RU2380575C2 - Auger centrifugal pump - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed pump comprises housing 1, impeller 2, auger 3, floating rings 4, and front sealing collar 5 of impeller 2. Said collar 5 has main 6 and additional 7 groove seals that form intermediate space 8 there between. The latter extends all over the length of auger 3, and, on the side opposite aforesaid groove seals 6, 7, communicates, via radial bores 9, with inlet 10 of auger 3. Lateral side 11 of intermediate space 8 can have helical ribs 12.

EFFECT: higher reliability, simplified design.

2 cl, 1 dwg

Description

The invention relates to the construction of gap seals of screw centrifugal pumps of turbopump units of liquid rocket engines and can be used in pump engineering.

A feature of slotted seals of screw centrifugal pumps is the presence of leaks through the seal slots from the pump high-pressure cavity to the low-pressure cavity.

These leaks, especially when pumping cryogenic liquids, affect both the efficiency of the pump and its cavitation properties. There are various schemes for introducing leaks at the entrance to the main stream, for example, see the book of Ovsyannikov BV, Chebaevsky V.F. et al. High-speed vane pumps, Mechanical Engineering, Moscow, 1975, p.203, Fig. 343.

There is a known constructive solution for a slotted seal of a screw centrifugal pump according to RU 2246041 C1, 10.02.2005, taken as a prototype aimed at eliminating the influence of "hot" leaks through slotted seals of the front shoulder of a centrifugal wheel on the energy characteristics of a pump. A known centrifugal screw pump comprises a housing, an inlet pipe, a centrifugal wheel, a screw, a main gap seal on the front sealing collar of the centrifugal wheel, an additional gap seal behind the main gap seal, and an additional cavity is made hydraulically between these gap seals in the inlet pipe at the level of the main gap seal, hydraulically communicated by the pipeline with the entrance of the inlet pipe.

This design of the screw centrifugal pump according to the prototype is functional, but complicates the design of the pump by introducing additional vibration-hazardous leakage pipelines, and if the engine runs on cryogenic components, for example, liquid hydrogen and liquid oxygen, then the additional pipelines must have reliable heat-proof insulation from the effects of heated engine surfaces. The invention is aimed at improving the reliability and simplifying the design of the turbopump unit.

This technical effect is achieved by the fact that in a screw centrifugal pump containing a housing, a centrifugal wheel, a screw, floating rings, a front wheel sealing collar on which the main and additional gap seals are made to form an intermediate cavity between them, according to the invention, the intermediate cavity between the gap seals is made for the entire length of the screw and at the end opposite from the gap seals, it is connected by radial holes to the inlet area of the screw.

This design completely eliminates the effect of the heated fluid passing through the slotted seal on the suction capacity of the centrifugal wheel and, at the same time, simplifies the design of the screw centrifugal pump and increases its reliability due to the exclusion of the additional structural element, the bypass pipe, for draining fluid leaks into the pump inlet. To intensify the cooling of the heated fluid passing through the main gap seal, screw ribs can be made on the side surface of the intermediate cavity.

The drawing shows a screw centrifugal pump according to the invention.

The pump contains a housing 1, a centrifugal wheel 2, a screw 3, floating rings 4, a front sealing collar 5 of the wheel, on which the main 6 and additional 7 gap seals are made with the formation of an intermediate cavity 8 between them.

According to the invention, the intermediate cavity 8 between the gap seals 6 and 7 is made over the entire length of the screw 3 and at the opposite end from the gap seals is connected by radial holes 9 with the inlet zone 10 of the screw 3.

On the side surface 11 of the intermediate cavity 8, helical ribs 12 are made to intensify the cooling of the heated leak fluid.

When the pump is in the screw 3 due to centrifugal forces from the flow swirl due to the difference in specific gravity, the liquid is divided into cold and heated zones. The dependence of the specific gravity on temperature is especially noticeable in cryogenic liquids, such as hydrogen, methane, oxygen, in which the dependence gradient is rather steep. The fluid flow around the periphery is colder, in the center - warm.

Leaks after the main gap seal enter the intermediate cavity 8, pass through the screw channels 12, intensively giving off heat to the structure, then the stream is crushed in the radial holes 9, entering the cold part of the stream in the inlet zone 10 of the screw, and moves to the shaft of the screw 3, giving up the remaining heat to the main stream at a considerable distance from the centrifugal wheel 2, which eliminates the influence of heated fluid leaks passing through the slotted seal 6 on the suction capacity of the centrifugal wheel 2.

Claims (2)

1. A screw centrifugal pump comprising a housing, a centrifugal wheel, an auger, floating rings, a front wheel sealing collar, on which the main and additional gap seals are made to form an intermediate cavity between them, characterized in that the intermediate cavity between the gap seals is made over the entire length of the screw and at the opposite end from the gap seals, it is connected by radial holes to the inlet area of the screw. 2. The screw centrifugal pump according to claim 1, characterized in that screw ribs are made on the side surface of the intermediate cavity.