Interaction of a Finite-Span Synthetic-Jet and a Cross-Flow over a Sweptback Finite Wing

2012 ◽  
Author(s):  
Josheph Vasile ◽  
Michael Amitay
Keyword(s):  
Cross Flow ◽  
Synthetic Jet ◽  
Finite Span ◽  
Finite Wing

Secondary flow structures due to interaction between a finite-span synthetic jet and a 3-D cross flow

2011 ◽  
Vol 23 (9) ◽  
pp. 094104 ◽  
Author(s):  
Yossef Elimelech ◽  
Joseph Vasile ◽  
Michael Amitay
Keyword(s):  
Secondary Flow ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Flow Structures ◽  
Finite Span

Interaction of a Finite-span Synthetic-jet and Cross-flow over a Swept Wing

2010 ◽  
Author(s):  
Joseph Vasile ◽  
Yossef Elimelech ◽  
John Farnsworth ◽  
Michael Amitay ◽  
Keneth Jansen
Keyword(s):  
Cross Flow ◽  
Synthetic Jet ◽  
Swept Wing ◽  
Finite Span

Assessment of Cooling Enhancement of Synthetic Jet in Conjunction With Forced Convection

2007 ◽  
Author(s):  
Yogen Utturkar ◽  
Mehmet Arik ◽  
Mustafa Gursoy
Keyword(s):  
Forced Convection ◽  
Cross Flow ◽  
Electronics Cooling ◽  
Synthetic Jet ◽  
Synthetic Jets ◽  
Channel Height ◽  
Large Area ◽  
Complete Replacement ◽  
Cooling Enhancement ◽  
The Impact

Synthetic jets are meso or micro fluidic devices, which operate on the “zero-net-mass-flux” principle. They impart a positive net momentum flux to the external environment, and are able to produce the cooling effect of a fan sans its ducting, reliability issues, and oversized dimensions. As a result, recently their application as electronics cooling devices is gaining momentum. Traditionally, synthetic jets have been sought as a replacement to the fan in many electronic devices. However, in certain large applications, complete replacement of the fan is not feasible, because it is necessary to provide the basic level of cooling over a large area of a printed assembly board. Such applications often pose a question whether synthetic jet would be able to locally provide reasonable enhancement over the forced convection of the fan flow. In the present study, we present the cooling performance of synthetic jets complementing forced convection from a fan. Both experiments and CFD computations are performed to investigate the interaction of the jet flowfield with a cross flow from fan. The inlet velocity, jet disk amplitude, and channel height are varied in the computational simulations to evaluate the impact of these changes on the cooling properties. Overall, both studies show that a synthetic jet is able to pulse and disrupt the boundary layer caused from fan flow, and improve heat transfer up to 4× over forced convection.

Measurement of Downwash at a Mach Number of 1.45 Behind Two Wings of Finite Span

1951 ◽  
Vol 55 (481) ◽  
pp. 43-51
Author(s):  
W. F. Hilton
Keyword(s):  
Reynolds Number ◽  
Mach Number ◽  
Rear Surface ◽  
Similar Magnitude ◽  
Trailing Edge ◽  
Finite Span ◽  
Finite Wing

Measurements were made of the downwash effects behind two finite wings 3.1 percent, thick, having square and 20° raked tips respectively. The tests were conducted at a Mach number of 1.45 and a Reynolds number of 1.2 millions by traversing a yawmeter 1.62 chords behind the trailing edge of the finite wings.In general, a maximum downwash of the order of ½° per degree of wing incidence was observed in that portion of the tip Mach cone behind the wing, and a maximum upwash of similar magnitude was observed in that part of the tip Mach cone situated outboard of the wing.Thus it is apparent that these effects are large enough to affect the lift on any surface situated in the tip Mach cone behind a finite wing. In particular, placing the rear surface in the downwash region behind a finite wing, will tend to reduce the overall lift while placing it in the upwash region will tend to magnifiy the variations of lift initiated by the finite wing.

Effects of vortex-induced velocity on the development of a synthetic jet issuing into a turbulent boundary layer

2019 ◽  
Vol 870 ◽  
pp. 651-679 ◽  
Author(s):  
Tim Berk ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Velocity Field ◽  
Momentum Transfer ◽  
Momentum Flux ◽  
Cross Flow ◽  
Measured Data ◽  
Velocity Fields ◽  
Synthetic Jet ◽  
Vortical Structures ◽  
The Cross ◽  
Induced Velocity

A synthetic jet issuing into a cross-flow influences the local velocity of the cross-flow. At the jet exit the jet is oriented in the wall-normal direction while the cross-flow is oriented in the streamwise direction, leading to a momentum transfer between the jet and the cross-flow. Streamwise momentum transferred from the cross-flow to the jet accelerates the pulses created by the jet. This momentum transfer continuous up to some point downstream where these pulses have the same velocity as the surrounding flow and are no longer blocking the cross-flow. The momentum transfer from the cross-flow to the jet leads to a momentum deficit in the cross-flow far downstream of the viscous near field of the jet. In the literature this momentum-flux deficit is often attributed to viscous blockage or to up-wash of low-momentum fluid. The present paper proposes and quantifies a third source of momentum deficit: a velocity induced opposite to the cross-flow by the vortical structures created by the synthetic jet. These vortical structures are reconstructed from measured data and their induced velocity is calculated using the Biot–Savart law. The three-dimensional three-component induced velocity fields show great similarity to the measured velocity fields, suggesting that this induced velocity is the main contributor to the velocity field around the synthetic jet and viscous effects have only a small influence. The momentum-flux deficit induced by the vortical structures is compared to the measured momentum-flux deficit, showing that the main part of this deficit is caused by the induced velocity. Variations with Strouhal number (frequency of the jet) and velocity ratio (velocity of the jet) are observed and discussed. An inviscid-flow model is developed, which represents the downstream evolution of the jet in cross-flow. Using the measured data as an input, this model is able to predict the deformation, (wall-normal) evolution and qualitative velocity field of the jet. The present study presents evidence that the velocity induced by the vortical structures forming a synthetic jet plays an important role in the development of and the velocity field around the jet.

107 Effect of a Synthetic Jet on Cross Flow

2011 ◽  
Vol 2011.46 (0) ◽  
pp. 18-19
Author(s):  
Kiyoshi Otani ◽  
Ryohei Yamamoto
Keyword(s):  
Cross Flow ◽  
Synthetic Jet

The Effect of Orifice Angle and Cavity Dimension on Rectangular Synthetic Jet Actuators

2011 ◽  
Author(s):  
Pooya Kabiri ◽  
Douglas G. Bohl ◽  
Goodarz Ahmadi
Keyword(s):  
Particle Image ◽  
Vortical Structure ◽  
Active Flow Control ◽  
Cross Flow ◽  
Synthetic Jet ◽  
Synthetic Jet Actuators ◽  
Image Velocimetry ◽  
Jet Actuators ◽  
Active Flow ◽  
Analytic Prediction

In the last decade, a great deal of interest has been focused on the application of synthetic jet actuators (SJA) for active flow control. SJAs delay separation by injecting vortex pairs into the cross flow and energizing the turbulent boundary layer. The goal of this study was to investigate the effects of the orifice angle on the performance of axisymmetric SJAs. The SJAs used in this experiment were composed of a piezoelectric (PZT) membrane, cavities and orifices. SJA’s with either a straight (90°) or angled (60°) orifices were characterized using hot-wire anemometry and Particle Image Velocimetry (PIV). It was found that the structure of the jet flow changed depending on the angle of the orifice with differences in the resulting vortical structure observed. The peak jet speed was found to be higher for the straight orifice than for the angled orifice contradicting the analytic prediction based on cavity dimension.

Sign in / Sign up

Export Citation Format

Share Document