Flow, Turbulence and Combustion最新文献_第6页

High Speed Particle Image Velocimetry in a Large Engine Prechamber 大型发动机前腔中的高速粒子图像测速仪

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-09-12 DOI: 10.1007/s10494-024-00572-0

Aravind Ramachandran, Rajat Soni, Markus Roßmann, Marc Klawitter, Clemens Gößnitzer, Jakob Woisetschläger, Anton Tilz, Gerhard Pirker, Andreas Wimmer

{"title":"High Speed Particle Image Velocimetry in a Large Engine Prechamber","authors":"Aravind Ramachandran, Rajat Soni, Markus Roßmann, Marc Klawitter, Clemens Gößnitzer, Jakob Woisetschläger, Anton Tilz, Gerhard Pirker, Andreas Wimmer","doi":"10.1007/s10494-024-00572-0","DOIUrl":"10.1007/s10494-024-00572-0","url":null,"abstract":"<div><p>Planar velocity measurements using the particle image velocimetry technique have been performed at a repetition rate of 10 kHz in the prechamber of a large bore gas engine mounted on a rapid compression machine (RCM), to visualize the velocity fields in the non-reacting gas flow during a compression stroke. The prechamber investigated in this work is a prototype with modifications made to facilitate optical access, and it is mounted axially on the RCM combustion chamber. The parameters of the compression stroke in the RCM are set to achieve a compression ratio of 10. After removing outlying data based on pressure and piston displacement curves, PIV data from compression strokes were analyzed. The time-resolved velocity fields capture the formation and motion of a tumble vortex in the imaged plane. Mean flow fields obtained by phase averaging across the datasets are presented, showing the development of the flow field in the prechamber throughout the compression stroke. The data obtained will be used to validate CFD simulations.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 4","pages":"1003 - 1023"},"PeriodicalIF":2.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00572-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178757","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}

引用次数: 0

The Aerodynamic Breakup and Interactions of Evaporating Water Droplets with a Propagating Shock Wave 蒸发水滴的气动破裂及与传播冲击波的相互作用

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-09-05 DOI: 10.1007/s10494-024-00581-z

Zhiwei Huang, Ruixuan Zhu, Martin Davy

{"title":"The Aerodynamic Breakup and Interactions of Evaporating Water Droplets with a Propagating Shock Wave","authors":"Zhiwei Huang, Ruixuan Zhu, Martin Davy","doi":"10.1007/s10494-024-00581-z","DOIUrl":"10.1007/s10494-024-00581-z","url":null,"abstract":"<div><p>The aerodynamic breakup physics of water droplets in shock–laden flows are investigated in this study. One-dimensional numerical simulations based on a hybrid Eulerian–Lagrangian approach are performed to study the interactions between propagating shock waves and monodispersed evaporating water droplets with breakup. Two-way coupling for the interphase exchanges of mass, momentum, and energy is considered for the two-phase gas–droplet flows. Parametric study on the droplet evaporation, motion, heating, and breakup dynamics is performed, through considering initial droplet diameters of 20–80 μm and incident shock Mach numbers (<span>({M}_{0})</span>) of 1.3–4.0. The resultant initial droplet Weber numbers range between 10.0 and 4758.3, which cover the bag, bag-and-stamen, sheet stripping, and wave crest stripping breakup modes. The distance for breakup completion behind the transmitted shock and the resultant diameter all decrease with increased incident shock Mach number. When <span>({M}_{0})</span> ≥ 2.1, shock attenuation is also intensified with droplet diameter besides volume fraction under fixed droplet mass loading. Furthermore, net momentum transfer from the droplets to carrier gas (instead of in the opposite direction as extensively observed) occurs when <span>({M}_{0})</span> ≥ 2.1, mainly caused by the high temperature of post-shock gas and small diameter of broken droplets under strong incident shocks. A scale analysis shows that the momentum and energy transfer rates because of droplet evaporation have comparable magnitudes respectively to the counterparts from drag force and convective heat transfer. This is particularly true in the regions far off the shock front when <span>({M}_{0})</span> ≥ 2.1.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"114 1","pages":"243 - 273"},"PeriodicalIF":2.0,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178758","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}

引用次数: 0

Passive Control of Shock-Wave/Turbulent Boundary-Layer Interaction Using Spanwise Heterogeneous Roughness 利用横向异质粗糙度对冲击波/湍流边界层相互作用进行被动控制

IF 2.4 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-09-04 DOI: 10.1007/s10494-024-00580-0

Wencan Wu, Luis Laguarda, Davide Modesti, Stefan Hickel

引用次数: 0

Installation Effects on Jet Aeroacoustics 安装对喷气机空气声学的影响

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-09-03 DOI: 10.1007/s10494-024-00574-y

Peter Jordan, Ulf Michel

引用次数: 0

Computational Study of Laser-Induced Modes of Ignition in a Coflow Combustor 同流燃烧器中激光诱导点火模式的计算研究

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-19 DOI: 10.1007/s10494-024-00575-x

Donatella Passiatore, Jonathan M. Wang, Diego Rossinelli, Mario Di Renzo, Gianluca Iaccarino

{"title":"Computational Study of Laser-Induced Modes of Ignition in a Coflow Combustor","authors":"Donatella Passiatore, Jonathan M. Wang, Diego Rossinelli, Mario Di Renzo, Gianluca Iaccarino","doi":"10.1007/s10494-024-00575-x","DOIUrl":"10.1007/s10494-024-00575-x","url":null,"abstract":"<div><p>This study investigates laser-induced ignition in a model-rocket combustor through computational simulations. The primary focus is on characterizing successful and unsuccessful ignition scenarios and elucidating the underlying physical mechanisms. Large Eddy simulations (LESs) are utilized to explore laser-based forced ignition in a methane–oxygen combustor, with attention given to the intricate interplay of factors such as initial condition variability and turbulent flow field. Perturbations in laser parameters and initial flow conditions introduce stochastic behavior, revealing critical insights into ignition location relative to the fuel-oxidizer mixture. A significant methodological innovation lies in the adaptation of established image analysis techniques to track and monitor the transport of hot packets within the flow field. By extending these tools, the study provides insights into the interaction between ignition kernels and flammable gases, offering a more comprehensive understanding of the phenomenon. Results highlight the interplay between hydrodynamic ejections from the laser spark and turbulent fluctuations in the background flow. Indeed, the hydrodynamic ejection emanating from the laser spark, which typically plays a central role for isolated kernels in quiescent flows, competes with the entrainment velocity if its values are within the same order of magnitude and if the laser focal location is particularly close to the shear layer’s edge.\u0000</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 4","pages":"1055 - 1079"},"PeriodicalIF":2.0,"publicationDate":"2024-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178594","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}

引用次数: 0

Gradient Information and Regularization for Gene Expression Programming to Develop Data-Driven Physics Closure Models 基因表达编程的梯度信息和正则化，以开发数据驱动的物理闭合模型

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-15 DOI: 10.1007/s10494-024-00579-7

Fabian Waschkowski, Haochen Li, Abhishek Deshmukh, Temistocle Grenga, Yaomin Zhao, Heinz Pitsch, Joseph Klewicki, Richard D. Sandberg

{"title":"Gradient Information and Regularization for Gene Expression Programming to Develop Data-Driven Physics Closure Models","authors":"Fabian Waschkowski, Haochen Li, Abhishek Deshmukh, Temistocle Grenga, Yaomin Zhao, Heinz Pitsch, Joseph Klewicki, Richard D. Sandberg","doi":"10.1007/s10494-024-00579-7","DOIUrl":"10.1007/s10494-024-00579-7","url":null,"abstract":"<div><p>Learning accurate numerical constants when developing algebraic models is a known challenge for evolutionary algorithms, such as Gene Expression Programming (GEP). This paper introduces the concept of adaptive symbols to the GEP framework by Weatheritt and Sandberg (J Comput Phys 325:22–37, 2016a) to develop advanced physics closure models. Adaptive symbols utilize gradient information to learn locally optimal numerical constants during model training, for which we investigate two types of nonlinear optimization algorithms. The second contribution of this work is implementing two regularization techniques to incentivize the development of implementable and interpretable closure models. We apply <span>(L_2)</span> regularization to ensure small magnitude numerical constants and devise a novel complexity metric that supports the development of low complexity models via custom symbol complexities and multi-objective optimization. This extended framework is employed to four use cases, namely rediscovering Sutherland’s viscosity law, developing laminar flame speed combustion models and training two types of fluid dynamics turbulence models. The model prediction accuracy and the convergence speed of training are improved significantly across all of the more and less complex use cases, respectively. The two regularization methods are essential for developing implementable closure models and we demonstrate that the developed turbulence models substantially improve simulations over state-of-the-art models.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"114 1","pages":"145 - 175"},"PeriodicalIF":2.0,"publicationDate":"2024-08-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s10494-024-00579-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142178760","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}

引用次数: 0

A Comprehensive Study About Implicit/Explicit Large-Eddy Simulations with Implicit/Explicit Filtering 关于带有隐式/显式过滤功能的隐式/显式大型埃迪模拟的综合研究

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-12 DOI: 10.1007/s10494-024-00577-9

Pedro Stefanin Volpiani

{"title":"A Comprehensive Study About Implicit/Explicit Large-Eddy Simulations with Implicit/Explicit Filtering","authors":"Pedro Stefanin Volpiani","doi":"10.1007/s10494-024-00577-9","DOIUrl":"10.1007/s10494-024-00577-9","url":null,"abstract":"<div><p>A high-order computational fluid dynamics code was developed to simulate the compressible Taylor–Green vortex problem by means of large-eddy (LES) and direct numerical simulations. The code, BASIC, uses explicit central-differencing to compute the spatial derivatives and explicit low storage Runge–Kutta methods for the temporal discretization. Central-differencing schemes were combined with relaxation filtering or with splitting formulas to discretize convective derivative operators. The application of split forms to convective derivatives generally guarantees good stability properties with marginal dissipation. However, these types of schemes were found to be unsuited to perform implicit large-eddy simulations (ILES). The minimally dissipative schemes showed acceptance performance, only when combined with a sub-grid scale model. The relaxation-filtering strategy, on the other hand, although more dissipative, was proven to be more adequate to perform ILES. We showed that reducing the filter dissipation, by optimizing its damping function, has a positive impact in the flow solution. When performing ILES, the utilization of split formulas in conjunction with relaxation filtering has equally yielded promising results. This combined approach enhances numerical stability while preserving low levels of numerical dissipation.</p></div>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"113 4","pages":"891 - 922"},"PeriodicalIF":2.0,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937208","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}

引用次数: 0

Statistical Inference of Upstream Turbulence Intensity for the Flow Around a Bluff Body with Massive Separation 大分隔崖体周围水流上游湍流强度的统计推断

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-10 DOI: 10.1007/s10494-024-00573-z

Tom Moussie, Paolo Errante, Marcello Meldi

引用次数: 0

Correction to: Aero-structural Analysis of a Scramjet Technology Demonstrator Designed to Operate at an Altitude of 23 km at Mach 5.8 更正：设计在 23 公里高度以 5.8 马赫运行的 Scramjet 技术演示器的气动结构分析

IF 2 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-08 DOI: 10.1007/s10494-024-00569-9

Paulo César de Oliveira Júnior, João Carlos Arantes Costa Júnior, Paulo Gilberto de Paula Toro

引用次数: 0

Multi-cycle Direct Numerical Simulations of a Laboratory Scale Engine: Evolution of Boundary Layers and Wall Heat Flux 实验室规模发动机的多循环直接数值模拟：边界层和壁面热通量的演变

IF 2.4 3区工程技术

Flow, Turbulence and Combustion Pub Date : 2024-08-07 DOI: 10.1007/s10494-024-00576-w

Bogdan A. Danciu, George K. Giannakopoulos, Mathis Bode, Christos E. Frouzakis

{"title":"Multi-cycle Direct Numerical Simulations of a Laboratory Scale Engine: Evolution of Boundary Layers and Wall Heat Flux","authors":"Bogdan A. Danciu, George K. Giannakopoulos, Mathis Bode, Christos E. Frouzakis","doi":"10.1007/s10494-024-00576-w","DOIUrl":"https://doi.org/10.1007/s10494-024-00576-w","url":null,"abstract":"<p>Multi-cycle direct numerical simulations (DNS) of a laboratory-scale engine at technically relevant engine speeds (1500 and 2500 rpm) are performed to investigate the transient velocity and thermal boundary layers (BL) as well as the wall heat flux during the compression stroke under motored operation. The time-varying wall-bounded flow is characterized by a large-scale tumble vortex, which generates vortical structures as the flow rolls off the cylinder wall. The bulk flow is found to strongly affect the development of the BL profiles, especially at higher engine speeds. As a result, the large-scale flow structures lead to alternating pressure gradients near the wall, invalidating the flow equilibrium assumptions used in typical wall modeling approaches. The thickness of the velocity BL and of the viscous sublayer was found to scale inversely with engine speed and crank angle. The thermal BL thickness also scales inversely with engine speed but increases with in-cylinder temperature. In contrast, thermal displacement thickness, which is sometimes used as a proxy for thermal BL thickness, was found to decrease with increasing temperature in the bulk. Examination of the heat flux distribution revealed areas of increased heat flux, particularly at places characterized by strong flow directed towards the wall. In addition, significant cyclic variations in the surface-averaged wall heat flux were observed for both engine speeds. An analysis of the cyclic tumble ratio revealed that the cycles with lower tumble ratio values near top dead center (TDC), indicative of an earlier tumble breakdown, also exhibit higher surface averaged wall heat fluxes. These findings extend previous numerical and experimental results for the evolution of BL structure during the compression stroke and serve as an important step for future engine simulations under realistic operating conditions.</p>","PeriodicalId":559,"journal":{"name":"Flow, Turbulence and Combustion","volume":"58 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937209","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}

引用次数: 0