水力喷砂射孔喷嘴的数值模拟及试验研究

Numerical and Experimental Study for Convergent Nozzles of Hydraulic Sand-Blasting Perforation

针对收缩型喷嘴内部结构长径比（直线段长度与直径的比值）严重影响出口射流的冲蚀性能这一关键问题,研究了喷嘴内部射流加速机理,得出长径比是影响喷嘴出口射流速度的最主要因素之一;针对工程中5吋套管常用喷嘴结构,选取不同喷嘴直径和直线段长度,利用FLUENT软件计算了35组模型（直线段长度为6~12 mm,直径为4~6 mm）,结果表明：射流速度最大时喷嘴长径比存在一个最佳值,本次计算射流出口速度最大时长径比为1.8;实验室按照数值计算模型加工35个不同长径比喷嘴,利用粒子图像测速系统（PIV）进行非接触式试验,分析实验结果,揭示了长径比对喷嘴出口射流性能的影响规律,验证5吋套管常用喷嘴（总长度为17 mm、收缩角30°）出口射流最大时对应的长径比1.8,试验结果与数值模拟一致.

Aiming at the key problem that length-diameter ratio of convergent nozzle seriously affected erosion capability of water jet,acceleration mechanism of water jet within the jet nozzles is studied and length-diameter ratio of nozzle is the main factor to affect the acceleration of water jet.According to the structure of 5-inch casing the most commonly used nozzles in engineering,selecting the line segment length of 6～12 mm,a diameter of 4～6 mm.Numerical calculations were conducted for 35 group-type of convergent ejector nozzles by the FLUENT software.The results show that there is an optimum length-diameter ratio value for nozzles.Align to these calculations,when length-diameter ratio reaches 1.8,jet velocity is maximum.Different types of nozzles are machined following the numerical calculation model in the laboratory.Non-contact tests are done by the PIV.Testing results are consistent with numerical simulation results.It reveals the reasons that impact the jet acceleration performance under the different length-diameter ratios.