Bulletin of the Lebedev Physics Institute最新文献

{"title":"Combustion Regimes of Ultralean Methane–Hydrogen/Air Premixed Flames with Dominant Diffusion Transport Process","authors":"A. Demin,&nbsp;S. Mokrin,&nbsp;S. Minaev","doi":"10.3103/S1068335624602619","DOIUrl":"10.3103/S1068335624602619","url":null,"abstract":"<p>The combustion regimes of ultralean premixed methane–hydrogen–air flames were experimentally investigated in the planar channel with counterflow gas supply in the presence of local heat source in stagnant zone. It was shown that at low flow velocities of a lean combustible mixture, almost spherical, ball-like flames are formed near the stagnation zone. With increasing gas velocity and enrichment of the mixture the flame repetitive extinction and ignition regime (FREI regime) was observed. The local gas flow velocity near twin spherical sources of combustion was estimated. The average radius of single ball-like sources of combustion was measured for different mixture contents and inlet mixture velocities. The regime diagram of ball-like flame formation, FREI regime and flammability limit was plotted.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S163 - S169"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145170417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Product Channels of the Reaction of Cyanoacetylene with Methylidyne","authors":"L. I. Krikunova,&nbsp;M. M. Evseev,&nbsp;D. P. Porfiriev,&nbsp;V. N. Azyazov","doi":"10.3103/S1068335625600068","DOIUrl":"10.3103/S1068335625600068","url":null,"abstract":"<p>The results of a quantum-chemical study of the reaction of cyanoacetylene HCCCN with the methylidyne CH are presented. Local extrema on the potential energy surface were found and energetically most favorable reaction pathways were identified. The proposed mechanism predicts the formation of cyclic and acyclic products with predominance of linear molecules.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S222 - S226"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171258","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Addressing Axial Singularities in the Cylindrical Laplacian for Nonaxisymmetric Simulations: An Example of the Graetz Problem in Pipes","authors":"V. N. Kurdyumov","doi":"10.3103/S1068335624602553","DOIUrl":"10.3103/S1068335624602553","url":null,"abstract":"<p>A simple procedure for implementing of a finite-difference method for nonasisymmetric problems in cylindrical coordinates is explored. The treatment of axis singularity is based on an obvious physical assumption about the absence of physical singularity at the axis. The proposed method is applied to a nonaxisymmetric Graetz problem in pipes. The numerical results are compared with the analytical solution in the form of series.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S156 - S162"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171261","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Simulation of Rapid Compression Machine Autoignition Experiments","authors":"Felipe Flores-Carrasco,&nbsp;Rubén Palomeque-Santiago,&nbsp;Robert Schießl,&nbsp;Mariano Rubio-Rubio,&nbsp;Mario Sánchez-Sanz,&nbsp;Eduardo Fernández-Tarrazo","doi":"10.3103/S1068335624602577","DOIUrl":"10.3103/S1068335624602577","url":null,"abstract":"<p>Rapid compression machines are often used to measure the ignition delay time (IDT) of fuel-oxidizer mixtures at relatively low temperatures. To evaluate the performance of a chemical kinetic mechanism in predicting the IDT, the analysis traditionally begins by calculating the volume after the compression stage, assuming a 0-dimensional configuration based on the so-called adiabatic-core hypothesis. According to this theory, there exists an isentropically compressed core region in the gas mixture derived from the measured pressure trace in an inert mixture whose composition remains constant after the compression stage and it is unaffected by heat losses. This approach, neglects the effect of heat release on the specific volume during the first stages of ignition and may differ from that of the inert mixture as result of heat release in the adiabatic core due to chemical reactions. This approach typically predicts IDTs that are shorter than the experimental measurements. In this work, we propose an alternative method for analysis using the experimental nonreactive pressure trace, <span>({{p}_{{{text{in}}}}}(t))</span>. This approach disregards the effect of heat release on pressure during the initial stages of ignition, which increases the specific volume and results in a slight overprediction of ignition delay times. By combining both approaches, we establish upper and lower boundaries for IDTs, providing a framework that facilitates the optimization of chemical mechanisms.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S201 - S212"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermal Radiation Characteristics of a Cylindrical Hybrid Porous-Microchannel Counterflow Burner","authors":"A. D. Moroshkina,&nbsp;A. A. Ponomareva,&nbsp;V. V. Mislavskii,&nbsp;E. V. Sereshchenko,&nbsp;V. V. Gubernov,&nbsp;S. N. Tskhai,&nbsp;V. E. Rogozhnikov","doi":"10.3103/S1068335624602668","DOIUrl":"10.3103/S1068335624602668","url":null,"abstract":"<p>In this work a novel burner configuration is proposed as a hybrid concept of counterflow microchannel and cylindrical porous combustor. The fresh mixture is supplied from the ends of two microchannels aligned along the axis of symmetry with a gap between them, through which the combustion products are exiting. This capillary system is encircled by a porous media made of zirconium grains placed in a quartz tube. Thus, the flow of hot combustion products is reverted and preheats both the porous cylindrical layer and supply tubes. It is found that the heat recuperation allows to steady burn propane–air mixture with variation of the flow rate in an order of magnitude. The heat released from the chemical reaction is effectively converted into the thermal radiation flux, the power and spectral characteristics of which are studied. It is demonstrated that with the use of auxiliary optical system the power density can reach several units of W/cm². The possible applications of the proposed configuration to lasing and thermophotovoltaic applications are discussed.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S183 - S191"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169920","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Study on Combustion of Hydrogen Jet in Supersonic Airflow with Detailed and Skeletal Mechanisms","authors":"G. A. Ashirova,&nbsp;A. O. Beketaeva,&nbsp;A. Zh. Naimanova,&nbsp;V. V. Bykov","doi":"10.3103/S1068335624602620","DOIUrl":"10.3103/S1068335624602620","url":null,"abstract":"<p>Understanding supersonic hydrogen combustion is crucial to design propulsion systems in hypersonic vehicles. The choice of a hydrogen combustion chemical kinetics mechanism requires careful consideration of both accuracy and computational efficiency. The goal of this paper is to study the influence of this choice on the performance of the mechanisms on the problem of transverse hydrogen injection into supersonic flow with subsequent combustion taking place. The skeletal mechanism, including 7 species and 8 chemical reactions only and the detailed Kéromnès mechanism, consisting 9 species and 19 reactions are employed to quantify the effect of chemical reactions. A numerical simulation of this supersonic combustion system is performed by solving the three-dimensional Favre-averaged Navier–Stokes equations coupled with a <span>(k - omega )</span> turbulence model. It is revealed that the basic behavior of the flowfield is mostly identical for the two mechanisms for moderate <span>({{M}_{infty }})</span>. The notable differences are observed in the distribution of the OH mass fraction close to the wall region behind the oblique shock wave in the area of lateral flow, with a 12% increase using the detailed Kéromnès mechanism. It is found that with the growth of the <span>({{M}_{infty }})</span> difference increases between the results of combustion products, derived via the abridged skeletal and detailed chemical reaction mechanisms.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S130 - S143"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171119","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigation of Two-Dimensional Counterflow Laminar Flame Using Generalized Coordinates Based Reaction-Diffusion Manifold Approach","authors":"P. Shrotriya,&nbsp;V. V. Bykov,&nbsp;R. Schießl,&nbsp;C. Yu,&nbsp;U. Maas","doi":"10.3103/S1068335625600147","DOIUrl":"10.3103/S1068335625600147","url":null,"abstract":"<p>In this work, the implementation of a reduced model formulation for studying combustion processes is discussed. The reaction-diffusion manifolds (REDIM) approach is used for the reduced model formulation. In REDIM like other manifolds based reduced methods, instead of solving transport equations for every component of the detailed thermo-kinetic state vector, transport equations are solved only for some reduced coordinates. The remaining components of the detailed thermo-kinetic state vector are then expressed as functions of these reduced coordinates, with their values retrieved from precomputed tables. Unlike other methods, in REDIM, these reduced coordinates are of the form of generalized coordinates, which are the indices of grid points of the manifold stored in the tables. This generalized coordinate based formulation is independent of the choice of parameters used to represent the manifold. The current work investigates two-dimensional (2D) counterflow <span>({text{C}}{{{text{H}}}_{{text{4}}}})</span>/air laminar flames using a generalized coordinate based implementation of reduced calculations performed with 2D REDIM. Comparison of species mass fractions and temperature profiles predicted from reduced calculations show good agreement with detailed calculations.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S170 - S177"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemistry Tabulation: REDIM Based Implementation to Treat Blended Hydrogen–Methane Combustion Systems","authors":"V. Bykov,&nbsp;Sudhi Shashidharan,&nbsp;Ulrich Maas","doi":"10.3103/S1068335625600329","DOIUrl":"10.3103/S1068335625600329","url":null,"abstract":"<p>Treatment of the effect of differential/preferential diffusion within manifolds based model reduction concepts, in particular with blended fuels containing hydrogen, represents a challenging problem. Recently these have gained special attention both from implementation as well as from theoretical standpoints. The problem is difficult for reduced modeling because the diffusion complicates the system solution properties in the state space and requires the description of the diffusion term in reduced variables. The present study uses reaction diffusion manifolds (REDIM) to show the capability of the method to accurately reproduce the effects of differential diffusion. In order to keep the framework simple and demonstrate the problem, a premixed flat flame configuration is considered. Additional focus is made on methane blended with hydrogen combustion systems. This is because complex fuel mixtures having significantly different combustion characteristics represent an attractive system for sustainable combustion. The properties of system solutions of detailed and reduced computations are presented, discussed and compared. In the case of a constant parametrization the effect of different projection strategies are studied and modification to the implementation concept is proposed. The parametrization invariance of the implementation scheme is achieved. It is shown that the accuracy of the physical properties computed in both generalized coordinates as well as a modified constant parametrization projection remains high, as the composition of the system changes due to hydrogen dilution.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S144 - S155"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171260","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Effect of the Exit Boundary Condition on the Acoustics of Premixed Flame Propagation in Channels","authors":"David Rodríguez-Gutiérrez,&nbsp;Raquel Gómez-Miguel,&nbsp;Eduardo Fernández-Tarrazo,&nbsp;Mario Sánchez-Sanz","doi":"10.3103/S1068335624602565","DOIUrl":"10.3103/S1068335624602565","url":null,"abstract":"<p>Thermoacoustic instabilities play a fundamental role on the design and operation of the vast majority of combustion systems. The appearance of thermoacoustic instabilities is often unexpected, and their consequences can be critical. Its highly nonlinear nature, together with the wide range of time and length scales, makes numerical simulations challenging, as high-fidelity results are required for its accurate prediction. Fundamental studies of premixed flames propagating under confinement can be found in the literature, with the extensive use of the truncation of the computational domain with a boundary condition to close the problem. Although acoustic-friendly boundary conditions are available, these approaches overlook the complexity of downstream phenomena. This work questions the accuracy of the decoupling between the flow inside and outside the channel, which is implicitly assumed in these approaches, showing that the results can notably change when accurately solving these overlooked phenomena. For this task, the premixed flame propagation process in a semiopen slender channel is solved. The channel is initially filled with a stagnant fuel air mixture at standard conditions which is locally heated in the vicinity of the open end to mimic a spark-induced ignition. An auto-sustained combustion process starts allowing the flame to propagate from the open end to the closed end of the channel, consuming the reactants. The problem is numerically resolved using two different approaches: the first one truncates the computational domain at the channel exit whereas the second one extends the domain to include the atmosphere surrounding the channel. The latter case found violent oscillations in pressure and heat release rate (secondary thermoacoustic mode) right after ignition, as a consequence of the acoustic perturbations introduced by the sudden ejection of hot gas through the channel opening. In the truncated case, pressure remained constant at the channel entrance and flame oscillations were only observed in the second half of the channel and showed smaller amplitude than when the atmosphere was considered in the calculations. Our study suggests that different flame propagation regimes (symmetric and nonsymmetric flame) can be triggered depending on the boundary conditions used, anticipating the importance of using adequate boundary conditions to accurately predict the onset of thermoacoustic instabilities.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S213 - S221"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145169867","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonlinear Analysis of Outward Propagating Hydrodynamically Unstable Flame at Large Gas Expansion Ratio","authors":"S. S. Minaev,&nbsp;V. V. Gubernov,&nbsp;E. P. Dats","doi":"10.3103/S1068335624602607","DOIUrl":"10.3103/S1068335624602607","url":null,"abstract":"<p>In the context of the large thermal-expansion approximation, we derive an equation describing outward propagating flame under conditions of Darrieus–Landau instability. We show that the second-order theory leads to system of two evolution equations for the flame front perturbations and for the potential of the unburned mixture flow. In the limiting case of long evolution, the system of equations can be reduced to one equation similar to the Sivashinsky equation.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"52 2 supplement","pages":"S178 - S182"},"PeriodicalIF":0.7,"publicationDate":"2025-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145171259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}