阅读说明：本技术 一种封闭旁支管道的流体控制单元 (Fluid control unit for sealing side branch pipeline ) 是由 李玩幽 王曦 率志君 殷文慧 于涛 曹宏博 简洁 于 2021-09-01 设计创作，主要内容包括：本发明的目的在于提供一种封闭旁支管道的流体控制单元,包括主管道、旁支管道,主管道的两端分别为管道入口和管道出口,旁支管道与主管道直接相连,旁支管道与主管道还通过引流管相连,引流管一端连接主管道的上游区域,另一端连接旁支管道。本发明引流管结构简单,加工方便,方案可行性强；结构尺寸较小,不占用太多空间,并且不影响旁支管道内本身的结构空间；可以实现共振频率解耦,改变漩涡脱落频率,从根源上抑制流致声共振,为处理类似封闭支管振动问题提供借鉴。(The invention aims to provide a fluid control unit for sealing a side branch pipeline, which comprises a main pipeline and the side branch pipeline, wherein the two ends of the main pipeline are respectively provided with a pipeline inlet and a pipeline outlet, the side branch pipeline is directly connected with the main pipeline, the side branch pipeline is also connected with the main pipeline through a drainage pipe, one end of the drainage pipe is connected with the upstream area of the main pipeline, and the other end of the drainage pipe is connected with the side branch pipeline. The drainage tube is simple in structure, convenient to process and strong in scheme feasibility; the structure size is small, too much space is not occupied, and the structure space in the side branch pipeline is not influenced; the decoupling of resonance frequency can be realized, vortex shedding frequency is changed, flow induced acoustic resonance is fundamentally inhibited, and reference is provided for processing the vibration problem of similar closed branch pipes.)

1. A fluid control unit for closing a bypass conduit, comprising: including trunk line, side branch pipeline, the both ends of trunk line are pipeline entry and pipeline export respectively, and side branch pipeline directly links to each other with the trunk line, and side branch pipeline still passes through the drainage tube with the trunk line and links to each other, and the upper reaches region of trunk line is connected to drainage tube one end, and side branch pipeline is connected to the other end.

2. A fluid control unit for closing a bypass conduit as defined in claim 1, wherein: the position where the drainage tube is connected with the main pipeline is positioned above the rotating center of the vortex group in the side branch pipeline.

3. A fluid control unit for closing a bypass conduit according to claim 1 or 2, wherein: the drainage tube structure adopts the same type of pipeline model as the bypass pipeline, the wall thickness of the pipeline is the same, the width of the drainage tube is the same as that of the bypass pipeline, and the cross section of the drainage tube is 1/4 round.

Technical Field

The invention relates to a pipeline structure, in particular to a closed branch pipe structure.

Background

The flowing medium in a primary loop main pipeline of a nuclear power system is usually high-temperature and high-pressure fluid, a pressure relief pipeline is usually arranged at a specific position of a main pipeline in order to ensure the safe operation of the nuclear power system, one section of the pressure relief pipeline is generally connected with the main pipeline, and the other end of the pressure relief pipeline is closed under the conventional condition, so that a special structure of a closed bypass pipeline is formed.

The flow acoustic resonance is the interaction result of a sound field and an unstable flow field, and when fluid in a main pipeline flows through a T-shaped filler neck of a branch pipe, vortex shedding occurs and pressure pulsation is generated; the pressure pulsation is used as a sound source to generate pressure waves to be transmitted to the tail end of the branch pipe, the pressure waves are reflected by the wall surface of the tail end of the branch pipe section and then interact with incident waves in the branch pipe to form standing waves, and the frequency of the standing waves is coupled with the shedding frequency of the vortex, so that the pressure pulsation is amplified. When the natural frequency of the pipe is close to the 2 modal frequencies, pipe vibration is excited, which is an external manifestation of flow induced acoustic resonance and is the result of the combined action of "flow-acoustic-solid" resonance.

In a nuclear power system, the safety of related parts of a nuclear reactor is of great importance, and the phenomenon of flow-induced acoustic resonance can cause abnormal vibration of a pipeline and damage parts such as a safety relief valve and the pipeline on a main pipeline. Therefore, in the engineering practice, the phenomenon of flow-induced acoustic resonance is inhibited, and the method has important significance for improving the safe service life and the economic benefit of equipment.

When fluid flows through a specific structure of a closed side branch pipeline, vortex can be generated and periodically falls off, when fluid excitation generated by the falling frequency of the vortex is close to the frequency of an acoustic mode, a frequency locking phenomenon is generated, pressure waves are amplified to form acoustic resonance, and when the frequency of the acoustic resonance is coincident with the structural frequency of a pipeline, the pipeline can be excited to vibrate violently.

The commonly used method for avoiding the flow acoustic resonance is as follows: (1) and introducing a section of branch pipe at one side of the branch pipe, and adjusting the acoustic trapping mode of the side branch pipe to enable the side branch pipe to be avoided from the flow field frequency. (2) And performing flow field geometric optimization (such as increasing chamfer radius) at the intersection position of the bypass pipeline and the main pipeline, and adjusting the vortex shedding frequency of the flow field to avoid the vortex shedding frequency from the acoustic trapping mode. (3) Insert elements are designed in the branch ducts to disturb the shear layer in the duct, as in patent US 4867190. However, the scheme is generally high in manufacturing cost, a long branch pipe section is needed to obviously change the acoustic mode, and the scheme II can reduce the amplitude of flow acoustic resonance to a certain extent, but generally has limited influence on frequency. The change of the frequency of the flow field is obvious, but the function of the branch pipeline in the practical engineering application of the nuclear power system is mainly to discharge the pressure in the main pipeline in an emergency, so that the cross-sectional area of the branch pipeline is limited to a certain extent, and the practical application is less.

Disclosure of Invention

The invention aims to provide a fluid control unit for closing a side branch pipeline, which is used for inhibiting flow-induced acoustic resonance from the angle that the turbulence degree of a flow field of the side branch pipeline is increased, the development process of vortex is influenced, and the excitation frequency of the flow field is deviated.

The purpose of the invention is realized as follows:

the invention relates to a fluid control unit for sealing a side branch pipeline, which is characterized in that: including trunk line, side branch pipeline, the both ends of trunk line are pipeline entry and pipeline export respectively, and side branch pipeline directly links to each other with the trunk line, and side branch pipeline still passes through the drainage tube with the trunk line and links to each other, and the upper reaches region of trunk line is connected to drainage tube one end, and side branch pipeline is connected to the other end.

The present invention may further comprise:

1. the position where the drainage tube is connected with the main pipeline is positioned above the rotating center of the vortex group in the side branch pipeline.

2. The drainage tube structure adopts the same type of pipeline model as the bypass pipeline, the wall thickness of the pipeline is the same, the width of the drainage tube is the same as that of the bypass pipeline, and the cross section of the drainage tube is 1/4 round.

The invention has the advantages that:

1. the drainage tube has simple structure, convenient processing and strong feasibility of the scheme;

2. the structure size is small, too much space is not occupied, and the structure space in the side branch pipeline is not influenced;

3. the decoupling of resonance frequency can be realized, vortex shedding frequency is changed, flow induced acoustic resonance is fundamentally inhibited, and reference is provided for processing the vibration problem of similar closed branch pipes.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic cross-sectional view of the present invention;

FIG. 3 is a diagram of the numerical simulation results of the present invention.

Detailed Description

The invention will now be described in more detail by way of example with reference to the accompanying drawings in which:

with reference to fig. 1-3, the invention avoids the flow acoustic resonance frequency to a certain extent, and reduces the excitation amplitude of the excitation source, thereby avoiding the problem of exciting abnormal vibration of the closed bypass pipeline. Therefore, the invention provides a fluid passive control unit, which is a novel closed branch pipe which is added with a drainage pipe structure and communicates the front edge of a main pipe with the flow field of a side branch pipe on the basis of a conventional closed branch pipe structure. The drainage tube is through introducing branch pipe with some fluid from the trunk line, strikes the vortex structure that itself formed in the pipeline to destroy the big vortex structure in the trunk line, reduce the velocity of flow of vortex in the pipeline, thereby aggravate the shear layer instability of trunk line and branch pipe, accelerate the swirl and drop, finally make swirl frequency of dropping and acoustic cavity natural frequency avoid.

The closed side branch pipeline comprises a pipeline inlet and outlet, a main pipeline and a side branch pipeline structure, and the side branch pipeline is directly connected with the straight pipeline. The drainage tube provided by the invention is used for secondary connection of a main pipeline and a side branch pipeline, the drainage tube structure adopts the same type of pipeline model as the side branch pipeline, the wall thickness of the pipeline is the same, the width of the drainage tube structure is consistent with that of the side branch pipeline, the drainage tube structure is an 1/4 round structure, one end of the drainage tube structure is connected with the main pipeline and passes through the upstream area of the side branch pipeline, the other end of the drainage tube structure is communicated with the side branch pipeline, the size of the drainage tube structure has no specific requirement, but the position connected with the main pipeline is required to be positioned above the rotating center of a vortex group in the side branch pipeline, and the specific size is based on practical problems.

The example provides a closed side branch pipeline with a drainage pipe structure, which consists of a pipeline inlet 1, a pipeline outlet 2, a main pipeline 3, a side branch pipeline 4 and a drainage pipe structure 5, and is shown in figure 1. The branch pipe of the pipeline is partially closed, no fluid flows inside the pipeline, the air in the pipeline is sufficiently exhausted, the condition that the air cavity contracts and expands to cause vibration does not exist, and the fluid flow excitation does not exist in the branch pipe basically. A chamfer is arranged at the junction of the branch pipe section and the front edge of the main pipe, and the specific structure is shown in a pipe section flow field diagram of figure 2. Fig. 3 is an example of a numerical simulation result of adding a drainage pipeline and a normal bypass pipeline, and the result shows that the vortex shedding frequency of a flow field is obviously deviated.

In the working process of the closed branch pipe, fluid flows in from an inlet, flows along a main pipeline, and flows to a drainage pipe structure area, partial fluid medium flows into a side branch pipe through a drainage pipe, at the moment, the flow velocity of the fluid in the main pipeline is high, a high-speed gradient shear layer can be formed at the junction of the branch pipe and the main pipeline, due to the instability of the shear layer, the fluid at the position of a tee joint can form a vortex at the junction and finally falls off after a series of development, the vortex falling frequency is close to the acoustic modal frequency of the pipeline, the flow acoustic resonance is caused by the modulation effect, the abnormal vibration of the pipeline is caused, the closed branch pipe of the drainage pipe structure is increased, partial fluid flows into the branch pipe through the drainage pipe structure, the large vortex in the branch pipe collides with each other at the outlet of the drainage pipe, the rotating speed of the vortex group in the branch pipe is changed, the speed gradient at the junction is reduced, the instability of a flow field is reduced, and the falling speed of the vortex group is reduced, and the flow field excitation frequency is changed, so that flow acoustic resonance is inhibited, and the vibration characteristic of the pipeline is optimized.