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Presumed Joint-PDF Modelling for Turbulent Stratified Flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-22 Mohammadreza Ghadimi, Hassan Atayizadeh, M. Mahdi Salehi
Turbulence–chemistry interaction models such as the conditional moment closure and various flamelet models require a presumed Probability Density Function (PDF) model of the conditioning variables. In turbulent stratified flames, a joint-PDF model for a reaction progress variable and the mixture fraction is required. The joint-PDF is often modelled by two beta functions using the first and second moments
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Study of a Premixed Turbulent Counter-Flow Flame with a Large Eddy Simulation Method Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-21 Y. Gong, W. P. Jones, A. J. Marquis
The turbulent counter-flow flame (TCF) has proven to be a useful benchmark to study turbulence-chemistry interactions, however, the widely observed bulk flow fluctuations and their influence on the flame stability remain unclear. In the present work, premixed TCFs are studied numerically using a Large Eddy Simulation (LES) method. A transported probability density function (pdf) approach is adopted
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A Two-Parameter Corresponding States Method for Calculating the Steady-State Evaporation Rate of C 2 –C 9 n-Alkane Droplets in Air for Elevated Pressures and Temperatures Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-12 Dávid Csemány, Viktor Józsa
Advanced gas turbine and internal combustion engine combustion chambers operate at highly elevated pressures and temperatures. Therefore, spray vaporization analysis cannot be limited to the atmospheric environment since evaporation strongly depends on ambient conditions. Presently, the effect of air pressure and temperature on droplet evaporation rate was investigated by using both a transient and
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A Novel One- and Zero-Dimensional Model for Turbulent Jet Ignition Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-11 Konstantinos Bardis, Panagiotis Kyrtatos, Christophe Barro, Alexey Denisov, Yuri Martin Wright, Kai Herrmann, Konstantinos Boulouchos
Turbulent jet ignition (TJI) is a promising combustion technology for burning highly diluted air-fuel mixtures. Computationally efficient models to assess the effect of the operating conditions and design parameters on the ignition propensity and timing are of paramount importance for the development of combustion systems employing TJI. To this end, a one-dimensional (1-D) jet model, which is based
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Analysis of Near-Wall CO due to Unsteady Flame-Cooling Air Interaction Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-02 Rahul Palulli, Mohsen Talei, Robert L. Gordon
The interaction of a stoichiometric, laminar premixed methane/air flame with a coolant jet is investigated using two-dimensional fully resolved simulations (FRSs). The flame is forced at the inlet with velocity modulation and the coolant is injected from a cooling hole located on the wall at the same temperature as the premixture. FRS cases featuring a combination of blowing ratios, forcing frequencies
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The Effect of Bogie Positions on the Aerodynamic Behavior of a High-Speed Train: An IDDES Study Flow Turbulence Combust. (IF 2.472) Pub Date : 2021-01-02 Jiabin Wang, Guglielmo Minelli, Xiujuan Miao, Jie Zhang, Tiantian Wang, Guangjun Gao, Sinisa Krajnović
In this study, an improved delayed detached-eddy simulation method has been used to investigate the aerodynamic behavior of the CRH2 high-speed trains (HST) with different first and last bogie positions. The results of the numerical simulations have been validated against experimental data obtained from a previous wind tunnel test, a full-scale field test and a reduced-scale moving model test. The
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A Numerical Investigation of the Effects of Fuel Composition on the Minimum Ignition Energy for Homogeneous Biogas-Air Mixtures Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-12-18 Vassilios Papapostolou, Charles Turquand d’Auzay, Nilanjan Chakraborty
The minimum ignition energy (MIE) requirements for ensuring successful thermal runaway and self-sustained flame propagation have been analysed for forced ignition of homogeneous stoichiometric biogas-air mixtures for a wide range of initial turbulence intensities and CO2 dilutions using three-dimensional Direct Numerical Simulations under decaying turbulence. The biogas is represented by a CH4 + CO2
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Validation of an Eulerian Stochastic Fields Solver Coupled with Reaction–Diffusion Manifolds on LES of Methane/Air Non-premixed Flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-12-11 Paola Breda, Chunkan Yu, Ulrich Maas, Michael Pfitzner
The Eulerian stochastic fields (ESF) combustion model can be used in LES in order to evaluate the filtered density function to describe the process of turbulence–chemistry interaction. The method is typically computationally expensive, especially if detailed chemistry mechanisms involving hydrocarbons are used. In this work, expensive computations are avoided by coupling the ESF solver with a reduced
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Fast Flow Field Estimation for Various Applications with A Universally Applicable Machine Learning Concept Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-12-11 Michael Leer, Andreas Kempf
This paper presents an approach for the prediction of incompressible laminar steady flow fields over various geometry types. In conventional approaches of computational fluid dynamics (CFD), flow fields are obtained by solving model equations on computational grids, which is in general computationally expensive. Based on the ability of neural networks to intuitively identify and approximate nonlinear
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Effects of Hydrogen-Enrichment on Flame-Holding of Natural Gas Jet Flames in Crossflow at Elevated Temperature and Pressure Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-12-10 Pankaj Saini, Ianko Chterev, Jhon Pareja, Manfred Aigner, Isaac Boxx
The effect of hydrogen (\(\mathrm {H}_{\mathrm {2}}\)) enrichment on the flame-holding characteristics of two natural gas jet flames in crossflow is investigated here, experimentally. The flame and flowfield measurements are analyzed using simultaneously acquired high-speed (10 kHz) stereoscopic particle image velocimetry, planar laser-induced fluorescence of the hydroxyl radical, and OH* chemiluminescence
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Large-Eddy Simulation Study of Ultra-High Fuel Injection Pressure on Gasoline Sprays Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-12-02 S. Wadekar, A. Yamaguchi, M. Oevermann
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Mean Parameters of an Incompressible Turbulent Boundary Layer on the Wind Tunnel Wall at Very High Reynolds Numbers Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-11-23 Anton Gorbushin, Svetlana Osipova, Vladimir Zametaev
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Direct Numerical Simulations of Turbulent Flow Over Various Riblet Shapes in Minimal-Span Channels Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-11-20 S. Endrikat, D. Modesti, M. MacDonald, R. García-Mayoral, N. Hutchins, D. Chung
Riblets reduce skin-friction drag until their viscous-scaled size becomes large enough for turbulence to approach the wall, leading to the breakdown of drag-reduction. In order to investigate inertial-flow mechanisms that are responsible for the breakdown, we employ the minimal-span channel concept for cost-efficient direct numerical simulation (DNS) of rough-wall flows (MacDonald et al. in J Fluid
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Evaluation of Different Turbulent Combustion Models Based on Tabulated Chemistry Using DNS of Heterogeneous Mixtures Under Multi-injection Diesel Engine-Relevant Conditions Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-11-12 Eleftherios Gorgoraptis, Jean-Baptiste Michel, Stéphane Chevillard, Antonio Pires da Cruz
This paper assesses the accuracy of partially-premixed turbulent combustion models based on the tabulation of chemical kinetics, under multi-injection diesel engine-relevant conditions. For this purpose, 2-D direct numerical simulation (DNS) is carried out. Pockets of gaseous n-heptane are randomly distributed in a turbulent field of a partially burnt n-heptane/air mixture. The burnt gases composition
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Validation Strategy of Reduced-Order Two-Fluid Flow Models Based on a Hierarchy of Direct Numerical Simulations Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-11-09 Pierre Cordesse, Alberto Remigi, Benjamin Duret, Angelo Murrone, Thibaut Ménard, François-Xavier Demoulin, Marc Massot
Whereas direct numerical simulation (DNS) have reached a high level of description in the field of atomization processes, they are not yet able to cope with industrial needs since they lack resolution and are too costly. Predictive simulations relying on reduced order modeling have become mandatory for applications ranging from cryotechnic to aeronautic combustion chamber liquid injection. Two-fluid
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Identification of Flame Regimes in Partially Premixed Combustion from a Quasi-DNS Dataset Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-10-29 Thorsten Zirwes, Feichi Zhang, Peter Habisreuther, Maximilian Hansinger, Henning Bockhorn, Michael Pfitzner, Dimosthenis Trimis
Identifying combustion regimes in terms of premixed and non-premixed characteristics is an important task for understanding combustion phenomena and the structure of flames. A quasi-DNS database of the compositionally inhomogeneous partially premixed Sydney/Sandia flame in configuration FJ-5GP-Lr75-57 is used to directly compare different types of flame regime markers from literature. In the simulation
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Numerical Simulations and Experiments of Ignition of Solid Particles in a Laminar Burner: Effects of Slip Velocity and Particle Swelling Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-10-26 Antonio Attili, Pooria Farmand, Christoph Schumann, Sima Farazi, Benjamin Böhm, Tao Li, Christopher Geschwindner, Jan Köser, Andreas Dreizler, Heinz Pitsch
Ignition and combustion of pulverized solid fuel is investigated in a laminar burner. The two-dimensional OH radical field is measured in the experiments, providing information on the first onset of ignition and a detailed characterization of the flame structure for the single particle. In addition, particle velocity and diameter are tracked in time in the experiments. Simulations are carried out with
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A-Priori Validation of Scalar Dissipation Rate Models for Turbulent Non-Premixed Flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-10-14 M. P. Sitte, C. Turquand d’Auzay, A. Giusti, E. Mastorakos, N. Chakraborty
The modelling of scalar dissipation rate in conditional methods for large-eddy simulations is investigated based on a priori direct numerical simulation analysis using a dataset representing an igniting non-premixed planar jet flame. The main objective is to provide a comprehensive assessment of models typically used for large-eddy simulations of non-premixed turbulent flames with the Conditional Moment
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Numerical Investigation of Remote Ignition in Shock Tubes Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-10-03 Jonathan Timo Lipkowicz, Damien Nativel, Sean Cooper, Irenäus Wlokas, Mustapha Fikri, Eric Petersen, Christof Schulz, Andreas Markus Kempf
Highly resolved two- and three-dimensional computational fluid dynamics (CFD) simulations are presented for shock-tube experiments containing hydrogen/oxygen (H2/O2) mixtures, to investigate mechanisms leading to remote ignition. The results of the reactive cases are compared against experimental results from Meyer and Oppenheim (Proc Combust Inst 13(1): 1153–1164, 1971. https://doi.org/10.1016/s0
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Effects of Localized Micro-blowing on a Spatially Developing Flat Turbulent Boundary Layer Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-10-01 Lan Xie, Yao Zheng, Yang Zhang, Zhi-xian Ye, Jian-feng Zou
Direct numerical simulation (DNS) is used to investigate the turbulent flat-plate boundary layer with localized micro-blowing. The 32 × 32 array of micro-holes is arranged in a staggered pattern on the solid wall, located in the developed turbulent region. The porosity of the porous wall is 23%, and the blowing fraction is 0.0015. The Reynolds number based on the inflow velocity is set to be 50,000
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Effects of Differential Diffusion on the Stabilization of Unsteady Lean Premixed Flames Behind a Bluff-Body Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-29 Yu Jeong Kim, Bok Jik Lee, Hong G. Im
Two-dimensional direct numerical simulations were conducted to investigate the effects of differential diffusion on flame stabilization and blow-off dynamics of lean premixed hydrogen–air and syngas–air flames stabilized on a meso-scale bluff-body in a square channel. The unity Lewis number for all species was imposed to isolate the effects of differential diffusion. Four sets of simulation cases were
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Velocity Characteristics of a Round Offset Jet with Different Offset Ratios in a Counterflow Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-21 ZhiWei Li, Yang Xiao, WenXin Huai, LingFeng Ding
A jet entering a counterflow improves the dilution of contaminant discharged from a chemical factory through pipe. The velocity ratio of jet-to-counterflow and the offset distance of the jet from the boundary significantly affect the dilution efficiency of sewage. A free and an offset round jet, in a counterflow, with ranges of jet-to-counterflow velocity ratios and offset ratios, were experimentally
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Towards a dTDLAS-Based Spectrometer for Absolute HCl Measurements in Combustion Flue Gases and a Better Evaluation of Thermal Boundary Layer Effects Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-20 Zhechao Qu, Javis Nwaboh, Olav Werhahn, Volker Ebert
This work presents a mid-IR direct tunable diode laser absorption spectroscopy (dTDLAS)-based HCl spectrometer, which is specially designed and optimized to measure HCl concentration in combustion exhaust gas matrices (i.e. elevated gas temperatures, high water vapour and CO2 contents). The work is motivated by (legal) requirements for monitoring combustion emissions from large-scale power stations
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Simulation of the Self-Ignition of a Cold Premixed Ethylene-Air Jet in Hot Vitiated Crossflow Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-15 Roberto Solana-Pérez, Oliver Schulz, Nicolas Noiray
The aim of this paper is to analyze the self-ignition of a jet flame in hot vitiated cross flow using Large Eddy Simulation with analytically reduced chemistry. A rich premixed ethylene-air mixture (\(\phi = 1.2\)) at 300 K is injected into a hot vitiated crossflow at 1500 K. The simulated reacting flow steady-state was validated against experiments in previous publications and the focus of the present
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Numerical Study of Quenching Distances for Side-Wall Quenching Using Detailed Diffusion and Chemistry Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-08 Thorsten Zirwes, Thomas Häber, Feichi Zhang, Hidemasa Kosaka, Andreas Dreizler, Matthias Steinhausen, Christian Hasse, Alessandro Stagni, Dimosthenis Trimis, Rainer Suntz, Henning Bockhorn
The numerical investigation of quenching distances in laminar flows is mainly concerned with two setups: head-on quenching (HOQ) and side-wall quenching (SWQ). While most of the numerical work has been conducted for HOQ with good agreement between simulation and experiment, far less analysis has been done for SWQ. Most of the SWQ simulations used simplified diffusion models or reduced chemistry and
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DNS of Instantaneous Behavior in Turbulent Forced and Mixed Convection of Liquid Metal Past a Backward-Facing Step Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-09-01 Chaozheng Wang, Pinghui Zhao, Mingzhun Lei, Kun Lu, Zhihao Ge, Jiaming Liu, Yuanjie Li, Gang Pei
A direct numerical simulation has been performed to study instantaneous behavior in lead-bismuth eutectic flows past a vertical, backward-facing step. A turbulent forced convection case and two cases of mixed convection, the first buoyancy-aided flow at a Richardson number Ri of 0.1 and the second buoyancy-opposed flow at \(Ri=0.02\), are simulated and discussed. The Reynolds number based on the bulk
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Why Soot is not Alike Soot: A Molecular/Nanostructural Approach to Low Temperature Soot Oxidation Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-29 Fabian Hagen, Fabian Hardock, Sergej Koch, Nadia Sebbar, Henning Bockhorn, Alexandra Loukou, Heiko Kubach, Rainer Suntz, Dimosthenis Trimis, Thomas Koch
Due to worldwide increasingly sharpened emission regulations, the development of Gasoline Direct Injection and Diesel Direct Injection engines not only aims at the reduction of the emission of nitrogen oxides but also at the reduction of particulate emissions. Regarding present regulations, both tasks can be achieved solely with the help of exhaust after treatment systems. For the reduction of the
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Correction to: Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-28 Elias Sundström, Mehmet N. Tomac
The article Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator written by Elias Sundstrom and Mehmet N. Tomac, was originally published online on 28th June 2020 with Open Access under a Creative Commons Attribution (CC BY) license 4.0.
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Quantitative Flow Visualization of Slightly Underexpanded Microjets by Mach–Zehnder Interferometers Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-26 Sotaro Sugawara, Shinichiro Nakao, Yoshiaki Miyazato, Yojiro Ishino, Kenji Miki
The Mach–Zehnder interferometer with the finite fringe setting is applied for a shock-containing microjet issued from an axisymmetric convergent nozzle with an inner diameter of 1.0 mm at the exit. Experiments are performed at a nozzle pressure ratio of 3.0 to produce a slightly underexpanded sonic jet where the Reynolds number, based upon the diameter and flow properties at the nozzle exit, is \(4
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Effects of Biogas Composition on the Edge Flame Propagation in Igniting Turbulent Mixing Layers Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-25 C. Turquand d’Auzay, V. Papapostolou, N. Chakraborty
Three-dimensional compressible Direct Numerical Simulations have been used to investigate the localised forced ignition of statistically planar biogas/air mixing layers for different levels of turbulence intensity and biogas composition. The biogas is represented by a \(\hbox {CH}_4\)/\(\hbox {CO}_2\) mixture and a two-step mechanism capturing the variation of the unstrained laminar flame speed with
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Assessing Stretched-Vortex Subgrid-Scale Models in Finite Volume Methods for Unbounded Turbulent Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-25 Sean Walters, Xinfeng Gao, Hans Johansen, Stephen Guzik
Simulations of complex, compressible, high-Reynolds-number flows require high-fidelity physics and turbulence models to be appropriately coupled with strong numerical regularization methods. Obtaining grid-independent and scheme-independent solutions of these flows when using both explicit turbulence models and additional numerical regularization is especially important for further testing and development
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Numerical Simulations of Turbulent Flame Propagation in a Fan-Stirred Combustion Bomb and Bunsen-Burner at Elevated Pressure Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-20 Feichi Zhang, Thorsten Zirwes, Peter Habisreuther, Nikolaos Zarzalis, Henning Bockhorn, Dimosthenis Trimis
Large eddy simulations (LES) have been carried out to calculate turbulent flame propagation in a fan-stirred combustion bomb and a Bunsen-type burner. Objective of the work is to reveal the main mechanism of increased flame wrinkling due to elevated pressure and to assess the ability of the turbulent flame-speed closure (TFC-class) combustion model to reproduce the enhancement of flame wrinkling or
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A Wall-Adapted Anisotropic Heat Flux Model for Large Eddy Simulations of Complex Turbulent Thermal Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-14 Florian Ries, Yongxiang Li, Kaushal Nishad, Louis Dressler, Matthias Ziefuss, Amirfarhang Mehdizadeh, Christian Hasse, Amsini Sadiki
In this paper, a wall-adapted anisotropic heat flux model for large eddy simulations of complex engineering applications is proposed. First, the accuracy and physical consistency of the novel heat flux model are testified for turbulent heated channel flows with different fluid properties by comparing with conventional isotropic models. Then, the performance of the model is evaluated in case of more
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Large-Eddy Simulation of a Model Aero-Engine Sooting Flame With a Multiphysics Approach Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-13 Simone Paccati, Davide Bertini, Lorenzo Mazzei, Stefano Puggelli, Antonio Andreini
In this work, an in-house developed multiphysics unsteady approach (U-THERM3D) is employed to compute wall temperatures in a loosely coupled manner for a model aero-engine combustor, fueled with a non-premixed ethylene/air mixture and representative of the RQL technology. Large-Eddy Simulation (LES) is carried out to prove that scale-resolving approaches are required for a reliable prediction of turbulent
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Development and Application of Bivariate 2D-EMD for the Analysis of Instantaneous Flow Structures and Cycle-to-Cycle Variations of In-cylinder Flow Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-10 Mehdi Sadeghi, Karine Truffin, Brian Peterson, Benjamin Böhm, Stéphane Jay
The bivariate two dimensional empirical mode decomposition (Bivariate 2D-EMD) is extended to estimate the turbulent fluctuations and to identify cycle-to-cycle variations (CCV) of in-cylinder flow. The Bivariate 2D-EMD is an adaptive approach that is not restricted by statistical convergence criterion, hence it can be used for analyzing the nonlinear and non-stationary phenomena. The methodology is
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Turbulence–Combustion Interactions in Premixed and Non-premixed Flames Generated by Hot Active Turbulent Jets Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-10 AbdoulAhad Validi, Harold Schock, Farhad Jaberi
Direct numerical simulations of turbulent jet ignition (TJI)-assisted combustion of lean hydrogen–air mixtures are performed in a three-dimensional planar jet configuration for various thermo-chemical conditions. TJI is a novel ignition enhancement method which facilitates the combustion of lean and ultra-lean fuel–air mixtures by rapidly and continuously exposing them to high temperature combustion
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Direct Numerical Simulations of the Evaporation of Dilute Sprays in Turbulent Swirling Jets Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-08 P. P. Ciottoli, F. Battista, R. Malpica Galassi, F. Dalla Barba, F. Picano
The effects of swirled inflows on the evaporation of dilute acetone droplets dispersed in turbulent jets are investigated by means of direct numerical simulation. The numerical framework is based on a hybrid Eulerian–Lagrangian approach and the point-droplet approximation. Phenomenological and statistical analyses of both phases are presented. An enhancement of the droplet vaporization rate with increasing
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An Improved NO Prediction Model for Large Eddy Simulation of Turbulent Combustion Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-07 Jianguo Xu, Dongxin Huang, Ruiyan Chen, Hua Meng
Accurate prediction of nitrogen oxides (NOX) emissions is of great importance in combustion simulations. This work proposes an improved model to predict NO distributions in turbulent flames, based on the large eddy simulation approach and flamelet-progress-variable turbulence combustion model. A separate table for NO reaction rate is constructed to account for both unsteady and nonadiabatic effects
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Combined Blowing/Suction Flow Control on Low-Speed Airfoils Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-01 Vladimir Kornilov
The paper focuses on the application of the blowing/suction technique to control incompressible turbulent boundary layer on 2-D low-speed airfoils. Analysis of the experimental and numerical results obtained with the combined flow control technique through the high-technological perforated sections is carried out. This control method turns out to be a more effective way to improve aerodynamic performance
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Visualization of Valved Pulsejet Combustors and Evidence of Compression Ignition Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-08-01 Vijay Anand, Justas Jodele, Vincent Shaw, Andrew Russell, Erik Prisell, Owe Lyrsell, Ephraim Gutmark
Valved pulsejet combustor geometries of different chamber and tail pipe lengths are tested experimentally. High-speed pressure and ionization data from various opaque engines are complemented with high-speed visualization data (from transparent engines of the same geometric sizing) acquired from three cameras, with the first resolving the broadband luminosity in the device, the second ascertaining
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Ignition Under Strained Conditions: A Comparison Between Instationary Counterflow and Non-premixed Flamelet Solutions Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-30 Z. Sun, C. Hasse, A. Scholtissek
The transient evolution of counterflow diffusion flames can be described in physical space [i.e. by the model of Im et al. (Combust. Sci. Technol. 158:341–363, 2000)], and in composition space through flamelet equations. Both modeling approaches are employed to study the ignition of diluted hydrogen–air, methane–air and DME–air diffusion flames including detailed transport and chemistry modeling. Using
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Modelling Heat Loss Effects in the Large Eddy Simulation of a Lean Swirl-Stabilised Flame Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-20 James C. Massey, Zhi X. Chen, Nedunchezhian Swaminathan
The flame in a gas turbine model combustor close to blow-off is studied using large eddy simulation with the objective of investigating the sensitivity of including different heat loss effects within the modelling. A presumed joint probability density function approach based on the mixture fraction and progress variable with unstrained flamelets is used. The normalised enthalpy is included in the probability
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Dimensional Decomposition of Turbulent Reacting Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-18 Fredrik Grøvdal, Sigurd Sannan, Christoph Meraner, Tian Li, Terese Løvås
A dimensional-decomposition approach, decomposing 3D into 3×1D for turbulent (reacting) flows are motivated, discussed and investigated. In the three-dimensional Linear Eddy Model (LEM3D), three orthogonally intersecting arrays of 1D domains are coupled to capture the 3D characteristics of fluid flows. The currently used recouplings for LEM3D are enlightened and thoroughly discussed. A study of the
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Comparison of Aerodynamic Characteristics of High-Speed Train for Different Configurations of Aerodynamic Braking Plates Installed in Inter-Car Gap Region Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-10 Jiqiang Niu, Yueming Wang, Rui Li, Feng Liu
An improved delayed detached eddy simulation based on a shear–stress transport κ–ω turbulence model is used to investigate the aerodynamic characteristics of a high-speed train with an aerodynamic braking plate installed in the inter-car gap (ICG) region. The flow field and the aerodynamic performance of high-speed trains with different aerodynamic braking plate configurations are compared and analysed
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Determination of Numerical Errors in Under-Resolved DNS of Turbulent Non-isothermal Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-09 S. Yigit, J. Hasslberger, M. Klein
The methodology to quantify the numerical dissipation in Under-resolved DNS (UDNS) based on the balance of the kinetic energy equation by Schranner et al. (Comput Fluids 114:84–97, 2015), has been examined in this study. Furthermore, this methodology has been extended for considering active scalars, based on both balance of the kinetic energy and thermal variance equations for assessing the quality
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Experimental Study of Liquid Spray Mode of Twin Fluid Atomizer Using Optical Diagnostic Tool Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-09 Raju Murugan, Saravanan Balusamy, Pankaj Kolhe
Twin fluid atomizers allow for two different spray forming modes, flow focusing and flow blurring, depending on the operating, geometric, and thermophysical properties of the working liquids. In flow focusing mode, the liquid jet breaks outside the injector, whereas in flow blurring mode, the liquid jet breaks inside the atomizer. Operating conditions are believed to play an essential role in determining
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Acoustic Dampers Effects on the Characteristics of Confined Swirling Partially Premixed Methane Flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-03 Mahmoud M. A. Ahmed, Madjid Birouk
The effects of different baffled configurations of acoustic dampers placed downstream of the dump plane of a combustor on the mean flowfield, coherent structures, acoustics, stability and dynamics of partially premixed methane flames were experimentally investigated. Particle image velocimetry (PIV) was used to capture the instantaneous flowfield downstream of the dump plane or the baffles and proper
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A New Explicit Algebraic Wall Model for LES of Turbulent Flows Under Adverse Pressure Gradient Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-07-01 Sylvia Wilhelm, Jerome Jacob, Pierre Sagaut
A new explicit algebraic wall law for the Large Eddy Simulation of flows with adverse pressure gradient is proposed. This new wall law, referred as adverse pressure gradient power law (APGPL), is developed starting from the power-law of Werner and Wengle (Turbulent Shear Flows, vol 8, Springer, New York, pp 155–168, 1993) in order to mimic an implicit non-equilibrium log-law based on Afzal’s law (Afzal
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Correction to: Effects of Turbulence and Temperature Fluctuations on Knock Development in an Ethanol/Air Mixture Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-30 Minh Bau Luong, Swapnil Desai, Francisco E. Hernández Pérez, Ramanan Sankaran, Bengt Johansson, Hong G. Im
The article ‘Effects of Turbulence and Temperature Fluctuations on Knock Development in an Ethanol/Air Mixture’, written by Minh Bau Luong, Swapnil Desai, Francisco E. Hernández Pérez, Ramanan Sankaran, Bengt Johansson, and Hong G. Im was originally published electronically on the publisher’s internet portal (currently SpringerLink) on 29th May 2020 with open access.
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Mixing Time Scale Models for Multiple Mapping Conditioning with Two Reference Variables Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-29 C. Straub, A. Kronenburg, O. T. Stein, S. Galindo-Lopez, M. J. Cleary
A novel multiple mapping conditioning (MMC) approach has been developed for the modelling of turbulent premixed flames including mixture inhomogeneities due to mixture stratification or mixing with the cold surroundings. MMC requires conditioning of a mixing operator on characteristic quantities (reference variables) to ensure localness of mixing in composition space. Previous MMC used the LES-filtered
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Aeroacoustic Characteristics of a Synchronized Fluidic Oscillator Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-28 Elias Sundström, Mehmet N. Tomac
A new opposite facing oscillator pair is presented where shared feedback channels enable synchronized sweeping of the exiting jets. The design has no moving parts and the oscillator pair is composed in a back-to-back configuration. The synchronized operation generates a near-field acoustic tonality and the objective is to determine the emitted directivity. The acoustic generation mechanisms were determined
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A p -adaptive Matrix-Free Discontinuous Galerkin Method for the Implicit LES of Incompressible Transitional Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-26 F. Bassi; L. Botti; A. Colombo; A. Crivellini; M. Franciolini; A. Ghidoni; G. Noventa
In recent years Computational Fluid Dynamics (CFD) has become a widespread practice in industry. The growing need to simulate off-design conditions, characterized by massively separated flows, strongly promoted research on models and methods to improve the computational efficiency and to bring the practice of Scale Resolving Simulations (SRS), like the Large Eddy Simulation (LES), to an industrial
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Strain Rate Effects on Head-on Quenching of Laminar Premixed Methane-air flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-24 Yujuan Luo, Christina Strassacker, Xu Wen, Zhen Sun, Ulrich Maas, Christian Hasse
Head-on quenching is a canonical configuration for flame-wall interaction. In the present study, the transient process of a laminar premixed flame impinging on a wall is investigated for different strain rates, while previous studies with detailed chemistry and transport focused only on unstrained conditions. Increasing strain rate leads to a reduction in the normalized quenching distance, and an increase
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Evolution of Surface Density Function in an Open Turbulent Jet Spray Flame Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-23 S. P. Malkeson, U. Ahmed, A. L. Pillai, N. Chakraborty, R. Kurose
A three-dimensional Direct Numerical Simulation of an open turbulent jet spray flame representing a laboratory-scale burner configuration has been used to analyse the statistical behaviours of the magnitude of reaction progress variable gradient \(\left| {\nabla c} \right|\) [alternatively known as the Surface Density Function (SDF)] and the strain rates, which affect its evolution. The flame has been
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Evaluation of a Neural Network-Based Closure for the Unresolved Stresses in Turbulent Premixed V-Flames Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-22 Z. M. Nikolaou, C. Chrysostomou, Y. Minamoto, L. Vervisch
Data-driven modelling in fluid mechanics is a promising alternative given the continuous increase of computational power and data-storage capabilities. Highly non-linear flows which include turbulence and reaction are challenging to model, and accurate algebraic closures for the unresolved terms in large eddy simulations of such flows are difficult to obtain. In this study, an artificial neural network
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Impact of Reaction Chamber Geometry on the Particle-Residence-Time in Flame Spray Process Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-20 Lizoel Buss, Dirceu Noriler, Udo Fritsching
Production of functional nanoparticles and nanoscaled powders is a key process in several recent industrial applications. In this work, the flame process in nanoparticle production in sprays is analyzed. Specific focus is on the flow behavior, the temperature distribution, and the residence-time of particles in the hot (reactive) regions in a flame spray reactor that are analyzed by numerical simulations
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Direct Numerical Simulation of Turbulent Spray Combustion in the SpraySyn Burner: Impact of Injector Geometry Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-19 Abouelmagd Abdelsamie, Cheng Chi, Monika Nanjaiah, Ivan Skenderović, Samer Suleiman, Dominique Thévenin
Spray combustion is one of the most important applications connected to modern combustion systems. Direct numerical simulations (DNS) of such multiphase flows are complex and computationally very challenging. Ideally, such simulations account for atomization, breakup, dispersion, evaporation, and finally ignition and combustion; phase change, heat and mass transfer should be considered as well. Considering
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Simulation of a Scramjet Combustor: A Priori Study of Thermochemistry Tabulation Techniques Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-19 J. L. Ruan, L. Bouheraoua, P. Domingo, G. Ribert
Large eddy simulations (LES) of a scramjet combustor are reported in this paper. The case under study is a cavity-based combustion chamber that is experimentally studied at the US Air Force Research Laboratory. The chamber is fed by eleven injectors. The computational domains are either simplified including only one or two injectors or complete with the 11 injectors. A good agreement is found between
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Progress in the Smoothed Particle Hydrodynamics Method to Simulate and Post-process Numerical Simulations of Annular Airblast Atomizers Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-18 G. Chaussonnet, T. Dauch, M. Keller, M. Okraschevski, C. Ates, C. Schwitzke, R. Koch, H.-J. Bauer
This paper illustrates recent progresses in the development of the smoothed particle hydrodynamics (SPH) method to simulate and post-process liquid spray generation. The simulation of a generic annular airblast atomizer is presented, in which a liquid sheet is fragmented by two concentric counter swirling air streams. The accent is put on how the SPH method can bridge the gap between the CAD geometry
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Scalar Gradient and Strain Rate Statistics in Oblique Premixed Flame–Wall Interaction Within Turbulent Channel Flows Flow Turbulence Combust. (IF 2.472) Pub Date : 2020-06-15 Umair Ahmed, Nilanjan Chakraborty, Markus Klein
Three-dimensional direct numerical simulations of V-flames interacting with chemically inert walls in a fully developed turbulent channel flow have been performed under adiabatic and isothermal wall boundary conditions using single-step chemistry. These simulations are representative of stoichiometric methane-air mixture at unity Lewis number under atmospheric conditions. The turbulence in the non-reacting
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