旋芯喷嘴结构及雾化特性研究
发布时间：2018-08-31 14:17
【摘要】：旋流式喷嘴是常用的雾化喷嘴结构形式,内置旋芯装置是产生旋流的有效结构形式,与其他类型喷嘴相比较,它因结构简单、中低压雾化效果好而被广泛应用于消防,环保和化工等领域。针对内置旋芯旋流喷嘴,基于先进的喷嘴综合测试台和CFD数值模拟技术,本文围绕旋芯喷嘴的结构及流场特性,进行了数值模拟和实验研究。分析了旋芯喷嘴的结构特点和雾化要求,并对喷嘴结构参数进行了改进设计;介绍了流体运动分析的方法及相应运动方程,着重分析了旋流喷嘴内部和外部流场运动状态,得到喷嘴内部速度、压力分布特性和喷嘴外部雾滴运动方程,理论分析了流场特性和旋流雾化机理。探讨了旋芯喷嘴CFD模拟的一般方法。在相同的速度进口和压力出口条件下,喷嘴模型作相应简化,旋芯分隔板长度等同为喷嘴进口直径,旋芯固定在直管段底部,认定旋芯整体为壁面,基于六面体结构网格对三维模型进行网格划分,选用标准k??湍流模型,采用连续介质-水进行稳态条件下的数值模拟。针对直通喷嘴和旋芯喷嘴,以及旋芯螺旋角、内锥角等旋芯结构参数变化,对喷嘴流场进行了数值模拟,分别就流场内速度、压力分布进行了对比分析。模拟结果表明,和普通直通喷嘴比较,旋芯喷嘴出口速度更大、速度分布更均匀,雾化效果更好,喷射距离更远;旋芯喷嘴出口轴向速度衰减更快,有了明显的切向速度,雾化锥角更大。由于流体回流和对空气的卷吸作用,喷嘴出口位置会形成一个空气锥,流体会形成膜状旋转喷出,使旋芯喷嘴显现空心锥的雾化特性。喷嘴Qg锥角为90°左右时,流体压损最小、回流相对较小、速度分布较均匀、轴向速度和切向速度相对较大,最为优化。旋芯螺旋角为15°左右时,喷嘴内部流场轴向速度和切向速度相对较大,压损较低,最为优化。基于喷嘴综合试验台,就直通喷嘴和内置旋芯喷嘴进行了对比实验研究,完成了流量特性实验和喷雾分布实验,获取了流量-压降关系曲线、雾化角-压降关系曲线和喷雾分布曲线,实验数据较好地验证了理论分析和数值模拟的结果。
[Abstract]:Swirl nozzle is a commonly used structure form of atomization nozzle, and the inner core device is an effective structure form for producing swirl flow. Compared with other types of nozzle, it is widely used in fire protection because of its simple structure and good atomization effect at medium and low pressure. Environmental protection and chemical industry. Based on advanced nozzle test bench and CFD numerical simulation technology, the structure and flow field characteristics of core nozzle are studied by numerical simulation and experiment. The structure characteristics and atomization requirements of the swirl nozzle are analyzed, and the structural parameters of the nozzle are improved. The method of fluid motion analysis and the corresponding motion equation are introduced, and the internal and external flow field motion state of the swirl nozzle is emphatically analyzed. The internal velocity and pressure distribution of the nozzle and the equation of droplet motion outside the nozzle are obtained. The characteristics of the flow field and the mechanism of swirl atomization are analyzed theoretically. The general method of CFD simulation of core nozzle is discussed. Under the condition of the same velocity inlet and pressure outlet, the nozzle model is simplified accordingly. The length of the spin-core separator is the same as the inlet diameter of the nozzle, and the rotary core is fixed at the bottom of the straight pipe section. Based on the hexahedron mesh, the 3D model is meshed, and the standard KG is chosen. The turbulent model is numerically simulated under steady state condition with continuous medium-water. The flow field of the nozzle is numerically simulated and the velocity and pressure distribution in the flow field are compared and analyzed according to the change of the structure parameters of the straight through nozzle and the core nozzle as well as the spiral angle and the inner cone angle of the rotary core. The simulation results show that the nozzle outlet velocity is larger, the velocity distribution is more uniform, the atomization effect is better, the injection distance is longer, the axial velocity attenuation is faster and the tangential velocity is obvious. The atomization cone angle is larger. Due to the reflux of the fluid and the entrainment of the air, an air cone will be formed at the outlet of the nozzle, and the fluid will form a membrane rotating jet, which will make the core nozzle show the atomization characteristics of the hollow cone. When the nozzle Qg cone angle is about 90 掳, the fluid pressure loss is minimum, the reflux is relatively small, the velocity distribution is more uniform, and the axial velocity and tangential velocity are relatively large. When the spiral angle of the core is about 15 掳, the axial and tangential velocity of the flow field in the nozzle is relatively large, and the pressure loss is relatively low. Based on the nozzle test bench, the flow characteristic experiment and spray distribution experiment were completed, and the flow-pressure drop curve was obtained. The atomization angle pressure drop relation curve and spray distribution curve are well verified by the experimental data and the results of the theoretical analysis and numerical simulation.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH136
本文编号：2215243
[Abstract]:Swirl nozzle is a commonly used structure form of atomization nozzle, and the inner core device is an effective structure form for producing swirl flow. Compared with other types of nozzle, it is widely used in fire protection because of its simple structure and good atomization effect at medium and low pressure. Environmental protection and chemical industry. Based on advanced nozzle test bench and CFD numerical simulation technology, the structure and flow field characteristics of core nozzle are studied by numerical simulation and experiment. The structure characteristics and atomization requirements of the swirl nozzle are analyzed, and the structural parameters of the nozzle are improved. The method of fluid motion analysis and the corresponding motion equation are introduced, and the internal and external flow field motion state of the swirl nozzle is emphatically analyzed. The internal velocity and pressure distribution of the nozzle and the equation of droplet motion outside the nozzle are obtained. The characteristics of the flow field and the mechanism of swirl atomization are analyzed theoretically. The general method of CFD simulation of core nozzle is discussed. Under the condition of the same velocity inlet and pressure outlet, the nozzle model is simplified accordingly. The length of the spin-core separator is the same as the inlet diameter of the nozzle, and the rotary core is fixed at the bottom of the straight pipe section. Based on the hexahedron mesh, the 3D model is meshed, and the standard KG is chosen. The turbulent model is numerically simulated under steady state condition with continuous medium-water. The flow field of the nozzle is numerically simulated and the velocity and pressure distribution in the flow field are compared and analyzed according to the change of the structure parameters of the straight through nozzle and the core nozzle as well as the spiral angle and the inner cone angle of the rotary core. The simulation results show that the nozzle outlet velocity is larger, the velocity distribution is more uniform, the atomization effect is better, the injection distance is longer, the axial velocity attenuation is faster and the tangential velocity is obvious. The atomization cone angle is larger. Due to the reflux of the fluid and the entrainment of the air, an air cone will be formed at the outlet of the nozzle, and the fluid will form a membrane rotating jet, which will make the core nozzle show the atomization characteristics of the hollow cone. When the nozzle Qg cone angle is about 90 掳, the fluid pressure loss is minimum, the reflux is relatively small, the velocity distribution is more uniform, and the axial velocity and tangential velocity are relatively large. When the spiral angle of the core is about 15 掳, the axial and tangential velocity of the flow field in the nozzle is relatively large, and the pressure loss is relatively low. Based on the nozzle test bench, the flow characteristic experiment and spray distribution experiment were completed, and the flow-pressure drop curve was obtained. The atomization angle pressure drop relation curve and spray distribution curve are well verified by the experimental data and the results of the theoretical analysis and numerical simulation.
【学位授予单位】：武汉工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TH136
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