Publications
Nonlinear dynamics and thermoacoustic intermittency of a hydrogen-powered sequential combustor
M. Impagnatiello, S. Shcherbanev, B. Dharmaputra, N. Noiray
Combustion and Flame vol. 274 (2025), pp. 114008
This study experimentally investigates the coupling between thermoacoustic instabilities and autoignition kernel formation in Constant Pressure Sequential Combustors (CPSCs). Two fuel types are examined: a less reactive methane–hydrogen blend and pure hydrogen. By increasing the thermal power of the first stage, thermoacoustic instabilities arise in both configurations, albeit with distinct behaviors. [...]
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Flame transfer function measurement of a sequential combustor fuelled with natural gas and hydrogen
B. Dharmaputra, P. Nagpure, M. Impagnatiello, N. Noiray
Combustion and Flame vol. 274 (2025), pp. 113972
The flame transfer function (FTF) relates acoustic perturbations and the coherent heat release rate response. This frequency-dependent function governs the thermoacoustic stability of a combustor. The FTF measurement is therefore of great interest for predicting the stability of the practical combustor connected to the engine’s compressor and turbine. So far, the FTFs of the second stage of constant pressure sequential combustors (CPSC) have only been obtained from numerical simulations. [...]
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Phase-cancellation of velocity oscillations in a flow duct using a slow-sound metamaterial
R. Martin, K. Pandey, B. Schuermans, N. Noiray
J. Sound. Vib. Vol 596 (2025), pp. 118774.
Self-sustained acoustic oscillations in industrial systems with mean flow can cause unwanted vibrations or noise pollution. Acoustic metamaterials can be engineered and integrated in such systems to prevent these limit cycles. In this study, an acoustic metamaterial is proposed for decreasing the acoustic admittance at the outlet of a contraction in a pipe. It can reduce velocity oscillations by more than 50%, without requiring an enlargement of the pipe or increasing the static resistance to the mean flow significantly. [...]
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BOATS: Bayesian optimization for active control of thermoacoustics
B.Dharmaputra, P. Reckinger, B. Schuermans, and N. Noiray
Journal of Sound and Vibration, Vol. 582, 2024
This investigation presents novel adaptive control algorithms specifically designed to address and mitigate thermoacoustic instabilities. Gas turbines are limited in their operational range due to thermoacoustic instability. Two control strategies are available to alleviate this issue: active and passive. Active control strategies have a wider flexibility than passive control strategies because they can adapt to the operating conditions of the gas turbine. [...]
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Numerical Study of Ignition and Combustion of Hydrogen-Enriched Methane in a Sequential Combustor
M.Impagnatiello, Q.Malé and N.Noiray
Flow, Turbulence and Combustion, Vol. 112, 2024
The ignition and combustion behavior in the second stage of a sequential combustor are numerically investigated at atmospheric pressure using Large Eddy Simulations (LES) for pure CH4 and two CH4-H2 fuel blends with mass ratios of 24:1 and 49:1, respectively. As the H2 content increases, the combustion dynamics undergo significant changes, characterized by the formation of multiple autoignition kernels upstream of the main flame front. This behavior is promoted by the large mass fraction of OH radicals in the flow entering the second stage, which is approximately an order of magnitude higher than that at chemical equilibrium and substantially enhances autoignition. [...]
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Numerical study of nitrogen oxides chemistry during plasma assisted combustion in a sequential combustor
Q. Malé, N. Barléon, S. Shcherbanev, B. Dharmaputra and N. Noiray
Combustion and Flame, Vol. 260, 2024
Plasma Assisted Combustion (PAC) is a promising technology to enhance the combustion of lean mixtures prone to instabilities and flame blow-off. Although many PAC experiments demonstrated combustion enhancement, several studies report an increase in NOx emissions. The aim of this study is to determine the kinetic pathways leading to NOx formation in the second stage of a sequential combustor assisted by Nanosecond Repetitively Pulsed Discharges (NRPDs). For this purpose, Large Eddy Simulation (LES) associated with an accurate description of the combustion/NOx chemistry and a phenomenological model of the plasma kinetics is used. [...]
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A deep operator network for Bayesian parameter identification of self-oscillators
T. Sugandi, B. Dharmaputra, and N. Noiray
Data-Centric Engineering, Vol. 5, 2024
Many physical systems exhibit limit-cycle oscillations that can typically be modeled as stochastically driven self-oscillators. In this work, we focus on a self-oscillator model where the nonlinearity is on the damping term. In various applications, it is crucial to determine the nonlinear damping term and the noise intensity of the driving force. This article presents a novel approach that employs a deep operator network (DeepONet) for parameter identification of self-oscillators. [...]
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Acoustic scattering of a sequential combustor controlled with non-equilibrium plasma: a numerical study
M.Impagnatiello, Q.Malé, and N. Noiray
Proceedings of the Combustion Institute, Vol. 40, 2023
The impact of Nanosecond Repetitively Pulsed Discharges (NRPDs) on the acoustic scattering properties of the second stage of a Constant Pressure Sequential Combustor (CPSC) is investigated using Large Eddy Simulations (LESs) with state-of-the-art plasma modeling, combined with methods from System Identification. The results demonstrate that plasma-generated ignition kernels significantly mitigate the system's acoustic power amplification by inducing heat release fluctuations that are out of phase with local pressure fluctuations. [...]
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Stabilization of a thermoacoustically unstable sequential combustor using non-equilibrium plasma: Large eddy simulation and experiments
Q. Male, S. Shcherbanev, M. Impagnatiello, N. Noiray
Proc. Combust. Inst 40 (2024), pp. 105277
Plasma-assisted combustion using Nanosecond Repetitively Pulsed Discharges (NRPDs) is an emerging technology that enhances the reactivity of fuel–air mixtures, offering significant improvements in operational and fuel flexibility—two crucial features for future sustainable gas turbines. The mechanisms that enable the stabilization of thermoacoustically unstable burners, however, remain unclear. Thus, to investigate the physical phenomena involved, we performed a massively parallel Large Eddy Simulation (LES) of the stabilization of a thermoacoustically unstable sequential combustor by NRPDs at atmospheric pressure. [...]
Identification of entropy waves in a partially premixed combustor
A. J. Eder, B. Dharmaputra, A.M. Garcia, C. F. Silva, W. Polifke
Proc. Combust. Inst 40 (2024), pp. 105609
Unsteady combustion generates not only acoustic waves, but also fluctuations of the burnt gas temperature — referred to as entropy waves. These waves are convected by the mean flow through the combustor and result in conversion to acoustic energy when accelerated in an exit nozzle. The upstream traveling acoustic wave can then couple with the unsteady heat release of the flame and cause self-excited thermoacoustic instability, particularly at low frequencies (“rumble”). [...]
Plasma assisted thermoacoustic stabilization of a transiently operated sequential combustor at high pressure
B.Dharmaputra, S. Shcherbanev, and N. Noiray
Proceedings of the Combustion Institute, Vol. 40, 2023
This study demonstrates the stabilization of a thermoacoustic instability in a sequential combustor at elevated pressure conditions using Nanosecond Repetitively Pulsed Discharges (NRPD). Sequential combustors operating at constant pressure offer several advantages over their conventional counterparts, including increased fuel flexibility and a wider operating range. In this work, we investigate the control of thermoacoustic instabilities with NRPD up to 6 bar, in both stationary and transient modes of operation. [...]
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Thermoacoustic stabilization of a sequential combustor with ultra-low-power nanosecond repetitively pulsed discharges
B. Dharmaputra, S. Shcherbanev, B. Schuermans and N. Noiray
Combustion and Flame, vol. 258, pp. 113101, 2023
This work demonstrates the stabilization of an atmospheric sequential combustor with NRPD with a plasma power of 1.5 x 10^-3 percent of the thermal power of the flames. This marks a foundational stepping stone in the real implementation of such technology in gas turbines. [...]
Generation of Entropy Waves by Fully Premixed Flames in a Non-Adiabatic Combustor With Hydrogen Enrichment
A. J. Eder, B. Dharmaputra, M. Désor, C.F. Silva, A.M. Garcia, B. Schuermans, N. Noiray, W. Polifke
J. Eng. Gas Turbines Power. Nov 2023, 145, pp 111001
Thermoacoustic combustion instability is a major concern in gas turbine combustors with hydrogen-enriched fuels. Unsteady combustion not only generates acoustic waves but it may also result in fluctuations of burnt gas temperature, referred to as entropy waves. They are convected by the mean flow through the combustor and can cause indirect combustion noise when they are accelerated at the exit. [...]
Air-blast atomization and ignition of a kerosene spray in hot vitiated crossflow
L. Miniero, K. Pandey, D. Fredrich, S. Shcherbanev, U. Doll, A. Giusti and N. Noiray
Combustion and Flame, Vol. 256, 2023
Promising concepts based on moderate or intense low-oxygen dilution (MILD) combustion have been investigated in academia and industry. This MILD regime can be obtained from the recirculation of the hot vitiated combustion products to raise the temperature of the reactants, resulting in distributed reaction regions and lower flame temperatures. In the present work, we consider the air-blast atomization of a kerosene spray in crossflow, which enables efficient mixing between fuel and oxidizer [...]
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Failure of thermoacoustic instability control due to periodic hot gas ingestion in Helmholtz dampers
L. Miniero, G. A. Mensah, C. Bourquard and N. Noiray
Journal of Sound and Vibration, Vol. 548, 2023
The periodic ingestion of the combustion chamber hot gas in the resonant cavity of Helmholtz dampers can be a serious issue, if not considered in the design phase of these devices. This study presents experimental and theoretical investigations of that problem. A physics-based model is derived with a few empirical parameters, calibrated with data which were collected from an experimental setup comprising a tunable Helmholtz damper connected to a combustor operated at atmospheric pressure. [...]
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Effect of Mixing on the Anchoring and Combustion Regimes of Pure Hydrogen Flames in Sequential Combustors
R. Solana-Perez, S.A. Shcherbanev, A.Ciani, N.Noiray
Journal of Engineering for Gas Turbines and Power 145, pp. 031026
In this work we perform an experimental study of the combustion of pure hydrogen in the sequential stage of a generic combustor. This academic test rig is a simplified model of an industrial sequential combustor. The sequential fuel is injected using different injector geometries. The composition and temperature of the hot stream at the inlet of the sequential burner are defined by the mass flows of the hot combustion products from the first stage (30 kW natural gas-air flame with equivalence ratio of 0.7) and of the dilution air. [...]
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The Rayleigh integral is always positive in steadily operated combustors
B. Schuermans, J. Moeck, A. Blondé, B. Dharmaputra and N. Noiray
Proceedings of the Combustion Institute, Vol. 39, 2022
The Rayleigh index has been used for decades by a large number of researchers as an indicator to determine if a flame is driving or damping thermoacoustic interaction mechanisms. It is commonly assumed in literature that the sign of the Rayleigh index from steady state data can be used to determine if the thermoacoustic feedback loop is stabilizing or destabilizing. However, we show in this paper that under fairly general conditions, a correctly measured Rayleigh index is always positive if evaluated from statistically stationary data. [...]
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Combustion regime transition of H2 flames during steady and transient operation of a sequential combustor
R. Solana-Pérez, S. A. Shcherbanev, B. Dharmaputra, A. Ciani and N. Noiray
Proceedings of the Combustion Institute, Vol. 39, 2022
The combustion regime transition in a sequential burner (SB) supplied with H2 (48 kW) is experimentally studied during steady and transient operation. The test rig is a simplified model of an industrial sequential combustor featuring two-staged combustion chambers separated by a mixing section in which dilution air and fuel are injected. The temperature, velocity and composition of the hot vitiated gas flowing through the SB are defined by the products from the first stage (30 kW natural gas-air flame at equivalence ratio 0.7), and by the mass flow of dilution air. [...]
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Entropy transfer function measurement with tunable diode laser absorption spectroscopy
B.Dharmaputra, S. Shcherbanev, Audrey Blonde, Bruno Schuermans, Nicolas Noiray
Proc Combust Inst, vol 39, pp. 4621-4630, 2023
In this work, a temperature sensor based on laser absorption spectroscopy is developed and evaluated in a single stage combustor. This sensor is particularly important to quantify the effect of temperature fluctuation in the sequential mixing channel on the sequential flame.
Numerical study of plasma assisted combustion in a sequential combustor
Q. Malé, S. A. Shcherbanev and N. Noiray
Proceedings of the Combustion Institute, Vol. 39, 2022
In addition to establishing a numerical framework for plasma-assisted combustion simulations, this work clarifies the kinetic effects of NRP discharges on the initiation of reactive kernels in the sequential burner.
Effect of plasma-flow coupling on the ignition enhancement with non-equilibrium plasma in a sequential combustor
S. A. Shcherbanev, Q. Malé, B. Dharmaputra, R. Solana-Pérez and N. Noiray
Journal of Physics D: Applied Physics, Vol. 55, 2022
This paper presents crucial insights into the absolute values of plasma parameters, including the dynamics of rapid gas heating and electron number density, during nanosecond spark discharges within a hot vitiated flow. Additionally, it explores the coupling between discharge geometry and dynamics, with a focus on the pulse repetition frequency dependence. The study systematically investigates the efficiency of flame initiation and enhancement with Nanosecond Repetitively Pulsed Discharges (NRPD) across varying reactivity levels of the sequential flame. These findings constitute a pivotal step toward comprehending the impact of NRPD on the dynamics of sequential flames, contributing significantly to the understanding of the mechanisms involved in stabilizing thermoacoustically unstable combustors.
Jetting axial flow induced by nanosecond repetitively pulsed discharges in quiescent ambient air
S. A. Shcherbanev, T. Krzymuski, Y. Xiong, N. Noiray
Journal of Physics D: Applied Physics, 55(38), 385202.
This paper presents a dual focus, investigating the behavior of nanosecond repetitively pulsed discharges (NRPDs) at elevated gas densities and characterizing the associated hydrodynamic effects. The study delves into the dynamics of NRPDs under varied conditions, shedding light on their behavior in environments with increased gas density. Additionally, the hydrodynamic effects of NRPDs are thoroughly examined, providing valuable insights into their impact on the surrounding flow dynamics.
Anchoring of premixed jet flames in vitiated crossflow with pulsed nanosecond spark discharge
S. A. Shcherbanev, T. Morinière, R. Solana-Pérez, M. Weilenmann, Y. Xiong, U. Doll, N. Noiray
Applications in Energy and Combustion Science, 1, 100010.
The paper presents experimental findings on the impact of nanosecond repetitively pulsed discharge (NRPD) on flame stabilization and anchoring in a premixed jet within a hot vitiated crossflow. Through direct imaging and emission spectroscopy, the study reveals NRPD's ability to robustly anchor flames, influencing lift-off distance and enhancing OH radical production. This understanding is crucial for improving combustion efficiency, predicting NOx emissions, and designing cooling technologies. The study positions NRPD as a promising technology for real engine applications, offering insights into its effectiveness under various conditions, contributing to advancements in flame stabilization.