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为了考虑实际流体流速非均匀分布对输流管道振动和稳定性的影响,对目前广泛采用的基于理想流体模型的输流管道运动方程进行了修正。对圆管层流,由抛物线分布律得到的离心力项流态修正系数为1.333;对圆管紊流,由指数律和对数律得到基本一致的结果:流态修正系数随Reynolds数的增大而减小,在Re=103—105范围内,流态修正系数为1.018—1.053。与理想流体情况相比,层流和紊流流态下管道的临界流速均有所下降。发散失稳临界流速降低比率分别为13.4%和0.9%—2.5%。流态对颤振失稳临界流速的影响更大,层流下的降低比率可达36%。通过引入等效流速和等效质量2个新概念,可将不同流态下的输流管道问题用理想流体流动下的运动方程进行求解。
In order to consider the effect of the non-uniform distribution of actual fluid velocity on the vibration and stability of the pipe, the widely used flow equations of the pipe based on the ideal fluid model are modified. For the laminar flow in a circular tube, the centrifugal force correction coefficient obtained from the parabolic distribution law is 1.333. For the circular tube turbulence, the result of the exponential law and the logarithmic law is basically the same. The correction coefficient of the fluid state increases with the Reynolds number But decreases in the range of Re = 103-105, and the flow modification coefficient is 1.018-1.053. Compared with the ideal fluid, the critical flow velocity of the pipeline decreases in both laminar and turbulent flow regimes. The critical rates of divergence instability are reduced by 13.4% and 0.9% -2.5%, respectively. The effect of flow regime on the critical flutter instability is greater, with a reduction of up to 36% under laminar flow. By introducing two new concepts of equivalent flow rate and equivalent mass, the flow field under different flow regimes can be solved by the equation of motion under ideal fluid flow.