JPH0519599U - Axial fan air separator - Google Patents

Abstract

(57) [Summary] [Purpose] The purpose is to reduce pressure loss in the air separator and improve circulation. [Structure] An axial flow provided in an annular shape on the outer circumference of the casing, having an inlet facing the upstream end of the rotor blade, an outlet opening on the upstream side, and a plurality of rectifying vanes for rectifying the flow in the axial direction The inlet side wall of the outer wall of the air separator of the fan is provided so as to be inclined toward the upstream side.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to an air separator for an axial fan that is used for sending various gases.

[0002]

[Prior Art]

 3 and 4 are explanatory views of an air separator used in a conventional axial flow fan. In FIG. 3, the air separator is annularly provided on the outer periphery of the casing 6 of the axial fan in order to improve the unstable characteristics of the axial fan in the low flow rate region. 3 is the tip of the moving blade 2, 6 is a casing, 4 is the outer wall of the air separator made by cutting out a part of the casing 6 upstream from the tip 3 of the moving blade 2, 5 is the inner wall of the air separator, and 7 is the outer wall. A plurality of straightening vanes mounted between the inner wall 4 and the inner wall 5 are arranged so as to straighten the circulating flow in the rotor axial direction. Reference numerals 10 and 11 denote a front wall and a rear wall of the outer wall 4 of the air separator, which are provided perpendicularly to the rotor shaft.

When the flow rate of the axial fan is reduced, a small backflow portion is generated at a part of the tip 3 of the moving blade 2. This gradually grows to form a swirling stall or a backflow region and an axial fan stall occurs. However, by equipping the air separator, the front edge side of the tip 3 of the rotor blade 2 of the casing 6 is opened, and the backflow part is opened. Will enter the air separator as shown by arrow 8 due to centrifugal force. The counterflow portion rotates together with the moving blades 2 and has a higher rotational speed than the mainstream portion, so that the centrifugal force is large. Then, the backflow portion that has entered the air separator is turned inside the air separator, is straightened in the axial direction by the straightening vanes 7, and joins the flow on the upstream side of the moving blade 2 as shown by an arrow 9. The circulation of the backflow section stabilizes the flow and delays the stall of the axial fan.

[0004]

[Problems to be solved by the device]

 FIG. 4 is a characteristic curve diagram of an axial fan. In the figure, the solid line is the characteristic curve when the air separator is not provided. For example, the flow rate and pressure at the point 32 cause the axial fan to stall or surging. The dotted line is a characteristic curve when an air separator is provided. In this case, even if the flow rate is narrowed far beyond the point 32, the stall of the axial fan does not occur.

As described above, since the air separator of the axial fan circulates the backflow portion of the flow in the air separator to rectify the circulating flow and join the flow on the upstream side, the circulation in the air separator The good or bad performance slows down the stall of the axial fan and affects the effect of improving the characteristics of the axial fan. Therefore, in order to further improve the characteristics of the axial fan, it is necessary to improve the circulation property of the air separator.

[0006]

[Means for Solving the Problems]

 The air fan for an axial fan according to the present invention is intended to solve the above-mentioned problems, and is provided in an annular shape on the outer periphery of the casing and has an inlet facing the upstream end of the moving blade and an outlet opening on the upstream side. An air separator of an axial fan, which is provided with a plurality of rectifying vanes for rectifying a flow in an axial direction, is characterized in that an inlet-side side wall of an outer wall is inclined toward an upstream side.

Further, the air separator of the axial fan according to the present invention is characterized in that, in addition to the above-mentioned configuration, the outlet side wall of the outer wall is further inclined and provided on the upstream side.

[0008]

[Action]

 That is, in the air separator of the axial fan according to the present invention, the annular fan is provided on the outer periphery of the casing and has an inlet facing the upstream immediate tip of the moving blade and an outlet opening on the upstream side to allow the flow to flow in the axial direction. The inlet side wall of the outer wall of the air separator of the axial fan provided with a plurality of rectifying vanes for rectifying is sloping to the upstream side, which causes the backflow part of the flow generated at the tip of the rotor blade. Becomes more likely to flow uniformly into the flow regulating vanes in the air separator, reducing the pressure loss in the air separator and improving circulation.

In addition, in the air separator of the axial fan according to the present invention, in addition to the above-described structure, the outlet side wall of the outer wall is further provided so as to be inclined toward the upstream side, which is generated at the tip of the moving blade. The backflow part of the flow becomes easier to uniformly flow into the straightening vanes in the air separator, and the circulation flow passing through the straightening vanes is guided so as to flow along the side wall on the outlet side and the velocity component in the same direction as the flow on the upstream side. Is more likely to be combined with the flow on the upstream side, the pressure loss in the air separator is reduced, and circulation is improved.

[0010]

【Example】

 1 and 2 are explanatory views of an air separator of an axial fan according to an embodiment of the present invention. In the figure, the air separator of the axial flow fan according to the present embodiment is an axial flow fan used for sending various gases, etc., and the axial separator is used to improve the unstable characteristics in the low flow rate range of the axial flow fan. It is provided in an annular shape on the outer periphery of the casing 6 of the flow fan. 1 is a rotor, 2 is a moving blade, 3 is a tip of the moving blade 2, 6 is a casing, and 4 is a casing 6 upstream from the tip 3 of the moving blade 2. The outer wall of the air separator made by cutting out a part of the inner wall of the air separator, 5 is the inner wall of the air separator, and 7 is a plurality of rectifying vanes mounted between the outer wall 4 and the inner wall 5, for rectifying the circulating flow in the axial direction of the rotor. Are arranged so that Reference numerals 10 and 11 denote a front wall and a rear wall of the air separator outer wall 4, respectively.

When the flow rate of the axial fan is reduced, a small backflow portion is generated at a part of the tip 3 of the moving blade 2. This gradually grows to form a swirling stall or a backflow region to stall the axial fan, but by installing an air separator, the front edge side of the tip 3 of the rotor blade 2 of the casing 6 is opened and the backflow part is opened. Will enter the air separator as shown by arrow 8 due to centrifugal force. The counterflow portion rotates together with the moving blades 2 and has a higher rotational speed than the mainstream portion, so that the centrifugal force is large. Then, the backflow portion that has entered the air separator is turned inside the air separator, is straightened in the axial direction by the straightening vanes 7, and joins the flow on the upstream side of the moving blade 2 as shown by an arrow 9. The circulation of the backflow section stabilizes the flow and delays the stall of the axial fan.

As described above, since the air separator of the axial fan circulates the backflow portion of the flow in the air separator to rectify this circulation flow and merge it with the flow on the upstream side, the circulation in the air separator is Whether the performance is good or bad affects the effect of delaying the stall of the axial fan and improving the characteristics. Therefore, in order to further improve the characteristics of the axial flow fan, it is necessary to improve the circulation property in the air separator. However, as shown in FIG. 1, this air separator has the front wall 10 and the rear wall 10 of the outer wall 4 of the air separator. Each wall 11 is provided so as to be inclined toward the upstream side to form a cavity.

By inclining the front wall 10 of the outer wall 4 in this way, the backflow portion of the flow indicated by the arrow 8 generated at a part of the tip 3 of the rotor blade 2 is uniformly distributed to the air flow vanes 7 in the air separator. Inflow becomes easier, pressure loss in the air separator is reduced, and circulation is improved. In addition, by inclining the rear wall 11 of the outer wall 4 in this way, the circulation flow passing through the rectifying vanes 7 is guided so as to flow along the rear wall 11, and a velocity component in the same direction as the upstream flow is generated. It is given and becomes easy to join the flow on the upstream side, the pressure loss in the air separator is reduced, and the circulation is improved. Fig. 2 is a characteristic curve diagram of an axial flow fan, and the dotted line shows the characteristic curve when this air separator is provided. Compared to the stall point A when the air separator shown by the solid line is not provided (Solid wall), the stall point B when the conventional air separator is provided is considerably improved, but when this air separator is provided At the stall point C in Fig. 2, the flow rate is almost zero, and the effect of delaying the stall of the axial fan and improving the characteristics of the axial fan is extremely large. It is considered that such an effect is mainly due to the inclination of the front wall 10 of the outer wall 4 of the air separator.

[0014]

[Effect of the device]

 Since the air separator of the axial fan according to the present invention is configured as described above, the pressure loss in the air separator is reduced and the circulation is improved, so that the stall of the axial fan is delayed. The characteristics of the axial fan are improved.

[Brief description of drawings]

FIG. 1A is a sectional view of an air separator of an axial fan according to an embodiment of the present invention, and FIG. 1B is a drawing of FIG. 1A.
It is a bb sectional view in.

FIG. 2 is an explanatory view of its operation.

3A is a sectional view of an air separator of a conventional axial flow fan, and FIG. 3B is a sectional view taken along line bb in FIG. 3A.

FIG. 4 is an explanatory view of its operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotor 2 moving blade 3 tip of moving blade 4 outer wall 5 inner wall 6 casing 7 straightening vane 10 front wall of air separator 11 rear wall of air separator

Claims (2)

[Scope of utility model registration request] 1. A plurality of rectifying vanes, which are annularly provided on the outer periphery of the casing, have an inlet facing the upstream end of the moving blade, and have an outlet opening on the upstream side to rectify the flow in the axial direction inside. An air separator for an axial fan, wherein an inlet side wall of an outer wall is provided so as to be inclined toward an upstream side. 2. The air separator for an axial fan according to claim 1, wherein the outlet side wall of the outer wall is provided so as to be inclined toward the upstream side.