| Rotating curved pipes are often encountered in engineering applications. With the popularity of rotary machinery in industry, the characteristics of the flow in the controlling pipe system, the transporting pipe system, and the cooling pipe system are the main factors to improve the efficiencies of the rotary machinery, consequently, fluid flow in rotating pipes has become one of the urgent problems in engineering and one of the challenging research fields in fluid mechanics. On the other hand, this flow is a typical non-linear model and there exists complicated secondary flow on the cross-section, also, a bifurcation will appear on some conditions. This study is signality in theory and has a broad application future.In this dissertation, researches on the flow in curved pipes of the last century are firstly reviewed and then a flow model in a rotating helical pipe with multi-parameters is introduced. Employing perturbation method and numerical simulation, we study the flow in rotating helical pipes including different rotations, different cross sections (circular, elliptical, annular and square cross section), and different geometrical structures. We analyze the effects of the flow parameters and the geometrical parameters on the axial flow, the secondary flow and the friction. We also study the bifurcation solutions of the flow in rotating curved square ducts.The following results are obtained: (1) The flow in rotating helical pipes are affected by Dean number, curvature, torsion (or Germano number), the ratio of the Coriolis force to the centrifugal force F number (or Rossby number) and the geometry of the cross section. (2) With F varying, there exists a number Fr which is about -1 (Curvature, torsion and Dean number have little influence on Fr), when F > Fr , the maximum of the axial velocity is near the outside bent and the friction factor ratio increases with F increasing; when F < Fr, the maximum is near the inner side bent and the ratio increases with F decreasing; when F = Fr, the distributions of the axial velocity are similar to those of Poiseuille flow and the friction ratio is about 1. (3) When F is about Fr, the secondary flow reaches its weakest intensity, but has a most complicated structure. For co-rotation and counter-rotation in which the centrifugal force dominates the flow, the secondary flow in a rotating helical pipe has the same direction with that in a stationary one. Forcounter-rotation in which the Coriolis force dominates the flow, the secondary flow has the opposite directions to that in a stationary one. (4) When |F| is very large orRossby number is very small, the Taloy-Proudman phenomenon appears and the flow is symmetry left and right. (5) As torsion is increased, the anticlockwise secondary vortexes and the negative area of the stream function increase; the axial velocity moves anticlockwise (annular pipe) or clockwise (circular pipe); the friction factor ratio finally reaches the value about 1. (6) As Dean number is increased, the secondary flow firstly becomes symmetry and then the anticlockwise vortexes are enlarged, the contours of axial velocity and the stream function become symmetry, the secondary flow is intensified and the friction factor ratio increases. (7) The cross-section has significant effects on the secondary flow. When F is about Fr, for curved pipes, the secondary flow appears eight vortexes for annular cross section and four for circular and four or six for elliptical; for helical pipe, the secondary flow appears as a loop flow for annular and circular cross section, and a saddle flow for elliptical cross section. (8) Six branches of the flow in a rotating square duct are obtained. The limited points of every branch are different for different Dean number. An eight-vortex phenomenon is also found.Comparisons are made between the results of this study and the valuable results of the other authors, all the results are all in good agreements.The innovation points of this study are that we firstly analyze the flow in rotating helical pipe an...
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