Under engine cold-start conditions, gasoline injections result in fuel deposition on the cylinder surfaces, due to inhibited fuel vapourisation when the contact surfaces are cold. This can lead to the presence of unburnt hydrocarbons and the formation of soot. The Engine Combustion Network’s (ECN) Spray G impinging on a wall, under various temperature conditions, was investigated using surface temperature measurements a suite of optical diagnostics including Low-Coherence Interferometry (LCI). PACE20 under different injection and ambient temperatures was tested. The measurements reported are of non-reacting conditions, whereby the focus of the study is to analyse spray-wall interaction, prior to flame arrival. The experiments were performed inside a spray vessel under engine-relevant conditions, with sprays impinging on a temperature-controlled wall equipped with nine fast-response, surface thermocouples. The wall was placed 40 mm downstream from the injector to represent the typical distance between the piston surface and injector during cold-start injections in the intake cycle. The injector was mounted on a rotational stage, causing different regions of the plume to impinge on the thermocouple array. This enabled high spatial and temporal resolution of the surface temperature measurements. LCI was used for film thickness quantification, which provided insights on the film dynamics upon impingement and the evaporation rates. High-speed visualisation techniques further aided in the understanding of transient fuel distribution on the wall.
{"title":"A Study of Impinging Spray G on Transient Thermal Loading and Fuel1 Film Deposition","authors":"Meghnaa Dhanji, Zachary Buen, Logan White, Julien Manin, Lyle Pickett","doi":"10.1615/atomizspr.2024054862","DOIUrl":"https://doi.org/10.1615/atomizspr.2024054862","url":null,"abstract":"Under engine cold-start conditions, gasoline injections result in fuel deposition on the cylinder surfaces, due to inhibited fuel vapourisation when the contact surfaces are cold. This can lead to the presence of unburnt hydrocarbons and the formation of soot. The Engine Combustion Network’s (ECN) Spray G impinging on a wall, under various temperature conditions, was investigated using surface temperature measurements a suite of optical diagnostics including Low-Coherence Interferometry (LCI). PACE20 under different injection and ambient temperatures was tested. The measurements reported are of non-reacting conditions, whereby the focus of the study is to analyse spray-wall interaction, prior to flame arrival. The experiments were performed inside a spray vessel under engine-relevant conditions, with sprays impinging on a temperature-controlled wall equipped with nine fast-response, surface thermocouples. The wall was placed 40 mm downstream from the injector to represent the typical distance between the piston surface and injector during cold-start injections in the intake cycle. The injector was mounted on a rotational stage, causing different regions of the plume to impinge on the thermocouple array. This enabled high spatial and temporal resolution of the surface temperature measurements. LCI was used for film thickness quantification, which provided insights on the film dynamics upon impingement and the evaporation rates. High-speed visualisation techniques further aided in the understanding of transient fuel distribution on the wall.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"28 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142255581","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}
Pub Date : 2024-09-01DOI: 10.1615/atomizspr.2024051862
Raul Payri, JOSE M GARCIA-OLIVER, Ricardo Novella, Jose M. Pastor, Weiwei Shang, Dario López-Pintor
The present work focuses on the derivation and evaluation of a chemical kinetic mechanism of Primary Reference Fuel (PRF, binary blends of n-heptane and isooctane) with a homogeneous reactors approach starting from a detailed one. Results show that the optimized mechanism can replicate the results of the detailed one with high accuracy. The mechanism is integrated into a Computational Fluid Dynamics workflow combining a Reynolds-Averaged Navier–Stokes approach, a diffuse-interface spray and an unsteady flamelet progress variable combustion models. The workflow is validated against spray combustion measurements following the standards of the Engine Combustion Network (ECN). Test cases sweep binary blends of PRF fuels from pure n-heptane to pure iso-octane using an ECN Spray A nozzle. The model can provide accurate predictions of typical reacting spray metrics such as ignition delay and lift-off length, which have been evaluated following a reconstruction of the experimental methods of schlieren and OH* chemiluminescence. Different definitions of the previous combustion metrics have been compared. The model captures the decreasing reactivity with increasing iso-octane fraction, which results in flame stabilizing at much leaner conditions. However, deficiencies are observed for low reactivity cases, either with high PRF or low temperature cases.
{"title":"Application of an Optimized Mechanism of Primary Reference Fuel to Single Hole Sprays","authors":"Raul Payri, JOSE M GARCIA-OLIVER, Ricardo Novella, Jose M. Pastor, Weiwei Shang, Dario López-Pintor","doi":"10.1615/atomizspr.2024051862","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051862","url":null,"abstract":"The present work focuses on the derivation and evaluation of a chemical kinetic mechanism of Primary Reference Fuel (PRF, binary blends of n-heptane and isooctane) with a homogeneous reactors approach starting from a detailed one. Results show that the optimized mechanism can replicate the results of the detailed one with high accuracy. The mechanism is integrated into a Computational Fluid Dynamics workflow combining a Reynolds-Averaged Navier–Stokes approach, a diffuse-interface spray and an unsteady flamelet progress variable combustion models. The workflow is validated against spray combustion measurements following the standards of the Engine Combustion Network (ECN). Test cases sweep binary blends of PRF fuels from pure n-heptane to pure iso-octane using an ECN Spray A nozzle. The model can provide accurate predictions of typical reacting spray metrics such as ignition delay and lift-off length, which have been evaluated following a reconstruction of the experimental methods of schlieren and OH* chemiluminescence. Different definitions of the previous combustion metrics have been compared. The model captures the decreasing reactivity with increasing iso-octane fraction, which results in flame stabilizing at much leaner conditions. However, deficiencies are observed for low reactivity cases, either with high PRF or low temperature cases.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"8 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181921","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}
Pub Date : 2024-08-01DOI: 10.1615/atomizspr.2024052913
Weidong Yu, Shinan Chang, Shuoshuo Wang
Droplet collision is a basic phenomenon in numerous natural and industrial processes, while the understanding of collision dynamics is still lacking. In this work, a numerical investigation of off-center collision of two equal-sized water droplets is performed with the Weber number of 14 to 196 and impact parameter of 0 to 0.8. The incompressible Navier-Stokes equations are solved by the finite volume method. Volume of Fluid (VOF) method and adaptive mesh technique are used to capture the gas-liquid interface. Firstly, by comparing with reliable published experimental data, the reliability of the numerical results is verified. Then the shape evolution for coalescence, reflexive separation and stretching separation is described detailly. The effect of the Weber number and impact parameter on the collision of two equal-sized water droplets is analyzed. Moreover, the analysis of the surface energy and kinetic energy is conducted for the collision process. Furthermore, the dimensions of ligament and bridge for high impact parameter stretching separation are presented quantitatively. Finally, the collision outcome for the simulation cases in this work is depicted and discussed. This study is helpful for fundamentally understanding the mechanism of collision dynamics of droplets, as well as applying droplet collision model to related processes.
{"title":"Numerical Investigation of Off-center Collision between Two Equal-sized Water Droplets","authors":"Weidong Yu, Shinan Chang, Shuoshuo Wang","doi":"10.1615/atomizspr.2024052913","DOIUrl":"https://doi.org/10.1615/atomizspr.2024052913","url":null,"abstract":"Droplet collision is a basic phenomenon in numerous natural and industrial processes, while the understanding of collision dynamics is still lacking. In this work, a numerical investigation of off-center collision of two equal-sized water droplets is performed with the Weber number of 14 to 196 and impact parameter of 0 to 0.8. The incompressible Navier-Stokes equations are solved by the finite volume method. Volume of Fluid (VOF) method and adaptive mesh technique are used to capture the gas-liquid interface. Firstly, by comparing with reliable published experimental data, the reliability of the numerical results is verified. Then the shape evolution for coalescence, reflexive separation and stretching separation is described detailly. The effect of the Weber number and impact parameter on the collision of two equal-sized water droplets is analyzed. Moreover, the analysis of the surface energy and kinetic energy is conducted for the collision process. Furthermore, the dimensions of ligament and bridge for high impact parameter stretching separation are presented quantitatively. Finally, the collision outcome for the simulation cases in this work is depicted and discussed. This study is helpful for fundamentally understanding the mechanism of collision dynamics of droplets, as well as applying droplet collision model to related processes.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"21 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142181922","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}
Pub Date : 2024-08-01DOI: 10.1615/atomizspr.2024052328
Yanzhi Zhang, Ye Bian, Zonghan Zhang, Zihe Liu, Ming Jia
The Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) breakup model has been extensively utilized in fuel spray simulations. In the KH-RT model, there are five important empirical model parameters, which need to be calibrated carefully for different fuels under various operating conditions. In this work, the global sensitivity analysis of the model constants in the KH-RT breakup model reveals that the model constant for switching the KH and RT mechanisms, Cb, is a dominant parameter affecting the simulation accuracy with the variation of fuel type. To determine the optimal Cb for gasoline spray, the computational fluid dynamics (CFD) program of spray simulation is coupled with the evolutionary genetic algorithm to obtain a quantitative relationship between Cb and ambient density (ρamb). Compared with diesel spray, Cb for gasoline spray is reduced owing to its lower density, viscosity, and surface tension, making it easier for gasoline spray to form smaller droplets after injection. Therefore, the influence of fuel properties should be considered when optimizing Cb. By elucidating the correlation between the physical properties of different fuels and their respective optimal Cb values, this formula is extended to encompass dimethyl ether (DME), biodiesel, and methanol in the present study. The validation results affirm that the enhanced Cb formula effectively reproduces the evolution of the spray for a variety of fuels, aligning well with experimental measurements.
{"title":"Derivation of a universal constant set in the Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) breakup model for spray simulations of various fuels","authors":"Yanzhi Zhang, Ye Bian, Zonghan Zhang, Zihe Liu, Ming Jia","doi":"10.1615/atomizspr.2024052328","DOIUrl":"https://doi.org/10.1615/atomizspr.2024052328","url":null,"abstract":"The Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) breakup model has been extensively utilized in fuel spray simulations. In the KH-RT model, there are five important empirical model parameters, which need to be calibrated carefully for different fuels under various operating conditions. In this work, the global sensitivity analysis of the model constants in the KH-RT breakup model reveals that the model constant for switching the KH and RT mechanisms, Cb, is a dominant parameter affecting the simulation accuracy with the variation of fuel type. To determine the optimal Cb for gasoline spray, the computational fluid dynamics (CFD) program of spray simulation is coupled with the evolutionary genetic algorithm to obtain a quantitative relationship between Cb and ambient density (ρamb). Compared with diesel spray, Cb for gasoline spray is reduced owing to its lower density, viscosity, and surface tension, making it easier for gasoline spray to form smaller droplets after injection. Therefore, the influence of fuel properties should be considered when optimizing Cb. By elucidating the correlation between the physical properties of different fuels and their respective optimal Cb values, this formula is extended to encompass dimethyl ether (DME), biodiesel, and methanol in the present study. The validation results affirm that the enhanced Cb formula effectively reproduces the evolution of the spray for a variety of fuels, aligning well with experimental measurements.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"23 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141931646","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}
Pub Date : 2024-08-01DOI: 10.1615/atomizspr.2024053690
Grazia Lamanna, Bernhard Weigand, Christoph Steinhausen
The dynamics of near-critical single droplets allows to investigate the transition from two-phase to single-phase mixing under well-defined conditions, devoid of the additional complications due to drop-drop interactions and combustion. Recently, an empirical regime map was proposed to predict the evolution of microscopic transcritical droplets. The experiments show that classical evaporation remains the controlling mechanism over a wide range of supercritical ambient pressures and temperatures with respect to the critical point of the evaporating fluid. Moreover, the onset ambient pressure for the transition to single-phase mixing varies inversely with temperature. To explain this trend, the behavior of a single droplet at near-critical conditions is investigated theoretically by means of a Langmuir-type evaporation model, originally proposed by Young. The model incorporates a modified boundary condition due to the inclusion of gas kinetic effects close to the vapor-liquid interface. This advanced evaporation model is employed to reproduce analytically the above-mentioned regime map, showing a good agreement with experimental findings. The analysis also revealed that the onset of the single-phase mixing regime is associated to the quenching of the evaporation process. The latter is caused by the decrease of the evaporation coefficients, which control the mass transfer rate across the Knudsen layer. The resulting reduction in evaporative cooling leads to the rapid heating of the liquid droplet and to the disintegration of the material interface at the critical temperature.
{"title":"On the role of trancritical evaporation in controlling the transition from two-phase to single-phase mixing","authors":"Grazia Lamanna, Bernhard Weigand, Christoph Steinhausen","doi":"10.1615/atomizspr.2024053690","DOIUrl":"https://doi.org/10.1615/atomizspr.2024053690","url":null,"abstract":"The dynamics of near-critical single droplets allows to investigate the transition from two-phase to single-phase mixing under well-defined conditions, devoid of the additional complications due to drop-drop interactions and combustion. Recently, an empirical regime map was proposed\u0000to predict the evolution of microscopic transcritical droplets. The experiments show that classical evaporation remains the controlling mechanism over a wide range of supercritical ambient pressures and temperatures with respect to the critical point of the evaporating fluid. Moreover, the onset ambient pressure for the transition to single-phase mixing varies inversely with temperature. To explain this trend, the behavior of a single droplet at near-critical conditions is investigated theoretically by means of a Langmuir-type evaporation model, originally proposed by Young. The model incorporates a modified boundary condition due to the inclusion of gas kinetic effects close to the vapor-liquid interface. This advanced evaporation model is employed to reproduce analytically the above-mentioned regime map, showing a good agreement with experimental findings. The analysis also revealed that the onset of the single-phase mixing regime is associated to the quenching of the evaporation process. The latter is caused by the decrease of the evaporation coefficients, which control the mass transfer rate across the Knudsen layer. The resulting reduction in evaporative cooling leads to the rapid heating of the liquid droplet and to the disintegration of the material interface at the critical temperature.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"27 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142223978","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}
Pub Date : 2024-07-01DOI: 10.1615/atomizspr.2024049845
Maohui Su, Jiaqing Ding, Kai Liu, Cangsu Xu, Wenhua Zhou
The advantages of methanol as an alternative fuel have been well demonstrated. However, the difficulty of atomization restricts its practical application. Also, flash boiling and air-assisted injection have been shown to improve the atomization quality of fuels. In this work, the methanol spray characteristics with and without air assistance were experimentally investigated. The experimental conditions include flash-boiling and non-flash-boiling states. High-speed backlight imaging and a Malvern laser particle size analyzer were used to obtain the spray images and droplet sizes, respectively. The flash-boiling state caused a significant variation in spray morphology and the formation of high-concentration central plumes with greater velocity. Compared to the non-flash-boiling spray, the droplet size of the central plumes is larger, whereas the peripheral droplets have a smaller particle size. The droplet size of the air-assisted spray at normal temperature and pressure can reach approximately 3.5 μm, whereas that of the methanol spray without air assistance under a strong flash-boiling state is approximately 60 μm, indicating that air-assisted injection can significantly improve the atomization quality of methanol spray. Furthermore, because of the good atomization, the air-assisted methanol spray is significantly affected by evaporation at high temperatures, and no significant transition of a flash-boiling state was observed.
{"title":"Effect of flash boiling and air-assisted injection on methanol spray characteristics","authors":"Maohui Su, Jiaqing Ding, Kai Liu, Cangsu Xu, Wenhua Zhou","doi":"10.1615/atomizspr.2024049845","DOIUrl":"https://doi.org/10.1615/atomizspr.2024049845","url":null,"abstract":"The advantages of methanol as an alternative fuel have been well demonstrated. However, the difficulty of atomization restricts its practical application. Also, flash boiling and air-assisted injection have been shown to improve the atomization quality of fuels. In this work, the methanol spray characteristics with and without air assistance were experimentally investigated. The experimental conditions include flash-boiling and non-flash-boiling states. High-speed backlight imaging and a Malvern laser particle size analyzer were used to obtain the spray images and droplet sizes, respectively. The flash-boiling state caused a significant variation in spray morphology and the formation of high-concentration central plumes with greater velocity. Compared to the non-flash-boiling spray, the droplet size of the central plumes is larger, whereas the peripheral droplets have a smaller particle size. The droplet size of the air-assisted spray at normal temperature and pressure can reach approximately 3.5 μm, whereas that of the methanol spray without air assistance under a strong flash-boiling state is approximately 60 μm, indicating that air-assisted injection can significantly improve the atomization quality of methanol spray. Furthermore, because of the good atomization, the air-assisted methanol spray is significantly affected by evaporation at high temperatures, and no significant transition of a flash-boiling state was observed.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"73 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141784244","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}
To comprehensively deepen the understanding of the primary breakup mechanism of dual-layer rotating conical liquid sheets, the spray field of a dual-orifice pressure-swirl atomizer was photographed using a high-speed shadowing method. The relationship and mechanism of the influence of the pressure-drop change of primary and pilot flow channels, and dual-layer liquid sheets merging on spray morphology, spray cone angle, and liquid sheet surface fluctuations were investigated in detail based on the analysis of spray field pictures. Attention was focused on the disturbance wave-change mechanism of the dual-layer liquid sheet merging process. The study shows that changing the pressure drop in the primary and pilot flow channels lead to changes in spray pattern, spray cone angle, and liquid sheet surface fluctuations. Furthermore, the influence of pressure drop in the primary flow channel is dominant, and the change in liquid sheet surface fluctuations is related to the spray pattern. In the process of liquid sheet merging (after the inner liquid sheet reaches the expected spray cone angle) the spray cone angle of the outer liquid sheet reduces in size, and only after the dual-layer liquid sheets are in contact with each other do the amplitude of the surface fluctuations of the liquid sheet become significantly larger and generate more medium- and high-frequency scatter.
{"title":"Experimental study on the spray pattern and the merging process of dual-layer rotating conical liquid sheets","authors":"Lixin Shen, Shuangcheng Yang, Yangjun Zhang, Weilin Zhuge, Yuping Qian, Zunhua Zhang, Fei Xing","doi":"10.1615/atomizspr.2024052055","DOIUrl":"https://doi.org/10.1615/atomizspr.2024052055","url":null,"abstract":"To comprehensively deepen the understanding of the primary breakup mechanism of dual-layer rotating conical liquid sheets, the spray field of a dual-orifice pressure-swirl atomizer was photographed using a high-speed shadowing method. The relationship and mechanism of the influence of the pressure-drop change of primary and pilot flow channels, and dual-layer liquid sheets merging on spray morphology, spray cone angle, and liquid sheet surface fluctuations were investigated in detail based on the analysis of spray field pictures. Attention was focused on the disturbance wave-change mechanism of the dual-layer liquid sheet merging process. The study shows that changing the pressure drop in the primary and pilot flow channels lead to changes in spray pattern, spray cone angle, and liquid sheet surface fluctuations. Furthermore, the influence of pressure drop in the primary flow channel is dominant, and the change in liquid sheet surface fluctuations is related to the spray pattern. In the process of liquid sheet merging (after the inner liquid sheet reaches the expected spray cone angle) the spray cone angle of the outer liquid sheet reduces in size, and only after the dual-layer liquid sheets are in contact with each other do the amplitude of the surface fluctuations of the liquid sheet become significantly larger and generate more medium- and high-frequency scatter.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"65 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141745821","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}
Pub Date : 2024-06-01DOI: 10.1615/atomizspr.2024051683
Volfango Bertola
The sound generated by the impact of water drops on heated surfaces is studied experimentally, with the purpose to identify the sound features characteristic of the various impact morphologies. Whilst the sound of drops impacting on liquid surfaces has been investigated extensively, little attention was given to the sound of drops on solid, heated surfaces. The identification of sound features specific to different impact morphologies would enable the impact regime recognition without the need of high-speed imaging visual inspection, and can be used to train machine learning algorithms for automatic impact regime detection. Water drops were generated from a hypodermic needle suspended above a polished aluminium surface at temperatures between 100°C and 400°C, with impact Weber numbers ranging from 30 to 150. The sound generated upon impact was captured by a supercardioid condenser microphone, and compared with high-speed video recordings of the the impact. Results suggest different impact morphologies generate a sound with distinctive spectral features.
{"title":"Acoustic emission of water drops impacting on a heated surface","authors":"Volfango Bertola","doi":"10.1615/atomizspr.2024051683","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051683","url":null,"abstract":"The sound generated by the impact of water drops on heated surfaces is studied experimentally, with the purpose to identify the sound features characteristic of the various impact morphologies. Whilst the sound of drops impacting on liquid surfaces has been investigated extensively, little attention was given to the sound of drops on solid, heated surfaces. The identification of sound features specific to different impact morphologies would enable the impact regime recognition without the need of high-speed imaging visual inspection, and can be used to train machine learning algorithms for automatic impact regime detection. Water drops were generated from a hypodermic needle suspended above a polished aluminium surface at temperatures between 100°C and 400°C, with impact Weber numbers ranging from 30 to 150. The sound generated upon impact was captured by a supercardioid condenser microphone, and compared with high-speed video recordings of the the impact. Results suggest different impact morphologies generate a sound with distinctive spectral features.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"77 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141548124","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}
This study aims to improve the atomization effect of a liquid jet in crossflow. The atomizer consists of a single injection port, where the liquid and atomizing air are mixed and injected as a two-phase jet. This study used high-speed photographing, image processing, and optical thickness analysis to clarify the breakup mechanism of annular liquid film jets with different properties when they encountered crossflow. The results suggest that the uniformity of liquid film at the atomizer exit strongly dominate the jet breakup process. It was also found that the thickness of the liquid film formed at the exit of the short-mixing port atomizer is non-uniform, whereas the thickness of liquid film produced by the long-mixing port atomizer is relatively uniform, resulting in the spreading of the liquid film jet from the short-mixing port atomizer is larger. Based on the series of experimental results, it can be concluded that the uniformity of the annular liquid film jet is decisive for the atomization state of the two-phase jets in crossflow.
{"title":"Breakup behaviors of annular liquid jet from twin-fluid atomizers in crossflow","authors":"Wenjing XING, Sushil RAUT, Kazunori SATO, Keiya NISHIDA, Yoichi OGATA","doi":"10.1615/atomizspr.2024049599","DOIUrl":"https://doi.org/10.1615/atomizspr.2024049599","url":null,"abstract":"This study aims to improve the atomization effect of a liquid jet in crossflow. The atomizer consists of a single injection port, where the liquid and atomizing air are mixed and injected as a two-phase jet. This study used high-speed photographing, image processing, and optical thickness analysis to clarify the breakup mechanism of annular liquid film jets with different properties when they encountered crossflow. The results suggest that the uniformity of liquid film at the atomizer exit strongly dominate the jet breakup process. It was also found that the thickness of the liquid film formed at the exit of the short-mixing port atomizer is non-uniform, whereas the thickness of liquid film produced by the long-mixing port atomizer is relatively uniform, resulting in the spreading of the liquid film jet from the short-mixing port atomizer is larger. Based on the series of experimental results, it can be concluded that the uniformity of the annular liquid film jet is decisive for the atomization state of the two-phase jets in crossflow.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"48 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141194263","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}
Pub Date : 2024-05-01DOI: 10.1615/atomizspr.2024052018
Chetankumar Vegad, Said Idlahcen, Longxiang Huang, Gilles Cabot, Bruno Renou, Benjamin Duret, Julien Reveillon, Francois-Xavier Demoulin
The dense spray produced at the primary stage of atomization in a pressure-swirl atomizer is characterized in this work. The optically dense regime from continuous liquid stream to first step breakup into liquid structures is acquired using a two-photon planar laser-induced fluorescence (2p-PLIF) technique. A notable advantage of 2p-PLIF over conventional PLIF is the attenuation of multiple scattering by simultaneous absorption of two photons in an ultra-short pulse duration. This approach is able to capture the complex interface morphology of spray structures. A curvature-based analysis of near-field is carried out to predict far-field spray characteristics. This methodology was recently introduced by cite{Palanti2022} to investigate numerical simulation of atomizing liquid flows. The present work extends its application to experimental images. The atomization process is described through the curvature distribution in different regimes. The spray characteristics are predicted from the early stage of atomization and are reasonably comparable with those of direct measurement by Phase Doppler Anemometry (PDA) in the later stage of atomization. The present analysis shows how it is possible to obtain information about the dispersed phase of the spray in advance based on the dense spray curvature distribution.
{"title":"Planar two-photon fluorescence imaging of dense spray to estimate spray characteristics: application in pressure-swirl atomizers","authors":"Chetankumar Vegad, Said Idlahcen, Longxiang Huang, Gilles Cabot, Bruno Renou, Benjamin Duret, Julien Reveillon, Francois-Xavier Demoulin","doi":"10.1615/atomizspr.2024052018","DOIUrl":"https://doi.org/10.1615/atomizspr.2024052018","url":null,"abstract":"The dense spray produced at the primary stage of atomization in a pressure-swirl atomizer is characterized in this work. The optically dense regime from continuous liquid stream to first step breakup into liquid structures is acquired using a two-photon planar laser-induced fluorescence (2p-PLIF) technique. A notable advantage of 2p-PLIF over conventional PLIF is the attenuation of multiple scattering by simultaneous absorption of two photons in an ultra-short pulse duration. This approach is able to capture the complex interface morphology of spray structures. A curvature-based analysis of near-field is carried out to predict far-field spray characteristics. This methodology was recently introduced by cite{Palanti2022} to investigate numerical simulation of atomizing liquid flows. The present work extends its application to experimental images. The atomization process is described through the curvature distribution in different regimes. The spray characteristics are predicted from the early stage of atomization and are reasonably comparable with those of direct measurement by Phase Doppler Anemometry (PDA) in the later stage of atomization. The present analysis shows how it is possible to obtain information about the dispersed phase of the spray in advance based on the dense spray curvature distribution.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"39 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937986","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}
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