Pub Date : 2024-05-01DOI: 10.1615/atomizspr.2024051640
Jie Huang, Jun Xia, Yong He, Zhihua Wang, Kefa Cen
The aim of the present study is to achieve direct simulation of the puffing of a multicomponent droplet using interface capturing approaches. A non-ideal multicomponent phase equilibrium model is used to determine the composition of boiled vapour. Firstly, the puffing of a two-miscible-component (ethanol:water=1:1 in wt.%) droplet in two-dimensional configuration is directly simulated. The distribution of ejected vapour is impacted by a rotating and shape oscillating satellite droplet. The ejected vapour contains much more ethanol than water, facilitating the transport of the volatile fuel component inside the droplet to the ambient air. The morphological changes to the droplet induced by puffing promote considerably the contact of the boiling surface with air, significantly increasing the scalar dissipation rate of vapour/air. The effects of the nucleation bubble location and droplet temperature on puffing were investigated. Secondly, the puffing of an emulsified three-component (ethanol/water in dodecane) droplet in two-dimensional configuration is simulated. Grid independency has been checked for both the two-miscible-component and three-component emulsified droplet cases. Depending on the water volume fraction in the sub-droplet, which varies from 10% to 70% and is the key parameter herein, both one and two breakups of the parent dodecane droplet are observed. The characteristics of the sub-droplet “invasion” towards the inside of the parent dodecane droplet are investigated, together with the puffing statistics on the puffing delay time, satellite droplet size, surface areas of both the sub- and parent droplets, and oscillation dynamics of the sub-droplet.
{"title":"Direct Puffing Simulation of Miscible and Emulsified Multicomponent Single Droplets","authors":"Jie Huang, Jun Xia, Yong He, Zhihua Wang, Kefa Cen","doi":"10.1615/atomizspr.2024051640","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051640","url":null,"abstract":"The aim of the present study is to achieve direct simulation of the puffing of a multicomponent droplet using interface capturing approaches. A non-ideal multicomponent phase equilibrium model is used to determine the composition of boiled vapour. Firstly, the puffing of a two-miscible-component (ethanol:water=1:1 in wt.%) droplet in two-dimensional configuration is directly simulated. The distribution of ejected vapour is impacted by a rotating and shape oscillating satellite droplet. The ejected vapour contains much more ethanol than water, facilitating the transport of the volatile fuel component inside the droplet to the ambient air. The morphological changes to the droplet induced by puffing promote considerably the contact of the boiling surface with air, significantly increasing the scalar dissipation rate of vapour/air. The effects of the nucleation bubble location and droplet temperature on puffing were investigated. Secondly, the puffing of an emulsified three-component (ethanol/water in dodecane) droplet in two-dimensional configuration is simulated. Grid independency has been checked for both the two-miscible-component and three-component emulsified droplet cases. Depending on the water volume fraction in the sub-droplet, which varies from 10% to 70% and is the key parameter herein, both one and two breakups of the parent dodecane droplet are observed. The characteristics of the sub-droplet “invasion” towards the inside of the parent dodecane droplet are investigated, together with the puffing statistics on the puffing delay time, satellite droplet size, surface areas of both the sub- and parent droplets, and oscillation dynamics of the sub-droplet.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"63 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140833454","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.2024051300
Jingqi Bu, Longfei Li, Fan Zhang, Shenghui Zhong, Zhuoxin Liu, Xifeng Liao, Linhao Fan, Kui Jiao, Qing Du
Collision and breakup are the two main processes of the inter-impingement spray within internal combustion engines. However, previous models have not comprehensively considered five collision regimes representing collision dynamics under high-pressure conditions, leading to deviations of Sauter mean diameter (SMD) and frequency of bouncing regime. Hence, this paper integrates an improved composite collision model for high-pressure conditions, incorporating all collision regimes and the generation of satellite droplets. Due to the significant dependence of collision regimes on the geometric relationships between collision pairs, this paper advocates the combined utilization of the composite collision model with the absolutely deterministic trajectory model. Furthermore, the calculation method of the breakup length Bl that separates the primary and secondary breakup is adapted to apply the hybrid KH-RT breakup model to inter-impingement sprays. Extensive validation of binary droplet collisions and inter-impingement sprays are conducted. The comparative analysis reveals that the conventional Bl overestimates the penetration, the simplified collision model overestimates the SMD, while the present model agrees well with experimental results. Results show that a slight increase in global SMD and a significant reduction in velocity after the impingement point. Downstream of the impingement point, SMD at the ends exceeds that in the middle when the impinging distance Sz > Bl, contrasting with the situation when Sz < Bl and closer to the impingement point. Moreover, the occurrence of the coalescence regime is more frequent during secondary break before the impingement point.
{"title":"An inter-impingement spray model considering binary droplet collision based on an open-source platform","authors":"Jingqi Bu, Longfei Li, Fan Zhang, Shenghui Zhong, Zhuoxin Liu, Xifeng Liao, Linhao Fan, Kui Jiao, Qing Du","doi":"10.1615/atomizspr.2024051300","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051300","url":null,"abstract":"Collision and breakup are the two main processes of the inter-impingement spray within internal combustion engines. However, previous models have not comprehensively considered five collision regimes representing collision dynamics under high-pressure conditions, leading to deviations of Sauter mean diameter (SMD) and frequency of bouncing regime. Hence, this paper integrates an improved composite collision model for high-pressure conditions, incorporating all collision regimes and the generation of satellite droplets. Due to the significant dependence of collision regimes on the geometric relationships between collision pairs, this paper advocates the combined utilization of the composite collision model with the absolutely deterministic trajectory model. Furthermore, the calculation method of the breakup length Bl that separates the primary and secondary breakup is adapted to apply the hybrid KH-RT breakup model to inter-impingement sprays. Extensive validation of binary droplet collisions and inter-impingement sprays are conducted. The comparative analysis reveals that the conventional Bl overestimates the penetration, the simplified collision model overestimates the SMD, while the present model agrees well with experimental results. Results show that a slight increase in global SMD and a significant reduction in velocity after the impingement point. Downstream of the impingement point, SMD at the ends exceeds that in the middle when the impinging distance Sz > Bl, contrasting with the situation when Sz < Bl and closer to the impingement point. Moreover, the occurrence of the coalescence regime is more frequent during secondary break before the impingement point.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"28 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061023","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.2024051100
Olawole Kuti, Keiya Nishida
Due to its higher oxygen content, biodiesel fuel could play a vital role in the achievement of emission control in the heavy-duty transportation sector. Waste cooking oil (WCO) obtained from various sources such as the food industry, restaurants, and sewers could provide sustainable means of producing low-carbon fuel such as biodiesel. In this research, WCO biodiesel and conventional diesel fuels were characterized fundamentally in terms of their spray and gas entrainment qualities under diesel-like engine conditions using laser-induced fluorescence and particle image velocimetry (LIF-PIV). The impact of fuel injection parameters such as injection pressure and nozzle diameter on the fuel's spray and gas entrainment characteristics were investigated. Furthermore, an empirical equation was used to determine the droplet sizes of the sprays at different injection conditions. For both fuels, spray breakup and atomization were enhanced with the droplet size decreasing as injection pressure increased from 100 to 300 MPa and as nozzle size decreased from 0.16 to 0.08 mm. As a result of higher viscosity and surface tension, it was observed that WCO biodiesel produced longer spray penetration and shorter spray angle than diesel fuel. Furthermore, the quantity of gas entrained by WCO biodiesel spray was lower. As a result of an increase in the surface area, the percentage of gas entrained at the side periphery of the spray increased as time proceeded while the percentage of gas entrained via the spray tip decreased. The combined effect of ultra-high injection pressure of 300 MPa with a smaller nozzle hole diameter of 0.08mm was observed to enhance gas entrainment processes.
{"title":"Effect of fuel types and injection conditions on spray formation and gas entrainment processes in diesel engine","authors":"Olawole Kuti, Keiya Nishida","doi":"10.1615/atomizspr.2024051100","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051100","url":null,"abstract":"Due to its higher oxygen content, biodiesel fuel could play a vital role in the achievement of emission control in the heavy-duty transportation sector. Waste cooking oil (WCO) obtained from various sources such as the food industry, restaurants, and sewers could provide sustainable means of producing low-carbon fuel such as biodiesel. In this research, WCO biodiesel and conventional diesel fuels were characterized fundamentally in terms of their spray and gas entrainment qualities under diesel-like engine conditions using laser-induced fluorescence and particle image velocimetry (LIF-PIV). The impact of fuel injection parameters such as injection pressure and nozzle diameter on the fuel's spray and gas entrainment characteristics were investigated. Furthermore, an empirical equation was used to determine the droplet sizes of the sprays at different injection conditions. For both fuels, spray breakup and atomization were enhanced with the droplet size decreasing as injection pressure increased from 100 to 300 MPa and as nozzle size decreased from 0.16 to 0.08 mm. As a result of higher viscosity and surface tension, it was observed that WCO biodiesel produced longer spray penetration and shorter spray angle than diesel fuel. Furthermore, the quantity of gas entrained by WCO biodiesel spray was lower. As a result of an increase in the surface area, the percentage of gas entrained at the side periphery of the spray increased as time proceeded while the percentage of gas entrained via the spray tip decreased. The combined effect of ultra-high injection pressure of 300 MPa with a smaller nozzle hole diameter of 0.08mm was observed to enhance gas entrainment processes.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"42 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140937985","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}
Twin-fluid atomizers are used to improve liquid atomization and spray dispersion to achieve higher combustion efficiency and reduce smoke emissions in a wide range of operations associated with industrial burners and gas-turbine combustors. This study aims to elucidate the effect of the mixing port length on the internal flow and atomization process, and to determine the optimum length of the mixing port within a wide operating range. A Volume of Fluid-Large Eddy Simulation (VOF-LES) method is conducted to investigate the multiphase flow behaviors in three types of twin-fluid atomizers with different mixing port lengths. Furthermore, the jet breakup processes are observed using a high-speed video camera. The results indicate that under a low liquid flow rate, annular flow occurred in the three types of atomizers. Moreover, the thickness of the annular liquid film becomes more uniform as the length of the mixing port increases. However, at high liquid flow rates, the jet behavior depends on the mixing port length. For the medium-length atomizer, the inner jet exhibits intense fluctuations and impinges on the inner wall of the mixing port, thus facilitating the breakup process. Among the three different mixing port lengths, the medium-length atomizer effectively strengthens the breakup of the jet, thus indicating that an optimal mixing port length exists for twin-fluid atomization. The results indicate that the jet flow behavior is affected significantly by the mixing port design, which feature different lengths, thus resulting in different levels of jet fluctuation and breakup processes
{"title":"Effect of Mixing Port Length on Internal Flow and Near-field Jet Characteristics of Twin-fluid Atomizers","authors":"Yicheng DENG, Wenjing XING, Yu JIN, Xianyin LENG, Kazunori SATO, Keiya NISHIDA, Yoichi OGATA, Sushil RAUT","doi":"10.1615/atomizspr.2024051254","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051254","url":null,"abstract":"Twin-fluid atomizers are used to improve liquid atomization and spray dispersion to achieve higher combustion efficiency and reduce smoke emissions in a wide range of operations associated with industrial burners and gas-turbine combustors. This study aims to elucidate the effect of the mixing port length on the internal flow and atomization process, and to determine the optimum length of the mixing port within a wide operating range. A Volume of Fluid-Large Eddy Simulation (VOF-LES) method is conducted to investigate the multiphase flow behaviors in three types of twin-fluid atomizers with different mixing port lengths. Furthermore, the jet breakup processes are observed using a high-speed video camera. The results indicate that under a low liquid flow rate, annular flow occurred in the three types of atomizers. Moreover, the thickness of the annular liquid film becomes more uniform as the length of the mixing port increases. However, at high liquid flow rates, the jet behavior depends on the mixing port length. For the medium-length atomizer, the inner jet exhibits intense fluctuations and impinges on the inner wall of the mixing port, thus facilitating the breakup process. Among the three different mixing port lengths, the medium-length atomizer effectively strengthens the breakup of the jet, thus indicating that an optimal mixing port length exists for twin-fluid atomization. The results indicate that the jet flow behavior is affected significantly by the mixing port design, which feature different lengths, thus resulting in different levels of jet fluctuation and breakup processes","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"36 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061141","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 : 2024-04-01DOI: 10.1615/atomizspr.2024048168
Jingeun Song, Taehoon Kim
Droplet size of sprinkler sprays is related to the rate of evaporation and penetration of a fire plume. However, sprinkler sprays have various droplet sizes even at one location. Therefore, it is essential to examine the droplet size distribution depending on the location to predict the fire suppression performance of the sprinkler spray. To examine the droplet size distribution of spray from a pendent sprinkler head, acrylic plates were installed around the sprinkler head and a gap was made on one side of the wall. A charge-coupled device camera was installed to capture the droplet images both on a plane parallel to the sprinkler frame arm and on a plane perpendicular to the frame arm. Droplet information was obtained by deriving the image from the brightness and gradient images extracted from the original image. Large droplets, exceeding 1.5 mm in diameter, were observed in the mainstream of the spray. The probability of observing small droplets decreased as the droplets moved downstream. Spherical droplets were observed in the mainstream of the frame arm direction, while nonspherical droplets were observed in the perpendicular direction to the frame arm because of high velocity. The number based cumulative distribution function (CDFs) fitted using the Rosin–Rammler distribution function provided the best fitting results. The volume CDFs fitted using the Rosin–Rammler distribution function yielded acceptable adjusted R2 values. In this case, the coefficient m related to Dv50 and the coefficient n related to the width of the distribution increased with increasing radial and vertical locations.
水喷淋装置喷出的水滴大小与火羽的蒸发速度和穿透力有关。然而，即使在同一地点，水喷淋装置喷出的水滴大小也各不相同。因此，必须研究不同位置的水滴大小分布，以预测水喷淋器喷雾的灭火性能。为了检测悬挂式水喷淋头喷出的水滴大小分布，在水喷淋头周围安装了丙烯酸板，并在墙的一侧留出了空隙。安装了电荷耦合器件摄像机，以捕捉平行于喷洒器框架臂的平面和垂直于框架臂的平面上的液滴图像。液滴信息是通过从原始图像中提取的亮度和梯度图像得出的。在喷雾的主流中观察到直径超过 1.5 毫米的大液滴。观察到小液滴的概率随着液滴向下游移动而降低。在框架臂的主流方向观察到球形液滴，而在垂直于框架臂的方向观察到非球形液滴，因为速度较快。使用 Rosin-Rammler 分布函数拟合的基于数量的累积分布函数 (CDF) 提供了最佳拟合结果。使用 Rosin-Rammler 分布函数拟合的体积 CDF 得到了可接受的调整 R2 值。在这种情况下，与 Dv50 有关的系数 m 和与分布宽度有关的系数 n 随着径向和纵向位置的增加而增大。
{"title":"Droplet Size Distribution Variation of Pendent Fire Sprinkler Spray Depending on the Measurement Location","authors":"Jingeun Song, Taehoon Kim","doi":"10.1615/atomizspr.2024048168","DOIUrl":"https://doi.org/10.1615/atomizspr.2024048168","url":null,"abstract":"Droplet size of sprinkler sprays is related to the rate of evaporation and penetration of a fire plume. However, sprinkler sprays have various droplet sizes even at one location. Therefore, it is essential to examine the droplet size distribution depending on the location to predict the fire suppression performance of the sprinkler spray. To examine the droplet size distribution of spray from a pendent sprinkler head, acrylic plates were installed around the sprinkler head and a gap was made on one side of the wall. A charge-coupled device camera was installed to capture the droplet images both on a plane parallel to the sprinkler frame arm and on a plane perpendicular to the frame arm. Droplet information was obtained by deriving the image from the brightness and gradient images extracted from the original image. Large droplets, exceeding 1.5 mm in diameter, were observed in the mainstream of the spray. The probability of observing small droplets decreased as the droplets moved downstream. Spherical droplets were observed in the mainstream of the frame arm direction, while nonspherical droplets were observed in the perpendicular direction to the frame arm because of high velocity. The number based cumulative distribution function (CDFs) fitted using the Rosin–Rammler distribution function provided the best fitting results. The volume CDFs fitted using the Rosin–Rammler distribution function yielded acceptable adjusted R2 values. In this case, the coefficient m related to Dv50 and the coefficient n related to the width of the distribution increased with increasing radial and vertical locations.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"56 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578672","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 : 2024-04-01DOI: 10.1615/atomizspr.2024051208
Ya Wang, Hualin Xiao, Min Chai, Kun Luo, Jianren Fan
Direct numerical simulation of lean fuel spray in a pre-vaporized, premixed model combustor is performed to investigate the effects of evaporating spray on turbulence characteristics under gas turbine-like conditions. The gas phase is solved in Eulerian frame and the droplets are tracked as Lagrangian particles. The evaporation process is described with a corrected infinite thermal conductivity model. The results show that evaporating spray which has almost completed evaporation in the premixing tube could significantly affect the local turbulent characteristic in the near-field area. With the existence of evaporating spray, the recirculation zones are evidently enhanced and expanded. For fluctuating fields, the increasement in axial component indicates an intensive turbulent disturbance caused by evaporating spray. Further analysis of energy spectrum shows that evaporating spray magnifies kinetic energy in the small scale. The evaporating spray globally increases the turbulent kinetic energy (TKE) along the radius. Through the budget of TKE, the detailed mechanism of TKE transport is observed. The convective transport and turbulent transport are enhanced apparently while production and viscous dissipation are abated. For the sub-viscous dissipation terms, evaporating spray can significantly depress squared dilatation thus reduces turbulence dissipation to internal energy. Evaporating spray performs to influence turbulence in many aspects.
{"title":"Effects of evaporating spray on near-field turbulence characteristics in a gas turbine-like model combustor","authors":"Ya Wang, Hualin Xiao, Min Chai, Kun Luo, Jianren Fan","doi":"10.1615/atomizspr.2024051208","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051208","url":null,"abstract":"Direct numerical simulation of lean fuel spray in a pre-vaporized, premixed model combustor is performed to investigate the effects of evaporating spray on turbulence characteristics under gas turbine-like conditions. The gas phase is solved in Eulerian frame and the droplets are tracked as Lagrangian particles. The evaporation process is described with a corrected infinite thermal conductivity model. The results show that evaporating spray which has almost completed evaporation in the premixing tube could significantly affect the local turbulent characteristic in the near-field area. With the existence of evaporating spray, the recirculation zones are evidently enhanced and expanded. For fluctuating fields, the increasement in axial component indicates an intensive turbulent disturbance caused by evaporating spray. Further analysis of energy spectrum shows that evaporating spray magnifies kinetic energy in the small scale. The evaporating spray globally increases the turbulent kinetic energy (TKE) along the radius. Through the budget of TKE, the detailed mechanism of TKE transport is observed. The convective transport and turbulent transport are enhanced apparently while production and viscous dissipation are abated. For the sub-viscous dissipation terms, evaporating spray can significantly depress squared dilatation thus reduces turbulence dissipation to internal energy. Evaporating spray performs to influence turbulence in many aspects.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"29 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140800273","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 : 2024-04-01DOI: 10.1615/atomizspr.2024050511
Alexander Ariyoshi Zerwas, Kerstin Avila, José Luis de Paiva, Roberto Guardani, Lydia Achelis, Udo Fritsching
Gas assisted atomization is typically used to produce metal powders for additive manufacturing. In these systems the primary atomization governs the powder size distribution, but it is experimentally challenging to investigate. In this study the primary atomization of a molten metal spray was monitored with a calibrated high-speed camera and digital image processing. The technique enabled the generation of spatio-temporal maps at different distances from the nozzle. Among the characteristics of the spray, mean values and standard deviation of the spray width along the spraying direction, and the frequency of the oscillation of the spray boundaries are presented. Statistically relevant spray asymmetries were identified, which can be caused by faulty spray operation in form of a localized metal solidification at the pouring nozzle. By systematically varying the gas temperature and the gas atomization pressure, it is shown that heating of the gas up to 573 K stabilizes the spraying process and enhances the liquid dispersion in the recirculation zone.
气体辅助雾化通常用于生产增材制造所需的金属粉末。在这些系统中，一次雾化控制着粉末的粒度分布，但要对其进行研究在实验上具有挑战性。在这项研究中，使用校准过的高速相机和数字图像处理技术对熔融金属喷雾的一次雾化进行了监测。该技术能够生成距离喷嘴不同距离的时空图。在喷雾特征中，介绍了沿喷射方向喷雾宽度的平均值和标准偏差，以及喷雾边界的振荡频率。研究发现了与统计相关的喷雾不对称现象，这种现象可能是由于浇注喷嘴处的局部金属凝固而导致的错误喷雾操作造成的。通过系统地改变气体温度和气体雾化压力，结果表明将气体加热到 573 K 可以稳定喷雾过程，并增强再循环区的液体分散。
{"title":"High-speed Video Image Analysis of Liquid Metal Atomization Process","authors":"Alexander Ariyoshi Zerwas, Kerstin Avila, José Luis de Paiva, Roberto Guardani, Lydia Achelis, Udo Fritsching","doi":"10.1615/atomizspr.2024050511","DOIUrl":"https://doi.org/10.1615/atomizspr.2024050511","url":null,"abstract":"Gas assisted atomization is typically used to produce metal powders for additive manufacturing. In these systems the primary atomization governs the powder size distribution, but it is experimentally challenging to investigate. In this study the primary atomization of a molten metal spray was monitored with a calibrated high-speed camera and digital image processing. The technique enabled the generation of spatio-temporal maps at different distances from the nozzle. Among the characteristics of the spray, mean values and standard deviation of the spray width along the spraying direction, and the frequency of the oscillation of the spray boundaries are presented. Statistically relevant spray asymmetries were identified, which can be caused by faulty spray operation in form of a localized metal solidification at the pouring nozzle. By systematically varying the gas temperature and the gas atomization pressure, it is shown that heating of the gas up to 573 K stabilizes the spraying process and enhances the liquid dispersion in the recirculation zone.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"98 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578769","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 : 2024-04-01DOI: 10.1615/atomizspr.2024051762
Cristina García Llamas, Merve Durubal, Arie Huijgen, Kay Buist, J. A. M. Kuipers, Maike Baltussen
Droplet-droplet interactions of highly viscous liquid suspensions have a major impact in industrial processes such as spray drying, fuel combustion or waste treatment. The efficiency of these processes depends heavily on the morphology of the droplets after the collision (i.e., surface area and volume). Although often encountered, the physical mechanisms overning merging and break-up of non-Newtonian droplets are largely unknown. It is therefore of paramount importance to gain a better understanding of the complex physics dominating the collision of non-Newtonian droplets. In this research, we investigate numerically the collision of droplets using the Local Front Reconstruction Method (LFRM) and the Volume of Fluid (VOF) method. The coalescence and stretching separation regime are studied using a xanthan solution, whose shear thinning rheology is described with the Carreau-Yasuda model. The capabilities of the two methods to capture the complex topological changes are assessed by a one-to-one comparison of the numerical results with experiments for near head-on collisions at various We numbers.
高粘度液体悬浮液的液滴间相互作用对喷雾干燥、燃料燃烧或废物处理等工业过程具有重大影响。这些过程的效率在很大程度上取决于碰撞后液滴的形态（即表面积和体积）。非牛顿液滴的合并和破裂的物理机制虽然经常出现，但在很大程度上还不为人所知。因此，更好地理解主导非牛顿液滴碰撞的复杂物理机制至关重要。在这项研究中，我们使用局部前沿重构法（LFRM）和流体体积法（VOF）对液滴碰撞进行了数值研究。我们使用黄原胶溶液研究了凝聚和拉伸分离机制，黄原胶溶液的剪切稀化流变是用 Carreau-Yasuda 模型描述的。通过将数值结果与不同 We 数下的近距离正面碰撞实验结果进行一对一比较，评估了这两种方法捕捉复杂拓扑变化的能力。
{"title":"NUMERICAL INVESTIGATION OF NON-NEWTONIAN DROPLET-DROPLET COLLISIONS USING VOLUME OF FLUID (VOF) AND THE LOCAL FRONT RECONSTRUCTION METHOD (LFRM)","authors":"Cristina García Llamas, Merve Durubal, Arie Huijgen, Kay Buist, J. A. M. Kuipers, Maike Baltussen","doi":"10.1615/atomizspr.2024051762","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051762","url":null,"abstract":"Droplet-droplet interactions of highly viscous liquid suspensions have a major impact in industrial processes such as spray drying, fuel combustion or waste treatment. The efficiency of these processes depends heavily on the morphology of the droplets after the collision (i.e., surface area and volume). Although often encountered, the physical mechanisms overning merging and break-up of non-Newtonian droplets are largely unknown. It is therefore of paramount importance to gain a\u0000better understanding of the complex physics dominating the collision of non-Newtonian droplets.\u0000In this research, we investigate numerically the collision of droplets using the Local Front Reconstruction\u0000Method (LFRM) and the Volume of Fluid (VOF) method. The coalescence and stretching\u0000separation regime are studied using a xanthan solution, whose shear thinning rheology is described\u0000with the Carreau-Yasuda model. The capabilities of the two methods to capture the complex topological\u0000changes are assessed by a one-to-one comparison of the numerical results with experiments for\u0000near head-on collisions at various We numbers.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"51 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140578767","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 explore the in-cylinder fuel injection and the subsequent spray dynamics of aviation fuel RP-3, the RP-3 spray macroscopic characteristics of single-hole injectors with different nozzle diameter under varied ambient pressures and injection pressures are investigated via diffuser back-illumination imaging (DBI) experimental method. The critical factors of the variability in spray characteristics response are pointed out by setting up a one-dimensional active subspace in this study, to perform synergistic effects via multivariable sensitivity analysis. It is revealed that compared with diesel, RP-3 spray edge shows more vortex structures, which is more susceptible to gas entrainment, especially for injector with larger nozzle diameter. While increasing injection pressure and ambient pressure will lead reduced vortex structures instead. Moreover, on the whole, RP-3 produces shorter spray penetration distances, larger spray cone angle, lower spray irregularity and smaller spray areas than diesel under same conditions. Based on multivariable sensitivity analysis, it is indicated that accordant with diesel fuel, injection pressure (Pin) and ambient pressure (Pb) are the controlling parameters for RP-3 spray penetration distance, and Pb is dominant on RP-3 spray cone angle. However, caused by cavitation intensity, RP-3 spray cone angle is more sensitive to nozzle diameter (φ) and cavitation number (Ca). Moreover, Pb dominates over the sensitivity of spray irregularity and spray area is mainly controlled by Pin.
{"title":"Investigation of RP-3 Spray Characteristics Based on Sensitivity Analysis and Active Subspace Construction","authors":"Junxin Jiang, Shenyong Gao, Houchang Chen, Jianjun Hou, Wenbin Yu, Wei Li, Feiyang Zhao","doi":"10.1615/atomizspr.2024050124","DOIUrl":"https://doi.org/10.1615/atomizspr.2024050124","url":null,"abstract":"To explore the in-cylinder fuel injection and the subsequent spray dynamics of aviation fuel RP-3, the RP-3 spray macroscopic characteristics of single-hole injectors with different nozzle diameter under varied ambient pressures and injection pressures are investigated via diffuser back-illumination imaging (DBI) experimental method. The critical factors of the variability in spray characteristics response are pointed out by setting up a one-dimensional active subspace in this study, to perform synergistic effects via multivariable sensitivity analysis. It is revealed that compared with diesel, RP-3 spray edge shows more vortex structures, which is more susceptible to gas entrainment, especially for injector with larger nozzle diameter. While increasing injection pressure and ambient pressure will lead reduced vortex structures instead. Moreover, on the whole, RP-3 produces shorter spray penetration distances, larger spray cone angle, lower spray irregularity and smaller spray areas than diesel under same conditions. Based on multivariable sensitivity analysis, it is indicated that accordant with diesel fuel, injection pressure (Pin) and ambient pressure (Pb) are the controlling parameters for RP-3 spray penetration distance, and Pb is dominant on RP-3 spray cone angle. However, caused by cavitation intensity, RP-3 spray cone angle is more sensitive to nozzle diameter (φ) and cavitation number (Ca). Moreover, Pb dominates over the sensitivity of spray irregularity and spray area is mainly controlled by Pin.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"33 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140312161","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 : 2024-03-01DOI: 10.1615/atomizspr.2024051051
Tinglan Tang, Tai Jin, Gaofeng Wang
In the present study, numerical simulations have been conducted to investigate the primary breakup of the liquid film in the gas-liquid pintle injector, using the volume of fluid (VOF) method with the adaptive mesh refinement to capture the gas-liquid interface. The film breakup and atomization characteristics in the pintle injector are studied by changing the structure parameters and the momentum ratio. The results show that increasing the radial liquid flow rate to raise the momentum ratio promotes the atomization performance while decreasing the axial gas flow rate deteriorates the atomization performance. The two methods of altering the momentum ratio both cause the spray angle to increase with the momentum ratio, but the first routine leads to a slower increase. With the increase of opening distance, the velocity of the liquid flow decreases, and the thickness of the liquid film increases significantly, making the film hard to break up. The skip distance negatively influences the film breakup and atomization when the skip distance exceeds one. Moreover, the hollow region of the spray is decreased with a longer skip distance, which is detrimental to fuel combustion.
{"title":"Numerical simulations of liquid film primary breakup in a pintle injector: a parametric study","authors":"Tinglan Tang, Tai Jin, Gaofeng Wang","doi":"10.1615/atomizspr.2024051051","DOIUrl":"https://doi.org/10.1615/atomizspr.2024051051","url":null,"abstract":"In the present study, numerical simulations have been conducted to investigate the primary breakup of the liquid film in the gas-liquid pintle injector, using the volume of fluid (VOF) method with the adaptive mesh refinement to capture the gas-liquid interface. The film breakup and atomization characteristics in the pintle injector are studied by changing the structure parameters and the momentum ratio. The results show that increasing the radial liquid flow rate to raise the momentum ratio promotes the atomization performance while decreasing the axial gas flow rate deteriorates the atomization performance. The two methods of altering the momentum ratio both cause the spray angle to increase with the momentum ratio, but the first routine leads to a slower increase. With the increase of opening distance, the velocity of the liquid flow decreases, and the thickness of the liquid film increases significantly, making the film hard to break up. The skip distance negatively influences the film breakup and atomization when the skip distance exceeds one. Moreover, the hollow region of the spray is decreased with a longer skip distance, which is detrimental to fuel combustion.","PeriodicalId":8637,"journal":{"name":"Atomization and Sprays","volume":"52 6 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2024-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140150708","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：