Double-layer pressurizing axial flow impeller and axial flow pump rotor adopting same

Abstract

The axial flow impeller comprises an impeller body, the impeller body comprises an inner wheel column and a plurality of inner-layer blades arranged on the outer side of the inner wheel column in the circumferential direction, an outer wheel column connected with the outer ends of the inner-layer blades is arranged on the outer sides of the inner-layer blades, and the inner-layer blades are arranged on the outer side of the outer wheel column. A plurality of outer-layer blades are arranged on the outer side of the outer wheel column in the circumferential direction; the inner-layer blades and the outer-layer blades are arc-shaped and face opposite directions; the axial flow pump rotor comprises a rotating shaft and at least one axial flow impeller fixedly connected to the rotating shaft in a sleeving mode, and the axial stress of the axial flow pump rotor meets the following formula: iFZ1 + G = iFZ2 + FT + FF.

Description

Technical Field

[0001] The invention relates to the field of axial flow pumps, and in particular to a double-layer pressurized axial flow impeller and an axial flow pump rotor using the impeller. Background Art

[0002] Axial flow pumps are mainly suitable for low head and large flow occasions, such as water jet propulsion of ships, dock drainage, water level regulation of canal locks, etc., and are often used as large circulating water pumps in power plants. Since the blades of axial flow pumps are usually cantilever structures, fatigue failure and other strength problems may occur when they are under heavy load and periodic unstable operation. On the other hand, with the development needs of society, higher requirements are put forward for the reliability and stability of axial flow pumps, which need to meet the stable use in high speed and high load operation occasions. The existing axial flow pump impeller is mainly composed of an inner wheel column and a plurality of blades arranged circumferentially on the outer side of the inner wheel column. The blades are arranged in an arc shape and are arranged in the same direction clockwise or counterclockwise. If this impeller wants to increase its head, it needs to be achieved by increasing the impeller diameter, increasing the number of blades, changing the blade angle, and using a bipolar or multi-stage impeller. However, too many blades will increase fluid resistance and reduce efficiency. If the impeller diameter is too large or a multi-stage impeller is used, the weight and volume of the pump will be increased, and the head that can be increased by changing the blade angle is also relatively limited. Based on this, the applicant wants to design an axial flow impeller that does not need to increase the number of impellers and the diameter of the impeller, and increases the impeller head by setting two layers of impellers. If a double-layer impeller is used for supercharging, it is necessary to ensure that the axial force generated by the inner and outer layers of blades is zero, and to ensure that the axial force of the axial flow pump rotor is balanced. However, there is no such structure in the prior art. If it is set to achieve zero axial force of the axial flow pump rotor, it is an urgent problem to be solved. Summary of the invention

[0003] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a double-layer pressurized axial flow impeller and an axial flow pump rotor using the impeller, so as to solve the problems that the existing axial flow impeller has a single structure, the head needs to be improved, and the axial force of the axial flow pump rotor is unbalanced.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0005] A double-layer supercharged axial flow impeller includes an impeller body, the impeller body includes an inner wheel column and a plurality of inner blades circumferentially arranged on the outer side of the inner wheel column, an outer wheel column connected to the outer end of the inner blade is arranged on the outer side of the inner wheel column, and a plurality of outer blades are circumferentially arranged on the outer side of the outer wheel column; the inner blades and the outer blades are both arc-shaped and face in opposite directions. After adopting the above structure, the axial flow impeller has two layers of impellers, namely, the inner blades and the outer blades located on the inner and outer sides of the outer wheel column, respectively, the inner blades and the outer blades are arc-shaped, and are respectively arranged clockwise and counterclockwise with respect to the center of the inner wheel column. In this way, during operation, the external flow water first enters the outer blades, and then enters the position of the inner blades under the stirring and guidance of the blades, the water flow process is increased, and at the same time, because the outer blades and the outer blades face in opposite directions, the water flow is disturbed twice during the same direction rotation, and the disturbance direction is different, and the head generated is also greater. The inner wheel column can be used to cooperate with the rotating shaft and set the inner blades, while the outer wheel column can not only increase the compressive strength of the impeller body, but also be used to install the outer blades and connect the inner blades and the outer blades to form a whole.

[0006] Furthermore, the cross-sectional shapes of the inner blades and the outer blades are airfoil-shaped. The blade shape is set to be airfoil-shaped, and the overall strength is high.

[0007] An axial flow pump rotor comprises a rotating shaft and at least one axial flow impeller sleeved and fixed on the rotating shaft, wherein the axial flow impeller is as described above, and the axial force of the axial flow pump rotor satisfies the following formula: iF Z1 +G=iF Z2 +F T +F F ; In the formula, i represents the number of impeller bodies, F Z1 is the reaction force of the fluid on the inner blades, F Z2 is the reaction of the fluid on the outer blades, F T is the pressure difference force on the inner wheel column shaft end, FF is the buoyancy of the impeller body, and G is the deadweight of the axial flow pump rotor. The axial force of the axial flow pump rotor mainly comes from the unbalanced pressure distribution generated by the impeller when it is working. This axial force will place an additional burden on the pump bearings and may even cause the pump to work unstably or be damaged. Therefore, when designing and using axial flow pumps, it is very important to correctly calculate and take measures to balance the axial force. The axial flow pump rotor in this application takes into account the buoyancy, deadweight and pressure received by the inner and outer blades of the axial flow impeller. Under the condition of satisfying the above formula, the pressure on the inner and outer sides is equal, thereby maintaining the force balance of the inner and outer blades during operation, ensuring that the axial flow pump can remain stable.

[0008] Furthermore, Where k is the axial force coefficient of the impeller body, and ρ is the fluid density in kg / m 3 ;H 2is the lift of the outer blades, in m; g is the acceleration due to gravity, D 2 is the diameter of the circle formed by the outer ends of the outer blades, in m; d h2 is the diameter of the outer wheel column, in m;

[0009] In the formula, H 1 is the lift of the inner blades, in m; D 1 is the diameter of the circle formed by the outer ends of the inner blades, in m; d h1 is the diameter of the inner wheel column, in m;

[0010] F T ={iρg(H 1 +H 2 )-p 0}πd 0 2 / 4, where d 0 is the inner diameter of the inner wheel column, p 0 is the absolute pressure at the end of the shaft in the atmospheric environment;

[0011] F F =ρgV, where V is the volume of the axial flow pump rotor immersed in the liquid, in m 3 ;

[0012] G=ρ 0 Vg, where ρ 0 is the material density of the axial flow pump rotor, kg / m 3 . BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematic diagram of the three-dimensional structure of the axial flow impeller in the embodiment;

[0014] Figure 2 It is a structural schematic diagram of the axial flow pump rotor in the embodiment;

[0015] Figure 3 Schematic diagram of fluid operation of the axial flow impeller in the axial flow pump in the embodiment;

[0016] Figure 4 It is a structural schematic diagram of a conventional four-stage axial flow pump in the prior art;

[0017] Figure 5 Schematic diagram of the structure of the double-layer booster impeller axial flow pump in this embodiment under the same operating parameters;

[0018] Figure 6 for Figure 4 and Figure 5 Comparison chart of total head performance curve of axial flow pump;

[0019] Figure 7 for Figure 4 and Figure 5 The comparison of the total axial force curve of the axial flow pump is shown in the figure. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme 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. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. 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 claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present invention.

[0021] It should be noted that similar numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In the description of the present invention, it should be noted that the orientation or position relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention product is usually placed when used, which is 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 of the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance. In addition, the terms "horizontal", "vertical", etc. do not mean that the components are absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted. In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of 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.

[0022] like Figure 1-Figure 3As shown, the axial flow pump rotor provided in this embodiment includes a rotating shaft 1 and at least one axial flow impeller 2 sleeved and fixed on the rotating shaft 1, the axial flow impeller 2 includes an impeller body, the impeller body includes an inner wheel column 21 and a plurality of inner blades 22 circumferentially arranged outside the inner wheel column 21, an outer wheel column 23 connected to the outer end of the inner blade 22 is arranged outside the inner blade 22, and a plurality of outer blades 24 are circumferentially arranged outside the outer wheel column 23; the inner blades 22 and the outer blades 24 are both arc-shaped and face opposite directions; the axial force of the axial flow pump rotor satisfies the following formula: iF Z1 +G=iF Z2 +F T +F F ; In the formula, i represents the number of impeller bodies, F Z1 is the reaction force of the fluid on the inner blade 22, F Z2 is the reaction of the outer blade 24 to the fluid, F T F is the pressure difference force on the shaft end of the inner wheel column 21, F is the buoyancy of the impeller body, and G is the deadweight of the axial flow pump rotor.

[0023] Specifically, Where k is the axial force coefficient of the impeller body, and ρ is the fluid density in kg / m 3 ;H 2 is the lift of the outer blade 24, in m; g is the acceleration due to gravity, D 2 The diameter of the circle formed by the outer ends of the outer blades 24, in meters; d h2 is the diameter of the outer wheel column 23, in m;

[0024] In the formula, H 1 is the lift of the inner blade 22, in m; D 1 The diameter of the circle formed by the outer ends of the inner blades 22, in meters; d h1 is the diameter of the inner wheel column, in m;

[0025] F T ={iρg(H 1 +H 2 )-p 0}πd 0 2 / 4, where d 0 is the inner diameter of the inner wheel column 21, p 0 is the absolute pressure at the end of the shaft in the atmospheric environment;

[0026] F F =ρgV, where V is the volume of the axial flow pump rotor immersed in the liquid, in m 3 ;

[0027] G=ρ 0 Vg, where ρ 0 is the material density of the axial flow pump rotor, kg / m 3 .

[0028] Specifically, D 1 0.35m, d 0 is 0.8m, D2 is 0.495m, d h2 0.38m, d h1 A double-layer impeller axial flow pump with a diameter of 0.185 m (such as Figure 5 Through CFD simulation, the simulation performance data of the axial flow pump designed by this method is shown in the following table:

[0029] Simulation performance data comparison table

[0030]

[0031] Taking the blades with the same curvature as the comparative example, under the same operating environment, the axial flow pump designed by conventional design method (such as Figure 4 As shown in the figure, 4 stages are required to be connected in series (the impeller has four stages, which is the same as the number of stages that can be achieved by the double-layer axial flow impeller in the above embodiment). Through CFD simulation, the simulation performance data of the axial flow pump designed by the conventional method are obtained as follows:

[0032] Simulation performance data comparison table

[0033]

[0034]

[0035] Table 1 The simulation performance data comparison table of the double-layer booster impeller axial flow pump in the above comparative example and the present embodiment is as follows:

[0036]

[0037] Table 2

[0038] The total head performance curves of the four-stage axial flow pump in the comparative example and the double-layer booster impeller axial flow pump in this embodiment are compared with the four-stage axial flow pump in the comparative example. Figure 6 As shown, the total axial force curves of the double-layer booster impeller axial flow pump in this embodiment and the four-stage axial flow pump in the comparative example are compared. Figure 7As shown in the figure. From the axial force comparison curve, it can be seen that the axial force obtained by the rated point simulation calculation is slightly higher than the designed axial force. Compared with the axial flow pump designed by the conventional design method, the axial force of the axial flow pump rotor designed by the low axial force hydraulic design method is relatively low in the range of 0.2 times the rated working condition (0.2Qopt, Qopt is the rated working condition flow) to 1.4 times the rated working condition (1.4Qopt). Under the rated working condition, the axial force of the axial flow pump designed by the low axial force design method is about 1 / 4 of that of the axial flow pump designed by the conventional design method. Under the working condition of 0.2Qopt, it is only 1 / 5 of the axial force of the axial flow pump designed by the conventional design method.

[0039] In summary, it can be seen that after adopting the axial flow impeller design method in this embodiment and applying it to a multi-stage axial flow pump, the axial flow impeller in this embodiment receives lower axial force and runs more smoothly. In addition, among axial flow pumps of the same level, the axial length is smaller, the head is similar, and it is easier to transport.

[0040] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the technical solution. Those skilled in the art should understand that those modifications or equivalent substitutions of the technical solution of the present invention that do not depart from the purpose and scope of the technical solution should be included in the scope of the claims of the present invention.

Claims

1. A double-layer supercharged axial flow impeller, comprising an impeller body, wherein the impeller body comprises an inner wheel column and a plurality of inner blades circumferentially arranged outside the inner wheel column, characterized in that: An outer wheel column connected to the outer end of the inner blade is arranged outside the inner blade, and a plurality of outer blades are arranged circumferentially outside the outer wheel column; the inner blades and the outer blades are both arc-shaped and face in opposite directions.

2. The double-layer pressurized axial flow impeller according to claim 1, characterized in that: The cross-sectional shapes of the inner blades and the outer blades are airfoil-shaped.

3. An axial flow pump rotor, comprising a rotating shaft and at least one axial flow impeller sleeved and fixed on the rotating shaft, characterized in that: The axial flow impeller is as described in claim 1 or 2, and the axial force of the axial flow pump rotor satisfies the following formula: iF Z1 +G=iF Z2 +F T +F F ; In the formula, i represents the number of impeller bodies, F Z1 is the reaction force of the fluid on the inner blades, F Z2 is the reaction of the fluid on the outer blades, F T F is the pressure difference force on the inner wheel column shaft end, F is the buoyancy of the impeller body, and G is the deadweight of the axial flow pump rotor.

4. The axial flow pump rotor according to claim 3, characterized in that: Where k is the axial force coefficient of the impeller body, and ρ is the fluid density in kg / m 3 ; H2 is the lift of the outer blades, in m; g is the acceleration of gravity, D2 is the diameter of the circle formed by the outer ends of the outer blades, in m; d h2 is the diameter of the outer wheel column, in m; Where H1 is the lift of the inner blades, in m; D1 is the diameter of the circle formed by the outer ends of the inner blades, in m; d h1 is the diameter of the inner wheel column, in m; F T ={iρg(H1+H2)-p0}πd0 2 / 4, where d0 is the inner diameter of the inner wheel column, and p0 is the absolute pressure at the end of the shaft in the atmospheric environment; F F =ρgV, where V is the volume of the axial flow pump rotor immersed in the liquid, in m 3 ; G = ρ0Vg, where ρ0 is the material density of the axial flow pump rotor, kg / m 3 .

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