Flow, Turbulence and Combustion最新文献

{"title":"Experimentally Closing the Balance of Progress of Reaction in Premixed Turbulent Combustion in the Thin Flame Regime","authors":"Yutao Zheng,&nbsp;Lee Weller,&nbsp;Simone Hochgreb","doi":"10.1007/s10494-024-00538-2","DOIUrl":"10.1007/s10494-024-00538-2","url":null,"abstract":"<div><p>We investigate the possibility of determining the local turbulent flame speed by measuring the individual terms in the balance of a mean progress of reaction variable for the case of a low turbulence methane-air Bunsen flame in the thin flame regime. Velocity distributions and flame edge positions were measured by particle image velocimetry techniques at 3 kHz for a flame stabilized by a surrounding pilot of the same stoichiometry, for a turbulent Reynolds number around 66 and Karlovitz numbers of the order of 4. The conservation equation for mean progress variable was analyzed along different streamlines as a balance of terms expressed as velocities, including terms for convection, turbulent diffusion, mean reaction, and turbulent and molecular diffusion. Each term was estimated from local velocities and flame locations using a thin flame approximation, and their uncertainty was evaluated based on propagation of experimentally measured statistical correlations. The largest terms were the convective and reaction terms, as expected, with smaller roles for turbulent and molecular diffusion across the flame brush. Countergradient diffusion and transition to gradient diffusion were observed across the flame brush. Closure of the balance of terms in the conservation equations using independently measured terms was not consistently achieved across the flame brush within the reckoned uncertainties, arriving at a balance within 20–30% of the absolute value. Testable hypotheses are offered for the possible reasons for the mismatch, including the role of spatial filtering and 3D effects on the reaction rate term. Finally, the experiments identify the inaccuracies in measuring a true local turbulent flame speed, and suggest a consistent methodology to reduce errors in such estimations. This is the first time such a detailed experimental closure is attempted for any configuration. The results suggest that the significant improvements in spatial resolution are necessary for a full closure.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 4","pages":"1215 - 1245"},"PeriodicalIF":2.0,"publicationDate":"2024-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00538-2.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140311383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"On the Definition of Reaction Progress Variable in Exhaust Gas Recirculation Type Turbulent MILD Combustion of Methane and n-Heptane","authors":"Khalil Abo-Amsha,&nbsp;Hazem S. A. M. Awad,&nbsp;Umair Ahmed,&nbsp;Nilanjan Chakraborty,&nbsp;Nedunchezhian Swaminathan","doi":"10.1007/s10494-024-00537-3","DOIUrl":"10.1007/s10494-024-00537-3","url":null,"abstract":"<div><p>Three-dimensional Direct Numerical Simulations of Exhaust Gas Recirculation (EGR)-type Moderate or Intense Low Oxygen Dilution (MILD) combustion of homogeneous mixtures of methane- and n-heptane–air have been conducted with skeletal chemical mechanisms. The suitability of different choices of reaction progress variable (which is supposed to increase monotonically from zero in the unburned gas to one in fully burned products) based on the mass fractions of different major species and non-dimensional temperature have been analysed in detail. It has been found that reaction progress variable definitions based on oxygen mass fraction, and linear combination of CO, CO₂, H₂ and H₂O mass fractions (i.e. <span>({c}_{O2})</span> and <span>({c}_{c})</span>) capture all the extreme values of the major species in the range between zero and one under MILD conditions. A reaction progress variable based on fuel mass fraction is found to be unsuitable for heavy hydrocarbons, such as n-heptane, since the fuel breaks down to smaller molecules before the major reactants (products) are completely consumed (formed). Moreover, it has been found that the reaction rates of <span>({c}_{O2})</span> and <span>({c}_{c})</span> exhibit approximate linear behaviours with the heat release rate in both methane and n-heptane MILD combustion. The interdependence of different mass fractions in the EGR-type homogeneous mixture combustion is considerably different from the corresponding 1D unstretched premixed flames. The current findings indicate that the tabulated chemistry approach based on premixed laminar flames may need to be modified to account for EGR-type MILD combustion. Furthermore, both the reaction rate and scalar dissipation rate of <span>({c}_{O2})</span> and <span>({c}_{c})</span> are found to be non-linearly related in both methane and n-heptane MILD combustion cases but the qualitative nature of this correlation for n-heptane is different from that in methane. This suggests that the range of validity of SDR-based turbulent combustion models can be different for homogeneous MILD combustion of different fuels.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 4","pages":"1191 - 1213"},"PeriodicalIF":2.0,"publicationDate":"2024-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00537-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140200651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advances in Combustion Research","authors":"Mohy S. Mansour,&nbsp;Nevin Selçuk,&nbsp;Federico Beretta,&nbsp;Andrea D’Anna","doi":"10.1007/s10494-024-00536-4","DOIUrl":"10.1007/s10494-024-00536-4","url":null,"abstract":"","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 3","pages":"671 - 672"},"PeriodicalIF":2.0,"publicationDate":"2024-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140228877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Systematic Adaptive Mesh Refinement Method for Large Eddy Simulation of Turbulent Flame Propagation","authors":"Benjamin Vanbersel,&nbsp;Francis Adrian Meziat Ramirez,&nbsp;Pavanakumar Mohanamuraly,&nbsp;Gabriel Staffelbach,&nbsp;Thomas Jaravel,&nbsp;Quentin Douasbin,&nbsp;Omar Dounia,&nbsp;Olivier Vermorel","doi":"10.1007/s10494-024-00534-6","DOIUrl":"10.1007/s10494-024-00534-6","url":null,"abstract":"<div><p>This paper presents a feature-based adaptive mesh refinement (AMR) method for Large Eddy Simulation of propagating deflagrations, using massive-scale parallel unstructured AMR libraries. The proposed method, named turbulent flame propagation-AMR (TFP-AMR), is able to track the transient dynamics of both the turbulent flame and the vortical structures in the flow. To handle the interaction of the turbulent flame brush with the vortical structures of the flow, a vortex selection criterion is derived from flame/vortex interaction theory. The method is built with the general intent to prioritise conservatively estimated parameters, rather than to rely on user-dependent parameters. In particular, a specific mesh adaptation triggering strategy is constructed, adapted to the strongly transient physics found in deflagrations, to guarantee that the physics of interest consistently reside within a region of high accuracy throughout the transient process. The methodology is applied and validated on several elementary cases representing fundamental bricks of the full problem: (1) a laminar flame propagation, (2) the advection of a pair of non-reacting vortices, (3) a flame/vortex interaction. The method is then applied to three different configurations of a three-dimensional complex explosion scenario in an obstructed chamber. All cases demonstrate the TFP-AMR capability to recover accurate results at reduced computational cost without requiring any <i>ad hoc</i> tuning of the AMR method or its parameters, thus demonstrating its genericity and robustness.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 4","pages":"1127 - 1160"},"PeriodicalIF":2.0,"publicationDate":"2024-03-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140053749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction to: Measurements in a Turbulent Channel Flow by Means of an LDV Profile Sensor","authors":"Saskia Pasch,&nbsp;Robin Leister,&nbsp;Davide Gatti,&nbsp;Ramis Örlü,&nbsp;Bettina Frohnapfel,&nbsp;Jochen Kriegseis","doi":"10.1007/s10494-024-00532-8","DOIUrl":"10.1007/s10494-024-00532-8","url":null,"abstract":"","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 1","pages":"215 - 216"},"PeriodicalIF":2.0,"publicationDate":"2024-02-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00532-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140004029","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Intrinsic Instabilities on the Response of Premixed Hydrogen/Air Conical Flames to Inlet Flow Perturbations","authors":"Linlin Yang,&nbsp;Yiqing Wang,&nbsp;Thorsten Zirwes,&nbsp;Feichi Zhang,&nbsp;Henning Bockhorn,&nbsp;Zheng Chen","doi":"10.1007/s10494-024-00535-5","DOIUrl":"10.1007/s10494-024-00535-5","url":null,"abstract":"<div><p>As a zero-carbon fuel, hydrogen is considered a promising alternative fuel. Hydrogen flames can be greatly affected by intrinsic instabilities including the diffusional-thermal instability (DTI) and Darrieus-Landau instability (DLI). Therefore, it is important to understand their properties, especially for cryogenic flames that are related to the safe utilization of liquid hydrogen. In this work, we conduct two-dimensional simulations of unsteady hydrogen/air conical flames to assess the effects of intrinsic instabilities, DTI and DLI, on the response of premixed hydrogen/air conical flames to inlet flow perturbations. The equivalence ratio and initial temperature are changed to respectively achieve different Lewis numbers (related to DTI) and expansion ratios (related to DLI). It is found that under certain conditions flame pinch-off occurs, during which a separated flame pocket is formed by the strong amplification of flame wrinkles generated by the inlet flow perturbations. The underlying mechanism of flame pinch-off enhancement due to DTI and DLI is different. For fuel-lean hydrogen/air at normal temperature, the flame front wrinkling is enhanced by strong DTI and it is the stretch-chemistry interaction that leads to flame pinch-off. However, for stoichiometric hydrogen/air at cryogenic temperature, there is a strong effect of DLI and flame pinch-off is mainly induced by flame-flow interaction. Moreover, downstream flow and flame speed near the separated flame pocket for flames exhibiting strong DTI and DLI are compared and the difference is analyzed. The findings indicate that intrinsic flame instability can amplify flame wrinkling and fluctuations in heat release rate, thereby contributing to flame pinch-off.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 4","pages":"1275 - 1297"},"PeriodicalIF":2.0,"publicationDate":"2024-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139988103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Comparative Study of Scarfed Nozzle for Jet-Installation Noise Reduction","authors":"Hasan Kamliya Jawahar,&nbsp;Mahdi Azarpeyvand","doi":"10.1007/s10494-023-00518-y","DOIUrl":"10.1007/s10494-023-00518-y","url":null,"abstract":"<div><p>The experimental investigation of the effects of scarfed nozzles on jet-installation noise was conducted using unheated subsonic jets in an anechoic jet noise facility. Four different types of scarfed nozzles with increasing nozzle lip angles were examined to study the installation effects at various plate distances away from the jet. Mach numbers ranging from 0.3 to 0.8 were investigated in the experiments. The use of scarfed nozzles is known to result in the deflection of flow away from the centre axis, inducing asymmetry in the jet shears, leading to azimuthal variation in the spectra, and ultimately, noise reduction. This study aims to explore the possibility of reducing jet-installation noise using scarfed nozzles at subsonic flow conditions. The characteristics of jet hydrodynamic pressure fluctuations were investigated in the axial direction using far-field measurements. The near-field flow features were studied using surface pressure transducers installed on the flat plate for the installed configurations. Detailed spectral, coherence, and correlation analyses were carried out to determine the noise reduction mechanisms associated with scarfed nozzles in the proximity of a flat plate. The results of the study showed that the use of scarfed nozzles significantly reduced the jet-installation noise. The reduction was attributed to the generation of an asymmetric flow field induced by the nozzle geometry. The reduction in noise levels was also observed to increase with increasing nozzle lip angle. The detailed analyses revealed that the noise reduction mechanism was associated with a decrease in the acoustic power generated by the jet. Overall, the results suggest that scarfed nozzles can be an effective means of reducing jet-installation noise in subsonic flow conditions.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 3","pages":"747 - 772"},"PeriodicalIF":2.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-023-00518-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139981254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Jet Noise and Wing Installation Effects of Circular, Beveled and Rectangular Nozzles","authors":"Julien Christophe,&nbsp;Julien de Decker,&nbsp;Christophe Schram","doi":"10.1007/s10494-024-00533-7","DOIUrl":"10.1007/s10494-024-00533-7","url":null,"abstract":"<div><p>With the growth of modern turbofan engines, their integration under the wing becomes challenging and induces aerodynamic and acoustic interactions between the jet exhaust and the airframe. Jet noise reduction techniques have been widely studied over the past decades but their efficiency has still to be demonstrated once installed. The present lab-scale jet experiments at Mach 0.6 compare the noise radiated by beveled and rectangular installed nozzles to circular ones on a quarter-sphere radiation map using a microphone antenna. For all radiation angles, modified nozzles show an amplitude decrease of the jet-plate interaction tones of the noise spectra attributed to a strong coupling between the jet shear layers and the sound scattering at the plate trailing edge. Beveled nozzles achieve a noise reduction for all radiation angles with a maximum decrease up to 2 dB at receiver locations perpendicular to the plate. While rectangular nozzles show a similar behavior, a sound increase is observed for listeners parallel to the plate when the height-to-width ratio is small.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 3","pages":"803 - 826"},"PeriodicalIF":2.0,"publicationDate":"2024-02-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00533-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139981595","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of the Large Local Specific Heat Capacity Impact on Turbulent Heat Transfer at Supercritical Pressure","authors":"Teng Wan,&nbsp;Pinghui Zhao,&nbsp;Yuanjie Li,&nbsp;Changhong Peng","doi":"10.1007/s10494-024-00529-3","DOIUrl":"10.1007/s10494-024-00529-3","url":null,"abstract":"<div><p>The specific heat capacity of supercritical fluids (SCFs) exhibits a sharp variation near the pseudo-critical temperature, resulting in the emergence of a localized region characterized by significantly large specific heat capacity within SCF flows. To comprehensively examine the influence of this prominent local specific heat capacity on turbulence and heat transfer in SCF flows, a series of direct numerical simulations are executed under supercritical pressure conditions, with an inlet bulk Reynolds number of <span>({Re}_{in}= 2700)</span>. Four cases sharing identical geometry yet differing in thermophysical properties are simulated and systematically compared after isolating the specific heat capacity from the other thermophysical factors. The findings reveal that the large local specific heat capacity results in heightened enthalpy fluctuations and fosters the enhancement of turbulent heat transfer. Furthermore, an observed quenching effect attributed to the substantial local specific heat capacity becomes evident within the near-wall region, stemming from fluctuations in thermal diffusivity. Notably, the decomposition of wall heat flux underscores the significant influence of the large local specific heat capacity on the primary turbulent heat flux governing SCF heat convection. The impact exhibits a nuanced complexity, simultaneously manifesting in a simultaneous increase in mean enthalpy gradient and reduction in turbulence.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"112 4","pages":"1027 - 1054"},"PeriodicalIF":2.0,"publicationDate":"2024-02-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139773602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simultaneous Measurements of Surface Spanwise Waves and Velocity in a Turbulent Boundary Layer","authors":"Isabella Fumarola,&nbsp;Matthew Santer,&nbsp;Jonathan Morrison","doi":"10.1007/s10494-024-00531-9","DOIUrl":"10.1007/s10494-024-00531-9","url":null,"abstract":"<div><p>Among the different passive and active techniques for skin friction drag reduction for turbulent boundary layers, near wall forcing through moving walls is one of the most promising techniques at low Re<span>(_tau)</span>. Fewer studies have looked at the mechanism at high Re<span>(_tau)</span>, closer to flight conditions, largely because, in this regime, numerical simulations become harder and experiments more challenging. To that end, there is the need of a systematic study for different surface waves and flow conditions. This work introduces a new model using a kagome lattice and an experimental setup which combines simultaneous measurements of surface displacement and velocity in the boundary layer. Here the results from a shortened version of the model at Re<span>(_tau approx)</span> 1000 are presented to demonstrate the capability of the experimental setup which is developed in view of further investigation at higher Reynolds number.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 1","pages":"139 - 158"},"PeriodicalIF":2.0,"publicationDate":"2024-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00531-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139770644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}