Fine particulate matter produced during the rapid industrialization over the past decades can cause significant harm to human health.Twin-fluid atomization technology is an effective means of controlling fine particul...Fine particulate matter produced during the rapid industrialization over the past decades can cause significant harm to human health.Twin-fluid atomization technology is an effective means of controlling fine particulate matter pollution.In this paper,the influences of the main parameters on the droplet size,effective atomization range and sound pressure level(SPL)of a twin-fluid nozzle(TFN)are investigated,and in order to improve the atomization performance,a multi-objective synergetic optimization algorithm is presented.A multi-physics coupled acousticmechanics model based on the discrete phase model(DPM),large eddy simulation(LES)model,and Ffowcs Williams-Hawkings(FW-H)model is established,and the numerical simulation results of the multi-physics coupled acoustic-mechanics method are verified via experimental comparison.Based on the analysis of the multi-physics coupled acoustic-mechanics numerical simulation results,the effects of the water flow on the characteristics of the atomization flow distribution were obtained.A multi-physics coupled acoustic-mechanics numerical simulation result was employed to establish an orthogonal test database,and a multi-objective synergetic optimization algorithm was adopted to optimize the key parameters of the TFN.The optimal parameters are as follows:A gas flow of 0.94 m^(3)/h,water flow of 0.0237 m^(3)/h,orifice diameter of the self-excited vibrating cavity(SVC)of 1.19 mm,SVC orifice depth of 0.53 mm,distance between SVC and the outlet of nozzle of 5.11 mm,and a nozzle outlet diameter of 3.15 mm.The droplet particle size in the atomization flow field was significantly reduced,the spray distance improved by 71.56%,and the SPL data at each corresponding measurement point decreased by an average of 38.96%.The conclusions of this study offer a references for future TFN research.展开更多
It is a great challenge to find effective atomizing technology for reducing industrial pollution; the twin-fluid atomizing nozzle has drawn great attention in this field recently. Current studies on twin-fluid nozzles...It is a great challenge to find effective atomizing technology for reducing industrial pollution; the twin-fluid atomizing nozzle has drawn great attention in this field recently. Current studies on twin-fluid nozzles mainly focus on droplet breakup and single droplet characteristics. Research relating to the influences of structural parameters on the droplet diameter characteristics in the flow field is scarcely available. In this paper, the influence of a self-excited vibrating cavity structure on droplet diameter characteristics was investigated. Twin-fluid atomizing tests were performed by a self-built open atomizing test bench, which was based on a phase Doppler particle analyzer(PDPA). The atomizing flow field of the twin-fluid nozzle with a self-excited vibrating cavity and its absence were tested and analyzed. Then the atomizing flow field of the twin-fluid nozzle with different self-excited vibrating cavity structures was investigated.The experimental results show that the structural parameters of the self-excited vibrating cavity had a great effect on the breakup of large droplets. The Sauter mean diameter(SMD) increased with the increase of orifice diameter or orifice depth. Moreover, a smaller orifice diameter or orifice depth was beneficial to enhancing the turbulence around the outlet of nozzle and decreasing the SMD. The atomizing performance was better when the orifice diameter was2.0 mm or the orifice depth was 1.5 mm. Furthermore, the SMD increased first and then decreased with the increase of the distance between the nozzle outlet and self-excited vibrating cavity, and the SMD of more than half the atomizing flow field was under 35 μm when the distance was 5.0 mm. In addition, with the increase of axial and radial distance from the nozzle outlet, the SMD and arithmetic mean diameter(AMD) tend to increase. The research results provide some design parameters for the twin-fluid nozzle, and the experimental results could serve as a beneficial supplement to the twin-fluid nozzle study.展开更多
针对油浸式变压器瞬态流固耦合温度场求解存在模型自由度高导致耗时长达小时级的缺陷,构建了变压器数字孪生降阶模型,基于该模型可快速求解瞬态温度场。首先建立基于物联网(internet of things,IoT)的变压器数字孪生实现架构,搭建瞬态...针对油浸式变压器瞬态流固耦合温度场求解存在模型自由度高导致耗时长达小时级的缺陷,构建了变压器数字孪生降阶模型,基于该模型可快速求解瞬态温度场。首先建立基于物联网(internet of things,IoT)的变压器数字孪生实现架构,搭建瞬态流固耦合温度场伽辽金有限元全阶模型。其次,提出将本征正交分解(properorthogonal decomposition,POD)与有限元结合建立瞬态温度场降阶模型,并结合实测数据给出数字孪生建模与降阶计算流程。最后,开展实际变压器温升试验确保全阶模型准确性,并应用不同阶数降阶模型快速计算温度场分布,比较各阶模型的计算误差与时间。结果表明:计算值与实测值的温升误差绝对值满足在1.5℃以内;3阶模型计算结果与全阶模型结果符合POD误差规范要求;降阶模型与全阶模型相比其计算时间由小时级降至秒级。研究结果验证了降阶模型的准确性与时效性,可以在保证数字孪生模型求解精度的同时最大限度提高求解效率。展开更多
基金Supported by National Natural Science Foundation of China (Grant No.U21A20122)Zhejiang Provincial Natural Science Foundation of China (Grant No.LY22E050012)+2 种基金China Postdoctoral Science Foundation (Grant Nos.2023T160580,2023M743102)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems of China (Grant No.GZKF-202225)Students in Zhejiang Province Science and Technology Innovation Plan of China (Grant No.2023R403073)。
文摘Fine particulate matter produced during the rapid industrialization over the past decades can cause significant harm to human health.Twin-fluid atomization technology is an effective means of controlling fine particulate matter pollution.In this paper,the influences of the main parameters on the droplet size,effective atomization range and sound pressure level(SPL)of a twin-fluid nozzle(TFN)are investigated,and in order to improve the atomization performance,a multi-objective synergetic optimization algorithm is presented.A multi-physics coupled acousticmechanics model based on the discrete phase model(DPM),large eddy simulation(LES)model,and Ffowcs Williams-Hawkings(FW-H)model is established,and the numerical simulation results of the multi-physics coupled acoustic-mechanics method are verified via experimental comparison.Based on the analysis of the multi-physics coupled acoustic-mechanics numerical simulation results,the effects of the water flow on the characteristics of the atomization flow distribution were obtained.A multi-physics coupled acoustic-mechanics numerical simulation result was employed to establish an orthogonal test database,and a multi-objective synergetic optimization algorithm was adopted to optimize the key parameters of the TFN.The optimal parameters are as follows:A gas flow of 0.94 m^(3)/h,water flow of 0.0237 m^(3)/h,orifice diameter of the self-excited vibrating cavity(SVC)of 1.19 mm,SVC orifice depth of 0.53 mm,distance between SVC and the outlet of nozzle of 5.11 mm,and a nozzle outlet diameter of 3.15 mm.The droplet particle size in the atomization flow field was significantly reduced,the spray distance improved by 71.56%,and the SPL data at each corresponding measurement point decreased by an average of 38.96%.The conclusions of this study offer a references for future TFN research.
基金Supported by National Natural Science Foundation of China(Grant No.51705445)Hebei Provincial Natural Science Foundation of China,(Grant No.E2016203324)Open Foundation of the State Key Laboratory of Fluid Power and Mechatronic Systems of China(Grant No.GZKF-201714)
文摘It is a great challenge to find effective atomizing technology for reducing industrial pollution; the twin-fluid atomizing nozzle has drawn great attention in this field recently. Current studies on twin-fluid nozzles mainly focus on droplet breakup and single droplet characteristics. Research relating to the influences of structural parameters on the droplet diameter characteristics in the flow field is scarcely available. In this paper, the influence of a self-excited vibrating cavity structure on droplet diameter characteristics was investigated. Twin-fluid atomizing tests were performed by a self-built open atomizing test bench, which was based on a phase Doppler particle analyzer(PDPA). The atomizing flow field of the twin-fluid nozzle with a self-excited vibrating cavity and its absence were tested and analyzed. Then the atomizing flow field of the twin-fluid nozzle with different self-excited vibrating cavity structures was investigated.The experimental results show that the structural parameters of the self-excited vibrating cavity had a great effect on the breakup of large droplets. The Sauter mean diameter(SMD) increased with the increase of orifice diameter or orifice depth. Moreover, a smaller orifice diameter or orifice depth was beneficial to enhancing the turbulence around the outlet of nozzle and decreasing the SMD. The atomizing performance was better when the orifice diameter was2.0 mm or the orifice depth was 1.5 mm. Furthermore, the SMD increased first and then decreased with the increase of the distance between the nozzle outlet and self-excited vibrating cavity, and the SMD of more than half the atomizing flow field was under 35 μm when the distance was 5.0 mm. In addition, with the increase of axial and radial distance from the nozzle outlet, the SMD and arithmetic mean diameter(AMD) tend to increase. The research results provide some design parameters for the twin-fluid nozzle, and the experimental results could serve as a beneficial supplement to the twin-fluid nozzle study.
文摘针对油浸式变压器瞬态流固耦合温度场求解存在模型自由度高导致耗时长达小时级的缺陷,构建了变压器数字孪生降阶模型,基于该模型可快速求解瞬态温度场。首先建立基于物联网(internet of things,IoT)的变压器数字孪生实现架构,搭建瞬态流固耦合温度场伽辽金有限元全阶模型。其次,提出将本征正交分解(properorthogonal decomposition,POD)与有限元结合建立瞬态温度场降阶模型,并结合实测数据给出数字孪生建模与降阶计算流程。最后,开展实际变压器温升试验确保全阶模型准确性,并应用不同阶数降阶模型快速计算温度场分布,比较各阶模型的计算误差与时间。结果表明:计算值与实测值的温升误差绝对值满足在1.5℃以内;3阶模型计算结果与全阶模型结果符合POD误差规范要求;降阶模型与全阶模型相比其计算时间由小时级降至秒级。研究结果验证了降阶模型的准确性与时效性,可以在保证数字孪生模型求解精度的同时最大限度提高求解效率。
文摘利用PIV技术对气液两相流场与电场耦合作用下的外混式双流体雾化器荷电喷雾流场特性进行了测量研究,设计了一种带环形气幕的荷电感应装置,以控制喷雾射流在感应荷电过程中出现的液滴卷吸.结果表明:当水流量Q由20 L·h-1增加到36 L·h-1时,射流核心区速度增大,喷雾结构逐渐呈现非对称性,随着流量的增大非对称性越明显;扇形压力pR、雾化压力pB对喷雾流场的对称性及喷雾锥角的变化起重要作用;高压静电作用使得喷雾锥角略微增大,上卷吸现象明显并出现涡旋结构,长时间工作时电极环易积液;电极环气幕压力为100 k Pa时,其低压气流可以有效弱化细小液滴的上卷吸运动,解决电极环积液问题,荷电双流体雾化器运行稳定.
