Spray nozzle is a key component in equipment for plant protection and water-saving irrigation. The fan nozzle is a kind of spray nozzle, which is widely used in agriculture and forestry for irrigation and control of d...Spray nozzle is a key component in equipment for plant protection and water-saving irrigation. The fan nozzle is a kind of spray nozzle, which is widely used in agriculture and forestry for irrigation and control of diseases, insects, and weeds. In consideration of the increasing velocity of the flow field, when the hydraulic pressure remains unchanged and the flow path becomes narrow, and because the increase of the velocity of spray drops can increase the penetrability of spray drops into the plant canopy, a kind of new fan nozzle with multi entries and simple inner structure was designed and the influences of its structure parameters on the inner flow field were analyzed using FLUENT software. The experimental results showed that the influence of the throat length on the inner flow field of the nozzle was insignificant, while the orifice grooving degree had a significant effect on inner flow field of the nozzle. The larger the grooving degree was, the smaller the pressure and velocity of internal flow field of the nozzle. The nozzle throat length had little influence on the velocity change of internal flow field. Positive correlation was shown between throat length and flow field velocity.展开更多
In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.S...In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.Simulations have been conducted in the frame of the SIMPLEC algorithm.The k-εturbulence model has been used to account for turbulent effects.The study shows that when the angle of the convergent section is less than 3°,it has a scarce effect on the dynamics of the jet of shotcrete;with the increase of the convergence angle,the shotcrete jet velocity decreases and the nozzle wear increases;when this angle is greater than 6°,the concrete outlet jet velocity is very small and the nozzle can easily be blocked.Experimental results are in good agreement with the outcomes of the numerical simulations,which indicates that the used approach is reliable.展开更多
采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于...采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于圆形喷孔,当喷射压力为15.0 MPa时,椭圆喷孔长短轴比为4的椭圆喷孔E2中异辛烷质量流量要比圆形喷孔大3.54%;在喷雾贯穿阶段,由于椭圆喷雾贯穿距离始终小于圆形喷雾,导致椭圆喷雾撞击壁面的时间延迟,当喷射压力为6.0 MPa时,椭圆喷孔E2的喷雾撞壁时间较圆形喷雾推迟0.14 ms;喷雾撞击壁面后,圆形喷雾的铺展半径和卷吸高度都要大于椭圆喷雾,这是因为圆形喷雾速度快,喷雾动量大,促进了喷雾的飞溅和反弹,但这种差异随着喷射压力的提高而减小.展开更多
为了对真空射流流场进行研究,应用Fluent软件并基于VOF（volume of fluid）方法、k-ε标准湍模型及PISO算法,对不同喷口直径及入射压力的直射式锥型流道喷嘴的射流流场速度和湍流运动分布进行了数值模拟分析.结果表明：1）入口压力相同...为了对真空射流流场进行研究,应用Fluent软件并基于VOF（volume of fluid）方法、k-ε标准湍模型及PISO算法,对不同喷口直径及入射压力的直射式锥型流道喷嘴的射流流场速度和湍流运动分布进行了数值模拟分析.结果表明：1）入口压力相同,喷嘴直径越大,射流与周围介质间的速度梯度越大,可促进射流的扩散和液滴破碎后的尺寸均匀分布;2）喷嘴直径一定,入口压力在10~15 MPa内,射流湍流强度分布达到最佳状态,射流流场较好;3）如果不考虑材料的溶解性,相对于三氯甲烷和四氯化碳,丙酮作为溶剂时的液体喷射雾化效果较好,适于制备质量较好的高分子薄膜.展开更多
文摘Spray nozzle is a key component in equipment for plant protection and water-saving irrigation. The fan nozzle is a kind of spray nozzle, which is widely used in agriculture and forestry for irrigation and control of diseases, insects, and weeds. In consideration of the increasing velocity of the flow field, when the hydraulic pressure remains unchanged and the flow path becomes narrow, and because the increase of the velocity of spray drops can increase the penetrability of spray drops into the plant canopy, a kind of new fan nozzle with multi entries and simple inner structure was designed and the influences of its structure parameters on the inner flow field were analyzed using FLUENT software. The experimental results showed that the influence of the throat length on the inner flow field of the nozzle was insignificant, while the orifice grooving degree had a significant effect on inner flow field of the nozzle. The larger the grooving degree was, the smaller the pressure and velocity of internal flow field of the nozzle. The nozzle throat length had little influence on the velocity change of internal flow field. Positive correlation was shown between throat length and flow field velocity.
基金financially supported by the Foundation of State Key Laboratory of Safety and Health for Metal Mines(2018-JSKSSYS-05).
文摘In this research,the dynamics of wet spray nozzles with different geometries,used to accelerate shotcrete,are investigated on the basis of a suitable three-dimensional mathematical model and related numerical method.Simulations have been conducted in the frame of the SIMPLEC algorithm.The k-εturbulence model has been used to account for turbulent effects.The study shows that when the angle of the convergent section is less than 3°,it has a scarce effect on the dynamics of the jet of shotcrete;with the increase of the convergence angle,the shotcrete jet velocity decreases and the nozzle wear increases;when this angle is greater than 6°,the concrete outlet jet velocity is very small and the nozzle can easily be blocked.Experimental results are in good agreement with the outcomes of the numerical simulations,which indicates that the used approach is reliable.
文摘采用流体体积-喷雾单向耦合(VOF-spray one way coupling)分析方法,在不同喷射压力下对缸内直喷汽油机(GDI)圆形和椭圆喷孔的内部流通特性和喷雾撞壁特性进行了模拟仿真研究.结果表明:同等压力条件下,椭圆喷孔出口处异辛烷质量流量大于圆形喷孔,当喷射压力为15.0 MPa时,椭圆喷孔长短轴比为4的椭圆喷孔E2中异辛烷质量流量要比圆形喷孔大3.54%;在喷雾贯穿阶段,由于椭圆喷雾贯穿距离始终小于圆形喷雾,导致椭圆喷雾撞击壁面的时间延迟,当喷射压力为6.0 MPa时,椭圆喷孔E2的喷雾撞壁时间较圆形喷雾推迟0.14 ms;喷雾撞击壁面后,圆形喷雾的铺展半径和卷吸高度都要大于椭圆喷雾,这是因为圆形喷雾速度快,喷雾动量大,促进了喷雾的飞溅和反弹,但这种差异随着喷射压力的提高而减小.
文摘为了对真空射流流场进行研究,应用Fluent软件并基于VOF（volume of fluid）方法、k-ε标准湍模型及PISO算法,对不同喷口直径及入射压力的直射式锥型流道喷嘴的射流流场速度和湍流运动分布进行了数值模拟分析.结果表明：1）入口压力相同,喷嘴直径越大,射流与周围介质间的速度梯度越大,可促进射流的扩散和液滴破碎后的尺寸均匀分布;2）喷嘴直径一定,入口压力在10~15 MPa内,射流湍流强度分布达到最佳状态,射流流场较好;3）如果不考虑材料的溶解性,相对于三氯甲烷和四氯化碳,丙酮作为溶剂时的液体喷射雾化效果较好,适于制备质量较好的高分子薄膜.
