JPS59226299A - Rotary fluid machine - Google Patents

Abstract

PURPOSE:To restrain an oscillating power generated in a labrinth seal and permit to respond the tendency of high pressure, high speed and high density of the rotary fluid machine by a method wherein a plurality of fins, regulating the flow direction of leaked fluid, are protruded on the surface of a casing, which is opposing to the disc or the cover of an impeller. CONSTITUTION:The fins 12, 13, positioned in surfaces vertical to the axial center of a rotary shaft 1 and extended into the radial directions respectively, are protruded shaft 1 and extended into the radial directions respectively, are protruded on the surface 22 of a casing opposing to the cove 33 of the impeller 3 as well as the surface 21 of the casing opposing to the disc 31 along the peripheral direction toward the cover 33 and the disc 31 with predetermined intervals. Gas, leaked from the outlet port 35 of th e impeller 3, flows into a clearance 10 between the surface 21 of the casing and the cover 33 as well as the clearance 8 between the surface 21 of the same and the disc 31 and tries to flow into the peripheral direction, however, it collides against the fins 12, 13 and the flow direction of the gas is changed into the radial direction orthogonal to the rotary shaft 1. Thereafter, the gas enters into the labyrinth seals 6, 7 without changing it's flow direction and reduces the oscillating power generated in the 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 X'lfi machine, a centrifugal Zorro 7, a centrifugal fan, or a centrifugal pump.

Figure 1 shows a partial longitudinal section of the final stage of a conventional multi-stage centrifugal compressor.
(2) is the casing, (4) is a spacer that rotates with the rotating shaft (1), and (5) converts the dynamic pressure of the gas discharged from the outlet of the impeller (3) into static pressure. Puifuyou! J, (6) (7) are casing (
2) shows the labyrinth seal fixed. rotate! i′
liI (11”a: ) A movement, then rotation axis (1)
At the same time, the impeller (3) and the spacer (4) rotate, and the gas from the previous stage flows in from the inlet (34) of the impeller (3) and passes through the disk (31), the cover (3:0), and the spacer (3:0) between them. While flowing through the flow path bounded by the cross-linked plates 3Z, it is biased by centrifugal force and is discharged from the outlet (E5) of the impeller (3), the majority of which enters the diffuser (5) where it is discharged. After the dynamic pressure is converted into static pressure, it is discharged from the compressor.

A part of the gas discharged from the outlet 09 of the inlet (3) flows through the gap (8) between the disk (casing surface 1 facing (+1)) as shown by the arrow (9), and flows into the labyrinth seal (6). ), and the energy is reduced here, but some of it (h) flows through this labyrinth seal (6) and flows into the gas suction port of the compressor. The other part of the discharged gas flows as shown by the arrow +tU through the gap (10) between the casing and the casing facing the cover, reaches the labyrinth seal (7), and is deenergized here. Some one stage flows through this labyrinth seal (7) and flows into the inlet (:+i>) of the impeller (3).

Figure 2 shows the labyrinth seal (6), j'p, l'll.
+ is shown, and the gas flowing in from the high pressure side on the left side of the figure expands and decreases as it enters the expansion chamber (62) through the gap between the tip of the strip (61) and the strip (4). The pressure in the expanded ff1 (62) is reduced, and the outflow of the gas is limited by turning it over, but the gas in this expanded ff1 (62) expands in the circumferential direction as the spacer (4) rotates. flows.

Figure 6 is a view along line 1 of Figure 2, where the center of rotation (0) of the spacer (4), that is, the rotating part, is eccentric by a distance (e) (0) due to some reason. '), the gap in the eccentric direction (fl is narrow < so, and the gap in the opposite direction (so)
becomes wider. Therefore, the flow velocity of the gas flowing in the circumferential direction in the expansion 1] good chamber (62) is greatest in the narrow gap (a), as shown by the length of the arrow in the figure, and gradually increases until the wide gap (ri). becomes the smallest.

Then, the pressure of the gas flowing through the right half gap (/, ,) 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. Due to the pressure difference, the rotating part receives a force shown by (F)8. This force (F) increases as the circumferential average flow velocity of the gas increases, and also increases as the average pressure of the gas in the gap increases.

On the other hand, as shown in Figure 4, the gas having a large circumferential average flow velocity at the entrance of the labyrinth seal (6) is decelerated as shown by curve (A), and the gas having a small circumferential average flow velocity is decelerated by curve (B). ), the speed increases and converges to a certain steady speed (c) which is smaller than the circumferential speed of the rotating part.

The gas coming out from the outlet C (5) of the impeller (3) is the outlet 0 (
The gas has a circumferential speed that is almost the same as the circumferential speed of the labyrinth seal (6) or (7). The circumferential speed of is greater than the circumferential speed of the rotating part of the labyrinth (6 bar 7), so the excitation force (F) of the rotor generated at the labyrinth seals (6) and (7) is significantly larger than that of the rotor. Also, if the gas pressure in the labyrinth seals (6) and (7) increases beyond a predetermined value, this excitation force (Fl) cannot be absorbed by the damping of the rotating shaft (11 bearings, etc.).

In order to address the above-mentioned problems, the present invention provides a plurality of fins on the casing surface facing the inner disk or/and cover for regulating the direction of flow of leakage fluid from the outlet of the impeller to the inlet of the labyrinth seal. This invention relates to a rotary fluid machine having an impeller characterized by protruding from the
The purpose is to dampen the excitation force generated in the labyrinth seal with a simple structure.

That is, in the present invention, an in-cover disk or (
and) A labyrinth is created by an extremely simple structure in which dog-shaped fins are protruded from the casing surface facing the cover to regulate the flow direction of the warm fluid from the outlet of the inner cavity to the inlet of the labyrinth seal. It is possible to reduce the circumferential flow velocity of the fluid or its pressure at the inlet of the labyrinth seal, thereby suppressing the excitation force generated in the labyrinth seal, and responding to the high pressure, high speed, and high density of this type of fluid machine. 1. Hereinafter, the present invention will be specifically explained with reference to the embodiments shown in FIG. 5 and below. FIG. 5 is a partial sectional view showing the final stage of a multi-stage centrifugal compressor to which the invention is applied, and FIG. 6 is a sectional view taken along the vt-vr line in FIG. In FIGS. 5 and 6, parts similar to those shown in FIG. 1 are given the same reference numerals.

The casing surface facing the cover C33+ of the impeller (3) and the casing surface facing the disc (31)
21), fins +t2'l and o3 extending in the radial direction in a plane substantially perpendicular to the axis of the rotating shaft (1) are arranged at predetermined intervals along the circumferential direction to cover (g), disk (
31).

The gas leaking from the outlet (3 [F] of the inlet S (3) is leaked from the gap between the outlet of the impeller (3) (the casing surface 21 at a circumferential speed approximately the same as the circumferential speed of the impeller (39) and the cover 433) (
10) and the gap j1 old 8) between the casing surface CJI) and the disk (31) and tries to flow in the circumferential direction,
Finn (12)! 1.3+, the flow is changed to radial direction perpendicular to the rotation axis (1) divided by 1, and enters the labyrinth seals (6) and (7).

Therefore, the flow velocity in the circumferential direction in the labyrinth seals (6) and (7) becomes as shown in FIG. 4 (B), and the excitation force (F) generated in the labyrinth seals f6 and (7) is reduced.

Therefore, the stability with respect to rotor vibration is increased, and the high pressure,
Greater vibration tolerance for higher speeds and higher density ratios.

The location where such fins are most effective is the leakage liquid flow path to the labyrinth packing (6) where the pressure is high and the pressure ratio is large, that is, the gap between the casing surface QD on the final stage disk (3I) side, Moreover, it is effective even if it is provided only at this location.

FIG. 7 is a sectional view corresponding to FIG. 6 showing a second embodiment of the present invention. The fins (13) are extended in the rotational direction of the rotating shaft (1) in a sno-irial shape, and the synergistic effect with the rotation of the impeller (3) allows leakage gas in the gap (8) to be directed to the diffuser (5). Trying to get it back.

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]

Fig. 1 is a partial longitudinal cross-sectional view showing the final stage of a conventional multi-stage centrifugal compressor, Fig. 2 is a cross-sectional view of the same labyrinth seal as above, Fig. 6 is a cross-sectional view taken along the line ■-■ in Fig. 2, FIG. 4 is a diagram showing changes in average flow velocity in the circumferential direction within the labyrinth seal. FIG. 5 is a partial vertical sectional view showing the final stage of an embodiment in which the present invention is applied to a multistage centrifugal compressor, and FIG.
It is a sectional view along the I-VI line. FIG. 7 is a diagram corresponding to FIG. 6 showing another embodiment of the present invention. In<-i...(3), Disk...C31),
Kaz-...(c), casing surface...t2+
) (2″IJ, Impeller outlet...(c), Labyrinth seal...(Gl(71, Fin...(12)
(131 Sub-agent Patent attorney Shige Okamoto 2 people outside the kiln Figure 2 L ■ Figure 5

Claims (1)

[Claims] The impeller is characterized in that a casing surface facing the impeller disk or (and) cover is provided with an algebraic fin protruding from the impeller's outlet to the labyrinth seal's inlet for regulating the direction of flow of leakage fluid. Rotating fluid machine with.