Flow, Turbulence and Combustion最新文献

{"title":"Advances in Computational Combustion: The UK Consortium on Turbulent Reacting Flows","authors":"Nilanjan Chakraborty, Nedunchezian Swaminathan, Salvador Navarro-Martinez","doi":"10.1007/s10494-023-00479-2","DOIUrl":"10.1007/s10494-023-00479-2","url":null,"abstract":"","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"767 - 768"},"PeriodicalIF":2.4,"publicationDate":"2023-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183960","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Investigation of Combustion Instabilities in Swirling Flames with Hydrogen Enrichment","authors":"Yu Gong,&nbsp;Daniel Fredrich,&nbsp;Andrew J. Marquis,&nbsp;William P. Jones","doi":"10.1007/s10494-023-00476-5","DOIUrl":"10.1007/s10494-023-00476-5","url":null,"abstract":"<div><p>This work presents a numerical study on technically premixed, swirl-stabilised flames in the PRECCINSTA model combustor. The employed method, BOFFIN-LES, comprises a fully compressible formulation to study unsteady combustion with thermo-acoustic instabilities. To allow for this, the iso-thermal flows are first investigated, based on which three reacting cases are established. The investigation delves into various aspects including flame topology, flow characteristics, and the related thermo-acoustic and hydrodynamic instabilities are studied and results are benchmarked against available measurement data. The dominant feedback mechanism of the observed thermo-acoustic fluctuations is identified; the evolution of the helical vortex is discussed together with the related flame stabilisation process. Furthermore, the interplay of the thermo-acoustic oscillations, helical structure, and the flame stabilisation process is summarised in the end, with the potential effect of the wall-heat transfer on them discussed. This work establishes that the Large Eddy Simulation (LES) effectively captures the iso-thermal flow dynamics and the flame topology under various operating conditions, with a good prediction of the thermo-acoustic frequencies in all the cases. The dominant driving mechanism of the observed thermo-acoustic fluctuations was identified as a combined effect of equivalence ratio and velocity fluctuations in all the cases investigated. The effect of Hydrogen enrichment on modifying the flame topology and changing the thermo-acoustic instability features are well predicted by the simulations. Moreover, different modes of the helical vortex are detected, and their periodic excitement, evolution, and effect on flame stabilisation are discussed in great detail. To conclude, this LES-based investigation offers valuable insights into the complex interplay of unsteady combustion, acoustic fluctuations, flow dynamics, and solid boundaries within swirling flames subjected to unsteady conditions.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"953 - 993"},"PeriodicalIF":2.4,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00476-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183897","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large Eddy Simulation of Turbulent Flame Synthesis of Silica Nanoparticles with an Extended Population Balance Model","authors":"Malamas Tsagkaridis,&nbsp;George Papadakis,&nbsp;William P. Jones,&nbsp;Stelios Rigopoulos","doi":"10.1007/s10494-023-00470-x","DOIUrl":"10.1007/s10494-023-00470-x","url":null,"abstract":"<div><p>In the present study, a recently proposed extended population balance equation (PBE) model for aggregation and sintering is incorporated into a large eddy simulation-probability density function (LES-PDF) modelling framework to investigate synthesis of silica nanoparticles in a turbulent diffusion flame. The stochastic field method is employed to solve the LES-PBE-PDF equations, characterising the influence of the unresolved sub-grid scale motions and accounting for the interactions between turbulence, chemistry and particle dynamics. The models for gas-phase chemistry and aerosol dynamics are the same as those recently used by the authors to simulate silica synthesis in a laminar flame (Tsagkaridis et al. in Aerosol Sci Technol 57(4):296–317, 2023). Thus, by retaining the same kinetics without any adjustments in parameters, we focus on the modelling issues arising in silica flame synthesis. The LES results are compared with experimental in-situ small-angle X-ray scattering (SAXS) data from the literature. Good agreement is found between numerical predictions and experimental data for temperature. However, the LES model underestimates the SAXS data for the primary particle diameter by a factor of two. Possible reasons for this discrepancy are discussed in view of the previous laminar flame simulations.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"1029 - 1057"},"PeriodicalIF":2.4,"publicationDate":"2023-08-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00470-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183618","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Scaling of Flame Describing Functions in Premixed Swirling Flames","authors":"Dimitrios P. Kallifronas,&nbsp;Pervez Ahmed,&nbsp;James C. Massey,&nbsp;Midhat Talibi,&nbsp;Andrea Ducci,&nbsp;Ramanarayanan Balachandran,&nbsp;Nedunchezhian Swaminathan","doi":"10.1007/s10494-023-00458-7","DOIUrl":"10.1007/s10494-023-00458-7","url":null,"abstract":"<div><p>Predicting the response of swirling flames subjected to acoustic perturbations poses significant challenges due to the complex nature of the flow. In this work, the effect of swirl number on the Flame Describing Function (FDF) is explored through a computational study of four bluff-body stabilised premixed flames with swirl numbers ranging between 0.44 and 0.97 and at forcing amplitudes of 7% and 25% of the mean bulk velocity. The LES model used for the simulations is validated by comparing two of those flames to experiments. The comparison is observed to be good with the computations capturing the unforced flow structure, flame height and FDF behaviour. It is found that changes in the swirl number can affect the location of the minima and maxima of the FDF gain in the frequency space. These locations are not affected by changes in the forcing amplitude, but the gain difference between the minima and the maxima is reduced as the forcing amplitude is increased. It is then attempted to scale the FDF using Strouhal numbers based on two different flame length scales. A length scale based on the axial height of the maximum heat release rate per unit length leads to a good collapse of the FDF gain curves. However, it is also observed that flow instabilities present in the flow can affect the FDF scaling leading to an imperfect collapse.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"929 - 951"},"PeriodicalIF":2.4,"publicationDate":"2023-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00458-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183838","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modification of the SSG/LRR-Omega Model for Turbulent Boundary Layer Flows in an Adverse Pressure Gradient","authors":"Tobias Knopp,&nbsp;Nico Reuther,&nbsp;Matteo Novara,&nbsp;Daniel Schanz,&nbsp;Erich Schülein,&nbsp;Andreas Schröder,&nbsp;Christian J. Kähler","doi":"10.1007/s10494-023-00457-8","DOIUrl":"10.1007/s10494-023-00457-8","url":null,"abstract":"<div><p>A modification of the RANS turbulence model SSG/LRR-<span>(omega )</span> for turbulent boundary layers in an adverse pressure gradient is presented. The modification is based on a wall law for the mean velocity, in which the log law is progressively eroded in an adverse pressure gradient and an extended wall law (designated loosely as a half-power law) emerges above the log law. An augmentation term for the half-power law region is derived from the analysis of the boundary-layer equation for the specific rate of dissipation <span>(omega )</span>. An extended data structure within the RANS solver provides, for each viscous wall point, the field points on a wall-normal line. This enables the evaluation of characteristic boundary layer parameters for the local activation of the augmentation term. The modification is calibrated using a joint DLR/UniBw turbulent boundary layer experiment. The modified model yields an improved predictive accuracy for flow separation. Finally, the applicability of the modified model to a 3D wing-body configuration is demonstrated.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 2","pages":"409 - 438"},"PeriodicalIF":2.4,"publicationDate":"2023-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00457-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"5162786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling Gas Flows in Packed Beds with the Lattice Boltzmann Method: Validation Against Experiments","authors":"Tanya Neeraj,&nbsp;Christin Velten,&nbsp;Gabor Janiga,&nbsp;Katharina Zähringer,&nbsp;Reza Namdar,&nbsp;Fathollah Varnik,&nbsp;Dominique Thévenin,&nbsp;Seyed Ali Hosseini","doi":"10.1007/s10494-023-00444-z","DOIUrl":"10.1007/s10494-023-00444-z","url":null,"abstract":"<div><p>This study aims to validate the lattice Boltzmann method and assess its ability to accurately describe the behavior of gaseous flows in packed beds. To that end, simulations of a model packed bed reactor, corresponding to an experimental bench, are conducted, and the results are directly compared with experimental data obtained by particle image velocimetry measurements. It is found that the lattice Boltzmann solver exhibits very good agreement with experimental measurements. Then, the numerical solver is further used to analyze the effect of the number of packing layers on the flow structure and to determine the minimum bed height above which the changes in flow structure become insignificant. Finally, flow fluctuations in time are discussed. The findings of this study provide valuable insights into the behavior of the gas flow in packed bed reactors, opening the door for further investigations involving additionally chemical reactions, as found in many practical applications.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 2","pages":"463 - 491"},"PeriodicalIF":2.4,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00444-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4538697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Numerical Study on Premixed Turbulent Planar Ammonia/Air and Ammonia/Hydrogen/Air Flames: An Analysis on Flame Displacement Speed and Burning Velocity","authors":"Parsa Tamadonfar,&nbsp;Shervin Karimkashi,&nbsp;Ossi Kaario,&nbsp;Ville Vuorinen","doi":"10.1007/s10494-023-00445-y","DOIUrl":"10.1007/s10494-023-00445-y","url":null,"abstract":"<div><p>The economic storage and transportation of ammonia (<span>(hbox {NH}_3)</span>), and its capability to be thermally decomposed to hydrogen (<span>(hbox {H}_2)</span>) make it a potential carbon-free synthetic fuel for the future. To comprehend the fundamental characteristics of <span>(hbox {NH}_3)</span> as a primary fuel enriched with <span>(hbox {H}_2)</span> under low turbulent premixed flame conditions, three quasi direct numerical simulations (quasi-DNS) with detailed chemistry and the mixture-averaged transport model are conducted under decaying turbulence herein. The Karlovitz number is fixed to 4.28 for all the test conditions. The blending ratio (<span>(alpha)</span>), specifying the hydrogen concentration in the ammonia/hydrogen mixture, varies from 0.0 to 0.6. The results reveal that the mean value of the density-weighted flame displacement speed (<span>(S_{textrm{d}}^{*})</span>) is similar to (higher than) the unstrained premixed laminar burning velocity (<span>(S_{textrm{L}}^{0})</span>) for <span>(hbox {NH}_3/)</span>air flame (<span>(hbox {NH}_3/hbox {H}_2/)</span>air flames). Furthermore, the performance of two extrapolation relations for estimating <span>(S_{textrm{d}}^{*})</span> as linear and non-linear functions of flame front curvature is discussed thoroughly. The performances of both models are almost similar when evaluating the data near the leading edge of the flame. However, the non-linear one offers more accurate results near the trailing edge of the flame. The results show that the mean flame stretch factor increases with increasing the blending ratio, suggesting that the mean flamelet consumption velocity deviates from <span>(S_{textrm{L}}^{0})</span> by enriching the mixture with <span>(hbox {H}_2)</span>. The mean value of the local equivalence ratio (<span>(phi)</span>) for the turbulent <span>(hbox {NH}_3/)</span>air flame is almost equal to its laminar counterpart, while it deviates significantly for <span>(hbox {NH}_3/hbox {H}_2/)</span>air flames. In addition, the local equivalence ratio for the flame front with positive curvature values is higher than the negatively curved regions for <span>(hbox {NH}_3/hbox {H}_2/)</span>air flames due to <span>(hbox {H}_2)</span> preferential diffusion. Furthermore, the results indicate that hydrogen is consumed faster in positively curved regions compared to the negatively curved zones due to enhanced reaction rates of specific chemical reactions.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 2","pages":"717 - 741"},"PeriodicalIF":2.4,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00445-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4421788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Period-2 Thermoacoustics in a Swirl-Stabilised Partially Premixed Flame Computed Using Large Eddy Simulation","authors":"Ankit D. Kumar,&nbsp;James C. Massey,&nbsp;Michael Stöhr,&nbsp;Wolfgang Meier,&nbsp;Nedunchezhian Swaminathan","doi":"10.1007/s10494-023-00452-z","DOIUrl":"10.1007/s10494-023-00452-z","url":null,"abstract":"<div><p>A partially premixed swirl-stabilised flame under thermoacoustically unstable conditions is studied using large eddy simulation with an unstrained flamelet model for the filtered reaction rate. The simulation results agree well with measured statistics of velocity, temperature and mixture fraction. Two thermoacoustic modes at approximately 300 and 590 Hz are excited for the case studied. The second mode pressure amplitude is comparable to that of the first mode. However, the second mode of heat release rate fluctuations is not as significant as for the pressure which results in a 2:1 frequency locking behaviour. The analysis offers insights into the physical mechanism involved in the excitation of the two modes and the 2:1 frequency locking behaviour. The index based on the Rayleigh Criterion in frequency domain is analysed to understand the coupling between the heat release rate and pressure fluctuations. It is observed that there is a nonlinear interaction between the two modes resulting in energy exchange across the two modes. The conventional Rayleigh Index has limitations in explaining the observed dynamics and therefore, a modified Rayleigh Index is defined to understand the effects of nonlinear mode interactions on thermoacoustic characteristics. A mode shape analysis using LES and acoustic-modelling reveals that the first mode may be a Helmholtz mode with internal damping that is excited by an acoustic source, and the second mode has the characteristic shape of a chamber mode.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"995 - 1028"},"PeriodicalIF":2.4,"publicationDate":"2023-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00452-z.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Numerical Study of Aero Engine Sub-idle Operation: From a Realistic Representation of Spray Injection to Detailed Chemistry LES-CMC","authors":"Max Okraschevski,&nbsp;Léo C. C. Mesquita,&nbsp;Rainer Koch,&nbsp;Epaminondas Mastorakos,&nbsp;Hans-Jörg Bauer","doi":"10.1007/s10494-023-00443-0","DOIUrl":"10.1007/s10494-023-00443-0","url":null,"abstract":"<div><p>High altitude relight is a matter of increasing importance for aero engine manufacturers, in which combustion plays literally a vital role. In this paper we want to evaluate the predictive capability of a combined Smoothed Particle Hydrodynamics (SPH) and Large Eddy Simulation with Conditional Moment Closure (LES-CMC) approach for a spray combustion process at these extreme conditions. The focus is on the SPH modelling of the kerosene primary atomization, the extraction of realistic spray boundary conditions for LES-CMC and the effect of the spray on combustion. Interestingly, it will be demonstrated that the fragment size distributions resulting from the airblast atomization are characterized by bimodal behaviour during the relight process and that small and large fragments differ significantly in their dynamical behavior. This is shown to affect the combustion in the Central Recirculation Zone (CRZ). Very large fragments are even able to supersede the flame from the CRZ, such that endothermic pyrolysis becomes dominant, but simultaneously essential to sustain and stabilize the remaining flame with reactive pyrolysis species. The study proves the ability of our methodology for extreme operating conditions, in which experimental insights are hardly possible.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 2","pages":"493 - 530"},"PeriodicalIF":2.4,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00443-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4257486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Flow Configuration and Thermal Wall Boundary Conditions on Turbulence During Premixed Flame-Wall Interaction within Low Reynolds Number Boundary Layers","authors":"Umair Ahmed,&nbsp;Nilanjan Chakraborty,&nbsp;Markus Klein","doi":"10.1007/s10494-023-00437-y","DOIUrl":"10.1007/s10494-023-00437-y","url":null,"abstract":"<div><p>The influence of flow configuration on flame-wall interaction (FWI) of premixed flames within turbulent boundary layers has been investigated. Direct numerical simulations (DNS) of two different flow configurations for flames interacting with chemically inert isothermal and adiabatic walls in fully developed turbulent boundary layers have been performed. The first configuration is an oblique wall interaction (OWI) of a V-flame in a turbulent channel flow and the second configuration is a head-on interaction (HOI) of a planar flame in a turbulent boundary layer. These simulations are representative of stoichiometric methane-air mixture under atmospheric conditions and the non-reacting turbulence for these simulations corresponds to the friction velocity based Reynolds number of <span>(Re_{tau }=110)</span>. It is found that the mean wall shear stress, mean wall friction velocity and the mean velocity statistics are affected during FWI and the behaviour for these quantities varies under the different flow configurations as well as for the different thermal wall boundary conditions. The behaviour of the quenching distance and mean wall heat flux under isothermal wall conditions is found to be significantly different between the two flow configurations. The variation of the non-dimensional temperature in wall units for cases with isothermal walls suggests that the temperature in the log-layer region is significantly altered by the evolving wall heat flux in both flow configurations. Statistics of the mean Reynolds stresses and turbulence dissipation rate show that the flame significantly alters the behaviour of turbulence due to thermal expansion effects and flow configuration plays an important role.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"111 3","pages":"825 - 866"},"PeriodicalIF":2.4,"publicationDate":"2023-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00437-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"7183899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}