Combustion Theory and Modelling最新文献

{"title":"A laminar smoke point-based soot model considering surface growth and soot reactions","authors":"Shahrooz Motaghian, Tarek Beji","doi":"10.1080/13647830.2023.2267526","DOIUrl":"https://doi.org/10.1080/13647830.2023.2267526","url":null,"abstract":"AbstractThis paper proposes a Laminar Smoke Point (LSP)-based soot model, incorporating (as opposed to previously developed LSP-based models) soot surface growth. The latter is indeed believed to be dominant in soot formation. Simple reactions are also introduced to account for the conversion of fuel and oxygen in soot evolution mechanisms. The proposed and a reference LSP-based soot models have been implemented in OpenFOAM-v2006 and assessed against a wide variety of laminar flames (16 flames). A calibration-evaluation procedure is defined in which some flames are involved in the calibration of the constants, and the majority are utilised in an independent evaluation stage. The results show that the newly added features to the LSP-based soot modelling approach allow for a better agreement over a wider range of conditions, e.g. diluted and highly sooty flames. It is shown that although the proposed model is more accurate for buoyant flames, it performs significantly better than the reference model for non-buoyant flames.Keywords: CFDlaminar smoke pointsoot modellingOpenFOAMlaminar diffusion flames Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThis work is funded by Ghent University (UGent), Belgium. Project number BOF/STA/201909/008.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135142214","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An iterative methodology for REDIM reduced chemistry generation and its validation for partially-premixed combustion","authors":"Prashant Shrotriya, Robert Schießl, Chunkan Yu, Viatcheslav Bykov, Thorsten Zirwes, Ulrich Maas","doi":"10.1080/13647830.2023.2260350","DOIUrl":"https://doi.org/10.1080/13647830.2023.2260350","url":null,"abstract":"AbstractPartially-premixed flames (PPFs) incorporate effects of both premixed and non-premixed types of reaction zones. The modelling of PPFs using manifold-based model reduction methods faces some inherent difficulties due to the underlying assumptions of a-priori identification of the type of combustion system. In this work, the reaction–diffusion manifold (REDIM) model reduction method is applied to study PPFs. The REDIM method requires minimal prior knowledge about the type of combustion system, which makes it a suitable method for studying PPFs. It allows incorporating system-specific diffusion (gradients) terms in a generic way so that the manifold can evolve according to the diffusion related information provided by the combustion system. In this way, a prior identification of the type of combustion system is no longer needed.This work utilises an iterative methodology to generate REDIM chemistry tables so that the reduced manifold can be iteratively converged very close to the detailed manifold according to the gradients of the reduced coordinates provided by the physical combustion system in each iteration step. In addition, a new method is proposed to provide the gradient estimates of the reduced coordinates during the generation of REDIM from the scattered gradient data in REDIM reduced CFD calculations. Laminar triple flames, a special case of PPFs, with two types of mixture fraction gradients are selected as the target cases to assess the presented iterative methodology. REDIM reduced calculations are compared with simulations based on detailed finite-rate kinetics. It is found that in the final iteration steps, temperature and all considered major and minor species mass fraction profiles are very well predicted by the REDIM reduced calculations.Keywords: Reaction–diffusion manifold (REDIM)model reductionpartially-premixed flametriple flamelaminar flame Disclosure statementNo potential conflict of interest was reported by the author(s).Supplemental dataSupplemental data for this article can be accessed online at http://dx.doi.org/10.1080/13647830.2023.2260350.Additional informationFundingFinancial support by the German Research Foundation (DFG) within the projects SFB/TRR 150 (project number 237267381) within sub-projects B06 and B07 is gratefully acknowledged.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135535653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 modeling and parametric analysis of performance of a monopropellant thruster using a single-part catalyst bed model","authors":"Mohammad Reza Salimi, Hadiseh Karimaei, Mostafa Gholampour Yazdi","doi":"10.1080/13647830.2023.2258841","DOIUrl":"https://doi.org/10.1080/13647830.2023.2258841","url":null,"abstract":"AbstractMonopropellant hydrazine thruster, depending on their thrust level, specific impulse, and unique functional regime, are widely used in situation control, orbital transmission, and position correction systems of satellites. In these thrusters, hydrazine decomposes by passing through the catalyst bed in a highly exothermic reaction to hot gas products. Hot gases generate thrust force by passing through a convergent-divergent nozzle. Pore scale analysis of catalytic reactions is very common in various industries and is of interest to researchers due to its accuracy. In this paper, the decomposition chamber of a monopropellant hydrazine thruster is numerically simulated with a single-part bed model at the pore-scale. The length of decomposition chamber was 2.48 cm. Then the effects of parameters such as catalyst granule diameter, catalyst bed porosity coefficient and also chamber inlet pressure on the performance of the decomposition chamber and thruster are investigated. Simulations have been performed for catalyst granules with diameters of 0.88, 1.00 and 1.15 mm in three porosity coefficients of 0.4, 0.55 and 0.65. The inlet pressure is also changed from 10 to 25 bar in four different levels. The results showed that the porosity coefficient is the most effective parameter and with its decrease, the specific impulse and temperature rise, while the thrust force and mass flow rate intensify. Also, the size of the catalyst granules affects the performance of the bed and thruster so that by increasing it (at a certain porosity coefficient), a trend similar to the effect of decreasing the porosity coefficient can be seen in the results. On the other hand, with enhancing inlet pressure, the thrust force increases significantly. In this paper, the effect of bed parameters on the thruster performance is discussed in detail, which contains helpful results for researchers that work on improving the decomposition chamber efficiency.Keywords: monopropellant thruster; catalyst bed; decomposition chamber; catalyst granule diameter; bed porosity coefficient; chamber inlet pressure; pore scale analysis Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"59 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134886474","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 simulation of turbulent premixed flames with the conditional source-term estimation model using Bernstein polynomial expansion","authors":"Mojtaba Latifi, Mohammad Mahdi Salehi","doi":"10.1080/13647830.2023.2261895","DOIUrl":"https://doi.org/10.1080/13647830.2023.2261895","url":null,"abstract":"AbstractConditional Source-term Estimation (CSE) is a turbulence-chemistry interaction model similar to CMC, except that the conditional scalars are calculated from unconditional ones using an integral equation. This problem is inherently ill-posed and should be regularised. Recently, an efficient regularisation approach based on Bernstein polynomial expansion was proposed by Mahdipour and Salehi (Combust. Flame, 2022) in an a priori analysis using DNS data. This work implements this approach in a reacting flow solver, and two laboratory-scale turbulent premixed flames are simulated in the Reynolds-Averaged Navier-Stokes (RANS) context. The turbulent intensity in the first flame is low, and the results show that, unlike the conventional CSE approach, the new approach can accurately predict the flamelet conditional averages. Furthermore, the predicted averaged velocity field and major and minor species mass fractions compare favourably with the experimental measurements. The turbulent intensity in the second flame is relatively higher, and the predicted conditional averages should deviate from an unstrained laminar flame solution. The new approach can correctly predict this trend as well as the flame height in this flame. The computational cost of the new CSE approach is also substantially reduced compared to the regular CSE approach.Keywords: turbulent combustionpremixed flamestabulated chemistryconditional moment closureconditional source-term estimation Disclosure statementNo potential conflict of interest was reported by the author(s).","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135859791","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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 study on three-stage ignition of dimethyl ether by hot air under engine-relevant conditions","authors":"Xinyi Chen, Zisen Li, Yiqing Wang, Wang Han, Arne Scholtissek, Peng Dai, Christian Hasse, Zheng Chen","doi":"10.1080/13647830.2023.2261423","DOIUrl":"https://doi.org/10.1080/13647830.2023.2261423","url":null,"abstract":"AbstractNon-premixed combustion often occurs in practical engines, and it is affected by the coupling effects of chemical kinetics and transport. This study aims to elucidate the individual effect of chemical kinetics, molecular diffusion, and convective transport on non-premixed combustion. To this end, three types of reactive systems are investigated by numerical simulations considering detailed chemistry and transport: (1) thermochemical system: 0D homogeneous autoignition, (2) thermochemical-diffusive system: 1D non-premixed ignition in a static diffusion layer, (3) thermochemical-diffusive-convective system: 1D non-premixed ignition in a counterflow and 2D lifted flame in a coflow. The simulations are carried out for diluted dimethyl ether and hot air under engine-relevant conditions with a pressure of 40 atm and hot air temperatures of 700∼1500 K. First, homogeneous ignition process of DME/air premixture is investigated. It is found that, apart from the low- and high-temperature chemistry which are essential in the typical two-stage ignition, the intermediate-temperature chemistry can also play an important role, especially for slow reaction process in fuel rich regions. Then, the effects of thermochemical conditions and molecular diffusion are assessed for non-premixed ignition process in the 1D diffusion layer. The results show that, the reaction front always initiates from local autoignition in most reactive regions; then it propagates either in sequential auto-ignition mode or in diffusion-driven mode as a deflagration wave. With various thermochemical conditions, the chemical kinetics behave differently and produce complex multibrachial (tetrabrachial, pentabrachial and hexbrachial) structures during the reaction front propagation. Decreasing the diffusion layer thickness generally delays the reaction front initiation but enhances its transition into a diffusion-driven flame. Finally, it is shown that 1D diffusion layer simulations can qualitatively reproduce the complex multibrachial structures in 1D counterflow and 2D coflow at certain conditions. A regime diagram is proposed to separate the effects of chemical kinetics, molecular diffusion, and convective transport.Keywords: non-premixed combustiondimethyl etherthree-stage ignitionintermediate-temperature chemistry Disclosure statementNo potential conflict of interest was reported by the author(s).Supplemental dataSupplemental data for this article can be accessed here https://doi.org/10.1080/13647830.2023.2261423.Additional informationFundingThis work is jointly supported by the National Natural Science Foundation of China (Nos. 52176096 and 51861135309) and the German Research Foundation (DFG, no. 411275182).","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135859159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A super-grid approach for LES combustion closure using the Linear Eddy Model","authors":"Abhilash M. Menon, Michael Oevermann, Alan R. Kerstein","doi":"10.1080/13647830.2023.2260351","DOIUrl":"https://doi.org/10.1080/13647830.2023.2260351","url":null,"abstract":"LES–LEM is a simulation approach for turbulent combustion in which the stochastic Linear Eddy Model (LEM) is used for sub-grid mixing and combustion closure in Large-Eddy Simulation (LES). LEM resolves, along a one-dimensional line, all spatial and temporal scales, provides on-the-fly local turbulent flame statistics, captures finite rate chemistry effects and directly incorporates turbulence-chemistry interaction. However, the approach is computationally expensive as it requires advancing an LEM-line in each LES cell. This paper introduces a novel turbulent combustion closure model for LES using LEM to address this issue. It involves coarse-graining the LES mesh to generate a coarse- level ‘super-grid’ comprised of cell-clusters. Each cell-cluster, instead of each LES cell, then contains a single LEM domain. This domain advances the combined advection–reaction–diffusion solution and also provides suitably conditioned statistics for thermochemical scalars such as species mass fractions. Local LES-filtered thermochemical states are then obtained by probability-density-function (PDF) weighted integration of binned conditionally averaged scalars, akin to standard presumed PDF approaches for reactive LES but with physics-based determination of the full thermochemical state for particular values of the conditioning variables. The proposed method is termed ‘super-grid LEM’ or ‘SG-LEM’. The paper describes LEM reaction–diffusion advancement, the LEM representation of turbulent advection, a novel splicing algorithm (a key feature of LES–LEM) formulated for the super-grid approach, a wall treatment, and a thermochemical LES closure procedure. To validate the proposed model, a pressure-based solver was developed using the OpenFOAM library and tested on a premixed ethylene flame stabilised over a backward facing step, a setup for which some DNS data is available. SG-LEM provides high resolution flame structures, temperature and mass fractions suitable for LES thermochemical closure. Additionally, it provides reaction-rate data at the coarse level, a unique feature compared to other mapping-type closure methods. Quantitative comparisons are made between the proposed model and time-averaged DNS data, focussing on velocity, temperature and species mass fraction. Results show good agreement downstream of the step. Furthermore, comparison with an equivalent Partially-Stirred Reactor (PaSR) simulation demonstrates the superior predictive capability of SG-LEM. Additionally, the paper briefly examines the sensitivity of the model to coarse-graining parameters and finally, explores computational efficiency highlighting the substantial speedup achieved when compared to the standard LES–LEM approach with potentially significant speedup relative to PaSR closure for the intensely turbulent regimes of principal interest.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136309142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diffusive-thermal instabilities of a planar premixed flame aligned with a shear flow","authors":"Joel Daou, Prabakaran Rajamanickam","doi":"10.1080/13647830.2023.2254734","DOIUrl":"https://doi.org/10.1080/13647830.2023.2254734","url":null,"abstract":"The stability of a thick planar premixed flame, propagating steadily in a direction transverse to that of unidirectional shear flow, is studied. A linear stability analysis is carried out in the asymptotic limit of infinitely large activation energy, yielding a dispersion relation. The relation characterises the coupling between Taylor dispersion (or shear-enhanced diffusion) and the flame thermo-diffusive instabilities, in terms of two main parameters, namely, the reactant Lewis number Le and the flow Peclet number Pe. The implications of the dispersion relation are discussed and various flame instabilities are identified and classified in the Le-Pe plane. An important original finding is the demonstration that for values of the Peclet number exceeding a critical value, the classical cellular instability, commonly found for Le<1, exists now for Le>1 but is absent when Le<1. In fact, the cellular instability identified for Le>1 is shown to occur either through a finite-wavelength stationary bifurcation (also known as type-Is) or through a longwave stationary bifurcation (also known as type-IIs). The latter type-IIs bifurcation leads in the weakly nonlinear regime to a Kuramoto-Sivashinsky equation, which is determined. As for the oscillatory instability, usually encountered in the absence of Taylor dispersion in Le>1 mixtures, it is found to be absent if the Peclet number is large enough. The stability findings, which follow from the dispersion relation derived analytically, are complemented and examined numerically for a finite value of the Zeldovich number. The numerical study involves both computations of the eigenvalues of a linear stability boundary-value problem and numerical simulations of the time-dependent governing partial differential equations. The computations are found to be in good qualitative agreement with the analytical predictions.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136309158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"LES of premixed jet flames subjected to extreme turbulence using flamelet-generated manifolds: a comparison of unstrained and strained flamelets","authors":"Weijie Zhang, De-Xu Li, Guangya Hu, Jinhua Wang","doi":"10.1080/13647830.2023.2248960","DOIUrl":"https://doi.org/10.1080/13647830.2023.2248960","url":null,"abstract":"","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45221677","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of ethanol enrichment and engine parameters on the performance of an HCCI engine fuelled with biodiesel/ethanol mixtures","authors":"M. Mosbah, Z. Boutera, Y. Rezgui, M. Guemini, A. Tighezza","doi":"10.1080/13647830.2023.2248954","DOIUrl":"https://doi.org/10.1080/13647830.2023.2248954","url":null,"abstract":"Based on models resulting from the merging of validated kinetic schemes, four reaction mechanisms were developed to describe the combustion of biodiesel-surrogate/ethanol blends in an HCCI engine. The proposed models were then compared to experimental data issued from a modified cooperative fuel research (CFR) engine which can be considered as an HCCI engine. The kinetic scheme displaying the best predictive capabilities, in conjunction with the single-zone HCCI code from the chemkin library, was used to investigate effects of ethanol enrichment and the variation of some important parameters, such as inlet temperature, relative air/fuel ratio and compression ratio, on the combustion and performance characteristics of the investigated HCCI engine. The blended fuels were formed by incrementally adding 10% of ethanol to the neat biodiesel mixture. The inlet temperature ranged from 320 to 420 K with a step of 20 K, whereas air/fuel and compression ratios were varied from 2 to 5 with a step of 0.5, and from 9 to 14 with a step equal to 1, respectively. The obtained data indicated that ethanol effects on the starting of combustion, combustion duration and indicated mean effective pressure were dependent on intake temperature, air/fuel and compression ratios.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47037794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determining the global activation energy of methane–air premixed flames","authors":"A. Moroshkina, Alina A. Ponomareva, V. Mislavskii, E. Sereshchenko, V. Gubernov, V. Bykov, S. Minaev","doi":"10.1080/13647830.2023.2245380","DOIUrl":"https://doi.org/10.1080/13647830.2023.2245380","url":null,"abstract":"In this work, the determination of the apparent activation energy of a global chemical reaction mechanism of the methane–air flames is revisited. The one-step formulation allows to derive the theoretical background for the method to measure the activation energy within the burner stabilised flame setup. The validity of this approach is demonstrated by using the numerical simulations with the detailed reaction model and direct thin filament pyrometry measurements of the temperature distribution in flame. The combination of numerical and experimental approaches allows us to find the activation energy for various mixture compositions. The prediction of numerical simulations and measured values of the activation energy is found to be in good agreement with each other and the data known from the literature. It is demonstrated that two critical phenomena need to be taken into account to obtain a reliable estimate of the activation energy: the flame blow-off and the onset of the diffusive-thermal instabilities. The effect of these critical events on the accuracy of the measurements is discussed as well as prospects of further investigation.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":" ","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48675913","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}