Effect of slotted exit orifice on performance of plasma synthetic jet actuator

Zong, Haohua; Kotsonis, Marios

doi:10.1007/s00348-016-2299-1

Cited by 33 publications

(17 citation statements)

References 45 publications

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“…From time t=60 µs to t=120 µs, the density gradient is largely increased because of the hot gas exhausting from the cavity, and the gradual increase of the front vortex ring can be observed. As it was reported for PSJA [11], at a certain time (here t=120 µs) the front vortex ring evolves into a spherical vortex. One can notice that up to time t=180 µs the jet flow presents two distinct regions whose are differentiated by the intensity of the density spatial gradient.…”

Section: B Observations By Time-resolved Schlierensupporting

confidence: 66%

New pulsed jet using spark plasma discharge: Subsonic configuration

Bénard

Zong

Zhang

et al. 2020

AIAA Scitech 2020 Forum

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Active flow control is demanding for new actuation technologies as none of the actual available actuators has reached all the criterions for expecting an implementation in the coming years. Here, a new type of pulsed jet is designed and preliminary measurements of its performances in quiescent flow are conducted. Pulsed operation has been chosen because of the expected high efficiency of pulsed actuation in comparison to continuous blowing. The traditional pulsed jets being limited in term of frequency because of the use of a mechanical valve to achieve the desired pneumatic opening and closing of a jet provided by an external pressure source, the fast response of electrical discharge is exploited in the present investigation. The objective is to modulate the output of a small jet exhausting from a pressurized chamber. A spark discharge is used to affect the thermodynamic state of the gas in order to electrically achieve periodic cancellation of the chocked flow conditions at the throat upstream the jet exit. In the present study, such actuator with additional neck extension and jet diameter enlargement is investigated. The configuration results in a high-speed subsonic jet whose velocity amplitude is modified by an arc discharge with deposited energy from 18 to 780 mJ. Some characteristics of the jet are provided using optical methods such as high-speed Schlieren and PIV. In particular, it is shown that the jet flow velocity can be increased from 50 m.s-1 to 190 m.s-1 .

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Section: B Observations By Time-resolved Schlierensupporting

confidence: 66%

New pulsed jet using spark plasma discharge: Subsonic configuration

Bénard

Zong

Zhang

et al. 2020

AIAA Scitech 2020 Forum

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“…Year Type Application Reynolds Number Advantage(s) [57] 2017 Microjet Wind turbine 1,000,000 Increased pressure coefficient [57] 2017 Microjet Wind turbine 1,000,000 Increased lift [58] 2017 VGJ Low-pressure turbine 50,000-300,000 Max 75% reduction in total pressure loss [9] 2016 VGJ, deflected TE Low pressure turbine 20,000; 50,000 12.5% reduction in solidity [23] 2016 VGJ, steady Gas turbines 840,000 Reduced corner vortices, 14% reduction in total pressure loss [59] 2014 Microjet Wind turbine 1,000,000 Increased lift [60] 2013 Microjet Low pressure turbine 50,000 Max 85% reduction in wake-loss coefficient [12] 2013 Pulsating jet Stemme S10 motor glider 1,750,000 30% increase in lift-to-drag ratio [61] 2012 VGJ, unsteady Low pressure turbine 25,000; 50,000 Separation control [62] 2011 VGJ, unsteady Low pressure turbine Induced reattachment [63] 2011 VGJ, unsteady Low pressure turbine 25,000; 50,000 Separation control, increased lift, reduced total pressure loss [64] 2009 VGJ, unsteady Airfoil SS 7700 (Re θ ) Delayed separation [65] 2004 VGJ, steady Low pressure turbine 25,000 Max 50% reduction in total pressure loss [65] 2004 VGJ, unsteady Low pressure turbine 25,000 Max 40-50% reduction in total pressure loss Outcome: Controlled separation, induced reattachment Nowadays, the SDBDAs are used more than the SCDAs since they provide more stable discharge [15], and AC operation results in lower voltage requirement [18] and low power consumption (order of watts) [66]. On the other hand, the SDBDA may suffer from high peaks of electric input power under certain conditions; however, this may be reduced by using inductive filters between the power supply and the actuator [15].…”

Section: Refmentioning

confidence: 99%

“…The fluid is ingested towards the actuator and ejected as a jet to the main flow. The advantage of the plasma synthetic jet actuators is acceptable power consumption (order of 100 W) [66]. The experimental results of Neretti et al [68] indicated that the annular plasma synthetic jet actuator exhibits better performance than the linear version.…”

Section: Refmentioning

confidence: 99%

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Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

Tiainen

Grönman

Jaatinen-Värri

et al. 2017

IJTPP

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Abstract:The decrease in the performance of centrifugal compressors operating at low Reynolds numbers (e.g., unmanned aerial vehicles at high altitudes or small turbomachines) can reach 10% due to increased friction. The purposes of this review are to represent the state-of-the-art of the active and passive flow control methods used to improve performance and/or widen the operating range in numerous engineering applications, and to investigate their applicability in low-Reynolds-number centrifugal compressors. The applicable method should increase performance by reducing drag, increasing blade loading, or reducing tip leakage. Based on the aerodynamic and structural demands, passive methods like riblets, squealers, winglets and grooves could be beneficial; however, the drawbacks of these approaches are that their performance depends on the operating conditions and the effect might be negative at higher Reynolds numbers. The flow control method, which would reduce the boundary layer thickness and reduce wake, could have a beneficial impact on the performance of a low-Reynolds-number compressor in the entire operating range, but none of the methods represented in this review fully fulfil this objective.

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“…This effect is considered by Zong & Kotsonis (2017), and the peak measurement error yielded is modelled as a function of the ratio of laser sheet thickness to orifice diameter. For the investigated case, the peak relative error is estimated to be 8.3 %.…”

Section: Appendix: Piv Measurement Uncertaintymentioning

confidence: 99%

Interaction between plasma synthetic jet and subsonic turbulent boundary layer

Zong

Kotsonis

2017

Physics of Fluids

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This paper experimentally investigates the interaction between a plasma synthetic jet (PSJ) and a subsonic turbulent boundary layer (TBL) using a hotwire anemometer and phase-locked particle imaging velocimetry. The PSJ is interacting with a fully developed turbulent boundary layer developing on the flat wall of a square wind tunnel section of 1.7 m length. The Reynolds number based on the freestream velocity (U∞ = 20 m/s) and the boundary layer thickness (δ99 = 34.5 mm) at the location of interaction is 44 400. A large-volume (1696 mm3) three-electrode plasma synthetic jet actuator (PSJA) with a round exit orifice (D = 2 mm) is adopted to produce high-speed (92 m/s) and short-duration (Tjet = 1 ms) pulsed jets. The exit velocity variation of the adopted PSJA in a crossflow is shown to remain almost identical to that in quiescent conditions. However, the flow structures emanating from the interaction between the PSJ and the TBL are significantly different from what were observed in quiescent conditions. In the midspan xy plane (z = 0 mm), the erupted jet body initially follows a wall-normal trajectory accompanied by the formation of a distinctive front vortex ring. After three convective time scales the jet bends to the crossflow, thus limiting the peak penetration depth to approximately 0.58δ99. Comparison of the normalized jet trajectories indicates that the penetration ability of the PSJ is less than steady jets with the same momentum flow velocity. Prior to the jet diminishing, a recirculation region is observed in the leeward side of the jet body, experiencing first an expansion and then a contraction in the area. In the cross-stream yz plane, the signature structure of jets in a crossflow, the counter-rotating vortex pair (CVP), transports high-momentum flow from the outer layer to the near-wall region, leading to a fuller velocity profile and a drop in the boundary layer shape factor (1.3 to 1.2). In contrast to steady jets, the CVP produced by the PSJ exhibits a prominent spatiotemporal behaviour. The residence time of the CVP is estimated as the jet duration time, while the maximum extent of the affected flow in the three coordinate directions (x, y, and z) is approximately 32D, 8.5D, and 10D, respectively. An extremely high level of turbulent kinetic energy production is shown in the jet shear-layer, front vortex ring, and CVP, of which the contribution of the streamwise Reynolds normal stress is dominant. Finally, a conceptual model of the interaction between the PSJ and the TBL is proposed.

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Effect of slotted exit orifice on performance of plasma synthetic jet actuator

Cited by 33 publications

References 45 publications

New pulsed jet using spark plasma discharge: Subsonic configuration

New pulsed jet using spark plasma discharge: Subsonic configuration

Flow Control Methods and Their Applicability in Low-Reynolds-Number Centrifugal Compressors—A Review

Interaction between plasma synthetic jet and subsonic turbulent boundary layer

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