消防脉冲水枪喷嘴结构优化研究

Research on structure optimization for nozzle of fire pulse water gun

为了进一步提高脉冲水枪的灭火效率,采用CFD技术对维多辛斯基曲线结构、锥直结构和锥角结构3种喷嘴结构进行选型优化。CFD数值模型采用RNG k-ε方法模拟湍流,利用VOF模型追踪管道内部及外部流场的气液界面,研究了不同喷嘴结构对气液分布、能量转化、速度分布的影响,并结合水室中水的体积分数和出口速度曲线图对喷射周期进行分析。研究结果表明:维多辛斯基曲线结构射流周期T=14. 8 ms、锥直结构T=15. 4 ms、锥角结构T=17 ms;维多辛斯基曲线结构和锥直结构的出口速度衰减较缓慢,喷嘴前端的圆柱结构能提高射流速度的稳定性;维多辛斯基曲线结构喷嘴的出口速度更稳定、集束性更好、能量转化率更高,且产生的射流水柱呈锥式逐渐扩散,动能集中分布在轴线附近,能有效增大喷射距离,提高脉冲水枪的灭火效率。

In order to further improve the fire extinguishing efficiency of the pulse water gun,the model selection optimization on three types of nozzle structure including the Vidosinsky curve structure,cone straight structure and cone angle structure was carried out by using the CFD technology.In the CFD numerical model,the turbulence was simulated by using the RNG k-εmethod,and the gas-liquid interface between the internal and external flow fields of the pipeline was tracked by using the VOF model.The influence of different nozzle structures on the gas-liquid distribution,energy conversion and velocity distribution was discussed,and the jet cycle was analyzed by combining with the volume fraction of water and outlet velocity curve of the water chamber.The results showed that the jet cycles of the Vitosinsky curve structure,the cone straight structure and the cone angle structure were T=14.8 ms,T=15.4 ms,and T=17 ms,respectively.The outlet velocity attenuation of the Vitosinsky curve structure and the cone straight structure were slower,and the cylindrical structure at the front end of the nozzle could improve the stability of jet velocity.The nozzle with the Vidosinsky curve structure had the more stable outlet velocity,better bundling,and higher energy conversion rate.Besides,the generated jet water column presented the gradual diffusion with a cone shape,and the kinetic energy mainly concentrated near the axis,which could effectively increase the jet distance,and improve the fire extinguishing efficiency of the pulse water gun.