Plasma-based active closed-loop control of instability waves in unexcited turbulent jet. Part 2. Installed jet.

Faranosov, G. A.; Kopiev, V. F.; Bychkov, O. P.; Moralev, I. A.; Kazansky, Pavel

doi:10.2514/6.2019-2558

Cited by 6 publications

(4 citation statements)

References 37 publications

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“…This coherence length allows the sensor to partially estimate their upstream components, which can thus be cancelled by the actuator. It is speculated that a similar mechanism is responsible for the control of a jet (a convectively unstable flow, as the present example) using downstream sensors obtained by [74] and [75]. An extreme example is when the flow is excited with a harmonic, rank-1, forcing: forces and flow response have infinite coherence lengths, and can thus be estimated and controlled based on only a few sensor readings, from which amplitudes and phases are extracted.…”

Section: Control With a Single Sensormentioning

confidence: 95%

Resolvent-based tools for optimal estimation and control via the Wiener-Hopf formalism

Martini,

Jung,

Cavalieri

et al. 2022

Preprint

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The application of control tools to complex flows frequently requires approximations, such as reduced-order models and/or simplified forcing assumptions, where these may be considered low-rank or defined in terms of simplified statistics (e.g. white noise). In this work, we propose a resolvent-based control methodology with causality imposed via a Wiener-Hopf formalism. Linear optimal causal estimation and control laws are obtained directly from full-rank, globally stable systems with arbitrary disturbance statistics, circumventing many drawbacks of alternative methods. We use efficient, matrix-free methods to construct the matrix Wiener-Hopf problem, and we implement a tailored method to solve the problem numerically. The approach naturally handles forcing terms with space-time colour; it allows inexpensive parametric investigation of sensor/actuator placement in scenarios where disturbances/targets are low rank; it is directly applicable to complex flows disturbed by high-rank forcing; it has lower cost in comparison to standard methods; it can be used in scenarios where an adjoint solver is not available; or it can be based exclusively on experimental data. The method is particularly well-suited for the control of amplifier flows, for which optimal control approaches are typically robust. Validation of the approach is performed using the linearized Ginzburg-Landau equation. Flow over a backward-facing step perturbed by high-rank forcing is then considered. Sensor and actuator placement are investigated for this case, and we show that while the flow response downstream of the step is dominated by the Kelvin-Helmholtz mechanism, it has a complex, high-rank receptivity to incoming upstream perturbations, requiring multiple sensors for control.

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Section: Control With a Single Sensormentioning

confidence: 95%

Resolvent-based tools for optimal estimation and control via the Wiener-Hopf formalism

Martini,

Jung,

Cavalieri

et al. 2022

Preprint

View full text Add to dashboard Cite

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“…We emphasise, however, that we focus on jets with fully turbulent boundary layers; our goal is thus to control turbulent disturbances, and should not be thought of as a transition delay mechanism. An important step towards this goal has been made in the works of Kopiev et al [86] and Bychkov et al [87], wherein harmonically-forced disturbances have been controlled in turbulent jets through wave cancellation.…”

Section: B Application To Turbulent Jetsmentioning

confidence: 99%

Real-time reactive control of stochastic disturbances in forced turbulent jets

et al. 2021

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In this work we perform reactive control of stochastic disturbances in forced turbulent jets based on destructive interference. The study is motivated by the success of recent studies in applying this type of control on instability waves in transitional boundary layers and free-shear flows. Linear convective mechanisms in the initial region of turbulent jets are explored in order to perform reactive control, wherein the actuation signal is updated in real time based on sensor measurements performed upstream, resulting in an inverse feedforward approach. The control law is based on empirical transfer functions of the jet response to stochastic forcing and actuation, which are measured experimentally. Since turbulent jets have energy content spread in a number of azimuthal wavenumbers, we apply axisymmetric forcing at the nozzle lip in order to be able to perform control using a reduced number of sensors and actuators. The external forcing produces axisymmetric wavepackets which possess stochastic phases and amplitudes, akin to turbulent fluctuations found in unforced jets. We demonstrate the successful implementation of real-time reactive control of these disturbances, achieving order-of-magnitude attenuations of associated velocity fluctuations. Control is shown to reduce fluctuation levels over an extensive streamwise range.

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“…Studies on active control of installation noise, on the other hand, are more scarce. To the best of the authors' knowledge, the literature is limited to two studies (Bychkov et al, 2019;Kopiev et al, 2020), where they investigate the use of plasma actuators for controlling instabilities in jets, leading to a reduction in the installation noise. In this study, we explore the potential of an alternative active control strategy based on actuation at the TE of a solid surface.…”

Section: Introductionmentioning

confidence: 99%

Modeling closed-loop control of installation noise using Ginzburg-Landau equation

Karban¹,

Martini²,

Jordan³

2023

Preprint

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Installation noise is a dominant source associated with aircraft jet engines. Recent studies show that linear wavepacket models can be employed for prediction of installation noise, which suggests that linear control strategies can also be adopted for mitigation of it. We present here a simple model to test different control approaches and highlight the potential restrictions on a successful noise control in an actual jet. The model contains all the essential elements for a realistic representation of the actual control problem: a stochastic wavepacket is obtained via a linear Ginzburg-Landau model; the effect of the wing trailing edge is accounted for by introducing a semi-infinite half plane near the wavepacket; and the actuation is achieved by placing a dipolar point source at the trailing edge, which models a piezoelectric actuator. An optimal causal resolvent-based control method is compared against the classical wave-cancellation method. The effect of the causality constraint on the control performance is tested by placing the sensor at different positions. We demonstrate that when the sensor is not positioned sufficiently upstream of the trailing edge, which can be the case for the actual control problem due to geometric restrictions, causality reduces the control performance. We also show that this limitation can be moderated using the optimal causal control together with modelling of the forcing.

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Plasma-based active closed-loop control of instability waves in unexcited turbulent jet. Part 2. Installed jet.

Cited by 6 publications

References 37 publications

Resolvent-based tools for optimal estimation and control via the Wiener-Hopf formalism

Resolvent-based tools for optimal estimation and control via the Wiener-Hopf formalism

Real-time reactive control of stochastic disturbances in forced turbulent jets

Modeling closed-loop control of installation noise using Ginzburg-Landau equation

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