阅读说明：本技术 一种抑制轴流泵叶顶泄漏涡的叶片结构 (Blade structure for inhibiting axial flow pump blade tip leakage vortex ) 是由 沈熙 张德胜 许彬 王飞 金永鑫 潘强 赵旭涛 于 2021-01-12 设计创作，主要内容包括：本发明公开了一种抑制轴流泵叶顶泄漏涡的叶片结构,包括叶轮轮毂和转轮室,所述叶轮轮毂上安装有叶片,所述叶片的叶顶和所述转轮室内壁面之间构成叶顶间隙,所述叶片上开设有若干个腔体结构,所述腔体结构的入口位于所述叶片的叶片压力面上,所述腔体结构的出口位于所述叶片的叶顶上,所述腔体结构内的液体离心射流流速v-(c)与所述叶顶间隙处的液体泄漏流速v-(l)满足v-(c)=v-(l)/sinα；其中α为所述腔体结构内的液体离心射流出口方向与所述叶顶间隙处的液体泄漏流流动方向之间的夹角。本发明能有效干涉轴流泵叶顶泄漏流,抑制叶顶泄漏涡的产生,从而减弱叶顶泄漏涡诱导空化对轴流泵机组运行效率和稳定性的影响。(The invention discloses a blade structure for inhibiting axial flow pump blade tip leakage vortex, which comprises an impeller hub and a runner chamber, wherein a blade is arranged on the impeller hub, a blade tip gap is formed between the blade tip of the blade and the inner wall surface of the runner chamber, a plurality of cavity structures are arranged on the blade, the inlet of each cavity structure is positioned on the blade pressure surface of the blade, the outlet of each cavity structure is positioned on the blade tip of the blade, the flow velocity of liquid centrifugal jet flow in each cavity structure is v c Liquid leakage flow rate at clearance with the tip v l Satisfy the requirement of v c = v l A/sin alpha; wherein alpha is an included angle between the direction of a liquid centrifugal jet flow outlet in the cavity structure and the flowing direction of a liquid leakage flow at the blade top gap. The invention can effectively interfere the axial flow pump blade top leakage flow and inhibit the generation of blade top leakage vortex, thereby weakening the blade top leakage vortexThe influence of induced cavitation on the operating efficiency and stability of the axial flow pump unit.)

1. The utility model provides an restrain axial-flow pump blade top and leak blade structure of vortex, includes impeller wheel hub (1) and runner room (6), install the blade on impeller wheel hub (1), the blade top (10) of blade with constitute blade top clearance (2) between runner room (6) internal face, a plurality of cavity structures have been seted up on the blade, cavity structures's entry is located on the blade pressure surface (9) of blade, cavity structures's export is located on the blade top (10) of blade, the liquid centrifugation efflux velocity of flow in the cavity structuresv _c The liquid leakage flow rate at the clearance (2) with the blade topv _l Satisfy the requirement ofv _c =v _l /sinα(ii) a Wherein α is an included angle between the liquid centrifugal jet flow outlet direction in the cavity structure and the liquid leakage flow flowing direction at the blade tip gap 2.

2. The blade structure for suppressing axial flow pump blade tip leakage vortex according to claim 1, wherein the cavity structure is a circular hole cavity, the circular hole cavity penetrates from a pressure surface at a blade root to the blade tip, and a bending direction of the circular hole cavity inside the blade is the same as a bending direction of the blade.

3. The vane structure for suppressing axial flow pump vane tip leakage vortex according to claim 2, wherein the number of the cavity structures is 5.

4. The vane structure of claim 3, wherein each of said cavity structures is uniformly arranged within said vane.

Technical Field

The invention discloses a blade structure for inhibiting axial flow pump blade tip leakage vortex, and belongs to the technical field of fluid machinery.

Background

The axial flow pump has the characteristics of high flow, low lift, high efficiency and the like, and is widely applied to the fields of large-scale water transfer engineering, nuclear power engineering, ship water jet propulsion and the like. The axial flow pump has a blade top gap inevitably existing between a wheel rim and a runner chamber due to the structural characteristics, and leakage flow is generated in the blade top gap due to the pressure difference driving of a pressure surface and a suction surface of a blade. The blade tip leakage flow is mixed with the main flow and sucked under the action of shearing force to form a blade tip leakage vortex, the blade tip leakage vortex interferes with a flow field of a blade tip area and induces complex cavitation structures such as cavitation in a gap, jet shear layer cavitation, blade tip leakage vortex cavitation and the like, the flow stability in the pump is damaged, and abnormal vibration and noise are generated. Particularly, under the working condition of small flow, the cavitation vortex band and the surface flaky cavitation interfere to form vertical cavitation vortex to block the flow channel, so that the efficiency of the unit is reduced. At present, common axial flow pump blades are traditional modeling blades without structural change, and the blade tip leakage vortex and induced cavitation are difficult to avoid during operation, so that the safe and stable operation of a unit is influenced. Through retrieval, the published patents 'an axial flow pump impeller for a chemical reactor' (application number: 2012105867470) and 'an anti-cavitation axial flow pump impeller design method' (application number: 2015109088370) are both traditional blade structures, and the generation of blade tip leakage vortex and the influence on the pump performance are not fully considered; the patent of "a vane structure for attenuating leakage flow and leakage vortex of an axial flow pump tip" (application No. 201310412030.9) has been disclosed, which reduces the amount of leakage by changing the shape of the tip into a zigzag structure, which causes great difficulty in the process of manufacturing and assembling, and does not fundamentally suppress the tip leakage. The patent "axial flow pump impeller with improved cavitation erosion resistance" (application No. 201710294309X) has been disclosed to improve cavitation erosion resistance by reducing tip clearances and reducing tip vortices. The method has higher requirement on the processing precision, and greatly increases the processing difficulty and cost.

Disclosure of Invention

The invention aims to provide a blade structure for inhibiting axial flow pump blade top leakage vortex, which can weaken leakage jet flow in an axial flow pump blade top gap, inhibit blade top cavitation damage, prolong the service life of an axial flow pump blade and improve the operation efficiency and stability of an axial flow pump unit.

In order to realize the purpose, the invention adopts the technical scheme that: the utility model provides a restrain blade structure of axial-flow pump blade top leakage vortex, includes impeller wheel hub and runner room, the last blade of installing of impeller wheel hub, the blade top of blade with constitute the blade top clearance between the runner room internal face, a plurality of cavity structures have been seted up on the blade, cavity structures's entry is located on the blade pressure surface of blade, cavity structures's export is located on the blade top of blade, the liquid centrifugation efflux velocity of flow in the cavity structuresv _c Liquid leakage flow rate at clearance with the tipv _l Satisfy the requirement ofv _c =v _l A/sin alpha; wherein alpha is an included angle between the direction of a liquid centrifugal jet flow outlet in the cavity structure and the flowing direction of a liquid leakage flow at the blade top gap.

In the above scheme, the cavity structure is a circular hole cavity, the circular hole cavity penetrates from the pressure surface at the blade root to the blade top, and the bending direction of the circular hole cavity in the blade is the same as the bending direction of the blade.

In the above scheme, the number of the cavity structures is 5.

In the above scheme, each cavity structure is uniformly arranged inside the blade.

In the above scheme, the rear of the impeller hub is also provided with a guide vane and a support plate.

The beneficial effect of this patent: according to the invention, the cavity structure is arranged on the pressure surface of the blade and penetrates to the blade top surface, and the blade top jet flow is formed at the outlet of the cavity structure by using the centrifugal force of the medium, so that the formation of the leakage vortex of the blade top of the axial flow pump is inhibited, and the operation efficiency and the stability of the pump are improved.

Drawings

Fig. 1 is an axial cross-section overall structure schematic diagram of an axial flow pump.

FIG. 2 is an axial sectional view of the mechanism of axial flow pump blade tip leakage vortex formation.

FIG. 3 is a schematic view of a blade tip leakage vortex state of a common axial-flow pump blade.

FIG. 4 is a schematic view of the overall structure of the radial hole of the axial flow pump blade.

FIG. 5 is a schematic view of a radial perforated axial flow pump centrifugal jet flow disturbing blade tip leakage flow.

FIG. 6 is a schematic view of the distribution of openings on the pressure side of a blade.

Fig. 7 is a sectional view a-a of fig. 6.

FIG. 8 is a schematic view of the distribution of openings at the blade tip of a blade.

In the figure, 1 is an impeller hub, 2 is a blade top gap, 3 is a guide blade, 4 is a support plate, 5 is a transmission shaft, 6 is a runner chamber, 7 is an outlet bent pipe, 9 is a blade pressure surface, 10 is a blade top, and 11 is a blade suction surface.

Detailed Description

The invention is described in further detail below with reference to the figures and the specific embodiments, but the scope of the invention should not be limited thereby.

Referring to fig. 1, when the axial-flow pump operates, a fluid medium flows through the impeller, the guide vane 3 and the support plate 4 from left to right in sequence and flows out through the outlet elbow 7; the impeller is used as a core component of the axial flow pump, and the hydraulic performance of the pump is determined; the impeller is driven by the transmission shaft 5 to rotate, and the fluid medium is stressed on the pressure surface 9 of the blade to increase kinetic energy and flow to the guide vane 3 at a certain outlet angle; a tip clearance 2 exists between the impeller chamber 6 and the impeller tip 10. The mechanism of formation of the axial flow pump tip leakage vortex is shown in fig. 2, and under the driving of the pressure difference between the pressure surface and the suction surface, the tip leakage flow moves from the pressure surface to the suction surface through the tip clearance, and under the entrainment action with the main flow, the tip leakage vortex is formed as shown in fig. 3.

In the technical scheme of the embodiment, as shown in fig. 4, a blade is installed on an impeller hub 1, a blade tip gap 2 is formed between a blade tip 10 of the blade and the inner wall surface of a runner chamber 6, 5 circular hole cavities are formed in the blade, each circular hole cavity penetrates through the blade tip from a pressure surface at the blade root, and the circular hole cavities are bent inside the bladeThe direction is the same as the bending direction of the blade. The inlet of each circular hole cavity is positioned on the pressure surface 9 of the blade, the outlet of each circular hole cavity is positioned on the blade top 10 of the blade, and the centrifugal jet flow velocity of the liquid in the cavity structurev _c The liquid leakage flow rate at the gap 2 with the blade topv _l Satisfy the requirement ofv _c =v _l A/sin alpha; wherein α is an included angle between the liquid centrifugal jet flow outlet direction in the cavity structure and the liquid leakage flow flowing direction at the blade tip gap 2. The fluid medium in the circular hole cavity forms radial centrifugal jet flow at the blade top under the action of centrifugal force to interfere the leakage flow of the blade top, so that the generation of leakage vortex and cavitation of the blade top is inhibited.

According to the invention, the blade structure of the axial flow pump is innovated to interfere the leakage flow at the blade top, and when the axial flow pump operates, the cavity of the circular hole is filled with a medium; referring to the attached drawing 5, when the impeller rotates at a certain rotation speed, the medium in the circular hole forms a centrifugal jet under the action of centrifugal force, and impacts the blade top leakage flow at a certain angle alpha, so that the effect of inhibiting the formation of blade top leakage vortex is achieved, and the blade top leakage flow and the centrifugal jet are synthesized into a jet flow perpendicular to the blade top. The axial flow pump impeller rotates to enable the fluid medium to generate centrifugal force, the operation efficiency of the unit is not obviously affected, and the leakage vortex and cavitation of the blade top can be inhibited.