Flow control for a simplified truck using an array of streamwise synthetic jets

2018 ◽  
Author(s):  
Guglielmo Minelli ◽  
T. Liu ◽  
J. Zhang ◽  
Valery G. Chernoray ◽  
Branislav Basara ◽  
...  
Keyword(s):  
Flow Control ◽  
Synthetic Jets

Active flow control, for fixed wings, using synthetic jets

2022 ◽  
Author(s):  
Marcel Ilie ◽  
Jackson Asiatico ◽  
Matthew Chan
Keyword(s):  
Flow Control ◽  
Active Flow Control ◽  
Synthetic Jets ◽  
Active Flow

Flow Control Using Active Dimples

2004 ◽  
Author(s):  
Natalie Udovidchik ◽  
Sebastien Lambert
Keyword(s):  
Flow Control ◽  
Aerodynamic Drag ◽  
Spherical Shape ◽  
Reynolds Numbers ◽  
Synthetic Jets ◽  
Actuation Frequency ◽  
Flux Change ◽  
Novel Concept ◽  
Smart Surface

In this study, a novel concept of using active dimples for flow control is introduced. It is widely known that dimples on a golf ball dramatically reduce its aerodynamic drag. They are much more effective than surface roughness since the hollow spherical shape produces cavity flow, thus the drag coefficient remains relatively constant at higher Reynolds numbers. It has also been shown by previous studies that by use of circular-arc grooves or dimples, the separation point on a cylinder could be regulated and drag reduced due to the re-circulation occurring in the dimpled surface. Another approach to flow separation that uses the concept of momentum-flux change by near-wall manipulation is an active one, such as synthetic jets or acoustical excitation. The long-term goal of this study is to merge these two approaches and create a continuous smart surface that would have active depressions, which would then be actuated at desired frequencies and conform to a desired shape for optimal results. Current investigation had only touched the tip of the iceberg of this new and unexplored field. In order to begin to comprehend the complexity of the fluid mechanics of the active dimples, a dual focus had been outlined in this study. The first focused on the investigation of a single active dimple on a flat plate, while the latter investigated the effect of a row consisting of such devices on a circular cylinder. The main factors of interest are optimal actuation frequency and dimple positioning relative to the freestream.

Effective Range of Micro and Synthetic Jets for Flow Control

2005 ◽  
Author(s):  
Mehti Koklu ◽  
Nurhak Erbas ◽  
Oktay Baysal
Keyword(s):  
Flow Control ◽  
Moving Boundary ◽  
Rarefied Gas ◽  
Oscillation Amplitude ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Navier Stokes ◽  
Rarefied Gas Flows ◽  
Design Variables ◽  
Primary Focus

Effectiveness of two-dimensional synthetic jet is studied using numerical simulations. A Navier-Stokes (NS) solver for moving and deforming meshes has been modified to investigate numerically the diaphragm-driven flow in and out of two synthetic jet cavity geometries. Compressible flow simulations are required for rarefied gas flows to accurately predict the micro flow field. The solver is modified to accommodate slip wall boundary condition proposed in literature for micro scale flow problems. The piezoelectric-driven diaphragm of the cavity is modeled in a realistic manner as a moving boundary to accurately compute the flow inside the jet cavity. The primary focus of the proposed paper will be on the analysis of the design space determined by the geometric and flow-type design variables that identify the effectiveness of the synthetic jet by means of the orifice jet velocity and local jet momentum rate. The design variables are the membrane oscillation frequency (f), membrane oscillation amplitude (A), orifice width (d), and membrane width (W). The present computations for jet discharging into quiescent medium reveal that these variables have determining effects on the flow control parameters, which are the jet exit velocity, local momentum rate, as well as vortex shedding from the orifice.

Flow control on a 2D back-facing ramp by Synthetic Jets

2020 ◽  
Author(s):  
Giuseppe Ceglia ◽  
Marco Invigorito ◽  
Matteo Chiatto ◽  
Carlo Salvatore Greco ◽  
Gennaro Cardone ◽  
...  
Keyword(s):  
Flow Control ◽  
Synthetic Jets

Active Separation Control of Flow Over a Wall-Mounted Hump Using Zero-Efflux Synthetic Jet

2008 ◽  
Author(s):  
Subhadeep Gan ◽  
Urmila Ghia ◽  
Karman Ghia
Keyword(s):  
Flow Control ◽  
Turbulence Modeling ◽  
Separated Flow ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Experimental Results ◽  
Separation Control ◽  
Mean Flow ◽  
Modeling Approaches ◽  
Baseline Case

Most practical flows in engineering applications are turbulent, and exhibit separation which is generally undesirable because of its adverse effects on performance and efficiency. Therefore, control of turbulent separated flows has been a topic of significant interest as it can reduce separation losses. Often, flow control work employs passive techniques to manipulate the flow. These approaches do not require any additional energy source to achieve the control, but are accompanied by additional viscous losses. However, it is more desirable to employ active techniques as these can be turned on and off, depending on the flow control requirement. Use of synthetic jets has gained popularity in recent times for active flow control because of their ability to transfer linear momentum to the flow system without net-mass injection across the boundary in the vicinity of separation. The present work is Case 3 of the 2004 CFD Validation on Synthetic Jets and Turbulent Separation Control Workshop, http://cfdval2004.larc.nasa.gov/case3.html, conducted by NASA for the flow over a wall-mounted hump. This flow is characterized by a simple geometry, but, nevertheless, is rich in many complex flow phenomena such as shear layer instability, separation, reattachment, and vortex interactions. The baseline case and control case with steady suction has been successfully simulated by Gan et al., (2007 and 2008). The present work is focused on implementing a synthetic jet to achieve flow control. The jet was simulated by implementing an analytical sinusoidal velocity boundary condition at the surface of the jet exit. The jet-exit velocity has a parabolic profile across the control slot, and a sinusoidal temporal variation. The flow is simulated at a Reynolds number of 371,600, based on the hump chord length, C, and a Mach number of 0.04. The synthetic control jet exits through a slot located at approximately 0.65 C. Solutions are obtained using the three-dimensional RANS SST turbulence model, and the DES and LES turbulence modeling approaches. Multiple turbulence modeling approaches help to ascertain what techniques are most appropriate for capturing the physics of this complex separated flow. The location of the reattachment behind the hump is compared with experimental results. The successful control of this turbulent separated flow leads to a reduction in the reattachment length, compared with the baseline case. Velocity contours at several streamwise locations are presented and compared to experimental results. Mean flow parameters such as pressure coefficients and skin-friction coefficient are presented. The paper includes detailed comparisons of turbulent parameters such as the Turbulent Kinetic Energy (TKE) and Reynolds stress profiles, with experimental results. Instantaneous vorticity contours are presented from the simulations. Discussion are presented of the effects of synthetic jet control on flow separation and reattachment and the resulting enhancement of performance and efficiency.

Accuracy Investigation of Active Flow Control Using Synthetic Jets

2015 ◽  
Vol 741 ◽  
pp. 475-480
Author(s):  
Na Gao ◽  
Chen Pu ◽  
Bao Chen
Keyword(s):  
Flow Control ◽  
Velocity Distribution ◽  
Active Flow Control ◽  
Flow Fields ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Experimental Results ◽  
Center Line ◽  
Mean Velocity ◽  
The Mean

2nd order implicit format is implemented in the Navier-Stokes code to deal with instantaneous item unsteady flows. Three simulations are made to testify the method on flow control. First, the external flow fields of synthetic jets are simulated, the mean velocity on the center line, the jet width and velocity distribution are compared well with experimental results. Secondly, the flow fields of synthetic jet in a crossflow are simulated, orifice slot, the mean velocity on the center line and velocity distribution are compared well with experimental results. Finally, the flow control experiments on separation of airfoil are simulated, control methods include steady suction and synthetic jets. Both methods show their ability to favorably effect the flow separation, shortening the length of separation bubble and improving the pressure levels in separation areas in different degrees.

scholarly journals Flow control in axial fan inlet guide vanes by synthetic jets

2013 ◽  
Vol 45 ◽  
pp. 01021
Author(s):  
V. Cyrus ◽  
Z. Trávníček ◽  
P. Wurst ◽  
J. Kordík
Keyword(s):  
Flow Control ◽  
Synthetic Jets ◽  
Axial Fan ◽  
Guide Vanes ◽  
Inlet Guide Vanes
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