Water turbine pressure equalizing pipe, water turbine system and water turbine pressure equalizing pipe design method

Abstract

The invention relates to the technical field of water turbines, in particular to a water turbine pressure equalizing pipe, a water turbine system and a water turbine pressure equalizing pipe design method.The water turbine pressure equalizing pipe comprises a pressure equalizing pipe body, a pressure equalizing pipe body installation hole plate, and an overflowing through hole is formed in the hole plate and coaxially arranged with the pressure equalizing pipe body; the inner diameter of the overflowing through hole is smaller than the pipe diameter of the pressure equalizing pipe body, local resistance is generated through the overflowing through hole, the speed and pressure distribution of fluid are influenced, the flow and pressure of the fluid can be effectively controlled by reasonably selecting the size of the overflowing through hole, and multiple factors influencing the stability of a unit, such as leakage flow, pressure loss and axial force, can be balanced; the requirements for reducing the leakage flow between the rotating wheel and the top cover, maintaining proper gap cavity pressure and reducing the air supply amount of the top cover are met, the stability and reliability of a unit are improved by reducing the air supply amount and generating an inhibiting effect on the vibration and noise level, and in addition, the control effect of fluid leakage can be optimized due to the fact that gaps of the pore plate and the leakage stopping ring are matched with each other.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic turbines, and particularly to a pressure equalizing pipe for a hydraulic turbine, a hydraulic turbine system, and a design method for a pressure equalizing pipe of a hydraulic turbine. Background Art

[0002] As an important hydraulic power generation equipment, the operation stability of a hydraulic turbine is directly related to the reliability and efficiency of the entire power supply system. A Francis turbine, also known as a mixed-flow turbine, belongs to a type of reaction turbine. The main components of a Francis turbine include a spiral case, a stay ring, a guide vane mechanism, a top cover, a runner, a main shaft, a guide bearing, a bottom ring, a draft tube, etc. Among them, the runner is composed of a crown, a sealing ring, and a number of fixed blades, and the draft tube is a water discharge component of the hydraulic turbine that guides the water flow at the runner outlet downstream.

[0003] In a Francis turbine system, due to the imbalance between the fluid pressure in the clearance cavity between the runner and the top cover and the fluid pressure in the runner, a large axial force will be generated on the runner during the operation of the hydraulic turbine. Sometimes, due to unreasonable design of the clearance cavity or the sealing ring, the vibration of the top cover may exceed the standard, and it is necessary to connect the clearance cavity and the draft tube through a pressure equalizing pipe and use air injection to reduce vibration.

[0004] Existing pressure equalizing pipes are generally of a conventional pipe structure. Due to the complexity and variability of the fluid flow in the clearance cavity between the crown and the top cover and in the pressure equalizing pipe, as well as the installation error of the sealing ring, etc., situations such as flow leakage and pressure loss will occur in the clearance cavity. It has been found through research that after pressure balance is achieved through the pressure equalizing pipe, the smaller the axial force generated in the crown cavity, the more serious the situations such as flow leakage and pressure loss in the clearance cavity. And if the situations such as flow leakage and pressure loss in the clearance cavity are to be reduced, a large axial force will be generated on the runner. In some cases, flow leakage and pressure loss in the clearance cavity will cause problems such as self-excited oscillation of the clearance cavity, vibration of the top cover, and increased noise, which may have an adverse impact on the safety and service life of the equipment. It is necessary to supplement vibration reduction to the clearance cavity, but often a large amount of air injection is required, and sometimes it is difficult to achieve an ideal vibration reduction effect even when the air compressor is turned to its maximum power. At the same time, the air compressor also brings additional noise.

[0005] Therefore, it is urgent to balance the relationship between flow leakage, pressure loss, and axial force in the clearance cavity to reduce pressure pulsation, noise, reduce the energy consumption and water consumption of the unit during operation, and improve the efficiency of the unit. Summary of the Invention

[0006] The present invention provides a pressure equalizing pipe for a water turbine, a water turbine system and a design method for the pressure equalizing pipe of a water turbine, so as to solve the above-mentioned defects caused by balancing pressure through the pressure equalizing pipe in the existing Francis turbine system, realize effective control of the pressure in the clearance cavity and the leakage amount, and without affecting the overall axial force of the unit, thereby reducing the demand for air supplement of the unit, reducing the operating energy consumption and water consumption of the unit, and improving the efficiency of the unit.

[0007] The present invention provides a pressure equalizing pipe for a water turbine, including a pressure equalizing pipe body, an orifice plate is installed on the pressure equalizing pipe body, the orifice plate is provided with a flow through hole, the flow through hole is coaxially arranged with the pressure equalizing pipe body, and the inner diameter of the flow through hole is smaller than the pipe diameter of the pressure equalizing pipe body, so that when the fluid passes through the pressure equalizing pipe body, the flow rate changes at the flow through hole.

[0008] According to the pressure equalizing pipe for a water turbine provided by the present invention, the pressure equalizing pipe body includes a first pipe body and a second pipe body with equal diameters, the orifice plate is a circular orifice plate, and the first pipe body, the orifice plate and the second pipe body are detachably connected in sequence.

[0009] According to the pressure equalizing pipe for a water turbine provided by the present invention, a first flange is arranged at the end of the first pipe body, and a second flange is arranged at the end of the second pipe body; a plurality of bolt holes are distributed along the circumference of the orifice plate, and the first flange, the orifice plate and the second flange are tightly connected by bolts.

[0010] According to the pressure equalizing pipe for a water turbine provided by the present invention, sealing elements are arranged between the end faces of the first flange opposite to the orifice plate and between the end faces of the second flange opposite to the orifice plate.

[0011] According to the pressure equalizing pipe for a water turbine provided by the present invention, the first flange and the second flange are made of high carbon steel.

[0012] The bolts used for tightly connecting the first flange, the orifice plate and the second flange are hexagon bolts made of high-strength stainless steel.

[0013] The sealing element is a polytetrafluoroethylene sealing ring, and a plurality of the sealing elements are distributed from the center to the periphery between the end faces of the first flange opposite to the orifice plate and between the end faces of the second flange opposite to the orifice plate respectively.

[0014] According to the pressure equalizing pipe for a water turbine provided by the present invention, the inner diameter of the flow through hole is 35% - 40% of the pipe diameter of the pressure equalizing pipe body.

[0015] The present invention also provides a water turbine system, including the pressure equalizing pipe for a water turbine according to any one of the above.

[0016] The present invention also provides a design method for the equalizing pipe of a water turbine, which is applicable to the design of the equalizing pipe of the water turbine described in any one of the above. By designing the through-flow hole diameter of the orifice plate of the equalizing pipe of the water turbine, the impedance of the equalizing pipe of the water turbine is adjusted.

[0017] According to a design method for the equalizing pipe of a water turbine provided by the present invention, the design of the through-flow hole diameter of the orifice plate of the equalizing pipe of the water turbine includes: Respectively install the orifice plates with different through-flow hole diameters on the equalizing pipe body, and take the ratio of the diameter of the through-flow hole of the orifice plate to the inner diameter of the equalizing pipe body as the relative diameter.

[0018] Perform a water turbine fluid flow simulation on the equalizing pipe body installed with orifice plates of different diameters, and record the axial force generated on the water turbine runner after the fluid passes through the equalizing pipe body installed with orifice plates of different diameters.

[0019] Based on the minimum axial force among the axial forces generated on the water turbine runner by the equalizing pipe bodies with orifice plates of different diameters, calculate the difference between the remaining axial forces and the minimum axial force, and take the ratio of the difference to the minimum axial force as the relative axial force.

[0020] Draw a relative axial force - relative diameter relationship curve based on the relative diameter and the corresponding relative axial force.

[0021] Take the through-flow hole diameter value corresponding to the inflection point region in the relative axial force - relative diameter relationship curve as the design diameter, and take the equalizing pipe of the water turbine corresponding to the through-flow hole with the design diameter as the designed equalizing pipe of the water turbine.

[0022] According to a design method for the equalizing pipe of a water turbine provided by the present invention, the design of the through-flow hole diameter of the orifice plate of the equalizing pipe of the water turbine includes: Respectively install the orifice plates with different through-flow hole diameters on the equalizing pipe body, and take the ratio of the diameter of the through-flow hole of the orifice plate to the inner diameter of the equalizing pipe body as the relative diameter.

[0023] Perform a water turbine fluid flow simulation on the equalizing pipe body installed with orifice plates of different diameters. Record the flow rate before the fluid passes through the equalizing pipe body as the main flow rate, and take the difference between the flow rate after the fluid enters the gap cavity between the runner and the top cover and the main flow rate as the leakage flow rate.

[0024] Based on the main flow rate, calculate the ratio of the leakage flow rate corresponding to the equalizing pipe body with orifice plates of different diameters to the main flow rate as the relative flow rate.

[0025] Draw a relative flow rate - relative diameter relationship curve based on the relative diameter and the corresponding relative flow rate.

[0026] Take the orifice diameter value corresponding to the inflection point region in the relative flow rate - relative diameter relationship curve as the design orifice diameter, and take the equalizing pipe of the water turbine corresponding to the orifice with the design orifice diameter as the design water turbine equalizing pipe.

[0027] The water turbine equalizing pipe, water turbine system and water turbine equalizing pipe design method provided by the present invention install an orifice plate inside the pipe body of the equalizing pipe. The center of the orifice plate is provided with a flow - through orifice coaxial with the pipe body of the equalizing pipe. The inner diameter of the flow - through orifice is smaller than the pipe diameter of the equalizing pipe body. When the fluid passes through the equalizing pipe, the flow rate changes at the flow - through orifice, generating local resistance, thereby affecting the velocity and pressure distribution of the fluid. Since the diameter of the flow - through orifice is small, a throttling point will be formed, resulting in an increase in fluid velocity and a decrease in pressure. By reasonably selecting the size of the flow - through orifice, the flow rate and pressure of the fluid can be effectively controlled, balancing multiple factors affecting the stability of the unit such as leakage flow rate, pressure loss, and axial force, reducing the leakage flow rate between the runner and the top cover, maintaining an appropriate clearance cavity pressure, reducing the demand for top - cover air injection, improving the vibration and noise levels by reducing the air injection volume, and having a small impact on the axial force of the water turbine, thereby improving the stability and reliability of the entire system. In addition, the gap between the orifice plate and the anti - leakage ring cooperates with each other, and can also optimize the control effect of fluid leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0029] Figure 1 is a schematic cross - sectional view of the water turbine equalizing pipe provided by the present invention.

[0030] Figure 2 is Figure 1 the schematic view in the direction A of

[0031] Figure 3 is a schematic flow chart of a water turbine equalizing pipe design method provided by the present invention.

[0032] Figure 4 is the relative axial force - relative diameter relationship curve graph in the embodiment of the present invention.

[0033] Figure 5 is a schematic flow chart of another water turbine equalizing pipe design method provided by the present invention.

[0034] Figure 6 is the relative flow rate - relative diameter relationship curve graph in the embodiment of the present invention.

[0035] Reference numerals: 1, equalizing pipe body; 11, first pipe body; 12, second pipe body; 13, first flange; 14, second flange; 2, orifice plate; 3, flow-through hole; 4, seal. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0037] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the embodiments of the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0038] In the description of the embodiments of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present invention can be understood according to specific situations.

[0039] In the embodiments of the present invention, unless otherwise clearly specified and limited, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on" the second feature may be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "under" the second feature may be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

[0040] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0041] The following combines Figures 1 to 6 to describe the equalizing pipe of a water turbine, the water turbine system, and the design method of the equalizing pipe of a water turbine of the present invention.

[0042] One embodiment of the present invention provides an equalizing pipe of a water turbine. Combining Figure 1 and Figure 2 as shown, the equalizing pipe of the water turbine includes an equalizing pipe body 1. An orifice plate 2 is installed on the equalizing pipe body 1. The orifice plate 2 is provided with a flow-through hole 3. The flow-through hole 3 is coaxially arranged with the equalizing pipe body 1, and the inner diameter of the flow-through hole 3 is smaller than the diameter of the equalizing pipe body 1, so that when the fluid passes through the equalizing pipe body 1, a flow change occurs at the flow-through hole 3.

[0043] It can be understood that for the equalizing pipe of the water turbine in this embodiment, the equalizing pipe body 1 and the orifice plate 2 with the flow-through hole 3 constitute the basic structure of the equalizing pipe. The gap cavity between the runner and the top cover inside the water turbine is connected to the draft tube through the equalizing pipe of this embodiment to achieve pressure balance.

[0044] It should be understood that the orifice plate 2 is installed inside the equalizing pipe body 1, and its specific position can be adjusted according to actual requirements. A flow-through hole 3 coaxial with the equalizing pipe body 1 is provided at the center of the orifice plate 2. The inner diameter of the flow-through hole 3 is smaller than the diameter of the equalizing pipe body 1. When the fluid passes through the equalizing pipe, the flow rate changes at the flow-through hole 3, generating local resistance, which in turn affects the velocity and pressure distribution of the fluid. Due to the small diameter of the flow-through hole 3, a throttling point is formed, resulting in an increase in fluid velocity (according to the continuity equation) and a decrease in pressure (according to Bernoulli's equation). By reasonably selecting the size of the flow-through hole 3, the flow rate and pressure of the fluid can be effectively controlled, balancing multiple factors affecting the stability of the unit, such as leakage flow rate, pressure loss, and axial force, reducing the leakage flow rate between the runner and the top cover, maintaining an appropriate clearance cavity pressure, reducing the demand for top cover air injection, and reducing the vibration and noise levels of the unit with less impact on the axial force of the water turbine, thereby improving the stability and reliability of the system. In addition, the gap between the orifice plate and the anti-leakage ring can be coordinated to optimize the control effect of fluid leakage.

[0045] In some embodiments of the equalizing pipe of the water turbine of the present invention, continue to refer to Figure 1 As shown, the equalizing pipe body 1 includes a first pipe body 11 and a second pipe body 12 with the same diameter. The orifice plate 2 is a circular orifice plate, and the first pipe body 11, the orifice plate 2, and the second pipe body 12 are detachably connected in sequence.

[0046] It can be understood that the first pipe body 11 and the second pipe body 12 have the same inner diameter and outer diameter, ensuring that the fluid will not generate unnecessary pressure loss or flow disturbance due to the change in pipe diameter when passing through. The first pipe body 11 and the second pipe body 12 are respectively located on both sides of the orifice plate 2, jointly forming a complete equalizing pipeline. The detachable connection of the first pipe body 11, the orifice plate 2, and the second pipe body 12 makes the installation and replacement of the orifice plate 2 very convenient. The operator can quickly adjust and replace the orifice plate 2 according to actual requirements to change the size of the flow-through hole 3 to adapt to different working conditions. By precisely setting the size of the flow-through hole 3 on the orifice plate 2, the flow rate and pressure distribution of the fluid can be effectively controlled, reducing the leakage flow rate between the runner and the top cover, maintaining an appropriate clearance cavity pressure, and reducing the demand for top cover air injection.

[0047] In some specific examples, a first flange 13 is provided at the end of the first pipe body 11, and a second flange 14 is provided at the end of the second pipe body 12; a plurality of bolt holes are distributed circumferentially on the orifice plate 2, and the first flange 13, the orifice plate 2, and the second flange 14 are fixedly connected by bolts.

[0048] The orifice plate 2 is circular in design, and a flow-through hole 3 is provided at its center. The diameter of the orifice is smaller than the diameter of the pressure equalizing pipe, so as to achieve precise control of the fluid flow rate and pressure. The flow-through hole 3 is coaxially arranged with the pipe body 1 of the pressure equalizing pipe, ensuring that the fluid can pass through evenly, and the flow rate changes at the flow-through hole 3, generating local resistance, thereby affecting the velocity and pressure distribution of the fluid. A plurality of bolt holes are evenly distributed along the circumference of the orifice plate 2, and these holes are matched with the corresponding holes on the first flange member 13 and the second flange member 14. Bolts are used to firmly fasten the first flange member 13, the orifice plate 2, and the second flange member 14 together, which not only ensures the reliability of the connection but also facilitates disassembly and maintenance.

[0049] Furthermore, sealing members 4 are provided between the end faces of the first flange member 13 opposite to the orifice plate 2 and between the end faces of the second flange member 14 opposite to the orifice plate 2. The sealing between the first flange member 13, the orifice plate 2, and the second flange member 14 is achieved through the sealing members 4, ensuring that no leakage occurs during the process of the fluid passing through the pressure equalizing pipe.

[0050] In some specific examples of the pressure equalizing pipe of the water turbine of the present invention, the first flange member 13 and the second flange member 14 are made of high carbon steel and are in the shape of standard circular flanges to ensure effective connection with the pipeline. The first flange member 13 and the second flange member 14 made of high carbon steel have enhanced tensile strength and corrosion resistance, and are suitable for high-pressure and high-temperature working environments. They are fixedly connected to the pressure equalizing pipe through evenly distributed bolt connections, ensuring the stability and sealing performance of the connection, thereby effectively reducing the risk of fluid leakage.

[0051] The bolts used for fastening and connecting the first flange member 13, the orifice plate 2, and the second flange member 14 are hexagon bolts made of high-strength stainless steel, which are convenient for tightening with a wrench. The bolt design takes into account the tensile strength in a high-pressure environment to ensure that the flange connection can withstand sufficient pressure. The flange is firmly fixed through a uniform tightening torque, ensuring the stability and sealing performance of the connection, and effectively preventing equipment failures caused by excessive local stress.

[0052] The orifice plate 2 is of circular structure and is made of high-strength corrosion-resistant material. The diameter and shape of the flow-through hole 3 of the orifice plate 2 can be designed and adjusted according to actual flow requirements. The surface of the orifice plate 2 is smooth without sharp corners, avoiding vortex and turbulence phenomena caused by fluid impact.

[0053] The seal 4 is a polytetrafluoroethylene sealing ring. A plurality of seals 4 are distributed from the center to the periphery between the end faces of the first flange member 13 opposite to the orifice plate 2 and between the end faces of the second flange member 14 opposite to the orifice plate 2 respectively. The seal 4 is made of polytetrafluoroethylene (PTFE) material, is annular in shape, and is used for the flange connection. The seal 4 is selected from materials with high temperature resistance and corrosion resistance to provide excellent sealing effect under high-pressure environment and prevent fluid leakage. The seal 4 is installed between the first flange member 13, the orifice plate 2 and the second flange member 14, and is pressed through the fastening force of the flange to ensure good sealing performance during the operation of the water turbine.

[0054] Based on the structures in the above several embodiments of the equalizing pipe of the water turbine of the present invention, in some embodiments, the inner diameter of the flow-through hole 3 is 35% - 40% of the diameter of the pipe body 1 of the equalizing pipe. It can be understood that the inner diameter of the flow-through hole 3 in this embodiment is based on the principles of fluid mechanics and actual application requirements, aiming to achieve the best flow control and pressure regulation effects. By setting the inner diameter of the flow-through hole 3 to be 35% - 40% of the diameter of the pipe body 1 of the equalizing pipe, it is possible to significantly increase the local resistance on the premise of ensuring a certain flow rate, thereby effectively controlling the flow rate of the fluid. The selection of the inner diameter of the flow-through hole 3 in this embodiment can well balance multiple factors affecting the stability of the unit, such as leakage flow rate, pressure loss, and axial force, effectively control the pressure and leakage volume in the crown seal cavity, and does not affect the overall axial force of the unit. On the basis of reducing the air supply volume of the unit, it can reduce pressure pulsation and noise, optimize the operation energy consumption and water consumption of the unit, and thus improve the efficiency and operation stability of the unit.

[0055] On the other hand, the present invention also provides a water turbine system, including the equalizing pipe of the water turbine in any one of the above embodiments. It can be understood that since the water turbine system of the present invention includes the equalizing pipe of the water turbine of the present invention, the water turbine system has various advantages possessed by the above equalizing pipe of the water turbine, that is, it can effectively balance the flow leakage, pressure loss, and axial force during the operation of the water turbine system through the equalizing pipe of the water turbine. With the function of reducing the air supply volume, it can reduce pressure pulsation and noise, and at the same time optimize the operation energy consumption and water consumption of the system, thereby improving the efficiency and stability of the water turbine system.

[0056] The equalizing pipe of the water turbine of the present invention can not only be used in the designed Francis conventional units and pumped storage units, but also is very convenient for the layout and installation in the top covers of the units under construction and already built. By reasonably designing the throttling orifice plate of the equalizing pipe and the clearance with the anti-leakage ring, it is possible to effectively reduce the air supply volume of the unit, thereby indirectly improving the smoothness of equipment operation, reducing environmental noise, and helping to extend the service life of related equipment.

[0057] On the other hand, the present invention also provides a design method for the equalizing pipe of a water turbine, which is applicable to the design of the equalizing pipe of the water turbine in any of the above embodiments. By designing the aperture of the flow-through hole 3 of the orifice plate 2 of the equalizing pipe of the water turbine, the impedance of the equalizing pipe of the water turbine is adjusted.

[0058] In some embodiments of the design method for the equalizing pipe of the water turbine provided by the present invention, referring to Figure 3 as shown, the steps of designing the aperture of the flow-through hole 3 of the orifice plate 2 of the equalizing pipe of the water turbine include the following steps S1 to S5.

[0059] S1. Orifice plates 2 with different apertures of the flow-through hole 3 are respectively installed on the equalizing pipe body 1, and the ratio of the aperture of the flow-through hole 3 of the orifice plate 2 to the inner diameter of the equalizing pipe body 1 is used as the relative diameter.

[0060] S2. Perform a fluid flow simulation on the equalizing pipe body 1 with orifice plates of different apertures installed, and record the axial force generated on the water turbine runner after the fluid passes through the equalizing pipe body 1 with orifice plates of different apertures installed.

[0061] S3. Based on the minimum axial force among the axial forces generated on the water turbine runner by the equalizing pipe body 1 with orifice plates of different apertures, calculate the difference between the remaining axial forces and the minimum axial force, and use the ratio of the difference to the minimum axial force as the relative axial force.

[0062] S4. Draw a relative axial force - relative diameter relationship curve based on the relative diameter and the corresponding relative axial force.

[0063] S5. Take the aperture value of the flow-through hole 3 corresponding to the inflection point region in the relative axial force - relative diameter relationship curve as the design aperture, and take the equalizing pipe of the water turbine corresponding to the flow-through hole 3 with the design aperture as the designed equalizing pipe of the water turbine.

[0064] It can be understood that the design method for the equalizing pipe of the water turbine in this embodiment is to record the axial force generated on the water turbine runner by orifice plates 2 with different apertures through a series of fluid flow simulation experiments, and draw a relative axial force - relative diameter relationship curve based on these data to determine the optimal design aperture.

[0065] Preparation stage: Prepare a plurality of orifice plates 2 respectively, and each orifice plate 2 has a different aperture of the flow-through hole 3. Install these orifice plates 2 on the equalizing pipe body 1 respectively, ensure that the flow-through hole 3 of the orifice plate 2 is coaxially arranged with the equalizing pipe body 1, and then conduct a fluid flow simulation test.

[0066] Fluid flow simulation stage: Using computational fluid dynamics (CFD) software or other appropriate fluid flow simulation tools, set the boundary conditions under actual working conditions, such as inlet pressure, outlet pressure, flow velocity, etc. Conduct fluid flow simulation on the equalizing pipe body 1 with orifice plates of different orifice diameters, and record the axial force generated on the water turbine runner after the fluid passes through.

[0067] Data processing stage: Define the ratio of the through-hole diameter 3 of the orifice plate 2 to the inner diameter of the equalizing pipe body 1 as the relative diameter. Based on the minimum axial force among all test results in the fluid flow simulation stage, calculate the difference between the axial forces obtained in the other tests and the minimum axial force, and define the ratio of this difference to the minimum axial force as the relative axial force.

[0068] Stage of plotting the relationship curve: Based on the relative diameter and the corresponding relative axial force calculated above, plot the relative axial force - relative diameter relationship curve as shown in Figure 4 shown.

[0069] Determine the optimal orifice diameter: Find the inflection point area on the plotted relationship curve, that is, the place where the slope of the curve changes. The inflection point area usually represents the position where the performance changes most significantly. As shown in Figure 4 shown, the relative diameter corresponding to the inflection point area is 35% - 40% of the inner diameter of the equalizing pipe body 1. Take the orifice diameter value of the through-hole 3 corresponding to the inflection point area as the design orifice diameter, that is, the optimal orifice diameter. According to the determined design orifice diameter, select or manufacture the corresponding orifice plate 2 and apply it to the water turbine equalizing pipe to form the designed water turbine equalizing pipe.

[0070] In some other embodiments of the water turbine equalizing pipe design method provided by the present invention, as shown in Figure 5 shown, the steps for the orifice diameter 3 of the through-hole of the orifice plate 2 for designing the water turbine equalizing pipe include the following steps S10 - S50.

[0071] S10: Install the orifice plates 2 with different through-hole diameters 3 on the equalizing pipe body 1 respectively, and take the ratio of the through-hole diameter 3 of the orifice plate 2 to the inner diameter of the equalizing pipe body 1 as the relative diameter.

[0072] S20: Conduct water turbine fluid flow simulation on the equalizing pipe body 1 with orifice plates of different orifice diameters, record the main flow rate before the fluid passes through the equalizing pipe body 1 as the main flow rate, and take the difference between the flow rate after the fluid enters the gap cavity between the runner and the top cover and the main flow rate as the leakage flow rate.

[0073] S30: Based on the main flow rate, calculate the ratio of the leakage flow rate corresponding to the equalizing pipe body 1 with orifice plates of different orifice diameters to the main flow rate as the relative flow rate.

[0074] S40: Plot the relative flow rate - relative diameter relationship curve based on the relative diameter and the corresponding relative flow rate.

[0075] S50. Take the pore diameter value of the flow-through hole 3 corresponding to the inflection point region in the relative flow rate-relative diameter relationship curve as the design pore diameter, and take the water turbine equalizing pipe corresponding to the flow-through hole 3 with the design pore diameter as the design water turbine equalizing pipe.

[0076] It can be understood that the design method of the water turbine equalizing pipe in this embodiment is to record the influence of orifice plates with different pore diameters on the leakage flow rate through a series of fluid flow simulation experiments, and draw a relative flow rate-relative diameter relationship curve based on these data to determine the optimal design pore diameter.

[0077] Preparation stage: Prepare multiple orifice plates 2 respectively, and each orifice plate 2 has a flow-through hole 3 with a different pore diameter. Install these orifice plates 2 on the equalizing pipe body 1 respectively, ensure that the flow-through hole 3 of the orifice plate 2 is coaxially arranged with the equalizing pipe body 1, and then conduct a fluid flow simulation test.

[0078] Fluid flow simulation stage: Use computational fluid dynamics (CFD) software or other appropriate fluid flow simulation tools to set the boundary conditions under actual working conditions, such as inlet pressure, outlet pressure, flow velocity, etc. Record the flow rate of the fluid before passing through the equalizing pipe body, define it as the main flow rate, record the flow rate of the fluid after entering the clearance cavity between the runner and the top cover, and calculate the difference between it and the main flow rate as the leakage flow rate.

[0079] Data processing stage: Define the ratio of the pore diameter of the flow-through hole 3 of the orifice plate 2 to the inner diameter of the equalizing pipe body 1 as the relative diameter, and calculate the ratio of the leakage flow rate corresponding to the orifice plate 2 with different pore diameters to the main flow rate based on the main flow rate, and define it as the relative flow rate.

[0080] Drawing the relationship curve stage: Draw a relative flow rate-relative diameter relationship curve based on the relative diameter and the corresponding relative flow rate calculated above.

[0081] Determine the optimal pore diameter: Find the inflection point region on the drawn relationship curve, that is, the place where the slope of the curve changes. The inflection point region usually represents the position where the performance changes most significantly. See Figure 6 As shown, the relative diameter corresponding to the inflection point region is 35% - 40% of the inner diameter of the equalizing pipe body 1. Take the pore diameter value of the flow-through hole corresponding to the inflection point region as the design pore diameter, that is, the optimal pore diameter. According to the determined design pore diameter, select or manufacture the corresponding orifice plate 2 and apply it to the water turbine equalizing pipe to form the design water turbine equalizing pipe.

[0082] It can be understood that the design results of the above two design methods of the water turbine equalizing pipe provided in this embodiment can be mutually referred to and verified. Combining Figure 4 and Figure 6As shown, whether using the relative axial force-relative diameter relationship or the relative flow rate-relative diameter relationship, the optimal aperture of the flow-through hole 3 of the orifice plate 2 finally determined is 35% - 40% of the inner diameter of the pressure pipe body 1. Combining Figure 4 and Figure 6 it can be known that when the aperture of the flow-through hole 3 is 35% - 40% of the inner diameter of the pressure pipe body 1, it can effectively balance multiple factors affecting the stability of the unit, such as leakage flow rate, pressure loss, and axial force, effectively control the pressure and leakage volume in the upper crown seal cavity, and through the cooperation of the orifice plate 2 and the clearance of the anti-leakage ring, the characteristics of the clearance flow channel can be optimized. Although the influence on the overall axial force of the unit is small, by reducing the air supply volume, the risk of self-excited oscillation of the clearance flow can be indirectly reduced, while optimizing the pressure pulsation and noise level, reducing the energy consumption and water consumption of the unit during operation, so as to further improve the unit efficiency and system stability.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A turbine pressure equalizing pipe, characterized in that: The invention comprises a pressure equalizing tube body (1), wherein the pressure equalizing tube body (1) is provided with an orifice plate (2), wherein the orifice plate (2) is provided with a flow hole (3), wherein the flow hole (3) is coaxially arranged with the pressure equalizing tube body (1), and the inner diameter of the flow hole (3) is smaller than the tube diameter of the pressure equalizing tube body (1), so that when a fluid passes through the pressure equalizing tube body (1), a flow change occurs at the flow hole (3).

2. The turbine pressure equalizing pipe according to claim 1, characterized in that: The pressure equalizing tube body (1) comprises a first tube body (11) and a second tube body (12) of equal diameter; the orifice plate (2) is a circular orifice plate; and the first tube body (11), the orifice plate (2) and the second tube body (12) are detachably connected in sequence.

3. The turbine equalizing pipe according to claim 2, characterized in that: A first flange (13) is provided at the end of the first tube body (11), and a second flange (14) is provided at the end of the second tube body (12); the orifice plate (2) has a plurality of bolt holes distributed along the circumference, and the first flange (13), the orifice plate (2) and the second flange (14) are fastened together by bolts.

4. The turbine pressure equalizing pipe according to claim 3, characterized in that: A sealing member (4) is provided between the end surface opposite to the first flange member (13) and the orifice plate (2), and between the end surface opposite to the second flange member (14) and the orifice plate (2).

5. The turbine equalizing pipe according to claim 4, characterized in that: The first flange (13) and the second flange (14) are made of high carbon steel; The bolts used for fastening and connecting the first flange member (13), the orifice plate (2) and the second flange member (14) are hexagonal bolts made of high-strength stainless steel; The sealing member (4) is a polytetrafluoroethylene sealing ring, and a plurality of the sealing members (4) are distributed from the center to the periphery between the first flange member (13) and the end surface opposite to the orifice plate (2), and between the second flange member (14) and the end surface opposite to the orifice plate (2).

6. The turbine equalizing pipe according to any one of claims 1 to 5, characterized in that: The inner diameter of the flow hole (3) is 35% to 40% of the diameter of the pressure equalizing tube body (1).

7. A water turbine system, characterized in that: The invention comprises a turbine pressure equalizing pipe as described in any one of claims 1 to 6.

8. A method for designing a hydraulic turbine pressure equalizing pipe, characterized in that: The invention is applicable to the design of the turbine pressure equalizing pipe according to any one of claims 1 to 6, and the impedance of the turbine pressure equalizing pipe is adjusted by designing the diameter of the flow hole (3) of the orifice plate (2) of the turbine pressure equalizing pipe.

9. The method for designing a hydraulic turbine equalizing pipe according to claim 8, characterized in that: The aperture of the flow hole (3) of the orifice plate (2) of the turbine pressure equalizing pipe is designed to include: The orifice plates (2) with different diameters of the flow holes (3) are respectively installed on the pressure equalizing tube body (1), and the ratio of the diameter of the flow holes (3) of the orifice plates (2) to the inner diameter of the pressure equalizing tube body (1) is used as the relative diameter; Performing a turbine fluid flow simulation on the pressure-equalizing pipe body (1) equipped with orifice plates of different apertures, and recording the axial force generated by the turbine runner after the fluid passes through the pressure-equalizing pipe body (1) equipped with orifice plates of different apertures; Taking the minimum axial force among the axial forces generated by the turbine runner by the pressure equalizing pipe body (1) with orifice plates of different apertures as a reference, calculating the difference between the remaining axial forces and the minimum axial force, and taking the ratio of the difference to the minimum axial force as the relative axial force; Draw a relative axial force-relative diameter relationship curve based on the relative diameter and the corresponding relative axial force; The aperture value of the flow hole (3) corresponding to the inflection point region in the relative axial force-relative diameter relationship curve is taken as the design aperture, and the turbine equalizing pressure pipe corresponding to the flow hole (3) of the design aperture is taken as the design turbine equalizing pressure pipe.

10. The method for designing a hydraulic turbine equalizing pipe according to claim 8, characterized in that: The aperture of the flow hole (3) of the orifice plate (2) of the turbine pressure equalizing pipe is designed to include: The orifice plates (2) with different diameters of the flow holes (3) are respectively installed on the pressure equalizing tube body (1), and the ratio of the diameter of the flow holes (3) of the orifice plates (2) to the inner diameter of the pressure equalizing tube body (1) is used as the relative diameter; The flow simulation of the hydraulic turbine fluid is performed on the pressure equalizing pipe body (1) equipped with orifice plates of different apertures, the flow rate of the fluid before passing through the pressure equalizing pipe body (1) is recorded as the main flow rate, and the difference between the flow rate of the fluid after entering the gap cavity between the runner and the top cover and the main flow rate is taken as the leakage flow rate; Taking the main flow rate as a reference, calculating the ratio of the leakage flow rate corresponding to the pressure equalizing pipe body (1) with orifice plates of different apertures to the main flow rate as a relative flow rate; Draw a relative flow-relative diameter relationship curve based on the relative diameter and the corresponding relative flow; The aperture value of the flow hole (3) corresponding to the inflection point region in the relative flow-relative diameter relationship curve is taken as the design aperture, and the turbine equalizing pressure pipe corresponding to the flow hole (3) of the design aperture is taken as the design turbine equalizing pressure pipe.

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