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Turbo Machinery

a technology of rotating bodies and rotating bodies, which is applied in the direction of mechanical equipment, machines/engines, liquid fuel engines, etc., can solve the problems of reducing the vibrational stability of the rotor, unstable vibration of the rotor, etc., and achieves adequate sealing performance and suppressing unstable vibration of the rotating body

Inactive Publication Date: 2013-08-29
MITSUBISHI HITACHIPOWER SYST LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention relates to a device for reducing unstable vibration caused by fluid force during the rotation of a rotating body. The invention generates a pressure peak that suppresses the whirling motion of the rotating body and ensures proper sealing performance without adding any leakage flow structure to the labyrinth seal.

Problems solved by technology

When the above-described labyrinth seal is used, the downward leakage flow therein may cause unstable vibration of the rotor.
This may decrease the vibrational stability of the rotor to cause unstable vibration.

Method used

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Examples

Experimental program
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first embodiment

[0027]A first embodiment of the present invention will be described below with reference to FIGS. 1 to 5. The first embodiment is an example in which the present invention is applied to a labyrinth seal device for use in a steam turbine.

[0028]First of all, the structure of essential parts of the steam turbine to which the present invention is applied and the problem with a conventional labyrinth seal device will be described.

[0029]FIG. 1 is a cross-sectional view illustrating an exemplary structure of essential parts of a common steam turbine.

[0030]In the steam turbine 1 shown in FIG. 1, reference numeral 2 denotes a rotor, reference numeral 3 denotes a rotor casing, reference numeral 4 denotes a nozzle diaphragm inner ring, reference numeral 5 denotes a nozzle diaphragm outer ring, reference numeral 6 denotes a rotor blade, reference numeral 7 denotes a nozzle, reference numeral 8 denotes a diaphragm packing, reference numeral 9 denotes a tip seal, and reference numeral 10 denotes ...

second embodiment

[0053]A second embodiment of the present invention will now be described. FIG. 6 is an exemplary axial cross-sectional view illustrating the labyrinth seal device according to the second embodiment. Like elements in the first and second embodiments are designated by the same reference numerals and will not be redundantly described.

[0054]In the first embodiment, which has been described earlier, the high-pressure side seal fin 12 is long whereas the low-pressure side seal fin 14 is short. In the second embodiment, on the other hand, the seal fins have a predetermined (fixed) length, and both the rotor 2 and the seal ring 15 have fins. The seal fins for the rotor2 and the seal ring 15 are spaced at unequal intervals so that a seal fin 12a positioned at a high-pressure side of a stationary body agrees in axial position with a seal fin 12b positioned at a high-pressure side of a rotating body, and that low-pressure side seal fins 14 do not agree with each other in axial position. As the...

third embodiment

[0059]A third embodiment of the present invention will now be described. FIG. 7 is an exemplary axial cross-sectional view illustrating the labyrinth seal 11 according to the third embodiment. Like elements in the first and third embodiments are designated by the same reference numerals and will not be redundantly described.

[0060]In the first embodiment, which has been described earlier, the high-pressure side seal fins 12 have a relatively large gap to prevent the fins from rubbing on an opposing portion of the rotor due to the difference in radial thermal elongation between the rotor and the casing. In the third embodiment, on the other hand, the high-pressure side seal fins 12 are long, and an abradable layer 16 is formed on portions opposing the high-pressure side seal fins 12 to ensure that the high-pressure side seal fins 12 have a very small gap. Even when an upstream seal fin 12 rubs against the seal ring 15 due to the difference in radial thermal elongation between the roto...

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PUM

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Abstract

Turbo machinery includes a rotating body, a stator, and a labyrinth seal disposed in a gap between the rotating body and the stator. The labyrinth seal includes a first seal fin and a second seal fin both of which protrude from a portion of one of the rotating body and the stator toward an opposing portion of the other one of the rotating body and the stator. The first seal fin is disposed on the high-pressure side of the center of the labyrinth seal in the axial direction of the rotating body. The second seal fin is disposed on the low-pressure side of the first seal fin to form a cavity together with the first seal fin. A gap to the portion opposing the first seal fin is smaller than a gap to the portion opposing the second seal fin.

Description

TECHNICAL FIELD[0001]The present invention relates to turbo machinery, and more particularly to high- speed, high-pressure turbo machinery such as a steam turbine.CLAIM OF PRIORITY[0002]The present application claims priority from Japanese Patent application serial No. 2012-42693, filed on Feb. 29, 2012, the content of which is hereby incorporated by reference into this application.BACKGROUND ART [0003]In the turbo machinery such as a steam turbine, a labyrinth seal is of ten disposed between a rotor (rotating shaft) and a casing in order to prevent working fluid in the casing, which houses the rotor, from leaking along the rotor.[0004]The labyrinth seal generally includes a plurality of seal fins, which are disposed along the axial direction of the rotor. A pressure drop void is formed between fins along the outer circumference of the rotor.[0005]The labyrinth seal uses the pressure drop void to cause a pressure drop in a downward leakage flow therein. The pressure drop inhibits le...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F01D25/00
CPCF01D25/00F01D11/001F05D2200/33F01D11/122F05D2220/31F01D11/02F01D25/04
Inventor ENDO, AKIRAYAMAGUCHI, KAZUYUKIMAGARA, YOHEIYOSHIDA, TOYOMIMURATA, KENICHIKUDO, TAKESHI
Owner MITSUBISHI HITACHIPOWER SYST LTD