JP3528285B2 - Axial blower - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-stage or multi-stage axial blower having a wide distance between stages.

[0002]

2. Description of the Related Art Generally, an axial flow fan is constructed based on a combination of a rotating annular blade row and a stationary annular blade row, and in the case of a model with a large pressure rise, a large number of combinations are arranged in series, and a so-called multistage To do.

First, the case of a rotary annular blade row will be described. When the flow flows through the inner casing and the outer casing flow passage, as shown in FIG. 19, due to friction with the wall surface,
The flow near the wall loses kinetic energy. Therefore, the flow velocity of the flow flowing into the rotating annular blade row is smaller in the vicinity of the inner and outer wall surfaces than in the intermediate portion separated from the wall surface. The substantial cross-sectional area of the flow channel decreases due to the existence of a layer having a low flow velocity, a so-called boundary layer. The decrease in the actual cross-sectional area is called a blockage, and usually reaches several percent. It is rare that the actual inflow distribution is known at the time of blade design. Therefore, the blade is designed assuming a uniform inflow flow parallel to the rotation axis of the rotating annular blade row. At this time, if the blade height is determined by ignoring the blockage, the flow velocity in the central portion of the blade becomes larger than the design value, and the design pressure rise cannot be achieved. For this reason, a design method is widely used in which the blade is raised by the amount of the blockage and the central portion of the blade realizes a flow in a designed state to obtain a predetermined pressure rise. In this method, near the inner and outer wall surfaces, the blades are configured for a uniform inflow flow parallel to the rotation axis of the rotating annular blade row. The inlet portion of the blade directs the incoming flow relative to the blade. Since the axial velocity of the actual inflow flow near the inner and outer wall surfaces is significantly smaller than that of the uniform inflow flow, the actual inflow flow collides strongly with the blade designed in this way, resulting in a large loss. There was a problem. A similar problem exists for the blades that make up the stationary annular cascade.

To solve this problem, N. A. Cumsty
(NA Kampshii) by Aerodynamic
s of Compressors (Aerodynamics of Compressors) pp. 353-355, the vane profile of the vanes is strengthened near the inner and outer wall surfaces to match the shape of the blade inlet with the actual inflow angle. An example of efficiency improvement in a six-stage axial compressor using the method is shown. Further, in Japanese Patent Application Laid-Open No. 62-195495, as shown in FIGS. 20 and 21, the warp angle of the airfoil is increased near the inner and outer wall surfaces of the moving blade and the stationary blade (θa> θo), and βo>.
A method is shown in which the shape of the blade entrance is adjusted to the angle of the actual inflow flow so as to be βa, and the pressure rise is not reduced. If the shape of the blade inlet is adjusted to the angle of the actual inflow without increasing the warp angle of the airfoil, the angle on the outlet side of the blade will approach the circumferential direction of rotation, and the pressure rise of the flow passing through the blade will decrease. This is because.

These methods improve the so-called collision loss based on the fact that the flow direction does not smoothly flow into the airfoil at the blade inlet portions near the inner and outer wall surfaces of the vane, but the airfoil warpage is improved. The secondary flow becomes strong to increase the loss, and an increase in loss due to the secondary flow cannot be avoided. However, the strengthening of the secondary flow promotes the mixing of the flow near the inner and outer wall surfaces and the flow in the part away from the wall surfaces, so in the case of a multi-stage compressor, it flows into the stationary blades installed downstream of the rotor blades. The boundary layer near the inner and outer walls of the flowing flow becomes thinner. Due to this effect, the efficiency of the moving blade is improved, and in addition to reducing the collision loss of the moving blade and the stationary blade, as a compressor, the increase in the loss due to the secondary flow of the moving blade and the stationary blade compensates for the excessive efficiency improvement. Will be realized. These methods are effective in a multi-stage axial compressor, which has a large effect of promoting the mixing of the flow near the inner and outer wall surfaces and the flow in the portion away from the wall surfaces. But,
Most of the axial flow blowers are a single-stage type composed of a set of rotating blades and a stationary blade row, or a multi-stage type having a wide interval between stages. Since there is no next stage in the single-stage model, there is no effect of improving the efficiency of the next stage by promoting the mixing of the flow near the inner and outer wall surfaces and the flow in the part away from the wall. For models with wide gaps between stages, the flow near the inner and outer wall surfaces and the flow away from the wall easily mix from the outlet of the previous stage to the inlet of the next stage. By 2
The increase in loss due to the next flow and the decrease in collision loss offset each other,
The efficiency improvement is reduced.

As shown in FIG. 22, when the blades are inclined so that the leading edges are not separated from the plane including the leading edges of the plurality of blades forming the blade row, the suction surface side is the side wall at one of the blade tips. An acute angle is formed, and at the other blade tip, the suction surface side forms an obtuse angle with the side wall. The loss due to the secondary flow increases at the blade tip where the suction surface side forms an acute angle with the side wall, and the loss due to the secondary flow decreases at the blade tip where the suction surface side forms an obtuse angle with the side wall.
J. Robinson (C.J.Robinson) and 2 others "Measurement and Calcu"
lation of the Three-Dimen
regional Flow in Axial Comp
restress stators, with and
Without End-Bends, ASME PA
per 89-GT-6 (Measurement and Calculation of the Three Dimensional Flow In Axial Compressor Statuses, With and Without End Bends, EYME PAY 89-G-Tee
6) ”. However, when both blade tips are inclined, it becomes difficult to fix the blade tips to the side wall surface, especially when fixing the hollow blade by welding. large.

An example in which the blades of an axial blower are tilted in a plane perpendicular to the rotation axis in order to reduce noise is disclosed in JP-A-52-34.
No. 409 and Japanese Patent Application Laid-Open No. 52-62712. JP-A-52-34409 aims at reducing the interference noise by intersecting the leading edge of the stationary blade with the trailing edge of the moving blade. In many cases, the trailing edge of the blade is almost perpendicular (radial) to the axis of rotation, resulting in tilting of the vane. Therefore, there is no concept that the angle formed between the suction surface of the stationary blade and the inner and outer side wall surfaces is not an acute angle. In the embodiment of Japanese Patent Laid-Open No. 52-34409, since the direction of rotation is not shown, it cannot be determined which surface of the vane is the suction surface. The angle formed by one of the inner and outer side wall surfaces is an acute angle. In the embodiment, the inner peripheral end of the stationary blade has a shape in which a cylindrical side wall surface does not exist, but since this shape is not general and is significantly different from the shape targeted by the present invention, a cylindrical shape is formed on the inner peripheral side. A shape having a side wall surface is assumed as a known example.

In the case of JP-A-52-62712,
It is clarified that the inner circumferential side of the vane is inclined in the rotation direction. In this case, the angle between the outer wall surface and the suction surface of the vane becomes an acute angle, and the loss due to the secondary flow cannot be reduced.

Japanese Unexamined Patent Publication (Kokai) No. 57-186097 discloses a method of reducing the noise and improving the efficiency by bending the tip side of the stationary blade downstream of the moving blade in the rotating direction of the moving blade. However, it is intended for an axial blower with a structure that does not have an outer cylinder that houses the stationary blades on the downstream side.There is a loss due to the tip vortex flowing out from the tip side of the stationary blade, but the stationary blade and the outer cylindrical surface Since the flow path surrounded by is not formed, there is no secondary flow loss. Therefore, the stationary blade whose tip side is curved in the rotating direction of the moving blade has no effect of reducing the secondary flow loss.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce loss due to secondary flow and to improve efficiency in the case of a single stage composed of a rotor blade row and a stationary blade row or a multi-stage having a wide step interval. It is to provide an axial-flow blower having.

[0011]

Means for Solving the Problems The above-mentioned object is to provide a blade constituting a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, and an outer peripheral side fixing the blade. And a casing for accommodating the rotating and rotating blade rows, and means for supporting and rotating the rotating and rotating blade rows, the stationary ring blade rows and the rotating and rotating blade rows. In a blower, the angle formed by the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface whose axis is the rotation axis of the rotating annular blade row is developed into a plane. Is defined as the warp angle, the rotating annular blade row or the stationary annular blade row is constituted by a blade whose warp angle is maximum between the inner wall side and the outer wall side. To be achieved.

[0012] Further, the above-mentioned object is that the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface having the axis of rotation of the rotary toroidal blade row as the axis is developed into a plane. When the angle formed is defined as a warp angle, the blade angle of the blade of the rotating annular blade row or the stationary annular blade row is composed of the blade having the maximum in the middle between the wall surface on the inner peripheral side and the wall surface on the outer peripheral side. , A straight line connecting the leading edge and the trailing edge of the airfoil when the airfoil appearing on the cylindrical surface with the axis of rotation of this rotating annular blade row as an axis is developed on a plane, and the blade row appearing on the cylindrical surface When the angle formed by the line connecting the leading edges and the line intersecting at right angles is defined as the stagger angle, the stagger angle decreases from the inner peripheral side to the outer peripheral side in the stationary annular blade row. A value obtained by twice differentiating the stagger angle by the distance from the inner peripheral side to the outer peripheral side, which is formed by a portion and a constant portion. When the rate of change is defined, the rate of change is positive, or the stagger angle of the blade is constant in the rotating annular blade row where the stagger angle increases from the inner circumference side to the outer circumference side. Formed with and the rate of change is positive,
To be achieved.

Further, the above object is to provide a line connecting each of the leading edge, the trailing edge, or the center of gravity of the airfoil in the cylindrical cross section, which constitutes the stationary annular blade row installed downstream of the rotating annular blade row. One of them is achieved by the fact that it is perpendicular (radial) to the rotation axis of the rotary annular blade row near the inner wall surface and inclined in the rotation direction near the outer wall surface.

Further, the above object is to provide a line connecting each of a leading edge, a trailing edge or a center of gravity of an airfoil in a cylindrical cross section, which constitutes a stationary annular blade row installed downstream of the rotating annular blade row. Any or all of these are at right angles (radial) to the rotation axis of the rotating annular blade row in the vicinity of the wall surface on the inner peripheral side,
A straight line that connects the leading edge and the trailing edge of the airfoil when it is developed on a plane that is inclined in the direction of rotation near the outer wall and that appears on a cylindrical surface whose axis is the axis of rotation of this rotating annular blade row. And the stagger angle of the wing is formed by a part where the stagger angle decreases from the root of the wing toward the tip and a part where the stagger angle is constant, and the rate of change is positive, or the stagger angle is from the inner peripheral side. This is achieved by forming the stagger angle toward the outer peripheral side and the constant portion to form a constant rate of change.

[0015]

When the warp angle of the rotary annular blade row is set to be large in the middle of the inner and outer wall surfaces and small in the vicinity of the wall surface, the efficiency is improved by the following operation.

The first is the reduction of loss due to the secondary flow.
The loss due to the secondary flow tends to increase as the boundary layer on the inner and outer peripheral wall surfaces of the blade row inlet becomes thicker and as the airfoil warp angle increases. By reducing the warp angle near the inner and outer wall surfaces, the secondary flow loss due to the boundary layer of the inner and outer wall surfaces of the blade row inlet is reduced.

The second is to improve efficiency by distributing the work in the blade height direction. The pressure loss that occurs in the middle portion of the inner and outer peripheral walls of the blade row is only the loss that occurs due to the friction between the blade surface and the flow, and is small. Therefore, mechanical energy can be transmitted to the flow with high efficiency in the middle of the inner and outer walls. On the other hand, near the inner and outer wall surfaces, in addition to the loss caused by the friction between the blade surface and the flow, a secondary flow occurs due to the interference with the inner and outer wall surfaces, and the loss is large, so the efficiency of transmitting mechanical energy to the flow is Drastically reduced. If the warp angle is large in the middle of the inner and outer walls and small near the wall, the work (or power) of the part that can give work to the flow with high efficiency is large, and the part that gives work to the flow has low efficiency. Since the work amount (or power) of is small, the power as a whole is efficiently transmitted to the flow.

Since the warp angle in the vicinity of the wall surface on the outer peripheral side is minimized, the load on the blade at the outer peripheral edge of the blade is small, so the pressure difference between the pressure surface and the suction surface is small, and the gap between the outer peripheral edge of the blade and the wall surface is reduced. The leakage flow rate passing through is reduced, and the efficiency is improved by reducing the leakage flow rate. Also, since the peripheral speed of the blade near the outer wall is higher than that at the inner wall, if the warp angle of the airfoil is simply large in the middle of the inner and outer walls and small near the wall, The pressure at the stagnation point of the flow on the inner peripheral side becomes significantly lower than that on the outer peripheral side, and the mixing loss on the downstream side of the blade row increases. However, since the airfoil angle on the outer peripheral side is smaller than that on the inner peripheral side, the distribution of the pressure at the stagnation point is extremely low and the mixing loss on the downstream side of the blade row does not increase.

In the case of the stationary annular blade row which constitutes the axial blower, if the warp angle is set to be large in the middle of the inner and outer wall surfaces and small near the wall surface, the efficiency is improved by the action of reducing the loss due to the secondary flow. .

In both cases of the rotating annular blade row and the stationary annular blade row, if the warp angle of the airfoil is maximized in the middle between the wall surface on the inner peripheral side and the wall surface on the outer peripheral side, the maximum value of the warp angle is obtained. Is not much different from the inner wall surface or the outer wall surface, it is difficult to obtain the effect of improving efficiency. In the case of a rotating annular blade row, the blade is configured so that the stagger angle changes from the root to the tip of the blade in combination with an increase and a constant value, and the rate of change is positive. In the case of rows, the stagger angle decreases from the inner circumference side to the outer circumference side and changes with a combination of constant values,
In addition, if the blade is configured so that the rate of change is positive, it is possible to determine that the maximum value of the warp angle is not too small.

Further, the warp angle is maximum between the inner wall surface and the outer wall surface, and the warp angle of the blade near the outer wall surface is smaller than that near the inner wall surface. Since the load near the wall surface on the outer peripheral side of the blade is reduced by configuring above, it is not necessary to increase the chord length of the blade to increase the blade area in order to reduce the loss on the tip side. Therefore, it is possible to improve the efficiency of the axial blower and at the same time reduce the chord length of the blade from the inner circumference side to the outer circumference side monotonously.
The blades can be configured to withstand the centrifugal forces of high speed rotation without the use of special materials such as titanium.

Either the leading edge, the trailing edge of the blades forming the stationary annular blade row, or the line connecting the centers of gravity of the stationary blades in the cylindrical cross section, or a combination thereof, is used near the inner wall surface or On one side near the outer wall surface, it is perpendicular (radial) to the rotation axis of the rotating annular blade row, and on the other side, it is inclined in the rotation direction so that the suction surface side forms an obtuse angle with the side wall at the blade tip. If so, the loss due to the secondary flow is reduced at the blade tip inclined in the rotation direction. At the other tip, either the leading edge, the trailing edge of the blade, or the line connecting the centers of gravity of the stationary blades in the cylindrical cross section, is located near the inner wall surface or the outer wall surface. Since it is perpendicular (radial) to the rotation axis of, the positioning work when fixing the blade tip to the side wall surface becomes easy, and particularly the effect of fixing the hollow blade by welding is great.

Further, the warp angle of the blades forming the stationary annular blade row is set to be large in the middle of the inner and outer wall surfaces and small in the vicinity of the wall surfaces, and preferably the stagger angle decreases from the inner peripheral side to the outer peripheral side. If the blade is configured so that it has a combination of constant values and the rate of change is positive, the loss due to the secondary flow is reduced. Either the leading edge, the trailing edge of the blade, or the line connecting the centers of gravity of the stationary blades in the cylindrical cross section, or a combination of these, is installed in the rotating annular blade row near either the inner wall surface or the outer wall surface. If it is configured so that the suction surface side forms an obtuse angle with the side wall at the blade tip, it is 2 The loss due to the secondary flow is further reduced. At the other tip, either the leading edge, the trailing edge of the blade, or the line connecting the centers of gravity of the stationary blades in the cylindrical cross section, is located near the inner wall surface or the outer wall surface. Since it is perpendicular (radial) to the rotation axis of, the positioning work when fixing the blade tip to the side wall surface becomes easy, and particularly the effect of fixing the hollow blade by welding is great.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a longitudinal sectional view of a two-stage axial flow fan, which is basically constructed by a combination of a rotating annular blade row and a stationary annular blade row. A plurality of moving blades 1 are attached to the outer circumference of the rotating body 2 in an annular shape to form a rotating annular blade row. The external shape (solid line) of the moving blade 1 is shown in FIG. The stationary blades 3 are fixed to either one or both of the inner casing 4 and the outer casing 5 to form a stationary annular blade row. The gas flow 6 flows through a flow path composed of the outer circumference, the inner circumference of the casing 4, and the outer circumference of the rotor 2, and is given kinetic energy while passing through the rotating annular blade row. With that, the pressure increases. Moreover, a part of the kinetic energy of the flow is converted into pressure while passing through the stationary annular blade row, and the pressure further increases. The broken line in FIG. 2 shows the blade in the case of assuming a flow distribution called a free vortex shape which is widely used in the past for comparison.

FIG. 3 is a diagram showing the distribution of the warp angle of the airfoil in the height direction of the blade 1. The warp angle of the airfoil is at the root (inner circumference) near the wall surface of the casing 4 and at the tip (outer circumference). The maximum warp angle is near the wall surface of the casing 5, and the warp angle near the wall surface of the casing 5 is smaller than the warp angle near the wall surface of the casing 4. The broken line in FIG. 4 shows the distribution when a flow distribution called a free vortex shape, which is widely used conventionally, is assumed for comparison.

The loss due to the secondary flow tends to increase as the boundary layer on the inner and outer peripheral wall surfaces of the blade row inlet becomes thicker and as the airfoil warp angle increases. By reducing the warp angle near the inner and outer wall surfaces, the secondary flow loss due to the boundary layer of the inner and outer wall surfaces of the blade row inlet is reduced. In the case of the rotor blade 1, the warp angle is large in the middle of the inner and outer peripheral wall surfaces and small in the vicinity of the wall surfaces, so that reducing secondary flow loss has the effect of doubly improving efficiency. The reason why the efficiency is improved will be described with reference to FIGS. FIG. 4 shows a distribution of the efficiency with which the moving blade 1 transfers mechanical energy to the flow when the flow passes through the rotary annular blade row composed of the moving blade 1. The broken line in FIG. 4 shows a case of a flow distribution called a free vortex shape which is widely used in the past for comparison. Since the loss generated in the middle part of the inner and outer walls is only the loss caused by the friction between the blade surface and the flow, the efficiency is high. Since the increase of the warp angle is several degrees or less compared to the case of the conventional free vortex type, the loss generated in the middle part of the inner and outer peripheral walls is almost the same as that of the free vortex type, so the efficiency is almost the same. On the other hand, near the inner and outer peripheral wall surfaces, in addition to the loss caused by the friction between the blade surface and the flow, a secondary flow occurs due to the interference with the inner and outer peripheral wall surfaces, and the loss is large, so the efficiency decreases. However, when the warp angle is set to be large in the middle of the inner and outer wall surfaces and small near the wall surface, the loss due to the secondary flow is reduced, so that the efficiency of transmitting mechanical energy to the flow is improved.

FIG. 5 shows the distribution of the product of the work amount and the flow rate received by the flow when the flow passes through the rotary annular blade row constituted by the moving blades 1. The amount of work received by the flow is the difference between the velocity component in the rotational direction of the flow before and after the rotating annular blade row seen from the stationary system and the blade 1.
Is the product of the circumferential velocities, and when the circumferential velocities are the same, the larger the warp angle, the greater the flow as long as the flow is along the blade surface. Since the flow rate has the same tendency, these products also have the same tendency. The broken line in FIG. 5 shows the distribution assuming a flow distribution called a free vortex shape which is widely used in the past for comparison. In the free vortex type, both work and flow have a constant distribution from the inner circumference to the outer circumference.
The area under the solid line and the area under the broken line are the same, that is, the total input work for the flow is the same. The mechanical energy received by the flow from the rotor blade 1 is the efficiency distribution shown in FIG. 4 multiplied by the weight of the product of the work amount and the flow rate shown in FIG. 5 and integrated from the inner circumference to the outer circumference. Therefore, even if the efficiency is the same, the solid line increases the mechanical energy received from the moving blade 1 by the flow. In addition to this, in the distribution of FIG. 4, the solid line is more efficient than the broken line (free vortex type) in the vicinity of the inner and outer circumferences due to the reduction of the secondary flow loss, and therefore the mechanical energy that the flow receives from the rotor blade 1 Grows larger. Since the total input work for the flow is the same, the efficiency is higher as the mechanical energy received from the rotor blade 1 is larger.

In the moving blade 1, when the warp angle near the outer peripheral wall surface is smaller than the warp angle near the inner peripheral wall surface, the following effects are obtained.

Since the amount of work at the outer peripheral end of the moving blade 1 is small, the pressure difference between the pressure surface and the negative pressure surface is small, the leakage flow rate passing through the gap between the outer peripheral end of the moving blade 1 and the wall surface is reduced, and the leakage flow rate is reduced. The efficiency can be improved by Since the blade peripheral speed near the outer wall is higher than that at the inner wall, if the warp angle of the airfoil is simply large in the middle of the inner and outer walls and small near the wall, The stagnation pressure of the flow on the circumferential side becomes significantly lower than that on the outer circumferential side, and the mixing loss on the downstream side of the blade row increases. However, since the airfoil angle on the outer peripheral side is smaller than that on the inner peripheral side, the distribution of the pressure at the stagnation point is extremely low and the mixing loss on the downstream side of the blade row does not increase.

A second embodiment of the present invention is shown in FIGS. 6 to 8. The stationary blade 3 shown by the solid line in FIG. 6 is a blade forming a stationary annular blade row. For comparison, the broken line in FIG. 6 shows a stationary blade that is widely used in the past and is assumed to have a flow distribution called a free vortex shape. FIG. 7 is a diagram showing the distribution of the warp angle of the airfoil in the height direction of the stationary blade 3, in which the warp angle of the airfoil is maximized in the middle between the wall surface on the inner peripheral side and the wall surface on the outer peripheral side. is there. The broken line in FIG. 7 shows the distribution when a flow distribution called a free vortex shape, which is widely used for comparison, is assumed. FIG. 8 shows a distribution of losses when a flow passes through a stationary annular blade row constituted by the stationary blades 3. The broken line in FIG. 8 shows the distribution when a flow distribution called a free vortex shape, which is widely used for comparison, is assumed. The loss generated in the middle portion of the inner and outer walls is only the loss caused by the friction between the blade surface and the flow, and is small. As compared with the free vortex type, the increase in the warp angle is several degrees or less, so the loss generated in the middle part of the inner and outer walls is not much different from the free vortex type. In the vicinity of the inner and outer wall surfaces, in addition to the loss caused by friction between the blade surface and the flow, there is interference due to the inner and outer wall surfaces.
The secondary flow is generated, and the loss is large, but the warpage angle near the inner and outer peripheral wall surfaces is small, so the loss due to the secondary flow is also small. The stationary annular blade row consisting of the stationary blades 3 of this shape is provided on the downstream side of the rotating annular blade row consisting of the moving blades 1 shown in FIG. If the warp angle is large, the effect is great.

FIGS. 9, 10 and 11 are views showing the relationship between the blade and the stagger angle in the above-mentioned first and second embodiments.

Generally, the tangent line of the blade leading edge of the airfoil warp line is approximately matched with the direction of the flow entering the blade at the design flow rate. Therefore, the blade shape is almost determined by the warp angle distribution in the blade height direction and the chord length distribution in the blade height direction. In both rotating and stationary circular blade cascades, when maximizing the warp angle of the airfoil midway between the wall surface on the inner circumference side and the wall surface on the outer circumference side, the maximum value of the warp angle is the inner circumference. It is difficult to obtain the effect of improving efficiency unless there is a large difference with the vicinity of the wall surface on the side or the vicinity of the wall surface on the outer peripheral side.
As shown in FIG. 9, a straight line connecting the leading edge and the trailing edge of the airfoil when the airfoil appearing on the cylindrical surface having the axis of rotation of the rotating annular blade row as an axis is developed on a plane, and appears on the cylindrical surface. When the angle formed by the line that intersects the line connecting the leading edges of the blade rows at a right angle is defined as the stagger angle, in the case of a rotating annular blade row, from the inner peripheral side (the root of the blade) as shown in FIG. When the stagger angle changes toward the outer peripheral side (tip) in combination with an increase and a fixed value, and the value obtained by differentiating the stagger angle twice from the inner peripheral side to the outer peripheral side is defined as the rate of change, Configure the wings so that the rate of change is positive. Further, in the case of a stationary annular blade cascade, as shown in FIG. 11, the stagger angle is changed from the inner peripheral side to the outer peripheral side by a combination of a decrease and a constant value so that the change rate becomes positive. By configuring, it is possible to determine that the maximum value of the warp angle is not too small.

FIG. 12 shows the chord length distribution of the third embodiment of a high speed rotating multistage axial blower in which the pressure rise per stage is large. Configure the blade so that the warp angle is maximum between the inner wall surface and outer wall surface, and the warp angle near the outer wall surface is smaller than that near the inner wall surface. As a result, the load near the wall surface on the outer peripheral side of the blade is reduced. Therefore, in order to improve the efficiency of the axial blower, it is not necessary to increase the chord length of the blade on the outer peripheral side to increase the blade area and reduce the load. Therefore, while maintaining high efficiency, the chord length of the blade can be monotonically decreased from the root (inner peripheral side) to the tip (outer peripheral side), as shown in FIG. The blade can be configured to withstand centrifugal force of high efficiency and high speed rotation without using special materials such as titanium.

FIG. 13 and FIG. 14 are respectively the fourth and fifth aspects of the present invention.
FIG. 11 is a diagram showing a fifth embodiment, which is an example of further improving the efficiency of the axial fan by further reducing the loss due to the secondary flow of the stationary annular blade row. FIG. 13 shows either the leading edge, the trailing edge or the line connecting the centers of gravity of the stationary blades 3 in the cylindrical cross section, the leading edge or the trailing edge of the stationary blades 3 constituting the stationary annular blade row installed on the downstream side of the rotating annular blade row. Alternatively, the combination of these is such that near the inner wall surface, the direction is perpendicular to the rotation axis of the rotating annular blade row, and near the outer wall surface, the direction of rotation is inclined so that the inner wall surface In the radial direction with respect to the rotation axis of the rotating annular blade row,
The outer peripheral side is inclined in the rotation direction. Therefore, at the blade tip on the outer peripheral side, the suction surface side forms an obtuse angle with the side wall, and the loss due to the secondary flow is reduced. The solid line in FIG. 15 shows the loss distribution of the embodiment of the present invention in which the tip side of the stationary blade 3 shown by the solid line in FIG. 13 is inclined, and the broken line in FIG.
The loss distribution when the stationary blade shown by the broken line 3 is not inclined is shown. The loss due to the secondary flow due to the effect of inclining the stationary blade 3 is reduced, and thus the loss on the outer peripheral side is reduced. In addition, since the stationary blade 3 is perpendicular (radial) to the rotation axis of the rotating annular blade row in the vicinity of the wall surface on the inner peripheral side, the wall surface on the inner peripheral side can be used as a reference at the time of assembly, so that a special treatment is required. It becomes possible to fix the stationary blade 3 to the wall surface without using any tool. In particular, the effect of fixing the hollow blade by welding is great.

In FIG. 14, the outer peripheral side wall surface of the stationary blade 3 is perpendicular to the rotation axis of the rotary annular blade row, and the inner peripheral side wall surface is inclined in the rotation direction. In this case, the loss due to the secondary flow near the wall surface on the inner peripheral side is reduced, and the effect of facilitating the assembly when fixing the stationary blade 3 utilizing the outer peripheral side is large.
The solid line in FIG. 16 shows the loss distribution of the embodiment of the present invention in which the inner peripheral side of the stationary blade 3 shown by the solid line in FIG. 14 is inclined, and the broken line in FIG. 16 is the stationary blade shown in broken line in FIG. The loss distribution in the case of not performing is shown. The loss due to the secondary flow due to the effect of inclining the stationary blade 3 is reduced, so that the loss on the inner peripheral side is reduced.

FIGS. 17 and 18 are sixth and seventh embodiments, respectively, in which the warp angle of the embodiment shown in FIGS. 13 and 14 is between the inner wall surface and the outer wall surface. It is configured to be maximum. The broken lines in FIGS. 17 and 18 indicate the examples of FIGS. 13 and 14 for comparison. Due to the effect of inclining the stationary blades 3 and the effect of reducing the blade load near the inner and outer peripheral wall surfaces, the loss due to the secondary flow is further reduced.

[0038]

According to the present invention, a secondary flow loss in a blade row can be reduced and a highly efficient axial blower can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of an axial flow fan according to the present invention.

FIG. 2 is an external shape diagram of a first embodiment of a moving blade in the axial blower shown in FIG.

3 is a diagram showing the distribution of the warp angle of the airfoil in the height direction of the moving blade in FIG.

FIG. 4 is a diagram showing a distribution of mechanical energy transfer efficiency when a gas flow passes through a rotary annular blade row of the rotor blade shown in FIG.

5 is a diagram showing a distribution of a product of a work amount and a flow amount received by the flow when the flow passes through the rotary annular blade row of the moving blade shown in FIG.

FIG. 6 is a view showing blades that form a stationary annular blade row according to a second embodiment of the present invention.

FIG. 7 is a diagram showing the distribution of the warp angle of the airfoil in the height direction of the stationary blade of the embodiment shown in FIG.

8 is a diagram showing a distribution of loss when a flow passes through the stationary annular blade row of the embodiment shown in FIG.

FIG. 9 is a diagram showing the definition of a stagger angle of a wing.

FIG. 10 is a diagram showing a stagger angle distribution of rotor blades of a rotary annular blade row.

FIG. 11 is a diagram showing a stagger angle distribution of a stationary blade of a stationary annular blade row.

FIG. 12 is a diagram showing a distribution of chord length in the height direction of the blade.

FIG. 13 is a view showing blades that constitute a stationary annular blade row according to a fourth embodiment of the present invention.

FIG. 14 is a view showing blades constituting a stationary annular blade row according to a fifth embodiment of the present invention.

15 is a diagram showing a distribution of loss when a flow passes through the stationary annular blade row of the embodiment shown in FIG.

16 is a diagram showing a distribution of loss when a flow passes through the stationary annular blade row of the embodiment shown in FIG.

FIG. 17 is a view showing a blade that constitutes a stationary annular blade row according to a sixth embodiment of the present invention.

FIG. 18 is a view showing a blade that constitutes a stationary annular blade row according to a sixth embodiment of the present invention.

FIG. 19 is a diagram showing a relationship between an axial flow velocity and a relative moving velocity of a moving blade between inner and outer casings.

FIG. 20 is a diagram showing a relationship between an axial flow velocity and a moving blade relative inflow velocity.

FIG. 21 is a diagram showing an inflow flow angle and a warp angle in a blade.

FIG. 22 is a diagram for explaining a flow loss in a blade.

[Explanation of symbols]

1 ... Moving blade 2 ... Rotating body 3 ... Shizuka 4 ... Inner peripheral casing 5 ... Outer casing 6 ... Flow 7 ... Suction casing 8 ... Diffuser

Continuation of the front page (56) Reference JP-A-62-195495 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04D 29/38

Claims (10)

(57) [Claims] 1. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. When defining the angle formed by the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface whose axis is the rotation axis of the cascade is expanded to a plane, An axial-flow blower, characterized in that the rotating annular blade row or the stationary annular blade row is constituted by blades having a maximum warp angle between an inner peripheral wall surface and an outer peripheral wall surface. 2. The axial flow fan according to claim 1, wherein the rotary annular blade row and the stationary annular blade row have maximum warpage angles in the middle between the inner peripheral wall surface and the outer peripheral wall surface. An axial-flow blower characterized by being configured by. 3. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. When defining the angle formed by the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface whose axis is the rotation axis of the cascade is expanded to a plane, A blade having the largest warp angle in the vicinity of the wall surface on the inner peripheral side and the wall surface on the outer peripheral side of the rotating annular blade row, and a cylindrical surface having the axis of rotation of the rotating annular blade row as an axis. A straight line connecting the leading edge and the trailing edge of the airfoil when the airfoil appearing above is expanded to a plane and the front of the blade row appearing on the cylindrical surface. When defining the angle formed by the line connecting the lines and the line intersecting at right angles as the stagger angle, the stagger angle of the blade is a part where the stagger angle increases from the inner peripheral side toward the outer peripheral side and the part that is constant. The axial flow blower is characterized in that the change rate is positive when a value obtained by differentiating the stagger angle from the inner circumference side to the outer circumference side twice is defined as the change rate. 4. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. When defining the angle formed by the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface whose axis is the rotation axis of the cascade is expanded to a plane, The warp angle of the blades of the rotating annular blade row is maximized in the middle between the vicinity of the inner wall surface and the outer wall surface, and the warp angle near the inner wall surface is larger than the warp angle near the outer wall surface. It is composed of blades, and the airfoil that appears on the cylindrical surface whose axis is the axis of rotation of this rotating annular blade row is expanded to a plane. When defining the angle formed by a straight line connecting the leading edge and the trailing edge of the airfoil and a line intersecting at right angles with the line connecting the leading edges of the blade rows appearing on the cylindrical surface, the blade is defined as The stagger angle is staggered from the inner side to the outer side.
When the rate of change is defined as the rate of change, which is formed by a portion where the angle increases and a portion where the angle is constant, and the stagger angle is differentiated twice by the distance from the inner circumference side to the outer circumference side, the change rate is positive. Axial blower. 5. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. When defining the angle formed by the tangent line at the leading edge and the tangent line at the trailing edge of the warp line of the airfoil when the airfoil appearing on the cylindrical surface whose axis is the rotation axis of the cascade is expanded to a plane, A cylindrical surface whose axis of rotation is the axis of rotation of the stationary annular ring blade row, which is formed by a blade having a maximum warp angle in the vicinity of a wall surface on the inner peripheral side and a wall surface on the outer peripheral side. A straight line connecting the leading edge and the trailing edge of the airfoil when the airfoil appearing above is expanded to a plane, and the leading edge of the blade cascade appearing on the cylindrical surface When the angle formed by the line that intersects with the line that intersects at a right angle is defined as the stagger angle, the stagger angle of the blade is a portion where the stagger angle decreases from the inner peripheral side toward the outer peripheral side and a constant portion. The axial flow blower is characterized in that the change rate is positive when a value obtained by differentiating the stagger angle twice from the inner circumference side to the outer circumference side is defined as the change rate. 6. The axial blower according to claim 4 or 5, characterized in that the chord length of the blades forming the rotating annular blade row monotonically decreases from the inner peripheral side to the outer peripheral side. Axial blower. 7. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. In the vicinity of the wall surface on the inner peripheral side, either the leading edge, the trailing edge of the blades forming the stationary annular blade row installed downstream of the blade row or the line connecting the center of gravity of the airfoil in the cylindrical cross section An axial blower, which is perpendicular to a rotation axis of the rotating annular blade row and is inclined in a rotation direction near a wall surface on an outer peripheral side. 8. The axial flow fan according to claim 7, wherein the center of gravity of the leading edge, trailing edge or airfoil shape of a blade forming a stationary annular blade row installed downstream of the rotating annular blade row. All of the lines connecting each of them are at right angles to the rotation axis of the rotary annular blade row near the wall surface on the inner peripheral side, and are inclined in the rotation direction near the wall surface on the outer peripheral side. Axial blower. 9. A blade forming a rotating annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotating annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. In the vicinity of the wall surface on the inner peripheral side, either the leading edge, the trailing edge of the blades forming the stationary annular blade row installed downstream of the blade row or the line connecting the center of gravity of the airfoil in the cylindrical cross section It is perpendicular to the rotation axis of the rotating annular blade row, is inclined in the rotation direction in the vicinity of the wall surface on the outer peripheral side, and has a plane shape that appears on a cylindrical surface whose axis is the rotation axis of this rotating annular blade row. The straight line connecting the leading edge and the trailing edge of the airfoil when it is deployed at a right angle to the line connecting the leading edges of the blade rows appearing on the cylindrical surface. When defining the angle formed by the vertical line as the stagger angle, the stagger angle of the blade is formed by a portion where the stagger angle decreases from the inner peripheral side to the outer peripheral side and a portion where the stagger angle is constant. An axial-flow blower characterized in that the rate of change is positive, when the value is defined as a value obtained by differentiating the angle twice from the distance from the inner peripheral side to the outer peripheral side. 10. A blade forming a rotary annular blade row, an inner peripheral wall fixing the blade, a stationary annular blade row, an outer peripheral wall fixing the blade, and the rotary annular ring. An axial-flow blower comprising: a means for supporting and rotating the blade row; and a casing for accommodating the rotating annular blade row, the stationary annular blade row, and the means for supporting and rotating the rotating annular blade row. All of the lines connecting the leading edge, the trailing edge, or the center of gravity of the airfoil in the cylindrical cross section, which forms the stationary annular blade row installed downstream of the blade row, are located near the wall surface at the root of the blade. It is perpendicular to the axis of rotation of the rotating annular blade row, tilts in the direction of rotation near the tip wall surface, and develops the airfoil that appears on the cylindrical surface with the axis of rotation of this rotating annular blade row as a plane. At a right angle to the line connecting the leading and trailing edges of the airfoil and the line connecting the leading edges of the blade rows appearing on the cylindrical surface. When the angle formed by a line is defined as a stagger angle, the stagger angle of the blade is formed by a portion where the stagger angle decreases from the root of the blade toward the tip and a portion where the stagger angle is constant, and the stagger angle is defined as follows. An axial-flow blower characterized in that the changing rate is positive when a value obtained by differentiating twice the distance from the root of the blade to the tip is defined as the changing rate.