CN1313737C - Anti-surge ring of axial fan - Google Patents

Abstract

An anti-surge ring for an axial flow fan belongs to the technical field of fan and ventilation engineering. The anti-surge ring is a part of the casing of the axial flow fan used in the tunnel. It is composed of an outer ring, an inner ring, and a ring. The diameter of the outer ring is the same, the inner diameter of the ring is the same as the diameter of the inner ring, the number of outer rings is between 2 and 5, the number of inner rings is 1 less than the number of outer rings, and the number of rings is twice the number of inner rings. The most common form of anti-surge ring consists of 3 outer rings, 2 inner rings and 4 circular rings. The front and rear edges of the blade top of the axial flow fan are respectively located at the concave space positions at the front and back of the anti-surge ring. The concave space of the anti-surge ring inhibits the development of inlet vortices. Therefore, the anti-surge ring can delay the occurrence of fan surge, or even prevent it from occurring. Since the anti-surge ring is front-to-back symmetrical, the same anti-surge effect will be produced when the fan is reversed in subway, railway, and road tunnels that require two-way ventilation.

Description

Axial fan anti-surge ring

technical field

The invention relates to an anti-surge ring for an axial flow fan, in particular to an anti-surge ring for an axial flow fan suitable for subways or tunnels, and belongs to the technical field of fans and ventilation engineering.

Background technique

With the development of the country's economy, my country's transportation industry has also experienced extraordinary development. There are more and more subways in cities, railways passing through mountains, and road tunnels. Due to the limited height and length of the tunnel, ventilation in the tunnel is particularly important. At present, the ventilation problems in subways, railways, and highway tunnels are mainly borne by medium and large axial flow fans. However, due to the blockage of the ventilation pipe network and the muffler, or the piston wind effect caused by the reverse running of subway trains and automobiles, the instantaneous back pressure is too large, and the air volume of the fan drops sharply. Cause the fan to stall, surge, and cause severe vibration, and in severe cases, the fan will be damaged. In order to provide people with a safe and reliable traffic environment, it is necessary to eliminate the surge of the axial flow fan. Eliminating or weakening the backflow of the airflow at the top of the fan blade inlet can suppress the occurrence of surge, or shift the surge point to a place with a smaller flow rate, reducing the possibility of surge.

In the existing technology, the patent number is ZL 00218027.8, and the utility model patent named "anti-surge device of axial flow fan" adopts "evenly distributed guide vanes" "between the shell and the inner ring", and "all The axial inclination angle of the guide vanes in the outer shell and the inner ring can be 30°-90°, and the number of guide vanes can be 30-150". Therefore, the difficulty of production has been increased; the patent number is ZL 01105719.x, and the invention patent named "Tunnel Jet Fan Anti-Surge Device" uses the inner simplified "is a rotating body with the axis of the fan as the axis. The outer surface of the fan is composed of a cylindrical surface and an arc surface. Because the machining of the arc surface is difficult, and the radial size of the fan increases greatly, it occupies valuable space in the tunnel. The patent number is CN 2448969, and the utility model patent titled "Anti-surge Axial Flow Fan" states that "the anti-surge ring includes a vortex collecting groove, and a group of worm-elimination plates are evenly arranged in the vortex-collecting groove along the circumferential direction, and inside the worm-eliminating plates A rectifying ring is arranged near the blade, and a guide ring is installed on the side of the vortex near the end of the blade." This structure is very complicated and time-consuming and labor-intensive during installation.

Contents of the invention

In order to overcome the deficiencies and defects of the prior art and improve the working conditions of the axial flow fan at low flow rate, the present invention designs a structure which is simpler and more reasonable, which is convenient to process and can effectively eliminate the possible stall, Anti-surge ring for surge phenomenon.

The anti-surge ring is a circular body with front and back symmetry along the direction of airflow, with alternating concave and convex shapes. It is a part of the casing of the axial flow fan for tunnels and is installed at the position of the impeller blades. The present invention includes an outer ring, an inner ring and a circular ring. The outer diameter of the ring is consistent with the diameter of the outer ring; the inner diameter of the ring is consistent with the diameter of the inner ring. The number of outer rings is between 2 and 5, the number of inner rings is 1 less than the number of outer rings, and the number of rings is twice the number of inner rings. The most common form of anti-surge ring consists of 3 outer rings, 2 inner rings and 4 circular rings. One end of the first outer ring is welded to the outer diameter end of the first ring, the inner diameter end of the first ring is welded to one end of the first inner ring, and the other end of the first inner ring is welded to the second ring The inner diameter end of the ring is welded, the outer diameter end of the second ring is welded to one end of the second outer ring, in this order, until the outer diameter end of the fourth ring is welded to one end of the third outer ring, the After the anti-surge ring is welded and formed, flanges are respectively welded at its front and rear ends so as to be connected with the front and rear shells of the axial flow fan. A concave space is formed between the front and rear ends of the anti-surge ring and the flange. When matched with an axial flow fan, the front and rear edges of the blade top of the axial flow fan are respectively located in the concave space before and after the anti-surge ring, and the gap between the top of the blade and the inner ring acts as a seal for the axial air flow.

When the axial flow fan is working, as the flow rate of the fan decreases, a vortex gradually appears at the inlet of the blade top of the axial flow fan, and the vortex increases continuously with the decrease of the flow rate. However, after the axial flow fan is equipped with an anti-surge ring, the inlet vortex is located near the concave space of the anti-surge ring, and the concave space of the anti-surge ring will inhibit the development of the inlet vortex. Therefore, the anti-surge ring can delay the occurrence of fan surge, or even prevent it from occurring. When performing a performance comparison test on a certain axial flow fan, the axial flow fan equipped with an anti-surge ring, when the flow rate decreases, its wind pressure rises by an average of 10% compared with the axial flow fan without an anti-surge ring about. Since the anti-surge ring of the present invention is front-to-back symmetrical, the same anti-surge effect will be produced when the fan is reversed in tunnels of subways, railways and roads that require two-way ventilation.

The invention has the advantages of simple structure, convenient processing, obvious anti-surge effect, and remarkable social and economic benefits.

Description of drawings

Fig. 1 is a structural schematic diagram of an anti-surge ring of an axial flow fan.

Figure 2 is a perspective view of the anti-surge ring,

In the figure, 1 is an outer ring, 2 is a ring, 3 is an inner ring, 4 is a flange, 5 is a concave space, and 6 is a blade.

Figure 3 is a performance comparison diagram of the axial flow fan before and after installing the anti-surge ring,

The curve with "◆" in the figure is the performance curve of the fan without anti-surge ring; the curve with "■" is the performance curve of the fan with anti-surge ring installed.

Detailed ways

The specific implementation of the present invention will be further described below in conjunction with accompanying drawing:

As shown in FIG. 1 and FIG. 2 , the present invention includes an outer ring 1 , a circular ring 2 and an inner ring 3 . The outer diameter of the ring 2 is consistent with the diameter of the outer ring 1; the inner diameter of the ring 2 is consistent with the diameter of the inner ring 3. The number of the outer ring 1 is between 2 and 5, the number of the inner ring 3 is 1 less than the number of the outer ring 1, and the number of the ring 2 is twice the number of the inner ring 3 . The most common form of an anti-surge ring consists of 3 outer rings 1 , 2 inner rings 3 and 4 circular rings 2 . One end of the first outer ring 1 is welded to the outer diameter end of the first ring 2, the inner diameter end of the first ring 2 is welded to one end of the first inner ring 3, and the other end of the first inner ring 3 is welded Weld with the inner diameter end of the second ring 2, weld the outer diameter end of the second ring 2 with one end of the third outer ring 1, in this order until the outer diameter end of the fourth ring 2 and the third One end of the three outer rings 1 is welded. After the anti-surge ring is welded and formed, flanges 4 are welded at the front and rear ends of the anti-surge ring, so as to be connected with the front and rear shells of the axial flow fan. A concave space 5 is formed between the front and rear ends of the anti-surge ring and the flange 4 . When matched with an axial flow fan, the top front and rear edges of the axial flow fan blades 6 are respectively located in the concave space 5 before and after the anti-surge ring, and the gap between the top of the blade 6 and the inner ring 3 plays a role in the axial flow. Sealing effect.

In addition to welding and forming, the anti-surge ring of axial flow fan can also be formed by stamping. First, the forming mold is opened according to the shape of concave and convex, and the rectangular iron plate is cut according to the required size, and then welded into a flat ring, and then formed. Die roll forming.

When the axial flow fan is working, as the flow rate of the fan decreases, a vortex gradually appears at the inlet of the blade 6 of the axial flow fan, and the vortex increases continuously with the decrease of the flow rate. However, after the axial flow fan is equipped with an anti-surge ring, the inlet vortex is located near the concave space 5 of the anti-surge ring, and the concave space 5 of the anti-surge ring will inhibit the development of the inlet vortex. Therefore, the anti-surge ring can delay the occurrence of fan surge, or even prevent it from occurring. As shown in Figure 3, when performing a performance comparison test on an axial flow fan, the axial flow fan equipped with an anti-surge ring, when the flow rate decreases, its wind pressure is higher than that of the axial flow fan without an anti-surge ring Fans have risen by around 10% on average. Since the anti-surge ring of the present invention is front-to-back symmetrical, the same anti-surge effect will be produced when the fan is reversed in tunnels of subways, railways and roads that require two-way ventilation.

Claims (3)

1. An anti-surge ring of an axial flow fan is a part of an axial flow fan casing for a tunnel, and is characterized in that the anti-surge ring is composed of an outer ring (1), an inner ring (3), a ring (2) Composed of a circular body that is symmetrical in front and back along the airflow direction, and has a concave-convex shape, the outer diameter of the ring (2) is consistent with the diameter of the outer ring (1), and the inner diameter of the ring (2) is the same as that of the inner ring (3). The diameters are the same, the number of outer rings (1) is between 2 and 5, the number of inner rings (3) is 1 less than the number of outer rings (1), and the number of rings (2) is twice the number of inner rings (3), The anti-surge ring is installed at the position of the blade, and a concave space (5) is formed between its front and rear ends and the flange (4). Space (5) position. 2. The anti-surge ring of axial flow fan according to claim 1, characterized in that the anti-surge ring usually consists of 3 outer rings (1), 2 inner rings (3) and 4 circular rings (2 ), one end of the first outer ring (1) is welded to the outer diameter end of the first ring (2), and the inner diameter end of the first ring (2) is welded to one end of the first inner ring (3) Welding, the other end of the first inner ring (3) is welded to the inner diameter end of the second ring (2), the outer diameter end of the second ring (2) is welded to one end of the second outer ring (1) Welding, in this order, until the outer diameter end of the fourth ring (2) and one end of the third outer ring (1) are welded, after the anti-surge ring is welded, flanges are welded at its front and rear ends respectively (4). 3. The anti-surge ring of axial flow fan according to claim 1, characterized in that the anti-surge ring of axial flow fan can also be formed by rolling, and the forming mold is first opened according to the shape of concave and convex, and press Cut the rectangular iron plate to the required size, weld it into a flat ring, and then roll it on the forming die.

Images