSECOND PLASMA ACTUATOR

2016 ◽  
Vol 42 ◽  
pp. 1660151
Author(s):  
J. G. ZHENG ◽  
B. C. KHOO ◽  
Y. D. CUI ◽  
Z. J. ZHAO ◽  
J. LI
Keyword(s):  
Flow Separation ◽  
Control Mechanism ◽  
Numerical Study ◽  
Active Flow Control ◽  
Ambient Air ◽  
High Voltage Pulse ◽  
External Flow ◽  
Characterization Study ◽  
Active Flow ◽  
Residual Heat

The nanosecond plasma discharge actuator driven by high voltage pulse with typical rise and decay time of several to tens of nanoseconds is emerging as a promising active flow control means in recent years and is being studied intensively. The characterization study reveals that the discharge induced shock wave propagates through ambient air and introduces highly transient perturbation to the flow. On the other hand, the residual heat remaining in the discharge volume may trigger the instability of external flow. In this study, this type of actuator is used to suppress flow separation over a ramp model. Numerical simulation is carried out to investigate the interaction of the discharge induced disturbance with the external flow. It is found that the flow separation region over the ramp can be reduced significantly. Our work may provide some insights into the understanding of the control mechanism of nanosecond pulse actuator.

scholarly journals Numerical study on the steady suction active flow control of hydrofoil in the profile of the blended-wing-body underwater glider

2021 ◽  
Vol 39 (4) ◽  
pp. 801-809
Author(s):  
Xiaoxu Du ◽  
Lianying Zhang
Keyword(s):  
Flow Control ◽  
Numerical Study ◽  
Active Flow Control ◽  
Lift Coefficient ◽  
Leading Edge ◽  
Hydrodynamic Performance ◽  
Flow State ◽  
Underwater Glider ◽  
Blended Wing Body ◽  
Active Flow

The hydrodynamic performance of the blended-wing-body underwater glider can be improved by opening a hole on the surface and applying the steady suction active flow control. In order to explore the influence law and mechanism of the steady suction active flow control on the lift and drag performance of the hydrofoil, which is the profile of the blended-wing-body underwater glider, based on the computational fluid dynamics (CFD) method and SST k-ω turbulence model, the steady suction active flow control of hydrofoil under different conditions is studied, which include three suction factors: suction angle, suction position and suction ratio, as well as three different flow states: no stall, critical stall and over stall. Then the influence mechanism in over stall flow state is further analyzed. The results show that the flow separation state of NACA0015 hydrofoil can be effectively restrained and the flow field distribution around it can be improved by a reasonable steady suction, so as to the lift-drag performance of NACA0015 hydrofoil is improved. The effect of increasing lift and reducing drag of steady suction is best at 90° suction angle and symmetrical about 90° suction angle, and it is better when the steady suction position is closer to the leading edge of the hydrofoil. In addition, with the increase of the suction ratio, the influence of steady suction on the lift coefficient and drag coefficient of hydrofoil is greater.

Highly responsive multi-flow pattern generation by multi-electrode plasma actuator using a single power supply

2021 ◽  
Author(s):  
Kosuke Sugimoto ◽  
Satoshi Ogata
Keyword(s):  
Flow Control ◽  
Flow Pattern ◽  
Power Supply ◽  
Active Flow Control ◽  
Flow Patterns ◽  
Plasma Actuator ◽  
Pattern Generation ◽  
Switching Frequency ◽  
Wall Jet ◽  
Active Flow

Abstract A dielectric-barrier-discharge plasma actuator (DBD-PA) is an active flow-control device that uses ionic wind generated by electrohydrodynamic (EHD) forces. A DBD-PA controls fluid motion and offers quick response without the need for moving parts. Previous studies have proposed methods for generating various flow patterns with a DBD-PA for fluid control. This paper presents a method for generating multiple flow patterns using a multi-electrode DBD-PA that is driven by a single-channel high-voltage power supply with a relay circuit. In contrast, conventional methods of realizing multiple flow patterns involve the use of a multi-channel power supply. Hence, they have the disadvantage of requiring a complicated power supply system. The proposed method succeeded in realizing several induced-flow modes involving the generation of a directionally controllable wall jet, various sizes of vortices, and an upward jet by altering the switching frequency and switching ratio. In addition, our experimental results indicate that the proposed method can control the flow pattern with a significantly short response time. The direction of the wall jet can be switched within tens to hundreds of milliseconds. Therefore, the proposed method combines simplicity and versatility and is expected to facilitate the realization of multifunctional active flow control in various flow fields, such as flow turbulent boundary layer control, thermal diffusion control, gas mixing, and flame-stability enhancement.

Use of Micro Synthetic Jet Actuators for Boundary Layer Flow Control

2009 ◽  
Vol 74 ◽  
pp. 157-160
Author(s):  
Jing Chuen Lin ◽  
An Shik Yang ◽  
Li Yu Tseng
Keyword(s):  
Boundary Layer ◽  
Flow Control ◽  
Turbulent Flows ◽  
Boundary Layer Flow ◽  
Moving Boundary ◽  
Active Flow Control ◽  
Flow Characteristics ◽  
Synthetic Jet ◽  
Layer Flow ◽  
Active Flow

The main purpose of active flow control research is to develop a cost-effective technology that has the potential for inventive advances in aerodynamic performance and maneuvering compared to conventional approaches. It can be essential to thoroughly understand the flow characteristics of the formation and interaction of a synthetic jet with external crossflow before formulating a practicable active flow control strategy. In this study, the theoretical model used the transient three-dimensional conservation equations of mass and momentum for compressible, isothermal, turbulent flows. The motion of a movable membrane plate was also treated as the moving boundary by prescribing the displacement on the plate surface. The predictions by the computational fluid dynamics (CFD) code ACE+® were compared with measured transient phase-averaged velocities of Rumsey et al. for software validation. The CFD software ACE+® was utilized for numerical calculations to probe the time evolution of the development process of the synthetic jet and its interaction within a turbulent boundary layer flow for a complete actuation cycle.

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