DE102008036602B4 - Pipe for transporting flowing media - Google Patents

Abstract

A pipe for transporting flowing media with a multilayer pipe wall, characterized in thatthe multi-layer pipe wall has a wall structure of elastically compliant sublayers, whereby the pipe formed with this wall construction can produce a transition between a laminar flow and a turbulent flow shifted to a higher Reynolds number; wherein the sub-layers of the wall structure are formed of an outer solid skeleton (1), a resilient middle layer (2) and a resilient inner layer (3), the middle layer (2) being made of a soft to liquid material and the inner layer (3) being of a soft material is formed, wherein the middle layer is formed in the form of a covering of a highly viscous, partially liquid or gel-like or a foam or sponge-like material.

Description

The invention relates to a pipe for transporting flowing media according to the preamble of the claim 1 ,

Pipes with a multilayer pipe wall are known. In such pipes, the pipe wall has a layered structure of partly different materials. For example, flexible pre-insulated multi-layer drinking water pipes are known. Multilayer pipes are increasingly being used increasingly in large-capacity aircraft for weight reasons. Safety aspects play a major role here.

The pamphlets DE 19504618 A1 and DE 29502265 U1 describe motor vehicle pipelines with diffusion-tight, frictional and flame-retardant layers. The publication DE 4309829 C2 describes a use of barrier plastics as strength carriers in motor vehicle pipelines.

In DE 694 26 120 T2 discloses a composite hose which is intended to serve as a fuel line and to be resistant to corrosive effects of the fuel and impermeable to fuel vapor as possible. The fuel hose is made up of several layers, the inner layer being made of a THV fluoroplastic and the outer layer being made of a rubber polymer. Between the two layers, a thin binder layer of a HFC fluoropolymer is formed.

The publication DE 928 333 B discloses an elastic, corrosion-resistant and closed conduit and receiving tube. Subject of this document is a pipe assembly of a flexible carrier or reinforcements and arranged thereon plastic corrosion protection compounds, wherein the structure thus formed can be wound into a tube. The structure thus formed forms an at least partially interpenetrating composite of different components that complement each other in their properties.

The AT 287 419 B discloses a multilayer, in particular three-layer, tube and a method for its production. The subject of this document is a pipe structure which is optimized with regard to the acting overlap loads and also should be easy to set up. It is taught in a radial direction elastic tube structure of base layer and filling layer. The filling layer is formed from a granular material.

DE 1 456 964 teaches a method and apparatus for transporting sludges. In this case, a rigid tube wall is disclosed, which has a helically extending rib in the interior. The rib causes a helical flow of slurries on the pipe inner wall and thus counteract blockages by generating mixing processes in the transported sludges.

The pamphlets DE 102004010340 B4 . DE 29712989 U1 . DE 102004056192 B4 and EP 0360758 B1 describe multi-layer pipes in whose layers fibers, minerals or resins contribute to the stability improvement. The publication DE 19926850 A1 describes pipelines with a multi-layer insulation.

The pamphlets US 3,161,385 and US 3,585,953 describe an optimized multi-layered construction of the pipe wall with respect to moving in fluid media body, such as ships or torpedoes.

The flow of media in a pipe causes pipe friction losses. In order to minimize these pipe friction losses, pipes with a hydraulically smooth inner surface are used in the prior art. These are made of correspondingly smooth materials and / or special manufacturing processes.

In general, during operation of a pipeline or a pipeline network, the energy required to circulate a medium is proportional to the pressure loss occurring throughout the network. The pressure loss is the pressure difference between two measuring points in the pipes, fittings, fittings, etc. This pressure difference has its cause in the friction between the medium and the pipe, which is referred to as pipe friction, as well as in the internal friction of the medium itself.

The size of the pipe friction depends on the type of flow, the flow velocity, the pipe diameter and the roughness of the pipe. The pipe friction losses for a laminar flow differ in a fundamental way from those which occur in a turbulent flow in the pipe.

The boundary between laminar and turbulent flow is described by the so-called Reynolds number Re. The Reynolds number is dependent on the mean flow velocity v of the medium and a characteristic length L and the kinematic viscosity of the flowing medium v. For pipe flows L corresponds to the clear diameter D of the pipe. Empirically it turns out that with a value of Re = 2000 the laminar flow in the tube changes into the turbulent flow. These settles particularly fast within valves and branches.

In the transition from laminar to turbulent flow, the friction loss in the pipe increases sharply. For hydrodynamically smooth tubes, this increase is about 60%. By increasing the Reynolds number to a value of Re = 4000, the increase in pipeline losses compared to laminar flow in prior art pipes is already 150% and thus very significant.

The laminar flow of a medium at a low Reynolds number within a tube thus proves to be particularly low loss and effective. A disadvantage of this flow, however, is that the laminar flow is always associated with relatively low flow velocities.

It is therefore the object of the invention to provide a tube with which the boundary between laminar flow and turbulent flow are shifted to higher flow velocities and thus the friction losses and the necessary energy requirements for the flow transport of media can be minimized.

The object is with a pipe for transporting flowing media with the features of the claim 1 solved. The subclaims contain expedient or advantageous embodiments of the pipe according to the invention.

To solve the problem is used on a pipe for transporting media flowing with a multi-layer pipe wall. This tube is inventively characterized in that the multi-layer pipe wall has a wall structure made of elastically resilient sub-layers, which can be generated by the tube formed with this wall construction shifted to a higher Reynolds number transition between a laminar flow and a turbulent flow.

The wall construction formed in this way causes locally increased pressures within the medium to be absorbed and thus reduced by the compression of the partial layers. This prevents the formation of vortices and thus ultimately the transition from laminar to turbulent flow.

Thus, this envelope will only be found at higher flow rates, i.e., compared to a conventional tube. at larger Reynolds numbers, instead. In addition, this design of the wall structure also causes a reduction of vortex formation in the turbulent flowing medium, so that even with a turbulent flow, the friction losses of the flow are significantly minimized.

The sub-layers of the wall structure according to the invention consist of an outer solid framework, a resilient middle layer and a resilient inner layer. The middle layer is formed of a soft to liquid material, while the inner layer is formed of a soft but strong material. Such a design of the layer structure ensures a particularly good local pressure reduction.

The middle layer is in the form of a cover made of a highly viscous, partially liquid or gel-like or a foam or sponge-like material.

The outer solid framework forms a stable outer shell of the tube, the middle layer and the inner layer cause the mentioned reduction of the turbulence occurring in the tube.

It is advantageous if the inner layer has a higher modulus of elasticity than the middle layer.

In a further embodiment, the inner layer contains solid particles. This stabilizes the inner layer on the one hand. On the other hand, it has been found that such a modification of the inner layer can contribute to an improved function of the inner layer.

In a first embodiment, both the inner layer and the middle layer are formed of the same material, wherein the material has a different density depending on the layer.

In a second embodiment, the middle layer and the inner layer are formed of different materials.

The pipe according to the invention will be explained in more detail below with reference to exemplary embodiments. For clarification, the attached serves 1 , This shows an exemplary tube with a multilayer pipe wall in a longitudinal and a cross section.

The outer layer of the multilayer pipe wall is formed by a skeleton 1. In the simplest embodiment, the basic framework is a sufficiently resistant, in the form of a hollow cylinder, sufficiently resilient, if necessary within certain limits elastically bendable and be laid along a curved path body. This can, as required, consist of a metallic material, a concrete, a plastic, but also a glass or a ceramic.

In a further embodiment, the framework consists of a composite material of a reinforcement and a covering material surrounding the reinforcement or a fiber composite.

The basic framework simultaneously forms the outer tube shell with the usual sealing surfaces, connecting pieces, connecting threads and the like connection means. These are designed so that the tube can be easily mounted using the known installation methods.

The basic structure 1 inside a middle layer closes 2 and an inner layer 3 one. The middle class 2 and the inner layer 3 consist of flexible, elastically deformable or soft materials. The layers can either be made of the same material, wherein the density of the inner layer 3 greater than the density of the middle class 2 is. In another embodiment, both layers are made of different materials.

Suitably, a resilient, soft middle layer is combined with an inner layer which is distinguished by a greater modulus of elasticity. As a middle layer in particular coverings of a highly viscous, partially liquid or gel-like material into consideration. If necessary, the liquid or gel is enclosed in a tube-like container.

The middle layer can also consist of a solid material. For this purpose, elastomers, rubber or rubber materials into consideration. Usable are both compact material layers and loosened material structures, such as foams or sponges.

The inner layer 3 consists of a solid, elastic material with a greater modulus of elasticity and / or greater density than the middle layer. For the inner layer in particular elastomers, rubber or rubber materials can be used.

To increase the strength of the inner layer relative to thermal or chemical stresses, a coating is provided in one embodiment. The coating may be in the form of a metallization or a plastic covering.

In a further embodiment, the inner layer has embedded particles. These stabilize the structure of the inner layer.

For an improved adhesion of the middle layer to the skeleton, in an expedient embodiment, formations or roughenings are provided on the inside of the skeleton with which the contact between the middle layer and the skeleton can be made particularly resistant.

A tube with the features described here allows a clear shift of the transition point between laminar and turbulent flow. Experiments have shown that the Reynolds number associated with this envelope can be increased from Re = 2000 to Re = 4000. This means, in particular, that the medium flowing in the tube still shows a laminar flow behavior with a flow velocity doubled in comparison to conventional tubes. This is reflected, in particular, in a friction loss reduced by 40% with this Reynolds number.

Further embodiments will become apparent from the dependent claims or by expert action.

LIST OF REFERENCE NUMBERS

1

backbone

2

middle class

3

inner layer

Claims (5)

Pipe for the transport of flowing media with a multi-layer pipe wall, characterized in that the multi-layer pipe wall has a wall structure made of elastically resilient sub-layers, which can be generated by the tube formed with this wall structure shifted to a higher Reynolds number transition between a laminar flow and a turbulent flow wherein the sublayers of the wall structure are formed of an outer solid skeleton (1), a resilient middle layer (2) and a resilient inner layer (3), the middle layer (2) being made of a soft to liquid material and the inner layer (3) a soft material is formed, wherein the middle layer is formed in the form of a cover of a highly viscous, partially liquid or gel-like or a foam or sponge-like material. Tube after Claim 1 , characterized in that the inner layer (3) has a higher modulus of elasticity compared to the middle layer (2). Pipe according to one of the preceding claims, characterized in that the inner layer (3) contains solid particles. Pipe according to one of the preceding claims, characterized in that the middle layer (2) and the inner layer (3) are formed from a same material, wherein the material has a density which differs from layer to layer. Pipe after one of the Claims 1 to 3 , characterized in that the middle layer (2) and the inner layer (1) are formed of different materials.

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