Centrifugal pump

Abstract

The utility model relates to fluid conveying equipment technical field, concretely provides a centrifugal pump, and aims at solving the problem that the existing centrifugal pump is easy to cavitation when pumping high temperature liquid. For this purpose, the centrifugal pump of the utility model includes volute and the impeller arranged in the volute, the volute is equipped with the water outlet and the water outlet is connected with the water outlet pipe, the gradually expanding flow channel is formed in the water outlet pipe, and the cross section area of gradually expanding flow channel gradually increases along the liquid flow direction. Gradually expanding flow channel makes the flow velocity of liquid in flow channel gradually reduce, when the flow velocity reduces, the pressure energy of liquid can increase accordingly, thereby the pressure of liquid in water outlet pipe is not easy to reduce to below the saturated steam pressure corresponding to the high temperature liquid, effectively avoids the bubble generation of liquid vaporization, and further reduces the occurrence of cavitation phenomenon.

Description

TECHNICAL FIELD

[0001] The utility model relates to fluid conveying equipment technical field, concretely provides a centrifugal pump. BACKGROUND

[0002] Centrifugal pump is the fluid conveying equipment that is widely used in industrial and civil fields. However, when pumping high-temperature liquid (such as hot water, high-temperature process fluid), serious cavitation phenomenon is prone to occur in the pump, which becomes a long-standing technical bottleneck.

[0003] The root of cavitation problem lies in that liquid saturated vapor pressure significantly rises at high temperature. When the local pressure at the pump impeller inlet is lower than the liquid saturated vapor pressure at the temperature, the liquid will flash vaporization, and a large number of bubbles are generated. These bubbles move to the high-pressure area with the liquid flow, and instantaneously collapse, which produces strong local impact, that is, the cavitation process. Cavitation not only causes the sharp drop of pump flow and lift (manifested as 'cavitation rupture'), accompanied by vibration and noise, but also causes substantial erosion damage to the flow parts such as impeller and volute, which seriously affects the performance and service life of the pump.

[0004] To solve this problem, conventional technical means include: increasing pump inlet pressure (such as adding booster pump), reducing operating speed, using impeller with inducer or selecting cavitation-resistant material. However, these methods generally have limitations, they either increase system complexity and cost, or sacrifice the operating efficiency of the pump. Especially for compact structure, cost-sensitive small pump applications (such as water pump in household appliances), the above solutions cannot be implemented due to space limitations, or are difficult to be adopted due to economic considerations.

[0005] Therefore, there is a need in the art for a new technical solution to solve the above problems. SUMMARY

[0006] The utility model aims at solving the above technical problems, that is, solving the problem that the existing centrifugal pump is prone to cavitation when pumping high-temperature liquid.

[0007] The utility model provides a centrifugal pump, including volute and impeller that are arranged in the volute, the volute is equipped with water outlet and the water outlet is connected with water outlet pipe, the gradually expanding flow channel is formed in the water outlet pipe, and the cross-sectional area of the gradually expanding flow channel gradually increases along the liquid outflow direction.

[0008] In the preferred technical scheme of the above centrifugal pump, the impeller includes front cover plate, rear cover plate and a plurality of blades arranged between the front cover plate and the rear cover plate, and the height H of the front cover plate and the rear cover plate ranges from 0.8 mm to 1.5 mm.

[0009] In the preferred technical scheme of the centrifugal pump, the gradually expanding flow channel is a conical flow channel, one end of the gradually expanding flow channel close to the impeller is a small diameter end, one end of the gradually expanding flow channel far from the impeller is a large diameter end, and the diameter of the small diameter end is smaller than the diameter of the large diameter end.

[0010] In the preferred technical scheme of the centrifugal pump, the diameter of the large diameter end is greater than or equal to the diameter of the water outlet.

[0011] In the preferred technical scheme of the centrifugal pump, the diameter of the small diameter end is 80% to 90% of the diameter of the water outlet.

[0012] In the preferred technical scheme of the centrifugal pump, the included angle between the conical generatrix of the gradually expanding flow channel and the axis of the gradually expanding flow channel forms a diffusion angle, and the diffusion angle ranges from 5° to 15°.

[0013] In the preferred technical scheme of the centrifugal pump, the inner wall of the gradually expanding flow channel is circumferentially provided with a plurality of flow guide fins, and the height of the flow guide fins gradually increases along the liquid outflow direction.

[0014] In the preferred technical scheme of the centrifugal pump, the gradually expanding flow channel is a linear conical or a curved horn-shaped.

[0015] In the preferred technical scheme of the centrifugal pump, the surface of the blade is coated with a hydrophobic coating, and the coating thickness of the hydrophobic coating is 200-300 μm.

[0016] In the preferred technical scheme of the centrifugal pump, the water outlet pipe and the volute are integrally formed, or The water outlet pipe and the volute are detachably fixedly connected.

[0017] As can be understood by those skilled in the art, the technical scheme of the utility model provides a centrifugal pump, which comprises a volute and an impeller arranged in the volute, the volute is provided with a water outlet and a water outlet pipe connected to the water outlet, a gradually expanding flow channel is formed in the water outlet pipe, and the cross-sectional area of the gradually expanding flow channel gradually increases along the liquid outflow direction. In the case of adopting the above technical scheme, the utility model can effectively solve the problem that cavitation is prone to occur when the centrifugal pump pumps high-temperature liquid. Specifically, the gradually expanding flow channel is arranged in the water outlet pipe, the flow rate of the liquid in the flow channel gradually decreases, the pressure energy of the liquid correspondingly increases when the flow rate decreases, so that the pressure of the liquid in the water outlet pipe is not easily reduced to below the corresponding saturated steam pressure of the high-temperature liquid, the liquid vaporization and the generation of bubbles are effectively avoided, and the occurrence of cavitation is reduced.

[0018] Further, the impeller of the utility model includes front cover plate, back cover plate and multiple blades arranged between the front cover plate and the back cover plate, the height H of the front cover plate and the back cover plate ranges from 0.8mm to 1.5mm. When the height ranges from 0.8mm to 1.5mm, the liquid flows more smoothly between the blades, reduces the adverse phenomena such as flow separation, vortex and the like caused by improper cover plate height, can make the liquid more evenly distributed when entering the impeller, reduces the generation of local low pressure area, thereby reducing the possibility of cavitation.

[0019] Further, the utility model discloses the conical flow passage, the one end of conical flow passage near the impeller is small diameter end, the one end of conical flow passage far from the impeller is big diameter end, and the diameter of small diameter end is less than the diameter of big diameter end. The conical conical flow passage reduces liquid flow rate, and according to Bernoulli equation, under the condition of energy conservation, the flow rate reduction will make the pressure of liquid correspondingly increase. This makes the pressure of liquid in the outlet pipe not easy to reduce below the saturation vapor pressure corresponding to the high-temperature liquid, thereby effectively avoiding the bubble generation of liquid vaporization and reducing the occurrence of cavitation.

[0020] Further, the included angle between the conical generatrix of the utility model and the axis of the conical flow passage constitutes the diffusion angle, and the range of the diffusion angle is 5° to 15°. When the diffusion angle ranges from 5° to 15°, the liquid flows stably, the pressure distribution is uniform, and the possibility of cavitation can be further reduced. BRIEF DESCRIPTION OF DRAWINGS

[0021] The preferred embodiments of the utility model are described below in combination with the drawings, and the drawings are as follows: Fig. 1 It is the structure schematic diagram of centrifugal pump of the utility model; Fig. 2 It is the structure schematic diagram of impeller of the utility model; Fig. 3 It is the sectional view of centrifugal pump of the utility model.

[0022] LIST OF REFERENCE NUMERALS 1, volute; 11, water outlet; 2, impeller; 21, front cover plate; 22, back cover plate; 23, blade; 3, outlet pipe; 31, conical flow passage. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application. For example, although the following embodiments are introduced in combination with a small centrifugal pump, the centrifugal pump provided by the present application is also applicable to other products which need to solve the problem of cavitation erosion of the centrifugal pump when pumping high-temperature liquid.

[0024] It should be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms "arranged", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or detachably connected, or integrally connected. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0025] Based on the problem of cavitation erosion of the existing centrifugal pump when pumping high-temperature liquid pointed out in the background art. The present application provides a centrifugal pump, which aims to effectively solve the problem of cavitation erosion of the centrifugal pump when pumping high-temperature liquid by arranging the flow channel of the outlet of the centrifugal pump into a gradually expanding conical flow channel and reducing the height between the front cover plate and the rear cover plate of the impeller.

[0026] As shown in Figs. 1 to 3 The present application provides a centrifugal pump, which comprises a volute 1 and an impeller 2 arranged inside the volute 1. The volute 1 is provided with a water outlet 11, and the water outlet 11 is communicated with a water outlet pipe 3. A gradually expanding flow channel 31 is formed in the water outlet pipe 3, and the cross-sectional area of the gradually expanding flow channel 31 gradually increases along the liquid outflow direction.

[0027] The volute 1 is an important housing component of the centrifugal pump, which functions to collect the liquid thrown out by the impeller 2 and guide the liquid to flow in a certain direction, and finally deliver the liquid to the water outlet pipe 3.

[0028] The impeller 2 is arranged inside the volute 1 and is the core working component of the centrifugal pump. When the impeller 2 rotates at high speed under the drive of the motor, the blades 23 on the impeller 2 will exert force on the liquid, so that the liquid obtains energy and generates centrifugal force, which throws the liquid from the center of the impeller 2 to the outer edge of the impeller 2.

[0029] The volute 1 is provided with a water outlet 11, which is a passage for the liquid to flow from the inside of the volute 1 to the outside pipe, and is a key outlet part for the centrifugal pump to realize the liquid delivery function. The water outlet 11 is communicated with a water outlet pipe 3, which is an important component connecting the centrifugal pump and the subsequent conveying pipeline, and is responsible for further conveying the liquid flowing out of the volute 1 to the designated use location or the next level of processing equipment.

[0030] This invention features a gradually expanding flow channel 31 within the outlet pipe 3. This means that the shape of the channel inside the outlet pipe 3 is not uniform, but rather the cross-sectional area gradually increases along the liquid outflow direction. This specially designed flow channel structure is intended to alter the flow state of the liquid within the outlet pipe 3.

[0031] When a centrifugal pump pumps a high-temperature liquid, the pressure of the liquid in the outlet pipe 3 gradually decreases with the flow. A gradually expanding flow channel 31 is used; since the cross-sectional area of ​​the channel gradually increases along the liquid outflow direction, according to fluid mechanics principles, the liquid velocity within the channel gradually decreases. According to Bernoulli's equation, in an incompressible, inviscid, steady-state ideal fluid, the total energy of the fluid (including pressure energy, kinetic energy, and potential energy) remains constant. When the flow velocity decreases, the pressure energy of the liquid increases accordingly, thus preventing the pressure of the liquid in the outlet pipe 3 from falling below the saturated vapor pressure corresponding to the high-temperature liquid. This effectively avoids the formation of bubbles through liquid vaporization, thereby reducing cavitation.

[0032] Cavitation can cause severe impact and wear on the impeller 2, volute 1, and other flow-through components of a centrifugal pump, leading to a decline in pump performance, such as reduced flow rate, reduced head, and reduced efficiency. This invention reduces cavitation by minimizing its impact on flow-through components, enabling the centrifugal pump to operate stably for extended periods, maintaining high performance indicators, extending its service life, and reducing equipment maintenance and replacement costs.

[0033] Preferably, such as Fig. 2 As shown, the impeller 2 includes a front cover plate 21, a rear cover plate 22, and a plurality of blades 23 disposed between the front cover plate 21 and the rear cover plate 22. The height H of the front cover plate 21 and the rear cover plate 22 ranges from 0.8 mm to 1.5 mm.

[0034] The impeller 2, as the core component of the centrifugal pump, is composed of a front cover plate 21, a rear cover plate 22, and multiple blades 23 located between them. The front cover plate 21 and the rear cover plate 22 serve to support and fix the blades 23, and together with the blades 23, they form a specific fluid channel to guide the liquid to flow in a specific manner and obtain energy.

[0035] The front cover plate 21 is located on the side of the impeller 2 closest to the liquid inflow. It can guide the liquid entering the impeller 2 to flow evenly to each blade 23, so that the liquid forms a relatively stable flow state at the inlet of the impeller 2, reducing flow loss and improving the suction performance of the impeller 2.

[0036] The rear cover plate 22 is located on the side of the impeller 2 closest to the liquid outflow. It works in conjunction with the front cover plate 21 to constrain the flow path of the liquid between the blades 23, prevent backflow and other adverse flow phenomena in the impeller 2, and ensure that the liquid can efficiently obtain energy from the impeller 2 and flow out smoothly.

[0037] The blades 23 are arranged between the front cover plate 21 and the rear cover plate 22, and are the key part of the impeller 2 to do work on the liquid. When the impeller 2 rotates, the blades 23 exert force on the liquid, increasing the speed and pressure of the liquid, thereby realizing the conversion of mechanical energy into pressure energy and kinetic energy of the liquid.

[0038] The height H of the front cover plate 21 and the rear cover plate 22 is 0.8mm to 1.5mm, which can optimize the fluid flow state inside the impeller 2. When the height is 0.8mm to 1.5mm, the liquid flows more smoothly between the blades 23, reducing the adverse phenomena such as flow separation and vortex caused by inappropriate cover plate height. These adverse flows will increase the energy loss of the liquid and reduce the efficiency of the impeller 2. The optimized cover plate height can reduce these losses, so that the impeller 2 can more efficiently transfer mechanical energy to the liquid and improve the overall efficiency of the centrifugal pump.

[0039] In addition, the front cover plate 21 and the rear cover plate 22 with reasonable height help to improve the pressure distribution at the inlet of the impeller 2. When the cover plate height is in the range of 0.8mm to 1.5mm, the liquid can be more evenly distributed when entering the impeller 2, reducing the generation of local low pressure area. As mentioned earlier, local low pressure area is one of the important factors that cause cavitation. By optimizing the cover plate height, the possibility of cavitation is reduced, thereby improving the reliability and service life of the centrifugal pump when pumping liquid, especially high temperature liquid.

[0040] Preferably, as shown in Fig. 3 The gradually expanding flow channel 31 is a conical flow channel, the gradually expanding flow channel 31 is close to the small diameter end of the impeller 2, the gradually expanding flow channel 31 is far away from the large diameter end of the impeller 2, and the diameter of the small diameter end is smaller than the diameter of the large diameter end.

[0041] When the liquid flows out of the impeller 2 and enters the conical gradually expanding flow channel 31, due to the gradual increase of the cross-sectional area of the flow channel, according to the continuity equation of fluid mechanics (in the stable flow of incompressible fluid, the fluid volume passing through any cross section of the flow channel per unit time is equal), the flow velocity of the liquid will gradually decrease. The decrease of flow velocity helps to reduce the kinetic energy loss of the liquid during flow, so that more energy exists in the form of pressure energy, thereby improving the lift and efficiency of the centrifugal pump.

[0042] The conical shape of the flow channel allows the liquid to conform more smoothly to the channel wall during flow, reducing flow separation. Flow separation refers to the phenomenon where, during flow, some liquid detaches from the channel wall due to friction and pressure gradients, forming a backflow zone within the channel. This backflow zone increases flow resistance and reduces pump efficiency. Flow separation can also cause eddies within the channel, increasing energy loss and degrading pump performance. The smooth transition of the conical flow channel guides the liquid to flow steadily, reducing the likelihood of flow separation and improving flow efficiency.

[0043] Furthermore, the conical, gradually expanding flow channel 31 reduces the liquid flow velocity. According to Bernoulli's equation, under the condition of energy conservation, a decrease in flow velocity will correspondingly increase the liquid pressure. This makes it less likely for the liquid pressure in the outlet pipe 3 to drop below the saturated vapor pressure corresponding to the high-temperature liquid, thereby effectively preventing liquid vaporization and the generation of bubbles, reducing cavitation, and extending the service life of the centrifugal pump.

[0044] Furthermore, as the liquid flows within the channel, it experiences friction and local resistance from the channel walls, resulting in pressure loss. The design of the conical, gradually expanding channel 31 enables more uniform and stable liquid flow, reducing local resistance caused by abrupt changes in channel shape. Simultaneously, the gradual decrease in flow velocity reduces friction between the liquid and the channel walls, thereby reducing pressure loss within the outlet pipe 3 and improving the energy efficiency of the centrifugal pump.

[0045] Preferably, the diameter of the large-diameter end is greater than or equal to the diameter of the outlet 11.

[0046] When the diameter of the large-diameter end is greater than or equal to the diameter of the outlet 11, the continuity of liquid flow from the outlet 11 of the volute 1 into the outlet pipe 3 can be guaranteed. If the diameter of the large-diameter end is smaller than the diameter of the outlet 11, the liquid will suddenly encounter cross-sectional contraction when entering the outlet pipe 3 from the outlet 11, resulting in local flow turbulence and energy loss, just like water flow suddenly being blocked at a narrow point, resulting in rapid water flow and increased energy dissipation. However, when the diameter of the large-diameter end is greater than or equal to the diameter of the outlet 11, the liquid can smoothly transition from the outlet 11 to the outlet pipe 3, reducing abrupt changes in flow, making the liquid flow more smoothly, reducing energy loss caused by flow discontinuity, and improving the efficiency of the centrifugal pump.

[0047] During liquid flow, sudden changes in cross-section can cause pressure fluctuations and losses. When the diameter of the large-diameter end is greater than or equal to the diameter of the outlet 11, the sharp drop in pressure and the formation of local high-pressure zones caused by cross-sectional contraction when the liquid enters the outlet pipe 3 are avoided. This smooth transition allows for a more uniform pressure distribution of the liquid, reduces pressure loss, and enables more energy to be used for liquid transport, thereby improving the head and transport capacity of the centrifugal pump.

[0048] Furthermore, when the diameter of the large-diameter end is greater than or equal to the diameter of the outlet 11, the pressure of the liquid in the outlet pipe 3 can be kept relatively stable, preventing the liquid from vaporizing and generating bubbles due to excessively low pressure caused by cross-sectional contraction. Especially when pumping high-temperature liquids, the liquid itself is prone to vaporization due to pressure reduction. A reasonable diameter relationship can further reduce this risk, protect the flow-through components of the centrifugal pump from cavitation damage, and extend the service life of the pump.

[0049] Preferably, the diameter of the smaller diameter end is 80% to 90% of the diameter of the outlet 11.

[0050] When the diameter of the smaller diameter end is 80% to 90% of the diameter of the outlet 11, the liquid will not experience a sudden change in diameter when flowing from the outlet 11 of the volute 1 into the smaller diameter end of the outlet pipe 3. If the diameter of the smaller diameter end is too small, for example, much smaller than 80% of the diameter of the outlet 11, the liquid will suddenly contract when entering the outlet pipe 3, generating a strong flow impact and forming a high-speed jet, leading to increased energy loss. It will also induce eddies and turbulence within the outlet pipe 3, making the liquid flow unstable. Within this preferred ratio range, the liquid can flow into the outlet pipe 3 more smoothly from the smaller diameter end, reducing flow impact and energy loss.

[0051] If the small-diameter end diameter is too large, approaching or exceeding 90% of the outlet diameter 11, the liquid may not flow smoothly along the wall when entering the outlet pipe 3, easily causing flow separation at the corner. Flow separation creates a low-speed backflow zone, increasing flow resistance and reducing pump efficiency.

[0052] Furthermore, the centrifugal pump's function is to convert mechanical energy into the pressure and kinetic energy of the liquid. After gaining energy from the impeller 2, the liquid collects and distributes energy within the volute 1, and then enters the outlet pipe 3 through the outlet 11. A suitable ratio between the small-diameter end diameter and the outlet 11 diameter allows the liquid to convert more kinetic energy into pressure energy as it enters the outlet pipe 3. In the gradually expanding flow channel 31, as the channel diameter gradually increases, the liquid velocity gradually decreases, and the pressure gradually increases. When the small-diameter end diameter is 80% to 90% of the outlet 11 diameter, it provides a favorable starting condition for this energy conversion, making the energy conversion process more efficient, thereby improving the centrifugal pump's head and efficiency.

[0053] Preferably, the angle between the tapered generatrix of the gradually expanding flow channel 31 and the axis of the gradually expanding flow channel 31 constitutes a diffusion angle, which ranges from 5° to 15°.

[0054] When the diffusion angle is between 5° and 15°, the cross-sectional area of ​​the gradually expanding channel 31 changes relatively smoothly. As the liquid flows within the channel, the velocity reduction process is more uniform, resulting in a smaller velocity gradient. A smaller velocity gradient reduces shear stress within the liquid, decreases eddies and turbulence caused by uneven velocity, and makes the liquid flow more stable. For example, if the diffusion angle is too large, the cross-sectional area of ​​the channel changes drastically, and the liquid velocity will decrease significantly in a short time, easily forming strong eddies within the channel and increasing energy loss; while if the diffusion angle is too small and the channel is too long, although the velocity reduction is uniform, it will increase the cost and floor space of the equipment.

[0055] A suitable diffusion angle allows the liquid to flow better along the channel wall, avoiding flow separation. When the diffusion angle is between 5° and 15°, the liquid can flow smoothly along the wall, reducing the possibility of flow separation and improving the flow efficiency of the liquid.

[0056] Cavitation occurs when liquid pressure drops below saturated vapor pressure, causing bubbles to form. These bubbles can then burst and damage flow components. A suitable diffusion angle maintains relatively stable liquid pressure within the diffuser channel 31, preventing excessively low pressure from causing vaporization and bubble formation. When the diffusion angle is between 5° and 15°, the liquid flow is smooth and the pressure distribution is uniform, reducing the likelihood of cavitation, protecting the centrifugal pump's flow components from cavitation damage, and extending the pump's service life.

[0057] Preferably, the inner wall of the gradually expanding flow channel 31 is evenly distributed with multiple guide fins (not shown in the figure), and the height of the guide fins gradually increases along the liquid outflow direction.

[0058] In the gradually expanding flow channel 31, the liquid is prone to generating eddies and secondary flows near the wall due to the increased cross-sectional area of ​​the channel. These unstable flows increase the energy loss of the liquid and reduce the efficiency of the pump. Circumferentially distributed guide fins can interfere with and disrupt the formation of eddies and secondary flows. As the liquid flows, the guide fins, whose height gradually increases, can more effectively guide the liquid flow, allowing it to flow more smoothly along the center of the channel, reducing turbulent flow near the wall, and thus reducing energy loss.

[0059] Furthermore, the uniform distribution of the guide fins ensures relatively consistent liquid flow in all circumferential directions of the flow channel. The gradually increasing height of the design further adjusts the flow velocity and direction of the liquid at different locations, resulting in even more uniform flow throughout the entire channel. Uniform flow contributes to improved pump stability and reliability, reducing vibration and noise caused by uneven flow.

[0060] Furthermore, the guide fins can better guide the liquid to adapt to changes in the cross-sectional area of ​​the flow channel, allowing the liquid to decelerate more orderly during flow, thereby more effectively converting kinetic energy into pressure energy. Guide fins with gradually increasing height can provide more precise guidance based on changes in liquid flow velocity, further improving energy conversion efficiency.

[0061] The guide fins, installed on the inner wall of the gradually expanding flow channel 31, also provide some support. During liquid flow, the inner wall of the flow channel is subjected to liquid pressure and impact forces. The guide fins can disperse these forces, enhance the structural strength of the inner wall of the flow channel, reduce flow channel deformation and damage caused by liquid pressure and impact forces, and improve the service life of the flow channel.

[0062] Preferably, the gradually expanding flow channel 31 is a straight conical shape or a curved trumpet shape.

[0063] The straight conical gradually expanding flow channel 31 refers to a flow channel whose generatrix is ​​a straight line, and the entire flow channel presents a regular conical shape. From the inlet (small diameter end) to the outlet (large diameter end) of the flow channel, its diameter gradually increases according to a linear law, that is, the cross-sectional area of ​​the flow channel expands uniformly along the direction of liquid flow.

[0064] When liquid flows in the straight conical expanding flow channel 31, the liquid can adapt relatively smoothly to changes in the flow channel cross-sectional area. Compared with some complex-shaped flow channels, the straight conical flow channel has a smoother wall surface without obvious abrupt changes or turns, reducing friction and collisions between the liquid and the wall, thereby reducing flow resistance. This helps to improve the flow efficiency of the liquid, reduce energy loss, and enable the centrifugal pump to be more energy-efficient when transporting liquids.

[0065] The generatrix of the curved funnel-shaped gradually expanding flow channel 31 is curved, resembling a funnel mouth, but the curvature of the curve is not constant. The diameter of the flow channel does not change uniformly, but gradually increases according to a specific curve law, making the expansion process of the cross-sectional area of ​​the flow channel more gradual or conforming to specific fluid dynamic requirements.

[0066] The curved, flared, gradually expanding flow channel 31 allows liquids or gases to flow more closely to the channel wall, reducing flow separation. Flow separation refers to the phenomenon where, during fluid flow, some fluid detaches from the channel wall due to friction and pressure gradients, forming a backflow zone within the channel. Backflow zones increase flow resistance, reduce equipment efficiency, and may cause vibration and noise problems. The curved, flared flow channel, through its optimized curve design, allows the fluid to gradually slow down and diffuse within the channel, avoiding abrupt changes in velocity and pressure gradients, thereby reducing flow separation and improving the quality of fluid flow. Preferably, the surface of the blade 23 is coated with a hydrophobic coating, and the coating thickness is 200-300 μm.

[0067] The hydrophobic coating reduces liquid adhesion to the surface of the blades 23, allowing the liquid to flow more smoothly across them and reducing pressure fluctuations on the blade surface. This effectively reduces cavitation and extends the service life of the blades 23 and the entire centrifugal pump. Furthermore, because the hydrophobic coating reduces friction and adhesion between the liquid and the blade surface, the flow resistance within the impeller 2 is reduced, thereby improving the efficiency of the centrifugal pump and reducing energy consumption.

[0068] Preferably, the water outlet pipe 3 and the volute 1 are integrally formed, or the water outlet pipe 3 and the volute 1 are detachably and fixedly connected.

[0069] When the outlet pipe 3 and the volute 1 are manufactured using an integral molding process, the outlet pipe 3 and the volute 1 become a single unit. When subjected to liquid pressure, vibrations generated by the impeller 2's rotation, and external mechanical forces, they can share the stress, resulting in a more robust and durable overall structure. Compared to a split structure, integrally molded components are less prone to loosening or breakage at connection points during long-term operation, thus improving the reliability and service life of the centrifugal pump.

[0070] When the outlet pipe 3 and the volute 1 are connected by a detachable fixed connection, the damaged parts can be easily disassembled for repair or replacement without replacing the entire centrifugal pump, which greatly reduces maintenance costs and time. Furthermore, the outlet pipe 3 of different specifications or materials can be flexibly replaced according to actual working conditions, enabling the centrifugal pump to better adapt to various complex working environments.

[0071] For example, the water outlet pipe 3 and the volute 1 can be detachably connected by means of flange connection, threaded connection, clamp connection, etc. This utility model does not specifically limit the specific connection form of the detachable connection.

[0072] The technical solution of this utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A centrifugal pump, characterized in that, It includes a volute (1) and an impeller (2) disposed inside the volute (1). The volute (1) is provided with a water outlet (11) and the water outlet (11) is connected to a water outlet pipe (3). A gradually expanding flow channel (31) is formed inside the water outlet pipe (3), and the cross-sectional area of ​​the gradually expanding flow channel (31) gradually increases along the liquid outflow direction.

2. The centrifugal pump according to claim 1, characterized in that, The impeller (2) includes a front cover plate (21), a rear cover plate (22), and a plurality of blades (23) disposed between the front cover plate (21) and the rear cover plate (22). The height H of the front cover plate (21) and the rear cover plate (22) ranges from 0.8 mm to 1.5 mm.

3. The centrifugal pump according to claim 1, characterized in that, The gradually expanding flow channel (31) is a conical flow channel. The end of the gradually expanding flow channel (31) closer to the impeller (2) is the small diameter end, and the end of the gradually expanding flow channel (31) farther away from the impeller (2) is the large diameter end. The diameter of the small diameter end is smaller than the diameter of the large diameter end.

4. The centrifugal pump according to claim 3, characterized in that, The diameter of the large-diameter end is greater than or equal to the diameter of the outlet (11).

5. The centrifugal pump according to claim 3, characterized in that, The diameter of the smaller diameter end is 80% to 90% of the diameter of the outlet (11).

6. The centrifugal pump according to claim 3, characterized in that, The angle between the tapered generatrix of the gradually expanding flow channel (31) and the axis of the gradually expanding flow channel (31) constitutes a diffusion angle, which ranges from 5° to 15°.

7. The centrifugal pump according to claim 3, characterized in that, The inner wall of the gradually expanding flow channel (31) is evenly distributed with multiple guide fins, and the height of the guide fins gradually increases along the liquid outflow direction.

8. The centrifugal pump according to claim 3, characterized in that, The gradually expanding flow channel (31) is a straight cone shape or a curved flared shape.

9. The centrifugal pump according to claim 2, characterized in that, The surface of the blade (23) is coated with a hydrophobic coating, and the coating thickness is 200-300 μm.

10. The centrifugal pump according to any one of claims 1 to 9, characterized in that, The water outlet pipe (3) is integrally formed with the volute (1), or The water outlet pipe (3) is detachably and fixedly connected to the volute (1).

Images