Reversible pump turbine

Abstract

The invention relates to the technical field of microminiature pump turbines, and discloses a reversible pump turbine which comprises a shell, a double-suction impeller and a guide vane, the shell comprises a volute and a flow guide shell, the volute is provided with a spiral nest cavity, the center of the volute is provided with a mounting groove communicated with the nest cavity, the flow guide shell wraps the left side and the right side of the volute in a Y shape, and the double-suction impeller is arranged in the mounting groove. Semi-spiral flow guide cavities are symmetrically formed in the flow guide shell, the two flow guide cavities communicate with the mounting groove, a mounting hole is formed in the flow guide shell in a penetrating mode, the axis of the mounting hole coincides with rotating shafts of the nest cavities and the flow guide cavities, a rotating shaft is arranged in the mounting hole, the double-suction impeller is arranged on the outer wall of the rotating shaft, and a plurality of blades are arranged on the outer walls of the two sides of the double-suction impeller in a staggered mode. The guide vane is arranged in the mounting groove, and the double-suction impeller is located in the guide vane; under the working condition of the pump, water flow can be evenly and smoothly introduced into the double-suction impeller through the flow guide cavity, and flow field disorder and rotational flow loss caused by single-side water suction are avoided; under the working condition of the water turbine, the flow guide cavity can smoothly guide water flow.

Description

Technical Field

[0001] This invention relates to the field of micro-sized water pump turbine technology, and more specifically to a reversible water pump turbine. Background Technology

[0002] As the core energy conversion equipment of pumped storage power stations, pump-turbines can switch between pump and turbine modes. During periods of low load, they convert electrical energy into water potential energy for storage, and during periods of high load, they release water potential energy and convert it into electrical energy. They are key components for ensuring the stable and efficient operation of power systems. This equipment is widely used in various fields such as hydropower, agricultural irrigation, urban water supply, and power grid peak shaving. It can adapt to the fluctuating energy replenishment needs of new energy power stations while ensuring the stable operation of power systems. It has core advantages such as high efficiency, energy saving, and flexible switching between operating modes.

[0003] However, the guide chambers of existing pump-turbines mostly adopt straight cylindrical or simple arc-shaped structures, which can only adapt to a single operating condition. Under pump conditions, the water flow is uneven and prone to swirling. Under turbine conditions, the tailwater is not discharged smoothly and there is backflow loss. Moreover, the double-suction impellers of existing pump-turbines mostly adopt a back-to-back double-suction structure with unreasonable blade arrangement, resulting in large pressure pulsation and serious hydraulic loss during operation, and poor unit stability. To address these issues, we propose a reversible pump-turbine to solve the above problems. Summary of the Invention

[0004] The present invention aims to provide a reversible pump-turbine to solve the problems of uneven water flow introduction and easy generation of vortex flow in existing pump-turbines under pump operation, and poor tailwater discharge and backflow loss under turbine operation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a reversible water pump turbine, comprising a casing, a double-suction impeller, and guide vanes. The casing includes a volute and a guide shell. The volute has a spiral cavity, and a mounting groove communicating with the cavity is formed in the center of the volute. The guide shell is Y-shaped and wraps around the left and right sides of the volute. Spiral guide cavities are symmetrically formed inside the guide shell, and both guide cavities are communicating with the mounting groove. A mounting hole is formed through the guide shell, and the axis of the mounting hole coincides with the rotation axis of the cavity and the guide cavity. A rotating shaft is provided in the mounting hole. The double-suction impeller is located on the outer wall of the rotating shaft. Several blades are alternately arranged on the outer walls of the two sides of the double-suction impeller. The guide vanes are located in the mounting groove, and the double-suction impeller is located inside the guide vanes.

[0006] The beneficial effects of this design are as follows: the guide shell symmetrically wraps around both sides of the volute, with symmetrically arranged spiral guide cavities inside. Both guide cavities are connected to the mounting groove, forming a smooth two-way flow channel system in conjunction with the spiral recess in the volute's pressure pipe. In pump operation, the guide cavity acts as the suction chamber, and the volute as the pressure chamber. The guide cavity can evenly and smoothly introduce water into the double-suction impeller, avoiding flow field turbulence and vortex losses caused by unilateral suction. In turbine operation, the volute acts as the suction chamber, and the guide cavity as the pressure chamber. The guide cavity can smoothly discharge water, eliminating backflow vortices. The concave cavity enables stable water flow collection and transportation, significantly improving the flow channel efficiency. The staggered arrangement of the blades on both sides of the double-suction impeller effectively counteracts the impact of water flow on the blades during operation, reducing blade vibration and water flow pulsation, and improving the stability of unit operation. At the same time, in pump mode, the guide vanes can rectify the water flow at the outlet of the double-suction impeller, optimize the flow field distribution, and avoid water flow impact losses. In turbine mode, it can guide the water flow to form a reasonable pre-swirl, providing sufficient circulation for the double-suction impeller to perform efficient work, and taking into account the energy conversion efficiency in both bidirectional operation modes.

[0007] Preferably, as an improvement, the spiral profile is set as an Archimedean spiral, and the flow guide cavity is set as a semi-spiral shape.

[0008] Preferably, as an improvement, several blades are inclinedly disposed on the outer wall of the double-suction impeller, and the inclination angle of the blades is set to θ1, where θ1 = 360° / (2 Z1), where Z1 is the number of blades on one side of the double-suction impeller.

[0009] The beneficial effects are as follows: the inclined arrangement of the blades can optimize the angle of water flow in and out of the double suction impeller, reduce water flow impact and flow separation, reduce hydraulic loss on the blade surface, and at the same time, in conjunction with the staggered arrangement of the blades, further offset the impact force of water flow pulsation and improve the stability of unit operation.

[0010] Preferably, as an improvement, the number of guide vanes is set to Z2, and Z2 = X2. Z1, where Z1 and Z2 are coprime numbers and cannot have a common divisor, and X2 takes values ​​from 1.2 to 1.6.

[0011] The beneficial effects are as follows: Z2 and Z1 are coprime numbers, which can avoid the two from generating a resonance frequency and avoid periodic disturbance of water flow in the flow channel. The reasonable range of X2 ensures that the guide vane density is adapted to the blade layout of the double suction impeller, which can give full play to the rectification and guiding effect of the guide vanes, and will not increase hydraulic resistance due to excessively dense guide vanes, thus significantly improving the stability of unit operation.

[0012] Preferably, as an improvement, the guide vane placement angle is set to 10-15°.

[0013] The beneficial effects are as follows: a placement angle of 10-15° can accurately rectify the turbulent water flow at the outlet of the double-suction impeller under pump conditions, guiding the water flow smoothly to the cavity along the flow channel, avoiding problems such as insufficient rectification and flow field distortion caused by too small a placement angle, or a surge in flow channel resistance and hydraulic loss caused by too large a placement angle; under turbine conditions, it can provide reasonable pre-swirl for the water flow entering the double-suction impeller, ensuring that the water flow impacts the blades of the double-suction impeller at the optimal angle, providing sufficient circulation for the double-suction impeller to work efficiently.

[0014] Preferably, as an improvement, the wrap angle of the guide vane is set to θ3, and θ3 = X3. θ2, where θ2 is the wrap angle of the blades on the outer wall of the double suction impeller, and X3 ranges from 0.25 to 0.5.

[0015] The beneficial effects are as follows: Setting the value of X3 within the range of 0.25-0.5 allows the guide vane wrap angle θ3 to be precisely matched with the double-suction impeller blade wrap angle θ2, ensuring that the water flow from the double-suction impeller outlet can smoothly transition along the guide vane channel under pump operating conditions. This avoids problems such as excessively long channel and increased water flow friction loss due to an excessively large guide vane wrap angle, or excessively short channel and excessively rapid diffusion due to an excessively small wrap angle, which can cause flow separation vortices. At the same time, selecting a reasonable guide vane wrap angle can optimize the cross-sectional shape of the guide vane channel, making the flow trajectory and velocity distribution of the water in the guide vane area more uniform, minimizing local hydraulic losses, and improving the flow efficiency of the channel.

[0016] Preferably, as an improvement, the radial clearance between the blade and the guide vane is set to H, and H = X1. D1, where D1 is the outlet diameter of the double suction impeller, and X1 ranges from 0.03 to 0.06.

[0017] The beneficial effects are as follows: Under pump operation, the reasonable radial clearance can provide a buffer transition space for the high-speed water flow at the outlet of the double-suction impeller, avoid the water flow directly impacting the guide vane inlet, and ensure that the water flow smoothly enters the guide vane rectification area after being pressurized by the double-suction impeller; Under turbine operation, it can reduce the backflow interference of the water flow at the outlet of the guide vane to the inlet of the double-suction impeller, and ensure that the water flow enters the double-suction impeller at a stable angle to do work.

[0018] Preferably, as an improvement, the inlet diameter and inlet width of the cavity are equal to the outlet diameter and outlet width of the guide vane, respectively. This allows the water flow from the guide vane outlet to smoothly enter the cavity without abrupt changes or steps, completely avoiding problems such as abrupt changes in the flow channel cross-section and flow deflection caused by size mismatch. It also reduces impact loss, eddy current loss, and local resistance loss in the connection area, ensuring the continuity and smoothness of the water flow and significantly improving the overall flow efficiency of the flow channel. Under pump operation, the uniform water flow after being rectified by the guide vane can directly and smoothly enter the cavity, avoiding flow field distortion caused by size deviation and ensuring that the cavity efficiently completes water flow collection and pressurization. Under turbine operation, the water flow introduced into the cavity can be evenly distributed to each guide vane inlet through the equal-sized connection surface, laying the foundation for precise guide vane guidance and sufficient water circulation. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the water pump turbine according to an embodiment of the present invention; Figure 2 This is a partial cross-sectional view of the flow guide shell according to an embodiment of the present invention; Figure 3 This is a partial cross-sectional view of the volute casing according to an embodiment of the present invention; Figure 4 This is a partial cross-sectional view of the water pump turbine according to an embodiment of the present invention; Figure 5 This is a three-dimensional structural diagram of the double-suction impeller and blades according to an embodiment of the present invention; Figure 6 This is a three-dimensional structural diagram of the double suction impeller and guide vanes according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the performance curves of the water pump and turbine operating in both directions according to an embodiment of the present invention. Detailed Implementation

[0020] The following detailed description illustrates the specific implementation method: The reference numerals in the accompanying drawings include: volute 1, guide shell 2, guide cavity 3, recess 4, mounting groove 5, rotating shaft 6, double suction impeller 7, blade 8, guide vane 9.

[0021] Example The basic implementation examples are as follows: Figures 1-7 As shown, Figure 1 The reversible pump-turbine shown includes a casing, a double-suction impeller 7, and guide vanes 9. The casing includes a volute 1 and a guide shell 2. The guide shell 2 is Y-shaped and wraps around the left and right sides of the volute 1, as shown. Figure 2 The guide shell 2 shown has symmetrically arranged semi-spiral guide cavities 3 inside, such as... Figure 3The volute 1 shown has a spiral cavity 4 inside, and the spiral outline is set as an Archimedean spiral. A mounting groove 5 communicating with the cavity 4 is located at the center of the volute 1, and both flow guide cavities 3 are connected to the mounting groove 5. A through mounting hole is provided in the flow guide shell 2, and the axis of the mounting hole coincides with the rotation axis 6 of the cavity 4 and the flow guide cavity 3. Figure 4 A rotating shaft 8 is rotatably mounted inside the mounting hole shown, and a double suction impeller 7 is fixedly mounted on the outer wall of the rotating shaft 8, as shown. Figure 5 The double-suction impeller 7 shown has several blades 8 fixedly and alternately installed on its two outer walls. These blades 8 are inclined and fixedly installed on the outer walls of the double-suction impeller 7, and the inclination angle of the blades 8 is set to θ1, where θ1 = 360° / (2π). Z1), where Z1 is the number of blades 8 on one side of the double-suction impeller 7, such as Figure 4 and Figure 6 The guide vane 9 shown is fixedly installed on the inner wall of the mounting groove 5, and the double suction impeller 7 is located inside the double suction impeller 7. The number of guide vanes 9 is set to Z2, and Z2=X2. Z1, where Z1 and Z2 are coprime numbers and cannot have a common divisor; X2 ranges from 1.2 to 1.6; the placement angle of guide vane 9 is set to 10-15°; the wrap angle of guide vane 9 is set to θ3, and θ3 = X3. θ2, where θ2 is the wrap angle of the outer wall blade 8 of the double suction impeller 7; X3 ranges from 0.25 to 0.5; the inlet diameter and inlet width of the cavity 4 are equal to the outlet diameter and outlet width of the guide vane 9, respectively, and the inlet diameter of the guide vane 9 is greater than the outlet diameter of the double suction impeller 7; the radial clearance between the blade 8 and the guide vane 9 is set to H, and H = X1. D1, where D1 is the outlet diameter of the double suction impeller 7, and X1 ranges from 0.03 to 0.06.

[0022] like Figure 7 The performance curves of the pump and turbine shown can be intuitively seen in the following ways: Pump mode: The green efficiency curve maintains high efficiency within the flow range of 500-1700, effectively reducing hydraulic losses and ensuring efficient pressurization and delivery of water under pump mode; Turbine mode: The purple efficiency curve highly overlaps with the high efficiency range of the pump mode efficiency curve, and the efficiency is stable at over 55% in the flow range of 1100-1700, avoiding the problem of high efficiency in one mode and efficiency decline in another.

[0023] The specific implementation process is as follows: The flow guide shell 2 is symmetrically wrapped around both sides of the volute 1, and spiral flow guide cavities 3 are symmetrically opened inside. Both flow guide cavities 3 are connected to the mounting groove 5. Together with the spiral cavity 4 inside the volute 1, they form a bidirectional smooth flow channel system. In pump operation, the double-helix guide cavity 3 can uniformly and smoothly introduce water flow into the double-suction impeller 7, avoiding flow field turbulence and swirl loss caused by unilateral water intake. In turbine operation, the guide cavity 3 can smoothly discharge water flow as a tailrace chamber, eliminating backflow eddies. The cavity 4 can realize stable water flow collection and transportation, greatly improving the flow channel efficiency. The blades 8 on both sides of the outer wall of the double-suction impeller 7 are staggered, which can effectively offset the impact force of water flow on the blades 8 during operation, reduce blade vibration and water flow pulsation, and improve the stability of unit operation. At the same time, in pump operation, the guide vane 9 can rectify the water flow at the outlet of the double-suction impeller 7, optimize the flow field distribution, and avoid water flow impact loss. In turbine operation, it can guide the water flow to form a reasonable pre-swirl, providing sufficient circulation for the double-suction impeller 7 to perform efficient work, and taking into account the energy conversion efficiency in both directions.

[0024] The above descriptions are merely embodiments of the present invention, and common knowledge such as specific technical solutions and / or characteristics are not described in detail here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the technical solutions of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the implementation of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A reversible pump-turbine, characterized by: The application relates to a double-suction impeller and guide vane, which comprises a shell, a double-suction impeller and a guide vane, wherein the shell comprises a volute and a guide shell, the volute is provided with a spiral cavity, the center of the volute is provided with an installation groove which is communicated with the cavity, the guide shell is Y-shaped and wrapped on the left and right sides of the volute, the guide shell is symmetrically provided with spiral guide cavities, the two guide cavities are communicated with the installation groove, the guide shell is provided with an installation hole, the axis of the installation hole coincides with the rotation axes of the cavities and the guide cavities, a rotating shaft is arranged in the installation hole, the double-suction impeller is arranged on the outer wall of the rotating shaft, a plurality of blades are staggered arranged on the outer walls of the two sides of the double-suction impeller, the guide vane is arranged in the installation groove, and the double-suction impeller is located in the guide vane.

2. A reversible pump turbine according to claim 1, characterized in that: The spiral contour line is an Archimedes spiral, and the guide cavity is a half spiral.

3. A reversible pump turbine according to claim 2, characterized in that: A plurality of blades are obliquely arranged on the outer wall of the double-suction impeller, and an inclination angle of the blades is θ1, and θ1=360° / (2 Z1), wherein Z1 is the number of blades on one side of the double-suction impeller.

4. A reversible pump-turbine according to claim 3, characterized in that: The number of vanes is set as Z2, and Z2=X2 Z1, wherein Z1 and Z2 are prime numbers and cannot have common factors, and X2 is in the range of 1.2-1.

6.

5. A reversible pump turbine according to claim 4, characterized in that: The setting angle of the guide vane is 10-15 DEG.

6. A reversible pump turbine according to claim 5, characterized in that: The wrap angle of the guide vanes is set to θ3, and θ3=X3 θ2, wherein θ2 is the wrap angle of the outer wall vanes of the double-suction impeller, and X3 is in the range of 0.25-0.

5.

7. A reversible pump turbine according to claim 6, characterized in that: The radial clearance between the blade and the guide vane is set as H, and H=X1 D1, wherein D1 is the double suction impeller outlet diameter, and X1 is in the range of 0.03-0.

06.

8. A reversible pump turbine according to claim 7, characterized in that: The inlet diameter and the inlet width of the cavity are equal to the outlet diameter and the outlet width of the guide vane respectively.

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