JP2009002168A - Pump, and drive method of pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pump in which a yield has been enhanced by inhibiting satisfactorily the occurrence of asymmetrical cavitation in a pump, and to provide a drive method of the pump. <P>SOLUTION: A pump 1 has an inducer body 31 having a rotatably driven shaft portion 33 disposed at the upstream side of an impeller 14 of a pump for pressurizing liquid and a blade 34 formed spirally on the outer circumference thereof, for boosting liquid from the upstream side and causing it to flow toward the downstream side, and an inducer device 30 provided with an inducer housing 32 that surrounds the inducer body 31. An opening 41 is formed at a position corresponding to a halfway portion of the blade 34 of the inducer body 31 in the inducer housing 32, and fluid under pressure higher than that on the upstream side of the inducer body 31 is injected into the opening 41. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pump and a pump driving method.

Conventionally, turbo pumps that are driven to rotate at high speed have been used as devices for supplying high-pressure liquid hydrogen or liquid oxygen, such as for rocket engines. The turbo pump is required to operate under an extremely low inlet side pressure at which cavitation always occurs. Such a turbo pump is provided with an inducer in order to discharge a high-pressure fluid while satisfying the suction performance (see, for example, Non-Patent Document 1).
Kobayashi, “Effect of shaft vibration on the occurrence of asymmetric cavitation in inducers”, Journal of the Japan Society of Mechanical Engineers, Volume B, Vol. 71, No. 709 (2005-9), P2303-P2308, No. 04-1234

As shown in the above non-patent document, an inducer can suck fluid even if cavitation occurs to some extent, but if the pressure on the inducer inlet side is too low, asymmetric cavitation as an unstable phenomenon Has been confirmed to happen.
Asymmetric cavitation is a phenomenon in which the cavity of each blade of an inducer that grows with a uniform size as the pressure is reduced is fixed in a non-uniform size for some reason. When asymmetric cavitation occurs, a non-uniform fluid force is applied to the blades to generate vibrations synchronized with rotation, resulting in a defective product due to reduced reliability during operation of the pump. As an example of the cause of this asymmetric cavitation, there is a whirling (axial vibration) in the rotation shaft of the inducer. Therefore, conventionally, the occurrence of asymmetric cavitation has been prevented by suppressing the rotation of the rotating shaft in advance, but in order to suppress the amount of rotation of the rotating shaft, the balance of the shaft must be strictly adjusted. However, it is very difficult to precisely adjust the balance of the shaft, and when the balance adjustment is insufficient, the above-mentioned asymmetric cavitation (shaft vibration) occurs and the reliability as a pump cannot be obtained. As a result, there is a problem that the yield of the pump is lowered.

  The present invention has been made in view of such circumstances, and provides a pump and a pump driving method in which yield is improved by satisfactorily suppressing the occurrence of asymmetric cavitation in the pump. It is an object.

The present invention employs the following configuration in order to solve the above problems.
The pump of the present invention is disposed on the upstream side of the impeller of the pump that pressurizes the liquid, has a shaft portion that is rotationally driven, and blades that are spirally formed on the outer peripheral portion thereof, and the liquid from the upstream side. A pump having an inducer device that includes an inducer body that pressurizes and flows downstream, and an inducer casing that surrounds the inducer body, and corresponds to a middle part of the blades of the inducer body in the inducer casing An opening is formed at a position, and a fluid having a higher pressure than the upstream side of the inducer body is injected into the opening.

  The opening is preferably formed from the outside to the inside of the inducer casing so as to go from the upstream side where the liquid flows toward the downstream side.

  The inducer casing is preferably formed in a substantially circular ring shape in a sectional view, and a plurality of the openings are preferably formed along the circumferential direction of the inducer casing.

  Moreover, it is desirable that the opening is formed in the inducer casing along a flow direction generated by the rotation of the blade.

  Further, it is desirable that a part of the liquid pressurized by flowing to the downstream side of the inducer body is injected into the opening.

  The pump driving method of the present invention is provided on the upstream side of the impeller of the pump that pressurizes the liquid, and has a shaft portion that is rotationally driven and blades that are spirally formed on the outer peripheral portion thereof. A method of driving a pump having an inducer device comprising an inducer body for boosting the liquid and flowing it downstream, and an inducer casing surrounding the inducer body, wherein the inducer in the inducer casing is activated when the pump is activated A fluid having a pressure higher than that of the upstream side of the inducer main body is injected into an opening formed at a position corresponding to the middle part of the blade of the main body.

  Moreover, it is desirable to inject the fluid downstream of the inducer body into the opening.

According to the present invention, the following effects can be obtained.
By injecting a high-pressure fluid into the opening, asymmetric cavitation can be prevented from occurring in the blades of the inducer body, and a stable output can be obtained. Further, when asymmetric cavitation is prevented, complicated work such as adjustment of the shaft system is not necessary. Therefore, there is no possibility that the pump yield is lowered due to the poor adjustment of the shaft system as in the prior art, and as a result, the yield is improved.

  Next, an embodiment of the pump of the present invention will be described with reference to the drawings. In this embodiment, a centrifugal high speed pump (hereinafter referred to as a high speed pump) provided with an inducer will be described as an example. The high-speed pump according to the present embodiment is suitably used as a device for supplying high-pressure liquid hydrogen or liquid oxygen, such as for rocket engines. In addition, in this specification, upstream and downstream are prescribed | regulated with respect to the direction of the flow of the fluid supplied in a pump.

  As shown in FIG. 1, the high-speed pump 1 includes a pump body 10 and an inducer device 30. In the pump main body 10, a rotary shaft 12 is rotatably supported by a bearing 13 in a hollow main body casing 11, a centrifugal impeller 14 is connected to one end side of the rotary shaft 12, and a turbine 15 is connected to the other end side. Has been. An extension shaft 16 that is rotatably supported on the same axis is connected to one end side of the rotation shaft 12. An inducer device 30 is connected to the suction side (upstream side) of the centrifugal impeller 14.

  The inducer device 30 includes an inducer body 31 and an inducer casing 32 that surrounds the inducer body 31. The inducer body 31 is attached to the tip of the extension shaft 16, and includes a shaft portion 33 connected to the extension shaft 16, and a plurality of spirally fixed outer peripheral surfaces of the shaft portion 33 (in this embodiment, 3) blades 34. Here, the blades 34 are designed so that no backflow occurs. In FIG. 1, the shape of the blade 34 is simplified. About the number of the blade | wings 34 of the inducer main body 31, it can change suitably according to the kind of pump etc., for example, 4 sheets.

  The inducer casing 32 has a substantially hollow cylindrical shape, and is connected to a flange portion 17 formed on the upstream side of the main body casing 11 at a flange portion 35 formed on the pump main body 10 side by a bolt (not shown). ing. A tank (not shown) in which liquid fuel (fluid) L made of, for example, liquid hydrogen, liquid oxygen or the like is accommodated on the upstream side of the inducer device 30 by a bolt (not shown) or the like via the flange portion 36. It is connected.

  Here, FIG. 2 is a schematic cross-sectional configuration diagram of the inducer casing 32 viewed from the direction of the rotation axis of the blade 34. As shown in FIG. 2, the inducer casing 32 has a plurality of small through holes (openings) 41 formed uniformly along the circumferential direction. In the present embodiment, the through holes (openings) 41 are formed uniformly along the circumferential direction, but the through holes (openings) 41 may be non-uniformly arranged. The through hole 41 penetrates between the outer side surface and the inner side surface of the inducer casing 32, and the formation position of the through hole 41 on the inner surface side of the inducer casing 32 is a through hole on the outer surface side of the inducer casing 32. It is formed in a state shifted from the formation position of 41 in the rotational direction of the blade 34 of the inducer body 31. Specifically, the through hole 41 is formed in the inducer casing 32 along the flow direction of the liquid fuel L generated by the rotation of the blades 34.

FIG. 3 is an enlarged sectional view showing an inducer casing 32 in which the through hole 41 is formed and an inducer main body 31 provided therein.
As shown in FIG. 3, the through hole 41 is formed from upstream to downstream in the flow of the liquid fuel L. Further, the through hole 41 is formed at a position (indicated by a one-dot chain line in the figure) corresponding to the middle part of the blade 34 of the inducer body 31 in the inducer casing 32. The formation position of the through hole 41 corresponds to a region A that forms a starting point of asymmetric cavitation, which will be described in detail later (see FIG. 6).

  The liquid fuel L having a pressure higher than that of the upstream side of the inducer body 31 is injected into the through hole 41 through the supply pipe 52. Specifically, in the present embodiment, the liquid fuel L is supplied from the pump body 10. Since the liquid fuel L pressurized by the inducer device 30 is supplied to the pump body 10, the pressure of the liquid fuel L flowing in the pump body 10 is higher than that upstream (before pressure increase) of the inducer body. And become expensive. Therefore, the high-pressure liquid fuel L can be injected into the through hole 41 with a simple configuration.

  In addition, this invention is not limited to the said structure. For example, in the present embodiment, the supply pipe 52 for supplying the high-pressure liquid fuel L from the pump body 10 into the through hole 41 is provided, but the liquid fuel L supplied to the suction port 37 of the high-speed pump 1 is provided. A configuration may be adopted in which the liquid fuel L maintained at a high pressure is accommodated in another tank and injected into the through hole 41 via the supply pipe.

  In the high-speed pump 1 configured as described above, when the turbine 15 is rotated by the action of high-temperature and high-pressure gas, the centrifugal impeller 14 coaxial with the turbine 15 is rotationally driven, whereby the inducer body 31 is rotationally driven. Then, by this rotation, the pressure of the liquid fuel L from the tank is increased, sent out in the axial direction, and guided to the suction port 37 of the high-speed pump 1. The high-speed pump 1 is configured to increase the pressure of the liquid fuel L from the tank by the inducer main body 31 and flow the liquid fuel L to the centrifugal impeller 14 side, pressurize the liquid fuel L to a higher pressure by the high-speed rotation of the centrifugal impeller 14 and discharge it.

  Generally, an inducer provided in a high-speed pump generates a flow accompanied by cavitation, and an unstable phenomenon called asymmetric cavitation in which the outlet pressure decreases when the inlet pressure becomes lower than a predetermined value may occur. It has been confirmed. Asymmetric cavitation is a phenomenon in which the cavity of each blade of the inducer body that grows with a uniform size as the pressure is reduced is fixed in a non-uniform size state for some reason.

  FIG. 4 is a front view of the blades of the inducer body when asymmetric cavitation occurs. Cavitation occurs in the three blades constituting the blade in the direction opposite to the rotation direction of each blade, and the cavitation generated in each blade is different as shown in FIG. Thus, when asymmetric cavitation occurs, the balance of the fluid force acting on each blade is lost, and the pump outlet pressure (pump output) decreases as shown in FIG. FIG. 5 is a graph showing the relationship between the pressure on the inlet side (upstream side) and the pressure on the outlet side (downstream side) in a high-speed pump in which asymmetric cavitation has occurred. In addition, when asymmetric cavitation occurs, the amount of whirling around the rotating shaft of the blade increases and large shaft vibration occurs. A pump in which shaft vibration is generated is regarded as a defective product because it cannot be said that the quality of the product is maintained.

  By the way, as means for preventing the occurrence of asymmetric cavitation, it is conceivable to suppress the rotation of the rotating shaft in advance. In this case, it is necessary to strictly adjust the balance of the shaft system in order to suppress the amount of rotation of the rotating shaft. However, it is very difficult to precisely adjust the balance of the shaft, and if the balance is not adjusted sufficiently, asymmetric cavitation (shaft vibration) will occur, resulting in a defective product. End up.

  Hereinafter, the driving method of the high-speed pump 1 according to the present embodiment will be described, so that the high-speed pump 1 can improve the yield by satisfactorily suppressing the occurrence of asymmetric cavitation in the pump.

  In the high-speed pump 1 according to this embodiment, when the pump is operated, the inducer main body 31 rotates, and the pressurized liquid fuel L is sent to the inducer main body 31. Then, cavitation occurs in the blades 34 as the inducer body 31 rotates.

  Thus, the cavitation generated in the blades 34 may develop into asymmetric cavitation. On the other hand, as shown in FIG. 3, the high-speed pump 1 is a liquid whose pressure is increased by being sent to the pump body 31 from the through hole 41 provided at a position corresponding to the middle part of the blade 34 of the inducer body 31. A part of the fuel L is injected. The formation position of the through hole 41 corresponds to the region A that forms the starting point of asymmetric cavitation. That is, when cavitation occurs in the region A, it means that asymmetric cavitation occurs.

  Here, as a comparison, the case where the liquid fuel L is not injected from the through hole 41 will be described as an example, and the special effects obtained by the high-speed pump 1 according to the present embodiment will be described.

  FIG. 6A shows the state of cavitation generated in the blade 34 of the inducer body 31 when the high-pressure liquid fuel L is not injected from the through-hole 41, and FIG. 6B shows the high-pressure liquid from the through-hole 41. It is a figure which shows the state of the cavitation produced in the blade | wing 34 of the inducer main body 31 at the time of inject | pouring the fuel L. FIG. 6 (a) and 6 (b), the blades 34 are shown in a state where they are unfolded in the rotational direction. In FIG. 6, the region A indicated by the one-dot chain line is the through hole 41 shown in FIG. Corresponding to the formation region (that is, the region forming the starting point of asymmetric cavitation).

  As shown in FIG. 6A, when the high-pressure liquid fuel L is not injected from the through hole 41, the pressure at the suction port 37 of the high-speed pump 1 is different for each blade 34 when the pressure is lower than a predetermined value. Large cavitation will occur (occurrence of asymmetric cavitation).

On the other hand, in the inducer device 30 according to the present embodiment, the high-pressure liquid fuel L is injected from the through hole 41 formed in the region A forming the starting point of the asymmetric cavitation as described above, so that FIG. As shown in FIG. 4, it is possible to prevent cavitation from occurring in the region A that is the starting point of asymmetric cavitation. Therefore, asymmetric cavitation can be prevented from occurring.
FIG. 7 is a graph showing the relationship between the pressure on the inlet side (upstream side) and the pressure on the outlet side (downstream side) in the high-speed pump 1 according to this embodiment, and corresponds to FIG.
As shown in FIG. 7, the high-speed pump 1 according to the present embodiment does not generate asymmetric cavitation even when the pressure on the inlet side of the pump becomes low, and the pump outlet pressure (pump output) is stable. Can be obtained.

  As described above, according to the high-speed pump 1 according to this embodiment, asymmetric cavitation can be prevented by injecting the high-pressure liquid fuel L through the through hole 41. Further, in the high-speed pump 1 according to the present embodiment, a complicated operation such as strictly adjusting the shaft system such as the rotating shaft 12 and the bearing 13 is not necessary. Therefore, such a misalignment causes asymmetric cavitation, resulting in a pump failure and a decrease in yield. Therefore, the yield of the pump can be improved.

  Further, since the through hole 41 is formed in the inducer casing 32 from upstream to downstream, the high-pressure liquid fuel L injected from the through hole 41 is supplied from a tank (not shown) via the flange 36. The main stream of L can be smoothly merged. In addition, the through holes 41 are formed uniformly in the circumferential direction of the inducer casing 32. With this configuration, the high-pressure liquid fuel L is supplied to the blades 34 of the rotating inducer body 31, and accordingly, cavitation in the region A can be well prevented.

  Further, as shown in FIG. 2, the through hole 41 is formed in the inducer casing 32 along the flow direction of the liquid fuel L generated by the rotation of the blades 34. Thereby, when the high pressure liquid fuel L is injected, it is possible to satisfactorily prevent the pressure change from occurring in the surface layer portion of the blade 34.

In addition, this invention is not restricted to embodiment mentioned above, You may use the following aspects.
In the present embodiment, a through hole having a small hole is formed in the inducer casing of the inducer device to prevent asymmetric cavitation. However, a through hole having a larger hole, that is, a slit may be formed instead of the through hole. Alternatively, a similar through hole or slit may be formed in the casing on the upstream side of the blades of the axial flow pump or the centrifugal pump not provided with the inducer device.

It is a sectional side view of the high-speed pump concerning the embodiment of the present invention. It is the schematic sectional drawing which looked at the inducer casing from the rotating shaft direction of the blade. It is an expanded sectional view of an inducer casing and an inducer main part. It is a front view of the blade | wing at the time of asymmetrical cavitation generation | occurrence | production. It is a figure which shows the pressure relationship of the inlet_port | entrance and exit in the conventional high speed pump. It is a figure which shows the state of the cavitation produced in the blade | wing of an inducer main body. It is a figure which shows the pressure relationship of the inlet_port | entrance and outlet of the high-speed pump concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... High speed pump, 14 ... Centrifugal impeller (impeller), 30 ... Inducer apparatus, 31 ... Inducer main body, 32 ... Inducer casing, 33 ... Shaft part, 34 ... Blade | wing, 41 ... Through-hole (opening part), L ... Liquid fuel (liquid)

Claims (7)

The shaft is disposed upstream of the impeller of the pump that pressurizes the liquid, and has a shaft portion that is rotationally driven and blades that are spirally formed on the outer peripheral portion thereof, and pressurizes the liquid from the upstream side to the downstream side. A pump having an inducer device including an inducer body that flows and an inducer casing that surrounds the inducer body,
An opening is formed in the inducer casing at a position corresponding to the middle part of the blade of the inducer body, and a fluid having a pressure higher than that of the upstream side of the inducer body is injected into the opening. And pump.   2. The pump according to claim 1, wherein the opening is formed from the outside to the inside of the inducer casing so as to go from the upstream side to the downstream side where the liquid flows. The inducer casing is formed of a substantially hollow annular shape in cross-sectional view,
The pump according to claim 1, wherein a plurality of the openings are formed along a circumferential direction of the inducer casing.   The said opening part is formed in the said inducer casing so that the flow direction produced by rotation of the said blade | wing may be formed, The pump as described in any one of Claims 1-3 characterized by the above-mentioned.   5. The pump according to claim 1, wherein a part of the liquid pressurized by flowing to the downstream side of the inducer body is injected into the opening. The shaft is disposed upstream of the impeller of the pump that pressurizes the liquid, and has a shaft portion that is rotationally driven and blades that are spirally formed on the outer peripheral portion thereof, and pressurizes the liquid from the upstream side to the downstream side. A drive method for a pump having an inducer device comprising an inducer body to flow and an inducer casing surrounding the inducer body,
A fluid having a pressure higher than that of the upstream side of the inducer body is injected into an opening formed at a position corresponding to a middle part of the blade of the inducer body in the inducer casing when the pump is activated. To drive the pump.   The pump driving method according to claim 6, wherein a part of the fluid pressurized by flowing to the downstream side of the inducer body is injected from the opening.

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