PIV Measurements of the Effect of Pitch and Skew on a Circular Orifice Synthetic Jet in a Turbulent Boundary Layer

Garcillan, Luis; Liddle, Stephen; Sunneechurra, Kailash; Crowther, William; Zhong, Shan; Wood, N. J.

doi:10.2514/6.2006-318

Cited by 4 publications

(4 citation statements)

References 11 publications

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“…Each strategy generates a different SJA design, namely in the selection of the orifice height h. For the velocity-optimised SJA, h ¼ 2.1d 31 and for the vorticity-optimised SJA, h ¼ 0.5d to maximise the strength of vortex rollup. 40 The latter SJA design also includes optional settings for orifice pitch ( ¼ 45 ) and skew ( ¼ 90 ) to maximise vorticity bias for improved separation control effectiveness, 42 which is applicable for regions where the sign of the boundary layer vorticity is also biased, e.g. on a swept wing model.…”

Section: Development Of An Actuator Array Design Methodologymentioning

confidence: 99%

Development of design methodology for a synthetic jet actuator array for flow separation control applications

Jabbal

Liddle

Potts

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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This article documents the development of synthetic jet actuator array hardware to augment high-lift system effectiveness in a wind tunnel model. The study involved the design, manufacture and bench test of a synthetic jet actuator array based on an inclined actuator configuration to reduce volume installation requirements without a loss in jet velocity relative to a non-inclined baseline model; incorporation of proper synthetic jet actuator systems wiring and internal synthetic jet actuator chamber pressure-sensing for actuator health monitoring. The peak velocity obtained from the inclined synthetic jet actuator array was 100 m/s, which favourably compares to the baseline array ($90 m/s), while reducing the usable depth requirements by 50%. The final outcome of this study has been to apply the design lessons learned to develop a methodology for designing a synthetic jet actuator array with the constraints of using piezoelectricbased actuator technology for flow separation control applications.

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Section: Development Of An Actuator Array Design Methodologymentioning

confidence: 99%

Development of design methodology for a synthetic jet actuator array for flow separation control applications

Jabbal

Liddle

Potts

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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“…Earlier experience with variations in the injection angle (e.g. Garcillan et al 2006) suggest that injection at a shallow angle, in the direction of the flow, is the most effective, in so far as it generates strong and longlived streamwise vortices. The physical scenario proposed is that the realignment of the jet is modest, thus securing a high level of coherence of the vortical secondary motion over a longer streamwise distance.…”

Section: Effect Of Injection Anglementioning

confidence: 99%

“…The interaction between round (or square) jets and attached turbulent boundary layers has been studied experimentally by Gordon & Soria (2002), Schaeffler & Jenkins (2006), Zaman & Milanovic (2002) and Garcillan et al (2006), while computational investigations include those of Ravi, Mittal & Najjar (2004), Dandois, Garnier & Sagaut (2006) and Wu & Leschziner (2009), the first restricted to verylow-Reynolds-number laminar conditions and the last two being fully turbulent and corresponding to the experiments of Schaeffler & Jenkins (2006) and Garcillan et al S. Lardeau and M. A. Leschziner (2006), respectively. Most of these studies are moderately pertinent to the present paper, in so far as they quantify the effect of the actuation on the boundary layer downstream of the orifice, within a region that lies upstream of the separation line, as is the case in the flow which is the subject of this study.…”

Section: Introductionmentioning

confidence: 99%

The interaction of round synthetic jets with a turbulent boundary layer separating from a rounded ramp

Lardeau

Leschziner

2011

J. Fluid Mech.

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A computational large eddy simulation (LES) study is presented of the interaction between a turbulent boundary layer separating from a rounded ramp in a duct and a pair of spanwise-periodic, round synthetic jets, actuated upstream of the nominal separation line. Several scenarios are considered, for different injection angles and velocity ratios. In all cases, the actuation frequency corresponds to the sheddinginstability mode of the separated shear layer. Experimental data, available for both the baseline flow and one actuated configuration, are used to verify the validity of the computational solutions. The analysis includes a separation of coherent and stochastic contributions to the time-averaged statistics of the auto-and cross-correlations of the fluctuations. The control authority is examined by reference to the effects of the actuation on the size of the separated zone, the momentum thickness of the boundary layer, the velocity field, various turbulence quantities and phase-averaged properties. The study demonstrates that the principal aspect of the interaction, at mean-flow level, is an increase in mixing provoked by the formation of strong streamwise vortices away from the wall, the induction of much weaker streamwise vortices close to the wall, and the extra production of stochastic turbulence caused by unsteady straining. The coherent stresses arising from the periodic perturbations are high -typically 5 times the levels of the unperturbed flow -but only within about 5-7 diameters of the jet orifice, and 2 orifice diameters on each side of the jet, and these are dominant primarily in the outer parts of the boundary layer. Stochastic turbulence is also elevated, but more modestly. The global effect of the actuation is a reduction of 10-20 % in the length of the separated region and 20-40 % in the thickness of the reverse-flow layer, depending on the actuation scheme, counter-flow actuation being the most effective. This reduction is mainly associated with a delay in separation. These results highlight the need for synthetic jets to be placed close to the separation zone and for the inter-jet distance to be of order 5 or lower to achieve a high level of separation-control authority.

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“…The outcome of this research programme has led to the development of the first methodology for designing synthetic-jet actuators at full-scale flight conditions. In this research programme, synthetic jets issued from both circular orifices of different orientations and rectangular orifices of different aspect ratios have also been studied [19][20][21]. However, in order to ensure the coherence of the content of this paper, only the research results obtained on synthetic jets issued from normal circular orifices will be presented.…”

mentioning

confidence: 98%

Towards the Design of Synthetic-jet Actuators for Full-scale Flight Conditions

Zhong

Jabbal

Tang

et al. 2007

Flow Turbulence Combust

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Despite the proven capability of synthetic-jet actuators in delaying boundarylayer separation in laboratory experiments, a capability that allows the geometry and operating conditions of these devices to be designed and selected for maximum flowcontrol effectiveness in full-scale flight conditions has yet to be developed. In this twopart paper, the key results obtained during a 3-year research programme aiming at establishing such a capability based on a better understanding of the fluid mechanics of synthetic jets and an improved modelling capacity are reported. In Part 1 of this paper, the experimental studies of the behaviour of synthetic jets in both quiescent flow and a boundary layer are described. The work has led to an improved understanding of the dimensionless parameters that determine the formation and development of vortex rollup and how the strength of rollup can be enhanced by optimizing the geometry and operating condition. Based on the study of the nature of vortical structures produced as the result of the interaction with a boundary layer and their impact in the near-wall region where flow control is desired, the conditions for producing effective vortical structures for delaying flow separation were established. The finding from this work forms the basis of a number of criteria used for designing synthetic jet actuators for full-scale flight condition to be presented in Part 2.

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PIV Measurements of the Effect of Pitch and Skew on a Circular Orifice Synthetic Jet in a Turbulent Boundary Layer

Cited by 4 publications

References 11 publications

Development of design methodology for a synthetic jet actuator array for flow separation control applications

Development of design methodology for a synthetic jet actuator array for flow separation control applications

The interaction of round synthetic jets with a turbulent boundary layer separating from a rounded ramp

Towards the Design of Synthetic-jet Actuators for Full-scale Flight Conditions

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