圆形截面双扭管内流动稳定性和均匀性评估

For the poor flow stability and uniformity problem of double elbow pipes with circular cross section in industrial water pipeline, based on the energy gradient theory, a numerical simulation method is used to study the influencing rules of three different arrangement modes of the double elbow pipe at angles 0°, 90° and 180° on the flow stability and uniformity when Reynolds number ranges from 6×10⁵ to 1.2×10⁶. The results show that under the same Reynolds number condition, the velocity uniformity of 180° double elbow pipe is the best among the three arrangement schemes within 12D downstream length, followed by 0° double elbow pipe, and 90° double elbow pipe is the worst, while the results of the pressure uniformity are just the opposite. The resultant force at the downstream bend of 90° double elbow pipe has larger components in circumferential and radial directions, resulting in strong secondary flow, while its swirling angle is the largest among the three arrangements. At the downstream 45D location of double elbow pipe with 90°, the swirling angle is about 10°, so a longer straight distance is needed to meet the requirements of flowmeter installation. When the Reynolds number is in the range of 6×10⁵ to 1.2×10⁶, the stability of flow and the pressure uniformity decrease with the increase of Reynolds number, but the corresponding velocity uniformity increases.