Experimental Thermal and Fluid Science最新文献

{"title":"Effect of ethylene-rich gas temperature on rotating detonation auto-initiation process","authors":"Qiaodong Bai,&nbsp;Han Qiu,&nbsp;Jiaxiang Han,&nbsp;Yuwen Wu,&nbsp;Fang Wang,&nbsp;Chunsheng Weng","doi":"10.1016/j.expthermflusci.2024.111246","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111246","url":null,"abstract":"<div><p>In this study, the propagation characteristics of a rotating detonation wave (RDW) between ethylene-rich gas and ambient air were investigated experimentally. The traditional pre-detonator initiation method was abandoned in the experiment, but the spontaneous combustion of high-temperature ethylene-rich gas and air was adopted. The RDW auto-initiated through the deflagration-to-detonation transformation (DDT) process. With an increase in the ethylene-rich gas temperature, the modes of RDW propagation appeared as delayed initiation, dual-wave collision, and fluctuating dual-wave collision modes. When the gas temperature was too high, a secondary detonation wave was produced near the head of the rotating detonation chamber (RDC), which affected the propagation efficiency and stability of the RDW. The increase in gas temperature expanded the equivalence ratio range of auto-initiation, which was due to the higher gas temperature, and more highly active components were precipitated.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111246"},"PeriodicalIF":3.2,"publicationDate":"2024-06-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141325041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 analysis on the flow patterns and conversion mechanisms of condensing flow with non-azeotropic mixtures in spiral tube","authors":"Zhongyun Tian ,&nbsp;Wenke Zheng ,&nbsp;Jiwei Guo ,&nbsp;Yaolong Wang ,&nbsp;Lei Wang ,&nbsp;Jie Chen ,&nbsp;Yiqiang Jiang","doi":"10.1016/j.expthermflusci.2024.111245","DOIUrl":"10.1016/j.expthermflusci.2024.111245","url":null,"abstract":"<div><p>The flow patterns have a significant impact on the flow and heat transfer characteristics of the working fluid, making it fundamental for the study of complex two-phase flows. To investigate the condensation flow pattern and flow pattern transformation mechanism with mixed hydrocarbon in a spiral tube, a two-phase flow pattern experimental system was designed. The effects of mass flux (196–540 kg/m⁻²·s⁻¹), vapor quality (0–1), and operating pressure (2–4 MPa) on flow patterns of methane/ethane/propane/isobutane mixed fluid in spiral tubes were analyzed. The results showed that with the increase in vapor quality, flow patterns such as bubbly flow, intermittent flow, wavy-stratified flow, and annular flow were observed in sequence. Additionally, through a comparative analysis of the experimental observations with existing flow pattern maps, a new flow pattern map tailored for the condensation two-phase flow of mixed hydrocarbon working fluids has been established. Based on the influence of inertial force, surface tension, gravity, shear force and other forces, Martinelli number, Soliman <em>We</em> and Soliman <em>Fr</em> are selected for the development of flow pattern conversion criteria. The new flow pattern map accurately predicts the majority of flow patterns.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111245"},"PeriodicalIF":3.2,"publicationDate":"2024-06-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141407873","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 elevated crossflow temperature on jet primary atomization","authors":"Zhao Gao,&nbsp;Yuying Liu,&nbsp;Guanghai Liu,&nbsp;Quan Zhang","doi":"10.1016/j.expthermflusci.2024.111254","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111254","url":null,"abstract":"<div><p>Liquid jet in hot gas crossflow is widely employed in industrial combustion devices, especially in the propulsion systems. In this work, the effect of elevated crossflow temperature on the primary atomization of a liquid jet is experimentally investigated, including breakup regime, surface wavelength, column breakup height, and near-field trajectory. The experiments are conducted at crossflow temperatures of 300 K and 500 K, with gas Weber number ranging from 8.82 to 67.55 and momentum flux ratio from 10 to 50. The gas Weber number and momentum flux ratio are kept constant via increasing the crossflow velocity when crossflow temperature increases. The results show that the elevated crossflow temperature weakens surface breakup, particularly at high momentum flux ratios, which makes the transition of breakup regime from column breakup to surface breakup require higher gas Weber number or momentum flux ratio. Besides, the elevated crossflow temperature leads to a slight increase in surface wavelength, column breakup height and near-field trajectory, with the increase in trajectory being more pronounced at lower gas Weber numbers. Finally, an empirical correlation for the near-field trajectory is obtained, including the effects of crossflow temperature, gas Weber number, and momentum flux ratio.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111254"},"PeriodicalIF":3.2,"publicationDate":"2024-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141328471","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Heat and mass transfer mechanistic investigation of wall intervention on spray ignition characteristics under aviation piston engine-like conditions","authors":"Dongfang Wang ,&nbsp;Qiming Ouyang ,&nbsp;Yikai Li ,&nbsp;Jilin Lei ,&nbsp;Yue Lou ,&nbsp;Zhongjie Shi ,&nbsp;Ziming Yang","doi":"10.1016/j.expthermflusci.2024.111247","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111247","url":null,"abstract":"<div><p>The interaction between spray and walls significantly influences the mixture formation and ignition characteristics in aviation piston engines, primarily due to the dynamics of heat and mass transfer. To elucidate the wall’s influence on the impingement spray ignition process and reconcile discrepancies in the extant literature, we conducted a comprehensive suite of optical experiments encompassing free and impinging sprays with wide ambient temperature conditions (680 to 1200 K). Numerical simulations were utilized to dissect the flow field’s distribution patterns, as well as heat and mass transfer dynamics. Our investigation reveals that impinging sprays exhibit markedly shorter ignition delay times than free sprays under comparable conditions, with this divergence becoming more pronounced at lower ambient temperatures. Notably, impingement sprays are capable of auto-ignition at reduced ambient temperatures. The spray-wall interaction effect accelerates the accumulation of heat from the low-temperature reaction, facilitating swifter attainment of the threshold temperature for the high-temperature reaction. This is attributable to the generation of a higher quantity of high-temperature mixtures with a diminished local equivalence ratio. The disparity in the ignition delay times between impinging and free sprays is exacerbated by the elevated heat demand for the transition from low-temperature reaction to high-temperature reaction at lower ambient temperature conditions, predominantly driven by the exothermic nature of low-temperature reaction.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111247"},"PeriodicalIF":3.2,"publicationDate":"2024-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141289370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 Study of spatiotemporal features of sweeping jets acting on afterbody vortices using low-operation-rate stereo PIV","authors":"Xiaodong Chen ,&nbsp;Shan Zhong ,&nbsp;Ozgun Ozer ,&nbsp;Andrew Kennaugh ,&nbsp;Tanghong Liu ,&nbsp;Guangjun Gao","doi":"10.1016/j.expthermflusci.2024.111244","DOIUrl":"10.1016/j.expthermflusci.2024.111244","url":null,"abstract":"<div><p>Although low-operation-rate particle image velocimetry (PIV) provides a good spatial accuracy in measurements at relatively affordable costs, it faces some challenges in capturing unsteady features of oscillatory flow. In this paper, a single sweeping jet actuated to control afterbody vortices from a 30^◦ slanted-base cylinder is investigated at a Reynolds number of 87,000. Phase-locked stereo PIV measurements combining triggering reference obtaining and real-time processing via field programmable gate array (FPGA) are leveraged to reveal the unsteady characteristics of the sweeping jet. The examined cases show that the phase-locked method can well identify jet’s spatiotemporal development process in each oscillation cycle. A sinusoidal-like interaction along phases between the jet and the afterbody vortex can be reasonably detected. At each moment, coherent small vortical structures form at the upper and bottom jet/ambient interfaces, which are caused by Kelvin-Helmholtz instability. Since the induced vortex has the same rotation direction as the afterbody vortex on each side, they merge with each other as the jet approaches the vortex, causing an increase in vorticity. Meanwhile, the sweeping jet’s intrusion into the vortex region induces a rise in turbulent kinetic energy in that area, causing turbulence ingestion of the vortex which weakens the velocity gradient. The sweeping behavior of the jet dominates the afterbody vortex to meander as the jet pushes its way underneath the vortex. The findings of this study provide encouraging evidence for future applications of sweeping jets in control of afterbody vortices.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111244"},"PeriodicalIF":3.2,"publicationDate":"2024-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141398041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 liquid–liquid dispersion patterns in T-inlet microchannels with different junction angles","authors":"Wang Cao ,&nbsp;Qingjun Yang ,&nbsp;Dongsheng Yang ,&nbsp;Xuan Wang ,&nbsp;Qi Mao","doi":"10.1016/j.expthermflusci.2024.111243","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111243","url":null,"abstract":"<div><p>Liquid-liquid two-phase flow in T-inlet microchannels with different junction angles (<em>θ</em> = 30°, 60°, 90°, 120° and 150°) was investigated experimentally. Four flow regimes of the dispersed phase were identified, i.e., parallel flow, jetting, dripping and squeezing, and the distribution of flow regimes for the dispersed phase corresponding to variations in the junction angle was plotted. The consequences of varying junction angle and flow conditions in the squeezing regime on the generated droplet size were analyzed. The results indicate that low capillary number and large flow rate ratio are conducive to the formation of large-size droplets. For constant flow conditions, junction angle <em>θ</em> = 90° is detrimental to the formation of squeezing microdroplets. The increase in microchannel junction angle causes the droplet size to decrease until <em>θ</em> &gt; 90°, where the droplet size increases with the junction angle. On the basis of experimental results, the scaling law correlation equations containing the junction angle for predicting the droplet length and droplet volume are proposed, respectively. The predicted values match well with the experimental data. The results of this work contribute to the enhancement of the monodispersity of microdroplets and the precise control over a wide range of the generated droplet size by adjusting the junction angle.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"158 ","pages":"Article 111243"},"PeriodicalIF":3.2,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141249752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 synthetic Schlieren method for laboratory measuring density profiles of a stratified fluid","authors":"Huixin Li ,&nbsp;Haihan Liu ,&nbsp;Duo Xu","doi":"10.1016/j.expthermflusci.2024.111242","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111242","url":null,"abstract":"<div><p>A synthetic Schlieren method is developed to measure the density field of a stratified fluid. A transparent sheet of background markers is attached on one side of a tank which is made of acrylic plates, and a camera is positioned on the opposite side of the tank. The markers are virtually displaced due to light refraction in the stratified fluid in the tank, in reference to those from the water tank. The governing equation is derived based on the observation that the marker displacements depend on the light refraction at the interface of media, the refractive indices of the transparent liquids and their spatial gradient. The density of the fluid is associated with the refractive index via the relationship obtained in a calibration process. We solve this governing equation, an over-determined system with only the target variable unknown, using the optimization method. We examine the present method by performing laboratory experiments for two cases of the density stratification, i.e., a linear stratification and a pycnocline. We also carry out ray tracing simulations of three characteristic density profiles (i.e., a linear stratification, a nonlinear stratification and a pycnocline). The present method is compared with the method of solving the Poisson equation in detail, emphasizing the difference between the two methods. Measurement uncertainty is discussed at last.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"157 ","pages":"Article 111242"},"PeriodicalIF":3.2,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141244597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Triad interactions investigated by dual wave component injection","authors":"Preben Buchhave ,&nbsp;Mengjia Ren ,&nbsp;Clara M. Velte","doi":"10.1016/j.expthermflusci.2024.111239","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111239","url":null,"abstract":"<div><p>The study of the exchange of momentum and energy between wave components of the turbulent velocity field, the so-called triad interactions, offers a unique way of visualizing and describing turbulence. Most often, this study has been carried out by direct numerical simulations or by power spectral measurements. Due to the complexity of the problem and the great range of velocity scales in high Reynolds number developed turbulence, direct measurements of the interaction between the individual wave components have been rare. In the present work, we present measurements and related computations of triad interactions between controlled wave components injected into an approximately laminar and uniform flow from an open wind tunnel by vortex shedding from two rods suspended into the flow. This results in two-dimensional interactions of three-dimensional turbulence, which makes the analysis of the triadic interactions considerably less complex to analyze than in a fully developed three-dimensional flow. With the information obtained from the computations, we are able to isolate the individual triad interactions contributing to the generated frequency components as the flow develops downstream as well as understanding, mapping out and predicting the strengths of these interactions. The analysis also provides the time constants governing the development of higher order frequency components. We are thus able to see the pattern of frequency combinations, the strengths of the individual mode combinations and the time sequence in which they occur. Any of the higher order combinations is not just the result of a single term in the Navier–Stokes Equation, but a combination of various previous combinations occurring with different strengths and in a varied pattern of generation. The combination of these experiments and computations thus provide unique insight into the inner workings of turbulence and shows how the nonlinear term in the Navier–Stokes equation on average forces the energy towards higher frequencies, which is the reason for the so-called energy cascade.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"157 ","pages":"Article 111239"},"PeriodicalIF":3.2,"publicationDate":"2024-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0894177724001080/pdfft?md5=c7a4da8b9f34af132d57f549514a9f22&pid=1-s2.0-S0894177724001080-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141244609","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Data repairing and resolution enhancement using data-driven modal decomposition and deep learning","authors":"Ashton Hetherington ,&nbsp;Daniel Serfaty ,&nbsp;Adrián Corrochano ,&nbsp;Julio Soria ,&nbsp;Soledad Le Clainche","doi":"10.1016/j.expthermflusci.2024.111241","DOIUrl":"https://doi.org/10.1016/j.expthermflusci.2024.111241","url":null,"abstract":"<div><p>This paper introduces a new series of methods which combine modal decomposition algorithms, such as singular value decomposition and high-order singular value decomposition, and deep learning architectures to repair, enhance, and increase the quality and precision of numerical and experimental data. A combination of two- and three-dimensional, numerical and experimental datasets are used to demonstrate the reconstruction capacity of the presented methods, showing that these methods can be used to reconstruct any type of dataset, showing outstanding results when applied to highly complex data, which is noisy. The combination of benefits of these techniques results in a series of data-driven methods which are capable of repairing and/or enhancing the resolution of a dataset by identifying the underlying physics that define the data, which is incomplete or under-resolved, filtering any existing noise. These methods and the <em>Python</em> codes are included in the first release of ModelFLOWs-app.<span>¹</span></p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"157 ","pages":"Article 111241"},"PeriodicalIF":3.2,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0894177724001109/pdfft?md5=858456a15bbabb6c56a44d121e8995ed&pid=1-s2.0-S0894177724001109-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141164235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Internal waves generated from asymmetric topographies","authors":"K. Hakes,&nbsp;J. Crockett","doi":"10.1016/j.expthermflusci.2024.111240","DOIUrl":"10.1016/j.expthermflusci.2024.111240","url":null,"abstract":"<div><p>Previous experimental and theoretical research on tidally generated internal waves over oceanic topography has often used symmetric topographic profiles. However, due to the complex nature of real ocean topography, the effect of asymmetry cannot be overlooked. Studies have shown that topographic complexities, including asymmetry, can have a significant impact on internal wave generation, but topographic asymmetry has not yet been explored in a systematic manner. This work presents a comparison of tidally generated internal waves from nine different two-dimensional asymmetric topographies, consisting of a steeper Gaussian curve on one side, and a wider Gaussian curve on the other. The amplitude of the wider curve varies from 60% of the steeper curve to its equivalent. Two oscillation frequencies are tested. Kinetic energy density in tidally generated internal waves on each side of the topography is compared qualitatively and quantitatively, in both physical and Fourier space. When compared to similar symmetric topographies, waves generated by the asymmetric topographies varied distinctly in both magnitude and wavenumber distribution of kinetic energy density. Waves on the relatively steep side of the topography contain up to 50% more kinetic energy than on the wider side. However, there is very little kinetic energy at the higher wavenumbers associated with the steeper topography. Instead, the internal wavefield is dominated by lower wavenumbers, 50%–90% of the kinetic energy density is contained in wavelengths corresponding to the wider side of the topography. Decreasing the amplitude of the wider curve does not make an appreciable difference in the kinetic energy density spectrum. Thus, the differences quantified here are due solely to changing slope and show the effect which relatively slight asymmetry has on internal wave generation.</p></div>","PeriodicalId":12294,"journal":{"name":"Experimental Thermal and Fluid Science","volume":"157 ","pages":"Article 111240"},"PeriodicalIF":3.2,"publicationDate":"2024-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141141492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}