Patent Description:
Aircraft engines are increasingly incorporating electric devices that increase the number and magnitude of heat loads that require management. Heat exchangers are employed that utilize fuel as a heat sink. Air and lubricant are cooled for use in various different engine systems by the fuel. The size and thermal transfer efficiency of a heat exchanger can impact engine design and performance.

Turbine engine manufacturers continue to seek further improvements to engine performance including improvements to thermal transfer efficiencies. For example, <CIT> describes a heat exchanger which includes a first side of a heat exchanger layer with a first flow path for a coolant. The first flow path flows through a heat soak region and a flow region. The heat exchanger also includes a second side of the heat exchanger layer with a second flow path for a fluid to be cooled. The second flow path is in thermal communication with the first flow path, and an inlet of the first flow path and an inlet of the second flow path are proximate in the heat soak region.

A heat exchanger for a gas turbine engine according to an aspect of the present invention has the features of claim <NUM>.

In an embodiment of any of the above embodiments, a direction of a flow of the coolant medium through the first cool portion is counter to a direction of a first hot flow in the first cool portion.

In an embodiment of any of the above embodiments, the more spacer bars in the first cool portion than the second cool portion defines more parallel turning passes in the first cool portion than the second cool portion.

In an embodiment of the above embodiment, a mitered portion including an angled interface with a corresponding channel defines each turning pass.

In an embodiment of any of the above embodiments, the first inlet and the first outlet of the second plate are on a side of the second plate opposite the second inlet and the second outlet.

In an embodiment of any of the above embodiments, each of the first plate and the second plate include passages or channels defining a path of fluid flow and the passages or channels have a herringbone pattern wherein a herring bone pattern is a wavy pattern of walls that increases a surface area for thermal transfer through the first and second plates.

In an embodiment of any of the above embodiments, the coolant medium comprises fuel.

In an embodiment of any of the above embodiments, the coolant medium comprises one of a hydraulic fluid, refrigerant and/or airflow.

In an embodiment of any of the above embodiments, the flow of air is communicated through first hot portion and the flow of oil is communicated through the second hot portion.

In an embodiment of any of the above embodiments, a plurality of first plates and a plurality of second plates alternate such that each of the plurality of second plates is disposed between a pair of the plurality of first plates.

In an embodiment of any of the above embodiments, each of the plurality of first plates are orientated such that each coolant inlet and each coolant outlet for each of the plurality of first plates are disposed on a common side.

A thermal management system for a gas turbine engine according to an aspect of the present invention has the features of claim <NUM>.

Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations.

<FIG> schematically illustrates a gas turbine engine <NUM> for powering an aircraft. Although depicted as a two-spool turbofan gas turbine engine in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with two-spool turbofans as the teachings may be applied to other types of turbine engines including but not limited to three-spool architectures.

It should be understood that the various bearing systems <NUM> may alternatively or additionally be provided at different locations, and the location of bearing systems <NUM> may be varied as appropriate to the application.

The inner shaft <NUM> is connected to a fan section <NUM> through a speed change mechanism, which in exemplary gas turbine engine <NUM> is illustrated as a geared architecture <NUM> to drive fan blades <NUM> at a lower speed than the low speed spool <NUM>.

The turbines <NUM>, <NUM> rotationally drive the respective low speed spool <NUM> and high speed spool <NUM> in response to the expansion of the combustion gases. For example, gear system <NUM> may be located aft of the low pressure compressor <NUM> and the fan blades <NUM> may be positioned forward or aft of the location of the geared architecture <NUM> or even aft of turbine section <NUM>.

In one disclosed embodiment, the engine <NUM> bypass ratio is greater than about ten, the fan diameter is significantly larger than that of the low pressure compressor <NUM>, and the low pressure turbine <NUM> has a pressure ratio that is greater than about five (<NUM>:<NUM>). The low pressure turbine <NUM> pressure ratio is pressure measured prior to the inlet of low pressure turbine <NUM> as related to the pressure at the outlet of the low pressure turbine <NUM> prior to an exhaust nozzle. It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present invention is applicable to other gas turbine engines including but not limited to direct drive turbofans.

The majority of the thrust is provided by the bypass flow B due to the high bypass ratio. The flight condition of <NUM> Mach and <NUM>,<NUM> ft (<NUM>,<NUM>), with the engine at its best fuel consumption - also known as "bucket cruise Thrust Specific Fuel Consumption ('TSFC')" - is the industry standard parameter of lbm of fuel being burned divided by lbf of thrust the engine produces at that minimum point. The low fan pressure ratio as disclosed herein according to one non-limiting embodiment is less than about (<NUM>:<NUM>). "Low corrected fan tip speed" is the actual fan tip speed in ft/sec divided by an industry standard temperature correction of [(Tram °R) / (<NUM> °R)] <NUM> (where °R = K x <NUM>/<NUM>). The "Low corrected fan tip speed" as disclosed herein according to one non-limiting embodiment is less than about <NUM> ft/s (<NUM>/s).

The example gas turbine engine includes the fan section <NUM> that comprises in one non-limiting embodiment less than about <NUM> fan blades <NUM>. In another non-limiting embodiment, the fan section <NUM> includes less than about <NUM> fan blades <NUM>. Moreover, in one disclosed embodiment the low pressure turbine <NUM> includes no more than about <NUM> turbine rotors schematically indicated at <NUM>. In another disclosed embodiment, the low pressure turbine includes about <NUM> rotors. In another non-limiting example embodiment, the low pressure turbine <NUM> includes about <NUM> turbine rotors. In yet another disclosed embodiment, the number of turbine rotors for the low pressure turbine <NUM> may be between <NUM> and <NUM>. A ratio between the number of fan blades <NUM> and the number of low pressure turbine rotors is between about <NUM> and about <NUM>. The example low pressure turbine <NUM> provides the driving power to rotate the fan section <NUM> and therefore the relationship between the number of turbine rotors <NUM> in the low pressure turbine <NUM> and the number of blades <NUM> in the fan section <NUM> disclose an example gas turbine engine <NUM> with increased power transfer efficiency.

A fuel system <NUM> delivers fuel from a fuel tank <NUM> to the combustor <NUM>. Fuel provides a favorable medium for transference of thermal energy because the resulting preheated fuel provides for increased combustor efficiency. A portion of fuel from the fuel system <NUM> is provided to a thermal management system (TMS) <NUM> for use as heat sink to absorb heat from other engine systems. Other engine systems can include a buffer air system and/or environmental control systems schematically indicated at <NUM>. The engine systems may include a lubrication system a schematically indicated at <NUM>. Lubricant flows and air flows are cooled by the TMS <NUM> to maintain temperatures within predefined limits. The example TMS <NUM> may include various passages, filters, screens, pressure sensors, temperature sensors, valves, and pumps to communicate the hot flows into thermal communication with a coolant. In this example, the fuel system <NUM> provides the fuel flow for use as a coolant. In other examples, other suitable media can be used as a coolant, such as single-phase flow media (e.g., hydraulic fluid) and/or two-phase flow media (e.g., refrigerants, water, refrigerant/water mixtures, etc.). As appreciated, although not shown, temperature sensors may be used to detect temperatures in the hot flows and in the coolant. Furthermore, as appreciated, although not shown, these detected temperatures signals may be sent to on-board controllers (e.g., Electronic Engine Control-EEC/Full Authority Digital Engine Control-FADEC) which, in turn, may provide control outputs to various TMS components, thus allowing the TMS <NUM> to maintain said predefined temperature limits in hot flows and in coolant. The TMS <NUM> includes a heat exchanger <NUM> that places hot flows in thermal communication with the coolant. An example disclosed embodiment includes at least one heat exchanger <NUM> that provides for cooling of several hot flows within a single compact structure. As is appreciated, one or several heat exchangers <NUM> could be included to place a coolant flow (e.g., fuel) into thermal communication with hot flows (e.g., lubricant flow and air flow) that require cooling.

Referring to <FIG> and <FIG>, the example heat exchanger <NUM> places a coolant into thermal communication with more than one hot flow. In this disclosed example, a lubricant flow <NUM> and an air flow <NUM> are cooled by a fuel flow <NUM>. The example heat exchanger <NUM> includes a first plate <NUM> for the coolant flow, fuel in this example, and a second plate <NUM> for the flows to be cooled, lubricant and air in this example. The first and second plates <NUM>, <NUM> are stacked against each other to provide thermal communication. The plates <NUM>, <NUM> are formed as separate parts and multiple ones of the first and second plates <NUM>, <NUM> are assembled together to provide a desired flow capacity of the heat exchanger <NUM>.

The plates <NUM>, <NUM> may be formed as cast metal material or from a plastic material compatible with the temperature ranges of the flows. The plates <NUM>, <NUM> may be machined from metal material. The plates <NUM>, <NUM> may be formed using molding or additive manufacturing methods as well as other known manufacturing and forming processes.

Each of the plates <NUM>, <NUM> includes a plurality of passages or channels <NUM> (hereafter referred to as "channels") that define a flow path for the corresponding flows. The channels <NUM> are shown in a herringbone pattern. The herringbone pattern is a wavy pattern of walls that increases a surface area for thermal transfer through the plates <NUM>, <NUM>. The channels <NUM> may be formed in other patterns that accentuate thermal transfer between the coolant and hot flows.

Spacer bars <NUM> are provided within each of the plates <NUM>, <NUM> to define a direction of flow through the channels. The spacer bars <NUM> also define the number of passes that each flow will make for a defined area. The more passes of flow in a defined area, the more thermal transfer that occurs.

The number of passes defined by the spacer bars in the example plates <NUM> is varied to tailor thermal transfer to application specific requirements. In the disclosed example, the first plate <NUM> includes a first cool portion <NUM> and a second cool portion <NUM>. The first cool portion <NUM> includes a width <NUM> and a length <NUM> that define a first flow area. The second cool portion <NUM> includes a width <NUM> and a length <NUM> that defines a second flow area.

The first cool portion <NUM> includes more spacer bars <NUM> than is provided in the second cool portion <NUM> such that the first cool portion <NUM> includes more passes of the fuel coolant. The increased number of passes also means that fuel is within the first cool portion <NUM> for a longer duration than fuel flow in the second cool portion <NUM>. The increased or greater duration of fuel time in the first cool portion <NUM> provides different rates of thermal transfer in the different portions <NUM>, <NUM>.

The disclosed second plate <NUM> includes a first hot portion <NUM> that is in thermal communication with the first cool portion <NUM> of the first plate <NUM>. A second hot portion <NUM> of the second plate <NUM> is in thermal communication with the second cool portion <NUM> of the first plate <NUM>. In this example, the first hot portion <NUM> receives an airflow <NUM> through an inlet <NUM>. The first hot portion <NUM> includes the channels <NUM> and spacer bars <NUM> to define a number of passes the airflow <NUM> takes before exiting through the outlet <NUM>.

The first hot portion <NUM> includes a length <NUM> and a width <NUM> that define an area for the airflow <NUM> and for thermal transfer with the coolant flow in the first plate <NUM>. In this example, an area of the first hot portion <NUM> and an area of the first cool portion <NUM> are the same. Similarly, the second hot portion <NUM> includes a width <NUM> and a length <NUM> that define and area for thermal transfer with coolant in the second cool portion <NUM>. In this example, the second hot portion <NUM> receives a lubricant flow <NUM> through an inlet <NUM>. The second hot portion <NUM> includes the channels <NUM> and spacer bars <NUM> to define a number of passes the lubricant flow <NUM> takes before exiting through the outlet <NUM>. The area of the second cool portion <NUM> and the second hot portion <NUM>, in this example are the same. It should be appreciated that different relative areas between the first plate <NUM> and the second plate <NUM> could be utilized and are within the scope and contemplation of this disclosure.

The increased number of passes defined by the example first hot portion <NUM> and the first cool portion <NUM> provide a different rate of thermal transfer between the airflow <NUM> and the fuel flow <NUM> as compared to the a rate of thermal transfer between lubricant flow <NUM> and the fuel flow <NUM>. The amount of thermal transfer into the fuel within the first hot portion is increased due to the increased amount of time the fuel is present within the first cool portion <NUM>. Fuel flow from the first cool portion <NUM> flows into the second cool portion <NUM> and absorbs additional thermal energy from the lubricant flow <NUM>.

In the disclosed example first plate <NUM> the spacer bars <NUM> in the first cool portion <NUM> are transverse to the spacer bars <NUM> disposed in the second cool portion <NUM>. The different flow directions are defined to provide a desired resident time within each portion <NUM>, <NUM> to tailor thermal transfer to application specific requirements. The first plate <NUM> provides the inlet <NUM> and the outlet <NUM> on a common side to simplify assembly.

The second plate <NUM> includes spacer bars <NUM> that are all parallel to each other to define parallel paths for lubricant flow <NUM> and the airflow <NUM>. In this disclosed example, the coolant flow in the first cool portion <NUM> is counter to the airflow <NUM> in the first hot portion <NUM>. The flow of fuel <NUM> in the second cool portion <NUM> is transverse to lubricant flow <NUM> in the second hot portion <NUM>. The direction of flows is disclosed by way of example and may be provided in different relative directions within the scope and contemplation of this disclosure.

A mitered portion <NUM> defines a transition between passes of each flow between the spacer bars <NUM>. Each of the mitered portions <NUM> include channels <NUM> to aid in thermal transfer. The mitered portions <NUM> contain the transition between the different passes within each of the plates <NUM>, <NUM> to simplify the structure and assembly of the heat exchanger <NUM>.

Referring to <FIG>, with continued reference to <FIG>, the heat exchanger <NUM> is scalable to accommodate different thermal transfer and cooling requirements. The first and second plates <NUM>, <NUM> are stacked in an alternating manner such that each of the second plates <NUM> are disposed between one of the first plates <NUM>. The plates <NUM>, <NUM> are stacked such that all of the inlets and outlet for a specific flow are aligned on a common side. In this example, all the air inlets <NUM> and air outlets <NUM> are on one side and all of the lubricant inlets <NUM> and outlets <NUM> are on an opposite side. All the inlets <NUM> and the outlets <NUM> for the fuel are provided on a common side. Suitable piping and conduits would be provided to communicate each flow (e.g., fuel flow <NUM>, lubricant flow <NUM>, and air flow <NUM>) from the corresponding system to and from the heat exchanger <NUM>.

The example heat exchanger <NUM> incorporates several flows for cooling into a common assembly and is configurable to tailor thermal transfer to the temperatures of each individual flow.

Claim 1:
A heat exchanger (<NUM>) for a gas turbine engine (<NUM>) comprising:
a first plate (<NUM>) for a coolant medium, the first plate (<NUM>) including a first cool portion (<NUM>), a second cool portion (<NUM>), a coolant inlet (<NUM>) and a coolant outlet (<NUM>), the coolant inlet (<NUM>) and the coolant outlet (<NUM>) disposed on a common side, and
a second plate (<NUM>) in thermal communication with the first plate (<NUM>),
each of the plates (<NUM>, <NUM>) includes a plurality of channels (<NUM>) that define a flow path for the corresponding flows,
spacer bars (<NUM>) are provided within each of the plates (<NUM>, <NUM>) to define a direction of flow through the channels, the spacer bars (<NUM>) also define the number of passes that each flow will make for a defined area,
the first cool portion (<NUM>) includes more spacer bars (<NUM>) than is provided in the second cool portion (<NUM>) such that the first cool portion (<NUM>) includes more passes of the coolant medium than the second cool portion (<NUM>),
the heat exchanger being characterised in that:
the second plate (<NUM>) includes a first hot portion (<NUM>) including a first inlet (<NUM>) for a flow of air and a first outlet (<NUM>) and a second hot portion (<NUM>) including a second inlet (<NUM>) for a flow of lubricant and a second outlet (<NUM>), wherein the first cool portion (<NUM>) is in thermal communication with the first hot portion (<NUM>) and the second cool portion (<NUM>) is in thermal communication with the second hot portion (<NUM>);
wherein the first hot flow comprises a flow of air and the second hot flow comprises a flow of oil; and
the first cool portion (<NUM>) and the first hot portion (<NUM>) have a common width (<NUM>, <NUM>) and a common length (<NUM>, <NUM>) in parallel planes.