A5054124257- Combustion and flame dynamics
- Fluid Dynamics and Turbulent Flows
- Wind and Air Flow Studies
- Advanced Thermodynamics and Statistical Mechanics
- Wind Energy Research and Development
- stochastic dynamics and bifurcation
- Nonlinear Dynamics and Pattern Formation
- Particle accelerators and beam dynamics
- Advanced Thermodynamic Systems and Engines
- Aerodynamics and Acoustics in Jet Flows
- Fluid Dynamics and Vibration Analysis
- Magnetic confinement fusion research
- Meteorological Phenomena and Simulations
- Ecosystem dynamics and resilience
- Combustion and Detonation Processes
- Superconducting Materials and Applications
- Advanced Combustion Engine Technologies
- Electromagnetic Launch and Propulsion Technology
- Probabilistic and Robust Engineering Design
- Model Reduction and Neural Networks
- Complex Systems and Time Series Analysis
- Pulsed Power Technology Applications
- Advanced Control Systems Optimization
- Plasma Diagnostics and Applications
- Chaos control and synchronization
Southern University of Science and Technology
2017-2024
Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou)
2021-2022
Hong Kong University of Science and Technology
2017-2022
University of Hong Kong
2017-2022
Institute for Plasma Research
2011-2021
Sangath
2021
National Institute of Technology Delhi
2020
University of Cambridge
2017
Technische Universität Berlin
2016
Integrated Test Range
2014
The ITER project requires additional heating by two neutral beam injectors, each accelerating to 1 MV a 40 A of negative deuterium ions, deliver the plasma power about 17 MW for one hour. As these requirements have never been experimentally met, it was recognized as necessary setup test facility, PRIMA (Padova Research on Megavolt Accelerator), in Italy, including full-size ion source, SPIDER, and prototype whole injector, MITICA, aiming develop injectors be installed ITER. This realization...
In this paper, we analyze the effects of finite correlation time (noise color) combustion noise on noise-induced coherence and early warning indicators (EWIs) via numerical experimental studies. We consider Rijke tube as a prototypical system model an additive Ornstein–Uhlenbeck process while varying intensity time. numerically investigate corresponding resonance multi-fractal properties pressure fluctuations. Subsequently, experimentally validate results elucidate influence color trends in...
In self-excited combustion systems, the application of open-loop forcing is known to be an effective strategy for controlling periodic thermoacoustic oscillations, but it not whether and under what conditions such a would work on oscillations that are simply periodic. this study, we experimentally examine effect acoustic prototypical system consisting ducted laminar premixed flame oscillating quasiperiodically ergodic $\mathbb{T}^{2}$ torus at two incommensurate natural frequencies, $f_{1}$...
We numerically explore the quenching and amplification of self-excited thermoacoustic oscillations in two nonidentical Rijke tubes interacting via time-delay dissipative coupling. On applying either type coupling separately, we find that presence heater powers can shrink regions amplitude death both oscillators, while producing new weaker oscillator. magnitude grows with power mismatch total input. These effects are also present when types applied simultaneously. This study highlights...
Low-density jets are central to many natural and industrial processes. Under certain conditions, they can develop global oscillations at a limit cycle, behaving as prototypical example of self-excited hydrodynamic oscillator. In this study, we perform system identification low-density jet using measurements its noise-induced dynamics in the unconditionally stable regime, prior both Hopf saddle-node points. We show that approach enable prediction (i) order nonlinearity, (ii) locations types...
Based on recent numerical simulations and field experiments, the mechanism behind wake meandering is increasingly accepted to be through amplification of upstream disturbances owing convectively unstable nature flow. In this paper, we deduce a low-order phenomenological model for far-wake region, which based modified form complex Ginzburg–Landau (CGL) equation flows that are in amplifier regime, i.e. only unstable. The reproduces main qualitative features meandering: (i) its origin via...
We present a framework for performing input-output system identification near Hopf bifurcation using data from only the fixed-point branch, prior to point itself. The models with van der Pol-type equation perturbed by additive noise, and identifies parameters via corresponding Fokker-Planck equation. demonstrate on prototypical thermoacoustic oscillator (a flame-driven Rijke tube) undergoing supercritical bifurcation. find that can accurately predict properties of limit cycle beyond it. This...
We use Navier–Stokes-based linear models for wall-bounded turbulent flows to estimate large-scale fluctuations at different wall-normal locations from their measurements a single location. In these models, we replace the nonlinear term by combination of stochastic forcing and an eddy dissipation term. The plays role in energy production large scales, small scales. Based on results channel flow, find that can with reasonable accuracy only when terms vary wall distance length scale be...
This study explores the dynamics of bypass transition a zero pressure gradient boundary layer transitioning under combined influence an isolated roughness element with pulses free-stream turbulence (FST). We consider hemispherical placed over flat plate, while FST are introduced at inlet, which is in contrast to continuous largely explored literature. For fixed intensity and length scale, series eddy-resolving simulations carried out examine effect varying pulsing frequency FST. The flow...
The development of digital twins for wind farms often involves the use large-eddy simulation (LES) to model atmospheric boundary layers. Existing LES solvers primarily focus on accurately capturing streamwise fluctuations. They, however, overlook less energetic cross-stream fluctuations, which play a crucial role in turbine wake evolution. In this study, we conduct systematic parametric study and incorporate changes an open-source solver. improved solver is able predict all three components...
In low-density axisymmetric jets, the onset of global instability is known to depend on three control parameters, namely jet-to-ambient density ratio $S$ , initial momentum thickness $\unicode[STIX]{x1D703}_{0}$ and Reynolds number $Re$ . For sufficiently low values these jets bifurcate from a steady state (a fixed point) self-excited oscillatory limit cycle) when increases above critical value corresponding Hopf point, $Re_{H}$ literature, this bifurcation often regarded as supercritical....
We experimentally study the hydrodynamic instability of a lean-premixed flame stabilized behind circular cylinder. On reducing equivalence ratio (ϕ) at fixed Reynolds number (ReD), we find that transitions from steady mode to varicose and then sinuous mode. By examining time-resolved CH* chemiluminescence images analyzing how Strouhal scales with ReD, determine is convectively unstable, maintained by amplification disturbances in turbulent base flow, whereas globally unstable as result...
Coherence resonance (CR) is a phenomenon in which the response of stable nonlinear system to external noise exhibits peak coherence at an intermediate amplitude. We report first experimental evidence CR hydrodynamic system, low-density jet capable undergoing both supercritical and subcritical Hopf bifurcations. By applying its unconditionally regime, we find that, for types bifurcation, factor peaks amplitude increases as stability boundary approached. also that autocorrelation function...
In this experimental study, we use a data-driven machine learning framework based on genetic programing (GP) to discover model-free control laws (individuals) for suppressing self-excited thermoacoustic oscillations in prototypical laminar combustor. This GP relies an evolutionary algorithm make decisions natural selection. Starting from initial generation of individuals, rank their performance cost function that accounts the trade-off between state (thermoacoustic amplitude) and input...
In this work, we numerically investigate the dynamics of a prototypical thermoacoustic system, generalized Van der Pol oscillator, in presence additive noise varying color (correlation time) and intensity while system undergoes supercritical subcritical Hopf bifurcation. We specifically influence on trends coherence factor Hurst exponent subthreshold region to assess their reliability as instability precursors. The is found reliable only for correlation times much larger than time scale be...
We derive and numerically validate a low-order oscillator model to capture the stochastic dynamics of prototypical thermoacoustic system (a Rijke tube) undergoing subcritical Hopf bifurcation in presence additive noise. find that on fixed-point branch before bifurcation, is dominated by first duct mode, Fokker–Planck solution for Galerkin mode can adequately predict overall system. also this analytical framework predicts well dominant limit-cycle branch, but underperforms hysteretic bistable...