Numerical simulation study on the influence of bend diameter rate on the flow characteristics of nature gas hydrate particles.

Bend pipe is a common part of long distance pipeline. There is very important to study the flow law of hydrate particles in the bend pipe, and pipeline design will be optimized. In addition, the efficiency and safety of pipeline gas transmission will be improved. With the flow of hydrate particles in a curved pipe as the object of study, the effects of Bend diameter rate and Reynolds number on the velocity distribution, turbulent kinetic energy change, wall shear force, particle motion and pressure drop distribution of the spiral flow carrying hydrate particles were investigated by numerical simulation method. The results show that bend diameter rate is the smaller, and the high speed zone is easier to appear inside the bend. Moreover, the uniformity of the velocity distribution of the fluid flowing through the bend is slower with the smaller the rate of the bend to the diameter. When Re = 20,000, the curve fluctuates more, and the peak speed reaches 4 times that of Re = 10,000. Increasing the Reynolds number of the initial transport can maintain the helical flow strength of the fluid after passing through the bend pipe, so that the flow can obtain higher tangential force. Because the fluid flows into the pipe by spiral flow, the shear force inside the pipe is higher under the combined action of its tangential velocity at the pipe wall and the high speed zone inside the pipe wall. The presence of the twisted tape leads to greater flow resistance, which makes the pressure drop increase at the position of the twisted tape different. At the same position, the Reynolds number is larger, and the pressure drop increases larger, and the Bend diameter rate is larger, and the fluid speed recovers faster, and the velocity is smaller, and the unit pressure drop is smaller, and Unit pressure drop is down 72.9%. The increase of Reynolds number can reduce the resistance coefficient of the Bend part, but the increase of the Bend diameter rate makes the resistance coefficient decrease first and then increase.