Power plants – Combustion products used as motive fluid – Combustion products generator
Reexamination Certificate
2000-03-10
2001-08-07
Thorpe, Timothy S. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combustion products generator
C060S259000
Reexamination Certificate
active
06269647
ABSTRACT:
TECHNICAL ART
The present invention generally relates to fluid propellant rocket engines and more particularly to fluid propellant rocket engines that integrate as a single unit the turbomachinery for pumping the fluid propellant together with the main combustion chamber of the rocket.
BACKGROUND OF THE INVENTION
Liquid fuel rocket engines, for example as taught in U.S. Pat. Nos. 4,879,874, 4,901,525, and 5,267,437 generally employ turbomachinery that is distinct from the main rocket nozzle for pressurizing and/or gasifying the liquid propellants prior to injection into the main rocket nozzle. Furthermore, one or more of the propellant components may be adapted to cool the main rocket nozzle through a associated plumbing circuitry. Accordingly, such systems are generally costly and complex, and the added complexity tends to reduce reliability.
U.S. Pat. Nos. 3,541,793 and 3,577,735 teaches a turborocket engine wherein liquid propellants are pressurized by respective pumps that pressurize a liquid fuel and liquid oxidizer. One of the propellant components discharges first through the walls of the main combustion chamber for cooling purposes, and then into a precombustion chamber. A portion of the other propellant component is discharged in the precombustion chamber, and the remainder is discharged into the main combustion chamber. The effluent from the precombustion chamber drives a turbine that in turn drives the respective pumps. The effluent then discharges into the main combustion chamber. The discharge nozzles are stationary relative to the respective combustion chambers, which can result in temperature variations within the precombustion chamber than can be stressful to the turbine. Further, the use of liquid propellant for cooling the main combustion chamber increases cost, complexity and weight.
U.S. Pat. Nos. 4,769,996 and 4,870,825 teach rotary liquid fuel injection systems that incorporate rotary pressure traps, however these systems are incorporated into turbine engines that utilize a gaseous oxidizer. Neither of these patents teach a turborocket engine that provides for rotary injection of both fuel and oxidizer component.
U.S. Pat. No. 5,323,602 teaches an effusion cooling system for a gas turbine engine that uses air as the cooling medium. This patent does not teach a turborocket engine, nor does it teach the use of combustion gases from a precombustor for effusion cooling a main combustor.
SUMMARY OF THE INVENTION
The present invention overcomes the above-noted problems by providing a turborocket engine that integrates the functions usually associated with rocket propulsion main combustion chambers and the turbomachinery usually associated with the turbopumps used by liquid rocket engines into one unit, thereby eliminating most of the plumbing and cooling circuitry normally associated with liquid rocket engines. This results in a much lower cost and lower weight propulsion system than is provided by prior-art liquid rocket engines.
Liquid fuel and liquid oxidizer are provided from pressurized tanks at relatively low pressure to separate sections within a rotor system driven by a relatively low pressure ratio turbine that is powered the combustion effluent generated by a precombustor operated at a relatively rich fuel/oxidizer ratio such that the temperature of the partially combusted effluent can be tolerated by the turbine. The flow rates of liquid fuel and liquid oxidizer are controlled at the relatively low supply pressure with separate throttle control valves, which provides for improved control that is less costly and more reliable. Rotary pressure traps incorporated in the rotor system isolate the relatively low pressure outlets of the respective throttle control valves from the relatively high pressures of the precombustor and main combustor.
The rotor system imparts, by a centrifugal pumping means, rotational kinetic energy and centrifugal force to the liquid fuel and liquid oxidizer. The centrifugal pumping means comprises one or more longitudinal ribs or vanes on the inside surface of the outer wall of a hollow shaft portion with one or more discharge orifices in communication with one or more associated grooves formed between adjacent ribs or vanes. Generally the pressure drop across the discharge orifices is relatively small, and the discharge orifices are not necessarily filled with fluid during normal operation. Moreover, whereas there is generally a one-to-one relationship between grooves and discharge orifices, subject to the constraint of mechanical balance, either more than one discharge orifice, or no discharge orifices, may be in communication with a particular groove. Furthermore, whereas the discharge orifices are generally of uniform size and orientation, subject to the constraint of mechanical balance, different discharge orifices may be sized and oriented differently. The liquid is rotated by the ribs or vanes, and centrifugally accelerated through the discharge orifices, which imparts substantial radial and circumferential velocities to the injected liquids, thereby providing for complete mixing and distribution. The centrifugal pumping means of the present invention does not, however, incorporate a diffuser to convert kinetic energy back to pressure energy, as incorporated in many conventional centrifugal pumps. All of the liquid fuel and some of the liquid oxidizer is injected by rotary injection into the precombustor, and then mixed, vaporized, and partially combusted therein. The temperature of the effluent from the precombustor is controlled by the associated fuel/oxidizer mixture ratio. The rotary injection process provides for a more uniform temperature distribution within the associated toroidal combustion zones within the precombustor, thereby enabling the turbine to operate at a temperature closer to the material-dependent peak operating temperature.
Both the liquid fuel and the liquid oxidizer are centrifugally pumped. Accordingly, the rotor system incorporates concentric hollow sections, wherein the liquid oxidizer is supplied through and pumped from the center of a hollow main shaft, and the liquid fuel is pumped from an annular chamber concentric therewith. The elements of the centrifugal pumps, including the ribs/vanes and discharge orifices, are arranged and sized so as to not disturb the mechanical balance of the rotor system. However, the ribs/vanes and/or the discharge orifices may be non-uniformly spaced in accordance with this constraint.
A portion of the effluent from the precombustor is directed through the precombustor liner, over the outside of the main combustor liner, and into the main combustor through effusion cooling holes so as to cool the main combustor by effusion cooling. A portion of the fuel, either liquid or gaseous, may also be directed over the precombustor liner for cooling the precombustor, and then combined with the effluent stream used to cool the main combustor liner. Furthermore, a portion of the effusion cooling gases may be discharged in the main combustor so as to provide boundary layer cooling of the converging/diverging nozzle.
The relative amount of liquid oxidizer that is delivered to the precombustor and to the main combustor is set by the design of the liquid oxidizer distribution system within the main rotor system. The liquid oxidizer pump discharge is split at the pump exit, feeding the smaller portion of the flow to a rotating injection device which delivers the oxidizer to the precombustor. The rotating injection device also incorporates a rotary pressure trap to isolate the precombustor pressure from the main combustor pressure, thereby preventing the flow of precombustor gas therebetween through the rotary injection device. A portion of the liquid fuel is also fed into a similar rotating injection device proximate to the same axial plane, resulting in mixing and atomizing of the two liquids as they are slung from the shaft system. Combustion of the mixture occurs simultaneously with this mixing and atomization. Additional liquid fuel is injected into the precombustor to assis
Thompson Jr. Robert S.
Williams Gregg G.
Lyon P.C.
Thorpe Timothy S.
Torrente David J.
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