JPS59226300A - Rotary fluid machine - Google Patents

Abstract

PURPOSE:To restrain the oscillating power of labyrinth seal by a simple structure by a method wherein a plurality of fins are provided in a clearance between the outer surface of a cover or the like for an impeller and the surface of a casing, which is opposing to the outer surface, and a cavity is formed between the outside rims of respective fins and the surface of the casing. CONSTITUTION:A plurality of fins 12, extending radially in planes substantially vertical to the axial center of a rotary shaft 1, are provided in the clearance 10 between the outer surface of the cover 33 for the impeller 3 and the surface 22 of the casing, which is opposing to the outer surface of the cover 33, with predetermined intervals along the peripheral direction. A plurality of fins 13, extending radially in surfaces substantially vertical to the axial center of the rotary shaft 1, are also provided in the clearance 8 between the outer surface of the disc 31 and the surface 21 of the casing, which is opposing to the outer surface of the disc 31, with predetermined intervals along the peripheral direction. The cavities 14, 15 are formed between the outside rims of respective fins 12, 13 and the surfaces 22, 21 of the casing respectively. According to this method, the flow directions of leaked gas flowed into the clearances 8, 10 are regulated by respective fins 12, 13 to reduce the oscillating power generated in the labyrinth seals 6, 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotary fluid machine having an impeller, such as a centrifugal compressor, centrifugal blower, centrifugal fan, or centrifugal pump.

Figure 1 is a partial longitudinal sectional view showing the final stage of a conventional multi-stage centrifugal compressor. (4) is a spacer that rotates together with the rotating shaft (1), and (5) is an impeller (
3) a diffuser that converts the dynamic pressure of the gas discharged from the outlet into static pressure; (6) and (7) indicate a labyrinth seal fixed to the casing (2). When the rotating shaft (1) is driven, the injector (3) and the spring (4) rotate together with the rotating shaft (1), and the bushing from the previous stage is driven by the impeller (3).
) from the inlet 04) of the disk (3I), the cover O;9 and the play bridged between them)'' (
While flowing through the flow path limited by 32, it is urged by centrifugal force and is discharged from the outlet 00m of the impeller (3),
Most of it enters the diffuser (5) where its dynamic pressure is converted into static pressure before being discharged from the compressor.

A part of the gas discharged from the outlet t3 of the impeller (3) is on the casing surface facing the outer surface of the disk t3).
The flow flows as shown by the arrow (9) between the gap (8) and the labyrinth seal (6), where the energy is reduced, but a small amount of the flow passes through the labyrinth seal (6) and flows through the labyrinth seal (6). '' and is sucked into the gas suction port of the compressor.
The other part of the gas discharged from the outlet 0 of the cover O
Between the outer surface of the casing surface (221) and the opposing casing surface (221)
Flows like the arrow (111) and labyrinth seal (71
1C, the power is reduced here, but some of it flows through this labyrinth seal (7) and enters the inlet (3) of the impeller (3).
4).

Figure 2 shows the details of the labyrinth seal (6), and the gas flowing in from the high pressure side on the left side of the figure passes through the gap between the tip of the strip (61) and the spacer (4) and enters the expansion chamber (62).
When entering the gas, it expands, deenergizes and decompresses, and then repeats this process to restrict the outflow of gas.
The gas in this first expansion chamber (62) flows circumferentially in the direction of rotation of the spacer (4) as the spacer (4) rotates.

Figure 6 is a cross-sectional view taken along line G in Figure 2.
) In other words, for some reason, the center of rotation (0) of the rotating part may have a distance (
e) When the eccentricity becomes (0'), the gap in the eccentric direction (c) becomes narrower, and the gap in the opposite direction (, q) becomes wider < t,
Cru. Therefore, the flow velocity of the gas flowing in the circumferential direction inside the expansion chamber (62) is highest in the narrow gap (, q), as shown by the length of the arrow in the figure, gradually increases, and becomes the lowest in the wide gap (, q). . Then, the pressure of the gas flowing through the right half gap (A) where the circumferential flow velocity of gas gradually increases becomes greater than the pressure of the gas flowing through the left half gap 0) where the circumferential flow velocity gradually decreases, and this pressure difference The rotating part receives the force shown in (F). This force (F) increases as the circumferential average flow velocity of the gas increases, and also increases as the average pressure of the gas within the gap increases.

On the other hand, as shown in Figure 4, the gas having a large average flow velocity in the circumferential direction at the entrance of the labyrinth seal (6) is decelerated as shown in curve (A) in the process of flowing through the labyrinth seal, and has a small average flow velocity in the same direction. As shown in the curve (B), the gas is accelerated and converges to a certain steady velocity (cl) which is smaller than the circumferential speed of the rotating part. has a circumferential speed that is almost the same as the circumferential speed of exit 05), and the labyrinth seal (6) or (7) passes through the gaps (8) and (10) while maintaining this circumferential speed.
), the circumferential velocity of this gas is much faster than the circumferential velocity of the labyrinth seal f61 (710), so the excitation force (F) of the rotor generated at the labyrinth seal f61 (71) is unexpectedly large. If the gas pressure within the labyrinth seal (6) increases beyond a predetermined value, this excitation force (Fl) cannot be absorbed by the damping of the bearings of the rotating shaft (1).

In order to address the above-mentioned problems, Misfire V1 is designed to prevent leakage fluid from the impeller ball outlet to the labyrinth seal inlet in the gap between the outer surface of the impeller disk or (and) cover and the opposing casing surface. A rotary fluid machine having a rotary fluid machine having a rotary roller, characterized in that a plurality of fins are provided to regulate the flow direction of the fluid, and a donut-shaped cavity is formed between the outer edge of these fins and the casing surface. The gate j is an attempt to dampen the excitation force generated in the labyrinth seal by means of a structure.

That is, in the present invention, the impeller disk or (
and) providing planting fins within the gap between the outer surface of the cover and the opposing casing surface for regulating the flow direction of leakage fluid from the outlet of the impeller to the inlet of the labyrinth seal.

Since a nut-shaped 2J11i is formed between the outer li of these fins and the gauging surface, these fins reduce the flow velocity in the circumferential direction of the leakage θ'IL body or its pressure, and The density of the fluid is temporarily increased near these fins. Then, this fluid with a density of -17 degrees is led to the cavity, where the density is softened. In this way, the turbulence of the leaked fluid in the gap can be guided to the entrance of the labyrinth seal in a rectified state, reducing the excess ridges and at the same time damping the excitation force generated in the two labyrinth seals, thereby reducing the linear flow. Can one machine respond to high pressure, high speed, and high density?

Hereinafter, the present invention will be explained in detail by referring to the embodiments shown in Figs. 6 is a sectional view taken along the line Vl-Vl in FIG. 5. In FIGS. 5 and 6, parts similar to those shown in FIG. Impeller (
3) The casing surface (2z
A plurality of fins az extending in the radial direction in a plane substantially perpendicular to the axis of the rotating shaft (1) are provided at intervals along the circumferential direction in the gap 1iIJ (uO) between the disk C31 and the disk C31. ) and the opposing casing surface 1)
A plurality of fins (13) extending radially in a plane substantially perpendicular to the axis of the rotating shaft (1) are provided at predetermined intervals along the circumferential direction in the gap (8) between the rotating shaft (1) and the rotating shaft (1). .

And fin 02) outside nJ green and casing surface (sha)
A cavity 11.4) is formed between the fins (13) and
A cavity 0■ is formed between the outer edge of the casing surface and the casing surface (2υ. The cavity t14) and the labyrinth seal (7
) A plurality of holes a01 are provided at predetermined intervals in the circumferential direction between the inlet of the cavity a and the drying billinth seal (6
) A plurality of holes 07) are provided at predetermined intervals in the circumferential direction.

The gas leaking from the outlet C3ω of the impeller (3) has a circumferential velocity that is approximately the same as the wind speed at the outlet 05 of the impeller (3), and the gas leaks from the nJJ gap (10
) and the gap (8) between the casing surface and the disk C), and tries to flow in the circumferential direction, but the fin (12 (1)
3) The flow is changed to a radial direction perpendicular to the axis of rotation (1). Then, the density of the leaking gas increases in the vicinity of these fins α21 (t3+), and the leaking gas with this density density is guided into the cavity 04) 0ω, and the density is softened by the fin α21 (t3+). After rectifying the flow, the gas is guided to the entrance of the labyrinth seal (61 (71) through the gap (1G) θD.
Since the flow direction is regulated by ~, the flow velocity in the circumferential direction within the labyrinth seal (6) (force) becomes as shown in Figure 4 (B), and occurs at the labyrinth seals (6) and (7). The excitation force (Fl) is reduced.

Therefore, the stability with respect to rotor vibration is increased, and the high pressure,
Vibration tolerance increases for high speeds and high densities.

The flow direction is regulated by the fins (12+031) and at the same time the gas is guided to the cavity 04) (15) to rectify the turbulence, thereby reducing excess leakage.

The location where such fins are most effective is the leakage fluid flow path to the ambilin packing (6) where the pressure is high and the pressure ratio is large, that is, the gap between the final stage disc C1υ side and the casing surface D. , and it is also effective even if it is provided only in this location.

FIG. 7 is a 1υi plane view corresponding to FIG. 6 showing a second embodiment of the present invention. The fins Q31 extend in a spiral shape in the direction of rotation of the rotating shaft (1), and by a synergistic effect with the rotation of the impeller (3), leak gas in the gap (8) is directed toward the diffuser (5). trying to return to.

Therefore, the flow velocity of the gas in the circumferential direction at the entrance of the labyrinth seal (6) is reduced, and the amount of leakage can also be reduced.

[Brief explanation of the drawing]

Figure 1 is a partial vertical sectional view showing the final stage of the conventional multi-stage centrifugal H:, Figure 2 is a cross-sectional view of the same labyrinth seal as above, Figure 6 is the line shown in Figure 2. FIG. 4 is a diagram showing changes in average flow velocity in the circumferential direction within the labyrinth seal. Fig. 5 shows the final stage of an embodiment in which the present invention is applied to a multi-I centrifugal compressor.
The figure is a cross-sectional view taken along the Vl-VT line in Figure 5.
The figure is a 'Z) diagram corresponding to FIG. 6 showing another embodiment of the present invention. Impeller...(3), Disc...c(1),
Cover...Odor, Casing surface...(2i1(22),
Impeller outlet 10. (G), Labyrinth Seal...
・(G)(7), Fin...f12)03), Cavity...tl 4) IJ51 Demon 2 figure

Claims (1)

[Claims] The outlet of the impeller leads to the inlet of the labyrinth seal in the gap between the outer surface of the impeller or cover and the opposing casing surface. In addition to providing multiple fins to regulate the flow direction of the delivered fluid,
There is a dot between the outer edge of these fins and the casing surface.
A rotary fluid machine having an impeller characterized by forming a nut-shaped cavity.