阻尼喷头动能分布试验及模型

Experiment and model of kinetic energy distribution of damping sprinkler

针对阻尼喷头外流场水力学特性研究较少的问题,该文研究了单位体积动能、动能强度与有无散水齿、不同喷嘴直径之间的关系。在工作压力分别为175、200、250和300 k Pa,喷嘴直径分别为3.6、4.0、4.4和4.8 mm下,采用激光雨滴谱仪对Nelson R33阻尼喷头的水滴直径、速度和数目等参数进行试验测试,并对试验结果分析及模型建立。结果表明：有无散水齿条件下的单位体积动能均有逐渐增大的趋势;距喷头相同测点处,单位体积动能随喷嘴直径的增大而减小;给出了有无散水齿下不同喷嘴阻尼喷头单位体积水滴动能分布模型,相关系数均在0.94以上;在距喷头0～4 m,不同喷嘴直径的动能强度较小且差值不超过0.002 W/m^2,在距喷头较远处,不同喷嘴直径的动能强度差值较大,最大差值达到0.006 W/m^2。有散水齿时,动能强度在不同压力下波动均比较小,差值不超过5%。该结果为进一步研究阻尼喷头外流场水力学特性提供理论依据。

According to that there are few researches for the external spraying characteristics of damping sprinkler, the paper studied kinetic energy per unit volume and kinetic energy intensity of the sprinkler with or without water sprinkling gear under different nozzle diameters. In order to study the kinetic energy distribution and its model of damping sprinkler, hydraulic parameters of damping sprinkler were tested under the operating pressure of 175, 200, 250 and 300 kP a with different nozzle diameter of 3.6, 4.0, 4.4 and 4.8 mm, respectively. The laser precipitation monitor（LPM） was used to measure the drop diameter and velocity. The result showed that kinetic energy per unit volume of the sprinkler without or with water sprinkling gear was small at the test location between 0 and 3 m along the sprinkler. Meanwhile the difference of kinetic energy per unit volume of the sprinkler without or with water sprinkling gear was small as well. Kinetic energy per unit volume of the sprinkler with water sprinkling gear was larger than the one without water sprinkling gear when the distance from the nozzle increased. And the variation range of kinetic energy per unit volume increased with the increasing of the distance from the sprinkler. Without water sprinkling gear, the difference of kinetic energy per unit volume was small for different nozzle diameters at the same distance from the sprinkler, but it was bigger under the condition with water sprinkling gear. At the same location from the sprinkler, kinetic energy per unit volume decreased with the increase of nozzle diameter. The models of kinetic energy per unit volume and kinetic energy intensity distribution were established. The correlation coefficient of kinetic energy per unit volume distribution model was above 0.94. The correlation coefficient of kinetic energy intensity distribution model was above 0.90. Kinetic energy intensity of the sprinkler with water sprinkling gear increased when the distance from the sprinkler increased. Without water sprinkling gear, kinetic energy intensity increased firstly, then gradually decreased, next increased again, and finally decreased rapidly to 0. Water sprinkling gear could make kinetic energy intensity reach the maximum in advance. Kinetic energy intensity was small at the test location between 0 and 2 m along the sprinkler with or without water sprinkling gear. The difference of kinetic energy intensity became larger when the distance was over 2 m. Compared to the sprinkler with water sprinkling gear, kinetic energy intensity of the sprinkler without water sprinkling gear under different working pressure was relatively small. With the distance from the sprinkler increasing, kinetic energy intensity showed a trend of increasing gradually firstly and then dropping to 0. The kinetic energy intensity under different nozzle diameters was small when the distance from the nozzle was 0-4 m and the difference was less than 0.002 W/m^2. When the distance from the nozzle was further, the kinetic energy intensity of the sprinkler for different nozzle diameters was different greatly, and the maximum difference reached 0.006 W/m^2. There was no obvious relationship between kinetic energy intensity and nozzle diameter with water sprinkling gear when the location from the sprinkler is same. The result provides certain academic value for studying the damping sprinkler＇s external spraying characteristics.