基于滑移网格方法的井下涡轮水动力性能仿真

Simulation on Hydrodynamic Performance of Downhole Turbine Based on Sliding Mesh Method

涡轮是钻井行业常用的一种机械结构,通常应用于井下涡轮发电机、涡轮钻具等。随着计算流体力学(CFD)理论与数值求解方法的不断拓展和革新,CFD方法已经成为井下涡轮性能研究的重要手段。目前针对井下涡轮的研究均是静态的。利用Fluent软件,采用滑移网格方法,编写UDF(user defined function)文件对井下涡轮进行动态仿真,研究了外界负载、叶片数量、流量、叶片安装角对井下涡轮水动力性能的影响,并对井下涡轮的启动特性和运动过程进行了分析。结果表明:启动力矩小于负载时,涡轮静止不动;涡轮所受的启动力矩大于负载时,涡轮开始转动。涡轮转动过程中涡轮所受力矩不断减小,而转速、冲击力不断增加。转速稳定时,流体产生的力矩与负载平衡,冲击力稳定。

Turbine is a common mechanical structure in drilling industry,which is usually used in downhole turbogenerator,turbodrill and so on.With the continuous development and innovation of computational fluid dynamics(CFD)theory and numerical methods,CFD method has been become an important means for the study of downhole turbine performance.At present,the research on downhole turbines is static.By using Flunt software and sliding mesh method,UDF(user defined function)file was compiled to simulate the dynamic performance of downhole turbine.The effects of external load,number of blades,flow rate and blade installation angle on the hydrodynamic performance of downhole turbine were studied,and the start-up characteristics and movement process of downhole turbine were analyzed.Results show that when the start-up moment is less than the load,the turbine is stationary.When the start-up moment is greater than the load,the turbine starts to rotate.In the process of the turbine’s rotation,the force moment of the turbine decreases,while the speed and impact force increase continuously.When the rotational velocity is stable,the torque produced by the fluid is balanced with the load,and the impact force is stable.