A device for reducing the pressure peak of water hammer effect in a pipeline

Abstract

The application belongs to the technical field of water hammer effect reduction equipment, and specifically relates to a device for reducing water hammer effect pressure peak of a pipeline. The device comprises an inlet connecting pipeline, a left side of the inlet connecting pipeline being a forward flow inlet and being used for connecting an external main pipeline, an outlet connecting pipeline, a right side of the outlet connecting pipeline being a reverse flow inlet and being used for connecting the external main pipeline, a kettle-shaped body, a left side of the kettle-shaped body being inwardly recessed, an inner diameter of a recessed position being the same as that of the main pipeline, an inner diameter of the kettle-shaped body sequentially decreasing from left to right to be the same as that of the pipeline, and left and right ends of the kettle-shaped body being in communication with the inlet connecting pipeline and the outlet connecting pipeline respectively. The device has simple structure, high compatibility with the original pipeline, high replaceability, no energy consumption in working, and thus low production, use and maintenance costs.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water hammer effect reducing device, and particularly relates to a device for reducing pressure peak of water hammer effect of a pipeline. BACKGROUND

[0002] Water hammer effect, also known as water impact, refers to a phenomenon that, in the process of water conveying, due to sudden closing of a valve, sudden stopping of a water pump, sudden opening and closing of guide vanes, sudden change of load in a pipeline system, etc., sudden change of flow velocity in the pipeline is caused, leading to sharp change of pressure and impact effect on the pipeline wall. When water hammer effect occurs, compression and cavitation appear alternately, pressure pulse propagates in the pipeline in the form of pressure wave, reflects between the walls, and forms oscillation wave. Significant water hammer effect can not only knock down the valve, damage the pipeline, cause the water pump to reverse, and reduce the operation efficiency, but also cause strong vibration and loud noise, and even cause serious damage to the equipment, resulting in major safety production accidents and seriously affecting production and life. In order to reduce water hammer effect, water hammer air valves, check valves, water hammer energy absorption buffers, etc. are often used in engineering, and the structures of these devices are relatively complex, the cost is high, the movable parts are often at risk of fatigue failure, and the single-direction arrangement of these devices will form new stress impact and cause vibration, which is not conducive to popularization and use.

[0003] The device for reducing pressure peak of water hammer effect of a pipeline provided by the application changes the pressure peak by designing a flow structure to block the flow by itself, thereby achieving reduction of water hammer effect. The device has simple structure, low cost, no movable parts inside, no fatigue failure problem, uniform load on the circumference of the pipeline, no new vibration, and is suitable for wide promotion. In addition, the device can be used with original water hammer prevention measures and devices, and also plays a protective role on the latter. SUMMARY

[0004] The application provides a device for reducing pressure peak of water hammer effect of a pipeline, so as to be connected with an existing pipeline through a flange and effectively protect the pipeline when water hammer occurs.

[0005] The application adopts the following technical scheme: a device for reducing pressure peak of water hammer effect of a pipeline, comprising:

[0006] An inlet adapter pipeline, a left side of the inlet adapter pipeline being a forward flow inlet and being used for connecting an external main pipeline;

[0007] An outlet adapter pipeline, a right side of the outlet adapter pipeline being a reverse flow inlet and being used for connecting an external main pipeline;

[0008] A kettle-shaped body, a left side of the kettle-shaped body being recessed inward, an inner diameter of a recessed part being the same as that of the main pipeline, and the inner diameter of the kettle-shaped body decreasing from left to right to be the same as that of the pipeline, and left and right ends of the kettle-shaped body being in communication with the inlet adapter pipeline and the outlet adapter pipeline, respectively.

[0009] In some embodiments, the diameter of the inlet and outlet of the kettle-shaped body is the same and consistent with the diameter of the inlet adapter pipe, the outlet adapter pipe, the external main pipe and the like.

[0010] In some embodiments, the kettle-shaped body is a section of axisymmetric pipe, which is a hollow pipe formed by rotating an axis around the axis of the pipe.

[0011] In some embodiments, the rotation curve on the inner side of the kettle-shaped body comprises:

[0012] a straight segment, which is arranged at an angle with the axis of the pipe, and the ''flat cone'' structure formed by rotating the straight segment around the axis is a diffusion section after the fluid enters from the reverse inlet, and the fluid velocity is reduced and uniform flow is formed on a wider cross section;

[0013] an arc segment, one end of which is tangent to the end of the straight segment, and the other end of which is tangent to the axis of the main flow pipe.

[0014] In some embodiments, the straight segment is at an angle of 15-30° with the axis of the pipe.

[0015] In some embodiments, the arc segment is a section of the Fibonacci spiral, and the curve arc segment is a 90-degree sector arc line determined in two squares with the key parameters a and b of the Fibonacci spiral as the side length, and the curve arc segment connected by the two sector arc lines, a / b=1.61803.

[0016] In some embodiments, the maximum inner diameter D of the kettle-shaped body and the diameter d of the main flow pipe satisfy .

[0017] In some embodiments, the length L of the internal pipe is 10(a+b+R), as shown in Figure 2 , where a is the circumscribed square side length of the arc segment II of the Fibonacci spiral, and b is the circumscribed square side length of the arc segment I of the Fibonacci spiral. As shown in Figure 3-1 , the starting point of the internal pipe length is the tangent point of the arc segment and the main pipe, and the ending point is the joint of the straight segment and the main pipe, R is the radius of the main flow circular pipe, and the length of the internal pipe is L.

[0018] In some embodiments, the device for relieving the pressure peak of the water hammer effect is connected in series in the pipe.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) There are no moving parts in the device, and there are no electric control elements and action mechanisms, and the reliability is high. The device completely relies on its own flow structure to regulate the pressure peak of the reverse flow when the water hammer effect occurs, and does not need external energy to complete the control action;

[0021] (2) The structure is simple, and the compatibility with the original pipeline is strong, the replaceability is strong, and no energy is consumed in work, so that the production, use and maintenance costs are low;

[0022] (3) The device is not used for completely eliminating the water hammer effect, but aims to reduce the pressure peak of the water hammer effect to reduce the impact on the pipeline;

[0023] (4) The device is a circumferential rotating structure, and the circumferential flow and load are uniform, and when water hammer occurs, no new alternating load impact on the pipeline system is generated.

[0024] (5) The device can be used with the original water hammer prevention measures and devices, and also protects the original water hammer prevention measures and devices. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a physical structure detail map of the present application;

[0026] Figure 2 is a key rotating curve diagram inside the kettle-shaped body;

[0027] Figure 3 is a water hammer prevention structure parameter schematic diagram;

[0028] Figure 4 is a water hammer prevention principle flow schematic diagram

[0029] Figure 5 is a water hammer prevention pressure reduction effect diagram;

[0030] Figure 6 is a series water hammer prevention pressure reduction effect diagram;

[0031] Figure 7 is a series water hammer prevention device diagram;

[0032] Figure 8 is a series water hammer prevention reduction effect diagram;

[0033] Figure 9 is a parameter setting principle diagram of the water hammer prevention device;

[0034] In the figure, 1 is a main flow pipeline, 2 is a kettle-shaped body, 101 is a forward flow inlet, 102 is a reverse flow inlet, 201 is a straight line segment, 202 is an arc segment I, 203 is a straight line, 204 is a dotted line frame, and 205 is an arc segment II. DETAILED DESCRIPTION

[0035] In order to make the purposes, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0036] Embodiment one:

[0037] Please refer to Figure 1 , the present application provides a kind of physical structure for mitigating water hammer effect pressure peak, the structure includes a main flow pipeline and a kettle body, the left side of main flow pipeline is positive flow inlet, the right side is reverse flow inlet, kettle body 2 left side is recessed inward, the inner diameter of recessed place is same with main flow pipeline, the inner diameter of kettle is sequentially reduced from left to right to same with pipeline, left and right respectively with pipeline is connected.The outer surface of kettle body is smooth surface, the maximum inner diameter D of kettle body and the diameter d of main flow pipeline need to satisfy . Please refer to Figure 2 , straight line 203 is the axis of main flow pipeline, the complete curve diagram of Fibonacci spiral in dashed line frame 204 is spiral curve drawn according to Fibonacci sequence, it is in the rectangle that square is spliced with Fibonacci number as side, draw a 90 degree sector, the arc line that is connected.Arc segment takes a section of Fibonacci spiral line as the outer contour line of spiral line pipe wall kettle body, in the figure , it meets the golden section ratio, wherein a is the outer tangent square side length of Fibonacci spiral arc segment II 205, b is the outer tangent square side length of Fibonacci spiral arc segment I 202, it meets the numerical characteristics of Fibonacci spiral, compared with other geometric characteristics of convolution curve, the section of curve has very special geometric convolution characteristics and excellent motion continuity, when fluid moves along the section of spiral arc segment, it will produce regular rotation, and has very good effect on water hammer mitigation.Characteristics straight line segment 201 is tangent to the part of Fibonacci spiral line at the position shown in the figure, and the arc line between the tangent point and the starting point of the Fibonacci spiral line is the arc line shape (spiral line pipe wall) along which the kettle body of the structure is recessed inward. Please refer to Figure 3 , the structure needs to be connected into pipeline for use, since most original pipelines are cylindrical, it is easy to connect and match with them, the diameter of pipeline is 2R, and the length of internal pipeline needs to satisfy L=10 (a+b+R), wherein a is the outer tangent square side length of Fibonacci spiral arc segment II 205, b is the outer tangent square side length of Fibonacci spiral arc segment I 202, and R is the radius of main flow cylindrical pipeline. As Figure 4As shown, when the structure is connected to the pipeline, the sudden increase in the inner diameter of the water flow pipeline will not affect the normal flow to the right. When the water hammer effect occurs, the water will flow to the left along the arrow direction of the right side of the kettle-shaped body, and along the arc of the designed Fibonacci spiral to form a vortex, making it easier for water to flow into the main flow area of the pipeline. The water flowing back collides with the water flowing to the left in the main flow area on the right, weakening the reverse flow of water and reducing the speed and pressure of the water flow, effectively releasing the energy of the reverse flow and reducing the impact of the water hammer effect. The design of this structure can effectively mitigate the water hammer effect, and the local structure can be connected to the pipeline in any form, even at any position where water hammer reduction is needed, to produce effective pressure drop and protect the pipeline. Please refer to Figure 5 , Figure 5 The figure shows the comparison of the pressure in the pipeline before and after the structure is connected to the pipeline. The figure is obtained from experimental simulation and numerical simulation. As shown in the figure, the pressure drop effect is obvious after the structure is connected to the pipeline. In the same time, the maximum reduction of the cycle number of the pressure in the pipeline before and after the structure is connected to the pipeline can reach 35.14%. Compared with other structures, the same time pressure cycle number can be reduced after the structure is connected to the pipeline, which indicates that the number of shock wave cycles is reduced in the same time, and the pipeline system is not easy to be damaged. Therefore, both the reduction of the cycle number and the percentage of the pipeline pressure drop reflect the mitigation effect of the device on the water hammer effect, which proves that the structure has good water hammer pressure reduction effect.

[0038] Example Two:

[0039] The two parameter characteristics of the structure described in Example One are that the maximum inner diameter D of the kettle-shaped body and the main flow pipeline diameter d need to satisfy ; the internal pipeline length needs to satisfy L=10(a+b+R). Both of these two parameter characteristics are obtained by comparing a large number of experimental simulation numerical simulation data. In numerical simulation, computational fluid dynamics method is used, and multiple control parameters are set. Based on the flow simulation software, the occurrence of water hammer effect after the pipeline structure of dozens of different parameter structures is connected to the pipeline is simulated in two dimensions. In the simulation process, the compressibility of the fluid is fully considered, and the dynamic mesh technology is used to change the boundary type to simulate the generation of water hammer effect when the valve of the pipeline is suddenly closed. Finally, the pressure data of all pipelines are extracted, and the influence of different structure parameters on the water hammer mitigation effect is compared and analyzed to find the optimal structure parameters of the water hammer prevention pipeline device. Please refer to Figure 9, the length parameter L of the structure is x (a+b+R), and the pipe diameter ratio parameter D of the structure is yd, in the comparison of several structures with different parameter settings, when the parameters L=10 (a+b+R) and 5d<D<7d are met, the maximum pressure drop percentage of the structure can reach more than 50%. When the parameters L=10 (a+b+R) and D=7d are met, the structure has the best pressure drop reduction effect, and the maximum pressure drop percentage can reach 63.31%.

[0040] Embodiment three:

[0041] Please refer to Figure 7 The device can be used in series. Please refer to Figure 8 The series use of the structure can produce better reduction effect, and with the increase of the number of series, the maximum pressure drop will also increase. Please refer to Figure 6 The figure is a pressure comparison diagram of the series structure connected into the pipeline and the original pipeline, and it can be seen from the figure that when the structure is used in series, not only a good pressure drop effect is produced, but also the structure has fewer cycle numbers in the same time compared with the non-series structure, which indicates that the cycle number of the shock wave is reduced by half in the same time, and the pipeline system is more difficult to be damaged. Therefore, it is proved that the series structure has more excellent water hammer protection effect. In addition, the device can also be used in series with the existing water hammer protection device in the original pipeline, which can effectively reduce the damage caused by the huge pressure wave of water hammer effect to the water hammer protection device, pipeline and valve, prolong the service life of the water hammer protection device, and protect these devices.

[0042] The remaining matters of the present application are known technologies.

[0043] The above embodiments are only for illustrating the technical concept and characteristics of the present application, and the purpose is to enable those skilled in the art to understand the content of the present application and implement it, and cannot limit the protection scope of the present application. Any equivalent changes or modifications made according to the spirit and essence of the present application shall be covered within the protection scope of the present application.

Claims

1. A device for mitigating pressure peaks caused by water hammer in pipelines, characterized in that, include: The inlet connecting pipe (1) has a positive flow inlet (101) on the left side, which is used to connect to the external main pipe; The outlet connecting pipe (3) has a reverse flow inlet (102) on the right side, which is used to connect to the external main pipe; The pot-shaped body (2) is recessed inward on the left side, and the inner diameter of the recess is the same as that of the main pipe. The inner diameter of the pot-shaped body (2) decreases from left to right to the same as that of the pipe. The left and right ends are connected to the inlet connecting pipe (1) and the outlet connecting pipe (3) respectively. The pot-shaped body (2) is an axisymmetric pipe, which is a hollow pipe formed by the axis of rotation around the axis of the pipe; The rotation curves on the inner side of the jar-shaped body (2) include: The straight section (201) is set at an angle to the pipe axis. The "flat cone" structure formed by the straight section (201) rotating around the axis is the diffusion section after the fluid enters from the reverse flow inlet (102). The fluid velocity decreases and a uniform flow is formed on a wider cross section. The arc segment has one end tangent to the end of the straight segment (201) and the other end tangent to the axis of the main pipeline. The arc segment is a curved arc segment in the Fibonacci spiral. The curved arc segment includes a 90-degree sector arc defined by two squares with side lengths a and b, which are the key parameters of the Fibonacci spiral. The two sector arc segments are connected to form the curved arc segment, and a / b = 1.61803. The internal pipe length of the pot-shaped body is L=10(a+b+R), where L is the length of the internal pipe, the starting point of the length is the tangent point between arc segment I (202) and the main pipe, and the ending point is the connection point between the straight segment and the main pipe; where a is the side length of the square circumscribed by arc segment II (205) of the Fibonacci spiral, b is the side length of the square circumscribed by arc segment I (202) of the Fibonacci spiral, and R is the radius of the main circular pipe.

2. The device for mitigating the peak pressure of water hammer in pipelines according to claim 1, characterized in that, The inlet and outlet diameters of the pot-shaped body (2) are the same, and are consistent with the diameters of the inlet connecting pipe (1), the outlet connecting pipe (3), and the external main pipe.

3. The device for mitigating the peak pressure of water hammer in pipelines according to claim 1, characterized in that, The straight segment (201) is at an angle of 15~30° to the pipeline axis.

4. The device for mitigating water hammer pressure peaks in pipelines according to claim 1, characterized in that, The maximum inner diameter D of the pot-shaped body and the diameter d of the main pipe satisfy the following condition: .

5. The device for mitigating the peak pressure of water hammer in pipelines according to claim 1, characterized in that, The device for mitigating the peak pressure of water hammer in the pipeline is connected in series in the pipeline.

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