JPS61229903A - Axial turbo-machine - Google Patents

Abstract

PURPOSE:To reduce the leakage loss by providing an annular projection shelf larger than the outer diameter of balance hole on the upstream face of disc while providing a radial fin on the facing partition board. CONSTITUTION:An annular projection shelf 10b larger than the outer diameter of the balance hole 5 is provided on the upstream face of rotor disc 4. While a radial seal fin 12 having key type cross-section and a micro gap against said shelf 2 is provided on a partition board 2 facing against said shelf 10b. Since the majority of leaked vapor from the partition board will flow to the balance hole 5, the leakage loss to be produced at the stage can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is utilized in the technical field of improving turbine performance by minimizing leakage loss of steam at the nozzle exit route of a turbine stage.

BACKGROUND ART FIG. 2 is a cross-sectional view of a blade portion of a conventional turbine stage, and FIG. 3 is a cross-sectional view taken along line mm in FIG. 2, where l is a nozzle and 2 is a partition. plate, 3 is a moving blade, 4 is a disk, 5 is a balance hole, 6 is a partition plate labyrinth, 7
8a is a rotating shaft, 8a is a disk inlet side space, 9 is a nozzle outlet root portion, 10 is a baffle plate, and 11 is a root seal portion.

A rotor blade 3 is provided on the outer periphery of the rotary shaft 7 via a disk 4, and a partition plate 2 is provided in front of the disk 4 via a disk inlet side space 8a. A nozzle 1 is provided.

Discs 4 (normally spaced at equal intervals in the circumferential direction at right angles to the 2 disks (: 4
~5 balance holes 5 are provided. An annular baffle plate 10 is attached to the front of the disk 4 and to the outer peripheral side of the balance hole 5.

The amount of leakage from the partition plate labyrinth 6 portion due to the pressure difference before and after the nozzle 1 normally amounts to 1 to 2% of the turbine stage flow rate.

The amount of leakage is determined by the balance hole 5 provided in the disk 4.
Although it is desirable that the leakage completely pass through the balance hole 5, in the conventional structure, the clearance of the root seal part 11 tends to expand due to thermal expansion of the rotor, etc., and a part of the total leakage amount is
It leaks into the nozzle exit route 9 without passing through.

This leaked steam causes a significant reduction in turbine performance.

Problems to be Solved by the Invention The present invention aims to significantly reduce the leakage amount and minimize the leakage loss in the nozzle outlet route section 9 of the turbine stage as described above.

Means for Solving the Problems The present invention takes the following measures in order to solve the above-mentioned problems. That is, the radial seal fin has a key-shaped cross-sectional shape in which a shelf of an annular projection larger than the outer diameter of the balance hole is provided on the upstream surface of the disk, and a minute gap is provided from the opposing partition plate to the shelf of the annular projection. will be established.

The flow of steam leaking from the labyrinth 6 section of the working partition plate is stopped by the disc shelf at the entrance of the balance hole, and most of it flows into the balance hole 5 due to the sealing function of the seal fin, and the leakage at the nozzle exit route is stopped. The inflow becomes minute.

Embodiment An embodiment of the present invention is shown in FIG. 1 and will be explained. In the figures, the same reference numerals as in the conventional example above indicate the same parts.

In the rotor disk 4, a shelf 10b having an annular projection is provided on the outer diameter side and the entrance side of the balance hole 5.

The radial seal fins 12 having a key-shaped cross section provided on the shelf 10b and the partition plate 2 create a small gap, the leakage area becomes small, and the amount of leakage to the nozzle exit route 9 becomes extremely small.

The radial clearance between the shelf 10b and the fins 12 is selected in consideration of centrifugal force of the rotor and elongation due to heat.

Steam leaking from the labyrinth 6 part of the partition plate is removed from the shelf 10b provided on the rotor disk 4 at the entrance part 8 of the balance hole 5.
By using the dynamic pressure, the capacity of the balance hole 5 is increased, and due to the sealing function of the radial seal fin 12, most of the flow is
The leakage flow from the nozzle outlet route section 9 becomes extremely small.

Effects of the Invention According to the present invention, as described above, by strengthening the sealing function and increasing the capacity of the balance hole, most of the steam leaking from the partition plate flows to the balance hole, thereby reducing the leakage loss that conventionally occurred in the paragraph. decreases significantly. the result,
Turbine efficiency increases.

[Brief explanation of the drawing]

; Fig. 1 is a cross-sectional view of a blade section of a turbine and a stage showing the configuration of the present invention, Fig. 2 is a cross-sectional view showing the configuration of a conventional blade section, and Fig. 3 is a cross-sectional view taken along line mm in Fig. 2. It is. 1. Nozzle, 2. Partition plate, 3. Moving blade, 4. Disk, 5. Balance hole, 6. Partition plate labyrinth, 7. Rotating shaft, 8. Balance hole entrance, 9・・・
Nozzle exit root section, lOb... Shelf, 11... Root seal section, 12... Radial seal fin. Figure 1 Figure 2 Figure 3 11r4 arrow j! figure

Claims (1)

[Claims] An axial flow turbomachine having a balance hole penetrated through a disk fixed to a rotating shaft, wherein a shelf of an annular protrusion larger than the outer circumferential diameter of the balance hole is provided on the upstream surface of the disk, and opposing partition plates. An axial flow turbomachine provided with a radial seal fin having a key-shaped cross section and providing a minute gap with respect to the shelf of the annular projection.