Pub Date : 2023-05-12DOI: 10.1080/13647830.2023.2211537
N. Sekularac, X. Fang, W. Bushe, M. Davy
Data from all spatial locations of nine turbulent flames in the Cambridge/Sandia swirl database are combined to study how the choice of scalar variables in conditional moment closure (CMC) type approaches affect the conditional spatial fluctuations of reactive scalars. In order to investigate the influence of swirl and stratification, two additional data-sets have been constructed. Principal component analysis (PCA) is applied to help identify the number of scalar variables and the most appropriate choices to describe the composition space. Two PCA scaling methods have been adopted, namely Pareto and Auto-scaling. Regardless of the data-set investigated and the scaling method used, the results suggest that a single principal component correlated with temperature accounted for the largest variance. For the first moment hypothesis, four progress variable, c, definitions identified by PCA are selected as conditioning variables to investigate the conditional fluctuations and normalised RMS of various species and temperature from all three databases at all axial locations. The results indicate that two control variables based on mixture fraction, Z, and progress variable significantly reduce the conditional fluctuations of scalars compared to a single variable. The selection of progress variables had minimal effects on the RMS of conditional fluctuations for all tested conditions, although a slight reduction of conditional fluctuations was found for the temperature-based progress variable, which can potentially help the further extension of CMC-based models in different flame configurations. The present study also shows that using Z and c (regardless of its definition) as two conditioning scalars enables the detachment of the thermo-chemical state from space, swirl and stratification effects. This suggests that adopting a doubly conditioned source term estimation (DCSE) approach might successfully predict the considered set of flames, assuming that ensembles are divided along the axial direction.
{"title":"Conditional space evaluation of progress variable definitions for Cambridge/Sandia swirl flames","authors":"N. Sekularac, X. Fang, W. Bushe, M. Davy","doi":"10.1080/13647830.2023.2211537","DOIUrl":"https://doi.org/10.1080/13647830.2023.2211537","url":null,"abstract":"Data from all spatial locations of nine turbulent flames in the Cambridge/Sandia swirl database are combined to study how the choice of scalar variables in conditional moment closure (CMC) type approaches affect the conditional spatial fluctuations of reactive scalars. In order to investigate the influence of swirl and stratification, two additional data-sets have been constructed. Principal component analysis (PCA) is applied to help identify the number of scalar variables and the most appropriate choices to describe the composition space. Two PCA scaling methods have been adopted, namely Pareto and Auto-scaling. Regardless of the data-set investigated and the scaling method used, the results suggest that a single principal component correlated with temperature accounted for the largest variance. For the first moment hypothesis, four progress variable, c, definitions identified by PCA are selected as conditioning variables to investigate the conditional fluctuations and normalised RMS of various species and temperature from all three databases at all axial locations. The results indicate that two control variables based on mixture fraction, Z, and progress variable significantly reduce the conditional fluctuations of scalars compared to a single variable. The selection of progress variables had minimal effects on the RMS of conditional fluctuations for all tested conditions, although a slight reduction of conditional fluctuations was found for the temperature-based progress variable, which can potentially help the further extension of CMC-based models in different flame configurations. The present study also shows that using Z and c (regardless of its definition) as two conditioning scalars enables the detachment of the thermo-chemical state from space, swirl and stratification effects. This suggests that adopting a doubly conditioned source term estimation (DCSE) approach might successfully predict the considered set of flames, assuming that ensembles are divided along the axial direction.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48205184","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}
Pub Date : 2023-05-11DOI: 10.1080/13647830.2023.2209047
Ye Wang, Y. Minamoto, M. Shimura, M. Tanahashi
The quenching mode of local flame–wall interaction (FWI) is investigated for its response to different levels of turbulence intensity as well as its effect on quenching distance, wall heat flux, and near-wall reaction. For that, direct numerical simulations of turbulent premixed methane combustion in a constant volume vessel are carried with initial Karlovitz numbers (Ka) of 1.0, 10.0, and 30.0. Local flame–wall quenching positions are identified based on the local fuel consumption speed during the turbulent combustion process, and the local FWI events have been classified into four quenching modes according to the flame–wall geometric relationships of quenching positions, namely head-on quenching (HOQ), oblique-wall quenching, side-wall quenching (SWQ), and back-on quenching (BOQ). The results show that in the case with higher initial Ka, the flame surface shows a more complicated wrinkled structure due to the flame–turbulence interaction. Meanwhile, the local quenching distance defined based on the identified quenching position is strongly influenced by the near-wall flow, and the range of the local quenching mode extends further to BOQ. However, for all three cases, HOQ and near-HOQ modes account for the majority of local FWI. Wall heat flux and heat release rate (HRR) of near-wall reaction yield high values for the FWI under HOQ or BOQ and are low for SWQ. In addition, there is a discrepancy in the near-wall transportation of some species under different quenching modes, which further leads to the difference in FWI-induced near-wall reaction regarding its total and elementary HRR.
{"title":"Quenching modes of local flame–wall interaction for turbulent premixed methane combustion in a constant volume vessel","authors":"Ye Wang, Y. Minamoto, M. Shimura, M. Tanahashi","doi":"10.1080/13647830.2023.2209047","DOIUrl":"https://doi.org/10.1080/13647830.2023.2209047","url":null,"abstract":"The quenching mode of local flame–wall interaction (FWI) is investigated for its response to different levels of turbulence intensity as well as its effect on quenching distance, wall heat flux, and near-wall reaction. For that, direct numerical simulations of turbulent premixed methane combustion in a constant volume vessel are carried with initial Karlovitz numbers (Ka) of 1.0, 10.0, and 30.0. Local flame–wall quenching positions are identified based on the local fuel consumption speed during the turbulent combustion process, and the local FWI events have been classified into four quenching modes according to the flame–wall geometric relationships of quenching positions, namely head-on quenching (HOQ), oblique-wall quenching, side-wall quenching (SWQ), and back-on quenching (BOQ). The results show that in the case with higher initial Ka, the flame surface shows a more complicated wrinkled structure due to the flame–turbulence interaction. Meanwhile, the local quenching distance defined based on the identified quenching position is strongly influenced by the near-wall flow, and the range of the local quenching mode extends further to BOQ. However, for all three cases, HOQ and near-HOQ modes account for the majority of local FWI. Wall heat flux and heat release rate (HRR) of near-wall reaction yield high values for the FWI under HOQ or BOQ and are low for SWQ. In addition, there is a discrepancy in the near-wall transportation of some species under different quenching modes, which further leads to the difference in FWI-induced near-wall reaction regarding its total and elementary HRR.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44011529","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}
Pub Date : 2023-05-02DOI: 10.1080/13647830.2023.2204065
S. Minaev, E. Dats, K. Shtym
The paper analyzes the hydrodynamic instability of a cylindrical flame stabilized in a converging rotating gas flow simulating the flow in a cyclone combustion chamber. The analysis was carried out within the framework of a two-dimensional model describing the gas flow with radial and tangential supply of combustible gas through the walls of a cylindrical chamber. In the stationary case, the gas flow in combustion products and the combustible mixture is described by the solution for a rotating tornado-shaped vortex. The rotation of the gas creates a centrifugal force, which has a stabilizing effect on the flame perturbations. The dependences of the perturbations growth rate on the wave vector of perturbations, the radial and tangential inlet gas velocities, and other parameters of the problem are obtained. The analytical criterion of neutral stability separating regions of stable flame with respect of any perturbations and flame instability in the plane of radial and tangential velocities is obtained. In the absence of rotation and at the large flame radii, the model converts into the Landau- Darrieus model of flame hydrodynamic instability.
{"title":"Hydrodynamic instability of premixed tubular flame stabilized in stretched rotating flow","authors":"S. Minaev, E. Dats, K. Shtym","doi":"10.1080/13647830.2023.2204065","DOIUrl":"https://doi.org/10.1080/13647830.2023.2204065","url":null,"abstract":"The paper analyzes the hydrodynamic instability of a cylindrical flame stabilized in a converging rotating gas flow simulating the flow in a cyclone combustion chamber. The analysis was carried out within the framework of a two-dimensional model describing the gas flow with radial and tangential supply of combustible gas through the walls of a cylindrical chamber. In the stationary case, the gas flow in combustion products and the combustible mixture is described by the solution for a rotating tornado-shaped vortex. The rotation of the gas creates a centrifugal force, which has a stabilizing effect on the flame perturbations. The dependences of the perturbations growth rate on the wave vector of perturbations, the radial and tangential inlet gas velocities, and other parameters of the problem are obtained. The analytical criterion of neutral stability separating regions of stable flame with respect of any perturbations and flame instability in the plane of radial and tangential velocities is obtained. In the absence of rotation and at the large flame radii, the model converts into the Landau- Darrieus model of flame hydrodynamic instability.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43469313","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}
Pub Date : 2023-04-27DOI: 10.1080/13647830.2023.2206379
I. Bashkirtseva, L. Ryashko
Motivated by important chemical engineering applications, we study probabilistic mechanisms of stochastic effects in a randomly forced model of the continuous stirred tank reactor. The bifurcation analysis of the deterministic model reveals the parameter zone of bistability with coexistence of the equilibrium and oscillatory regimes. It is shown that the boundary between basins of these regimes is moving as the bifurcation parameter changes. We study noise-induced transitions across this boundary leading to the stochastic generation of spiking oscillations and backward effect of the noise-induced suppression of large-amplitude spiking. In the study of these stochastic effects, we use statistics extracted from the direct numerical simulation, and an analytical approach using confidence ellipses method. An important probabilistic phenomenon of coherence resonance is revealed and discussed.
{"title":"How random fluctuations can generate and suppress complex oscillatory regimes in continuous stirred tank reactors","authors":"I. Bashkirtseva, L. Ryashko","doi":"10.1080/13647830.2023.2206379","DOIUrl":"https://doi.org/10.1080/13647830.2023.2206379","url":null,"abstract":"Motivated by important chemical engineering applications, we study probabilistic mechanisms of stochastic effects in a randomly forced model of the continuous stirred tank reactor. The bifurcation analysis of the deterministic model reveals the parameter zone of bistability with coexistence of the equilibrium and oscillatory regimes. It is shown that the boundary between basins of these regimes is moving as the bifurcation parameter changes. We study noise-induced transitions across this boundary leading to the stochastic generation of spiking oscillations and backward effect of the noise-induced suppression of large-amplitude spiking. In the study of these stochastic effects, we use statistics extracted from the direct numerical simulation, and an analytical approach using confidence ellipses method. An important probabilistic phenomenon of coherence resonance is revealed and discussed.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48590811","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}
Pub Date : 2023-04-05DOI: 10.1080/13647830.2023.2197409
Long Zhang, Xingyu Su, Hua Zhou, Z. Ren
Considerable research has been reported on developing effective active control means to suppress oscillating combustion. The typical pressure oscillation can be divided into linear growth, transition and saturation stages. In this study, a sliding mode control strategy, consisting of a state estimate model, disturbance observers and a sliding mode controller, is proposed to suppress the longitudinal oscillating combustion. The control strategy is first tested with a nonlinear 0D state space model as the controlled plant. Results show that the state estimate model combined with the singular spectrum analysis (SSA) method can accurately estimate the system state quantities by grouping the SSA modes according to the frequency difference and calculating mode envelopes. To ensure the estimate accuracy, the number of truncated SSA modes varies according to the oscillation stage. The disturbance observers are designed to improve the robustness of the controller by introducing broadband spectrum disturbance to account for the external noise in the observed values. The sliding mode controller can limit the disturbance amplitude, and effectively suppress the pressure oscillation. A 1D Rijke tube acoustic network is also tested to further validate the controller adaptability. With this controller, the Rijke tube pressure oscillation can be effectively eliminated when control starts at the linear growth, transition, or saturation stages.
{"title":"Sliding mode control for longitudinal oscillating combustion","authors":"Long Zhang, Xingyu Su, Hua Zhou, Z. Ren","doi":"10.1080/13647830.2023.2197409","DOIUrl":"https://doi.org/10.1080/13647830.2023.2197409","url":null,"abstract":"Considerable research has been reported on developing effective active control means to suppress oscillating combustion. The typical pressure oscillation can be divided into linear growth, transition and saturation stages. In this study, a sliding mode control strategy, consisting of a state estimate model, disturbance observers and a sliding mode controller, is proposed to suppress the longitudinal oscillating combustion. The control strategy is first tested with a nonlinear 0D state space model as the controlled plant. Results show that the state estimate model combined with the singular spectrum analysis (SSA) method can accurately estimate the system state quantities by grouping the SSA modes according to the frequency difference and calculating mode envelopes. To ensure the estimate accuracy, the number of truncated SSA modes varies according to the oscillation stage. The disturbance observers are designed to improve the robustness of the controller by introducing broadband spectrum disturbance to account for the external noise in the observed values. The sliding mode controller can limit the disturbance amplitude, and effectively suppress the pressure oscillation. A 1D Rijke tube acoustic network is also tested to further validate the controller adaptability. With this controller, the Rijke tube pressure oscillation can be effectively eliminated when control starts at the linear growth, transition, or saturation stages.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47937817","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}
Pub Date : 2023-04-05DOI: 10.1080/13647830.2023.2195375
Weijie Zhang, Quan Zhou, Jinhua Wang, Zuohua Huang
Two stratified premixed Cambridge/Sandia flames SwB1 and SwB9 are modelled using the Flamelet-Generated Manifold in the context of Large-eddy Simulation. Two kinds of sub-grid closure models are adopted and systematically compared, that is, the Dynamically Thickened Flame (DTF) and the Presumed Probable Density Function (PPDF) models, in order to study the effects of artificial flame front thickening introduced by the DTF on the intermediate minor species prediction. It is found that the two methods lead to similar modelling of velocity, temperature, mixture fraction and major species (e.g. CH , O , CO and H O). However, the intermediate minor species CO and H can be over-predicted using the DTF model compared to the PPDF. A correction method proposed recently by Gruhlke et al. is validated in this work to improve the CO/H predictions of DTF. The corrected CO/H mass fractions are nearly consistent with the results of PPDF. It is examined that the Gruhlke-correction performs better if the wrinkling factor is used directly without modification. Meanwhile, the correction exhibits similar good performance with different level of flame front thickening and mixture stratification. The correction is also addressed to correct the species only in the flame front. The results are significant in high-fidelity simulation of intermediate species using the DTF model.
{"title":"Effects of artificial flame front thickening on intermediate minor species prediction using the LES–FGM method","authors":"Weijie Zhang, Quan Zhou, Jinhua Wang, Zuohua Huang","doi":"10.1080/13647830.2023.2195375","DOIUrl":"https://doi.org/10.1080/13647830.2023.2195375","url":null,"abstract":"Two stratified premixed Cambridge/Sandia flames SwB1 and SwB9 are modelled using the Flamelet-Generated Manifold in the context of Large-eddy Simulation. Two kinds of sub-grid closure models are adopted and systematically compared, that is, the Dynamically Thickened Flame (DTF) and the Presumed Probable Density Function (PPDF) models, in order to study the effects of artificial flame front thickening introduced by the DTF on the intermediate minor species prediction. It is found that the two methods lead to similar modelling of velocity, temperature, mixture fraction and major species (e.g. CH , O , CO and H O). However, the intermediate minor species CO and H can be over-predicted using the DTF model compared to the PPDF. A correction method proposed recently by Gruhlke et al. is validated in this work to improve the CO/H predictions of DTF. The corrected CO/H mass fractions are nearly consistent with the results of PPDF. It is examined that the Gruhlke-correction performs better if the wrinkling factor is used directly without modification. Meanwhile, the correction exhibits similar good performance with different level of flame front thickening and mixture stratification. The correction is also addressed to correct the species only in the flame front. The results are significant in high-fidelity simulation of intermediate species using the DTF model.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44905471","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}
Pub Date : 2023-04-05DOI: 10.1080/13647830.2023.2197408
A. Shaklein, A. Karpov
The flame spread over a non-planar surface of solid fuel has been studied numerically by the coupled model of heat transfer using the proposed approach for the evaluation of burning surface regression. The boundary conditions for the surface regression rate are formulated by the combination of flame spread modes over the vertical and horizontal surfaces resulted from the staircase shape of the burning surface. Numerical results showed a good agreement with the experiment on surface regression profile and mass loss of PMMA solid fuel.
{"title":"On the numerical approach to the prediction of flame spread over non-planar surface of solid combustibles","authors":"A. Shaklein, A. Karpov","doi":"10.1080/13647830.2023.2197408","DOIUrl":"https://doi.org/10.1080/13647830.2023.2197408","url":null,"abstract":"The flame spread over a non-planar surface of solid fuel has been studied numerically by the coupled model of heat transfer using the proposed approach for the evaluation of burning surface regression. The boundary conditions for the surface regression rate are formulated by the combination of flame spread modes over the vertical and horizontal surfaces resulted from the staircase shape of the burning surface. Numerical results showed a good agreement with the experiment on surface regression profile and mass loss of PMMA solid fuel.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43883187","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}
Pub Date : 2023-03-16DOI: 10.1080/13647830.2023.2188259
Shinji Hayashi, Yasuyuki Sakai, Kotaro Tanaka
The pressure rise caused by end-gas auto-ignition in spark-ignited engines is discussed using numerical simulation and theoretical approaches. The main objective of this study is to explain the mechanism by which the end-gas expansion during auto-ignition suppresses the pressure rise in spark-ignited engines, and theoretically to demonstrate using asymptotic analysis that the pressure rise depends on the Damköhler number. A one-dimensional direct numerical simulation (DNS) of end-gas auto-ignition is performed, and the modelling assumptions for it are discussed based on the DNS results. The Damköhler number, defined as the acoustic time scale and the characteristic time scale of the chemical reaction, is introduced in the modelling. The end-gas auto-ignition model is solved numerically, and it is shown that the pressure rise increases with the Damköhler number. Additionally, it is shown that the tendency of the pressure rise is due to the balance between the propagation rate of the expansion wave generated in the end gas and the reaction rate at auto-ignition, which varies with the Damköhler number. To derive the analytical solution of the relationship between the pressure rise and Damköhler number, the end-gas auto-ignition model is simplified based on the numerical results. The simplified model for end-gas auto-ignition is then solved using Newton’s method, and the analytical solution of the pressure rise is derived.
{"title":"A theoretical study on the relationship between pressure rise and the Damköhler number of end-gas auto-ignition in spark-ignited engines","authors":"Shinji Hayashi, Yasuyuki Sakai, Kotaro Tanaka","doi":"10.1080/13647830.2023.2188259","DOIUrl":"https://doi.org/10.1080/13647830.2023.2188259","url":null,"abstract":"The pressure rise caused by end-gas auto-ignition in spark-ignited engines is discussed using numerical simulation and theoretical approaches. The main objective of this study is to explain the mechanism by which the end-gas expansion during auto-ignition suppresses the pressure rise in spark-ignited engines, and theoretically to demonstrate using asymptotic analysis that the pressure rise depends on the Damköhler number. A one-dimensional direct numerical simulation (DNS) of end-gas auto-ignition is performed, and the modelling assumptions for it are discussed based on the DNS results. The Damköhler number, defined as the acoustic time scale and the characteristic time scale of the chemical reaction, is introduced in the modelling. The end-gas auto-ignition model is solved numerically, and it is shown that the pressure rise increases with the Damköhler number. Additionally, it is shown that the tendency of the pressure rise is due to the balance between the propagation rate of the expansion wave generated in the end gas and the reaction rate at auto-ignition, which varies with the Damköhler number. To derive the analytical solution of the relationship between the pressure rise and Damköhler number, the end-gas auto-ignition model is simplified based on the numerical results. The simplified model for end-gas auto-ignition is then solved using Newton’s method, and the analytical solution of the pressure rise is derived.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44865124","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}
Pub Date : 2023-02-22DOI: 10.1080/13647830.2023.2178973
Fekadu Mosisa Wako, G. Pio, E. Salzano
Despite the beneficial impact of biofuels on most regulated pollutants and carbon dioxide emissions, their combustion results in the generation of undesired pollutants, such as acetaldehyde and acetic acid. To better understand the chemistry of these species, detailed chemical kinetic models deriving from two alternative strategies for mechanism generation were developed and validated against available data. The first model represents a semi-lumped mechanism comprising 89 species and 366 reactions, whereas the latter is automatically generated to aggregate elemental steps based on a rate-based algorithm, and it contains 541 species and 27,334 reactions. Under the studied conditions, the two kinetic models fairly predicted ignition delay times and laminar burning velocity data of acetic acid and acetaldehyde. Few discrepancies were observed for ignition delay time at temperatures lower than 1300 K. However, the overall agreement between experimental measurements and numerical estimations allowed for the use of the two kinetic models to unravel the chemistry of the investigated species. Highlights Identification of key primary reactions for acetic acid and acetaldehyde Integration of an existing kinetic mechanism with selected reactions Development of a detailed kinetic mechanism through an automated algorithm Comparison of experimental and numerical data for overall reactivity Analysis of the chemistry of acetic acid and acetaldehyde
{"title":"Modelling of acetaldehyde and acetic acid combustion","authors":"Fekadu Mosisa Wako, G. Pio, E. Salzano","doi":"10.1080/13647830.2023.2178973","DOIUrl":"https://doi.org/10.1080/13647830.2023.2178973","url":null,"abstract":"Despite the beneficial impact of biofuels on most regulated pollutants and carbon dioxide emissions, their combustion results in the generation of undesired pollutants, such as acetaldehyde and acetic acid. To better understand the chemistry of these species, detailed chemical kinetic models deriving from two alternative strategies for mechanism generation were developed and validated against available data. The first model represents a semi-lumped mechanism comprising 89 species and 366 reactions, whereas the latter is automatically generated to aggregate elemental steps based on a rate-based algorithm, and it contains 541 species and 27,334 reactions. Under the studied conditions, the two kinetic models fairly predicted ignition delay times and laminar burning velocity data of acetic acid and acetaldehyde. Few discrepancies were observed for ignition delay time at temperatures lower than 1300 K. However, the overall agreement between experimental measurements and numerical estimations allowed for the use of the two kinetic models to unravel the chemistry of the investigated species. Highlights Identification of key primary reactions for acetic acid and acetaldehyde Integration of an existing kinetic mechanism with selected reactions Development of a detailed kinetic mechanism through an automated algorithm Comparison of experimental and numerical data for overall reactivity Analysis of the chemistry of acetic acid and acetaldehyde","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42987792","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}
Pub Date : 2023-02-22DOI: 10.1080/13647830.2023.2178974
Chen Shenshen, Tao Ruyi, Lu Xinggan, Xue Shao, Jiang Kun
Reducing the calculation cost is of great importance as the demand for interior ballistic calculation is increasing. The key factor of interior ballistic simulation is the quest to develop a more efficient method. In this paper, an efficient two-dimension particle element method (PEM) is proposed to simulate the detailed multidimensional flow of the gas and propellant particle in the chamber. Firstly, several real particles are packed as the particle element to reduce the calculation of the solid phase. In particular, the particle element matrix is established to describe the distribution of particle parameters. Secondly, the particle element boundary is adjusted according to the particle’s movement to reduce the computational cost of grid generation. Besides, the dynamic self-adapting mesh map method is adopted to realise the coupling computation between gas phase and the particle element. The application of a standard virtual gun as a standard benchmark for interior ballistic codes is used to validate the accuracy and reliability with 1.68% error. The particle element model accurately describes the distribution of flow field in the chamber. Compared with the two-fluid method, the PEM significantly improves the computational efficiency by 21.7%. The PEM may be promising for the rapid simulation of two-phase flow in interior ballistic.
{"title":"Efficient two-dimension particle element method of interior ballistic two-phase flow","authors":"Chen Shenshen, Tao Ruyi, Lu Xinggan, Xue Shao, Jiang Kun","doi":"10.1080/13647830.2023.2178974","DOIUrl":"https://doi.org/10.1080/13647830.2023.2178974","url":null,"abstract":"Reducing the calculation cost is of great importance as the demand for interior ballistic calculation is increasing. The key factor of interior ballistic simulation is the quest to develop a more efficient method. In this paper, an efficient two-dimension particle element method (PEM) is proposed to simulate the detailed multidimensional flow of the gas and propellant particle in the chamber. Firstly, several real particles are packed as the particle element to reduce the calculation of the solid phase. In particular, the particle element matrix is established to describe the distribution of particle parameters. Secondly, the particle element boundary is adjusted according to the particle’s movement to reduce the computational cost of grid generation. Besides, the dynamic self-adapting mesh map method is adopted to realise the coupling computation between gas phase and the particle element. The application of a standard virtual gun as a standard benchmark for interior ballistic codes is used to validate the accuracy and reliability with 1.68% error. The particle element model accurately describes the distribution of flow field in the chamber. Compared with the two-fluid method, the PEM significantly improves the computational efficiency by 21.7%. The PEM may be promising for the rapid simulation of two-phase flow in interior ballistic.","PeriodicalId":50665,"journal":{"name":"Combustion Theory and Modelling","volume":null,"pages":null},"PeriodicalIF":1.3,"publicationDate":"2023-02-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41750572","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}
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