减弱节流器中颗粒冲蚀破坏措施的数值模拟

井下节流器是水力加砂压裂施工中的重要元件之一。对在节流器内壁面设置肋条以提高其抗冲蚀性能的方法,采用考虑颗粒-颗粒碰撞的离散颗粒硬球模型进行了数值模拟,并采用半实验关联式计算了节流器内壁面的冲蚀速率,进一步对肋条的几何参数进行了优化。结果表明,设置肋条不仅可以在壁面附近形成类似滚动轮子的流场结构,减弱连续相的流速,还可以将90%以上冲击颗粒的速度降低到0.5 m/s以下,从而明显地提高了节流器的抗冲蚀性能;同时,当肋条高度H为3 mm、宽度B与间距L相同(5 mm),布置4个肋条时可以达到相对最佳的抗冲蚀效果。

Numerical simulation on particles-caused erosion reducing method in throttleer

Downhole throttleer is one of the most important components during sand fracturing operation.The discrete particle hard sphere model which considers particle-particle interaction was used in the simulation of the anti-erosion performances of an erosion reducing method through setting ribs on the inner wall of throttleer.The erosion rate of the inner wall was calculated by employing semi-empirical formulations,and the rib geometrical parameters were further optimized.The results show that the continuous flow travels like a rolling wheel near the wall,which can reduce the velocity of continuous flow,and the velocity of more than 90% impact particles is limited under 0.5 m/s after setting ribs.The anti-erosion performance is improved obviously.The relative best anti-erosion performance can be achieved when 4 ribs are set with a height H of 3 mm,a width B of 5 mm,and an interval L of 5 mm between ribs.