WO2019022691A1

WO2019022691A1 - Centrifugal double intake fan impeller

Info

Publication number: WO2019022691A1
Application number: PCT/UA2017/000112
Authority: WO
Inventors: Андрей Иванович ПАНФИЛОВ; Владимир Григорьевич ПРОСНИЦКИЙ
Original assignee: Андрей Иванович ПАНФИЛОВ
Priority date: 2017-07-28
Filing date: 2017-12-04
Publication date: 2019-01-31
Also published as: RU2746769C1; UA119693C2

Abstract

An impeller of a centrifugal double intake fan. Use: the invention relates to the field of mechanical engineering and can be used in impellers of centrifugal double intake fans intended for use in dust-laden environments. Aim: to improve the impeller of a centrifugal double intake fan. Essence: a centrifugal double intake fan impeller comprises blades, cover disks, reinforcing rings, and a toothed centre disk with recesses between the blades, wherein one side of a recess, the shape of which is complementary to the shape of the working surface of a blade, meets on the arc of a circle with a free side which is shaped like the leg of a parabola. The arc of the circle on which the sides of a recess meet has a radius r = 0.0088 D2, and is tangential to a circle DB, which is concentric with a circle D2, and to the side with a shape complementary to the shape of the working surface of a blade, where D2 is the outside diameter of the impeller, D0 is the diameter of the position of the leading edge of a blade, concentric with D2, DB is the inside diameter of a recess taken as (1.04 – 1.16) D0, and the blade solidity l/t CP is taken as equal to (1.4 – 2.5), where l is the length of a blade, tCP is the distance between blades on a mean diameter Dcp = (D2+D0)/2. The peripheral part of the free side of a recess between blades, on the outside diameter of the impeller D2, is at a distance α = 0.007 D2 from the trailing side of the blade. Technical result: an increase in the structural strength and durability of the impeller.

Description

Impeller of centrifugal double-sided fan

The invention relates to the field of engineering and can be used in the impellers of centrifugal fans designed to work in dusty environments.

Known centrifugal supercharger impeller for US patent N ° 2287853 from 06/30/1942, containing blades, covering disks, stiffening rings, toothed central disk with interscapular depressions, one side of which, made in the form of the response form of the working surface of the blade, is paired with another free side along the radius of the arc of a circle.

Unlike the claimed utility model, in the above patent, the design of the central disk of a double-suction fan is made with a V-shaped notch. According to the patent, the outer part of the central disk is removed in the impeller of the fan to the inlet edge of the blade, which is adjacent to the front surface of the blade. The base of the V-shaped notch at the inlet edge of the blade is described along the radius at which the sufficient strength of the central disk is not ensured, especially in fan designs with backward-curved blades. And this is the majority of smoke exhausters and superchargers, which are subject to intensive gas-abrasive wear of central discs, which limits the durability of these machines.

Also known is a centrifugal supercharger impeller according to the US patent Ν ° 2653755 dated 09/29/1953, containing blades, covering disks, stiffening rings, a toothed central disk with interscapular depressions, one side of which, in the form of a response form of the working surface of the blade, is paired with another free side along the radius of the arc of a circle. TU 2017/000112

In contrast to the claimed invention, in the base of the V-shaped cuts there are made the slots extending inside the central disk, the inner edges of which are made along the radii for installing the lining elements protecting the input edge of the blades from wear. However, this technical solution significantly reduces the strength of the central disk due to an increase in loads at the base of the tooth and a large concentration of stresses in a small-sized radius. For fans with backward curved blades, this technical solution is not applicable due to unacceptably high voltages occurring in the central disks.

Also known impeller centrifugal double-sided fan along.with. USSR J4 ° 534586, M. KL. F04D 29/28, publ. 05. 1 1 .76, 6ΚΜ.Ν ° 41, containing blades, covering disks, stiffening rings, toothed central disk with interscapular depressions, one side of which, made in the form of a response form of the working surface of the blade, is conjugated to the other free side along the arc radius circle.

In contrast to the claimed invention, in the fan, the depressions in the central disk are radial. The conjugation of the sides forming the notches in the central disk is made along two radii, depending on the size of the notches step t in internal diameter and equal to r = (0.04-0, 1 1) / and R = (0, 12-0, 13) /, i.e. the sides of the notch are outlined with an ellipse, the smaller arc of which is mated with the vane, and the larger one - with the opposite side of the notch on its inner diameter.

However, in the design of the impeller, there is a decrease in the structural strength of the central disks.

The closest analogue to the claimed invention on the totality of features and the achieved technical result is the impeller of the centrifugal double-sided fan _ ac USSR 0361 12, IPC F04D 29/28, dated 26.03.80, containing blades, covering disks, stiffening rings, a toothed central disk with interscapular depressions, one side of which is made in the form of the response form of the working surface of the blade, is coupled with another free side , made in the form of a branch of a parabola.

In contrast to the claimed invention in the fan, the side of the depression of the central disk, on the side of the opposite blade, is made in a parabola. In this case, there is an uncertainty in the location of the parabola in the depression, in particular, its focus on a straight line passing through the input edge of the blade and its center of curvature, and the axis of the parabola, which caused the same uncertainty and error of the actual configuration parameters of the interscapular depression and the ratios of the design parameters of the working wheels.

As a result, this invention has not achieved a reduction in the effects of alternating loads on a toothed central disk and an optimal reduction in the stress concentration in the cavity of the disk.

For example, when passing a straight line with a parabola focus lying on it, i.e. the Y-axis of the curve through the front edge of the blade takes the bend - the angle due to the non-smooth conjugation of the curve, the response profile of the blade with a branch of a parabola (see Fig. 3, A.S. USSR - Ν 10361 12). As indicated in the description of the invention, the specified author’s certificate in this place forms a zone of significant complex voltage concentrator. As a result, in such a structure, a zone sensitive to vibrations of the structure arises, which leads to the occurrence of cracks in the central disk web directly in front of the entrance edge of the blade. Thus, the execution of the side of the depression opposite the blade on a smoothly varying continuous curve provides a smooth but insufficient reduction of the stresses in the danger zone. The high level of stress at the base of the depression is due to the effect of stress concentration, which

s depends on various structural elements determined by the aerodynamic design and design of the impeller: the number of blades, exit angle, entrance diameter, twist radius at the base of the trough. Other things being equal, the determining factor is not only the magnitude of the junction of the sides of the depression, but also the configuration of the entire depression from the side of the reciprocal front surface of the blade to the upper edge of the notch in the central disk on the outer diameter £ ₂ . The smoother the curvature of the side of the depression opposite the working surface of the blade, the more fully the material of the remaining part of the tooth is used, the lower the stress concentration in the cavity and the lower the load in the central disk. Therefore, the identification and establishment of the optimal configuration of the interscapular depression and the ratios of the design parameters of the impeller remains relevant.

The invention is based on the task to improve the impeller of a centrifugal double-sided fan, by optimizing the configuration of the interscapular cavity and ratios of the design parameters of the working wheel, reduce the effect of alternating loads on the toothed central disk and the stress concentration in the cavity of the disk, and thereby increase the structural strength and durability impeller.

The problem is solved by the fact that in the impeller of a centrifugal double-sided fan containing blades, covering disks, stiffening rings, a jagged central disk with interscapular depressions, one side of which, made in the form of the response form of the working surface of the blade, is paired with another free side, made in the shape of a branch parabola, circular arc, according to the invention, the arc conjugation circumferential sides depressions formed radius r = 0.0088 tangent to the circle d _H, concentric circle d ₂ and to the side vypol ennoy shape the reciprocal shape of the blade surface, where D ₂ is the outer diameter of the impeller, D _Q is the diameter of the location of the input edge of the blade, concentric D ₂ , D _H is the inner diameter of the cavity taken (1, 04 - 1, 16) £> ₀ , the thickness of the blade grille l / t _a> taken equal to (1.4 - 2.5), where / is the length of the blade, t _cl , ~ distance between the blades on the average diameter Dcp = ^ _> ^P P ^{And this is the} peripheral part of the free side of the interscapular cavity, on the outside the impeller diameter D _{2 is} made at a distance = 0.007 D ₂ , from the back of the blade, the parabola branch is made according to below n The values of X and Y coordinates given in the table are taken in relation to D ₂ ,

the axis of symmetry Y of the parabola branch passes through the center of the arc of a circle of conjugation of radius r, and the vertex of the parabola is conjugated with this arc of a circle at its intersection with the said axis of symmetry.

Due to the fact that the arc of the circumference of the sides of the depression is made with a radius g of 0.0088 D ₂ , tangent to the circumference D _H , the concentric circumference D ₂ , and to the side of the working surface of the blade, which is shaped in response to the shape, where D ₂ is the outer diameter of the impeller , D _n - diameter of the location of the entrance edge of the blade concentric D ₂ , D _H - inner diameter of the cavity taken (1, 04 - 1, 16) D ₀ , the thickness of the blade grille l / t _l , taken to be (1, 4 - 2.5 ), where / - the length of the blade, t _cp - the distance between the blades on the average diameter Dcp = ^~ ^ ^D ° ^ wherein, the peripheral Part free hand interscapular depressions on the outer diameter of the impeller D _{2 is} made at a distance of a = 0.007 D ₂ , from the back side of the blade, the parabola branch is made according to the X and Υ coordinates values given below in the table in relation to D ₂ ; optimization of the configuration of the inter-blade depression and the ratio of the design parameters of the impeller is achieved. This allowed smoothly, without kinking, to connect the reciprocal side in the shape of the working blade with the opposite side of the depression. Also, place the base of the cavity on the diameter D _{: i} = (1, 04. 1, 16), and change the thickness of the blade grid l / ( _rr from 1, 4 to 2.5, which allowed the blade to be inserted into the central disk by the minimum required value Due to this, a smooth change in stiffness from the blade grating to the central part of the carrier disk has been achieved, as well as a significant reduction in loads on the elements of the impeller of the fan, and as a result, an increase in its structural strength and durability.

The invention is illustrated by drawings, where: figure 1 - shows a General view of the impeller of a centrifugal double-sided fan;

figure 2 - General view of the impeller of a centrifugal double-sided fan in the section along the axis;

fig.Z - a fragment of a gear central disk with interscapular depressions.

The impeller of a centrifugal double-sided fan contains blades 1, covering disks 2, stiffness rings 3, toothed central disk 4 with interscapular depressions 5, one side 6 of which is shaped in response to the shape of the working surface of blade 1 and is associated with the other, free side 7 made in form branches of a parabola. The free side 7 of the said interscapular cavity 5 of the central disk 4 is associated with side 6 of the blade surface 1 that responds in shape along the arc of a circle 8. Arc

b the circumference of the sides 8 of the depression 5 is made with a radius, g = 0.0088 D, tangent to the circle D _R , the concentric circle, and to the side 6 of the working surface of the blade 1, which is in response to the shape, where is the external diameter of the impeller, is the diameter of the location the input edge of the scapula 1 is concentric. The inner diameter of the depression (D) is taken within (1, 04 - 1, 16) D. The density of the blade grating l / t _{p is} taken equal (1, 4 - 2.5), where / is the blade length t _n , is the distance between the blades on the average diameter Dcp = ^ ~ ^ -. The peripheral part of the free side 7 of the interscapular depression 5, on the outer diameter of the impeller D _{2 is} made at a distance of a = 0.007 d, from the back side of the blade 1. The parabola branch of the free side 7 of the depression 5 is made according to the X and Y coordinates taken in the following ratio to D .

The axis of symmetry Y of the parabola branch passes through the center of an arc of a circle 8 of radius r, and the top of the parabola is connected to this arc of a circle 8 at the point 9 of its intersection with the said axis of symmetry.

MDR-30000 and HP-32500SW centrifugal fans were tested in industrial conditions at the Krivoy Rog northern mining and processing plant. As a result of the test, the following was established. The maximum voltage in the depression of the central disk in the MDR-30000 centrifugal fan made according to the invention in a. USSR 10361 12 is about _max = 576.4 MPa. Maximum voltage at the trough of the central disk in HP-32500SW centrifugal fan, made in accordance with the claimed utility model is a _max = 393.49 MPa.

Claims

Claim

1. The impeller of a centrifugal double-sided fan containing blades, covering disks, stiffening rings, toothed central disk with interscapular depressions, one side of which, made in the form of a response form of the working surface of the blade, is conjugated with another free side, made in the shape of a branch of a parabola, along an arc circumference, characterized in that the arc of the circumference of the sides of the depression is made with a radius g of 0.0088 D, tangent to circumference D, concentric circumference d and to the side made in the form of a response oh form the working surface of the blade, where D is the outer diameter of the impeller, D is the diameter of the location of the entrance edge of the blade concentric d, D _H is the inner diameter of the cavity taken within (1, 04 - 1, 16) D, the thickness of the blade grille l / t _a , taken equal to (1, 4 - 2.5), where / is the length of the blade, d, is the distance between the blades on the average diameter

Dcp = _> ^P ^And this peripheral part of the free side of the interscapular cavity, on the outer diameter of the impeller D is made at a distance of a = 0.007, from the back side of the blade, the parabola branch is made according to the values of X and Y coordinates given below in the table in relation to D ,

The axis of symmetry Y of the branch of the parabola passes through the center of an arc of a circle of radius r, and the vertex of the parabola is conjugated with this arc of a circle at its intersection with the said axis of symmetry.