活塞冲锤主要参数对射流元件临界流速的影响

Effect of Main Parameters of Piston-Block Unit on Critical Flow Rate of Fluidic Element

应用CFD动态分析技术,以SC71B型射流式液动锤为研究对象,研究了活塞直径、活塞杆直径、活塞冲锤质量和行程对射流式液动锤射流元件临界流速的影响,并进行了实验验证。结果表明:理论预测值与实测值相对误差小于7.5%,精度远高于以往经验估计;射流元件临界流速随着活塞直径的增加而降低,随着活塞杆直径和活塞冲锤质量的增加而升高,与行程大小无关。以SC71B型射流式液动锤为例,为降低射流元件临界流速以减轻冲蚀,应设计40～42 mm的活塞直径、23～26 mm的活塞杆直径和11.2～23.5 kg的活塞冲锤质量。活塞直径增加23.5%时,射流元件临界流速降低了2/3;活塞杆直径增加60%时,射流元件临界流速提高了近4倍;活塞冲锤质量增加5倍时,射流元件临界流速只增加了1倍。

Taking the SC71B liquid-jet hammer as the study subject,the effects of diameters of pistons,the diameter of piston rods,mass of piston-block unit and stroke on the critical flow rate of the fluidic element in liquid-jet hammer are investigated using CFD dynamic analysis,and the simulation results are verified by experiments.It shows that the relative error between the simulated results and tested results is less than 7.5%,while the precision of the theoretical method based on CFD dynamic analysis is much higher than that of the empirical method.The results also show that the critical flow rate decreases with the increase of the diameter of the piston,while increases with the increase of the diameter of the piston rod or the mass of the piston-block unit,and is irrelative to stroke.Therefore,still using SC71B liquid-jet hammer as the example,pistons between 40 to 42 mm in diameter,piston rods between 23 to 26 mm in diameter and piston-block units between 11.2 to 23.5 kg in mass should be designed if expected erosion is to be decreased by lowering the critical flow rate.It is also found that when the piston diameter increases 23.5%,the critical flow rate reduces by 2/3.When the piston rod diameter increases by 60%,the critical flow rate increases nearly 4 times.When the mass of piston-block unit increases 5 times,the critical flow rate increases only 1 times.