RU2639241C1 - Duct fan - Google Patents

Abstract

FIELD: ventilation.

SUBSTANCE: duct fan comprises of a housing 1 with a cylindrical section, a radial impeller 4 formed by a cover 5 and main 6 disk and a backward curved blade 7 between them, the diameter D₂ of which is equal to the diameter of the junction of the blades 7 with the main disk 6, a drive 10 with a fairing 11 including a cylindrical section. The trailing edge 8 of the blades 7 comprises of a section, adjacent to the main disk 6, with a length of 0.32…0.45 of the width b₂ of the blade 7 with a constant distance to the axis of rotation 9 and a section with an increasing distance from the axis of rotation 9 to the trailing edge 8 when approaching the cover disk 5. There are blades of a straightener 3 between the cylindrical sections of the housing 1 and the fairing 11. The diameter of the main disk 6 is (1.01…1.03) D₂, of the cover plate 5 - (1.05…1.15) D₂, the width b₂ of the blade 7 is (0.20…0.48) D₂.

EFFECT: ensuring high values of full efficiency at high values of the capacity factor.

11 cl, 10 dwg

Description

The invention relates to the field of fan technology, namely to channel or roof fans with a radial impeller having vanes bent backward.

In the prior art, channel fans with a radial impeller are known, in which the casing is made with a cylindrical section.

So, from the description of the invention to the patent of the Russian Federation No. 2051295, IPC F04D 17/08, F04D 29/66, publication date 12/27/1995, [1], a direct-flow fan is known comprising a housing, a radial impeller, an axisymmetric input manifold, a radome around the radial drive the impeller and the straightening apparatus, the housing is made with a cylindrical section, the radial impeller is formed by the main and cover disks with the vanes bent backward between the disks, while the maximum diameter of the blades mating with SIC disk axisymmetric inlet manifold is made with a curvilinear generatrix is located at the inlet of the radial impeller coaxially with the radial impeller is kinematically connected with a drive mounted in the radome equipped with a cylindrical portion and the front wall. A feature of the invention [1] is the small width of the radial impeller, comprising 0.03 ... 0.045 of the diameter of the radial impeller, and the absence of a blade rectifier. This does not allow to achieve high values of the coefficient of performance ϕ and efficiency (efficiency) η, which is a disadvantage of the fan known from the invention [1].

Similar schemes are considered in publications: “Research of radial-axial rectifying apparatuses”, “Industrial aerodynamics”, Collection No. 6, BNI, 1955, [2], “Direct-flow centrifugal fans”, I.V. Brusilovsky, Industrial Aerodynamics, Collection No. 9, BNI, 1957, [3]. In these works, direct-flow radial fans and methods for profiling a straightening blade apparatus located between a cylindrical body and an internal fairing are considered. The maximum efficiency achieved in the fan circuits presented in articles [2, 3] reaches η = 0.68-0.76 with small performance factors ϕ = 0.1-0.12. Low efficiency at high values of the performance coefficient ϕ> 0.12 is a disadvantage of fan circuits presented in articles [2, 3].

While in Russia direct-flow fan circuits are not widespread and you can find only their simplified, small-sized options, abroad, for example in the USA, large-sized fans are mass-produced.

Companies such as TwinCity, LorenCook, S&P and others, mass-produce ramjet fans with a cylindrical body of large sizes. There are also a large number of inventions for various variants of direct-flow fans with a radial impeller in a cylindrical housing, presented, for example, in the descriptions of inventions in US patent No. 3069071; No. 3102679; No. 3412929; No. 3584968; No. 3650633; No. 4092088; No. 4828456; No. 5209639; No. 5810557. The disadvantage of the technical solutions presented in these inventions is the efficiency of the channel fans, not exceeding a value of 73%: η≤0.73.

From the description of the invention according to the patent of the Russian Federation No. 2289728, IPC F04D 17/16, publication date 12/20/2006, [4], a channel radial fan is known comprising a housing, a radial impeller, an axisymmetric input manifold, a radial impeller drive, a cowl drive and a straightening apparatus, the housing is made with a cylindrical section, the radial impeller is formed by the main and cover disks with the vanes bent backward between the disks, the axisymmetric inlet manifold is made with a curved generatrix, located on the input de in the radial impeller coaxial with it with the formation of a confuser gap between the surfaces of the inlet manifold and the cover disk of the radial impeller, the radial impeller is kinematically connected to the drive installed in the fairing, having a cylindrical section and a front wall, the straightening device contains blades mounted in the channel between the cylindrical sections of the fairing and the housing. The disadvantage of the invention [4], taken as the closest analogue of the invention, is the lower performance and pressure ratios.

The technical task to be solved is to increase the total efficiency of the duct fan at high performance factors.

The technical result is to provide high values of full efficiency at high values of the coefficient of performance.

Disclosure of the invention.

The duct fan, as well as the closest analogue [4], contains a housing, a radial impeller, an axisymmetric inlet manifold, a radial impeller drive, a drive fairing and a straightening apparatus, the casing is made with a cylindrical section, the radial impeller is formed by the main and cover disks with placed between the disks, backward-curved blades, an axisymmetric inlet manifold is made with a curvilinear generatrix, located at the entrance to the radial impeller and coaxial with it to form a confuser about the gap between the surfaces of the inlet manifold and the cover disk of the radial impeller, the radial impeller is kinematically connected to the drive, the cowl of the drive is made with a cylindrical section and with the front wall, the straightening device contains blades, is installed in the channel between the cylindrical sections of the cowl and the housing, but in contrast from the closest analogue [4] the width of the blade equal to the distance between the main and cover discs on the diameter of the radial impeller is 0.2 ... 0.5 of the diameter of the radial the working wheel, the output edge of the blades of the radial impeller contains at least two sections, characterized by a change in the distance to the axis of rotation of the radial impeller in each of the sections, while in the first section adjacent to the main disk, which is 0.32 ... 0 45 the width of the blade of the radial impeller, the distance from the axis of rotation to the outlet edge of the blade remains constant, and in the second section, the distance from the axis of rotation to the outlet edge gradually increases as it approaches the cover the disk up to the radius of the cover disk, while the diameter of the main disk is 1.01 ... 1.03 of the diameter of the radial impeller, the diameter of the cover of the disk is 1.05 ... 1.15 of the diameter of the radial impeller, the diameter of the cylindrical section of the fan casing does not exceed 1 , 65 of the diameter of the radial impeller, and the diameter of the cylindrical portion of the radome of the drive radial impeller is at least 1.1 of the diameter of the radial impeller, while the diameter of the radial impeller is the maximum diameter I have blades with a main disk.

The channel fan is characterized in that the portion of the cover disk of the radial impeller from the diameter of the radial impeller to the outer diameter of the cover disk is made flat.

The channel fan is characterized by the fact that the plot of the casing disk of the radial impeller within the diameter of the radial impeller is made conical in shape with angles forming 50 ... 70 degrees relative to the axis of rotation of the radial impeller.

The duct fan is characterized in that at least one hole is made in the front wall of the cylindrical radome of the drive of the radial impeller.

The duct fan is characterized in that the radome impeller drive fairing comprises a conical section adjacent to the cylindrical section, tapering to the fan outlet, ending with a rear end.

The channel fan is characterized in that the rear end of the fairing is equipped with a plug, and a pipe is installed between the housing and the fairing of the drive, which is pneumatically connected to the cavity formed by the fairing and exiting the exterior of the channel fan housing.

The duct fan is characterized by the fact that the blade of the rectifier is made along an arc of a circle without twist along the radius of the casing, has installation angles at the entrance of 25-45 degrees relative to the circumferential direction, installation angles at the outlet of 75-83 degrees relative to the circumferential direction, and the density of the blades of the rectifier is 0.9-1.2.

The channel fan is characterized in that the drive comprises an electric motor, on the shaft of which a radial impeller is installed.

The channel fan is characterized in that the drive comprises a bearing assembly connected by a shaft to the radial impeller, and the bearing assembly is kinematically connected to an electric motor mounted on the outer surface of the channel fan housing.

The channel fan is characterized in that a conical section adjoins the cylindrical section of the casing from the outlet side of the channel fan with an angle between the generatrix and the axis of rotation of the radial impeller within 25 ... 45 degrees.

The duct fan is characterized in that the cylindrical portion of the housing around the rectifier is sound-absorbing.

The presented features form the totality and are essential for solving the task and achieving the claimed technical result.

The invention is illustrated by drawings and graphs.

In FIG. 1 shows a duct fan in side view.

In FIG. 2 shows a section aa in FIG. one.

In FIG. 3 is a longitudinal section through a duct fan.

In FIG. 4 shows the extension B in FIG. 3.

In FIG. 5 is a longitudinal section through a duct fan with a cylindrical body.

In FIG. 6 shows a longitudinal section of a duct fan with cylindrical and conical sections of the housing and the cowl of the drive.

In FIG. 7 is a longitudinal sectional view of a duct fan with a pipe for cooling a drive motor located between cylindrical portions of the housing and the cowl of the drive.

In FIG. Figure 8 shows a longitudinal section of a duct fan with a drive cowl with cylindrical and conical sections and a pipe for cooling the electric motor.

In FIG. 9 is a longitudinal sectional view of a channel fan with a drive bearing assembly located in the fairing kinematically connected to an electric motor mounted outside the channel fan housing.

In FIG. 10 is a graph of the dependence of the pressure coefficient Ψ and coefficient of performance (efficiency) η on the coefficient of performance ϕ for the same radial impeller in a direct-flow cylindrical with a straightening device ("channel") and without a straightening device ("channel analog") channel housing fan, as well as in a spiral ("spiral") case.

Channel fan is arranged as follows.

The duct fan contains a housing 1 with a cylindrical section with a front manifold 2 (Fig. 1, 2, 3), in which are located the blades of the straightening apparatus 3, the radial impeller 4, formed by the cover 5 and the main 6 disks and the vanes 7 curved backward between the disks (Fig. 3, 4). Moreover, the diameter of the radial impeller D ₂ adopted the maximum diameter of the pair of blades 7 with the main disk 6 (Fig. 3). The output edge 8 of the blades 7 of the radial impeller 4 contains at least two sections characterized by a change in the distance to the axis of rotation 9 of the radial impeller 4 (Fig. 3): in the first section adjacent to the main disk 6, the distance from the axis of rotation 9 to the exit the edge 8 of the blade 7 is kept constant, and in the second section adjacent to the cover disk 5, the distance from the axis of rotation 9 to the output edge 8 gradually increases as we approach the cover disk 5 until it adjoins the outer contour of the cover disk 5. The diameter of the main disk 6 is 1.01 ... 1.03 of the diameter D _{2 of the} radial impeller 4, the diameter of the cover disk 5 is 1.05 ... 1.15 of the diameter D _{2 of the} radial impeller 4. The width b _{2 of the} blade 7 is equal to the distance between the main 6 and cover 5 discs on the diameter D _{2 of the} radial impeller 4, is 0.20 ... 0.48 diameter D _{2 of the} radial impeller 4. The first section of the output edge 8 of the blade 7 with a constant distance to the axis of rotation 9 of the radial impeller 4 is 0.32 ... 0.45 width b _{2 of the} blade 7. The radial impeller 4 is kinematically connected with a drive 10 installed in the cavity of the fairing 11 containing the cylindrical part from the side of the main disk 6 of the radial impeller 4. An axisymmetric input manifold 12 with a curvilinear generatrix is located at the entrance to the radial impeller 4 coaxially with it to form a confuser gap 13 (Fig. four). Between the cylindrical sections of the housing 1 and the fairing 11, a channel 14 is formed with a blade rectifier 3, while the diameter of the cylindrical part of the fan housing 1 does not exceed 1.65 of the diameter D _{2 of the} radial impeller 4, and the diameter of the cylindrical section of the fairing 11 is not less than 1.1 diameter D _{2 of the} radial impeller 4 (Fig. 3, 5-9).

The annular section of the cover disk 5 of the radial impeller from the diameter D _{2 of the} radial impeller 4 to the outer diameter of the cover disk 5 can be made flat, conical with angles forming 50 ... 70 degrees relative to the axis of rotation of the radial impeller 4 and with another form of the generatrix.

The cylindrical section of the fairing 11 from the side of the radial impeller 4 can be equipped with a front wall 15, in which at least one hole (not shown in Fig.) Is made for cooling the actuator 10, and a plug 16 (Fig. 5, 7). The cowling 11 can be performed with a tapered section 17 tapering towards the exit of the channel fan housing 1 adjacent to the cylindrical section of the cowling 11 and equipped with a plug 18 (Fig. 8, 9). For ventilation of the drive 10, the channel fan can be equipped with a pipe 19, pneumatically connected to the fairing 11 and outwardly of the cylindrical body 1 (Fig. 7, 8).

In a preferred embodiment of the channel fan, the blade of the rectifier 3 is made along an arc of a circle without twist along the radius of the housing 1, has installation angles at the inlet 25 ... 45 degrees relative to the circumferential direction, installation angles at the outlet 75 ... 82 degrees relative to the circumferential direction, and the density of the straightening vanes apparatus τ is 0.9-1.2.

The drive 10 may include an electric motor 20, on the shaft of which a radial impeller 4 is mounted (Fig. 3-8), or a bearing assembly 21, on the shaft of which a radial impeller 4 is mounted, while the bearing assembly 21 is kinematically connected to the electric motor 20 mounted on the outer surface of the cylindrical section of the housing 1 of the fan (Fig. 9).

The wall section of the housing 1 at the outlet of the channel fan can be made cylindrical (Fig. 5) or conical in shape with an angle between the generatrix and the axis of rotation 9 within 25 ... 45 degrees (Fig. 3, 6-9).

In order to reduce noise levels at the fan outlet, the cylindrical section of the housing 1 around the rectifier 3 can be made sound-absorbing (for example, from a metal perforated sheet, around which there is a layer of basalt mat).

Channel fan operates as follows.

The flow at the exit of the rotating radial impeller 4 has kinetic energy of rotation and creates a dynamic pressure proportional to 0.5ρu ² , where ρ is the air density, u is the peripheral speed of the ends of the blades 7 on the outer diameter D _{2 of the} radial impeller 4. The presence of straightening blades apparatus 3 at the exit of the radial impeller 4 allows you to translate part of the kinetic energy into potential by increasing the static component of the total pressure of the flow and prevent the loss of total energy due to the reduction of Nia wall of the cylindrical body 1 due to the reduced flow velocity at the flow pattern alignment.

Due to the difference in static pressure in the cavity between the front 2 and inlet 12 manifolds and in the rotating radial impeller 4, an annular air stream is formed in the gap 13, flowing out onto the inner surface of the cover disk 5 (Fig. 4). In this case, the separation of the boundary layer (flow) on the inner surface of the cover disk 5 is delayed. In addition, the increased diameter of the cover disk 5 and the blade 7 with the distance from the axis of rotation of the radial impeller 9 to the exit edge 8 of the blade 7 increasing to the cover disk 5 prevents flow separation from the cover disk 5, which allows to obtain the most uniform flow across the width of the radial impeller 4. The result is an increase in the static and total pressure of the channel fan and its efficiency as in full ohm η, and the static η _s pressure. These measures allow the fan to operate efficiently at different values of the width of the radial impeller b ₂ , referred to its diameter D ₂ , providing high values of efficiency and expanding the working area by the performance factor ϕ up to ϕ = 0.5, which, in turn, allows increase the width of the blades 7 of the impeller 4 up to b ₂ = 0.48D ₂ without impairing its aerodynamic characteristics. Moreover, studies have shown that the shape of the axial radial transition 22 from the conical to the cylindrical shape of the housing 1 weakly affects the restoration of the static component of the total pressure.

A comparison of the dimensionless aerodynamic characteristics of a radial fan with different housings and the same radial impeller 4 is shown in FIG. 10 on the graphs Ψ _S = f (ϕ) and η = f (ϕ), where:

Ψ = 2P _v / ρu ² is the total pressure coefficient,

P _v - total pressure created by the fan,

ρ is the air density;

u = πD ₂ n / 60 is the peripheral speed of the impeller blades,

D ₂ - the diameter of the impeller;

n is the rotation frequency;

Ψ _S = 2P _S / ρu ² is the static pressure coefficient;

P _S - static pressure generated by the fan,

ϕ = Q / (uS) - productivity coefficient,

Q - volumetric fan performance,

₂ S = πD ^2/4 - Area of the impeller;

η = P _v Q / N - coefficient of performance,

N is the mechanical power supplied to the shaft of the radial impeller.

On the graphs, the indices with the coefficients correspond to:

Ψ _channel , η _channel — static pressure coefficient and coefficient of efficiency of the channel fan of the present invention;

Ψ _{channel analogue} , η _{channel analogue} — static pressure coefficient and efficiency of a channel fan without a rectifier, presented in the closest analogue [4], with the same impeller as in this invention;

Ψ _spiral , η _spiral - static pressure coefficient and efficiency of the fan in a spiral case with the same impeller as in this invention.

In accordance with the graphs in FIG. 10, the total pressure coefficient Ψ and the efficiency η of the developed channel fan are close to the total pressure coefficient Ψ and the efficiency η of the same radial impeller in a spiral casing and reach 78% at maximum, unlike the case of using this impeller in a cylindrical casing, which is presented in the closest analogue [4], without a straightener.

The invention is disclosed in a volume sufficient to develop and manufacture a radial duct fan in a specialized enterprise. The invention meets the condition of patentability "industrial applicability".

LIST OF POSITIONS AND DESCRIPTION OF THE INVENTION “CHANNEL FAN”

1 - fan housing;

2 - a front collector;

3 - straightening apparatus;

4 - radial impeller;

5 - cover disk of the impeller;

6 - the main disk of the impeller;

7 - the blade of the impeller;

8 - the output edge of the blades of the impeller;

9 - axis of rotation of the radial impeller 4;

10 - drive radial impeller 4;

11 - fairing drive 10;

12 - input collector;

13 - annular gap between the input manifold 12 and the cover disk of the impeller;

14 - an annular channel between the cylindrical sections of the housing 1 and the fairing 11;

15 - the front wall of the fairing 11;

16 - rear plug of the cylindrical fairing 11;

17 - conical section of the fairing 11;

18 - rear plug conical section 17 of the fairing 11;

19 - pipe for ventilation of the actuator 10;

20 - electric motor drive 11;

21 - bearing assembly;

22 - axial radial transition;

D ₂ - the diameter of the radial impeller 4, equal to the diameter of the circle described by rotation of the output edges of the blades 7 adjacent to the main disk 6;

b ₂ - the width of the blades 7, equal to the distance between the main 6 and cover 5 discs on the diameter D ₂ of the impeller;

Ψ = 2P _v / ρu ² is the total pressure coefficient;

P _v is the total pressure created by the fan;

ρ is the air density;

u = πD ₂ n / 60 is the peripheral speed of the impeller blades;

n is the rotation frequency;

Ψ _S = 2P _S / ρu ² is the static pressure coefficient;

P _S - static pressure created by the fan;

ϕ = Q / (uS) - productivity coefficient;

Q - volumetric fan performance;

₂ S = πD ^2/4 - Area of the impeller;

η = P _v Q / N - coefficient of performance;

N is the mechanical power supplied to the impeller shaft.

Claims (11)

1. A duct or roof fan comprising a housing, a radial impeller, an axisymmetric intake manifold, a cowl, a radial impeller drive, a cowl drive and a straightening apparatus, the housing is made with a cylindrical section, the radial impeller is formed by a main and cover discs with the bent discs located between the discs back by the blades, while the diameter of the radial impeller is the maximum diameter of the mating of the blades with the main disk, the axisymmetric input manifold is made with a curve a frost generatrix located at the entrance to the radial impeller and aligned with it to form a confuser gap between the surfaces of the inlet manifold and the cover disk of the radial impeller, the radial impeller is kinematically connected to the drive, the cowl of the drive is made with a cylindrical section and with a front wall, a straightening device contains blades, is installed in the channel between the cylindrical sections of the fairing and the housing, characterized in that the width of the blades is equal to the distance between the main and the cover claims on the diameter of the radial impeller, is 0.2 ... 0.48 of the diameter of the radial impeller, the output edge of the blades of the radial impeller contains at least two sections characterized by a change in the distance to the axis of rotation of the radial impeller in each of the sections, while the first section adjacent to the main disk, which is 0.32 ... 0.45 of the blade width of the radial impeller, the distance from the axis of rotation to the outlet edge of the blade is kept constant, and in the second section, the distance t of the axis of rotation to the output edge gradually increases as it approaches the cover disk up to the radius of the cover disk, while the diameter of the main disk is 1.01 ... 1.03 of the diameter of the radial impeller, the diameter of the cover of the disk is 1.05 ... 1.15 of diameter radial impeller, the diameter of the cylindrical portion of the fan casing does not exceed 1.65 of the diameter of the radial impeller, and the diameter of the cylindrical portion of the radome of the radial impeller drive is at least 1.1 of the diameter of the radial impeller. 2. The fan according to claim 1, characterized in that the portion of the cover disk of the radial impeller from the diameter of the radial impeller to the outer diameter of the cover disk is flat. 3. The fan according to claim 1, characterized in that the portion of the casing disk of the radial impeller within the diameter of the radial impeller is conical in shape with angles forming 50 ... 70 degrees relative to the axis of rotation of the radial impeller. 4. The fan according to claim 1, characterized in that at least one hole is made in the front wall of the cylindrical radome of the drive of the radial impeller. 5. The fan according to claim 1, characterized in that the radome impeller fairing comprises a conical section adjacent to the cylindrical section, tapering to the fan outlet, ending with a rear end. 6. The fan according to claim 1, characterized in that the rear end of the fairing is equipped with a plug, and a pipe is installed between the housing and the fairing of the drive, pneumatically connected to the fairing and outward of the duct fan housing. 7. The fan according to claim 1, characterized in that the blade of the straightening apparatus is made along an arc of a circle without twist along the radius of the casing, has installation angles at the entrance of 25-45 degrees relative to the circumferential direction, installation angles at the exit of 75-83 degrees relative to the circumferential direction, and the density of the blades of the rectifier is 0.9-1.2. 8. The fan according to claim 1, characterized in that the drive comprises an electric motor on the shaft of which a radial impeller is mounted. 9. The fan according to claim 1, characterized in that the drive comprises a bearing assembly connected by a shaft to a radial impeller, and the bearing assembly is kinematically connected to an electric motor mounted on the outer surface of the duct fan housing. 10. The fan according to claim 1, characterized in that the conical section adjoins the cylindrical section of the casing from the outlet side of the channel fan with an angle between the generatrix and the axis of rotation of the radial impeller within 25 ... 45 degrees. 11. The fan according to claim 1, characterized in that the cylindrical section of the housing around the rectifier apparatus is made sound-absorbing.

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