A volute tongue and a water turbine using the same

Abstract

The present invention discloses a volute tongue and a water turbine using the same. The volute tongue is arranged at the intersection of the end and the start of the volute, and has an opening for shortening the communication path between the end and the start of the volute. The volute of the water turbine is provided with the volute tongue. In the present invention, by opening a hole in the volute tongue, the communication path between the end and the start of the volute can be shortened, thereby effectively reducing or avoiding high-frequency pressure pulsation in the bladeless area between the movable guide vane and the runner.

Description

Technical Field

[0001] The invention relates to the technical field of water turbines, in particular to a volute and a water turbine using the same. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] High-drop water turbines include water turbines, pumps and pump-turbines. Under certain combinations of runner blades and movable guide vanes, there are high-frequency pressure pulsations in the bladeless area between the movable guide vanes and the runner that are related to the number of runner blades and the rotation frequency. Typically, there are high-frequency water pressure pulsations that are twice the blade passing frequency, which in turn causes high-frequency vibration of the top cover and high-frequency noise of the machine. The main reasons are the dynamic-static interference between the runner blades and the movable guide vanes and the phase resonance caused by the dynamic-static interference.

[0004] In some engineering practices known to the inventor, the following methods are used:

[0005] 1. Forced Qi replenishment in leafless areas

[0006] By forcibly replenishing air in the bladeless area, the flow field characteristics of the bladeless area can be destroyed, which has the effect of reducing the intensity of dynamic and static interference. At the same time, increasing the compressibility in the flow channel can also change the propagation speed of the pressure wave, thereby affecting the characteristics of possible phase resonance. This measure has been tested in a large number of engineering practices. Many power plants have adopted air replenishment measures to solve the noise and vibration problems caused by the vortex belt in the tailwater pipe. Although the implementation location of air replenishment in the bladeless area is different, the principle is the same.

[0007] However, this technical solution has the following disadvantages:

[0008] (1) Under the working conditions where the vibration and noise caused by the pump turbine of a pumped storage power station is high, the pressure in the bladeless area is very high. When the air supply pressure is lower than the pressure in the bladeless area, air supply may not be achieved. Therefore, the air supply pressure must be greater than the pressure in the bladeless area.

[0009] (2) Conventional gas replenishment measures in power plants are adopted under specific working conditions or specific loads. The gas replenishment volume and pressure are small and the gas replenishment time is short. However, noise and vibration of some power plants occur when they are close to full load. The bladeless area of ​​the top cover is in the high-pressure area, which requires continuous, long-term, high-pressure and large-flow gas replenishment. This places high demands on the safety of the equipment and requires a large site support, resulting in huge implementation costs.

[0010] (3) Due to the limitation of the top cover space, the opening diameter allowed by the top cover is relatively small. When high-pressure and high-flow gas passes through the branch pipe, it is easy to cause the gas flow rate in the pipeline to be too high, which has the potential risk of increasing the vibration of the top cover and the noise of the waterwheel room.

[0011] (4) Since the air supply causes a large disturbance to the flow field at the turbine inlet, it will inevitably lead to a certain efficiency loss.

[0012] 2. Reshape the runner itself

[0013] The high pressure edge of the runner blade is modified to a shape that is concave and curved toward the downstream to increase the radial distance between the guide vane outlet and the high pressure edge of the runner blade, thereby reducing the influence of dynamic and static interference, see Chinese Patent ZL201280019539.

[0014] However, this technical solution has the following disadvantages:

[0015] (1) The implementation cost is high. For power plants that are already in operation, it is necessary to repair the installed equipment such as the runner and the top cover. The implementation cost is huge, and the power plant cannot afford the economic loss caused by the shutdown of the power plant due to the repair.

[0016] (2) For some power stations, vibration reduction methods have been considered at the beginning of the design, and conventional wheel modification can no longer change the generation of vibration noise. Summary of the invention

[0017] In view of the above-mentioned problems, the present invention provides a volute tongue and a water turbine using the same. By opening a hole in the volute tongue, the connection path between the end and the beginning of the volute can be shortened, thereby effectively reducing or avoiding high-frequency pressure pulsation in the bladeless area between the movable guide vane and the impeller.

[0018] The invention discloses a volute tongue, which is arranged at the intersection of a volute end and a start end and has an opening for shortening the communication path between the volute end and the start end.

[0019] Furthermore, the inner side of the volute has openings connected to seat rings at upper and lower edges, a plurality of groups of fixed guide vanes are arranged between the seat rings, and the volute tongue is arranged at the intersection of the end and the starting end of the volute and extends to the seat rings.

[0020] Furthermore, the opening is located near the outer edge of the seat ring.

[0021] Furthermore, the volute tongue is divided into two parts by the opening, and the part located on the seat ring has the same or similar shape as the fixed guide vane.

[0022] Furthermore, the height of the opening is equal to or nearly equal to the distance between the two seat rings.

[0023] Furthermore, the opening is in a rectangular, circular or elliptical shape.

[0024] Based on any of the above-mentioned volute tongues, the present invention further discloses a water turbine, comprising a volute, fixed guide vanes, movable guide vanes and a runner, wherein the volute has any of the above-mentioned volute tongues.

[0025] Furthermore, the opening of the volute is used to supply water to the impeller.

[0026] In the present invention, by opening holes at appropriate positions on the volute tongue, there are at least the following two advantages:

[0027] 1. It can balance the pressure on both sides and reduce the intensity of dynamic and static interference;

[0028] 2. It can change the propagation path of the pressure wave in the volute to a certain extent, thereby affecting the phase resonance.

[0029] Since the holes opened on the volute tongue can produce at least the above two effects, the present invention can effectively reduce or avoid the high-frequency pressure pulsation related to the number of impeller blades and the rotation frequency generated in the bladeless area between the movable guide vane and the impeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0031] Figure 1 Schematic diagram of the position and shape of the opening on the volute tongue from a vertical section view of the starting end of the volute in some embodiments;

[0032] Figure 2 is a schematic diagram of the position and shape of the openings on the volute tongue when the volute is horizontally cut through in some embodiments;

[0033] Figure 3 It is a schematic diagram of the structure of the volute tongue before the opening from a vertical section perspective of the starting end of the volute;

[0034] Figure 4 It is a schematic diagram of the structure of the volute tongue before the opening in a horizontal section of the volute.

[0035] Description of reference numerals:

[0036] 1-volute, 2-volute tongue, 21-nose fixed guide vane, 3-fixed guide vane, 4-seat ring. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention.

[0038] In the description of the present invention, it is necessary to understand that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing 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 cannot be understood as a limitation on the present invention.

[0039] In the drawings of the present invention, it is necessary to understand that different technical features that are not mutually replaceable are shown in the same drawing only for the purpose of simplifying the description of the drawings and reducing the number of drawings, rather than indicating or implying that the embodiments described with reference to the drawings include all the technical features in the drawings. Therefore, it cannot be understood as a limitation of the present invention.

[0040] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" and the like 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 direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] like Figure 1-2 As shown, the present invention discloses a volute tongue 2, which is arranged at the intersection of the end and the starting end of the volute 1, and has an opening for shortening the communication path between the end and the starting end of the volute 1. The inner side of the volute 1 has openings connected to seat rings 4 at the upper and lower edges, and a plurality of groups of fixed guide vanes 3 are arranged between the seat rings 4. The volute tongue 2 is arranged at the intersection of the end and the starting end of the volute 1 and extends to the seat ring 4.

[0042] The structure of the snail tongue 2 before opening is as follows: Figure 3-4As shown, it can be seen that even if no hole is made on the volute tongue 2, the end and the starting end of the volute 1 are connected, but the connecting path needs to bypass the entire volute tongue 2. Therefore, in the present invention, by making a hole on the volute tongue 2, the connecting path between the end and the starting end of the volute 1 can be shortened and / or changed, and the connectivity of the flow field between the end and the starting end of the volute 1 can be improved. This has at least the following two effects: on the one hand, it can balance the pressure on both sides of the volute tongue 2, which plays a role in reducing the dynamic and static interference intensity; on the other hand, it can change the propagation path of the pressure wave in the volute 1 to a certain extent, thereby affecting the phase resonance. The above two effects generated by the hole on the volute tongue 2 can effectively reduce or avoid the high-frequency pressure pulsation related to the number of runner blades and the rotation frequency in the bladeless area between the movable guide vane and the runner.

[0043] Through actual modeling, the flow field and structural strength before and after the opening are studied to determine the appropriate position and size of the opening on the volute tongue 2. In some embodiments, the opening is located near the outer edge of the seat ring 4, and the volute tongue 2 is divided into two parts by the opening. The part located on the seat ring 4 is the same or similar in shape to the fixed guide vane 3, which can be called the nose fixed guide vane 21. In other embodiments, the shape of the opening is circular or elliptical or rectangular with chamfers, etc., and the height of the opening is equal to or nearly equal to the 4 spacing between the two seat rings. By comparing and analyzing the flow channel before and after the opening, the hydraulic performance of the opening scheme and the influence of the rigidity of the opening scheme are also analyzed, proving that the implementation of this scheme is feasible and has excellent implementation effects.

[0044] The present invention also provides a water turbine, comprising a volute 1, a fixed guide vane 3, a movable guide vane and a runner, wherein the volute 1 has any of the above-mentioned volute tongues 2. The fixed guide vane 3 is arranged along the inner circumference of the volute 1, and the movable guide vane is arranged along the inner circumference of the fixed guide vane 3 and is located at the outer circumference of the runner. The opening of the volute 1 is used to supply water to the runner.

[0045] At least one exemplary embodiment is now provided in conjunction with the accompanying drawings. The detailed description of the exemplary embodiments provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents the exemplary embodiments provided in the present invention.

[0046] Exemplary Embodiment 1

[0047] The above technical solution of drilling holes on the volute tongue 2 was actually implemented and the effect was verified on the unit. According to the actual maintenance plan of the power station, the unit to be implemented in the scheme was determined. The drilling required shutdown and drainage before construction, and there was no need to lift out the runner and other components when drilling holes. The operator and the drilling-related equipment entered through the extension of the seat ring 4, and the diameter of the entrance door was φ600mm. Combined with the actual situation on site, after comprehensive analysis and consideration, it was decided to adopt the "magnetic drilling and drilling + cutting and blowing + grinding" solution, and the drilling solution was implemented in less than two weeks.

[0048] After the hole was opened, the machine was restarted and tested, and the following conclusions were drawn: According to actual measurements in the power station, the main frequency of pressure pulsation in the bladeless area (128.6 Hz) was reduced to 80% of that before the hole was opened; the main frequency of top cover vibration (128.6 Hz) was reduced to 70% of that before the hole was opened, indicating that opening a hole on the snail tongue 2 has a significant effect on reducing the pressure pulsation in the bladeless area and the vibration of the top cover.

[0049] The present invention is not limited to the above-mentioned specific embodiments, but extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. A snail tongue, characterized in that: It is arranged at the intersection of the end and the starting end of the volute, and has an opening for shortening the communication path between the end and the starting end of the volute; The inner side of the volute has openings connected to seat rings at upper and lower edges, and a plurality of fixed guide vanes are arranged between the seat rings. The volute tongue is arranged at the intersection of the end and the starting end of the volute and extends to the seat ring; The opening is located near the outer edge of the seat ring; The volute tongue is divided into two parts by the opening, and the part located on the seat ring has the same or similar shape as the fixed guide vane; The height of the opening is equal to or nearly equal to the spacing between the two seat rings; The opening is in a rectangular, circular or elliptical shape.

2. A water turbine, characterized in that: The invention comprises a volute, fixed guide vanes, movable guide vanes and a runner, wherein the volute has a volute tongue as claimed in any one of claims 1.

3. The water turbine according to claim 2, characterized in that: The opening of the volute is used to supply water to the impeller.

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