CN106640769A - Conical water inflow device for improving instability hydraulic characteristic of axial flow pump - Google Patents

Abstract

The invention discloses a conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump. The two ends of an outer casing are respectively an inlet end and an outlet end. The inlet end of the flow pump impeller chamber is connected by an outlet flange, the outer wall of the inlet end of the outer casing is provided with an inlet flange, and the inlet end of the outer casing can be connected with the water inlet pipe through the inlet flange; the outer casing is provided with an inner casing, and the inner casing 1. There is a gap between the outer casing, and a rib is arranged in the gap, through which the inner and outer casings are fixedly connected, and a vortex-eliminating plate is arranged on the inner wall of the inner casing. The invention fully improves the inflow condition in front of the impeller under the working condition of small flow rate, completely eliminates the hydraulically unstable "saddle area" of the axial flow pump, and effectively widens the range of safe and stable operating conditions of the axial flow pump. The structure of the invention is simple and easy to manufacture, and is suitable for any type of axial flow pump.

Description

A Conical Water Inlet Device for Improving the Unstable Hydraulic Characteristics of Axial Flow Pumps

technical field

The invention belongs to the technical field of water pumps, and in particular relates to a conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump.

Background technique

Axial flow pumps have the characteristics of large flow and low head, and are widely used in fields such as cross-basin water transfer, agricultural irrigation, and municipal water supply and drainage. Under the design conditions, the axial flow pump has good water inlet conditions and stable internal flow. At this time, the hydraulic efficiency of the pump is high and the operation is stable. However, under non-design conditions, especially low flow conditions, the change of the inflow angle at the impeller inlet not only causes flow separation at the inlet edge on the back of the blade, but also increases the pressure difference between the upper and lower surfaces of the blade and enhances the tip clearance leakage flow. The flow direction of the separation flow at the back of the blade and the leakage flow at the tip of the impeller is opposite to the main flow direction. At the same time, due to the influence of the rotation of the impeller, the above flow has a relatively large circumferential velocity, thereby blocking the inlet flow channel of the impeller and deteriorating the inlet flow conditions of the pump. It causes the hydraulic loss of the pump to increase and the performance of the pump to decline sharply, which promotes the formation of the hydraulically unstable "saddle area", which seriously affects the safe and stable operation of the axial flow pump.

Contents of the invention

The purpose of the present invention is to address the shortcomings of the existing axial flow pump water inlet device, and propose a conical water inlet device that improves the unstable hydraulic characteristics of the axial flow pump, without affecting the hydraulic pressure of the pump under the design flow and large flow conditions. When the performance is greatly affected, it can fully improve the water inlet conditions before the inlet of the impeller of the axial flow pump under the condition of small flow rate, completely eliminate the unstable "saddle area" of the axial flow pump, and effectively expand the stable operation of the axial flow pump Working condition interval.

For realizing the purpose of the present invention, adopt following technical scheme:

A conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump, comprising an outer sleeve, the two ends of the outer sleeve are respectively an inlet end and an outlet end, and the outer wall of the outlet end is provided with an outlet flange, and the outlet flange is along the circumference 4 to 12 screw holes are evenly distributed, and the outlet end of the outer casing is connected to the inlet end of the impeller chamber of the axial flow pump through an outlet flange, and the diameter D of the outlet end of the outer casing is equal to the diameter of the inlet end of the impeller chamber of the axial flow pump;

The outer wall of the inlet end of the outer casing is provided with an inlet flange, and the inlet flange is evenly distributed with 4 to 12 screw holes along the circumference, and the inlet end of the outer casing can be connected to the water inlet pipe through the inlet flange;

The outer casing is provided with an inner casing, and there is a gap between the inner casing and the outer casing, and a rib plate is arranged in the gap, through which the inner casing and the outer casing are fixedly connected, and the inner wall of the inner casing is provided with a vortex elimination plate.

The outer wall surface of the above-mentioned inner casing and the inner wall surface of the outer casing are connected by 4 to 6 ribs evenly arranged along the circumferential direction; 6 to 18 vortex elimination plates are evenly arranged along the circumferential direction on the inner wall of the inner casing; The inlet and outlet edges of the ribs are all rounded to reduce the impact loss of water flow.

The structure and position dimensions of the outer casing, inner casing, rib plate and vortex-eliminating plate of the present invention are expressed by relative values based on the outlet diameter D of the outer casing, and these relative values can be multiplied by the outlet diameter D of the outer casing. Get the actual size of the application of the present invention.

Preferably, the outlet of the outer casing is connected to the inlet of the impeller chamber of the axial flow pump through a flange, and the outlet diameter D of the outer casing is equal to the inlet diameter of the impeller chamber of the axial flow pump; the cone angle of the outer casing is 5-60 °, the diameter of the inlet is 1.05-5D, and the height is 0.05-3D; the inlet of the outer casing can be opened, and can also be connected to the water inlet pipe through a flange.

As a preferred technical solution of the present invention, both the outer sleeve and the inner sleeve are conical structures with the same taper, and the diameter of the inlet end is larger than that of the outlet end.

Further, the thickness of the inner sleeve is 0.001-0.01D, and the distance between the inner sleeve and the outer sleeve is 0.005-0.1D.

Further, the inlet end of the inner casing is flush with the inlet end of the outer casing, the outlet end of the inner casing is higher than the outlet end of the outer casing, and after the outer casing is connected to the impeller chamber of the axial flow pump, the outlet of the inner casing The end is close to the top of the impeller; the inlet and outlet ends of the inner casing are rounded.

Furthermore, the circumference of the vortex elimination plate is evenly distributed on the inner wall of the inner casing, the vortex elimination plate is a fan-shaped structure, and the angle between the two sides in the circumferential direction is 5 to 20°; the length of the vortex elimination plate and the inner sleeve The lengths of the busbars on the inner wall of the tube are equal, and the thickness of the vortex-eliminating plate is 0.01-0.2D.

Preferably, the width of the ribs is 0.001-0.005D; the length of the ribs is equal to the length of the generatrix of the inner wall of the casing.

The above-mentioned outer sleeve, inlet flange, outlet flange, inner sleeve, rib plate and vortex-eliminating plate of the present invention can be made of metal materials, plastic materials or plexiglass materials.

The present invention is based on fluid dynamics theory and axial flow pump design theory, and on the basis of experimental measurement and numerical simulation analysis of the internal complex flow of axial flow pump under small flow conditions, a simple, scientific and reasonable structure is proposed. Water inlet device.

The beneficial effects of the present invention are:

The inner sleeve in the present invention can separate the leakage flow at the tip of the blade from the main flow at the center of the impeller, preventing the leakage flow from the tip clearance from hindering the main flow. The hydraulic loss caused by the vertical velocity; the uniformly distributed vortex-eliminating plates on the inner wall of the inner casing can play a role in weakening the circumferential rotational flow in front of the impeller inlet. Therefore, the present invention fully improves the inflow condition in front of the impeller under low flow conditions, completely eliminates the hydraulically unstable "saddle area" of the axial flow pump, and effectively expands the range of safe and stable operating conditions of the axial flow pump. The structure of the invention is simple and easy to manufacture, and is suitable for any type of axial flow pump.

Description of drawings

Fig. 1 is a schematic sectional view of the structure of the present invention;

Fig. 2 is a structural top view of the present invention;

Fig. 3 is a schematic diagram of the cross-sectional structure size of the present invention;

Fig. 4 is a schematic diagram of planar structure dimensions of the present invention;

Fig. 5 is the assembly schematic diagram of the embodiment of the present invention;

Fig. 6 is a comparative diagram of the hydraulic performance of the axial flow pump before and after adopting the present invention.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

As shown in the figure, the present invention relates to an outer casing 1, an inlet flange 2, an outlet flange 3, an inner casing 4, a rib plate 5, a vortex elimination plate 6, an impeller 7, an impeller chamber 8, an impeller chamber inlet flange 9, Technical features such as wheel hub 10, pump shaft 11.

As shown in Figures 1 and 2, a conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump includes an outer casing 1, the two ends of the outer casing 1 are the inlet end and the outlet end, and the outer wall of the outlet end is provided with Outlet flange 3, the outlet end of the outer casing 1 is connected to the inlet end of the impeller chamber of the axial flow pump through the outlet flange 3, and the diameter D of the outlet end of the outer casing 1 is equal to the diameter of the inlet end of the impeller chamber of the axial flow pump;

The outer wall of the inlet end of the outer casing 1 is provided with an inlet flange 2, and the inlet end of the outer casing 1 can be connected to the water inlet pipe through the inlet flange 2;

The outer sleeve 1 is provided with an inner sleeve 4, and there is a gap between the inner sleeve 4 and the outer sleeve 1, and a rib plate 5 is arranged in the gap, and the inner sleeve 4 is fixedly connected with the outer sleeve 1 through the rib plate 5. A vortex-eliminating plate 6 is arranged on the inner wall of the casing 4 .

The outer casing 1, the inlet flange 2, the outlet flange 3, the inner casing 4, the rib plate 5 and the vortex elimination plate 6 can be made of metal materials, plastic materials or plexiglass materials.

The structure and position dimensions of the outer casing 1, inner casing 4, rib plate 5 and vortex-eliminating plate 6 are expressed by relative values based on the outlet diameter D of the outer casing 1, and these relative values are multiplied by the outlet diameter D of the outer casing 1 The actual size of the application of the present invention can be obtained.

As shown in FIG. 3 and FIG. 4 , both the outer sleeve 1 and the inner sleeve 4 are conical structures with the same taper, and the diameter of the inlet end is larger than that of the outlet end. The cone angle α of the outer casing 1 is 5-60°, the inlet diameter D1 is 1.05-5D, and the height H is 0.05-3D; the inlet of the outer casing can be opened for use, and can also be connected to the water inlet pipe through a flange; the inlet method The flange 2 has 4 to 12 screw holes evenly distributed along the circumference, and the outlet flange 3 has 4 to 12 screw holes evenly distributed along the circumference; the inner sleeve 4 is located inside the outer sleeve 1 and the surfaces of the two are parallel, the gap formed The vertical distance T1 is 0.005-0.1D; the inlet side of the inner casing 4 is flush with the inlet side of the outer casing 1; the outlet side of the inner casing 4 is higher than the outlet side of the outer casing 1; the inlet and outlet sides of the inner casing 4 The edges of the outlet are all rounded to reduce the impact loss of water flow; the thickness T3 of the inner sleeve 4 is 0.001-0.01D; the outer wall of the inner sleeve 4 and the inner wall of the outer sleeve 1 pass through 4-6 ribs evenly arranged along the circumferential direction The ribs 5 are connected; the inlet and outlet edges of the ribs 5 are rounded to reduce the impact loss of the water flow; the width T2 of the ribs 5 is 0.001-0.005D; the length of the ribs is equal to the length of the inner wall of the outer casing, L1; 6-18 vortex-eliminating plates 6 are evenly arranged along the circumferential direction on the inner wall of the inner sleeve 4; the corresponding angle θ of the vortex-eliminating plates 6 in the circumferential direction is 5-20°; The generatrices of the walls have the same length, which is L2, and the thickness T4 of the vortex-eliminating plate is 0.01-0.2D.

Example 1

As shown in Figure 5, wherein, the outlet of the outer casing 1 is connected to the inlet flange 9 of the impeller chamber through the flange 3, the diameter D of the inlet of the outer casing is equal to 290mm of the inlet diameter of the impeller chamber 8, and the cone angle of the outer casing 1 is 15°, height The inlet diameter is 230mm and the inlet diameter is 350mm. The inlet flange of the outer casing is connected to the water inlet pipe. The distance between the inner casing 4 and the outer casing 1 is 5mm and connected by four circumferentially evenly distributed ribs 5. The thickness of the inner casing 4 is 1.2mm. , the rib plate 5 has a width of 2 mm, and 12 vortex-eliminating plates 6 are evenly distributed along the circumferential direction on the inner wall of the inner sleeve. The corresponding angle of the vortex-eliminating plates 6 in the circumferential direction is 10° and the thickness is 10 mm. The edge distance is 8mm.

As shown in Figure 6, using the three-dimensional flow numerical simulation method, comparing and analyzing the hydraulic performance curves of the axial flow pump device before and after the adoption of the present invention, it can be found that the conical water inlet device of the present invention can eliminate the unstable "" in the hydraulic performance of the axial flow pump Saddle area", so as to ensure the stable operation of the axial flow pump under the full flow condition, and effectively expand the safe and stable operating condition range of the axial flow pump.

Claims (9)

1. A conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump, characterized in that it includes an outer casing (1), the two ends of the outer casing (1) are respectively an inlet end and an outlet end, and the outer wall of the outlet end is provided with There is an outlet flange (3), the outlet end of the outer casing (1) is connected to the inlet end of the impeller chamber of the axial flow pump through the outlet flange (3), and the diameter D of the outlet end of the outer casing (1) is equal to the impeller chamber of the axial flow pump The diameter of the inlet port; The outer wall of the inlet end of the outer casing (1) is provided with an inlet flange (2), and the inlet end of the outer casing (1) can be connected to the water inlet pipe through the inlet flange (2); The outer casing (1) is provided with an inner casing (4), and there is a gap between the inner casing (4) and the outer casing (1), and a rib (5) is arranged in the gap, through which the rib (5) will The inner sleeve (4) is fixedly connected with the outer sleeve (1), and the inner wall of the inner sleeve (4) is provided with a vortex elimination plate (6). 2. The tapered water inlet device for improving the unstable hydraulic characteristics of the axial flow pump according to claim 1, characterized in that: the outer casing (1) and the inner casing (4) are both tapered structures with the same taper, The diameter of the inlet port is larger than that of the outlet port. 3. The conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump according to claim 2, characterized in that: the cone angle of the outer casing (1) is 5-60°, the height is 0.05-3D, and the outer casing (1) (1) The diameter of the inlet end is 1.05-5D. 4. The conical water inlet device for improving the unstable hydraulic characteristics of an axial flow pump according to claim 3, characterized in that: the thickness of the inner casing (4) is 0.001-0.01D, and the inner casing (4) The distance from the outer casing (1) is 0.005-0.1D. 5. The conical water inlet device for improving the unstable hydraulic characteristics of the axial flow pump according to claim 2, characterized in that: the inlet end of the inner casing (4) is flush with the inlet end of the outer casing (1) , the outlet end of the inner sleeve (4) is higher than the outlet end of the outer sleeve (1), after the outer sleeve (1) is connected to the impeller chamber of the axial flow pump, the outlet end of the inner sleeve (4) is close to the top of the impeller; The inlet and outlet ends of the inner casing (4) are rounded. 6. The conical water inlet device for improving the unstable hydraulic characteristics of the axial flow pump according to claim 2, characterized in that: the vortex elimination plate (6) is evenly distributed on the inner wall of the inner casing (4), and the vortex elimination The plate (6) has a fan-shaped structure, and the angle between the two sides in the circumferential direction is 5-20°; The thickness is 0.01-0.2D. 7. The conical water inlet device for improving the unstable hydraulic characteristics of the axial flow pump according to claim 1, characterized in that: the inlet flange (2) has 4 to 12 screw holes evenly distributed along the circumference. 8. The conical water inlet device for improving the unstable hydraulic characteristics of the axial flow pump according to claim 1, characterized in that: the outlet flange (3) has 4 to 12 screw holes evenly distributed along the circumference. 9. The conical water inlet device for improving the unstable hydraulic characteristics of axial flow pumps according to claim 1, characterized in that: the width of the ribs (5) is 0.001-0.005D, and the length of the ribs (5) It is equal to the busbar length of the inner wall of the outer sleeve (1).