Turbopump, in particular for feeding rocket engines
A turbopump for feeding a low-thrust rocket engine comprises a pump, a turbine, and a common rotary shaft connected to the pump and to the turbine. First and second bearings closer respectively to the pump and to the turbine serve to support the common shaft. The second bearing is a hydrodynamic bearing connected to a gas supply source, and the turbopump also includes at least one dynamic sealing gasket around the shaft and interposed between the first and second bearings.
1. A turbopump, comprising:
a propellant pump;
a turbine;
a common rotary shaft connected to said propellant pump and to said turbine;
a first bearing and a second bearing, the first and second bearings supporting said common rotary shaft, said first bearing being closer than the second bearing to the propellant pump, and said second bearing being closer than the first bearing to the turbine; and
at least one dynamic sealing gasket around the common rotary shaft interposed between said first and second bearings,
wherein said second bearing is a hydrodynamic bearing connected to a gas supply source so that no seal is interposed between the second bearing and the turbine.
2. The turbopump according to claim 1 , wherein said propellant pump is a cryogenic fluid pump.
3. The turbopump according to claim 1 , wherein said dynamic sealing gasket is connected to a source of inert fluid.
4. The turbopump according to claim 1 , wherein said first bearing is connected to the propellant pump to lubricate the first bearing with fluid coming from the propellant pump.
5. The turbopump according to claim 4 , wherein said first bearing is a rolling bearing.
6. The turbopump according to claim 4 , further comprising:
an auxiliary pump to exhaust said fluid from the first bearing.
7. The turbopump according to claim 4 , wherein said common rotary shaft adopts a rest position in which a facial contact seal is closed around the common rotary shaft, and is movable in a movement axially from said rest position to a working position in which said facial contact seal is open, the movement being against a return force exerted by at least one resilient element.
8. The turbopump according to claim 7 , wherein said propellant pump presents an axial admission passage situated at an end of said propellant pump that is remote from said first bearing, and said working position is situated towards the propellant pump relative to said rest position.
9. The turbopump according to claim 8 , wherein, in said working position, an axial element secured to the common rotary shaft but free to rotate relative to the common rotary shaft comes into abutment, towards the propellant pump, against a stator secured to a casing of the turbopump.
10. The turbopump according to claim 8 , wherein, in said rest position, an axial element secured to the common rotary shaft comes into abutment, towards the turbine, against a stator secured to a casing of the turbopump.
11. The turbopump according to claim 1 , wherein said gas supply source for the hydrodynamic bearing is the turbine.
12. An assembly, comprising:
the turbopump according to claim 1 ; and
a propulsion chamber,
wherein said gas supply source for the hydrodynamic bearing is an outlet from a regenerative circuit of the propulsion chamber.
13. A rocket engine, comprising:
at least one propulsion chamber; and
the turbopump according to claim 1 to feed at least one propellant to said at least one propulsion chamber.
14. A rocket engine, comprising:
the assembly according to claim 12 .
15. A method of using the turbopump according to claim 7 , wherein the first bearing is lubricated by the fluid coming from the propellant pump, the method comprising:
preventing, with said facial contact seal, said lubricating fluid from passing towards the dynamic sealing gasket and the second bearing when the turbopump is stopped; and
opening said facial contact seal by axial movement of the common rotary shaft when the turbopump is started.