JP2000328906A - Axial turbine - Google Patents

Abstract

(57) Abstract: A diffuser for an axial turbine capable of removing an inflow swirling component without increasing loss. SOLUTION: In a diffuser of an axial flow turbine 1 formed on a downstream side of a moving blade 4, a blunt guide blade 10 is provided in a diffuser passage 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial flow turbine diffuser.

[0002]

2. Description of the Related Art As shown in FIG. 4, an axial turbine 22 having an annular diffuser 21 on the downstream side of a rotor blade 20 comprises:
Since the rotor blades 20 rotate, the gas fluid easily flows into the diffuser 21 at various angles, and a swirling flow is easily generated in the diffuser 21.

When a swirling flow occurs in the diffuser 21, separation (backflow) occurs on the inner wall surface 23 and the outer wall surface 24 near the outlet of the diffuser 21, and the loss increases sharply.

In order to remove such a swirl component, as shown in FIG.
5 is also considered.

The guide wings 25 are made of a plate having a uniform thickness, extend radially in the vicinity of the entrance of the diffuser passage 26, and partition the entrance of the diffuser 21 in the circumferential direction. The guide blade 25 is formed to have a predetermined length in the axial direction, and guides the swirling flow to the blade surface 27 in the axial direction.

[0006]

However, when the guide vane 25 is provided in the diffuser 21, if the angle of the guide vane 25 and the inflow angle of the gas fluid are different, the guide vane 25 hinders a smooth flow. There is a problem that the loss is increased.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a diffuser for an axial turbine which can remove an inflow swirling component without increasing a loss.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an axial flow turbine diffuser formed downstream of a moving blade, wherein a blunt guide vane is provided in a diffuser passage. It is.

Further, it is preferable that the guide vanes are provided so as to extend radially in a radial direction.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, an axial turbine 1 includes a first flow path 3 formed in parallel with a rotary shaft 2 and a gas fluid such as air provided in the first flow path 3. The rotating blades 4 rotate the rotating shaft 2 in response to the rotating blades 2, and an annular diffuser 5 is formed downstream of the rotating blades 4.

The first flow path 3 is formed in an annular shape on the outer peripheral side of the rotating shaft 2. A stationary blade 7 for adjusting the flow of the gas fluid is provided near the outlet 6 of the first flow path 3 facing the moving blade 4.

The annular diffuser 5 is formed in an annular shape so as to be smoothly connected to the first flow path 3 via the moving blades 4, and has a wrapper at the outlet side so as to allow the gas fluid to flow radially outward. It is formed to open in a shape. Annular diffuser 5
The pipe 8 is connected to the outlet side of the pipe.

The diffuser passage 9 is provided with a plurality of blunt guide vanes 10. Here the blunt shape is
As shown in FIG. 3, in the cross-sectional shape of the guide vane 10, the front end 11 located on the upstream side is largely rounded and indicates a streamline shape narrowing toward the rear end side.

By rounding the tip 11 of the guide vane 10 greatly, the resistance to oblique flow is reduced as compared with the conventional guide vane having a sharpened tip, and the generation of a vortex around the tip 11 is prevented. To smoothly change the swirling flow into an axial flow, and guide the swirling flow into the annular diffuser 5.

As shown in FIG. 1 and FIG.
Are radially extended in the radial direction so as to connect the inner wall 12 and the outer wall 13 of the annular diffuser 5. The inter-blade flow path 14 formed between the guide vanes 10, 10 is formed so as to continuously expand toward the downstream side by the guide vane 10 narrowing rearward. A diffuser is formed.

Next, the operation will be described.

The axial flow reaching the moving blade 4 via the first flow path 3 rotates the moving blade 4 and changes its direction in the turning direction under the influence of the moving blade 4. At this time, the swirling angle of the swirling flow generated by the rotating blade 4 being rotated is not constant but changes its direction to various angles.

The swirling flow generated under the influence of the moving blade 4 first strikes the tip 11 of the guide blade 10 located downstream of the moving blade 4.

Since the tip 11 is formed in a large round shape, the resistance is small even if the tip 11 is hit from any angle, and a vortex is not generated near the tip like a sharp plate.
The loss due to the resistance of the wing itself can be prevented.

The swirling flow impinging on the tip 11 is guided by the guide vanes 1
While the flow direction is changed in the axial direction along 0, the flow velocity is reduced by the diffuser effect of the inter-blade flow path 14 surrounded by the streamlined guide vanes 10 narrowing toward the rear end side, and the gas fluid Pressure is increased.

The swirling flow is guided by the guide vanes 10 and becomes an axial flow, so that the swirling flow can be prevented from flowing into the annular diffuser 5. Accordingly, it is possible to prevent the separation between the inner wall 12 and the outer wall 13 near the outlet of the annular diffuser 5.

Thereafter, the axial flow flows into the annular diffuser 5, where the flow velocity is further reduced, and the pressure of the gas fluid is increased.

At this time, since the downstream end side of the moving blade 4 has a negative pressure, the moving blade 4 can be efficiently rotated.

As described above, since the blunt guide vanes 10 are provided in the diffuser passage 9, losses due to the resistance of the guide vanes 10 themselves can be prevented, and the inflow swirling component can be removed without increasing the losses. Can be.

Further, since the guide vanes 10 are provided to extend radially in the radial direction, the inflow swirling component can be efficiently removed.

The diffuser effect of the inter-blade flow path 14 between the guide vanes 10 can be easily increased with a simple structure, and the efficiency of the annular diffuser 5 can be increased.

[0028]

In summary, according to the present invention, the following excellent effects can be obtained.

(1) The inflow swirling component can be removed without increasing the loss.

(2) The efficiency of the diffuser can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a diffuser of an axial turbine showing a preferred embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a side sectional view of a diffuser of a conventional axial flow turbine.

FIG. 5 is a side sectional view of a diffuser of a conventional axial flow turbine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Axial flow turbine 4 Moving blade 5 Annular diffuser (diffuser) 9 Diffuser passage 10 Guide vane

Claims (2)

[Claims] 1. A diffuser for an axial flow turbine formed on a downstream side of a moving blade, wherein a blunt guide vane is provided in a diffuser passage. 2. The diffuser according to claim 1, wherein the guide vanes are provided to extend radially in a radial direction.