The present invention relates to aerospace systems, and more particularly to an oil cooling arrangement for an aerospace system, as well as a method of cooling oil.
A large number of applications require cooling of various system fluids, such as oil, for example. One application relates to a space launch vehicle that requires a power source for an engine thrust vector control system. Currently, the power source utilizes a hot gas, such as hydrazine, to drive a turbine that provides mechanical rotating power to a hydraulic pump, generator or other power conversion device. Transmission of this power typically results in heat generation within the power device due to mechanical efficiency losses. In applications having operating durations exceeding several minutes or hours, heat generation must be managed to avoid system failure. Efforts to effectively manage the heat generation are complicated by the requirement that the power device must operate in a space vacuum operating environment. One prior effort to manage the heat included utilizing an external water spray boiler to achieve heat dissipation, but a specialized heat exchanger, controller and an on-board source of water are all required. Such a complicated system inherently imposes several undesirable effects, including additional weight and reduced efficiency of the overall system.
According to one embodiment, an oil cooling arrangement includes a first manifold. Also included is a second manifold, wherein the first manifold and the second manifold are each configured to route an oil. Further included is a first tube having a first end proximate the first manifold and a second end proximate the second manifold, wherein the first tube is configured to receive the oil and route the oil toward the second manifold. Yet further included is a second tube having a third end proximate the second manifold and a fourth end proximate the first manifold, wherein the second tube is configured to route the oil from the second manifold toward the first manifold. Also included is a turbine exhaust path configured to route an exhaust flow, wherein the first tube and the second tube are disposed along the turbine exhaust path, wherein the oil is cooled upon passage of the exhaust flow over the first tube and the second tube.
According to another embodiment, a method of cooling oil is provided. The method includes supplying an oil to a first manifold of an oil cooling arrangement. The method also includes routing the oil through a first tube from the first manifold to a second manifold, wherein the first tube is disposed in a turbine exhaust path. The method further includes routing the oil through a second tube from the second manifold to the first manifold, wherein the second tube is disposed in the turbine exhaust path. The method yet further includes flowing an exhaust flow through the turbine exhaust path and over the first tube and the second tube for cooling the oil routed therein.
The subject matter which is regarded as the invention is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
Referring to
The turbine system 14 includes at least one turbine nozzle 16 configured to distribute a propellant fuel 18 to the turbine system 14. In an exemplary embodiment, the propellant fuel 18 is a cold gas, such as helium or hydrogen gas, for example. Irrespective of the precise fuel employed, the propellant fuel 18 drives a turbine wheel 20 and the mechanical power is converted to a desired power type. Subsequent to passing over and driving the turbine wheel 20, the propellant fuel 18, and any air mixed therewith, is routed through an exhaust housing 22 as an exhaust flow 24. The interior region defined by the exhaust housing 22 is referred to as a turbine exhaust path 26. The illustrated embodiment is shown with a shipping port cover 28 proximate an exhaust outlet 30. By employing the cold gas in the space vacuum environment, the exhaust flow 24 passing through the turbine exhaust path 26 is cold, relative to temperatures of operating environments for adjacent components and systems, such as a component or system employing the oil 12 described above. In one embodiment, the temperature of the exhaust flow 24 ranges from about −100° F. (about −73° C.) to about −200° F. (about −129° C.).
The oil cooling arrangement 10 is operatively coupled at a plurality of locations with the turbine system 14. Specifically, the oil cooling arrangement 10 is at least partially disposed within the turbine exhaust path 26 and coupled at an interior location of the exhaust housing 22. Additionally, as illustrated, the oil cooling arrangement 10 is coupled to an exterior surface 32 of the exhaust housing 22, such as with a plurality of mechanical fasteners 34. The oil cooling arrangement 10 comprises a plurality of tubes 36 predominantly or fully disposed within the exhaust housing 22 along the turbine exhaust path 26. In one embodiment, the plurality of tubes 36 comprises a first tube 38, a second tube 40, a third tube 42 and a fourth tube 44. Each of the plurality of tubes 36 extends between and is fluidly coupled with a first manifold 46 and a second manifold 48 at respective ends of each of the plurality of tubes 36. The first manifold 46 is operatively coupled to the exhaust housing 22 and is disposed proximate the exhaust housing 22. In the exemplary embodiment, the first manifold 46 is disposed partially or fully at an exterior region to the turbine exhaust path 26. Integrally formed with, or operatively coupled to, the first manifold 46 is a cover member 50 that includes an inlet 52 and an outlet 54 for receiving and expelling the oil 12 relative to the oil cooling arrangement 10. The second manifold 48 is disposed fully within the turbine exhaust path 26 and is operatively coupled to the turbine system 14 therein.
Referring now to
Integrally formed with the thermal control valve 58 is a pressure relief valve 60 that detects a pressure within passages of the oil cooling arrangement 10. The pressure relief valve 60 is configured to alter the cross-sectional area of one or more passages proximate the inlet 52 and/or outlet 54, thereby increasing the volumetric flow rate of the oil 12 in the event of a partial blockage due to oil clotting or the like. In one embodiment, the pressure relief valve 60 initiates relief at about pressure differential of about 25 psid (about 172 kPa differential).
Referring now to
While flowing through the plurality of tubes 36, which are disposed within the turbine exhaust path 26, the oil 12 is cooled due to heat transfer associated with the exhaust flow 24 passing over an outer surface 68 of the plurality of tubes 36. As described above, the exhaust flow 24 is relatively cold and is therefore suitable for cooling of the oil 12 flowing within the plurality of tubes 36. To enhance the heat transfer to the plurality of tubes 36 from the exhaust flow 24, a plurality of fins 70 extend outwardly from the outer surface 68 of the plurality of tubes 36 to increase the surface area in contact with the exhaust flow 24. To further ensure adequate cooling of the oil 12, at least one rod 72 is disposed within each of the plurality of tubes 36 to form an annulus 76 through which the oil 12 flows. Formation of the annulus 76 causes the oil 12 to flow through the plurality of tubes 36 at regions in close proximity to an inner surface 78 of the plurality of tubes 36, thereby increasing the beneficial cooling effects of the exhaust flow 24. Additionally, the rod 72 includes a machined surface that may include various features to increase turbulence of the oil flow, thereby enhancing cooling of the oil 12 while flowing within the annulus 76. Specifically, the machined surface of the rod 72 may include a knurled surface, for example.
A method of cooling oil 100 is also provided, as illustrated in
Advantageously, the oil cooling arrangement 10 and the method of cooling oil 100 simplifies the heat exchanger structure with higher reliability by enhancing the cooling capability of the structure. Additionally, elimination of an on-board water source that constitutes unnecessary mass is achieved. The reduction in mass provides the opportunity to increase payload mass or reduce fuel consumption.
While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This invention was made with Government support under contract NNM07AB03C awarded by NASA. The Government has certain rights in the invention.