Water pump open impeller capable of inhibiting gap cavitation and open impeller pump

Abstract

The invention discloses a water pump open-type impeller capable of inhibiting clearance cavitation and an open-type impeller pump, relates to the technical field of clearance cavitation inhibition of water pump impellers, and aims to solve the problem that a pump body vibrates due to the fact that blackspots and cracks appear on the surface of an existing water pump open-type impeller due to clearance cavitation, even the water pump open-type impeller falls off step by step in a spongy shape and generates noise. Comprising an impeller hub and blades, and the multiple blades are evenly arranged on the impeller hub in the circumferential direction. The side, directly facing the incoming flow of the water diversion pipe, of each blade is a water inlet edge, the side, corresponding to the downstream diffusion pipe, of each blade is a water outlet edge, the intersection point of each water inlet edge and the rim face is A, the intersection point of each water inlet edge and the hub face is B, and the impeller rim side wrap angle formed by the intersection point A and the vertical line and the longitudinal plane of the impeller hub axis is phi A, the impeller hub side wrap angle formed by the intersection point B and the vertical line and the longitudinal plane of the axis of the impeller hub is phi B, phi A is larger than phi B, and the difference value of phi A and phi B is 10-30 degrees.

Description

Technical Field

[0001] The invention relates to the technical field of water pump impeller clearance cavitation suppression, in particular to a water pump open impeller capable of suppressing clearance cavitation. Background Art

[0002] Axial flow pumps play a very important role in the national economy due to their large flow, reliable operation, economical investment and low cost. They are widely used in the fields of farmland irrigation, urban water supply and drainage, water diversion projects, etc. Axial flow pumps use open impellers to ensure axial flow in and out, and stably output the required flow within a wide range of head changes.

[0003] When the inlet pressure of the impeller pump is less than the saturated vapor pressure of the liquid at ambient temperature, a large amount of steam escapes from the liquid and mixes with the gas to form many small bubbles. When the gas reaches the high-pressure area, the steam condenses and the bubbles burst. The disappearance of the bubbles leads to a local vacuum, and the liquid particles quickly rush to the center of the bubbles. The particles collide with each other and generate a very high local pressure. If the bubbles burst and condense on the metal surface such as the blade, the water will hit the metal surface of the blade with a greater force, causing the blade to be damaged and vibrate. This phenomenon is called cavitation. The shock wave generated by cavitation, coupled with the chemical corrosion of the metal by the trace amount of dissolved oxygen in the liquid, can cause scars and cracks on the surface after a certain period of time, and even gradually fall off in a sponge-like state; when cavitation occurs, noise will also be emitted, which will cause the pump body to vibrate; at the same time, due to the generation of steam, the apparent density of the liquid decreases, so the actual flow rate, outlet pressure and efficiency of the liquid are reduced, and in severe cases, it may lead to the inability to transport liquid.

[0004] Traditional engineering projects using open impellers add skirts to the structure to reduce the destructiveness of impeller clearance cavitation, but this does not fundamentally suppress the generation of axial flow pump clearance cavitation. The vibration, noise and cavitation problems caused by axial flow pump clearance cavitation not only affect the energy conversion of the water pump, but also threaten the safe and stable operation and service life of the pump unit. Summary of the invention

[0005] In order to solve the problem that the existing open impeller of a water pump has scars and cracks on its surface due to gap cavitation, and even gradually falls off in a sponge-like state and makes noise, thereby causing the pump body to vibrate, the present invention provides an open impeller of a water pump that can suppress gap cavitation. The geometric shape of the impeller water inlet edge is optimized, the flow characteristics at the rim gap of the water pump impeller water inlet edge are improved, the flow velocity of the impeller tip gap is reduced, and the tip gap pressure is increased to be higher than the minimum pressure on the blade surface, thereby achieving the purpose of suppressing the gap cavitation of the axial flow pump impeller, thereby solving the problems raised in the above-mentioned background technology.

[0006] The technical solution of the present invention is:

[0007] An open impeller for a water pump capable of suppressing gap cavitation comprises an impeller hub and blades, wherein a plurality of blades are evenly arranged circumferentially on the impeller hub;

[0008] The side of the blade facing the water pipe is the water inlet side, and the side of the blade corresponding to the downstream diffuser is the water outlet side. The intersection of the water inlet side and the rim surface is A, and the intersection of the water inlet side and the hub surface is B. The impeller rim side wrap angle formed by the intersection point A and the vertical line and longitudinal plane of the impeller hub axis is φ A The impeller hub side angle formed by the intersection point B, the perpendicular line of the impeller hub axis and the longitudinal plane is φ B , and φ A Greater than φ B , where φ A With φ B The difference is 10°~30°;

[0009] Furthermore, the φ A With φ B The difference is 14°~21°.

[0010] Furthermore, the φ A With φ B The difference is 18°.

[0011] Furthermore, the number of the blades is 3 to 7.

[0012] Furthermore, the impeller hub is arranged in a shuttle shape at one end of the downstream diffuser.

[0013] Furthermore, the impeller hub and blades are formed by casting.

[0014] Furthermore, the impeller hub and blades are made of cast iron.

[0015] Also included is an open impeller pump, including a runner chamber and a water pump open impeller. The water pump open impeller is concentrically installed in the annular runner chamber. The gap between the rim surface of the water pump open impeller and the inner wall of the runner chamber is 0.05% of the impeller diameter.

[0016] Furthermore, the wheel chamber is made of cast iron.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. An open impeller for a water pump and an open impeller pump capable of suppressing clearance cavitation. The positive wrap angle difference ⊿φ between the position of the water inlet edge 3 of the blade 2 on the hub surface and the rim surface is designed to be greater than 18° (⊿φ=φ A -φ B), the blade water inlet edge 3 wheel edge can contact the inflow before the other parts of blade 2. At the impeller water inlet edge 3 wheel edge position where gap cavitation is easy to occur, the gap flow caused by the pressure difference between the front and back sides of the impeller is suppressed, the flow velocity at the water inlet edge blade tip gap is reduced, the pressure at the gap is increased, the necessary cavitation margin of the runner is reduced, the wheel edge gap cavitation is suppressed, and the unit operation stability is improved.

[0019] 2. The present invention makes the water inlet rim side of the open impeller, which is prone to cavitation, closer to the high-pressure surface of the impeller blades, thereby increasing the environmental pressure of the water inlet rim surface and playing a role in suppressing cavitation in the runner gap. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a longitudinal sectional view of the open center impeller pump of the present invention;

[0021] Figure 2 It is a structural schematic diagram of the open center impeller pump of the present invention;

[0022] Figure 3 The structure of the open center impeller of the present invention is shown in FIG. Figure I ;

[0023] Figure 4 The structure of the open center impeller of the present invention is shown in FIG. Figure II ;

[0024] Figure 5 The relationship curve between the positive wrap angle difference ⊿φ between the water inlet edge of the blade and the hub and the cavitation coefficient of the pump.

[0025] In the figure: 1. impeller hub; 2. blades; 3. water inlet edge; 4. water outlet edge; 5. impeller chamber; 6. hub surface; 7. rim surface. DETAILED DESCRIPTION

[0026] Specific implementation method 1: See Figure 1-4 As shown, an open impeller for a water pump capable of suppressing gap cavitation, this embodiment comprises an impeller hub 1 and blades 2, and a plurality of blades 2 are evenly arranged circumferentially on the impeller hub 1;

[0027] The side of blade 2 facing the water flow from the water pipe is the water inlet edge 3, and the side of blade 2 corresponding to the downstream diffuser is the water outlet edge 4. The intersection of water inlet edge 3 and rim surface 7 is A, and the intersection of water inlet edge 3 and hub surface 6 is B. The impeller rim side wrap angle formed by the intersection A and the vertical line and longitudinal plane of the impeller hub 1 axis is φ A The impeller hub side angle formed by the intersection point B and the vertical line and the longitudinal plane of the impeller hub 1 axis is φ B , and φ A Greater than φ B , where φ A With φ B The difference is 10°~30°.

[0028] Specific implementation method 2: See Figure 1-4 As shown, the φ A With φ B The difference is 14°~21°.

[0029] Specific implementation method three: see Figure 1-4 As shown, the φ A With φ B The difference is 18°.

[0030] Specific implementation method four: see Figure 1-4 As shown, the number of the blades 2 in this embodiment is 3 to 7.

[0031] Furthermore, the water inlet edge changes continuously in an arc shape from point A to point B; except for point A to point B, the position angles of other points on the water inlet edge change monotonically and continuously.

[0032] When the water inlet edge 3 of the blade 2 has a large positive wrap angle difference ⊿φ between the position of the rim surface and the position of the hub surface (⊿φ=φ A -φ B ), the rim of the blade inlet edge 3 can contact the incoming flow before other parts of the blade 2. At the rim of the impeller inlet edge 3 where gap cavitation is prone to occur, the gap flow caused by the pressure difference between the front and back sides of the impeller is suppressed, the flow velocity at the gap at the water inlet edge is reduced, the pressure at the gap is increased, the necessary cavitation margin of the runner is reduced, the rim gap cavitation is suppressed, and the unit operation stability is improved. When the blade 2 rotates and does work on the fluid, according to the flow velocity on the surface of the blade 2, the working surface of the blade 2 is called the high-pressure surface and the non-working surface is called the low-pressure surface. The pressure difference between the high-pressure surface and the low-pressure surface causes gap flow between the runner rim surface 7 and the runner chamber 5. When φ A With φ B When the difference is not less than 18°, it can effectively suppress the influence of the pressure difference between the front and back sides of the blade on the flow in the gap near the rim of the impeller water inlet edge 3, suppress the cavitation of the runner gap, and improve the operating stability of the unit.

[0033] Combination Figure 5 : The relationship curve between the positive wrap angle difference ⊿φ between the blade inlet edge and the hub and the pump cavitation coefficient. When ⊿φ is around 18 degrees, the pump open impeller obtains the minimum cavitation coefficient, and compared with the pump open impeller corresponding to ⊿φ<0, where the inlet edge hub first meets the incoming flow, the cavitation coefficient is significantly reduced.

[0034] Specific implementation method five: see Figure 1-4 As shown, the impeller hub 1 of this embodiment is arranged in a shuttle shape at one end of the downstream diffuser.

[0035] Specific implementation method six: see Figure 1-4As shown, the impeller hub 1 and blades 2 of this embodiment are formed by casting.

[0036] Specific implementation method seven: See Figure 1-4 As shown, the impeller hub 1 and blades 2 of this embodiment are made of cast iron.

[0037] Specific implementation method eight: See Figure 1-4 As shown, an open impeller pump using the open impeller of one of claims 1-7, this embodiment includes a runner chamber 5 and an open impeller of the water pump, the open impeller of the water pump is concentrically installed in the annular runner chamber 5, and the gap between the rim surface 7 of the open impeller of the water pump and the inner wall of the runner chamber 5 is 0.05% of the impeller diameter.

[0038] Specific implementation method nine: See Figure 1-4 As shown, the wheel chamber 5 of this embodiment is made of cast iron.

[0039] Furthermore, the gap between the rim surface 7 of the open impeller of the water pump and the inner wall of the runner chamber 5 is 0.05% of the impeller diameter, so that the leakage at the runner gap is minimized while effectively suppressing cavitation.

[0040] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. An open impeller for a water pump capable of suppressing clearance cavitation, characterized in that: It comprises an impeller hub (1) and blades (2), wherein a plurality of blades (2) are evenly arranged circumferentially on the impeller hub (1); The side of the blade (2) facing the flow from the water diversion pipe is the water inlet edge (3), and the side of the blade (2) corresponding to the downstream diffuser is the water outlet edge (4). The intersection point of the water inlet edge (3) and the rim surface (7) is A, and the intersection point of the water inlet edge (3) and the hub surface (6) is B. The impeller rim side wrap angle formed by the intersection point A and the perpendicular line and the longitudinal plane of the impeller hub (1) axis is φ. A The impeller hub side angle formed by the perpendicular line and the longitudinal plane of the intersection point B and the impeller hub (1) axis is φ B , and φ A Greater than φ B , where φ A With φ B The difference is 10°~30°.

2. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The φ A With φ B The difference is 14°~21°.

3. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The φ A With φ B The difference is 18°.

4. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The number of the blades (2) is 3 to 7.

5. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The impeller hub (1) is arranged in a shuttle shape at one end of the downstream diffuser.

6. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The impeller hub (1) and the blades (2) are formed by casting.

7. The open impeller of a water pump capable of suppressing clearance cavitation according to claim 1, characterized in that: The impeller hub (1) and the blades (2) are made of cast iron.

8. An open impeller pump using the open impeller of a water pump according to any one of claims 1 to 7, characterized in that: The invention comprises a runner chamber (5) and an open impeller of a water pump. The open impeller of the water pump is coaxially installed in the annular runner chamber (5). The clearance between the rim surface (7) of the open impeller of the water pump and the inner wall of the runner chamber (5) is 0.05% of the diameter of the impeller.

9. The open impeller pump according to claim 8, characterized in that: The wheel chamber (5) is made of cast iron.

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