RU2429385C1 - Radial wheel rotor - Google Patents

Abstract

FIELD: engines and pumps. ^ SUBSTANCE: proposed wheel rotor comprises main and front plates, rotor vanes arranged between said plates and bent back relative to direction of rotation. Mote here that each vane has cutout on rear edge located at distance making not over 0.5 of vane width at wheel rotor outlet. Note also that vane section between front plate and said cutout is bent toward direction of rotation. ^ EFFECT: higher discharge and efficiency. ^ 10 cl, 13 dwg

Description

The invention relates to the field of fan engineering, namely to radial impellers of fans and compressors.

Radial impellers are known in the art.

So, in USSR author's certificate No. 1760176, F04D 29/28, publication date 08/23/1991 [1], the impeller of a centrifugal compressor is presented, containing the front and main disks with vanes installed between them, at least one of the vanes on the trailing edge two slots that divide the trailing edge into separate sections, which are made with different exit angles in alternating order. This embodiment of the impeller of a centrifugal compressor provides dispersion of the flow in the circumferential direction with the achievement of intensification of energy exchange, which leads to a reduction in hydraulic losses and, consequently, an increase in the efficiency of the impeller. According to the description of the invention [1], at least two slots are made on the outlet edge of the blade, and the problem of increasing the width of the impeller blades by providing continuous flow around the front disc is not considered.

In USSR author's certificate No. 580358, IPC F04D 29/28, F04D 27/00, publication date 11/15/1977 [2] a method for controlling a centrifugal fan is presented, according to which, when a fan is operating at high capacity in a radial impeller containing the front and the main disks and backward curved blades installed between them, having a main part and flaps that deflect, giving the blade an S-shape. In this case, the flaps are located over the entire width of the blade at the exit of the impeller. This increases the efficiency (hereinafter the efficiency) of the impeller.

In the description of the utility model for the certificate of the Russian Federation No. 22978, IPC F04D 29/28, F04D 29/66, publication date 05/10/2002 [3] a radial impeller is presented containing the front and rear discs and the curved blades installed between them back. This impeller is commercially available with blade widths up to 0.37 impeller diameters, but its aerodynamic characteristics and efficiency, as shown by studies, can be improved.

In the description of the invention to the patent of the Russian Federation No. 2330189, IPC F04D 29/28, F04D 29/66, publication date July 27, 2008 [4] a radial impeller is presented comprising a front and main discs and curved blades mounted between them backward, each of which is equipped with a slat - a section closer to the axis of rotation of the impeller from the point of abutment of the main part of the blade to the surface of the front disk, while in the projection onto a plane perpendicular to the axis of rotation of the impeller, the nose of the front edge of the slat of the blade following the rotation of the blade It goes beyond the sector formed by the axis of rotation of the outgoing beams at angles of ± 0,05 angular pitch of the blades relative to the straight line connecting the impeller rotational axis and the point of abutment of the blade to the front of the previous drive. This embodiment of the impeller reduces the sound power level by reducing the sound power levels at the blade frequencies and their harmonics. However, studies have shown that its aerodynamic characteristics and efficiency can be improved while maintaining the effect of reducing the sound power of the radial impeller.

As the closest analogue of the invention adopted radial impeller, presented in the description of the utility model for the patent [3].

The problem to be solved by the invention is to tighten the separation of the flow from the front disk in the interscapular space of the impeller.

The technical result of the invention is to increase the efficiency and increase the coefficient of static pressure of the radial impeller.

The invention consists in the following.

The radial impeller, as in the closest analogue [3], contains the main and front disks located between the disks of the impeller blades, made curved back relative to the direction of rotation, but unlike the closest analogue [3], each blade is made with a slot on the trailing edge located from the front disk at a distance of not more than 0.5 of the width of the blade at the exit of the impeller, while part of the blade between the front disk and the slot is made bent in the direction of rotation.

In this case, the slot is made in a plane perpendicular to the axis of rotation of the impeller.

The radial impeller is characterized in that each impeller blade is equipped with a slat - a section located closer to the axis of rotation of the impeller from the abutment of the main part of the blade to the surface of the front disk, with the nose of the leading edge of the slat next to the rotation of the blade in a projection onto a plane perpendicular the axis of rotation of the impeller, does not go beyond the boundaries of the sector formed by the rays emanating from the axis of rotation at angles ± 0.05 of the angular pitch of the blades relative to a straight line connecting th axis of rotation of the impeller and the point of contact of the previous blades to the front disk.

In this case, the lateral edge of the slat is located at an acute angle to the leading edge of the slat.

In addition, the leading edge of the blade is set at an angle of ± 10 degrees. to a plane perpendicular to the axis of rotation of the impeller.

The radial impeller is characterized in that the leading edge of the slat of the wheel blade is curved.

The radial impeller is characterized in that the leading edge of the impeller is made in an arc of a circle.

The radial impeller is characterized by the fact that 13 blades are installed on the impeller, the front edge of the main part of the blade at the section adjacent to the front disk is straight, the main part of the blade connected to the front disk is flat, and the front disk at this section is made in accordance with equations:

y = (0.29 + 0.01) x + 0.37,

z = (- 0.39 + 0.01) x-0.27,

r ² = x ² + y ² ,

where: z = Z / D is the relative coordinate directed along the axis of rotation of the impeller in the direction from the main disk to the entrance to the impeller;

x = X / D is the relative coordinate perpendicular to the axis of rotation of the impeller;

y = Y / D is the relative coordinate perpendicular to the z axis and x axis;

r = R / D is the relative radius of the impeller,

R is the current radius of the impeller;

X, Y, Z - current coordinates;

D is the diameter of the impeller.

In addition, the radial impeller is characterized in that the width of the blade at the exit of the impeller is at least 0.25 times the diameter of the impeller.

The radial impeller is characterized in that the diameter of the front disc is 1.05 ... 1.2, and the diameter of the main disc is 1.05 ... 1.15 of the diameter of the impeller.

The invention is illustrated by drawings.

In figure 1. The meridional section of the impeller is presented.

Figure 2 shows a section aa in figure 1.

Figure 3 presents the meridional section of the impeller, the blades of which are equipped with slats.

Figure 4 shows a section bB in figure 3.

Figure 5 shows a blade with a flat main part and a slat.

Figure 6 shows a view In figure 5.

7 shows a meridional section of a radial impeller with enlarged front and rear discs.

On Fig shows a longitudinal section of a channel fan used for comparative tests.

Figure 9 shows the pressure characteristic of a duct fan with impellers with blades without a slat.

Figure 10 shows the dependence of the efficiency on the coefficient of performance of the duct fan with impellers with blades without a slat.

11 shows the pressure characteristic of a duct fan with impellers with vanes with slats.

On Fig shows the dependence of the efficiency on the coefficient of productivity of a free radial impeller with blades with a slat.

On Fig shows the dependence of the efficiency on the coefficient of performance of the channel fan with impellers with blades at different distances from the front disc of the slot on the trailing edge of the blade.

Disclosure of the invention.

The radial impeller contains a front 1 and a main 2 disks, vanes 3 installed between them. The impeller is equipped with a sleeve (not marked) for connection with an electric drive. The input 4 of the air flow into the impeller is located in a plane formed by the leading edges of the front disc 1, and the output 5 of the air flow from the impeller is located between the outer edges of the front 1 and the main 2 discs (Fig. 1). The width H of the blade 3 of the impeller is determined by the distance between the front 1 and the main 2 disks at the output 5 of the impeller. The blades 3 are made curved back (figure 2). Each of the blades 3 has a slot 6 with a limb 7, located mainly in the plane perpendicular to the axis of rotation 7 of the impeller (figure 1). We call the part of the blade 3 from the trailing edge 8 to the end of the slot 6 a flap 9, and the part of the blade 3 at the edge of the edge 10 to the front disk 1 from the slot 6 in the direction of the axis of rotation 7 - the main part 11 of the blade 3. Moreover, the part of the flap 9 of the blade 3 between the slot 6 and the front disk 1 is made with a limb 12 in the direction of rotation of the impeller (figure 2).

Each blade 3 of the radial impeller can be equipped with a slat 13 - a section of the blade 3 located between the main part 11 of the blade 3 and the axis of rotation 7 of the impeller (figure 3). Moreover, in the projection onto the plane perpendicular to the axis of rotation of the impeller, the nose 14 of the next blade 3A along the rotation does not extend beyond the boundaries of the sector formed by rays emanating from the rotation axis 7 at angles Δt equal to ± 0.05 of the angular step t = 2π / n blades 3 with respect to a straight line connecting the axis of rotation of the impeller 7 and the abutment point 15 of the leading edge 16 of the slat 13 to the front disk 1 (Fig. 4), and the lateral edge 17 of the slat 10 is located at an acute angle to the leading edge 15 of the slat 13 (Fig. .3): Δt = ± 0.05t = ± 0.05 · 2π / m, where m is the number of blades atok.

The leading edge 16 of the slat 13 of the blade 3 can be installed at an angle of ± 10 degrees. to the plane perpendicular to the axis of rotation of the impeller 7, the trailing edge 8 of the blades 3 can be performed as rectilinear (figure 5, 6), and curved (not shown).

The edge 10 of the blade 3 adjacent to the front disk 1, can be curved, for example, along an arc of a circle or another curve (not shown), and rectilinear (figure 1, 5). When performing the impeller with 13 blades 3, the edges 10 of the rectilinear and the main part 11 of the blades 3, the flat generatrix of the front disk 1 at the abutment of the edge 10 of the blades 3 is made in accordance with the equations

y = (0.29 + 0.01) x + 0.37,

z = (- 0.39 + 0.01) x-0.27,

r ² = x ² + y ² ,

where: z = Z / D is the relative coordinate directed along the axis of rotation of the impeller 7 in the direction from the main disk 2 to the input 4 of the impeller;

x = X / D is the relative coordinate perpendicular to the axis of rotation 7 of the impeller;

y = Y / D is the relative coordinate perpendicular to the z axis and x axis;

r = R / D is the relative radius of the impeller,

R is the current radius of the impeller;

X, Y, Z - current coordinates;

D is the diameter of the impeller, that is, the diameter of the circle described by the trailing edges 8 of the blades 3 of the impeller.

The impeller can be performed with increased diameters of the front disk 1 to 1.05 ... 1.2 and the main disk 2 to 1.05 ... 1.10 of the diameter D of the impeller (Fig.7), which helps to increase the efficiency of the impeller. The presence of a slot 6 with a bend 12 allows you to increase the width H of the blade 3 of the impeller to 0.25 or more of the diameter D of the impeller.

In a preferred embodiment, the main part 11 of the blade 3 of the radial impeller is made flat, the edges 10 are straight, the slot 6 with a bend 12 on the flap 9 is made at 30% of the width H of the trailing edge 8 of the blade 3 from the front disk 1, the impeller is equipped with 13 blades, and the generatrix of the front disk 1 is made in accordance with the system of equations:

y = (0.29 ± 0.01) x + 0.37; z = (- 0.39 ± 0.01) x-0.27; r ² = x ² + y ²

The impeller operates as follows.

The flow in the impeller of a radial fan with backward-curved blades depends mainly on the shape of the blades, the angles of installation of the blades at the inlet and outlet, the shape of the front disk and the width of the impeller. One of the main factors is the presence of a tear-off current near the front disk. If the flow in the impeller is such that a separation occurs at the front disc, then the fan pressure drops and its efficiency decreases. The more the vanes are bent backward, the wider wheels work stably, without separation of flow at the front disk, but at the same time, the impeller can provide smaller ranges in terms of productivity coefficient. To obtain the highest performance at the given fan sizes and blade angles, it is necessary to increase the width of the impeller, but when a certain maximum width of the impeller blades is reached, it is no longer possible to maintain a continuous flow near its front disk. Thus, one of the main tasks is to ensure a steady continuous flow at the front disk in the interscapular space of the radial impeller.

To substantiate the achievement of the technical result of the present invention, comparative aerodynamic tests of the declared radial impellers and the radial impeller adopted as the closest analogue were carried out. Radial impellers with a diameter of D = 400 mm and a blade width of 3H = 148 mm (which is 37% of the diameter D of the impeller) were placed in a commercially available duct fan case with a square cross section and dimensions between the channel walls of 556 mm. In this case, engines of the same type were used with the same power (Fig. 8). Slot 6 with a limb 12 is characterized by the following relative values (Fig.6):

k = K / H is the relative distance of the slot 6 from the front disk 1, equal to the ratio of the distance K of the slot 6 from the front disk 1 to the width H of the blade 3;

C - depth of the slot 6 - distance from the trailing edge 8 of the non-bent part of the flap 9 of the blade 3 to the base of the slot 6; in all tests, the depth C of the slot 6 was constant: C = 14 mm;

a = A / H - relative bending - the ratio of the distance A between the trailing edges 8 of the flap 9 in the bent and initial position to the width H of the blade 3.

A comparison of the pressure aerodynamic characteristic ψ _s = (φ) and efficiency η _S = f (φ) versus the performance coefficient φ installed in the channel fan housing of the declared and adopted as the closest analogue [3] of radial impellers with blades without slats is shown in FIG. .9, 10, and with blades with a slat - 11, 12.

The designations are adopted in accordance with GOST 10616-90 "Radial and axial fans":

ψ _S = 2P _SV / (ρu ² ) is the static pressure coefficient;

φ = Q / (Fu) - fan performance coefficient;

η _S = QP _SV / N - static fan efficiency;

P _SV - static pressure of the fan, Pa;

F = πD ^2/4 - Impeller area, m ^2;

u = πDn / 60 - peripheral speed of the impeller, m / s;

n is the frequency of rotation of the impeller, rpm;

Q - fan performance, m ³ / s;

D is the diameter of the impeller, m

As shown in the graphs ψ _S = (φ) in Fig. 9 and η _S = f (φ) in Fig. 10, the presence of a slit 6 and a limb leads to an increase in the static pressure coefficient ψ _S and the static efficiency η _{S of the} fan at the same performance factor fan φ in comparison with the radial impeller adopted as the closest analogue [3], i.e. radial impeller without a slot and bending at the trailing edge of the blades (not shown in Fig.).

The same result is achieved by equipping the blades 3 of the radial impeller with the slats 13 shown in the analogue [4], namely, in the graphs ψ _S = (φ) in Fig. 11 and η _S = f (φ) in Fig. 12, it is shown that the presence of a slot 6 and a limb 12 leads to an increase in the static pressure coefficient ψ _S and static efficiency η _{S of the} fan with the same fan efficiency coefficient φ compared to a radial impeller with blades with slats and without a slot and bend (not shown). Moreover, in comparison with the closest analogue [3] on radial impellers with blades 3 with a slat 13, both with a slot 6 and a bend 12, and without them, the sound power level at the blade frequencies and their harmonics decreases.

The graph η _S = f (φ) shown in Fig. 13 for different relative distances k = K / H from the front disk 1 of the slot 6 and the bend 12 along the width of the trailing edge 8 of the blade 3 shows that there is an optimal position of the slot 6 not exceeding k = 0.5 of the width N of the blade 3 from the front disk 1 of the radial impeller.

Thus, experimental studies confirm the materiality of the claimed features to achieve the claimed technical result.

The level of disclosure of the invention is sufficient for the implementation of the radial impeller and its blades 3 both in the development and in the manufacture of the blades 3 and radial impellers.

LIST OF POSITIONS AND DESIGNATIONS IN THE DESCRIPTION OF THE INVENTION "RADIAL WORKWHEEL"

1 - front drive;

2 - the main disk;

3 - blades;

3A - the blade following the blade 3 in the direction of rotation;

4 - air flow inlet to the impeller;

5 - air flow output from the impeller;

6 - slot;

7 - axis of rotation of the impeller;

8 - the trailing edge of the blade 3;

9 - flap blades 3;

10 - the edge of the part of the blade 3 adjacent to the front disk 1.

11 - the main part of the blade 3;

12 - bending of the flap portion 9 of the blade 3 between the slot 6 and the front disk 1;

13 - slat blades 3;

14 - toe of the leading edge 16 of the slat 12;

15 - the point of contact of the blades 3 to the surface of the front disk 1;

16 - the leading edge of the slat 13;

17 - the lateral edge of the slat 13;

H - the width of the blades 3 of the impeller, equal to the distance between the front 1 and the main 2 disks at the exit of 5 air from the impeller;

Δt = ± 0.05t = ± 0.05 · 2π / m is the sector of the permissible position of the point of contact of the blade 3 to the front disk 1 relative to the straight line connecting the axis of rotation 7 and the toe of the next blade 3A;

t = 2π / m is the angular pitch of the blades 3;

m is the number of blades 3;

z = Z / D is the relative coordinate directed along the axis of rotation of the impeller 7 in the direction from the main disk 2 to the input 4 of the impeller;

x = X / D is the relative coordinate perpendicular to the axis of rotation 7 of the impeller;

y = Y / D is the relative coordinate perpendicular to the z axis and x axis;

r = R / D is the relative radius of the impeller,

R is the current radius of the impeller;

X, Y, Z - current coordinates;

D is the diameter of the impeller, equal to the diameter of the circle described by the ends of the blades 3 of the impeller.

ψ _S = 2P _SV / (ρu ² ) is the static pressure coefficient;

φ = Q / (Fu) - fan performance coefficient;

η _S = QP _SV / N - static fan efficiency;

P _SV - static pressure of the fan, Pa;

N is the power consumption of the radial impeller of the fan, W;

F = πD ^2/4 - the area of the radial impeller, m ^2;

u = πDn / 60 - peripheral speed of the impeller, m / s;

n is the frequency of rotation of the impeller, rpm;

Q - fan performance, m ³ / s.

k = K / H is the relative distance of the slot 6 from the front disk 1, equal to the ratio of the distance K of the slot 6 from the front disk 1 to the width H of the blade 3;

C is the depth of the slot 6 is the distance from the trailing edge 8 of the non-bent portion of the flap 9 of the blade 3 to the base of the slot 6;

α = A / H - relative limb 12 - the ratio of the distance A between the trailing edges 8 of the flap 9 of the blades 3 in the bent and initial positions to the width H of the blade 3.

Claims (10)

1. A radial impeller, containing the main and front disks located between the disks of the impeller blades, made curved back relative to the direction of rotation, characterized in that each blade is made with a slot on the trailing edge located from the front disk at a distance of not more than 0.5 the width of the blade at the exit of the impeller, while part of the blade between the front disk and the slot is made bent in the direction of rotation. 2. The radial impeller according to claim 1, characterized in that the slot is made in a plane perpendicular to the axis of rotation of the impeller. 3. The radial impeller according to claim 1, characterized in that each impeller blade is equipped with a slat - a section located closer to the axis of rotation of the impeller from the junction of the main part of the blade to the surface of the front disk, while the nose of the front edge of the slat next along rotation of the blade in the projection onto a plane perpendicular to the axis of rotation of the impeller does not go beyond the boundaries of the sector formed by the rays emanating from the axis of rotation at angles ± 0.05 of the angular pitch of the blades relative to a straight line, soy inyayuschey impeller rotation axis and the point of abutment of the blade to the front of the previous drive. 4. The radial impeller according to claim 3, characterized in that the lateral edge of the slat is at an acute angle to the leading edge of the slat. 5. The radial impeller according to claim 3 or 4, characterized in that the front edge of the blade is installed at an angle of ± 10 degrees. to a plane perpendicular to the axis of rotation of the impeller. 6. The radial impeller according to claim 3 or 4, characterized in that the front edge of the slat of the wheel blades is made curved. 7. The radial impeller according to claim 3 or 4, characterized in that the front edge of the blade of the wheel is made in an arc of a circle. 8. The radial impeller according to claim 1 or 3, characterized in that 13 blades are mounted on the impeller, the edge of the main part of the blade at the section adjacent to the front disk is straight, the main part of the blade connected to the front disk is flat, and forming the front disk in this section is made in accordance with the equations:
y = (0.29 + 0.01) x + 0.37;
z = (- 0.39 + 0.01) x-0.27;
r ² = x ² + y ² ,
where z = Z / D is the relative coordinate directed along the axis of rotation of the impeller in the direction from the main disk to the entrance to the impeller;
x = X / D is the relative coordinate perpendicular to the axis of rotation of the impeller;
y = Y / D is the relative coordinate perpendicular to the z axis and x axis;
r = R / D is the relative radius of the impeller,
R is the current radius of the impeller;
X, Y, Z - current coordinates;
D is the diameter of the impeller. 9. The radial impeller according to claim 1 or 3, characterized in that the width of the blade at the exit of the impeller is at least 0.25 of the diameter of the impeller. 10. The radial impeller according to claim 1 or 3, characterized in that the diameter of the front disk is 1.05 ... 1.2, and the diameter of the main disk is 1.05 ... 1.15 of the diameter of the impeller.

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