Closed-type vortex impeller with enhanced anti-cavitation properties for a closed-vortex pump

Abstract

This utility model relates to pump engineering, specifically closed-vortex pumps, and is designed to improve the anti-cavitation properties of closed-type vortex impellers. The device comprises a hub and a disk with straight radial blades whose rear end edges are rounded, and the blades have a backing along the periphery of the impeller. The technical result is improved anti-cavitation properties of a closed-type vortex impeller when the pump operates at speeds exceeding its nominal value.

Description

[0001] The utility model relates to the field of pump engineering, in particular, to closed-vortex pumps, and is intended to improve the anti-cavitation properties of closed-type vortex wheels.

[0002] A closed-vortex pump is a vortex pump in which the liquid is supplied directly to a stationary annular channel. The annular channel in the pump casing is connected to the suction and discharge ports via a bridge and is located along the circumference described by the impeller blades. Moreover, along the impeller ends, the channel has sufficient radial clearances along the blades' length, while along the impeller's periphery, the clearances are minimal.

[0003] The closed-type impeller (see the article "Operating Diagram, General Information on Vortex Pumps" at URL: https: / / www.nasos-italy.ru / stat / vihrevye_nasosy) has short, straight, radial blades with a transverse baffle. In a closed-type impeller pump, the liquid, entering from the suction port directly into the annular channel, moves through the channel much more slowly than the rotating impeller blades. Particles of the liquid, accelerated by the impeller blades, also enter the annular channel and from the channel, return to the impeller blades. The resulting friction causes intense mixing of the liquid and vortex formation, ensuring multiple energy transfer from the blades to the liquid and flow movement into the discharge port.

[0004] The disadvantage of a closed-vortex pump with a fixed annular channel in terms of the development of pressure cavitation on the blades of a closed-type vortex wheel is that intense vortex formation due to high circumferential and relative flow velocities contributes to the separation of liquid from the surface of the blade, and at the point of separation, a sharp increase in pressure occurs.

[0005] Flow separation from the surfaces of the vortex wheel blades occurs, among other things, due to a sharp increase in local flow pressure in the peripheral gaps between the blades of the impeller and the pump channel due to the passage of part of the liquid medium through the gaps at a very high speed.

[0006] It is known that backed outlet sections (bevel on the rear side) of centrifugal impeller blades reduce the unevenness of flow velocities at the outlet from the interblade space. This, by changing the nature of the flow around the blade, allows for a smoother flow exit, thereby slightly reducing the absolute flow velocity and avoiding a sharp drop in pressure in the interblade space and at the impeller outlet (Author's Certificate No. 1059272 published 07.12.1983). At the same time, backing allows for a small (approximately 5%) increase in pump pressure.

[0007] A free-vortex pump impeller is known (Author's certificate No. 1576733 published 07 / 07 / 1990), containing a hub and a disk with radial flat blades, in which the edges of the blades are rounded on the working side of the blades from the outer radius of the hub R1 to the radius , and on the back side from the radius R0 to the outer radius R2 of the disk.

[0008] A disadvantage of this impeller is that it cannot be used in closed-vortex pumps. The rounded end edge of the blade surface is a useful design feature, as it causes flow separation from the blade's back edge due to a sudden change in direction, disrupting laminar flow. Furthermore, as the fluid flows around the sharp edge of the blade surface, the flow may become unstable and separate from the blade surface, creating a vortex zone in the interblade space.

[0009] The technical problem that the utility model is aimed at solving is the creation of a vortex impeller for a closed-vortex pump.

[0010] The technical result is an increase in the anti-cavitation properties of a closed-type vortex impeller when the pump is operating at modes exceeding the nominal one.

[0011] The technical result is achieved in that the closed-type vortex impeller for a closed-vortex pump contains a hub and a disk with straight radial blades.

[0012] The peculiarity is that the blades have rounded end edges on the back side, and along the periphery of the wheel on the back side of the blades there is a backing.

[0013] The essence of the utility model is explained by drawings, where

[0014] Fig. 1 shows a closed type vortex wheel, front view,

[0015] Fig. 2 shows a closed type vortex wheel, side view,

[0016] Fig. 3 shows the backing of the peripheral edges of the blades of a closed-type vortex wheel,

[0017] Fig. 4 shows the rounding of the end edge of the rear surface of the blade of a closed-type vortex wheel.

[0018] The closed type vortex impeller comprises a hub 1 and a disk 2 with straight radial blades 3. The edges 4 of the blades 3 are rounded on the back side 6.

[0019] The proposed closed type vortex wheel works as follows.

[0020] The liquid medium, entering the pump annular channel under pressure from the suction port, moves through the channel much more slowly than the rotating impeller blades. Liquid particles accelerated by the impeller blades also enter the annular channel and from the channel, return to the impeller blades. The resulting friction causes intensive mixing of the liquid medium and vortex formation, ensuring multiple energy transfer from the blades to the liquid medium and flow movement into the discharge port. At the same time, the rounding of the end edges 4 of the blades 3 on the back side 6 reduces the flow of liquid medium from the working side 5 to the back side 6, ensures flow separation from the edges 4 of the working side 5 of the blades 3 and additional vortex formation, promoting entrainment of the liquid medium in the circulation flow in the channel and reducing the likelihood of the formation of low-pressure zones.The backing of the peripheral edge of the blades 3 from the rear side 6 allows for a reduction in the absolute velocity of a portion of the liquid medium when passing through small gaps between the surfaces of the impeller blades and the surface of the pump channel, which also reduces the likelihood of the formation of low-pressure zones.

Claims

A closed-type vortex impeller for a closed-vortex pump, comprising a hub, a disk with straight radial blades, characterized in that the blades have rounded end edges on the rear side, and along the periphery of the wheel, the blades on the rear side have a backing.

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