Flip-Flop Jet Nozzle

Viets, Hermann

doi:10.2514/3.60550

Cited by 160 publications

(50 citation statements)

References 4 publications

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“…Although fluidic technology has been primarily restricted to enclosed cavities, some of these devices have also been used in free shear flows. Viets (1975) induced spontaneous oscillations in a free rectangular jet by exploiting the concept of a flip-flop actuator. More recently, Raman & Cornelius (1995) used two such jets to impose time-harmonic oscillations in a larger jet by direct impingement.…”

Section: Introductionmentioning

confidence: 99%

Jet vectoring using synthetic jets

2002

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The interaction between a conventional rectangular (primary) air jet and a co-flowing synthetic jet is investigated experimentally. The nozzles of both jets have the same long dimension but the aspect ratio of the synthetic jet orifice is 25 times larger. Detailed particle image velocimetry (PIV) measurements of the flow in the midspan plane show that primary jet fluid is directed into the synthetic jet orifice and the interaction between the jets leads to the formation of a closed recirculating flow domain. The concomitant formation of a low-pressure region between the jets results in deflection of the primary jet toward the actuator jet despite the absence of an extended control surface (e.g. a diffuser or collar) and is balanced by a force on the primary jet conduit. For a given synthetic jet strength and primary jet speed, the vectoring force depends mainly on the volume flow rate of primary jet fluid that is diverted into the synthetic jet actuator. This flow rate is regulated by restricting the flow of entrained ambient fluid using a small streamwise extension of the synthetic jet orifice that scales with the orifice width. The response of the primary jet to the imposed vectoring is investigated using stepped modulation of the driving signal. The characteristic vectoring time and vectoring angle decrease monotonically with primary jet speed.

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Section: Introductionmentioning

confidence: 99%

Jet vectoring using synthetic jets

2002

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“…The fluidic method is considered here and consists of a feedback circuit which produces a jet which flaps from side to side. 3 The main advantage of this system (as with all the unsteady jets) is a more rapid mixing of the jet with the surrounding fluid. The unsteady jet nozzle employed here is shown in Figure 1 and described in detail in Ref.…”

Section: Qualitative Structurementioning

confidence: 99%

“…The unsteady jet nozzle employed here is shown in Figure 1 and described in detail in Ref. 3. The feedback loop is incorporated into the nozzle body to minimize the interference with the coflowing stream.…”

Section: Qualitative Structurementioning

confidence: 99%

Problems in Forced Unsteady Fluid Mechanics.

Viets¹,

Piatt²,

Ball³

et al. 1981

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“…Fluidic oscillatory nozzles as simple and effective mixing devices have been used by Viets (1975). An extension of the fluidic nozzle concept to supersonic flow conditions is described by Bremhorst, Hailye and Rice (1990) and Raman, Hailye and Rice (1993).…”

Section: Introductionmentioning

confidence: 99%

Forced Convection Heat Transfer Enhancement Using a Self-Oscillating Impinging Planar Jet

Camcı

Herr

2002

Journal of Heat Transfer

107

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Impinging jets are widely used in the local enhancement of heat removed from internal passages of gas turbine blades. Arrays of stationary jets are usually impinged on surfaces of internal cooling passages. The current practice is to benefit from the high heat transfer coefficients existing in the vicinity of the jet impingement region on a target wall. The present study shows that a self-oscillating impinging-jet configuration is extremely beneficial in enhancing the heat removal performance of a conventional (stationary) impinging jet. In addition to a highly elevated stagnation line Nusselt number, the area coverage of the impingement zone is significantly enhanced because of the inherent sweeping motion of the oscillating coolant jet. When an oscillating jet (Re=14,000) is impinged on a plate normal to the jet axis (x/d=24 hole to plate distance), a typical enhancement of Nu number on the stagnation line is about 70 percent. The present paper explains detailed fluid dynamics structure of the self-oscillating jet by using a triple decomposition technique on a crossed hot wire signal. The current heat transfer enhancement levels achieved suggest that it may be possible to implement the present self-oscillating-impinging-jet concept in future gas turbine cooling systems, on rotating disks, glass tempering/quenching, electronic equipment cooling, aircraft de-icing, combustors and heat exchangers.

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Flip-Flop Jet Nozzle

Cited by 160 publications

References 4 publications

Jet vectoring using synthetic jets

Jet vectoring using synthetic jets

Problems in Forced Unsteady Fluid Mechanics.

Forced Convection Heat Transfer Enhancement Using a Self-Oscillating Impinging Planar Jet

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