JPH1018992A - Liquid pump with inducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent cloud cavitation in a liquid pump. SOLUTION: Blades 33 to 35 of an inducer 36 are respectively provided, on their suction side faces at positions apart from their upstream ends as the references by the length of 30 to 50% their total length downward or the positions where sheet cavities apt to decay, with cloud-cavitation prevention bars 39, 37 and 38 extending in the directions perpendicular to the flows of liquid, to thereby stem the counter-flows of liquid.

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 preventing cloud cavitation.

[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. 4 shows an example of an engine cycle of a space rocket. A liquid hydrogen 3 discharged from a pump section 2 of a liquid pump 1 such as a liquid hydrogen pump and a pump of a liquid pump 4 such as a liquid oxygen pump are shown. 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 connected to the exit side of the combustion chamber 8 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 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 suction performance at a stage preceding the impeller 13 of the pump section 5 as shown in FIG. 5. Is installed.

The inducer 14 has, for example, a shape as shown in FIG. 6, and comprises a hollow hub portion 15 and three spiral blades 16.

In FIG. 5, 17 is a liquid oxygen inlet of the liquid oxygen pump, 18 is a liquid oxygen outlet, 19 is a driving gas inlet of the liquid oxygen pump, and 20 is a driving gas outlet.

FIG. 7 shows an example of a liquid pump called a water jet propulsion device mounted on a high-speed ship or the like, in which a suction pipe elbow 23 having a U shape having a seawater inlet 21 and a seawater injection port 22 is provided. A main shaft 27 connected to a driving device 26 such as an engine via a shaft sealing device 24 and a speed reduction device 25 at the axial position of the suction pipe elbow 23, and an impeller 28 attached to the main shaft 27. In addition, an inducer 29 for improving the suction performance is attached to a front stage of the impeller 28.

The inducer 29 has, for example, a shape as shown in FIG. 8, and includes a hollow hub portion 30 and a plurality of spiral blades 31, 32 in two stages.

[0010]

However, the conventional liquid pump with an inducer has the following problems.

That is, the liquid pumps 1 and 2 such as the liquid hydrogen pump and the liquid oxygen pump used in the space rocket
4 and a liquid pump such as a water jet propulsion device used in a high-speed ship are driven under extremely strict conditions, so that cavitation (bubbles) is generated in the inducers 14 and 29.

Of these, cloud-like cloud cavitation generated on the downstream side of the blades 16, 31, and 32 causes pressure fluctuations in the liquid to be sucked, which lowers the performance of the liquid pump and breaks the inducers 14, 29. It causes food and noise.

[0013] The above-mentioned cloud cavitation is a phenomenon that occurs at high speed and is non-stationary, so that it is difficult to observe and experiment, and little is known about the mechanism of its occurrence.

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 preventing cloud cavitation.

[0015]

SUMMARY OF THE INVENTION The present invention provides an impeller
In the liquid pump with the inducer provided with the inducer 36 in the preceding stage of 3, 28, the suction side surface of each of the blades 33 to 35 of the inducer 36 is downstream by about 30 to 50% of the total length with respect to the upstream end. The present invention relates to a liquid pump with an inducer, wherein cloud cavitation preventing bars 37 to 39 extending in a direction perpendicular to the flow of liquid a are installed at advanced positions.

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

When the inducer 36 is rotated, the blade 3
The sheet cavity is generated up to a position advanced by about 50% of the total length to the downstream side with respect to the upstream end of 3-35.

Then, when the sheet cavity develops,
A backflow occurs on the lower surface of the sheet cavity from the downstream end of the blades 33 to 35 to the upstream end of the blades 33 to 35.

Due to the influence, the sheet cavity collapses from the rear end side, and the collapsed bubbles are rolled up by the upstream of the winding, and a cloud-like cloud cavity is generated. This is a phenomenon called cloud cavitation.

In contrast to the above-described cloud cavitation, in the present invention, each of the blades 33 to 3 of the inducer 36 is provided.
5 of the suction-side surface, and 3
Cloud cavitation preventing bars 37 to 37% extending in a direction perpendicular to the flow of liquid a at a position advanced to the downstream side by about 0 to 50%, that is, a position where the collapse of the sheet cavity is observed.
By installing 39, the backflow is blocked by the cloud cavitation preventing bars 37 to 39.

As a result, collapse of the sheet cavity due to backflow is prevented, and generation of a cloud cavity is prevented.

As a result, pressure fluctuation due to cloud cavitation is prevented from occurring in the liquid to be sucked, and the performance of the liquid pump is reduced, the erosion of the inducer 36, and the generation of noise are prevented.

Further, since it is only necessary to install the cloud cavitation preventing bars 37 to 39, manufacturing and processing are easy, and the shape change of the inducer 36 is small. No problem.

[0024]

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

FIGS. 1 to 3 show an embodiment of the present invention.

A liquid pump such as a liquid hydrogen pump and a liquid oxygen pump used in a space rocket and a liquid pump such as a water jet propulsion device used in a high-speed ship are the same as those shown in FIGS. Refer to these figures as necessary.

In the present invention, an example in which the present invention is applied to an inducer 36 having three spiral blades 33 to 35 twisted by approximately 360 degrees is shown.

The surface of each of the blades 33 to 35 of the inducer 36, that is, the surface on the suction side, which is advanced by about 30 to 50% of the total length with respect to the upstream end with respect to the upstream end, is perpendicular to the liquid flow a. Cloud cavitation preventing bar 37 extending in the direction (in the figure, the radial direction of the inducer 36).
~ 39 are installed.

Specifically, a cloud cavitation preventing bar 37 is provided for the blade 33, a cloud cavitation preventing bar 38 is provided for the blade 34, and the blade 3 is provided with a cloud cavitation preventing bar 38.
5 for cloud cavitation prevention bar 39
Are provided.

In FIG. 3, reference numeral 40 denotes a sheet cavity generated at the upstream end of the blades 33 to 35;
5 is a cloud-like cloud cavity generated in the downstream portion of the blade 5, 42 is a re-entrant jet generated from the downstream end side to the upstream end side of the blades 33 to 35, and 43 is a back flow 42.
Is a winding upstream part of which is partially wound up.

Next, the operation will be described.

The operation of a liquid pump such as a liquid hydrogen pump and a liquid oxygen pump used in a space rocket and a liquid pump such as a water jet propulsion device used in a high-speed ship are the same as those shown in FIGS. .

In the present invention, each blade 3 of the inducer 36
3 to 35 surfaces, that is, positions on the suction-side surface advanced to the downstream side by about 30 to 50% of the total length with respect to the upstream end,
That is, at a position where the collapse of the seat cavity 40 is seen,
The direction perpendicular to the liquid flow a (in the figure, the inducer 36
(In the radial direction of the cloud cavities), the backflow 42 is blocked by the cloud cavitation prevention bars 37 to 39.

Thus, collapse of the sheet cavity 40 due to the backflow 42 is prevented, and generation of the cloud cavity 41 is prevented.

As a result, pressure fluctuation due to cloud cavitation is prevented from occurring in the liquid to be sucked, and the performance of the liquid pump is reduced, the erosion of the inducer 36, and the generation of noise are prevented.

Further, since it is only necessary to install the bar-shaped cloud cavitation preventing bars 37 to 39, the production and processing are easy, and the shape change of the inducer 36 is small. Also does not matter.

It should be noted that the present invention is not limited only 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.

[0038]

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

[Brief description of the drawings]

FIG. 1 is a front view of an inducer according to an example of an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrows II-II in FIG.

FIG. 3 is a side view for explaining a cause of occurrence of cloud cavitation when each blade of an inducer is assumed to be a two-dimensional blade.

FIG. 4 is a schematic system diagram illustrating an example of an engine cycle of a space rocket.

FIG. 5 is a partially cutaway side view of a conventional liquid oxygen pump.

FIG. 6 is a perspective view showing an inducer of the liquid oxygen pump.

FIG. 7 is a partially cutaway side view of a liquid pump called a water jet propulsion device according to a conventional example.

FIG. 8 is a perspective view showing an inducer of the water jet propulsion device.

[Explanation of symbols]

 13,28 Impeller 33-35 Blade 36 Inducer 37-39 Cloud cavitation prevention bar

Claims (1)

[Claims] In a liquid pump with an inducer having an inducer (36) at a stage preceding the impeller (13) (28), each of the blades (33) to (33) of the inducer (36) is provided.
A cloud cavitation preventing bar (37) extending in a direction perpendicular to the liquid flow (a) at a position on the suction side surface of (35), which is advanced by about 30 to 50% of the total length with respect to the upstream end, on the upstream side. To (39), a liquid pump with an inducer.