THE FLOW IN ROTATING CURVED CIRCULAR PIPE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｂｅｈａｖｉｏｒｏｆｔｈｅｆｌｕｉｄｉｎａｒｏｔａｔｉｎｇｃｕｒｖｅｄｐｉｐｅｉｓａｆｕｎｄａｍｅｎｔａｌａｎｄｍｕｃｈ ｓｔｕｄｉｅｄｐｒｏｂｌｅｍ .Ｔｈｅｒｅａｒｅｍａｎｙｅｎｇｉｎｅｅｒｉｎｇａｐｐｌｉｃａｔｉｏｎｓｏｆｔｈｉｓｒｏｔａｔｉｎｇｓｙｓｔｅｍ ,ｓｕｃｈａｓｇａｓｔｕｒ ｂｉｎｅｓ ,ｅｌｅｃｔｒｉｃｇｅｎｅｒａｔｏｒｓａｎｄｅｌｅｃｔｒｉｃｍｏｔｏｒｓ.Ｔｈｅｓｙｓｔｅｍｃａｎａｌｓｏｂｅｆｏｕｎｄｉｎｓｅｐａｒａｔｉｏｎｐｒｏｃｅｓｓ.Ｉｔｉｓ…     

STABILITY IN THE CIRCULAR PIPE FLOW OF FIBER SUSPENSIONS

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｏｗｏｆｆｉｂｅｒｓｕｓｐｅｎｓｉｏｎｓｉｓｖｅｒｙｃｏｍｍｏｎｉｎｍａｎｙｆｉｅｌｄｓｏｆｉｎｄｕｓｔｒｉａｌｐｒｏｄｕｃｔｉｏｎ ,ｓｕｃｈａｓｃｈｅｍｉｃａｌｅｎｇｉｎｅｅｒｉｎｇ,ｍａｔｅｒｉａｌａｎｄｆｏｏｄｐｒｏｃｅｓｓｉｎｇ .Ｉｔｉｓｎｅｃ ｅｓｓａｒｙｔｏｒｅｓｅａｒｃｈｔｈｅｃｈａｒａｃｔｅｒｉｓｔｉｃｓｏｆｆｌｏｗｏｆｆｉｂｅｒｓｕｓｐｅｎｓｉｏｎｓ,ｏｎｅｏｆｗｈｉｃｈｉｓｔｈｅｆｌｏｗｓｔａｂｉｌｉｔｙ .Ｆｉｂｅｒａｄｄｉｔｉｖｅｓｍａｙ…     

LAMINAR FLUID FLOW IN HELICAL ELLIPTICAL PIPE

1.　INTRODUCTIONHelicalductsappearinvariousindustrialapplictionsandadetailedknowledgeofthefluidflowbehaviorisimportantforpredictingthepressuredropandheatandmasstransfercharacteristics.Experimentalandtheoreticalanalysishaveattestedthatthesecondaryflowappearsthenormalcross-sectionbecauseofthecurvature.Thissecondaryflowisveryfaintcomparedwiththeaxialflow,butitcausestheincreaseofheattransfer.Thestudyonthisflowbeganin1927withthepaperofDean[1],inwhichtheflowintoroidalsystemwasstudied.Sincethen…     

TRANSPORT EFFICIENCY OF THE SPIRAL FLOW IN CIRCULAR PIPE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＧｒａｉｎｍａｔｅｒｉａｌｔｒａｎｓｐｏｒｔｉｎｐｉｐｅｆｌｏｗｈａｓａｈｉｓｔｏｒｙｏｆｍｏｒｅｔｈａｎｏｎｅｈｕｎｄｒｅｄｙｅａｒｓ .Ｉｎｒｅｃｅｎｔｓｅｖｅｒａｌｄｅｃａｄｅｓｔｈｅｔｅｃｈｎｏｌｏｇｙｈａｓｂｅｅｎｄｅｖｅｌｏｐｉｎｇｖｅｒｙｒａｐｉｄ ｌｙ .Ｔｈｅｒｅａｒｅｍｏｒｅｔｈａｎ 2 6ｓｏｒｔｓｏｆｍａｔｅｒｉａｌｓｓｕｃｈａｓｃｏａｌ,ｓａｎｄ ,ｃｏｎｃｅｎｔｒａｔｅ ,ｔａｉｌｉｎｇｓａｎｄｏｔｈｅｒｇｒａｉｎｍａｔｅ ｒｉａｌｓａｒｅｔｒａｎｓｐｏ…     

PERTURBATION SOLUTION OF SECONDARY FLOW OF POWER-LAW FLUID IN HELICAL PIPES WITH CIRCULAR CROSS-SECTION

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｆｌｏｗｉｎｈｅｌｉｃａｌｐｉｐｅｓｉｓｖｅｒｙｃｏｍｐｌｅｘａｎｄｖｅｒｙｉｍｐｏｒｔａｎｔｉｎｂｏｔｈｔｈｅｃｈｅｍｉｃａｌｉｎｄｕｓｔｒｙａｎｄｔｈｅｐｅｔｒｏｌｅｕｍｉｎｄｕｓｔｒｙ .ＡｌｏｔｏｆｗｏｒｋｈａｓｂｅｅｎｄｏｎｅｂｙＭｕｒａｔａｅｔａｌ.[1] ,Ｗａｎｇ[2 ] ,Ｇｅｒｍａｎｏ[3 ,4 ] ,Ｋａｏ[5] ,Ｔｕｔｔｌｅ[6] ,ａｎｄＬｉｕ[7] .ＢｕｔｔｈｅｙｏｎｌｙｓｔｕｄｉｅｄｔｈｅＮｅｗｔｏｎｉａｎｆｌｕｉｄｉｎｈｅｌｉｃａｌｐｉｐｅｓ .Ｔｈｅｒｅｉｓｎｏ…     

LAMINAR DEVELOPING FLOW IN THE ENTRANCE REGION OF ROTATING CURVED PIPES

1. INTRODUCTION The flow in rotating curved pipes with a constant circular cross-section have found wide applications in heat exchangers, piping systems, electric motors, chemical reactors and many other engineering systems. One of the principle features …     

NUMERICAL SIMULATION OF TURBULENT FLOW CHARACTERISTICS IN A CURVED PIPE WITH A BAFFLE

A numerical study on the characteristics of developing turbulent flow in a curved pipe with a baffle was carried out in body-fitted coordinates with the k-ε model turbulence. A curved duct of square cross-section was examined first, and the results agree very well with the experimental data. Then two kinds of pipes, a normal curved pipe and that with a baffle were studied. The computational results are presented and compared with each other to illustrate the changes of the flow after adding the baffle. The longitudinal velocity in the pipe with a baffle was characterized by outer velocity bigger than the inner one. The secondary flow was characterized by four-vortex structure with the intensity reduced, which results in the equability of the flow field of the cross-section compared with that without a baffle, and has much more significant meaning in engineering.     

THE PERTURBATION SOLUTIONS OF THE FLOW IN A ROTATING CURVED ANNULAR PIPE

1 .　ＩＮＴＲＯＤＵＣＴＩＯＮＡｓａｎｉｎｔｅｒｅｓｔｉｎｇｆｕｎｄａｍｅｎｔａｌｐｒｏｂｌｅｍｉｎｆｌｕｉｄｍｅｃｈｎｉｃｓ,ｔｈｅｆｌｏｗｓｉｎｒｏｔａｔｉｎｇｃｕｒｖｅｄ ｐｉｐｅｓｗｉｔｈｃｉｒｃｕｌａｒｏｒｒｅｃｔａｎｇｕｌａｒｃｒｏｓｓ ｓｅｃｔｉｏｎｓｈａｖｅｂｅｅｎｓｔｕｄｉｅｄｂｙｎｕｍｅｒｏｕｓａｕｔｈｏｒｓ .Ｌｕｄｗｉｅｇ[1] ｉｓｔｈｅｆｉｒｓｔｒｅｓｅａｒｃｈｅｒｔｏａｎａｌｙｚｅｔｈｅｆｌｏｗｉｎａｒｏｔａｔｉｎｇｃｕｒｖｅｄｒｅｃｔａｎｇｕｌａｒｄｕｃｔａｎｄｄｅｖｅｌｏ…     

TURBULENT BOUNDARY LAYER DEVELOPMENT IN THE ENTRANCE REGION OF A SMOOTH ROUND PIPE

The study of the turbulent boundary layer along a smooth round pipe is of greatsignificance both in practice and in theory.In this paper,the formulae for calculating the tur-bulent boundary layer thickness are obtained by solving the momentum integral equation of theboundary layer in which the assumptions of the logarithmic law and exponential law of velocitydistribution are adopted.The methods for calculating the mean flow velocity in the developingregion of turbulent boundary layer in a round pipe are proposed.The relation between the expo-nent n and the factor μ·δ/ν is studied and a formula for calculating the exponent n is obtained.     

MEASUREMENT OF HYDRODYNAMIC FORCES ACTING ON A CIRCULAR CYLINDER NEAR A PLANE BOUNDARY IN STEADY FLOW

In this paper,the characteristics of hydrodyna(?) forces on a circular cylindernear a plane boundary have been studied experimentally in w(?) tunnels.The drag coefficientC_D,mean lift coefficient C_(L0),T.m.s.lift coefficient C_(L Tms),maximum lift coefficient C_(L max) andfluctuating lift coefficients C'_(L Tms),C'_(L max),and lift(vortex shedding)frequency have been mea-sured on condition that the thickness of plane boundary layer,δ,was 0.1D(D is the diameter ofthe cylinder)at the station of the centre of the cylinder,and Reynolds number,Re,varied from4.5×10~3 to 1.76×10~5.The regularity of the change of these coefficients with Re and gap ratioG/D is found.The measurement of the lift frequency shows that a strong non-linear coupling ac-tion appears when the gap ratio between the circular cylinder and plane,G/D,reaches 0.5,andthe shedding of regular vortex is suppressed when G/D=0.2.     

THE METHOD OF SEMI-FALSE TRANSIENT FOR COMPUTING THE FLOW INTO POROUS MEDIUM IN THE CIRCULAR PIPE

The method of semi-false transient was used to numerically compute the incompressible steady flow into the porous medium n this paper. The fundamental equations were established and numerically solved in the united flow field,which included the space region and the porous region. The non-equidistant non-orthogonal semi-staggered mesh system was used in the method of semi-false transient.The computational results of two problems concerning the flow into porous medium from space region,in which there was the backward flow besides main flow, were obtained adn discussed. It is seen from the results that the backward flow is generally not present in the porous medium as the osmotic resistance is very large.     

NUMERICAL SIMULATION OF AN OSCILLATING FLOW PAST A CIRCULAR CYLINDER IN THE VICINITY OF A PLANE WALL

Oscillating flow around a circular cylinder in the vicinity of a plane wall was investigated by solving the two-dimensional incompressible Navier-Stokes equations with a finite element Galarkin residual method. The effect of the gap G/D between the cylinder surface and the wall on the flow behavior was studied. For the case of G/D 〈 0.25, the periodicity in the flow is attributed to both the outer shear layer instability and the oscillating frequency. As G/D 〉 0.25, vortex shedding occurs and the periodicity in the flow is mainly due to the competition of the oscillating frcqucncy and the vortex shedding frequency from an isolated stationary cylinder.     

A STUDY ON THE FLOW IN HELICAL ELLIPTICAL PIPES WITH GALERKIN METHOD

1. INTRODUCTIONSince the initial work by Dean[1 ,2],the flowand heat transfer through curvilinear pipes have at-tracted more and more attention not only becauseof their practical i mportance in various industrialapplications ,but also because of physicall…     

EFFECT OF NON-SPHERICAL PARTICLES ON THE FLUID TURBULENCE IN A PARTICULATE PIPE FLOW

In the non-spherical particulate turbulent flows,a set of new fluid fluctuating velocity equations with the nonspherical particle source term were derived, then a new method,which treats the slowly varying functions and rapidly varying functions separately, was proposed to solve the equations, and finally the turbulent intensity and the Reynolds stress of the fluid were obtained by calculating the fluctuating velocity statistically. The equations and method were used to a particulate turbulent pipe flow. The results show that the turbulent intensity and the Reynolds stress are decreased almost inverse proportionally to the fluctuating velocity ratio of particle to fluid. Nonspherical particles have a greater suppressing effect on the turbulence than the spherical particles. The particles with short relaxation time reduce the turbulence intensity of fluid, while the particles with long relaxation time increase the turbulence intensity of fluid. For fixed particle and fluid, the small particles suppress the turbulence and the large particles increase the turbulence.     

NUMERICAL ANALYSIS OF THE FLUID FLOW IN A ROTATING CURVED ELLIPTICAL PIPE

A numerical study was conducted for the fully developed laminar flow in rotating curved elliptical pipe. Due to the rotation, the Coriolis force can also contribute to the secondary flow. The interaction of rotation and curvature complicates the flow characteristics. The boundary fitted coordinate was adopted to study the flow characteristic in the rotating systems. The effects of rotation on the flow transition were studied in detail. The generation and mergence of vortices in rotating curved elliptical pipes were also captured for the first time. The simulation results show that the flow for the case of large aspect ratio of the cross-section is more likely to be unstable than that for smaller one.     

ON THE MECHANISM OF DRAG REDUCTION IN HIGH CONCENTRATION NON-HOMOGENEOUS PIPE FLOW

In this paper a method for calculating the resistance force in high concentrationnon-homogeneous pipe flow is suggested.Comparing with experiment,it is shown that the theo-retical results are in good agreement with the experimental ones.     

FLOW AND HEAT TRANSFER OF OLDROYD-B FLUIDS IN A ROTATING CURVED PIPE

The flow and convected heat transfer of the Oldroyd-B fluids in a rotating curved pipe with circular cross-section were investigated by employing a perturbation method. A perturbation solution up to the second order was obtained for a small curvature ratio, κ. The variations of axial velocity distribution and secondary flow structure with F, Re and We were discussed in detail in order to investigate the combined effects of the three parameters on flow structure. The combined effects of the Coriolis force, inertia force and elastic force on the temperature distribution were also analyzed, which are greater than the adding independent effects of the three forces. The variations of the flow rate and Nusselt number with the rotation, inertia and elasticity were examined as well. The results show the characteristics of the heat and mass transfer of the Oldroyd-B fluids in a rotating curved pipe.     

COMPREHENSIVE STUDY OF COMBINING FLOW CONDITIONS AT PIPE JUNCTIONS

ＣＯＭＰＲＥＨＥＮＳＩＶＥＳＴＵＤＹＯＦＣＯＭＢＩＮＩＮＧＦＬＯＷＣＯＮＤＩＴＩＯＮＳＡＴＰＩＰＥＪＵＮＣＴＩＯＮＳ￥ＭａｏＺｅ－ｙｕ（ＨｙｄｒａｕｌｉｃｓＧｒｏｕｐ，ＤｅｐａｒｔｍｅｎｔＯｆＨｙｄｒａｕｌｉｃＥｎｇｉｎｅｅｒｉｎｇ，Ｔｓｉｎｇｈｕａ...     

BASIC HYDRODYNAMICS CHARACTERISTICS OF CAVITY SPIRAL FLOW IN A LARGE SIZE LEVEL PIPE

Based on the observation of a model test and in combination with some theoretical analysis, the researches of some basic hydrodynamics characteristics of cavity spiral flow in a large size level pipe with a shaft-inlet is presented in the paper, which include the basic flow pattern, formation condition of the cavity spiral flow, discharge Q, cavity diameter d0, wall pressure coefficient Cpw, velocity distribution, total energy dissipation rate η etc. The results show that the basic flow patterns can be divided into three zones according to the variations in amount of ventilation Ф, cavity diameter d0 and gas pressure p0 within cavity spiral flow when the upstream and downstream water level changes and that the basic hydrodynamics characteristics change with the flow pattern and have the different behaviour.     

UNSTEADY INTERMITTENT FLOW IN A ROTATING CURVED PIPE

The effects of rotation and intermittent frequency on the flow transition of secondary flow and. main flow were examined in detail. Certain hitherto unknown flow patterns were found. ,‘% numerical study was performed to study the characteristics of unsteady intermittent flow in a rorating curved pipe. Due to the rotation, both the Coriolis for ceand the centrifugal force could contribute to the unsteady intermittent flow and some complicated phenomena can be found. The results indicate that the unsteady intermittent floware mainly characterized by five parameters: the Dean number Dn, the curvature κ. the maximal force ratio F (of the Coriolis force to the centrifugal force in a cycle), the intermittent frequency parameter r/(the ratio of a pulslating time to the cycle period), and the Womersley number a. Present works shows the natures of the unsteady intermittent flow in a rotating curved pipe.