JPH1018994A - Liquid pump with inducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure a greater effect of suppressing cavitation in a liquid pump. SOLUTION: A return channel 40 is defined to be connected between annular space 38 and the inducer outlet including an intermediate portion 41 between an inducer blade 32 and an impeller 36. Which arrangement enables the extraction of part of liquid at the inducer outlet to forcibly inject the same part of liquid from a ring-like nozzle slit 39 defined at the annular space 38 toward the outer periphery of the inducer blade 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid pump with an inducer. More specifically, the present invention relates to a liquid pump with an inducer capable of obtaining a greater cavitation suppressing effect.

[0002]

2. Description of the Related Art For example, a space rocket is provided with a liquid pump for supplying a liquid fuel such as liquid hydrogen or liquid oxygen to a rocket engine. In addition, some high-speed ships are equipped with a liquid pump called a water jet propulsion device that obtains thrust by sucking seawater and injecting it backward.

[0003] In these liquid pumps, a rotary blade called an inducer is sometimes mounted in front of the impeller in order to improve suction performance.

FIG. 6 shows an example of an engine cycle of a space rocket, in which liquid hydrogen 3 discharged from a pump section 2 of a liquid pump 1 such as a liquid hydrogen pump and a liquid pump 4 such as a liquid oxygen pump. The liquid oxygen 6 discharged from the section 5 is sent to the combustion chamber 8 of the rocket engine 7 and is burned in the combustion chamber 8 to obtain a thrust. Then, a part of the liquid hydrogen 3 sent to the combustion chamber 8 of the rocket engine 7 is branched to cool the injection nozzle 9 of the rocket engine 7. Further, a part of the liquid hydrogen 3 discharged from the pump unit 2 of the liquid pump 1 such as a liquid hydrogen pump and a part of the liquid oxygen 6 discharged from the pump unit 5 of the liquid pump 4 such as a liquid oxygen pump are combined. The gas is sent to the gas generator 10, and these are burned by the gas generator 10 to generate driving gas for the turbine section 11 of the liquid pump 1 such as a liquid hydrogen pump and the turbine section 12 of the liquid pump 4 such as a liquid oxygen pump. I have to.

[0005] Of the above liquid pumps 1 and 4, for example, a liquid pump 4 such as a liquid oxygen pump is provided with an inducer 14 for improving the suction performance at a stage preceding the impeller 13 of the pump section 5, as shown in FIG. Is installed.

Reference numeral 15 is a liquid oxygen inlet of the liquid oxygen pump, 16 is a liquid oxygen outlet, 17 is a driving gas inlet of the liquid oxygen pump, and 18 is a driving gas outlet.

FIG. 8 shows an example of a liquid pump called a water jet propulsion device which is attached to a high-speed ship or the like. A suction pipe elbow 21 having a U shape having a seawater inlet 19 and a seawater injection port 20 is provided. A main shaft 25 connected to a driving device 24 such as an engine via a shaft sealing device 22 and a speed reduction device 23 at an axial position of the suction pipe elbow 21, and an impeller 26 attached to the main shaft 25. In addition, an inducer 27 for improving the suction performance is attached to the front stage of the impeller 26.

The liquid pumps 1, 4 such as the liquid hydrogen pump and the liquid oxygen pump used in the space rocket,
A liquid pump such as a water jet propulsion device used in a high-speed ship is driven under extremely strict conditions, so that cavitation (bubbles) is likely to be generated in the inducers 14 and 27, and the cavitation is generated. There is a possibility that performance degradation due to fluid vibration, shaft vibration, cracks due to stress fatigue on the blade surfaces of the inducers 14 and 27, and the like may occur.

Therefore, conventionally, the inducers 14, 27
In order to suppress the occurrence of cavitation in the part,
Measures have been taken to increase the clearance between the outer peripheral portions of the wings of the inducers 14 and 27 and the inducer liner, and to install an auxiliary tool such as a suction ring.

[0010]

However, the above liquid pump has the following problems.

That is, when a large clearance is provided between the outer peripheral portions of the wings of the inducers 14 and 27 and the inducer liner, or when an auxiliary tool such as a suction ring is installed,
Although a certain cavitation mitigation effect can be obtained, it is only a passive means and does not actively apply external energy, so its cavitation suppression effect is limited.

The present invention has been made in view of the above circumstances, and has as its object to provide a liquid pump with an inducer capable of obtaining a greater cavitation suppressing effect.

[0013]

According to the present invention, there is provided an impeller
In the liquid pump with the inducer provided with the inducer blades 32 and 52 in the preceding stage of the inducer blades 3 and 5,
The present invention relates to a liquid pump with an inducer, characterized in that nozzles 39 and 54 for ejecting a part of the inducer outlet liquid are provided on the inlet side portions of the inducer blades 32 and 52 toward the outer periphery of the inducer blades 32 and 52. Things.

In this case, the nozzles 39 and 54 are formed in the annular space 3 formed on the inlet side of the inducer blades 32 and 52.
The return channels 40, 55 provided in the annular spaces 8, 53 and for taking out a part of the inducer outlet liquid may be connected between the annular spaces 38, 53 and the inducer outlet.

In the above, the inducer outlet may be an intermediate portion 41, 56 between the inducer blades 32, 52 and the impeller 36.

The outlet of the inducer is connected to the impeller 36.
Outlet portions 42 and 58 may be used.

According to the above means, the following effects can be obtained.

As a result, the backflow on the outer peripheral side of the inducer blades 32, 52 is prevented and the flow is stabilized, and the static pressure on the outer peripheral side of the inducer blades 32, 52 is increased, so that the cavitation is reduced. As a result, the occurrence of fluid vibration due to cavitation is greatly suppressed.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show a first embodiment of the present invention, in which the present invention is applied to a liquid pump such as a liquid oxygen pump for a space rocket shown in FIGS.

In the drawing, reference numeral 28 denotes a liquid pump, 29 denotes a pump portion of the liquid pump 28, 30 denotes a pump casing constituting the pump portion 29, 31 denotes an inducer liner fitted and arranged inside the pump casing 30, and 32 denotes a pump liner. An inducer blade rotatably disposed inside the inducer liner 31; a liquid flow path 33 through which the liquid 35 sucked from the liquid inlet 34 passes; and an impeller 36 rotatably disposed downstream of the inducer blade 32; Reference numeral 37 denotes a scroll section for guiding the liquid 35 compressed by the impeller 36.

In the present invention, the pump casing 3
An annular space 38 that extends in the circumferential direction is formed at the entry side of the inducer blade 32 in the zero or the inducer liner 31. Specifically, the annular space 38 is formed, for example, between the pump casing 30 and the inducer liner 31 fitted to each other.

Further, the inducer blades 3 are removed from the annular space 38.
A ring-shaped nozzle slit 39 for ejecting a part of the inducer outlet liquid is provided toward the outer peripheral portion of No. 2.

Further, the annular space 38 and the pump casing 3
A return flow path 40 for taking out a part of the inducer outlet liquid is connected between the zero outlet and the inducer outlet portion. Specifically, the inducer outlet is an intermediate portion 41 between the inducer blade 32 and the impeller 36.

Next, the operation will be described.

The process of supplying liquid oxygen and liquid hydrogen to the rocket engine by using a liquid oxygen pump and a liquid hydrogen pump to obtain a thrust is the same as in FIGS.

In a liquid pump for a rocket engine such as the above liquid oxygen pump, when the impeller 36 is rotated,
A liquid 35 such as liquid oxygen is sucked from a liquid inlet 34,
It is discharged to the outside via the scroll part 37.

At this time, by rotating the inducer blade 32 disposed in the preceding stage of the impeller 36, the liquid 35 before entering the impeller 36 is pressurized and the suction performance is improved.

Since such a liquid pump for a rocket engine is driven under extremely strict conditions, it is easy for cavitation (bubbles) to be generated in the portion of the inducer blade 32, and the fluid accompanying the cavitation is generated. There is a possibility that problems such as deterioration in performance due to vibration, generation of shaft vibration, and generation of cracks in the inducer blade 32 due to stress fatigue may occur.

Therefore, in the present invention, the annular space 38 and the inducer outlet of the pump casing 30 (in this case,
Intermediate part 4 between inducer blade 32 and impeller 36
1), a part of the inducer outlet liquid is taken out, and a ring-shaped nozzle slit 39 formed in the annular space 38 is directed toward the outer peripheral portion of the inducer blade 32. A part of the outlet liquid is forcibly ejected.

Then, as shown by the broken line in FIG. 2, when there is no ejection of the inducer outlet liquid from the ring-shaped nozzle slit 39, a backflow occurs on the outer peripheral side of the inducer blade 32, and the liquid in this portion is generated. Although the axial flow speed of 35 was negative, as shown by the solid line in FIG. 2, by forcibly ejecting the inducer outlet liquid from the ring-shaped nozzle slit 39, the outer circumferential side of the inducer blade 32 was changed. The backflow is pushed back, and the axial flow velocity of the liquid 35 in this portion is changed to the plus side. Thereby, the flow of the liquid 35 from the inner peripheral side to the outer peripheral side of the inducer blade 32 is improved and stabilized, and stall and the like are prevented.

It is known that the occurrence of cavitation is greater on the outer peripheral side of the inducer blade 32, and that portion has a low pressure almost close to the saturated vapor pressure. Therefore, by forcibly ejecting a higher-pressure inducer outlet liquid to that portion, the static pressure on the outer peripheral side of the inducer blade 32 is increased, and the occurrence of cavitation is reduced.

As described above, as a result of stabilizing the flow and alleviating the cavitation, the generation of the fluid vibration due to the cavitation is largely suppressed.

FIG. 3 shows a second embodiment of the present invention. In the case of FIG. 1, the inducer outlet of the pump casing 30 is used as the outlet 42 of the impeller 36.
The higher-pressure inducer outlet liquid from the outlet portion 42 of the impeller 36 is forcibly sent to the annular space 38 through the return passage 40.

In this case, as in the above embodiment, the flow is stabilized and the cavitation is alleviated.
As a result, the occurrence of fluid vibration due to cavitation can be significantly suppressed.

Except for the above, the configuration is the same as that of the above embodiment, and the same operation and effect can be obtained.

FIG. 4 shows a third embodiment of the present invention, in which the present invention is applied to a liquid pump called a water jet propulsion device mounted on a high-speed ship or the like.

Since the overall structure of the water jet propulsion device is the same as that of FIG. 8, reference is made to FIG. 8 as necessary.

In the figure, reference numeral 43 denotes a plurality of casing pieces 44-4.
8 is a suction pipe elbow, 49 is a suction pipe elbow 43
, A main shaft 50 inserted through the suction pipe elbow 43, 51 an impeller mounted on the main shaft 50, 52 an inducer mounted on the front stage of the impeller 51 for improving suction performance. Wings.

In the present embodiment, an annular space 53 extending in the circumferential direction is formed in the suction pipe elbow 43 on the entry side of the inducer blade 52. Specifically, the annular space 53 is formed between the casing pieces 44 and 45 connected to each other.

Further, from the annular space 53, the inducer blades 5
A ring-shaped nozzle slit 54 for ejecting a part of the inducer outlet liquid is provided toward the outer peripheral portion of No. 2.

Further, a return channel 55 for taking out a part of the inducer outlet liquid is connected between the annular space 53 and the inducer outlet of the suction pipe elbow 43. Specifically, the inducer outlet is an intermediate portion 56 between the inducer blade 52 and the impeller 51.

In the liquid pump such as the water jet propulsion device, when the impeller 51 is rotated through the main shaft 50 by a driving device (not shown), the liquid 57 such as seawater is sucked and passed through the suction pipe elbow 43. And thrust is generated.

At this time, by rotating the inducer blade 52 disposed in the preceding stage of the impeller 51, the liquid 57 before entering the impeller 51 is pressurized and the suction performance is improved.

Since such a liquid pump such as a water jet propulsion device is driven under extremely strict conditions, the cavitation (bubbles) is likely to be generated at the inducer blade 52, and the cavitation is prevented. Performance degradation due to the accompanying fluid vibration, generation of shaft vibration,
There is a possibility that a problem such as generation of a crack due to stress fatigue may occur in the inducer blade 52.

Therefore, in the present invention, the annular space 53 and the inducer outlet of the pump casing 30 (in this case,
Intermediate portion 5 between inducer blade 52 and impeller 51
6), a part of the inducer outlet liquid is taken out, and the inducer exit liquid is taken out from the ring-shaped nozzle slit 54 formed in the annular space 53 toward the outer peripheral portion of the inducer blade 52. A part of the outlet liquid is forcibly ejected.

Then, as shown by the broken line in FIG. 2, when there is no ejection of the inducer outlet liquid from the ring-shaped nozzle slit 54, a backflow occurs on the outer peripheral side of the inducer blade 52, and the liquid in this portion Although the axial flow velocity of 57 was negative, as shown by the solid line in FIG. 2, the inducer outlet liquid was forcibly ejected from the ring-shaped nozzle slit 54, so that the outer peripheral side of the inducer blade 52 was The backflow is pushed back, and the axial flow velocity of the liquid 57 in this portion is changed to the plus side. Thereby, the flow of the liquid 57 from the inner peripheral side to the outer peripheral side of the inducer blade 52 is improved and stabilized, and stall and the like are prevented.

It is known that the occurrence of cavitation is larger on the outer peripheral side of the inducer blade 52, and that portion has a low pressure almost close to the saturated vapor pressure. Therefore, by forcibly ejecting a higher-pressure inducer outlet liquid to that portion, the static pressure on the outer peripheral side of the inducer blade 52 is increased, and the occurrence of cavitation is reduced.

As described above, as a result of stabilizing the flow and alleviating cavitation, generation of fluid vibration due to cavitation is greatly suppressed.

FIG. 5 shows a fourth embodiment of the present invention. In the case of FIG. 4, the inducer outlet of the suction pipe elbow 43 is used as the outlet 58 of the impeller 51 and the outlet 58 of the impeller 51 is used. In this case, the higher-pressure inducer outlet liquid is forcibly sent to the annular space 53 through the return flow path 55.

Also in this case, as in the above embodiment, the flow is stabilized and the cavitation is reduced.
As a result, the occurrence of fluid vibration due to cavitation can be significantly suppressed.

Except for the above, it has the same configuration as the above-described embodiments, and can obtain the same operation and effect.

It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the scope of the present invention.

[0054]

As described above, according to the liquid pump with the inducer of the present invention, an excellent effect that a larger cavitation suppressing effect can be obtained can be obtained.

[Brief description of the drawings]

FIG. 1 is a partially enlarged side sectional view of a first embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a position of an inducer blade and an axial flow velocity distribution.

FIG. 3 is a partially enlarged side sectional view of a second embodiment of the present invention.

FIG. 4 is a partially enlarged side sectional view of a third embodiment of the present invention.

FIG. 5 is a partially enlarged side sectional view of a fourth embodiment of the present invention.

FIG. 6 is a schematic system diagram showing an example of an engine cycle of a space rocket.

FIG. 7 is a partially cutaway side view of a conventional liquid oxygen pump.

FIG. 8 is a partially cutaway side view of a liquid pump called a water jet propulsion device according to a conventional example.

[Explanation of symbols]

 36,51 Impeller 32,52 Inducer blade 39,54 Nozzle (ring-shaped nozzle slit) 38,53 Annular space 40,55 Return flow path 41,56 Intermediate part (Inducer outlet) 42,58 Exit part (Inducer Exit)

Claims (4)

[Claims] In a liquid pump with an inducer provided with an inducer blade (32) (52) in a stage preceding the impeller (36) (51), the inducer blade (32) (52) is provided.
Characterized in that nozzles (39) and (54) for ejecting a part of the inducer outlet liquid are provided on the inlet side of the inducer toward the outer periphery of the inducer blades (32) and (52). pump. 2. An annular space (38) formed by a nozzle (39) (54) on the inlet side of the inducer blade (32) (52).
A return passage (40) (55) connected to the annular space (38) and (53) for removing a part of the inducer outlet liquid is provided between the annular space (38) and the inducer outlet. Liquid pump with inducer as described. 3. The liquid pump with an inducer according to claim 2, wherein the inducer outlet is an intermediate portion (41) (56) between the inducer blades (32) and (52) and the impeller (36). 4. An inducer outlet is connected to an impeller (3).
The liquid pump with an inducer according to claim 2, wherein the outlet part (42) (58) of (6) is provided.