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

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

Stationary cross-flow breakdown in a high-speed swept-wing boundary layer

2021 ◽  
Vol 33 (2) ◽  
pp. 024108
Author(s):  
Jianqiang Chen ◽  
Siwei Dong ◽  
Xi Chen ◽  
Xianxu Yuan ◽  
Guoliang Xu
Keyword(s):  
Boundary Layer ◽  
High Speed ◽  
Cross Flow ◽  
Swept Wing

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.

The Calculation of Three-Dimensional Turbulent Boundary Layers: Part I: Flow over the Rear of an Infinite Swept Wing

1967 ◽  
Vol 18 (1) ◽  
pp. 55-84 ◽  
Author(s):  
N. A. Cumpsty ◽  
M. R. Head
Keyword(s):  
Essential Feature ◽  
Three Dimensional ◽  
Cross Flow ◽  
Stream Velocity ◽  
Pressure Gradients ◽  
Swept Wing ◽  
Form Parameter ◽  
Method Of Calculation ◽  
Flow Profiles ◽  
Momentum Integral

SummaryA method of calculation has been developed in which all terms in the momentum integral equations in the streamwise and cross-flow directions are taken into account so that no restriction to small cross-flows is imposed. The essential feature of the method is the use of an entrainment equation which enables the development of the streamwise form parameter to be calculated along with the streamwise and cross-flow momentum thicknesses. Mager’s quadratic expression is used to relate streamwise and cross-flow profiles. The method has been applied to the idealised case of an infinite swept wing with free-stream velocity over the forward part of the chord and a linear adverse velocity gradient over the rear. The position of separation, the directions of the surface streamlines and the development of streamwise and cross-flow profiles have been calculated for a series of angles of sweep and for adverse pressure gradients of varying severity.

Control of a swept-wing boundary layer using ring-type plasma actuators

2018 ◽  
Vol 844 ◽  
pp. 36-60 ◽  
Author(s):  
Nima Shahriari ◽  
Matthias R. Kollert ◽  
Ardeshir Hanifi
Keyword(s):  
Boundary Layer ◽  
Cross Flow ◽  
Plasma Actuators ◽  
Swept Wing ◽  
Ring Type ◽  
Transition Control ◽  
Turbulent Transition ◽  
Roughness Elements ◽  
Order Of Magnitude ◽  
Induced Velocity

Application of ring-type plasma actuators for control of laminar–turbulent transition in a swept-wing boundary layer is investigated thorough direct numerical simulations. These actuators induce a wall-normal jet in the boundary layer and can act as virtual roughness elements. The flow configuration resembles experiments by Kim et al. (2016 Technical Report. BUTERFLI Project TR D3.19, http://eprints.nottingham.ac.uk/id/eprint/46529). The actuators are modelled by the volume forces computed from the experimentally measured induced velocity field at the quiescent air condition. Stationary and travelling cross-flow vortices are triggered in the simulations by means of surface roughness and random unsteady perturbations. Interaction of vortices generated by actuators with these perturbations is investigated in detail. It is found that, for successful transition control, the power of the actuators should be increased to generate jet velocities that are one order of magnitude higher than those used in the experiments by Kim et al. (2016) mentioned above.

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.

Sign in / Sign up

Export Citation Format

Share Document