CN104481918B - Mixed flow impeller with suction side back blade - Google Patents

Abstract

The invention relates to a mixed flow pump, and in particular relates to a mixed flow impeller with a suction side back blade. The mixed flow impeller with the suction side back blade is characterized in that the suction side back blade is arranged between every two adjacent blades in a running channel of the mixed flow impeller; the suction side back blade is separated from a blade working surface and is mounted on the back surface of the blade. According to the mixed flow impeller with the suction side back blade, the suction side back blade is arranged in the running channel of the impeller and can be used for highly stopping any adverse axial flowing, so as to lower down the velocity gradient in the running channel; therefore, the uniformity of the structure of a flowing field of the running cannel of the impeller can be raised, and as a result, the performance of the pump can be further improved.

Description

A mixed flow impeller with auxiliary blades on the suction surface

technical field

The invention relates to a mixed-flow pump, in particular to a mixed-flow impeller with auxiliary blades on a suction surface.

Background technique

Mixed-flow pumps play an important role in various fields of the national economy. Its shape is between centrifugal pumps and axial-flow pumps. It has the advantages of large flow and high lift. It also consumes a lot of electricity, so the performance of mixed-flow pumps can be improved. It is of great significance to the construction of a new energy-saving society. The impeller profile of the mixed-flow pump presents a complex and distorted shape in space, the geometric parameters are extremely complex, and the design is difficult. At the same time, the mutual influence relationship between various parameters has not been fully clarified. Therefore, the efficient mixed-flow impeller design has become an important part of the mixed-flow pump design. The difficult problem is that the fluid inside the mixed-flow impeller is affected by the centrifugal force and the lift force, and its motion state is more complicated than that of the centrifugal pump and the axial flow pump. How to make the fluid move smoothly along the blade profile and reduce the hydraulic loss inside the impeller becomes the key to improving pump performance. key issues.

From the relative flow velocity distribution diagram of the conventional mixed flow impeller outlet in Figure 5, it can be seen that the relative flow velocity close to the rear cover of the impeller is much greater than the relative flow velocity close to the front cover of the impeller, and a large velocity gradient is easy to form a vortex structure, resulting in a large hydraulic losses, reducing pump performance. Therefore, how to control the poor flow structure inside the impeller of the mixed flow pump and reduce the velocity gradient inside has a very significant impact on reducing hydraulic loss and improving pump performance.

At present, the research on mixed-flow impellers mainly focuses on the optimization of blade profile, geometric parameters, number of blades and other factors. Guan Xingfan, Lu Weigang, Shi Weidong and others have studied the influence of impeller geometric parameters on pump performance. At present, most of the research starts from optimizing the geometric parameters of the impeller and explores the influence of different parameter ratios on the performance of the pump. It fails to start from controlling the bad flow structure of the mixed-flow impeller to reduce the hydraulic loss inside the impeller, so that the energy performance of the pump can be further improved. Therefore, the control of the harmful flow structure inside the mixed-flow impeller has practical significance for improving the performance of the pump.

Contents of the invention

In order to further improve the performance of the mixed-flow pump, the present invention proposes a mixed-flow impeller with auxiliary blades on the suction surface from the perspective of controlling the bad axial flow inside the mixed-flow impeller. The structure of the impeller is simple and reasonable, and the velocity gradient inside the impeller is effectively reduced. , evenly reconstruct the flow field distribution inside the impeller, reduce the hydraulic loss of the impeller, and further improve the performance of the mixed flow pump.

The invention provides a mixed flow impeller with auxiliary blades on the suction surface.

The auxiliary blade on the suction side is located between two adjacent blades in the channel of the mixed-flow impeller, separated from the working surface of the blade, installed on the back of the blade, and distributed evenly along the circumference. same.

The outlet of the auxiliary blades on the suction surface is flush with the outlet of the impeller, the thickness is uniform, and equal to the average thickness of the blades, and the number of them is the same as that of the impeller blades.

The auxiliary blades on the suction side are far away from the front cover of the impeller and closer to the rear cover of the impeller, and the distance between the outlet edge and the rear cover of the impeller is 1/4~1/2 of the width of the impeller outlet.

The circumference length a of the outlet side of the auxiliary blade on the suction surface is 1/4~3/4 of the arc length between adjacent blades, and the ratio of the circumference length b of the inlet side to the circumference length of the flow channel where the inlet side is located is the same as that of the outlet side. The radial length c is 1/4~3/4 of the radial length d of the blade.

This structure reduces the velocity gradient by controlling the harmful axial flow of the liquid in the flow channel of the mixed-flow impeller, so as to realize the uniform reconstruction of the flow field inside the impeller, reduce the hydraulic loss, and achieve the purpose of improving the performance of the pump.

The advantages of the present invention are: starting from controlling the bad axial flow inside the impeller, by arranging the auxiliary vane structure of the suction surface in the impeller flow channel, the bad axial flow is forcibly blocked, the velocity gradient in the flow channel is reduced, and the flow rate of the impeller flow channel is reduced. The flow field structure is more uniform, further improving the performance of the pump. Simultaneously, the invention also has the advantages of simple and reasonable structure, convenient processing and the like.

Description of drawings

Fig. 1 is an axial plane projection view of the mixed flow impeller with auxiliary blades on the suction side of the present invention.

Fig. 2 is a plan projection view of the mixed flow impeller with auxiliary blades on the suction side of the present invention.

Fig. 3 is a plan development view of the cross-section of the outlet channel of the mixed-flow impeller with auxiliary blades on the suction side of the present invention.

Fig. 4 is a structural diagram of the relative flow velocity distribution at the outlet of the mixed flow impeller with auxiliary blades on the suction side of the present invention.

Fig. 5 is a structural diagram of relative flow velocity distribution at the outlet of a traditional mixed flow impeller.

detailed description

The present invention will be further described below in conjunction with accompanying drawing.

Figure 1 shows the axial plane projection of the mixed flow impeller. It can be seen from the figure that the auxiliary blade 3 on the suction side is far away from the front cover 1 of the impeller and is closer to the rear cover 2 of the impeller, and its axial shape is the same as the streamline shape of the rear cover. , the distance from the outlet edge to the back cover of the impeller is 1/2 of the width of the impeller outlet, and its radial length is 1/2 of the radial length of the blade.

It can be seen from Figure 2 that the auxiliary blades on the suction surface are connected to the back side of the blade 5 and separated from the working surface 4 of the blade. , its thickness is equal to the average thickness of the blade, which is taken as 4mm, and its outlet edge is flush with the impeller outlet 6.

Figure 3 shows the plane expansion diagram of the flow section of the impeller outlet channel. The circumference length a of the outlet side of the auxiliary blade on the suction surface is 65.2% of the arc length between adjacent blades, and the circumference length b of the inlet side is also the inlet side 65.2% of the circumferential length of the flow channel, and its radial length is 50% of the radial length of the blade.

Figure 5 shows the distribution structure of the relative flow velocity at the outlet of the traditional mixed-flow impeller. It is known that the relative flow velocity close to the back cover of the impeller is much greater than the relative flow velocity close to the front cover of the impeller. A large velocity gradient is easy to form a vortex structure, resulting in a large hydraulic losses, reducing pump performance.

It can be seen from Figure 4 that after adding auxiliary blades on the suction surface, the axial flow inside the impeller is forcibly blocked, the distribution of the flow field at the outlet of the impeller is more uniform, and the velocity gradient is small, so the hydraulic loss inside the impeller can be effectively reduced and the performance of the whole pump can be improved. . Therefore, controlling the flow structure inside the impeller of the mixed-flow pump and reducing the velocity gradient inside it have an extremely significant impact on reducing hydraulic loss and improving pump performance.

In this example, the CFD method is used to predict the performance of the pump. Under the same impeller and volute conditions, at the design point of the mixed flow pump, after adopting the auxiliary blade structure on the suction surface, the lift of the mixed flow pump is basically unchanged, and the efficiency is increased by 2.5%. .

The invention improves the internal flow structure of the impeller so as to reduce the internal flow loss of the pump and further improve the performance of the pump.

Claims (1)

1. a kind of mixed flow impeller with suction surface back vane it is characterised in that：In mixed flow impeller runner between adjacent two blades It is provided with suction surface back vane, suction surface back vane is separated with front side of vane, be arranged on vacuum side of blade, by impeller channel Interior arrangement suction surface back vane structure, blocks bad axial direction flowing by force, reduces the velocity gradient in runner, make impeller stream The flow field structure in road is more uniform, improves the performance of pump further；Described suction surface back vane is uniformly distributed along the circumference, its number and leaf Impeller blade number is identical, and the axial plane shape of suction surface back vane is identical with back shroud of impeller streamline；Described suction surface back vane outlet Flush with impeller outlet, thickness is uniform, and suitable with blade average thickness；Described suction surface back vane away from front shroud of impeller, Closer to back shroud of impeller, the distance of its outlet back gauge back shroud of impeller is the 1/4～1/2 of impeller outlet width；Described suction The circumferential length a that power face back blades exports side is 1/4～3/4 of arc length between adjacent blades, and its inlet side circumferential length b accounts for The ratio of inlet side place runner circumferential length is identical with outlet side, and its radical length c is the 1/4～3/ of blade radial length d 4.