Patent Application
20170074167
The present invention relates to a precooler system for use with a turbofan engine, and more particularly to a turbofan engine mounted precooler system.
Turbofan engines are often configured to divert a portion of high-energy compressed air (generally from a compressor section of the turbofan engine) for use in other aircraft systems. The diverted compressed engine air may be supplied to aircraft systems, such as an aircraft environmental control system (ECS), an aircraft anti-ice system, and the like. To minimize the chance of fires due to hot surface ignition within the fuselage of the aircraft, the high temperature compressor bleed air is cooled by lower temperature fan bleed air. The diverted air is typically cooled by a precooler or heat exchanger (referred to herein as a precooler) prior to its introduction to the fuselage in aircraft with fuselage mounted engines. However, determining where to locate the precooler with respect to the turbofan engine in these installations is not straightforward.
Locating a precooler proximate a turbofan engine is desirable but traditionally untenable. Turbofan engines are generally surrounded by a nacelle that provides a smooth outer cover, and creates a bounded space within which the turbofan engine operates. In traditional turbofan engine designs, the space between the turbofan engine and the nacelle is limited and generally consumed by other turbofan engine systems. Consequently, in all but the largest of turbofan engines, space and weight considerations often drive the disposition of the precooler to locations remote from the turbofan engine, such as within the pylon. Additional ducting and components may then then be required for routing the engine air to and from the precooler. However, the additional ducting and components may add weight and cost to the aircraft, a generally undesirable result as the demand for more economical aircraft continues to increase. Additionally, disposing of the precooler in the pylon requires the precooler system to have separate right hand and left hand permutations, and prohibits that pylon space to be used for other aircraft systems and devices. The separate left hand and right hand precooler system increases part count, and part cost.
Hence, there is a need for a non-handed precooler system having a symmetric precooler core that is optimized to be integrally mounted to the turbofan engine, regardless of the turbofan engine size. The desired precooler system optimizes available space between a turbofan engine and the nacelle, and does not substantially increase weight and cost. The present invention provides these features.
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
A precooler system is provided. The precooler system comprising:
a nacelle;
a turbofan engine housed within the nacelle, the turbofan engine configured to discharge engine air and bypass air; the turbofan engine comprising a bypass duct providing a path for the bypass air;
a high pressure shut off valve (HPSOV) coupled to the turbofan engine;
a pressure regulating shut off valve (PRSOV) coupled to the turbofan engine and to the HPSOV; wherein the HPSOV and PRSOV are each (i) located within the same turbofan engine stage, and (ii) configured to cooperatively regulate pressure of engine air; and a symmetrical precooler core disposed outside of the bypass duct, integrally mounted in an opening in the nacelle, and forming a substantially continuous outer wall of the bypass duct, the symmetrical precooler core comprising (i) a first flow passage having an engine air inlet and an engine air outlet, the first flow passage being in flow communication with engine air at the engine air inlet and discharge air at the engine air outlet, and (ii) a second flow passage having bypass flow path inlet and a bypass flow path outlet and being in flow communication with bypass air at the bypass flow path inlet and ambient air at the bypass flow path outlet.
Another precooler system is provided. The precooler system comprising:
a turbofan engine configured to discharge engine air and bypass air, the turbofan engine having a bypass duct associated therewith; and
a symmetrical precooler core configured to be integrally mounted in an opening in a nacelle, and disposed outside of the bypass duct, the symmetrical precooler core comprising
the symmetrical precooler core further configured to transfer heat between the first flow passage and the second flow passage.
Also provided is a symmetrical precooler core, the symmetrical precooler core comprising:
a first flow passage having an engine air inlet and an engine air outlet, the first flow passage configured to be in flow communication with engine air at the engine air inlet and with discharge air at the engine air outlet; and
a second flow passage having bypass flow path inlet and a bypass flow path outlet and configured to be in flow communication with bypass air at the bypass flow path inlet and with ambient air at the bypass flow path outlet; and
wherein the symmetrical precooler core is configured to (i) be disposed outside of a turbofan engine bypass duct, (ii) be integrally mounted in an opening in a nacelle, (iii) form a substantially continuous outer wall of the bypass duct.
Other desirable features will become apparent from the following detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
A more complete understanding of the subject matter may be derived by referring to the following Detailed Description and Claims when considered in conjunction with the following figures, wherein like reference numerals refer to similar elements throughout the figures, and wherein:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. As used herein, the word “exemplary” means “serving as an example, instance, or illustration.” Thus, any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.
Although not the focus of the present invention, one with skill in the art will readily appreciate that the traditional turbofan engine comprises multiple sections, in stages. For easy reference in the below detailed description, a simplified description of a traditional turbofan engine with a cooling system is provided as follows.
A traditional turbofan engine is generally enclosed within a nacelle and comprises a fan section, a compressor section, a combustion section, a turbine section, and an exhaust section. The compressor section raises the pressure and increases the temperature of the air directed into it from the fan section. The compressor section may direct the compressed air into the combustion section. In the combustion section, the high pressure air is mixed with fuel and combusted. The combusted air is then directed into the turbine section, wherein it expands through turbines, causing them to rotate, and is then exhausted through a mixer nozzle and combines with air from a bypass duct. At least some compressed air is generally reserved for the aircraft. This is known as customer bleed air. It is generally high pressure and high temperature air that comes from the engine and is sent via ducting to the airframe.
The installation of a traditional turbofan engine in a modern aircraft requires the high pressure compressor discharge air to be cooled prior to its introduction to other sections of the aircraft. In this regard, a cooling system typically includes a precooler. Prior to being sent to the precooler, the high pressure compressor discharge air is generally pressure regulated via several valves and associated ducting. Two of these valves include the high pressure shut off valve (HPSOV) and the pressure regulating shut off valve (PRSOV). The HPSOV selects the compressor stage from which the high pressure air source is retrieved. The PRSOV is generally used to control or modulate the quantity of engine air pressure flow in the ducting being supplied to other aircraft systems.
Together, the HPSOV and PRSOV are configured to cooperatively regulate the pressure of the high pressure, high temperature compressor discharge air subsequently received by the precooler. Accordingly, in some applications, the orientation and location of the HPSOV and PRSOV, with respect to the precooler, are design specific features of a precooler system.
The precooler receives low pressure, low temperature fan discharge air from the engine. This air is used to cool the high pressure, high temperature compressor discharge air to be delivered to other aircraft subsystems located in the fuselage of the aircraft. After passing through the precooler, the low pressure air is discharged overboard. However, the fan discharge airflow is regulated by a fan air valve (FAV). The fan air valve is a modulating flow control system used to minimize the amount of fan air discharged overboard.
The precooler system 206 provides a first flow passage 158 being in flow communication with pressure regulated engine air at an engine air inlet 302 and discharge air at an engine air outlet 304. The precooler system 206 also provides one or more second flow passages 312 having a bypass flow path inlet (
Once through the HPSOV, PRSOV, and associated ducting, the high temperature, compressed, engine air is sufficiently pressure regulated for the precooler at engine air inlet 302. In an embodiment, an engine air supply duct 154 supplies compressed, high temperature engine air to the precooler system 206. Although shown as a pipe, the engine air supply duct 154 and duct 156 may alternatively be any structure suitable for delivering air to the precooler system 206.
The precooler core (
In the embodiment, precooler system 206 is disposed outside of the bypass duct 214 and mounted in an opening 216 in the nacelle 100. Ambient air 204 moves from the forward side 104 toward the aft side 102. Air in the bypass duct 302 is at a higher pressure that the ambient air 204. This makes it possible for cooling flow to pass through the pre-cooler releasing heated air from the second flow passage 312 into ambient air 204.
By disposing the precooler system 206 outside of the bypass duct 214, and integrally mounting the precooler system 206 into an opening 216 in the nacelle 100, in some embodiments, air may flow directly between the bypass duct 214 and the precooler system 206, without requiring any additional ducting. Additionally, the provided precooler system 206 design may coordinate with a HPSOV 150 and PRSOV 152 that are each located within the space between the turbofan engine 107 and the nacelle 100 (stage 155), further optimizing turbofan engine 107 space and weight.
When mounted to the nacelle 100, the integrally mounted precooler system 206 provides a smooth outer surface 316 that is substantially continuous with the outer surface of nacelle 100. In an embodiment, precooler system 206 may comprise a plate 308, surrounded by a seal 310, the combination of which is configured to be integrally mounted into an appropriately sized opening 216 in nacelle 100, and forming a portion of the outer surface of the nacelle 100. In other embodiments, the precooler core 305 has a surface sufficient to be integrally mounted into an appropriately sized opening 216 in the nacelle 100 and provide a smooth outer surface 316 that is substantially continuous with the outer surface of nacelle 100.
The arrangement of cross tubes 406, their dimensions, and their composition are selected to maximize heat exchanging surface area as the movement of air in the second flow passages 312 travels across them, cooling the cross tubes 406 as it does so. In the exemplary embodiment, the cross tubes 406 are stabilized within the precooler core 305 via a support structure. An exemplary support structure is described in connection with
As may be readily appreciated, surface area is the key to effective heat transfer, and each additional cross tube 406 provides increased surface area for heat transfer. However, as surface area is increased, size, weight, and cost typically increase, forcing individual design applications to optimize the benefits of increased surface area with the tradeoffs. In an embodiment, the cross tubes 406 have a diameter from about ⅛ of an inch to about ¼ of an inch, and there are about ten cross tubes 406.
For example, support structure 500 may be used to define an arrangement of cross tubes such that each cross tube 406 in the arrangement of cross tubes extends from the engine air inlet 302 to the engine air outlet 304. In the embodiment, support structure 500 comprises a first wall 505 and a second wall 507, each wall having a plurality of holes therethrough. The plurality of holes is arranged such that, when populated by cross tubes 406, the arrangement forms one or more air deflection paths to assist in heat exchange in the second flow passage 312. In the embodiment, the plurality of holes is arranged in groups 504 of holes, each of the groups 504 forming a slight arc in the same direction. In the embodiment each group 504 of holes includes four holes; however, the number of holes in the plurality of holes and the number of holes in each group 504 is design specific.
The support structure 500 may further comprise one or more deflector slats 502 coupled within the support structure 500 and oriented to deflect bypass air 202 and to assist in heat exchange through the second flow passage 312. Accordingly, in some embodiments, the support structure 500 may rely on an arrangement of the cross tubes 406 to deflect air, and in other embodiments, the support structure 500 may additionally rely on deflector slats 502 for deflecting air. Although the support structure 500 is shown as comprising a first wall 505 and a second wall 507, each wall having a plurality of holes therethrough, a variety of other configurations may be implemented to accomplish the same objective without straying from the scope of the invention.
As one with skill in the art will appreciate, the blocking functionality may be implemented in a variety of ways. In the embodiment, louvers 802 are each attached to the precooler core 305 with moveable fasteners 804. The size, material and dimension of the louvers 802 and moveable fasteners 804 are application specific. In
Thus, there has been provided a precooler system having a precooler core that is optimized to be integrally mounted to the turbofan engine, regardless of the turbofan engine size. The provided precooler system optimizes available space between a turbofan engine and the nacelle, and does not substantially increase weight and cost. The provided precooler system may be flexibly implemented as either a right handed precooler system or a left handed precooler system.
While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention. It being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
In this document, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Numerical ordinals such as “first,” “second,” “third,” etc. simply denote different singles of a plurality and do not imply any order or sequence unless specifically defined by the claim language. The sequence of the text in any of the claims does not imply that process steps must be performed in a temporal or logical order according to such sequence unless it is specifically defined by the language of the claim.
Furthermore, depending on the context, words such as “connect” or “coupled to” used in describing a relationship between different elements do not imply that a direct physical connection must be made between these elements. For example, two elements may be connected to each other physically, electronically, logically, or in any other manner, through one or more additional elements.
Some of the embodiments and implementations are described above in terms of functional and/or logical block components or modules. However, it should be appreciated that such block components (or modules) may be realized by any number of hardware, software, and/or firmware components configured to perform the specified functions. To clearly illustrate this interchangeability of hardware and software, these illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
