JP2013189916A - Pump, and mechanism for suppressing interference of pump leakage flow - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pump and a mechanism for suppressing the interference of a pump leakage flow that reduce the interference between fluid flowing back beyond a seal part of a flow path formed between the outer periphery of a front shroud of an impeller and a casing and a main flow sucked into the impeller via an inducer.SOLUTION: A pump includes a main shaft 1 rotating in a casing 2; an impeller 10 rotating in conjunction with the main shaft 1; an inducer 6 for supplying fluid to the impeller 10; a seal part of a first flow path 12 formed between the outer periphery of a front shroud 11 of the impeller 10 and the casing 2 and serving as a fluid refluxing flow path; and a cavity 13 formed by recessing a part of the casing 2 on the downstream side of the seal part and on the extension line of the first flow path 12.

Description

  The present invention relates to a pump that pressurizes fluid sucked through an inducer with centrifugal force.

  Patent Document 1 discloses a turbo pump including a shaft thrust balance mechanism capable of automatically aligning shaft thrust and capable of easily adjusting axial thrust balance.

JP 2007-085223 A

  In the pump of the turbo pump described in Patent Document 1, the fluid that flows back beyond the seal of the flow path formed between the outer periphery of the front shroud of the impeller and the casing becomes a leakage flow, and the impeller passes through the inducer. May interfere with the mainstream.

  The present invention solves the above-described problem, and a fluid that flows back beyond a seal portion of a flow path formed between the outer periphery of the front shroud of the impeller and the casing, and is sucked into the impeller through the inducer. An object of the present invention is to provide a pump that reduces interference with the main flow and a leakage flow interference suppression mechanism of the pump.

  In order to achieve the above object, the pump includes a main shaft that rotates in a casing, an impeller that rotates in conjunction with the main shaft, an inducer that supplies fluid to the impeller, an outer periphery of a front shroud of the impeller, and the A seal part of the fluid return flow path formed between the casing and a cavity downstream of the seal part and on the extended line of the return flow path with a part of the casing as a recess. , Including.

  With this configuration, the leakage flow of the fluid that has passed through the seal portion can be rectified. As a result, the interference between the leakage flow of the fluid that flows back beyond the seal portion of the flow path formed between the outer periphery of the front shroud of the impeller and the casing and the main flow sucked into the impeller via the inducer is reduced. Can do. And even if the leak flow of a seal part arises because a pump rotates at high speed, the influence of interference to a mainstream can be controlled. Further, since the pump can rotate at a high speed, it is possible to compress even a fluid having a small molecular weight.

  As a desirable mode of the present invention, it is preferable that the concave portion of the cavity has an annular shape in a cross section orthogonal to the rotation axis of the main shaft.

  With this configuration, the flow velocity of the fluid that has passed through the seal portion is relaxed, and the deviation of the velocity distribution at which the leakage flow joins the main flow can be suppressed. As a result, the pump can suppress the turbulent flow that occurs when the leakage flow merges with the main flow.

  As a desirable aspect of the present invention, it is preferable that the cavity has a plurality of swirl relaxation parts arranged in the annular recess for relaxing the swirling of the leakage flow of the fluid that has passed through the seal part.

  With this configuration, the swirl (swirl) of the leakage flow of the fluid that has passed through the seal portion is alleviated. As a result, the pump can suppress the turbulent flow that occurs when the leakage flow merges with the main flow.

  In order to achieve the above object, a leakage flow interference suppression mechanism of a pump includes an impeller that rotates in conjunction with a main shaft that rotates in a casing, an inducer that supplies fluid to the impeller, and a front shroud of the impeller. A seal portion of the fluid return flow path formed between the outer periphery and the casing; and a part of the casing on the downstream side of the seal portion and on the extension line of the return flow passage is a recess. And a cavity.

  With this configuration, the leakage flow of the fluid that has passed through the seal portion can be rectified. As a result, the interference between the leakage flow of the fluid that flows back beyond the seal portion of the flow path formed between the outer periphery of the front shroud of the impeller and the casing and the main flow sucked into the impeller via the inducer is reduced. Can do. And even if the leak flow of a seal part arises because a pump rotates at high speed, the influence of interference to a mainstream can be controlled. Further, since the pump can rotate at a high speed, it is possible to compress even a fluid having a small molecular weight.

  As a desirable mode of the present invention, it is preferable that the concave portion of the cavity has an annular shape in a cross section orthogonal to the rotation axis of the main shaft.

  With this configuration, the flow velocity of the fluid that has passed through the seal portion is relaxed, and the deviation of the velocity distribution at which the leakage flow merges with the main flow can be suppressed. As a result, the pump can suppress the turbulent flow that occurs when the leakage flow merges with the main flow.

  As a desirable aspect of the present invention, it is preferable that the cavity has a plurality of swirl relaxation parts arranged in the annular recess for relaxing the swirling of the leakage flow of the fluid that has passed through the seal part.

  With this configuration, the swirl (swirl) of the leakage flow of the fluid that has passed through the seal portion is alleviated. As a result, the pump can suppress the turbulent flow that occurs when the leakage flow merges with the main flow.

  According to the present invention, the interference between the fluid that flows back beyond the seal portion of the flow path formed between the outer periphery of the front shroud of the impeller and the casing and the main flow sucked into the impeller via the inducer is reduced. A pump and a leakage flow interference suppression mechanism of the pump can be provided.

FIG. 1 is a schematic piping system diagram of a rocket engine to which a pump according to an embodiment is applied. FIG. 2 is a schematic configuration diagram of a turbo pump including the pump according to the embodiment. FIG. 3 is a schematic partial cross-sectional view illustrating the pump according to the first embodiment. FIG. 4 is an explanatory diagram for explaining a leakage flow of the pump according to the first embodiment. FIG. 5 is an explanatory diagram for explaining the flow velocity distribution of the leakage flow of the pump according to the first embodiment. FIG. 6 is an explanatory diagram for explaining the flow velocity distribution of the leakage flow of the pump of the comparative example. FIG. 7 is an explanatory diagram for explaining a leakage flow of the pump according to the second embodiment. FIG. 8 is an explanatory diagram for explaining a state of the cavity shown in FIG.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(Embodiment 1)
FIG. 1 is a schematic piping system diagram of a rocket engine to which a pump according to an embodiment is applied. The rocket engine 100 uses part of the fuel as a coolant for the rocket combustor 101 and also as a drive medium for the turbo pump 50 and the turbo pump 60 that pressurize and pump the oxidant and fuel.

<Rocket engine>
The rocket engine 100 includes an injector 102 that can inject oxidant and fuel, and includes a rocket combustor 101 that can combust oxidant and fuel. Furthermore, the rocket engine 100 supplies a fuel supply line 90 for supplying fuel to the rocket combustor 101 as a piping system for supplying the oxidant and fuel to the rocket combustor 101 and circulating the oxidant and fuel to each part of the rocket engine 100; An oxidant supply line 91 for supplying an oxidant to the rocket combustor 101; a cooling medium / turbo pump drive medium supply line 92 for circulating fuel to each part of the rocket engine 100 as a cooling medium for cooling the rocket combustor 101; Is provided.

The fuel supply line 90 is composed of a plurality of pipes, and connects a fuel tank that stores liquid hydrogen as fuel (hereinafter referred to as “LH ₂ ”) and the injector 102 of the rocket combustor 101, to Configure the supply system. Similarly, the oxidant supply line 91 includes a plurality of pipes, and an oxidant tank that stores liquid oxygen (hereinafter referred to as “LOx”) as an oxidant, and the injector 102 of the rocket combustor 101. Are connected to form an oxidant supply system. The cooling medium / turbo pump drive medium supply line 92 includes a plurality of pipes, branches from the fuel supply line 90 at one end, and passes through a cooling passage 105 in the wall surface of the combustion chamber 103 in the rocket combustor 101 described later. The other end is connected to the inside of the nozzle 104 of the rocket combustor 101 to constitute a cooling medium / driving medium supply system.

  The rocket engine 100 can pump the oxidant to the rocket combustor 101 via the fuel turbo pump 50 and the oxidant supply line 91 that can pump the fuel to the rocket combustor 101 via the fuel supply line 90. It includes an oxidant turbo pump 60, a mixer 70 that mixes fuel vaporized by cooling the rocket combustor 101 and liquid fuel, and an igniter 80 that ignites the mixture of oxidant and fuel.

The fuel turbo pump 50 includes a pump 51 and a turbine 52. The turbine 52 is driven to rotate by hydrogen gas (hereinafter referred to as “GH ₂ ”) as fuel that has passed through the cooling passage 105 and is vaporized, thereby driving the pump 51. LH ₂ is pressurized and fed to the injector 102. The oxidant turbo pump 60 includes a pump 61 and a turbine 62. The turbine 62 is driven to rotate by GH ₂ as vaporized fuel that has passed through the cooling passage 105 to drive the pump 61, and the pump 61 pressurizes LOx of the oxidant supply line 91 and pumps it to the injector 102. To do.

Fuel supply line 90 includes, in order from the upstream side relative to the flow direction of the LH _2, it comprises a pump 51 of the turbo pump 50 for fuel, the main fuel valve 93, and a mixer 70. The oxidant supply line 91 includes a pump 61 of a turbo pump 60 for oxidant and a main oxidant valve 94 in order from the upstream side with respect to the flow direction of LOx.

The cooling medium / turbo pump drive medium supply line 92 branches from the fuel supply line 90 on the downstream side of the pump 51 and the upstream side of the main fuel valve 93 with respect to the flow direction of LH ₂ in the fuel supply line 90. The cooling medium / turbo pump drive medium supply line 92 is, in order from the upstream side with respect to the flow direction of LH _{2 in} the fuel supply line 90, the combustion chamber cooling valve 92c, the cooling passage 105, the thrust control valve 95, and the fuel The turbine 52 of the turbo pump 50 and the turbine 62 of the oxidant turbo pump 60 are provided.

  The turbine 52 of the turbo pump 50 for fuel and the turbine 62 of the turbo pump 60 for oxidant are arranged in series in the cooling medium / turbo pump drive medium supply line 92. The cooling medium / turbo pump driving medium supply line 92 also includes a cooling passage for cooling the nozzle 104 on the upstream side of the portion connected to the inside of the nozzle 104 at the other end. The specific configurations of the fuel turbo pump 50 and the oxidant turbo pump 60 will be described later.

  The cooling medium / turbo pump drive medium supply line 92 includes a merging pipe 96, a mixing ratio control pipe 97, and a bypass pipe 98. The merge pipe 96 branches from the main pipe of the cooling medium / turbo pump drive medium supply line 92 on the downstream side of the cooling passage 105 and the upstream side of the thrust control valve 95 and is connected to the mixer 70. The mixing ratio control pipe 97 is branched from the main pipe of the cooling medium / turbo pump drive medium supply line 92 on the upstream side of the turbine 62 of the turbo pump 60 for oxidant and on the downstream side of the turbine 52 of the turbo pump 50 for fuel. By connecting to the downstream side of the turbine 62, the turbine 62 is bypassed. The mixing ratio control pipe 97 includes a mixing ratio control valve 99. The bypass pipe 98 branches from the main pipe of the cooling medium / turbo pump drive medium supply line 92 on the downstream side of the branch portion of the merging pipe 96 and on the upstream side of the thrust control valve 95, and The turbine 52 and the turbine 62 are bypassed by connecting to the downstream side. The bypass pipe 98 includes a waist valve 98a.

The main fuel valve 93 adjusts the supply of LH ₂ to the injector 102 by opening and closing the fuel supply line 90. The main oxidant valve 94 adjusts the supply of LOx to the injector 102 by opening and closing the oxidant supply line 91. The combustion chamber cooling valve 92 c adjusts the circulation of LH ₂ and GH _{2 in} the cooling medium / turbo pump driving medium supply line 92 by opening and closing the cooling medium / turbo pump driving medium supply line 92. The thrust control valve 95 controls the number of revolutions of the turbine 52 by opening and closing the cooling medium / turbo pump drive medium supply line 92 to control the amount of GH ₂ introduced as the drive medium introduced into the turbine 52. With the above configuration, the thrust of the rocket engine 100 as a whole is controlled by controlling the pressurization of LH ₂ by the pump 51.

The mixing ratio control valve 99 controls the rotational speed of the turbine 62 by opening and closing the mixing ratio control pipe 97 to control the introduction amount of GH ₂ as a driving medium introduced into the turbine 62. With this configuration, by controlling the pressurization of LOx by the pump 61, the mixing ratio (LOx / GH ₂ ) in the entire rocket combustor 101, that is, the ratio of LOx and GH ₂ injected from the injector 102. Is controlled. When the GH ₂ vaporized by passing through the cooling passage 105 bypasses the turbine 52 and the turbine 62, the waist valve 98a opens and closes according to the bypass amount.

The mixer 70 mixes the cryogenic LH ₂ that has passed through the main fuel valve 93 and the hot GH ₂ that has vaporized after passing through the cooling passage 105, so that it can be supplied to the rocket combustor 101 as GH ₂ . Note that hydrogen as a fuel may have gas-liquid two phases of GH ₂ and LH _{2 on} the downstream side of the cooling passage 105 in the cooling medium / turbo pump drive medium supply line 92.

The rocket engine 100 configured as described above pumps LH ₂ supplied through the fuel supply line 90 to the rocket combustor 101 by the fuel turbo pump 50 and also through the oxidant supply line 91. The supplied LOx is pumped to the rocket combustor 101 by the oxidant turbo pump 60.

Rocket engine 100, a LOx and GH ₂ were mixed in the combustion chamber 103 of the rocket combustor 101, obtain the thrust by burning by ignition by the igniter 80 to the mixture. During this time, the cooling medium / turbo pump drive medium supply line 92 introduces part of the LH ₂ pumped by the fuel turbo pump 50 into the cooling passage 105 provided on the wall surface of the combustion chamber 103 in the rocket combustor 101. . Then, the low temperature LH ₂ cools the combustion chamber 103. LH _{2 that} has gained energy by cooling the combustion chamber 103 rises in temperature and gasifies to become GH ₂ . A part of the gasified GH ₂ is introduced into the mixer 70 through the junction pipe 96 and is mixed with LH _{2 in the} mixer 70.

The remaining GH ₂ is sequentially introduced into the turbine 52 of the turbo pump 50 for fuel and the turbine 62 of the turbo pump 60 for oxidant, and acts as a driving medium for the turbine 52 and the turbine 62. The turbine 62 is driven to rotate. Accordingly, as described above, the turbo pump 50 for fuel and the turbo pump 60 for oxidant pump LH ₂ and LOx. The GH ₂ that rotationally drives the turbine 52 and the turbine 62 is discarded into the nozzle 104 from the other end of the cooling medium / turbo pump driving medium supply line 92.

In this rocket engine 100, the fuel turbo pump 50, which has a high density and therefore requires a high output, is first driven by GH ₂ and then the oxidant turbo pump 60 is driven. The pressure of GH ₂ after driving the fuel turbo pump 50 and the oxidant turbo pump 60 is considerably lower than the pressure before the first turbine 52 inlet, and the pressure before the turbine 52 inlet. Therefore, it is discharged into the nozzle 104 as a low pressure portion of the rocket combustor 101.

<Turbo pump>
FIG. 2 is a schematic configuration diagram of a turbo pump including the pump according to the embodiment. The turbo pump 50 or the turbo pump 60 includes a main shaft 1 that is rotationally driven, an impeller 10 that is fixed to the main shaft 1, a turbine blade 8 that is fixed to the main shaft 1, an inducer 6 that introduces liquid, and a casing 2. The bearing 4 and the bearing 5 that support the rotation of the main shaft 1, and the mechanical seal 7 that prevents liquid such as LOx and LH ₂ from leaking from the gap between the main shaft 1 and the casing 2 are included. In the turbo pump 50 or the turbo pump 60, the main shaft 1 connects the impeller 10 and the turbine blade 8 in series.

The inducer 6 is an axial flow type impeller, and is accommodated in the casing 2 so as to be coaxially connected to the turbine blade 8 and the impeller 10 and the main shaft 1. The direction of arrow Pi indicates the supply direction of LH ₂ or LOx supplied from the fuel tank or oxidant tank. When the turbine blade 8 is rotated by high-temperature and high-pressure gas and the interlocking impeller 10 is rotationally driven, the impeller of the inducer 6 rotates in synchronization with this. For this reason, the inducer 6 guides LH ₂ or LOx to the suction port of the impeller 10 and suppresses cavitation generated in the impeller of the impeller 10 in order to maintain the suction performance of the impeller 10.

The impeller 10 is rotated in the casing 2 and acts as a centrifugal pump. That is, the pumps 51 and 61 are centrifugal pumps that pressurize the fluid sucked through the inducer 6 with centrifugal force. The impeller 10 pressurizes the liquid (fluid) such as LOx and LH ₂ sucked through the inducer 6 and gives energy to the liquid such as LOx and LH ₂ . Pressurized liquids such as LOx and LH ₂ are discharged in the direction of the arrow Po and supplied to the fuel supply line 90 or the oxidant supply line 91 shown in FIG.

As described above, the turbines 52 and 62 pass through the cooling passage 105 shown in FIG. 1 and vaporize, and are driven to rotate by GH ₂ supplied from the direction of the arrow Gi. That is, GH _{2 as} a driving medium pushes the turbine blade 8 to rotate the main shaft 1. Note that the driving medium GH ₂ is discharged in the direction of the arrow Go and is sent to the combustion chamber 103 as shown in FIG.

<Pump>
FIG. 3 is a schematic partial cross-sectional view illustrating the pump according to the first embodiment. As shown in FIG. 3, the casing 2 includes a stationary wall 3 located on the impeller 10 on the turbine blade 8 side. The impeller 10 includes a front shroud 11 and a rear shroud 15 so as to cover the outer peripheral surface of the impeller 10. A first flow path 12 through which liquid flows is formed in a gap between the outer peripheral surface of the front shroud 11 and the casing 2 facing the front shroud 11. The casing 2 is formed with a cavity 13 in which a part of the casing 2 on the extension line of the first flow path 12 that is a reflux flow path is a recess.

  A second flow path 16 through which liquid flows is formed in a gap between the rear shroud 15 of the impeller 10 and the stationary wall 3 facing the impeller 10. The second flow path 16 includes a multistage orifice including a first orifice 17 and a second orifice 18. The 1st orifice 17 and the 2nd orifice 18 adjust the pressure of the 2nd flow path 16, maintain an axial direction balance, and reduce a possibility that the impeller 10 may contact with another member.

  Further, the balance hole 19 is connected to the second flow path 16, and the liquid in the second flow path 16 is returned to the blade inlet of the impeller 10. The balance hole 19 is inclined so that the side communicating with the wing is located on the radially outer side than the side communicating with the second flow path 16. For this reason, the liquid returning from the balance hole 19 can suppress turbulent flow that disturbs the inflow direction of the main flow of the impeller 10. As a result, the pumps 51 and 61 can maintain the pump performance.

  The leakage flow Cr ejected between the inducer 6 and the impeller 10 through the cavity 13 described above merges with the main flow Cm of the fluid supplied by the inducer 6. FIG. 4 is an explanatory diagram for explaining a leakage flow of the pump according to the first embodiment. FIG. 4 is a partially enlarged view of FIG.

  As shown in FIG. 4, in the first flow path 12, a seal portion is formed by a protrusion 11a provided on the inner diameter side of the front shroud 11 of the impeller 10 and a return inner surface 2a of the casing 2 facing the protrusion 11a. Is formed. The cavity 13 is an annular shape in a cross section orthogonal to the rotation axis of the main shaft 1 shown in FIG. 3, with a part of the casing 2 on the extension line of the first flow path 12 being a recessed portion on the downstream side of the seal portion. .

  The leakage flow Cs immediately after the seal portion shown in FIG. 4 is accelerated between the protruding portion 11a and the return inner surface 2a, and the flow velocity tends to increase. Further, as the impeller 10 rotates, the protrusion 11a of the front shroud 11 also rotates. For this reason, the leakage flow Cs becomes a swirl flow swirling in the same direction as the rotation direction of the impeller 10. The cavity 13 receives the leakage flow Cs in the recess, and sets the leakage flow Ch to reverse the flow at the bottom of the cavity 13. The leakage flow Cs and the leakage flow Ch are opposed to each other, and the flow velocity of the leakage flow Ch decreases. The leakage flow Ch flows through the main flow connection channel 21 formed between the casing 2 and the end portion of the front shroud 11.

  FIG. 5 is an explanatory diagram for explaining the flow velocity distribution of the leakage flow of the pump according to the first embodiment. FIG. 6 is an explanatory diagram for explaining the flow velocity distribution of the leakage flow of the pump of the comparative example. As shown in FIG. 5, the flow velocity distribution of the leakage flow Cr according to the first embodiment is such that the difference between the flow velocity close to the casing 2 and the flow velocity close to the shroud 11 is small because of the cavity 13. As described above, the leakage flow Ch reverses the flow at the bottom of the cavity 13. For this reason, in the mainstream connection flow path 21, the leakage flow Cr can increase the flow velocity distribution flowing along the front shroud 11 of the impeller 10.

  When there is no cavity 13, the leakage flow Cs directly collides with the wall surface of the casing 2, and becomes a leakage flow Cr ejected between the inducer 6 and the impeller 10 along the wall surface of the casing 2. That is, when there is no cavity 13, the flow velocity distribution of the leakage flow Cr shown in FIG. 6 is such that the flow velocity near the casing 2 is larger than the flow velocity near the front shroud 11. As a result, the speed of the leakage flow Cs increases, and the influence of interference between the leakage flow Cs and the main flow Cm may be increased.

  5 and 6, the flow velocity distribution of the leakage flow Cr according to the first embodiment is leveled from the casing 2 to the front shroud 11 because of the cavity 13. As described above, the pumps 51 and 61 according to the first embodiment can rectify the leakage flow Cs in the main flow connection flow path 21 from the casing 2 to the front shroud 11 so that the flow velocity distribution is leveled. The pumps 51 and 61 according to the first embodiment can suppress the maximum flow velocity of the leakage flow Cs when interfering with the main flow Cm.

  As described above, the pumps 51 and 61 according to the first embodiment include the main shaft 1 that rotates within the casing 2, the impeller 10 that rotates in conjunction with the main shaft 1, the inducer 6 that supplies fluid to the impeller 10, The seal portion of the first flow path 12 of the fluid formed between the outer periphery of the front shroud 11 of the impeller 10 and the casing 2, is downstream of the seal section, and is on the extension line of the first flow path 12. A cavity 13 having a part of the casing 2 as a recess.

With this configuration, the leakage flow of the fluid that has passed through the seal portion can be rectified. As a result, the leakage flow Cr of the fluid that flows back beyond the seal portion of the flow path formed between the outer periphery of the front shroud 11 of the impeller 10 and the casing 2, and the main flow sucked into the impeller 10 via the inducer 6 Interference with Cm can be reduced. In other words, the pump leakage flow interference suppression mechanism that reduces interference between the leakage flow Cr and the main flow Cm includes an impeller 10 that rotates in conjunction with the main shaft 1, an inducer 6 that supplies fluid to the impeller 10, and an impeller 10. The seal portion of the first flow path 12 of the fluid formed between the outer periphery of the front shroud 11 and the casing 2, and the casing 2 downstream of the seal section and on the extension line of the first flow path 12. And a cavity 13 having a part thereof as a recess. And even if the leak flow Cr of a seal part arises by rotating at high speed, the pumps 51 and 61 can suppress the influence of the interference with the main flow Cm. The pump 51 and 61 may be compressed less fluid molecular weight, for example, even LH ₂ so enables high-speed rotation.

(Embodiment 2)
Next, pumps 51 and 61 according to the second embodiment will be described. FIG. 7 is an explanatory diagram for explaining a leakage flow of the pump according to the second embodiment. FIG. 8 is an explanatory diagram for explaining a state of the cavity shown in FIG. In the following description, the same components as those in the above-described embodiment are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIGS. 7 and 8, the cavity 13 has a plurality of swirl relaxation portions 13 </ b> A that relax the swirling of the leakage flow Cs of the fluid that has passed through the seal portion, arranged in an annular recess. In the present embodiment, the swirl relaxation portion 13A of the cavity 13 is a plurality of holes that further recesses a part of the bottom of the recess as shown in FIG. As shown in FIG. 8, the holes are preferably arranged at equal intervals in the circumferential direction of the annular recess in the cross section orthogonal to the rotation axis of the main shaft 1.

  The leakage flow Cs immediately after the seal portion shown in FIG. 7 is accelerated between the protruding portion 11a and the return inner surface 2a, and the flow velocity tends to increase. Further, as the impeller 10 rotates, the protrusion 11a of the front shroud 11 also rotates. For this reason, the leakage flow Cs becomes a swirl flow swirling in the same direction as the rotation direction of the impeller 10.

  The cavity 13 receives the leakage flow Cs in the recess, and sets the leakage flow Cha to reverse the flow at the bottom of the cavity 13 or the swirl relaxation portion 13A. The leakage flow Cs has a different distance to reach the main flow connection flow path 21 when it is reversed at the bottom of the cavity 13 and when it is reversed at the swirl relaxation portion 13A. For this reason, the leakage flow Cha changes in accordance with the arrangement in the circumferential direction of the annular recess of the swirl relaxing portion 13A in a cross section in which the distance for reversing the flow is orthogonal to the rotation axis of the main shaft 1. Thereby, the swirl (swirl) of the leakage flow Cs of the fluid that has passed through the seal portion is alleviated. As shown in FIG. 7, the leakage flow Cs and the leakage flow Cha are opposed to each other, and the flow velocity of the leakage flow Cha decreases. The leakage flow Cha flows along the front shroud 11 in the main flow connection channel 21 and becomes a leakage flow Cr ejected between the inducer 6 and the impeller 10.

  As described above, the cavity 13 arranges the plurality of swirl relaxing portions 13A for relaxing the swirling of the leakage flow Cs of the fluid that has passed through the seal portion in the annular recess. With this configuration, the swirl (swirl) of the leakage flow Cs of the fluid that has passed through the seal portion is reduced. As a result, the pumps 51 and 61 can suppress the turbulent flow that occurs when the leakage flow Cs merges with the main flow Cm.

  The swirl relaxation portion 13A is a plurality of holes that further recesses a part of the bottom of the recess, but other modes may be used as long as the swirl (swirl) of the fluid leakage flow Cs that has passed through the seal portion is relaxed. . For example, the swirl relaxing portion 13A may be a plurality of convex portions or raised portions that further raise a part of the bottom portion of the concave portion. In addition, it is preferable that the plurality of convex portions or raised portions are arranged at equal intervals in the circumferential direction of the annular concave portion in a cross section orthogonal to the rotation axis of the main shaft 1. Or swirl relaxation part 13A is good also as a several wall body which partitions a recessed part. The plurality of wall bodies are preferably arranged at equal intervals in the circumferential direction of the annular recess in the cross section orthogonal to the rotation axis of the main shaft 1.

DESCRIPTION OF SYMBOLS 1 Main shaft 2 Casing 3 Static wall 4, 5 Bearing 6 Inducer 7 Mechanical seal 8 Turbine blade 10 Impeller 11 Front shroud 12 1st flow path 13 Cavity 13A Swirl relaxation part 15 Rear shroud 16 2nd flow path 17 1st orifice 18 1st 2 orifice 19 balance hole 50, 60 turbo pump 51, 61 pump 52, 62 turbine 70 mixer 80 igniter 90 fuel supply line 91 oxidant supply line 92c combustion chamber cooling valve 92 cooling medium / turbo pump drive medium supply line 93 main fuel Valve 94 Main oxidizer valve 95 Thrust control valve 96 Junction pipe 97 Mixing ratio control pipe 98a Waist valve 98 Bypass pipe 99 Mixing ratio control valve 100 Rocket engine 101 Rocket combustor 102 Injector 103 Combustion chamber 104 Nozzle Cs, Ch, Cha, Cr Leakage flow Cm Main flow

Claims (6)

A spindle that rotates in the casing;
An impeller that rotates in conjunction with the main shaft;
An inducer for supplying fluid to the impeller;
A seal portion of the fluid return flow path formed between the outer circumference of the front shroud of the impeller and the casing;
A cavity in which a part of the casing on the downstream side of the seal part and on the extension line of the reflux channel is a recess;
A pump characterized by including.   The pump according to claim 1, wherein the concave portion of the cavity has an annular shape in a cross section orthogonal to the rotation axis of the main shaft.   3. The pump according to claim 2, wherein the cavity has a plurality of swirl relaxation portions arranged in the annular concave portion for relaxing swirling of a leakage flow of the fluid that has passed through the seal portion. An impeller that rotates in conjunction with a main shaft that rotates in the casing;
An inducer for supplying fluid to the impeller;
A seal portion of the fluid return flow path formed between the outer circumference of the front shroud of the impeller and the casing;
A cavity in which a part of the casing on the downstream side of the seal part and on the extension line of the reflux channel is a recess;
A leakage flow interference suppression mechanism for a pump characterized by comprising:   The leakage flow interference suppression mechanism for a pump according to claim 4, wherein the concave portion of the cavity has an annular shape in a cross section orthogonal to the rotation axis of the main shaft.   The pump leakage flow interference suppression mechanism according to claim 5, wherein the cavity has a plurality of swirl relaxing portions arranged in the annular recess for relaxing swirling of the leakage flow of the fluid that has passed through the seal portion.

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