Corrosion reduction device of water turbine blade

Abstract

The utility model belongs to the technical field of hydraulic mechanical equipment, and particularly relates to a water turbine blade corrosion reduction device which comprises a volute and an air supply device, the air supply device comprises a mixing barrel, an annular filter plate is arranged in an inner cavity of the mixing barrel, a sand setting barrel is arranged on the outer wall of the bottom side of the volute, and a sand setting pipe is arranged at the bottom end of the sand setting barrel. The sand setting pipe sequentially penetrates through the mixing barrel and the filter plate to reach the mixing cavity; a first medium pipe communicated with the purification cavity is arranged at the upper end of the mixing barrel, a second medium pipe communicated with the mixing cavity is arranged at the lower end of the mixing barrel, and an air supplementing pipe communicated with the purification cavity is arranged in the middle of the mixing barrel; the first medium pipe penetrates through the runner chamber and is located on the upper sides of the blades, and the second medium pipe penetrates through the runner chamber and is located on the lower sides of the blades. Sand corrosion is directly reduced through sand discharging, meanwhile, sand discharging mixed liquid is filtered, a filtered clean water source is mixed with air, it is ensured that the air and water are evenly mixed and then sprayed into a runner chamber, and the better corrosion reduction and vibration reduction effects are achieved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of hydraulic machinery equipment, especially relates to an erosion reduction device for water turbine blade. BACKGROUND

[0002] When the water turbine operates at 40%-70% rated output, due to water flow disturbance, there is pressure pulsation in different degrees, and vortex band appears in the draft tube, and the strong disturbance of the vortex band or the coincidence of its frequency with the inherent frequency of the unit causes resonance, which causes unit vibration or load swing; the vortex band also destroys the flow surface of the water turbine, causing cavitation, sand erosion or cracks of the flow components.

[0003] Therefore, air needs to be supplemented when the water turbine unit appears unstable working condition to destroy the vortex band, thereby absorbing shock and reducing the intensity of the vortex to improve the operating condition of the unit.

[0004] At present, the most common air supplement method of the water turbine is draft tube air supplement and main shaft center hole air supplement, and the draft tube air supplement is usually used for small and medium-sized units, and the main shaft center hole air supplement is usually used for medium and large-sized units. The main shaft center air supplement of the water turbine is to supplement air to the runner outlet where the runner water discharge cone is located through the main shaft center hole. However, the draft tube air supplement and the main shaft air supplement can usually only be used to solve the problem at the axis of the runner tail, however, the blade tail of the water turbine (especially the reaction water turbine) also produces severe disturbance and cavitation phenomenon when it operates at high speed, which not only causes vibration and damage of the blade tail, but also accumulates to the tail of the runner. Therefore, the blade tail of the water turbine also needs to be damped and eroded.

[0005] The main effect of air supplement is to reduce cavitation, but the effect on sand erosion is not obvious, even ineffective. Air supplement uses the "softness" of air to buffer the "hardness" impact when the air bubble collapses. Sand erosion is a purely physical cutting process. The hard sand particles carried in the high-speed water flow directly impact and cut the blade surface like sandpaper. Therefore, an erosion reduction device for water turbine blade is needed to efficiently reduce cavitation and sand erosion. UTILITY MODEL CONTENTS

[0006] In view of the technical problems in the background art, the utility model provides an erosion reduction device for water turbine blade.

[0007] To achieve the above-mentioned purpose, the technical scheme provided by the utility model is:

[0008] An erosion reduction device for water turbine blade, comprising a spiral case, a water guide pipe in communication with the side wall of the spiral case, a runner chamber in communication with the bottom of the spiral case, guide vanes arranged in the spiral case, a runner arranged in the runner chamber, and a paddle arranged on the outer wall of the runner, further comprising an air supplement device arranged on the periphery of the runner chamber.

[0009] The air supplementing device comprises a ring-shaped mixing cylinder, an inner cavity of the mixing cylinder is provided with a ring-shaped filter plate for separating the inner cavity of the mixing cylinder into a purification cavity and a mixing cavity, an outer wall of a bottom side of the volute is provided with at least one sand setting cylinder, a bottom end of the sand setting cylinder is provided with a sand setting pipe, the sand setting pipe passes through the mixing cylinder and the filter plate in sequence to reach the mixing cavity, an upper end of the mixing cylinder is provided with a first medium pipe in communication with the purification cavity, a lower end of the mixing cylinder is provided with a second medium pipe in communication with the mixing cavity, and a middle part of the mixing cylinder is provided with an air supplementing pipe in communication with the purification cavity.

[0010] The first medium pipe passes through the runner chamber and is located at an upper side of the paddle, and the second medium pipe passes through the runner chamber and is located at a lower side of the paddle.

[0011] Optionally, the volute comprises a first volute segment, a second volute segment, a third volute segment, a fourth volute segment, a fifth volute segment and a sixth volute segment connected in sequence, one end of the first volute segment is connected with the water guide pipe, and a tail end of the sixth volute segment is connected with the first volute segment to form a ring-shaped volute shape; the bottom end of each of the second volute segment, the third volute segment, the fourth volute segment, the fifth volute segment and the sixth volute segment is provided with one sand setting cylinder.

[0012] Optionally, the volute comprises a first volute segment, a second volute segment, a third volute segment, a fourth volute segment, a fifth volute segment and a sixth volute segment connected in sequence, one end of the first volute segment is connected with the water guide pipe, and a tail end of the sixth volute segment is connected with the first volute segment to form a ring-shaped volute shape; at least one of the fifth volute segment and the sixth volute segment is provided with a sand guide pipe at an outer wall thereof.

[0013] Optionally, the sand setting pipe is provided with a first valve.

[0014] Optionally, the first medium pipe is provided with a second valve.

[0015] Optionally, the second medium pipe is provided with a third valve.

[0016] Optionally, the bottom end of the mixing cylinder is provided in a conical shape, the air supplementing pipe is arranged on the outer wall of the mixing cylinder, the air supplementing pipe extends into the purification cavity and is opposite to the first medium pipe.

[0017] Optionally, the first medium pipe, the second medium pipe and the air supplementing pipe are distributed in a plurality of portions along the circumference of the mixing cylinder.

[0018] Optionally, a relief groove is formed in one side of the mixing cylinder, and one side of the water guide pipe is arranged in the relief groove.

[0019] Optionally, the runner chamber comprises a cylindrical section and a conical section, the runner is located in the cylindrical section, the first medium pipe is inclined to extend into the interior of the cylindrical section, and the second medium pipe is inclined to extend into the interior of the conical section; the height of the top of the first medium pipe is higher than the height of the top of the mixing cylinder body, and the height of the top of the first medium pipe is lower than the height of the bottom of the sand setting cylinder.

[0020] The utility model has the advantages and beneficial effects that:

[0021] In the utility model, the sand setting cylinder is arranged at the source of the spiral case to discharge sand, and the discharged cement sand mixed liquid is filtered through the mixing cylinder body, part of the filtered sand can be discharged to the bottom side of the runner through the second medium pipe on the bottom side, avoiding the runner and avoiding direct impact on the runner to cause sand erosion, and the water with low sand content after filtration reaches the purification cavity to mix with air and is sprayed into the runner chamber through the first medium pipe. The sand erosion is directly reduced by discharging sand, the sand mixed liquid is filtered, the clean water source after filtration is mixed with air, the air and the water body are uniformly mixed and sprayed into the runner chamber, the effect of better erosion reduction and vibration reduction is achieved, the sand mixed liquid does not contain sand, and the runner and the paddle are not abraded and eroded. Compared with directly injecting air into the runner chamber, a large number of small bubbles are formed by early mixing, the bubbles are fine and uniformly distributed, and the impact absorbing capacity is stronger. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a structure view of the erosion reduction device for the runner blade of the water turbine;

[0023] Figure 2 It is a second structure view of the erosion reduction device for the runner blade of the water turbine;

[0024] Figure 3 It is a front view of the erosion reduction device for the runner blade of the water turbine;

[0025] Figure 4 It is Figure 3 It is a sectional view along the A-A direction;

[0026] Figure 5 It is Figure 3 It is a top view;

[0027] Figure 6 It is Figure 3 It is a bottom view;

[0028] Figure 7 It is a structure view of the sand guide pipe arranged on the spiral case side wall of the utility model;

[0029] Figure 8 It is a structure view of the filter plate of the utility model;

[0030] Figure 9 It isFigure 8 Close-up view at a.

[0031] Reference: 1-volute, 11-first volute section, 12-second volute section, 13-third volute section, 14-fourth volute section, 15-fifth volute section, 16-sixth volute section, 17-sand guide pipe, 2-water guide pipe, 21-flange, 3-mixing cylinder, 31-avoidance groove, 32-filter plate, 321-filter hole, 322-mounting hole, 33-baffle, 4-runner chamber, 5-sand setting cylinder, 51-sand setting pipe, 52-first valve, 6-air supplement pipe, 61-arc-shaped nozzle, 62-air injection hole, 7-second medium pipe, 71-third valve, 8-first medium pipe, 81-second valve, 9-main shaft, 91-runner, 92-paddle, 93-guide vane. DETAILED DESCRIPTION

[0032] To make the objects, technical solutions, and advantages of the embodiments of the present application clearer, the following will be a clear and complete description of the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application.

[0033] Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art without creative labor based on the embodiments in the present application are within the scope of protection of the present application.

[0034] EMBODIMENT

[0035] As Figures 1-8 shown, an erosion reduction device for water turbine blades includes a volute 1, a water guide pipe 2 in communication with the side wall of the volute 1, a runner chamber 4 in communication with the bottom of the volute 1, a guide vane 93 arranged in the volute 1, a runner 91 arranged in the runner chamber 4, and a paddle 92 arranged on the outer wall of the runner 91. The upper end of the runner 91 is connected with a main shaft 9, and the main shaft 9 is rotatably arranged in the volute 1 through a bearing. The guide vanes 93 are evenly distributed along the annular inner cavity of the volute 1. Water flows into the volute 1 from the gaps between adjacent guide vanes 93 after flowing into the volute 1 from the water guide pipe 2, and then flows through the runner 91 and the paddle 92 on the bottom side, and finally is discharged from the tail pipe on the bottom side of the runner chamber 4.

[0036] As Figures 1-7 shown, the erosion reduction device for water turbine blades further includes an air supplement device arranged on the periphery of the runner chamber 4, for supplying compressed air into the runner chamber 4 to reduce cavitation.

[0037] As Figures 1-9As shown, the air supplementing device comprises an annular mixing cylinder 3, which is sleeved outside the runner chamber 4, and the inner cavity of the mixing cylinder 3 is provided with an annular filter plate 32 for separating the inner cavity of the mixing cylinder 3 into a purification cavity and a mixing cavity, and a plurality of filter holes 321 are arranged on the filter plate 32. The purpose of the filter plate 32 is to filter the mud and sand in the water and provide clean water source for air supplementing. The filter plate 32 is close to the upper side of the mixing cylinder 3, so that the volume of the purification cavity is far less than that of the mixing cavity. The size and number of the filter holes of the filter plate 32 are set according to the actual situation, so that the water and air entering the purification cavity reach the designed ratio, the speed is suddenly changed by artificial manufacturing, the high-speed air jet group is formed by using small space to generate strong turbulence, so that the air is broken into extremely small bubbles and fully mixed with water. By designing the filter holes and adjusting the air inlet size, the gas concentration of the bubble mixture sprayed into the runner chamber can be accurately controlled, so that the best erosion and vibration reduction effect is achieved.

[0038] As shown in Figures 1-8 The bottom side outer wall of the volute 1 is provided with at least one tapered sand setting cylinder 5, the sand setting cylinder 5 is communicated with the volute 1, the bottom end of the sand setting cylinder 5 is provided with a sand setting pipe 51, the sand setting pipe 51 passes through the mixing cylinder 3 and the filter plate 32 in sequence and reaches the mixing cavity. The filter plate 32 is provided with a mounting hole 322, and the sand setting pipe 51 passes through the mounting hole 322. The upper end of the mixing cylinder 3 is provided with a first medium pipe 8 communicated with the purification cavity, the lower end of the mixing cylinder 3 is provided with a second medium pipe 7 communicated with the mixing cavity, and the middle part of the mixing cylinder 3 is provided with an air supplementing pipe 6 communicated with the purification cavity, the air supplementing pipe 6 is connected with an air supply device outside, and is used for passing in compressed air.

[0039] As shown in Figures 1-7 The first medium pipe 8 passes through the runner chamber 4 and is located at the upper side of the paddle 92, and the second medium pipe 7 passes through the runner chamber 4 and is located at the lower side of the paddle 92. The first medium pipe 8 is used for air supplementing, and the second medium pipe 7 is used for sand discharging.

[0040] The utility model discloses a mixing cavity is located in the lower part, and the purification cavity is located in the upper part, forms the'reverse filtration up flow'of unique. When working, sand-containing water flows through sand setting pipe 51 and enters the bottom mixing cavity and carries out gravity sedimentation, and the upper clear liquid is driven upward and passes through filter plate 32. Due to the throttling effect of filter plate 32, the water flow forms a high-speed vertical upward micro jet group in the moment of entering the purification cavity. At the same time, compressed air is sprayed into the purification cavity through the arc-shaped nozzle 61, forming a high-speed air jet group perpendicular to the vertical water jet. The two jets have strong'cross-flow impact and momentum exchange'in the small purification cavity space, utilize the high turbulent kinetic energy dissipation rate in the limited space, tear the air into micron-sized bubbles, and fully emulsify with water to form a homogeneous gas-liquid mixed flow. Finally, the mixed flow is sprayed into the upper side of the paddle 92 in the runner chamber 4 through the first medium pipe 8. This structure cleverly utilizes the orthogonal shearing effect of the vertical upward flow and the transverse compressed air flow, realizes the efficient micro-mixing of gas and liquid, and significantly improves the air supplementing and erosion reduction effect.

[0041] The utility model discloses a waste water source of spiral case sand discharge is converted into the " clean water source " required by air supplementing on the spot, realizes the circulation linkage of sand discharge and air supplementing. The sand setting cylinder 5 is arranged at the source of spiral case 1 to discharge sand, and the discharged cement sand mixed liquid is filtered through the mixing cylinder body 3, and part of the filtered sand can be discharged to the bottom side of the runner 91 through the second medium pipe 7 on the bottom side, avoiding the runner 91, to avoid sand erosion to the runner 91, and the low sand containing water after filtering mixes with air in the purification cavity and is sprayed into the runner chamber 4 from the first medium pipe 8. Directly reduce sand erosion through sand discharge, filter the sand discharge mixed liquid, mix the filtered clean water source with air, ensure that air and water are uniformly mixed and sprayed into the runner chamber 4, have better erosion reduction and vibration reduction effect, and the mixed liquid does not contain sand, and will not cause abrasion and sand erosion to the runner 91 and paddle 92.

[0042] As shown in Figures 1-6 The spiral case 1 includes the first spiral case section 11, the second spiral case section 12, the third spiral case section 13, the fourth spiral case section 14, the fifth spiral case section 15 and the sixth spiral case section 16 connected in sequence, and the spiral case sections are detachably connected through flanges. One end of the first spiral case section 11 is connected with the flange plate 21 of the water guide pipe 2, and the tail end of the sixth spiral case section 16 is transitionally connected with the first spiral case section 11 to form a ring-shaped spiral case 1. The bottom ends of the second spiral case section 12, the third spiral case section 13, the fourth spiral case section 14, the fifth spiral case section 15 and the sixth spiral case section 16 are respectively provided with a sand setting cylinder 5. Since the first spiral case section 11 is directly connected with the water guide pipe 2, the diameters of the two are relatively large, and they are located at the water source inlet side, so the sand setting cylinder 5 can not be arranged, but arranged at the rear other spiral case sections, thereby realizing efficient sand discharge operation.

[0043] As shown in Figure 7 The spiral case 1 includes the first spiral case section 11, the second spiral case section 12, the third spiral case section 13, the fourth spiral case section 14, the fifth spiral case section 15 and the sixth spiral case section 16 connected in sequence, and one end of the first spiral case section 11 is connected with the water guide pipe 2, and the tail end of the sixth spiral case section 16 is connected with the first spiral case section 11 to form a ring-shaped spiral case 1. At least one of the fifth spiral case section 15 and the sixth spiral case section 16 is provided with a sand guide pipe 17 on the outer side wall thereof. In addition to the sand setting cylinder 5 arranged at the bottom side of the spiral case 1, the sand guide pipe 17 can also be arranged at the tail end of the spiral case 1, i.e. the outer side walls of the subsequent two spiral case sections (the fifth spiral case section 15 and the sixth spiral case section 16), along the natural impact direction of the water flow, to naturally discharge sand in the water flow impact direction and into the mixing cylinder body 3 at the bottom side.

[0044] As shown in Figures 1-7 The first valve 52 is arranged on the sand setting pipe 51 and can control the sand setting cylinder 5 to open for water and sand discharge and control the discharge flow.

[0045] As Figures 1-7 shown, the first medium pipe 8 is provided with a second valve 81, which can control the opening and closing of the first medium pipe 8, carry out air supplement, and discharge the gas-liquid mixed liquid in the purification cavity into the runner chamber 4.

[0046] As Figures 1-7 shown, the second medium pipe 7 is provided with a third valve 71, which can control the opening of the mixing cylinder 3 to discharge water and sand.

[0047] In the utility model, the first valve 52 preferably uses a wear-resistant rising stem gate valve or an eccentric half-ball valve. The valve is located at the sand pipe at the bottom of the volute, the medium is high-concentration sand-containing water flow, and it is the position with the highest wear risk among the three valves. When automatic control is adopted, an electric eccentric half-ball valve can be selected.

[0048] In the utility model, the second valve 81 preferably uses an electric ball valve or an electromagnetic valve. The valve controls the gas-liquid mixed flow in the purification cavity, the medium is water containing micro-bubbles, and it needs to cooperate with compressed air to form jetting. The opening and closing frequency is relatively high (changes with the working condition of the group).

[0049] In the utility model, the third valve 71 preferably uses a wear-resistant double-jaw butterfly valve or a knife-type gate valve. The valve is located at the bottom of the mixing cylinder, and it discharges the deposited thick slurry-shaped sand, has a low opening frequency, but requires unobstructed flow passage when opened.

[0050] As Figures 1-7 shown, the bottom end of the mixing cylinder 3 is provided in a conical shape to achieve better sand settling. The air supplement pipe 6 is arranged on the outer wall of the mixing cylinder 3, and the air supplement pipe 6 extends into the purification cavity and is opposite to the first medium pipe 8.

[0051] As Figure 8 and Figure 9 shown, further, the air supplement pipe 6 is connected with an arc-shaped jet pipe 61, the arc-shaped jet pipe 61 is located in the purification cavity, a plurality of jet holes 62 are uniformly distributed on the arc-shaped jet pipe 61, the jet holes 62 penetrate through the two end side walls of the arc-shaped jet pipe 61, and can jet gas from both sides. The arc-shaped jet pipes 61 are symmetrically arranged on both sides of the sand pipe 51 to achieve uniform mixing.

[0052] When the first valve 52 is opened, the sand is mixed with the water flow into the mixing chamber at the bottom of the mixing cylinder 3, at this time, the third valve 71 is closed, and the second valve 81 is opened, the water flow flows upwards through the filter plate 32, the sand is deposited at the bottom of the mixing chamber, and the purified water is mixed with the air introduced from the air supplement pipe 6 into the purification chamber and then sprayed from the first medium pipe 8, so that the high-speed flowing water source is branched from the volute 1, and the sand is drained to the mixing chamber during the sand draining of the sand cylinder 5, realizing efficient sand draining, and the sand mixed liquid is filtered and then supplemented into the runner chamber 4 with air, without the help of external water source, the sand draining and air supplementing operations can be completed, and the cavitation and sand erosion can be reduced. When draining the sand, the first valve 52 is closed, the second valve 81 is closed, and the third valve 71 is opened, the sand is drained by gravity, and compressed air can be introduced from the air supplement pipe 6 to assist the sand draining, and the filter plate 32 is cleaned efficiently.

[0053] As shown in Figures 1-7 , the first medium pipe 8, the second medium pipe 7 and the air supplement pipe 6 are uniformly distributed along the circumference of the mixing cylinder 3. As shown in Figure 8 and Figure 9 , of course, in order to better realize uniform mixing, a vertical partition plate 33 can be arranged in the purification chamber, the bottom side of the partition plate 33 is fixed with the filter plate 32, and the upper side is fixed with the top wall of the mixing cylinder 3, the purification chamber is divided into multiple independent chambers in the circumference, each chamber corresponds to an air supplement pipe 6, so as to realize sufficient mixing of gas and water flow.

[0054] As shown in Figures 1-7 , a avoiding groove 31 is formed on one side of the mixing cylinder 3, and one side of the water guide pipe 2 is arranged in the avoiding groove 31, realizing avoiding installation.

[0055] As shown in Figures 1-7 , the runner chamber 4 includes a cylindrical section and a conical section, the runner 91 is located in the cylindrical section, the first medium pipe 8 is inclined upward and extends into the inside of the cylindrical section, and the second medium pipe 7 is inclined downward and extends into the inside of the conical section. The height of the top of the first medium pipe 8 is higher than the height of the top of the mixing cylinder 3, and the height of the top of the first medium pipe 8 is lower than the height of the bottom of the sand cylinder 5. Since the outer diameter of the volute 1 is gradually changed, in order to ensure the installation of the mixing cylinder 3, the mixing cylinder 3 needs to be arranged at the bottom side of the volute 1, therefore, the first medium pipe 8 needs to be inclined upward and extend into the inside of the cylindrical section, so as to be located at the upper side of the paddle 92 for air supplementing. At the same time, the height of the top of the first medium pipe 8 is lower than the height of the bottom of the sand cylinder 5, so as to ensure a certain height difference, the water source can flow into the mixing chamber naturally, and is sprayed from the first medium pipe 8 with high-pressure air.

[0056] The above merely is preferred embodiment of the present utility model, and is not used for limiting the present utility model, for the person skilled in the art, the present utility model can have various changes and changes. Any modification, equivalent replacement, improvement etc. that is made within the spirit and principle of the present utility model should be contained in the protection scope of the present utility model.

Claims

1. An erosion reduction device for a water turbine blade, comprising a spiral case, a draft tube in communication with a side wall of the spiral case, a runner chamber in communication with a bottom of the spiral case, a guide vane provided in the spiral case, a runner provided in the runner chamber, and a paddle provided on an outer wall of the runner, characterized in that: The air supplement device is arranged on the periphery of the runner chamber; ​ The air supplement device comprises an annular mixing cylinder, an inner cavity of the mixing cylinder is provided with an annular filter plate, the inner cavity of the mixing cylinder is divided into a purification cavity and a mixing cavity, the bottom side outer wall of the volute is provided with at least one sand setting cylinder, the bottom end of the sand setting cylinder is provided with a sand setting pipe, the sand setting pipe passes through the mixing cylinder and the filter plate in sequence and reaches the mixing cavity, the upper end of the mixing cylinder is provided with a first medium pipe in communication with the purification cavity, the lower end of the mixing cylinder is provided with a second medium pipe in communication with the mixing cavity, and the middle part of the mixing cylinder is provided with an air supplement pipe in communication with the purification cavity. The first medium pipe passes through the runner chamber and is located on the upper side of the paddle, and the second medium pipe passes through the runner chamber and is located on the lower side of the paddle.

2. An apparatus for erosion reduction of a water turbine blade as defined in claim 1, wherein: The volute comprises a first volute section, a second volute section, a third volute section, a fourth volute section, a fifth volute section and a sixth volute section which are sequentially connected end to end, one end of the first volute section is connected with the water guide pipe, and the tail end of the sixth volute section is connected with the first volute section to form an annular volute shape; the bottom ends of the second volute section, the third volute section, the fourth volute section, the fifth volute section and the sixth volute section are respectively provided with one sand setting cylinder.

3. The apparatus for erosion reduction of a water turbine blade of claim 1, wherein: The volute comprises a first volute section, a second volute section, a third volute section, a fourth volute section, a fifth volute section and a sixth volute section which are sequentially connected end to end, one end of the first volute section is connected with the water guide pipe, and the tail end of the sixth volute section is connected with the first volute section to form an annular volute shape; at least one of the fifth volute section and the sixth volute section is provided with a sand guide pipe on the outer side wall thereof.

4. The apparatus for erosion reduction of water turbine blades of claim 2, wherein: The sand setting pipe is provided with a first valve.

5. The apparatus for erosion reduction of water turbine blades of claim 2, wherein: The first medium pipe is provided with a second valve.

6. The apparatus for erosion reduction of water turbine blades of claim 2, wherein: The second medium pipe is provided with a third valve.

7. The apparatus for erosion reduction of water turbine blades of claim 2, wherein: The bottom end of the mixing cylinder is provided in a conical shape, the air supplement pipe is arranged on the outer wall of the mixing cylinder, the air supplement pipe extends into the purification cavity and is opposite to the first medium pipe; the tail end of the air supplement pipe is connected with an arc-shaped nozzle, the arc-shaped nozzle is located in the purification cavity, and the arc-shaped nozzles are symmetrically arranged on the two sides of the sand setting pipe.

8. The apparatus of claim 7, wherein: The first medium pipe, the second medium pipe and the air supplement pipe are uniformly distributed along the circumference of the mixing cylinder.

9. The apparatus for erosion reduction of water turbine blades of claim 1, wherein: One side of the mixing cylinder is provided with a avoiding groove, and one side of the water guide pipe is arranged in the avoiding groove.

10. The apparatus for erosion reduction of water turbine blades of claim 1, wherein: The runner chamber comprises a cylindrical section and a conical section, the runner is located in the cylindrical section, the first medium pipe extends into the interior of the cylindrical section in an inclined manner upwards, and the second medium pipe extends into the interior of the conical section in an inclined manner downwards; the height of the top of the first medium pipe is higher than the height of the top of the mixing cylinder, and the height of the top of the first medium pipe is lower than the height of the bottom of the sand setting cylinder.

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