CN113311880B - Automatic flow field uniformity adjusting device for large-scale flow-making water tank based on Pascal principle - Google Patents

Abstract

The invention provides an automatic adjustment device for the flow field uniformity of a large-scale flow-making pool based on Pascal's principle, including: a flow-making corridor system, a water distribution pipe group system, a hydraulic valve system, and a hydraulic control system. This invention adopts all mechanical systems and cleverly relies on the Pascal principle of the hydraulic system without any electronic circuit or automatic measurement control. It has high structural reliability and is easy to implement, and can ensure inflow under any inflow situation, working water depth and other working conditions. The uniformity of flow avoids the limitation that measures such as diversion line optimization can only achieve optimality under a single working condition.

Description

Automatic adjustment device for flow field uniformity in large flow pools based on Pascal's principle

Technical field

The invention relates to the technical field of water conservancy ports and ocean model testing, and more specifically, to an automatic adjustment device for flow field uniformity in a large-scale flow-making pool based on Pascal's principle.

Background technique

The current-making pool test system is an important means of simulating natural river water and tidal flow, and studying the current flow field and its interaction with structures. It is widely used in the fields of hydraulic engineering, port and coastal engineering, and ocean engineering; in addition, current and wave making Coupled simulation of , wind, earthquake and other effects can study more complex extreme natural environments and provide strong support for engineering design and disaster prevention and reduction.

In the design of flow pools, the uniformity of the flow field is a crucial indicator. In most studies, the laboratory needs to simulate the flow environment at a specific flow rate in nature (rivers or oceans), so the flow field structure needs to be as uniform as possible in the flow pool. However, due to the limitations of the experimental site space, it is often necessary to construct the flow system in a relatively narrow space. The water pipelines or corridors, entrance diversion, outlet diversion and other parts should be compressed as much as possible to reduce the limited space. Leave it to the flow test area. Sharp turns in water pipelines or corridors are often unavoidable, posing great challenges to the uniformity of the test flow field. Taking the current flow field in Figure 1 as an example, the water flow is input from the right corridor, and after a 90-degree turn, flows upward into the water flow test area. As shown in Figures 1 and 2, due to the obvious local vortex structure in the flow field at the entrance, the uniformity of the water flow at the pool entrance section MM is difficult to meet the test requirements; installing a series of shunt pipes in the pool entrance section for rectification can ensure The flow rate of the water entering the pool in the pipe is upward along the pool, but due to the complex structure of the local flow field, it is difficult to ensure that the flow rate in the shunt pipe is the same. How to ensure that the flow rate from each branch pipe is the same, that is, the flow rate of pipes A, B, and C in Figure 2 is equal, is a key technical problem that needs to be solved in the design of the flow-making system. The inlet area of a large pool is large, and the water flow is easy to disperse, making the problem of flow field uniformity more prominent.

At present, the control of the inflow speed of the flow pool is mainly achieved by optimizing the diversion and rectification design or by controlling the opening of a series of distributed valves. For example, the patent "Parallel-flow Deepwater Flow Making System and Method" (Application No. 200610025220.5) designs a six-layer flow making device. Each layer of flow making device is composed of a driving water pump, a water inlet pipe, and a water outlet pipe, and is installed on the pipe through adjustment. The valve controls the on and off, so that the energy of the water pump driven by the flow-making device is distributed among the vertical flow-making devices at each layer, thereby creating various cross-sectional flows. The patent "Compound Rectification Device of Deep Water Test Pool Flow Making System" (Application No. 200610148237. After the jet from the flow nozzle hits the rectifier block, it reaches a uniform and stable state. The patent "A Deep Water Flow Making System with Pressure Perforated Wall Structure" (Application No. 201320808079.1) uses pressure perforated wall blocks to connect horizontal plates and columns with reinforced concrete laterally, and longitudinally with steel plates and "U"-shaped steel plates at both ends welded into a whole. The structure's rectifying wall achieves uniformity of the flow field. The patent "A Deep Water Test Pool Integrated Flow Making Structure" (Application No. 201520011068. The channel layers are equipped with independent flow-making water pumps and a layered flow-making system composed of connected inlet and outlet corridors. Each layer of flow-making system is independent of each other and can simulate different flow rates at different depths to ensure that the water flow is in the width direction of the pool. The overall uniformity and stability achieve the rectification effect of uniform flow rate. The patent "A flow-making system for deep-water test pools" (Application No. 201620578366.1) uses round-to-square connecting sections, rectifying walls and lifting platforms to achieve uniformity adjustment of the flow field. The patent "An Underwater Vibrating Table Omnidirectional Flow-Making Pipeline System" (Application No. 201820945458.8) designs the confluence area as an "L"-shaped structure and is arranged axially symmetrically outside the flow-making pool to optimize the inflow velocity. The above-mentioned optimized design, valve or outlet adjustment can often improve the uniformity of the flow field, but it does not guarantee the optimal hydrodynamic performance of the flow field diversion and the strict uniformity of the flow field under various water depth and flow conditions.

By adding automatic control and real-time monitoring and feedback of the flow field, the uniformity of the flow-making system under different working conditions can be better met. For example, the patent "Intelligent Adaptive Flow Diversion Device for Wave Flow Test Pool" (Application No. 201821382323.1) is based on the flow rate monitoring system's real-time monitoring of speed distribution and flow conditions, and with the guide plate that intelligently adjusts the inflow direction in real time, it can control a variety of water depths. Accurately simulate the working conditions under the combined conditions of flow rate and flow rate, and achieve optimal uniformity. The patent "An omnidirectional flow-making device and method in a wave pool" (Application No. 202010234692.1) opens in real time the N outflow valves and the corresponding N return valves in the flow field required for the experiment in the wave pool, and closes the M outflow valves and corresponding M return valves outside the flow field required for the experiment realize the selection of a certain flow field direction. Through automatic control and real-time monitoring, this type of design can adjust and optimize the flow field uniformity in the flow pool through computer software control. Its disadvantage is that it involves relatively complex automation control and electronic circuit systems, which are costly to implement and prone to failure. In addition, the computer software algorithms used for automated adjustment also present significant challenges.

Therefore, there is an urgent need in the existing technology for a technical solution that can automatically adapt to changes in the incoming flow and ensure the uniformity of the flow field.

Contents of the invention

The invention provides an automatic adjustment device for flow field uniformity of a large flow-making pool based on Pascal's principle.

In order to solve the above technical problems, the present invention provides the following technical solutions.

An automatic adjustment device for flow field uniformity in large flow pools based on Pascal's principle, including:

The flow-making corridor system includes an inflow water-conveying corridor enclosed by fixed side walls. The front end of the incoming water-conveying corridor is connected to the external water source, and the rear end of the incoming water-conveying corridor is a flow-making corridor. The inlet of the flowing pool;

A water distribution pipe group system includes a water distribution pipe and a local obstacle, and the local obstacle is fixedly provided on the inner wall of the water distribution pipe;

A hydraulic valve system includes a flow regulating sphere, a piston rod, a hydraulic cylinder and a fixed connector. The flow regulating sphere, the piston rod and the hydraulic cylinder are connected in sequence and are located inside the water distribution pipe; the hydraulic cylinder Fixed connection with the water distribution pipe through the fixed connector;

And a hydraulic control system, including a hydraulic pipeline, a hydraulic buffer and a screw propelling piston connected in sequence. The front end of the hydraulic pipeline is connected to the end of the water distribution pipe, and a pressure gauge is also provided on the hydraulic buffer.

There are multiple water distribution pipes.

Each water distribution pipe is internally fixed with a plurality of local obstacles, and the local obstacles are evenly arranged in the middle of the inner wall of the water distribution pipe.

The diameter of the flow regulating sphere is 10cm-100cm.

The diameter of the flow regulating sphere is equal to or close to half of the inner diameter of the water distribution pipe.

The flow regulating sphere is made of hollow metal or plastic material.

The overall density of the flow regulating sphere is the same as or similar to that of the water body.

The water distribution pipe is made of metal pipe or PVC plastic pipe material.

The diameter of the hydraulic cylinder is less than 1/10 of the inner diameter of the water distribution pipe.

The water distribution pipes are arranged in a three-dimensional array.

Compared with the prior art, the beneficial effects of the present invention are:

1. All adopt mechanical systems, and cleverly use the Pascal principle of the hydraulic system, without any electronic circuits or automated measurement control, with high structural reliability and easy implementation;

2. It can ensure the uniformity of inflow flow under any inflow conditions, working water depth and other working conditions, avoiding the limitation that measures such as diversion line optimization can only achieve optimality under a single working condition.

Description of drawings

Figure 1 shows the uneven local flow field structure at the inlet of the flow pool without rectification facilities.

Figure 2 shows the local flow field structure at the inlet of the flow pool under the condition of rectification of the shunt tube group.

Figure 3 is a schematic structural diagram of the present invention.

Figure 4 is a schematic diagram of the expansion of the inflow and distribution pipe group into a three-dimensional array.

Symbols in the figure: 1 inflow water conveyance corridor, 2 inlet of the flow pool, 3 water distribution pipe, 4 flow adjustment sphere, 5 local obstacles, 6 piston rod, 7 hydraulic cylinder, 8 fixed connection, 9 hydraulic pipeline, 10 hydraulic pressure Buffer, 11 screw push piston, 12 pressure gauge.

Detailed ways

In order to enable those skilled in the art to better understand the technical features, purposes and beneficial effects of the present invention, the technical solutions of the present invention are described in detail below in conjunction with the examples, but this should not be understood as limiting the implementable scope of the present invention.

As shown in Figure 1-4, the automatic adjustment device for flow field uniformity in large-scale flow-making pools based on Pascal's principle includes:

The flow-making corridor system includes an inflow water-conveying corridor 1 enclosed by fixed side walls. The front end of the incoming water-conveying corridor 1 is connected to the external water source, and the rear end of the incoming water-conveying corridor 1 is used to create flow-making water. Pool inlet 2;

The water distribution pipe group system includes a water distribution pipe 3 and a local obstacle 5. The local obstacle 5 is fixedly installed on the inner wall of the water distribution pipe 3;

The hydraulic valve system includes a flow adjustment ball 4, a piston rod 6, a hydraulic cylinder 7 and a fixed connector 8. The flow adjustment ball 4, the piston rod 6 and the hydraulic cylinder 7 are connected in sequence and are located inside the water distribution pipe 3; the hydraulic cylinder 7 passes through The fixed connector 8 is fixedly connected to the water distribution pipe 3;

And a hydraulic control system, including a hydraulic pipeline 9, a hydraulic buffer 10 and a screw push piston 11 connected in sequence. The front end of the hydraulic pipeline 9 is connected to the end of the water distribution pipe 3. The hydraulic buffer 10 is also provided with a pressure gauge 12.

The function of the water distribution pipe group system is to provide n independent channels for water flow and adjust the flow rate of each channel in conjunction with the movement of the sphere.

Among them, the number of water distribution pipes 3 is multiple. In this embodiment, the water distribution pipes 3 are arranged in a three-dimensional array, which is an 8×5 matrix in this embodiment. The water distribution pipe 3 is made of metal pipe or PVC plastic pipe material. The gaps between different water distribution pipes 3 are filled with waterproof fillers to avoid flow loss in the gaps. Among them, each water distribution pipe 3 is provided with a plurality of local obstacles 5 internally fixed. According to the different cross-sectional shapes of the inflow corridor and the flow pool, the water distribution pipe 3 can adopt a square cross-section or even a special-shaped cross-section. The local obstacle protrusions 5 and the flow rate The adjusting sphere 4 accordingly adopts a pyramid shape, and the local obstacles 5 are evenly arranged in the middle of the inner wall of the water distribution pipe 3 .

The flow adjustment sphere 4 is used to sense the flow rate or flow rate in the pipeline, and forms a hydraulic connection through the piston rod 6 and the hydraulic cylinder 7 to ensure that the flow resistance of each flow adjustment sphere 4 is equal. The diameter of the flow regulating sphere 4 is selected between 10cm and 100cm according to the size of the flow pool, and needs to be equal to or close to half of the inner diameter of the water distribution pipe 3 . The adjusting sphere 4 is made of hollow metal or plastic material, and its overall density is the same as or similar to that of the water body, thereby avoiding the generation of buoyancy or effective gravity.

The diameter of the hydraulic cylinder 7 is smaller than 1/10 of the inner diameter of the water distribution pipe 3 in order to reduce the resistance to the water flow. The length of the hydraulic cylinder should ensure that the flow adjustment ball 4 has sufficient stroke to realize the adjustment of the flow rate from zero to the maximum value.

The hydraulic control system provides a stable liquid pressure to control and monitor the overall flow. The overall hydraulic volume can be manually adjusted by pushing the screw piston 11 so that the entire flow making system is locked at a certain flow level. The pressure gauge 12 can assist in determining the overall flow. Monitoring, when the flow rate increases, the pressure gauge 12 shows a corresponding increase in pressure.

The working principle of the present invention is as follows:

According to Pascal's principle, when any point in an incompressible stationary fluid is subjected to an external force and generates a pressure increase, this pressure increase is transmitted to all points of the stationary fluid instantaneously. Therefore, the force of the water flow on the hydraulically connected spheres must be the same. Since the water bodies between the branch pipes are connected, the static pressure of the water is not considered here. The force of the water flow on the sphere is the flow resistance F _D of the sphere. According to Pascal's principle, the flow resistance F of the sphere in different branches is _D is strictly equal and can be calculated according to the flow resistance formula:

F _D ＝C _D *A*ρ*U ² /2

In the formula, C _D is the resistance coefficient of the flow around the sphere, A is the projected area of the flow object perpendicular to the direction of the flow, ρ is the fluid density, and U is the average flow velocity of the incoming flow.

Considering the influence of the pipeline wall and local obstacles on the flow field, the local flow field influence correction coefficient ε is introduced, that is

F _D ＝ε*C _D *A*ρ*U ² /2

After the sphere, pipe, and local obstacles are set, each coefficient is also determined. Introducing Ψ = ε*C _D *A*ρ/2, then

F _D =Ψ*U ²

According to the above formula, when the resistance F _D of the water flow around each sphere is the same, the average flow velocity U of the corresponding pipes is also the same, that is, the outflow flow rate of each branch pipe is equal, thus ensuring the uniformity of the flow distribution at the inlet of the flow pool.

Taking the i-th branch pipe as an example, when the flow rate or flow rate of the i-th branch pipe is small, the flow resistance F _D of the corresponding sphere i will inevitably decrease, the pressure of the hydraulic cylinder corresponding to the pipe will decrease, and other parts of the liquid in the connector will inevitably flow. Branch pipe i causes the piston of hydraulic cylinder i to stretch and the pistons of other hydraulic cylinders to compress. This results in an increase in the flow rate of branch pipe i, and ultimately results in the same flow rate of all branch pipes.

In addition, the average flow velocity U in each branch pipe is closely related to the position of the sphere. Suppose the coordinate of the sphere along the pipeline streamline direction when the valve is completely closed is x ₀ , and the current coordinate of sphere i is x _i , then the average flow velocity U in the pipe _i , flow Q _i can be expressed in the following functional form:

U _i =f(x _{0 –xi} ) or Q _i =g(x _{0 –xi} )

The total flow Q can be calculated using the following formula:

Q=∑Q _i =∑g(x ₀ –x _i )

Assuming that the flow rate and valve opening are linearly related, the above can be rewritten as

Q＝g(∑(x ₀ –x _i ))

where ∑(x ₀ –x _i ) is the algebraic sum of piston strokes of all hydraulic cylinders, which is related to the total volume of liquid in the hydraulic system. Therefore, the total flow rate of flow creation can be adjusted by adjusting the total volume of liquid in the hydraulic system.

In addition, according to F _D =ε*C _D *A*ρ*U ² /2, based on the pressure of the hydraulic system without flow, the current pressure P of the hydraulic system is

P＝F _D /A＝ε*C _D *ρ*U ² /2

The above formula can also be abbreviated as the relationship between flow rate and pressure, that is

P＝ζQ ²

In the formula, ζ is the flow coefficient. Therefore, the total flow rate in the pipeline can be estimated by observing the pressure P of the hydraulic system.

The inflow flow Q of the incoming water conveyance corridor 1 passes through the n pipe outlets at the inlet 2 of the flow-making pool, and the overall flow Q is divided into n small flows of Q/n, and is input into the flow-making pool.

The overall inflow flow of the flow is achieved by rotating the screw to push the piston 11 and adjusting the liquid volume in the hydraulic buffer 10 . When the liquid volume in the hydraulic buffer 10 increases, the liquid in each hydraulic cylinder 7 decreases, the flow adjustment sphere 4 shrinks toward the local obstacle 5, and the flow flow decreases until it is completely closed; when the liquid in the hydraulic buffer 10 When the liquid volume decreases, the liquid in each hydraulic cylinder 7 increases, the flow adjustment sphere 4 extends in a direction away from the local obstacle 5, and the flow rate increases until the maximum flow rate is reached. When the liquid volume in the hydraulic buffer 10 is fixed, the overall opening of the valves in each water distribution pipe 3 remains unchanged. At this time, if the incoming flow rate increases, the force on the flow adjustment ball 4 will increase, further affecting the When the hydrostatic pressure of the hydraulic system is reached, the reading of the pressure gauge 12 will increase, otherwise the reading will decrease. According to the reading of the pressure gauge 12, the increase or decrease trend of the flow rate can be judged.

The above are only preferred embodiments of the present invention, but the present invention is not limited to the above-mentioned specific embodiments. For those of ordinary skill in the art, without departing from the creative concept of the present invention, other modifications can be made. There are several modifications and improvements, which all belong to the protection scope of the present invention.

Claims (7)

1. An automatic adjustment device for flow field uniformity in large-scale flow-making pools based on Pascal's principle. Its characteristics include: The flow-making corridor system includes an inflow water-conveying corridor (1) enclosed by fixed side walls. The front end of the incoming water-conveying corridor (1) is connected to an external water source. The incoming water-conveying corridor (1) The rear end of the channel (1) is the inlet (2) of the flow pool; The water distribution pipe group system includes a water distribution pipe (3) and a local obstacle (5). The local obstacle (5) is fixedly installed on the inner wall of the water distribution pipe (3); Hydraulic valve system includes a flow adjustment ball (4), a piston rod (6), a hydraulic cylinder (7) and a fixed connection (8). The flow adjustment ball (4), the piston rod (6) and the The hydraulic cylinders (7) are connected in sequence and are located inside the water distribution pipe (3); the hydraulic cylinder (7) is fixedly connected to the water distribution pipe (3) through the fixed connector (8); and The hydraulic control system includes a hydraulic pipeline (9), a hydraulic buffer (10) and a screw push piston (11) connected in sequence. The front end of the hydraulic pipeline (9) is connected to the end of the water distribution pipe (3) , the hydraulic buffer (10) is also provided with a pressure gauge (12); Wherein, the number of the water distribution pipes (3) is multiple; and the water distribution pipes (3) are arranged in a three-dimensional array; each water distribution pipe (3) is provided with a plurality of local obstacles (5) internally fixed. The obstacles (5) are evenly arranged in the middle of the inner wall of the water distribution pipe (3). 2. The automatic adjustment device for flow field uniformity in a large flow pool based on Pascal's principle according to claim 1, characterized in that the diameter of the flow adjustment sphere (4) is 10cm-100cm. 3. The automatic adjustment device for flow field uniformity in a large flow pool based on Pascal's principle according to claim 1, characterized in that the diameter of the flow adjustment sphere (4) is equal to or close to the inner diameter of the water distribution pipe (3) half of. 4. The automatic adjustment device for flow field uniformity in a large flow pool based on Pascal's principle according to claim 1, characterized in that the flow adjustment sphere (4) is made of hollow metal or plastic material. 5. The automatic adjustment device for flow field uniformity in a large flow pool based on Pascal's principle according to claim 1, characterized in that the overall density of the flow adjustment sphere (4) is the same as or similar to that of the water body. 6. The automatic adjustment device for flow field uniformity of a large-scale flow-making pool based on Pascal's principle according to claim 1, characterized in that the water distribution pipe (3) is made of metal pipe or PVC plastic pipe material. 7. The automatic adjustment device for flow field uniformity of a large-scale flow-making pool based on Pascal's principle according to claim 1, characterized in that the diameter of the hydraulic cylinder (7) is less than 1/1 of the inner diameter of the water distribution pipe (3). 10.