International Journal of Spray and Combustion Dynamics最新文献

{"title":"Direct numerical simulation of SpraySyn burner: Impact of liquid solvent","authors":"A. Abdelsamie, H. Wiggers, F. Kruis, D. Thévenin","doi":"10.1177/17568277231187471","DOIUrl":"https://doi.org/10.1177/17568277231187471","url":null,"abstract":"The SpraySyn burner is a new system recently developed at the University of Duisburg-Essen to investigate experimentally nanoparticle synthesis in spray flames for a variety of materials. The current project aims at performing direct numerical simulations with detailed physicochemical models of configurations closely related to this burner. The effect of using different solvents to produce titanium-dioxide (TiO[Formula: see text]) nanoparticles is discussed in this work. The two solvents considered are o-xylene and ethanol mixed in liquid state with tetraisopropoxide to form TiO[Formula: see text]. The liquid is injected into a pilot flame as dispersed spray with a carrier flow (dispersion gas). The resulting particle size distribution is examined as well. It is in particular observed that using ethanol leads to faster agglomeration and larger nanoparticles. This effect is qualitatively similar to that found when injecting smaller liquid spray droplets.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44736334","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":"Uncertainty quantification analysis of Reynolds-averaged Navier–Stokes simulation of spray swirling jets undergoing vortex breakdown","authors":"Jacopo Liberatori, R. M. Galassi, M. Valorani, P. P. Ciottoli","doi":"10.1177/17568277231183047","DOIUrl":"https://doi.org/10.1177/17568277231183047","url":null,"abstract":"The computational fluid dynamics-based design of next-generation aeronautical combustion chambers is challenging due to many geometrical and operational parameters to be optimized and several sources of uncertainty that arise from numerical modeling. The present work highlights the potential benefits of exploiting Bayesian uncertainty quantification at the preliminary design stage. A prototypical configuration of an acetone/air spray swirling jet is investigated through an Eulerian–Lagrangian method under non-reactive conditions. Two direct numerical simulations (DNSs) provide reference data, coping with different vortex breakdown states. Consequently, a set of Reynolds-averaged Navier–Stokes simulations is conducted. Polynomial chaos expansion (PCE) is adopted to propagate the uncertainty associated with the spray dispersion model and the turbulent Schmidt number, delivering confidence intervals and the sensitivity of the output variance to each uncertain input. Consequently, the most significant sources of modeling uncertainty may be identified and eventually removed via a calibration procedure, thus making it possible to carry out a combustion chamber optimization process that is no longer affected by numerical biases. The uncertainty quantification analysis in the current study demonstrates that the spray dispersion model slightly affects the fuel vapor spatial distribution under vortex breakdown flow conditions, compared with the output variance induced by the selection of the turbulent Schmidt number. As a result, additional high-fidelity experimental and numerical campaigns should exclusively address the development of an ad hoc model characterizing the spatial distribution of the latter in the presence of vortex breakdown phenomenology, discarding any effort to improve the spray dispersion formulation.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-06-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43153272","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":"Flame dynamics of an injection element operated with LOX/H2, LOX/CNG and LOX/LNG in a sub- and supercritical rocket combustor with large optical access","authors":"Jan M. Martin, W. Armbruster, R. Stützer, D. Suslov, J. Hardi, M. Oschwald","doi":"10.1177/17568277231172302","DOIUrl":"https://doi.org/10.1177/17568277231172302","url":null,"abstract":"Hot fire tests were performed using a single-injector research combustor featuring a large optical access window ( 255 × 38  mm) for flame visualisation. Three test campaigns were conducted with the propellant combination of liquid oxygen and hydrogen, liquid oxygen and compressed-natural-gas, as well as liquid oxygen and liquefied-natural-gas at conditions relevant for main- and upper-stage rocket engines. The large optical access enabled synchronised flame imaging using ultraviolet and blue radiation wavelengths covering a large portion of the combustion chamber for various sets of sub- and supercritical operating conditions. Combined with temperature, pressure and unsteady pressure measurements, this data provides a high-quality basis for the validation of numerical modelling. Flame width, length and opening angle as features describing the flame topology were extracted from the imaging. The suitability of flame imaging using ultraviolet and blue radiation wavelengths as qualitative markers of heat release was evaluated. Two-dimensional distributions of the Rayleigh Index were calculated for intervals with and without high-amplitude, self-excited oscillations of the longitudinal acoustic resonance modes. The calculated Rayleigh Index values properly reflect the thermoacoustic state of the chamber, indicating that both types of imaging may be used for qualitative study of thermoacoustic coupling of high-pressure cryogenic flames.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42197297","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":"Distributed heat release effects on entropy generation by premixed, laminar flames","authors":"Akbar Laksana, Parth Patki, T. John, V. Acharya, T. Lieuwen","doi":"10.1177/17568277231172887","DOIUrl":"https://doi.org/10.1177/17568277231172887","url":null,"abstract":"This article studies the generation of entropy disturbances by laminar premixed flames. The total entropy generation equals the integrated ratio of the local heat release rate and the local temperature, namely, ∫ ( q ˙ / T ) d V . Due to this path dependency, evaluating this integral requires an understanding of how the heat release is distributed in the temperature space. Several studies evaluate the local entropy generation as ( ∫ q ˙ d V ) / T b , where T b refers to the burned gas temperature, implicitly assuming all the heat release occurs at T b . Such an approximation is motivated by the high activation energy nature of combustion chemistry. This work evaluates this assumption by comparing it to results from one-dimensional premixed flame calculations for hydrogen, methane, and propane-air flames over a range of pressures, equivalence ratios, and preheat temperatures, quantified via the ratio κ . We show that this assumption is quite reasonable for methane and propane-air flames (with errors ranging from 5% to 25%) but deviates significantly from the exact results for hydrogen flames (where errors can be as high as 50%). In general, the peak heat release moves to lower temperatures as preheat temperature is increased. Noting that the temperature sensitivity of heat release is directly related to the activation energy, we use Law's approach to extract global activation energies and show that the deviations of κ from unity can be approximately correlated with β e f f . Finally, we show that significant improvements in entropy generation calculations can be obtained by estimating ∫ ( q ˙ / T ) d V using ( ∫ q ˙ d V ) / T p e a k , where T p e a k is the temperature at which the reaction rate peaks. This estimation leads to predictions of ∼5% within the exact value for the hydrocarbon cases but can still be in significant error for hydrogen at certain conditions.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43638148","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":"Experimental study of a slit in the presence of a bias flow under medium- and high-level acoustic excitations","authors":"Alessia Aulitto, A. Hirschberg, I. Lopéz Arteaga, Vertika Saxena","doi":"10.1177/17568277231167855","DOIUrl":"https://doi.org/10.1177/17568277231167855","url":null,"abstract":"This work presents an experimental investigation of the acoustic properties of a slit in the presence of a bias flow under moderate- and high-acoustic excitations. Impedance tube experiments are discussed for a geometry inspired by deep punching resulting in a cut in the plate. The acoustic transfer impedance of the plate is discussed for several bias flow velocities, acoustic excitation, and different frequencies. In the range considered for this study, a bias flow appears to have two main effects, globally enhancing the sound absorption of the plate and creating a protective layer downstream of the plate due to the interaction between the slits. A maximum of the enhancement factor is found at a specific ratio between the acoustic velocity and the bias flow velocity. Two simple asymptotic behaviors are found, dominated by the flow or by the acoustic excitation, respectively. The behavior of the inertance is complex. Globally the inertance decreases with decreasing flow Strouhal number while its dependency on the amplitude of the acoustic velocity is less obvious.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43337227","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":"Stability and structure of lean swirling spray flames with various degrees of prevaporization","authors":"Jiayi Wang, P. M. de Oliveira, R. Pathania, Ingrid El Helou, E. Mastorakos","doi":"10.1177/17568277231159173","DOIUrl":"https://doi.org/10.1177/17568277231159173","url":null,"abstract":"Achieving full premixing and complete evaporation in lean prevaporized premixed combustors is challenging as it depends on the spray injector characteristics, prevaporisation strategy, and flow conditions. This article experimentally explores the stability and structure of a turbulent swirling n-heptane spray flame under various degrees of prevaporization. The results show that preheating the air to 343 K and 393 K has little effect on the lean blow-off velocity, while recessing the fuel injection significantly decreases the lean stability limit. To correlate these limits, various attempts to define a Damköhler number were made, but unlike previous studies with no prevaporisation, the difficulty in defining laminar flame speed in the present case does not allow a single correlation to work for all degrees of prevaporization. Four stable cases that differ in equivalence ratio, air preheat temperature, and fuel injection recess are investigated using one-dimensional PDA, OH* chemiluminescence and CH 2 O-planar laser-induced fluorescence (PLIF). Cases without fuel injection recess or air preheat exhibit a conical-shaped heat release zone near the shear layers. Preheating the air to 393 K reduced the Sauter mean diameter, increased prevaporization, and enabled a second heat release zone downstream of the fuel injection. Recessing the fuel injection by 25 mm reduced droplet velocities and led to a semi-spherical instead of a conical heat release zone. The CH 2 O-PLIF signal without injection recess was high along the central axis and its distribution resembled that observed for spray jet flames. In contrast, with recessed spray injection, CH 2 O was mainly found outside the central recirculation zone and only appeared inside during lean blow-off; similar to previous work with premixed flames. These findings show that different methods of prevaporization, which only differ by subtle changes in droplet characteristics, strongly impact flame stability. The present data can be used for turbulent flame modelling focusing on sprays and finite-rate kinetics.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45708180","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":"Flame Transfer Functions of the Lean Burnout Zone of an RQL Combustion Chamber - Dynamic Response to Primary Zone and Mixing Port Velocity Fluctuations","authors":"Julian Renner, Martin March, Thuy An Do, Moritz Merk, C. Hirsch, T. Sattelmayer","doi":"10.1177/17568277231159172","DOIUrl":"https://doi.org/10.1177/17568277231159172","url":null,"abstract":"This article describes an experimental investigation of thermoacoustic flame transfer functions of the lean burnout zone of an rich–quench–lean combustion chamber. With spatial separation of the rich primary from the lean secondary dilution zone, the latter is independently examined. The multi-microphone-method was employed to characterize the combustor acoustic velocity response to acoustic forcing coming from the primary zone and the mixing ports. The lean secondary zone is then treated as a pure acoustic 3-port network element connected to a 2-port Rankine-Hugoniot flame element. Focusing only on heat release fluctuations due to velocity fluctuations, the former are described by two linear superimposed flame transfer functions as a function of the velocity fluctuations coming from the primary zone and the mixing ports, respectively. Based on a non-reacting and a reacting measurement the two flame transfer functions could be extracted from the experimental data. Within this research, flame transfer functions from the new acoustical approach are presented and compared with ones measured using chemiluminescence and a photomultiplier tube. It is found that the inverse diffusion flame in the burnout zone reacts to velocity fluctuations from the primary zone in the low frequency range and a clear low pass behavior is observed. The mixing port velocity fluctuations create a more broadband response. In the presented cases, the flame transfer functions calculated from chemiluminescence match those from the acoustic method very well.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48901105","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 geometrical parameters and use of porous material in a Helmholtz resonator on suppression of thermo-acoustic instabilities","authors":"N. Deshmukh, A. Ansari, Sharvil Degwekar, B. Paul, Rohit Unnikrishnan","doi":"10.1177/17568277231158900","DOIUrl":"https://doi.org/10.1177/17568277231158900","url":null,"abstract":"Thermo-acoustic instabilities are mainly formed due to in-phase superposition of non-uniform heat release and pressure variation in the combustors of gas turbines, rocket engines and other acoustically confined spaces. These instabilities not only damage the structural system but also reduce its combustion efficiency and heat transfer rate. Hence suppression of thermo-acoustic instabilities is a prominent requirement for stable and safe heat generation in the combustors. In this work, the Helmholtz resonator has been used to suppress the instability. The efficacy of the resonator has been further increased by the addition of absorptive material to it. This work concentrates on inspecting the influence of cavity volume, neck length and neck diameter of the Helmholtz Resonator and the thickness of the absorptive material in the damping process of thermo-acoustic instabilities. The experimentation was carried out for various combinations of resonator cavity volume, neck diameter and neck length, and the best combination was found to be 6 mm neck diameter with 20 mm neck length at 60% volume which provided an acoustic damping of around 30 dB. Further, it was noticed that the addition of absorptive material is effective at lower volumes of Helmholtz resonator, and with an increase in thickness of absorptive material beyond a certain limit, the damping ability of the resonator reduces.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45042517","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 direct numerical simulation analysis of localised forced ignition in turbulent slot jets of CH 4 /CO 2 blends","authors":"C. Turquand d’Auzay, N. Chakraborty","doi":"10.1177/17568277221149471","DOIUrl":"https://doi.org/10.1177/17568277221149471","url":null,"abstract":"The early stages of flame evolution following successful localised forced ignition of different CH 4 /CO 2 blends in a slot jet configuration have been analysed using three-dimensional direct numerical simulations. The simulations have been conducted for three different concentration levels of CO 2 in the fuel blend composed of CH 4 and CO 2 (ranging from 0% to 20% by volume). The effects of CO 2 concentration have been analysed based on five different energy deposition scenarios which include situations where the mean mixture composition at the ignitor varies, but not its location in space, whereas other cases represent the scenarios where the mean mixture composition within the energy deposition region remains constant, but its spatial location changes with CO 2 concentration. The most favourable region for successful flame development following thermal runaway, from the mixture composition standpoint (i.e. the highest flammability factor), has been found to be displaced close to the nozzle with an increase in CO 2 concentration. The flame development following thermal runaway exhibits initial growth of hot gas kernel followed by downstream advection and eventual flame propagation along with radial expansion with a possibility of flame stabilisation irrespective of the level of CO 2 concentration. The triple flame propagation has been found to play a key role in the upstream flame propagation and eventual stabilisation. The orientation of the local flame normal plays a key role in the flame stabilisation. The lift off height has been found to increase with increasing CO 2 concentration which also adversely affect flame stabilisation for high levels of CO 2 concentration.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48727735","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":"Incompressible versus compressible large eddy simulation for the identification of premixed flame dynamics","authors":"Alexander J Eder, Camilo F. Silva, M. Haeringer, J. Kuhlmann, W. Polifke","doi":"10.1177/17568277231154204","DOIUrl":"https://doi.org/10.1177/17568277231154204","url":null,"abstract":"The present work compares the respective advantages and disadvantages of compressible and incompressible computational fluid dynamics (CFD) formulations when used for the estimation of the acoustic flame response. The flame transfer function of a turbulent premixed swirl-stabilized burner is determined by applying system identification (SI) to time series data extracted from large eddy simulation (LES). By analyzing the quality of the results, the present study shows that incompressible simulations exhibit several advantages over their compressible counterpart with equal prediction of the flame dynamics. On the one hand, the forcing signals can be designed in such a way that desired statistical properties can be enhanced, while maintaining optimal values in the amplitude. On the other hand, computational costs are reduced and the implementation is fundamentally simpler due to the absence of acoustic wave propagation and corresponding resonances in the flame response or even self-excited acoustic oscillations. Such an increase in efficiency makes the incompressible CFD/SI modeling approach very appealing for the study of a wide variety of systems that rely on premixed combustion. In conclusion, the present study reveals that both methodologies predict the same flame dynamics, which confirms that incompressible simulation can be used for thermoacoustic analyses of acoustically compact velocity-sensitive flames.","PeriodicalId":49046,"journal":{"name":"International Journal of Spray and Combustion Dynamics","volume":null,"pages":null},"PeriodicalIF":1.6,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41556817","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}