Numerical Simulation Of Jet Jet Jet Characteristics

In the drilling process, in order to improve the rate of penetration, it is important to take the debris which produced by bit and to avoid scraping rock repeatedly away from the bottom of the well effectively and timely. It is reasonable to make full use of fluidic factor for the diamond bit and tri-cone bit. Through hundreds of investigations and studies, on the same conditions, the self-sustained oscillation jet nozzle has more energy than the continuous jet. It takes effect in cleaning the bottom and breaking the rock.The thesis is the numerical simulation analysis of the self-sustained oscillation jet nozzle, making the principle of self-sustained oscillation jet in order to provide the theoretical basis. With the help of original self-sustained oscillation jet nozzle, ordinary self-sustained oscillation cavity in three dimensions is in numerical simulation and some characteristic of fluidic field and pulse characteristic at outlets are known. The evaluation theory is proposed with the help of variance and coefficient of standard deviation, which are quantitative parameter. For conventional pulse nozzle structure, to carry out the change from top to bottom nozzle size scale, the wall collision angle down and the upper collision wall parameters is in numerical simulation. Through the comparison, some parameter sensitivity rule of the jet is in conclusion. While the wall collision angle down is120°or the upper collision wall angle is90°, the pulse jet is more perfect, others are worse. Some influential factors are got, such as collision walls, pulse cavities and outlets. Some non-circular outlets and new types of self-sustained oscillation cavity are proposed and in numerical simulation. It shows that collision walls play a larger part than self-sustained oscillation cavities; new types of pulse jet nozzles are better than ordinary ones. Some conclusions on jet characteristic with the distance are summed up. With the help of breaking rule and fluidic characteristic of PDC bit and tri-cone bit, some principles on pulse nozzle are in analysis. The results in the thesis are full of guidance to the scientific design and rational application.