Original Articles: 2014 Vol: 6 Issue: 3
A simplified mechanistic model for predicting the critical incipient velocity of cuttings in inclined pipes
By the analysis of cuttings transport mechanism, a simplified mechanistic model for predicting the critical incipient velocity of cuttings in the inclined pipe was presented in this paper based on the balance of force and moment. Drag coefficient calculation method was introduced into the model to improve the prediction accuracy. The incipient movement of different cuttings at certain angle was observed under different flow rate of water and glycerol solution. The numerical results of present model are in good agreement with experimental data and both of which indicate the domination of suspension transport mechanism at low inclination angle, and the domination of rolling transport mechanism in the range of medium angle to horizontal. By the analysis of rolling transport velocity and suspension transport velocity of the particle in X-Y axis, both of which are calculated by the model, we can get the change law of critical incipient velocity of cuttings in inclined pipes. In particular, the maximum critical incipient velocity of cuttings was reached at about 60°of inclination while the minimum value is reached at lower inclination angle. The position of minimum value was determined by drag coefficient, lift coefficient and inclination angle.