深井条件下超高压射流钻头水动力学特性研究

HYDRODYNAMIC CHARACTERISTICS OF WATER JET WITH ULTRA-HIGH-PRESSURE ON BIT IN DEEP WELL

采用Reliablek -ε湍流模型对高压射流双流道钻头内高压高速三维流道进行了水动力学设计 ,并提出了“流体齿”的概念。通过计算获得了高围压井底条件下一股高压小排量射流和两股低压大排量射流相互作用时井底湍流场的流动规律。研究结果表明 ,该条件下的射流结构可划分为范围很小的核心高速区和速度衰减区 ,井底漫流区的厚度随着高压射流离井底距离的减小而增大。

The reliableκ εmodel was applied to hydrodynamics design of 3D flow channel at high pressure and high velocity in rock bit with dual flow channels. The concept of 'flow tooth' was put forward. The characteristics of complicated turbulence flow under the interaction of three strands of water jets at the bottom hole under the action of high confining pressure were obtained from calculation. The water jets include one strand of water jet with high pressure and small displacement features and two strands of water jets with low pressure and large displacement properties. The composition of this kind of water jet include a small high velocity core centre and a big velocity declining region. The depth of cross flow area around the bottom hole increased with the decrease of the standoff distance of the high pressure jet to the bottom hole. The fluids around the bit body and in the annulus were flowing in a spiral pattern.