论文部分内容阅读
借助Fluent软件,应用欧拉双流体模型,对平均粒径为18.7μm的超细BC干粉灭火剂在水平直管内的运动过程进行模拟,研究了载气入口速度与单位管长压降的关系,结果表明,当载气速度最小为5 m/s时,压降随气速减小而降低。结合管内的浓度固相体积分数分布和速度分布特性的分析可知:当气速较小时,灭火剂的体积分数分布呈管顶小、管底大,此时管顶速度大、管底速度小;气速增大时,灭火剂的体积分数分布呈圆环形,管内速度分布类似单相流,管内的剪切力、相间的曳力作用增强而导致压降增大。超细干粉输送流量一定时,每个输送流量下载气存在一个转捩速度,输送流量大,转捩速度大。将压降的计算值与试验值进行比较分析,两者的误差为-30%~+25%,该误差在允许范围内,表明选用的模型和计算方法准确性高,预测性好。
By using FLUENT software, Euler dual fluid model was used to simulate the movement process of ultrafine BC powder with an average particle diameter of 18.7μm in horizontal straight pipe. The relationship between the inlet velocity of carrier gas and the pressure drop per unit pipe length was studied. The results show that when the minimum carrier gas velocity is 5 m / s, the pressure drop decreases with decreasing gas velocity. According to the analysis of the distribution of solid volume fraction and the velocity distribution in the tube, it can be seen that when the gas velocity is small, the volume fraction distribution of the extinguishing agent is small at the top of the tube and large at the bottom of the tube. When the gas velocity increases, the volume fraction of fire extinguishing agent distributes circularly. The velocity distribution in the tube is similar to single-phase flow. The shear force in the tube and the drag force between the phases increase and the pressure drop increases. A certain amount of ultra-fine dry powder delivery, the carrier gas flow rate of each transfer there is a transfer speed, delivery flow, transfer speed. Comparing the calculated value of the pressure drop with the test value, the error between the two is -30% ~ + 25%. The error is within the allowable range, indicating that the selected model and calculation method have high accuracy and good predictability.