The Rotation Curve In The Pipeline For The Unsteady Flow

The fluid flow in the curved pipes is a basic problem in the fluid mechanics, too. As a typical physical model, the study of the fluid flow in curved pipes is through out the history of fluid mechanics. The study on the rotating curved pipes not only has theoretics ignificance, but also can be applied toengineering. The content of the paper is apart of the itern of natural and scientific fund of nation-the study on the flow structure and heat transfer in a rotating curved pipe.In this paper, the characteristics of the unsteady flow in arotating curved circular pipe are considered. In the paper we use theperturbation method and numerical methods to calculate. First, arotating helical polar coordinate system and a rotating helical rightangle coordinate system will be constitute in the curved pipe.Second, we present the control equations using tension analysis inthe two coordinate systems. The unsteady oscillatory flow in theplanar curved pipe is studied by bi-parameter perturbation method.Unsteady seasonal flow in the rotating helical pipe and unsteadyintermittent flow in a rotating curved pipe are studied using thenumerical method. The movements of the axial velocity distributions,the secondary flow structure and the wall friction stress under thedifferent parameters are investigated in detail. The results reveal thatthe unsteady flow is mainly effected by the following parameters: the curvature, the torsion, the force ratio in a cycle(the ratio of Coriolis force to centrifugal force in the cycle) , the Dean numbers, Germano numbers, Rossby numbers, Womersley numbers and other parameters.The second order perturbation results of the unsteady low-frequency oscillatory flow in a helical circular pipe, the numerical results of the unsteady seasonal flow in the rotating helical pipe and unsteady intermittent flow in a rotating curved pipe were obtained in this paper. Furthermore, the results are compared with some published data available in the open literature, excellent agreement has been obtained for all cases, and the methods are proved correct.