Utilizing the L-PSJA for controlling cylindrical wake flow

2016 ◽  
Vol 26 (5) ◽  
pp. 1593-1616 ◽  
Author(s):  
Martin Skote ◽  
Imran Halimi Ibrahim
Keyword(s):  
Flow Control ◽  
Acoustic Noise ◽  
Control Device ◽  
Synthetic Jet ◽  
Wake Flow ◽  
Content Type ◽  
Synthetic Jet Actuator ◽  
Drag Forces ◽  
Flow Control Devices ◽  
Wake Turbulence

Purpose – The cylindrical wake flow is an important part of many engineering applications, including wake turbulence, acoustic noise, and lift/drag forces on bodies. The suppression of von Kármán vortex street (VKS) is an important goal for flow control devices. The paper aims to discuss these issues. Design/methodology/approach – The linear plasma synthetic jet actuator (L-PSJA) is utilized as a flow control device to suppress the VKS formation. Different configurations of the device is studied numerically. Findings – Of the 12 configurations that were investigated, five configurations were able to suppress the formation of the VKS. Originality/value – For the first time, the L-PSJA has been shown (through numerical simulations) to be able to suppress VKS.

Control of Separated Flow Past Backward-Facing Step in Microchannel

2004 ◽  
Author(s):  
O. Baysal ◽  
N. Erbas ◽  
M. Koklu
Keyword(s):  
Flow Control ◽  
Oscillation Amplitude ◽  
Separated Flow ◽  
Control Device ◽  
Synthetic Jet ◽  
Navier Stokes ◽  
Backward Facing Step ◽  
Synthetic Jet Actuator ◽  
Flow Past ◽  
Optimization Methodology

A key concern for micro device design is its power consumption. When such a device involves microflows, actively controlling the flow losses often reduces the power requirements. In the present study, a micro synthetic jet is proposed as a flow control device. The method used is an automated design optimization methodology coupled with computational fluid dynamics. Microflows in the Knudsen range of 10−3 to 10−1 are modeled using a Navier-Stokes solver but with slip velocity and temperature jump boundary conditions derived for micro-sized geometries. First, an uncontrolled flow past a backward facing step in a channel is computed. Then, a synthetic jet actuator is placed downstream of the step where the separation occurs. A large number of test cases have been analyzed. It has been observed that the reattachment point of the separated flow and the flow dissipation are quite sensitive to the location and the geometry of the synthetic jet as well as the parameters of the oscillating membrane. The best flow control, defined as the largest decrease in dissipation, is obtained when the actuator cavity width and the membrane oscillation amplitude are increased simultaneously.

scholarly journals Control of flow separation over a circular cylinder using synthetic jet

2021 ◽  
Vol 2119 (1) ◽  
pp. 012025
Author(s):  
A. S. Lebedev ◽  
M. I. Sorokin ◽  
D. M. Markovich
Keyword(s):  
Circular Cylinder ◽  
Flow Control ◽  
Flow Separation ◽  
Gas Turbines ◽  
Acoustic Noise ◽  
Reverse Flow ◽  
Flow Region ◽  
Synthetic Jet ◽  
Separation Flow ◽  
Longitudinal Length

Abstract The development of methods of active separation flow control is of great applied importance for many technical and engineering applications. Understanding the conditions for the flow separation from the surface of a bluff body is essential for the design of aircrafts, cars, hydro and gas turbines, bridges and buildings. Drag, acoustic noise, vibrations and active flow mixing depend drastically on the parameters of the vortex separation process. We investigated the possibility of reducing the longitudinal length of a reverse-flow region using the method of «synthetic jet» active separation flow control. The experiment was carried out on a compact straight-through wind channel with a 1-m long test section of a cross-section of 125x125 mm. The jet was placed at the rear stagnation point of a circular cylinder. The Reynolds number, based on the cylinder diameter and the free-stream velocity, was 5000 and the von Kármán street shedding frequency without the synthetic jet was equal to 64.8 Hz. For the first time, for such a set of parameters, we applied high speed PIV to demonstrate that the injection of the synthetic jet into the cylinder wake region leads to a significant reduction in the longitudinal length of the reverse-flow region.

Flow Control to the surface on Airfoil with Plasma Synthetic Jet Actuator

2003 ◽  
Vol 2003.7 (0) ◽  
pp. 255-256
Author(s):  
Naoki NAKATANI ◽  
Kakuji OGAWARA ◽  
Souichi SAEKI
Keyword(s):  
Flow Control ◽  
Synthetic Jet ◽  
Synthetic Jet Actuator

A Study on Synthetic Jet Actuator Diaphragm

2015 ◽  
Vol 14 (02) ◽  
pp. 91-105
Author(s):  
Siddhartha Sankar Deka ◽  
Rituraj Gautam ◽  
Anoop Singh ◽  
Gautam Kumar ◽  
Promod Kumar Patowari
Keyword(s):  
Structural Characteristics ◽  
Active Flow Control ◽  
Control Device ◽  
Synthetic Jet ◽  
Circular Disc ◽  
Response Analysis ◽  
Synthetic Jet Actuator ◽  
Piezoelectric Patch ◽  
Annular Disc ◽  
Patch Configuration

A synthetic jet actuator (SJA) is one of the most widely used active flow control device which uses a vibrating diaphragm enclosed within a cavity to generate the fluid jet. The effectiveness of the actuator greatly depends upon the design of cavity and orifice and the diaphragm properties. A lot of emphasis is being laid on the cavity and orifice design, but very few literatures can be found dealing with the diaphragm of the SJA. Thus, in this paper a study of the SJA diaphragm actuated by piezoelectric ceramics of different geometries is being presented. Three different diaphragm materials — brass, poly-silicon and aluminum and five different geometries of the piezoelectric actuators — annular disc shaped actuator patch, annular shaped actuator, rectangular shaped actuator patch and circular disc shaped actuator patch and two cantilever arrangements are being considered. A static analysis is carried out and a comparison of the parameters which affect the performance of the SJA is done. Frequency response analysis is also carried out to obtain a better understanding of the diaphragm's structural characteristics. The results thus obtained show that an annular disc piezoelectric patch configuration shows the best behavior as compared to the other actuator configurations and is closely followed by circular disc piezoelectric patch configuration.

Experimental Characterization of a Micro-Blower for Flow Control

2019 ◽  
Author(s):  
Maria Wu ◽  
Pierre Sullivan
Keyword(s):  
Flow Control ◽  
Turbulent Jets ◽  
Synthetic Jet ◽  
Experimental Characterization ◽  
Continuous Mode ◽  
Mean Velocity ◽  
Burst Mode ◽  
Synthetic Jet Actuator ◽  
Image Velocimetry

Abstract A compact, lightweight, low-power piezoelectric micro-blower was characterized using particle image velocimetry to determine its flow control potential. The micro-blower has been operated in continuous mode as well as in burst mode using two different actuation frequencies. The maximum mean velocity measured with the micro-blower operating in continuous mode was approximately Ūmax = 13 m/s which occurred at the centerline at an approximate stream-wise location of x/d = 4. The velocity profiles in the developed region resemble those of turbulent jets. The momentum-flux from the micro-blower in continuous mode was significantly greater than a typical synthetic jet actuator which was successfully used for flow control, indicating that the micro-blower can impart the necessary momentum to be effective for flow control. With burst mode, the results show that the micro-blower could impart an even greater momentum.

Phase Locked Analysis of a Simplified Car Geometry Wake Flow Control Using Synthetic Jet

2006 ◽  
Author(s):  
Ce´dric Leclerc ◽  
Euge´nie Levallois ◽  
Quentin Gallas ◽  
Patrick Gillie´ron ◽  
Azeddine Kourta
Keyword(s):  
Boundary Layer ◽  
Turbulent Boundary Layer ◽  
Drag Reduction ◽  
Vortex Shedding ◽  
Aerodynamic Drag ◽  
Streamwise Velocity ◽  
Local Effect ◽  
Synthetic Jet ◽  
Wake Flow ◽  
Synthetic Jet Actuator

This paper presents a numerical unsteady analysis of a SJA impact on a car wake flow. First, for the optimal reduced frequency F+, the influence of the Cμ on the mean aerodynamic drag reduction 〈Cd〉 is observed. A spectral analysis of the vortex shedding coming from the upper and the lower part of the car and of the drag coefficient is then presented for different Cμ values. Preliminary results suggest that maximum drag reduction is obtained when most energy in the wake comes from the actuator forcing frequency rather than the natural vortex shedding frequencies of the two contributions. This work is completed by a phase locked analysis of the synthetic jet actuator local effect on the turbulent boundary layer just before the flow separation. For the fixed optimal F+, different Cμ values are compared. The streamwise velocity profiles seem to show that maximal efficiency of the control is obtained when the synthetic jet injected momentum is introduced in the logarithmic sub-layer part of the turbulent boundary layer.

Sign in / Sign up

Export Citation Format

Share Document