Air-to-air heat exchanger potential in gas turbine engine

Abstract

A gas turbine engine is provided. The gas turbine engine includes a compressor section, a combustion section, and a turbine section in a series flow arrangement; and an air-to-air heat exchanger having an air-to-air heat exchanger potential, the air-to-air heat exchanger potential defined by a half power of a product, the product being an effectiveness associated with the air-to-air heat exchanger multiplied by an airflow conductivity coefficient associated with the gas turbine engine, and wherein the air-to-air heat exchanger potential is between 0.028 and 0.067 for a bypass ratio between 3 and 10 and an effectiveness between 0.5 and 0.9 associated with the gas turbine engine, and the air-to-air heat exchanger potential is between 0.015 and 0.038 for a bypass ratio between 10 and 20 and an effectiveness between 0.3 and 0.9 associated with the gas turbine engine.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application is a continuation-in-part of U.S. application No. 17 / 706,814, filed on March 29, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to an air-to-air heat exchanger for a gas turbine engine. Background Art

[0004] A gas turbine engine may include one or more heat exchangers, such as one or more air-to-air heat exchangers. Such air-to-air heat exchangers may be configured to use relatively cool low-pressure air to cool relatively hot high-pressure air. The cooled high-pressure air may be used to cool certain components, such as bearings and turbine components. A gas turbine engine having an air-to-air heat exchanger that is compactly arranged and capable of receiving an air flow to efficiently handle a heat load would be a useful addition to the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] A full and enabling disclosure of the present disclosure, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0006] Figure 1 A schematic cross-sectional view of a gas turbine engine according to an example embodiment of the present disclosure is provided;

[0007] Figure 2 A perspective view of a heat exchanger according to an example embodiment of the present disclosure is provided;

[0008] Figure 3 Provided Figure 2 A perspective view of an exchanger unit of a heat exchanger;

[0009] Figure 4 Provides along Figure 3 A cross-sectional view of the core of the exchanger unit taken along line 4-4;

[0010] Figure 5 A schematic diagram of a heat exchanger coupled to an accessory gearbox of a turbofan engine is provided;

[0011] Figure 6 lists various relationships between heat exchanger characteristics and operational and architectural characteristics of a gas turbine engine according to example embodiments of the present disclosure; and

[0012] Figures 7 to 12graphically depicts an air-to-air heat exchanger potential of an air-to-air heat exchanger in flow communication with a gas turbine engine as a function of a bypass ratio of the gas turbine engine, respectively, according to an example embodiment of the present disclosure;

[0013] Fig.13 A table is provided listing values ​​for four different example gas turbine engines according to example embodiments of the present disclosure; and

[0014] Fig.14 A flow chart of a method of operating a gas turbine engine having a heat exchanger in flow communication therewith is provided according to an example embodiment of the present disclosure. DETAILED DESCRIPTION

[0015] Reference will now be made in detail to the present embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter references to refer to features in the drawings. Like or similar reference numbers in the drawings and description have been used to refer to like or similar parts of the present disclosure.

[0016] As used herein, the terms “first,” “second,” and “third” are used interchangeably to distinguish one component from another, and are not intended to indicate the position or importance of each component.

[0017] Unless otherwise specified herein, the terms "coupled," "fixed," "attached to," and the like refer to both direct coupling, fixing, or attachment as well as indirect coupling, fixing, or attachment through one or more intermediate components or features.

[0018] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0019] In a context such as “at least one of A, B, and C,” the term “at least one of” means only A, only B, only C, or any combination of A, B, and C.

[0020] Here and throughout the specification and claims, range limitations are combined and interchanged, and unless context or language indicates otherwise, such ranges are identified and include all sub-ranges contained therein. For example, all ranges disclosed herein (including those using the term "between", e.g., "between A and B") include the endpoints, and the endpoints are independently combinable with each other.

[0021] Some gas turbine engines may include one or more heat exchangers. For example, a gas turbine engine may include an air-to-air heat exchanger that is configured to cool relatively hot high-pressure air using relatively cool low-pressure air. The cooled high-pressure air may be used to cool certain components, such as bearings or turbine components of the gas turbine engine. Designing a gas turbine engine with an air-to-air heat exchanger that is both compact and capable of efficiently handling the heat load has been challenging.

[0022] The inventors of the present disclosure have developed an architecture for a gas turbine engine having an air-to-air heat exchanger that is both compact and capable of efficiently handling heat loads. Specifically, the inventors have designed several different types of gas turbine engines (including the Figure 1 During the design of a gas turbine engine described in the specification, the process is performed in the following manner: designing a turbofan engine with given fan, length, total pressure ratio and bypass ratio characteristics and characteristics of an air-to-air heat exchanger connected to the core flow of the engine; checking the compactness and efficiency of the air-to-air heat exchanger taking into account the characteristics of the fan, length, total pressure ratio and bypass ratio and the characteristics of the heat exchanger; redesigning the engine and / or the heat exchanger by changing the fan diameter, length, total pressure ratio and bypass ratio characteristics and operating parameters of the heat exchanger; rechecking the compactness and efficiency of the air-to-air heat exchanger taking into account the characteristics of the fan, length, total pressure ratio and bypass ratio and the characteristics of the heat exchanger; and so on.

[0023] In the practice of researching / evaluating various fans, lengths, overall pressure ratios, bypass ratios, and heat exchanger characteristics that were considered feasible to best meet mission requirements, an unexpected relationship was discovered between the effectiveness of a heat exchanger and the ease with which airflow can be supplied to the heat exchanger. This relationship is represented by the air-to-air heat exchanger potential. The air-to-air heat exchanger potential can be considered an indicator of the effectiveness of the heat exchanger in handling a heat load, taking into account the architectural arrangement of the gas turbine engine and the architectural / operating arrangement of the air-to-air heat exchanger. The inventors have discovered that a gas turbine engine having an air-to-air heat exchanger presents a heat exchanger that is both compact and effective in handling heat loads, the air-to-air heat exchanger having an air-to-air heat exchanger potential within the ranges specified herein.

[0024] Now referring to the accompanying drawings, Figure 1 A schematic cross-sectional view of a gas turbine engine 100 is provided in accordance with an example embodiment of the present disclosure. Figure 1In the illustrated embodiment, the gas turbine engine 100 is an aviation high bypass turbofan jet engine configured to be mounted to an aircraft, for example, in an underwing configuration. As shown, the gas turbine engine 100 defines an axial direction A, a radial direction R, and a circumferential direction C. The axial direction A extends parallel to or coaxially with a longitudinal centerline 102 defined by the gas turbine engine 100.

[0025] The gas turbine engine 100 includes a fan section 104 and an engine core 106 disposed downstream of the fan section 104. The engine core 106 includes an engine cowling 108 defining an annular core inlet 110. The engine cowling 108 surrounds a compressor section 112, which includes a first supercharger or LP compressor 114 and a second HP compressor 116, a combustion section 118, a turbine section 120, which includes a first HP turbine 122 and a second LP turbine 124, and an exhaust section 126 in series flow relationship. An HP shaft 128 drivingly connects the HP turbine 122 to the HP compressor 116. An LP shaft 130 drivingly connects the LP turbine 124 to the LP compressor 114. The compressor section 112, the combustion section 118, the turbine section 120, and the exhaust section 126 together define a core air flow path 132 through the engine core 106.

[0026] The fan section 104 includes a fan 134 having a plurality of fan blades 136 coupled to a disk 138 in a circumferentially spaced manner. As shown, the fan blades 136 extend outwardly from the disk 138 generally along a radial direction R. For this embodiment, each fan blade 136 is capable of rotating about a pitch axis P relative to the disk 138 by means of the fan blades 136 being mechanically coupled to an appropriate actuating member 140, the actuating member 140 being configured to, for example, collectively change the pitch of the fan blades 136 in unison. The fan blades 136, the disk 138, and the actuating member 140 are together capable of rotating about the longitudinal centerline 102 through the LP shaft 130 across a power gearbox 142. The power gearbox 142 includes a plurality of gears for reducing the rotational speed of the LP shaft 130 to provide a more efficient fan speed. In other embodiments, the fan blades 136, the disk 138, and the actuating member 140 may be directly connected to the LP shaft 130, for example, in a direct drive configuration. Furthermore, in other embodiments, fan blades 136 of fan 134 may be fixed pitch fan blades.

[0027] Still reference Figure 1, the disk 138 is covered by a rotatable spinner 144 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 136. In addition, the fan section 104 includes an annular fan case or outer nacelle 146 that circumferentially surrounds the fan 134 and / or at least a portion of the engine core 106. The nacelle 146 is supported relative to the engine core 106 by a plurality of circumferentially spaced outlet guide vanes 148. A downstream section 150 of the nacelle 146 extends over an outer portion of the engine core 106 to define a bypass airflow passage 152 therebetween.

[0028] During operation of gas turbine engine 100, a volume of air 154 enters gas turbine engine 100 through nacelle 146 and / or associated inlet 156 of fan section 104. As volume of air 154 passes through fan blades 136, a first portion of air 158 is directed or directed into bypass airflow passage 152, and a second portion of air 160 is directed or directed into core inlet 110. The pressure of second portion of air 160 gradually increases as it flows downstream through LP compressor 114 and HP compressor 116. In particular, LP compressor 114 includes sequential stages of LP compressor stator vanes 182 and LP compressor blades 184 that progressively compress second portion of air 160. LP compressor blades 184 are mechanically coupled to LP shaft 130. Similarly, HP compressor 116 includes sequential stages of HP compressor stator vanes 186 and HP compressor blades 188 that further progressively compress second portion of air 160. HP compressor blades 188 are mechanically coupled to HP shaft 128. The compressed second portion of air 160 is then discharged from the compressor section 112 into the combustion section 118 .

[0029] The compressed second portion of air 160 discharged from the compressor section 112 is mixed with fuel and combusted within the combustor of the combustion section 118 to provide combustion gases 162. The combustion gases 162 are directed from the combustion section 118 along a hot gas path 174 of the core air flow path 132 through the HP turbine 122, where a portion of the thermal and / or kinetic energy from the combustion gases 162 is extracted via sequential stages of HP turbine stator vanes 164 and HP turbine blades 166. The HP turbine blades 166 are mechanically coupled to the HP shaft 128. Thus, as the HP turbine blades 166 extract energy from the combustion gases 162, the HP shaft 128 rotates, thereby supporting the operation of the HP compressor 116. The combustion gases 162 are directed through the LP turbine 124, where a second portion of the thermal and kinetic energy is extracted from the combustion gases 162 via sequential stages of LP turbine stator vanes 168 and LP turbine blades 170. The LP turbine blades 170 are coupled to the LP shaft 130. Thus, as the LP turbine blades 170 extract energy from the combustion gases 162 , the LP shaft 130 rotates, thereby supporting the operation of the LP compressor 114 and the fan 134 .

[0030] The combustion gases 162 are then directed through the exhaust section 126 of the engine core 106 to provide propulsive thrust. At the same time, the pressure of the first portion of air 158 is significantly increased as it is directed through the bypass airflow passage 152 before being discharged from the fan nozzle exhaust section 172 of the gas turbine engine 100, which also provides propulsive thrust. The HP turbine 122, the LP turbine 124, and the exhaust section 126 at least partially define a hot gas path 174 for directing the combustion gases 162 through the engine core 106.

[0031] Still refer to Figure 1 , it should be understood that the turbofan engine 10 defines an engine length L. As used herein, the engine length L refers to the length between the forward tip of the rotatable spinner 144 and the rear flange 143 of the gas turbine engine 100 along the axial direction A. The rear flange 143 refers to a circumferential flange near the rear end of the gas turbine engine 100 for coupling the tail cone 141 to the rest of the gas turbine engine 100.

[0032] In addition, it should be understood that the gas turbine engine 100 defines an overall pressure ratio OPR. As used herein, the term overall pressure ratio OPR refers to the pressure of the gas flow at the outlet of the compressor section (e.g., at a location immediately downstream of the most downstream stage of the compressor rotor blades of the HP compressor 116) and the pressure of the gas flow provided to the turbine (e.g., at Figure 1The overall pressure ratio OPR is measured while operating the gas turbine engine 100 to operate the high pressure spool of the turbofan engine at one hundred percent capacity (100%).

[0033] It is noteworthy that, as used herein, operating the high voltage spool at 100% capacity or at maximum speed refers to an operating condition of a gas turbine engine in which the high voltage spool of the gas turbine engine is operated at a speed corresponding to its 100% spool speed capacity. The 100% spool speed capacity is a spool operating condition that may occur during a takeoff operating condition, a maximum power cruise operating condition, or other high power operating condition. In some configurations, the 100% spool speed operating condition may be less than the redline operating speed of the spool.

[0034] like Figure 1 As further shown, the gas turbine engine 100 includes a cooling system 190 for cooling various components, such as bearings 180. The cooling system 190 includes one or more heat exchangers, such as a heat exchanger 192. The heat exchanger 192 may be, for example, a buffer air heat exchanger (BAHE). For this embodiment, the heat exchanger 192 is configured to receive low-pressure compressor discharge bleed air to cool the air discharged from the HP compressor 116 before the cooled HP compressor air is delivered to cool the bearings 180 and optionally other components. The low-pressure compressor discharge bleed air may be discharged from the core air flow path 132 and directed to the heat exchanger 192 via a first delivery conduit 194. The bleed air from the HP compressor 116 may be directed to the heat exchanger 192 via a second delivery conduit 196. After being cooled by the station 2.5 bleed air at the heat exchanger 192, the cooled bleed air from the HP compressor 116 may be directed to the bearings 180 via a third delivery conduit 198. Although not shown, station 2.5 bleed air may be directed from heat exchanger 192 to any suitable location, such as to a core compartment, back to core air flow path 132, to another heat exchanger, to an underhood compartment (for FADEC system thermal management), to a turbine section (e.g., HP turbine 122, for turbine cooling), a compressor section (e.g., HP compressor 116, for compressor cooling), or to another suitable location.

[0035] It should be understood that Figure 1 The gas turbine engine 100 shown in the embodiment is provided as an example only, and in other example embodiments, the gas turbine engine 100 may have any other suitable configuration. Additionally or alternatively, aspects of the present disclosure may be used with other suitable aviation gas turbine engines (e.g., turboshaft engines, turboprop engines, turbojet engines, etc.).

[0036] Figure 2 A perspective view of a heat exchanger 200 according to an exemplary embodiment of the present disclosure is provided. The heat exchanger 200 may be implemented as, for example Figure 1 BAHE provided in. As shown, the heat exchanger 200 defines a vertical direction V, a lateral direction L, and a transverse direction T that are orthogonal to each other. The heat exchanger 200 includes a plurality of exchanger units 210. The exchanger units 210 can be compactly arranged in any suitable configuration. For this embodiment, the heat exchanger 200 includes twenty (20) exchanger units 210, including ten right exchanger units 211-220 stacked on top of each other along the vertical direction V and ten left exchanger units 221-230 stacked on top of each other along the vertical direction V. Although Figure 2 The heat exchanger 200 has twenty exchanger units 210, but in other example embodiments, the heat exchanger 200 may include any suitable number of exchanger units, such as one exchanger unit, eight exchanger units, fifty exchanger units, etc. In addition, in other embodiments, the exchanger units 210 may be placed side by side instead of stacked on each other.

[0037] Reference now Figure 2 , 3 and 4, Figure 3 Provided Figure 2 FIG. 2 is a perspective view of a first exchanger unit 211 of a heat exchanger 200 . Figure 4 Provided along Figure 3 4-4 of the cross-sectional view of the core of the first exchanger unit 211. Typically, each exchanger unit 210 of the heat exchanger 200 has a core and two manifolds. The core of each exchanger unit 210 defines a first channel and a second channel. The first channel can receive a first fluid, and the second channel can receive a second fluid. The core of one or more exchanger units 210 can be formed by a plurality of unit cells arranged in flow communication with each other. Alternatively, the core of one or more exchanger units 210 can be formed as an integral block.

[0038] For example, as shown, the first switch unit 211 includes a core 240 that defines a first channel 241 (in Figure 4 ) and a second channel 242 (outlined with a dotted line in Figure 4Outlined with solid lines in the figure). The first channel 241 can receive the first fluid F1 and the second channel 242 can receive the second fluid F2. The first fluid F1 and the second fluid F2 can both be, for example, air. In this regard, the heat exchanger 200 can be an air-to-air heat exchanger. The first fluid F1 flowing through the first channel 241 can be hotter and at a higher pressure than the second fluid F2 flowing through the second channel 242, and vice versa. In this way, as the first fluid F1 and the second fluid F2 flow through the first exchanger unit 211, thermal energy can be exchanged between the first fluid F1 and the second fluid F2. For this embodiment, the first fluid F1 (e.g., Figure 4 The outflow page represented by the "circle point" in FIG. 2 is relative to the second fluid F2 (such as Figure 4 In the countercurrent direction of the inflow page) represented by the "circle X" in the figure.

[0039] Although the core 240 of the first switch unit 211 is Figure 3 Although shown as a straight channel configuration, the core 240 of the first switch unit 210 (as well as the cores of the other switch units 210) may have other suitable configurations, such as a double U-bend channel configuration, a single U-bend configuration, etc.

[0040] The first exchanger unit 211 includes a first manifold 244 and a second manifold 246. Typically, the first manifold 244 distributes the second fluid F2 to the second channel 242 and receives the first fluid F1 from the first channel 241. The first manifold 244 can be arranged to keep the first fluid F1 and the second fluid F2 fluidly separated. Similarly, the second manifold 246 distributes the first fluid F1 to the first channel 241 and receives the second fluid F2 from the second channel 242. The second manifold 246 can be arranged to keep the first fluid F1 and the second fluid F2 fluidly separated. The first manifold 244 and / or the second manifold 246 can be connected to the manifold flow of the adjacent exchanger unit so that the first fluid F1 and / or the second fluid F2 can flow between the exchanger units 210 of the heat exchanger 200.

[0041] Each exchanger unit 210 of the heat exchanger 200 may be configured in the same or similar manner as the first exchanger unit 211 provided above. In this manner, each exchanger unit 210 of the heat exchanger 200 may have a core arranged in the same or similar manner as the core 240 of the first exchanger unit 211 and two manifolds arranged in the same or similar manner as the first manifold 244 and the second manifold 246 of the first exchanger unit 211. The core of each exchanger unit 210 defines a first channel and a second channel, just as the core 240 defines a first channel 241 and a second channel 242.

[0042] Reference now Figure 5 , provides a schematic diagram of a heat exchanger 300 according to an exemplary aspect of the present disclosure. The heat exchanger 300 can be similar to the one described above with reference to Figures 1 to 4 The exemplary heat exchanger(s) 192 are configured in a similar manner.

[0043] Figure 5 The exemplary heat exchanger 300 includes a first fluid path defining a first fluid inlet and a first fluid outlet and a second fluid path defining a second fluid inlet and a second fluid outlet. The first fluid path is a "hot" fluid path 302, and the second fluid path is a "cold" fluid path 304. In this manner, the first fluid inlet can be a hot fluid inlet 306, the first fluid outlet can be a hot fluid outlet 308, the second fluid inlet can be a cold fluid inlet 310, and the second fluid outlet can be a cold fluid outlet 312. As used herein, the hot fluid path 302 refers to a fluid path for a fluid that provides heat transfer to a fluid provided through the cold fluid path 304, while as used herein, the cold fluid path 304 refers to a fluid path for a fluid that receives heat transfer from a fluid through the hot fluid path 302.

[0044] During operation of the heat exchanger 300, particularly during operation of the heat exchanger 300 when the gas turbine engine 100 incorporating the heat exchanger 300 operates the high pressure spool at 100% capacity, the heat exchanger 300 defines: a temperature difference θ, in degrees Celsius (C), between the fluid provided through the hot fluid inlet 306 and the fluid provided through the cold fluid inlet 310; a temperature difference β, in degrees Celsius, between the fluid provided through the cold fluid outlet 312 and the fluid provided through the cold fluid inlet 310; a mass flow rate m of the fluid provided through the cold fluid inlet 310 in the heat exchanger 300; c , in kilograms per second (kg / s); the mass flow rate m of the fluid provided through the hot fluid inlet 306 in the heat exchanger 300 h , in kg / s; the specific heat capacity cp of the fluid provided through the cold fluid inlet 310 in the heat exchanger 300 c , in units of joules per kilogram Kelvin (J / kg-K); and the specific heat capacity cp of the fluid provided in the heat exchanger 300 through the hot fluid inlet 306 h , in J / kg-K. These parameters can be used to characterize the effectiveness of heat exchanger 300, as described elsewhere herein.

[0045] As previously mentioned, the inventors unexpectedly discovered during the engine design process that there is a relationship between the effectiveness of a heat exchanger and the ease with which airflow can be supplied to the heat exchanger. This relationship is represented by the air-to-air heat exchanger potential. The inventors have discovered that an air-to-air heat exchanger having an air-to-air heat exchanger potential within one of the ranges specified herein provides a heat exchanger that is both compact and effective in handling the heat load.

[0046] The air-to-air heat exchanger potential is a dimensionless quantity that is related to the effectiveness of the heat exchanger and the gas turbine engine's air flow conductivity. The effectiveness provides a measure of how effectively the heat exchanger can transfer heat between a first fluid (e.g., a cold fluid) and a second fluid (e.g., a hot fluid), and is a function of the temperature, mass flow rate, and heat capacity of the first and second fluids flowing through the heat exchanger. The air flow conductivity provides a measure of how easily air flows through the engine core into the heat exchanger, and is a function of the fan diameter of the gas turbine engine's fan, the engine length of the gas turbine engine, the bypass ratio of the gas turbine engine, and the overall pressure ratio of the gas turbine engine. As such, the air flow conductivity is based on the architecture of the gas turbine engine.

[0047] As engine designers continue to increase the bypass ratio of an engine, the ease of supplying airflow to a heat exchanger in flow communication with the engine core decreases exponentially, as does the air-to-air heat exchanger potential value. This suggests that a heat exchanger having a high effectiveness value may be useful in handling the heat load of a high bypass turbofan engine. In general, the combination of higher effectiveness and airflow conductivity results in a higher potential for the heat exchanger to handle more heat load. A heat exchanger in flow communication with a gas turbine engine having an air-to-air heat exchanger potential within the ranges specified herein may help achieve heat loads in a high bypass turbofan engine, while taking into account certain considerations.

[0048] In particular, the ranges of air-to-air heat exchanger potentials for air-to-air heat exchangers mentioned herein capture a specific subset of the architectures for air-to-air heat exchangers and gas turbines that take into account the various benefits and disadvantages of selecting one architectural architecture for the heat exchanger and / or gas turbine engine over another. In this regard, as discovered by the inventors, the ranges of air-to-air heat exchanger potentials for air-to-air heat exchangers provided herein strike a balance between the ease of supplying air flow to the heat exchanger, the compactness and weight of the heat exchanger, the ability of the heat exchanger to handle heat loads, the susceptibility of the heat exchanger passages to becoming plugged or contaminated, the manufacturability of the heat exchanger, the manufacturability of the gas turbine engine, the thrust output of the gas turbine engine, and the exhaust flow losses on the gas turbine engine. Therefore, a heat exchanger having an air-to-air heat exchanger potential within the ranges specified herein can ensure that the architecture of the heat exchanger and the architecture of the gas turbine engine are such that the heat exchanger is optimally compact and effective in handling heat loads.

[0049] In addition, using the air-to-air heat exchanger potential value, the inventors found that the number of suitable or feasible engine and / or heat exchanger designs that allow the heat exchanger to meet the compactness, weight and heat load requirements can be greatly reduced, thereby facilitating a faster down-selection of designs to be considered when developing a gas turbine engine with an air-to-air heat exchanger. These benefits provide a deeper understanding of the requirements of a given gas turbine engine before specific technical, integration and system requirements are fully developed. It may also prevent late redesign. For example, the selection of the effectiveness of a heat exchanger can be facilitated by using the air-to-air heat exchanger potential value, which can help determine the required channel diameter and wall thickness of the core of the heat exchanger, the location of the heat exchanger in the gas turbine engine, and the flow requirements of the hot and cold fluid flows. In addition, using the air-to-air heat exchanger potential can eliminate or otherwise reduce the implementation of heat exchangers that have too low effectiveness values ​​to enable them to achieve the heat load requirements required for the gas turbine engine. A lower effectiveness value may indicate that the size of the heat exchanger needs to be adjusted to increase the throughput of a given engine characteristic.

[0050] Reference now Figure 1 , 2 , 3, 4, 5 and 6, Figure 6 Various relationships between heat exchanger characteristics and the operating and architectural characteristics of the gas turbine engine are listed. It is noteworthy that the gas turbine engine 100 and the heat exchanger 200 in flow communication with the gas turbine engine 100 are arranged so that the heat exchanger 200 has an air-to-air heat exchanger potential AHEP. The air-to-air heat exchanger potential AHEP is related to the effectiveness ε of the heat exchanger 200 HXA dimensionless quantity related to the air flow conductance ACF of the gas turbine engine 100. As will be explained more fully below, the effectiveness ε HX is a function of the expected characteristics of the various flows (hot fluid flow and cold fluid flow) through heat exchanger 200 , and air flow conductance ACF is a function of the structural architecture of gas turbine engine 100 .

[0051] The air-to-air heat exchanger potential AHEP is defined as the product of one-half of the effectiveness ε associated with the air-to-air heat exchanger 200 HX multiplied by the air flow conductance ACF associated with the gas turbine engine 100. In this regard, the air-to-air heat exchanger potential AHEP is related to the effectiveness ε of the heat exchanger 200 HX is related to the air flow conductance ACF of the gas turbine engine 100. The inventors define the air-to-air heat exchanger potential AHEP as follows:

[0052] AHEP= (ε HX *ACF) 1 / 2 (1)

[0053] Validity HX Provides a measure of the degree to which the heat exchanger 200 exchanges heat between at least two flows. HX It is a dimensionless quantity (i.e. it has no unit of measurement).

[0054] The effectiveness of the heat exchanger 200 HX is a function of: the temperature difference θ between the fluid provided through the hot fluid inlet and the fluid provided through the cold fluid inlet, in degrees Celsius (C); the temperature difference β between the fluid provided through the cold fluid outlet and the fluid provided through the cold fluid inlet, in degrees Celsius; the mass flow rate m of the fluid provided through the cold fluid inlet in the heat exchanger 200 c , in kilograms per second (kg / s); the mass flow rate m of the fluid provided through the hot fluid inlet in the heat exchanger 200 h , in kg / s; the specific heat capacity cp of the fluid provided through the cold fluid inlet in the heat exchanger 200 c , in units of joules per kilogram Kelvin (J / kg-K); and the specific heat capacity cp of the fluid provided through the hot fluid inlet in the heat exchanger 200 h , in J / kg-K. In particular, the effectiveness ε of the heat exchanger 200 HX is equal to the mass flow rate m of the fluid supplied through the cold fluid inlet c (in kg / s), the specific heat capacity cp of the fluid supplied through the cold fluid inlet cThe product of the temperature difference β (in degrees Celsius) between the fluid supplied through the cold fluid outlet and the fluid supplied through the cold fluid inlet, divided by the product of the temperature difference θ (in degrees Celsius) between the fluid supplied through the hot fluid inlet and the fluid supplied through the cold fluid inlet and the minimum value, which is the mass flow rate m of the fluid supplied through the hot fluid inlet h (in kg / s) and the specific heat capacity cp of the fluid supplied through the hot fluid inlet h (in J / kg-K) or the mass flow rate m of the fluid provided through the cold fluid inlet c (in kg / s) and the specific heat capacity cp of the fluid supplied through the cold fluid inlet c (in J / kg-K). It is worth noting that each of these parameters refers to the value when the gas turbine engine 100 containing the heat exchanger 200 operates the high-voltage spool at 100% capacity or at maximum speed. In this way, the inventors define the effectiveness ε of a given heat exchanger as follows HX :

[0055]

[0056] The air flow conductance coefficient ACF associated with the gas turbine engine 100 provides a measure of the ease with which air flows through the gas turbine engine 100. The air flow conductance coefficient ACF is defined as the coefficient obtained by dividing the fan diameter D by FAN The fan diameter D is determined by dividing the fan diameter D by the product defined by the engine length L of the gas turbine engine 100 multiplied by the bypass ratio BPR of the gas turbine engine 100 multiplied by the overall pressure ratio OPR of the gas turbine engine 100. In other words, the fan diameter D FAN The product of the engine length L, the bypass ratio BPR and the total pressure ratio OPR of the engine is equal to the air flow conductance coefficient ACF. The air flow conductance coefficient ACF is a dimensionless quantity. The inventors define the air flow conductance coefficient ACF as follows:

[0057] ACF= D FAN / (L*BPR*OPR) (3)

[0058] Fan diameter D FAN The fan diameter D is defined as the distance between the leading edge tip of one fan blade 136 and the leading edge tip of the diametrically opposite fan blade 136. In other words, the fan diameter D FAN Defined as the fan radius R FAN Multiply by two, or D in mathematics FAN =R FAN *2, where the fan radius R FANSpanning from longitudinal centerline 102 to the leading edge tip of one of fan blades 136. Fan diameter D FAN The unit of measurement is meter (m). In some exemplary embodiments, the fan diameter D of the fan 134 of the gas turbine engine 100 is FAN In other exemplary embodiments, the fan diameter D of the fan 134 of the gas turbine engine 100 is between 0.5 m and 5 m. FAN In the case where the fan section 104 includes a plurality of fan stages, the fan diameter D FAN Will be determined based on the fan with the largest fan diameter.

[0059] As used herein, the engine length L refers to the length between the forward tip of the rotatable rotor 144 and the rear flange 143 of the gas turbine engine 100 along the axial direction A of the gas turbine engine 100. The rear flange 143 refers to a circumferential flange near the rear end of the gas turbine engine 100 for coupling the tail cone 141 to the rest of the gas turbine engine 100. The unit of measurement of the engine length L is meter (m). In certain exemplary embodiments, the engine length L is between 1m and 12m, for example, between 1.2m and 10m.

[0060] The bypass ratio BPR of the gas turbine engine 100 is defined by the ratio of the mass flow rate of the first portion of air 158 flowing through the bypass passage 152 to the mass flow rate of the second portion of air 160 entering the engine core 106 through the core inlet 110. In some example embodiments, the bypass ratio BPR of the gas turbine engine 100 may be between three and twenty (3-20). In other example embodiments, the bypass ratio BPR of the gas turbine engine 100 may be between three and ten (3-10). In further example embodiments, the bypass ratio BPR of the gas turbine engine 100 may be between ten and twenty (10-20).

[0061] The overall pressure ratio OPR refers to the pressure of the gas flow at the outlet of the compressor section of the turbine 106 of the gas turbine engine 100 (e.g., at a location immediately downstream of the most downstream stage of the compressor rotor blades of the HP compressor 116) and the pressure of the gas flow provided to the turbine 106 of the gas turbine engine 100 (e.g., at a location immediately downstream of the most downstream stage of the compressor rotor blades of the HP compressor 116). Figure 1 In some example embodiments, the total pressure ratio OPR is between 10 and 80.

[0062] In some embodiments, for a bypass ratio BPR between 3 and 10 and an effectiveness ε between 0.5 and 0.9 associated with gas turbine engine 100 HX, the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.028 and 0.067, and for a bypass ratio BPR between 10 and 20 associated with the gas turbine engine 100 and an effectiveness ε between 0.3 and 0.9 HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.015 and 0.038. Figure 7 The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0063] In yet other embodiments, for a bypass ratio BPR between 3 and 20 and an effectiveness ε between 0.5 and 0.9 associated with the gas turbine engine 100, HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.020 and 0.067. Figure 8 The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0064] In other embodiments, for a bypass ratio BPR between 3 and 10 and an effectiveness ε between 0.5 and 0.9 associated with the gas turbine engine 100 HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.028 and 0.067. Fig. 9 The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0065] In some further embodiments, for a bypass ratio BPR between 10 and 20 and an effectiveness ε between 0.3 and 0.9 associated with the gas turbine engine 100, HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.015 and 0.038. Fig.10 The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0066] In yet other embodiments, for a bypass ratio BPR between 10 and 20 and an effectiveness ε between 0.3 and 0.5 associated with a gas turbine engine, HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.015 and 0.028. Fig.11The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0067] In a further embodiment, for a bypass ratio BPR between 10 and 20 and an effectiveness ε between 0.5 and 0.9 associated with a gas turbine engine HX , the air-to-air heat exchanger 200 has an air-to-air heat exchanger potential AHEP between 0.020 and 0.038. Fig.12 The air-to-air heat exchanger potential AHEP of this example embodiment is graphically depicted as a function of the bypass ratio BPR.

[0068] Reference now Fig.13 , various examples of gas turbine engines each having an air-to-air heat exchanger in flow communication therewith are provided below.

[0069] Example 1: In a first example, a gas turbine engine comprises an air-to-air heat exchanger. The air-to-air heat exchanger is arranged such that the effectiveness ε HX The gas turbine engine has a fan diameter D of 0.5 m. FAN The gas turbine engine defines a bypass ratio BPR of 3.0, an engine length of 1.2 m and an overall pressure ratio of 10. For this first example, the air-to-air heat exchanger potential AHEP is 0.065.

[0070] Example 2: In a second example, the gas turbine engine comprises an air-to-air heat exchanger. The air-to-air heat exchanger is arranged such that the effectiveness ε HX The gas turbine engine has a fan diameter D of 3 m. FAN The gas turbine engine defines a bypass ratio BPR of 10, an engine length of 4 m and an overall pressure ratio of 50. For this second example, the air-to-air heat exchanger potential AHEP is 0.032.

[0071] Example 3: In a third example, the gas turbine engine comprises an air-to-air heat exchanger. The air-to-air heat exchanger is arranged such that the effectiveness ε HX The gas turbine engine has a fan diameter D of 5 m. FAN The gas turbine engine defines a bypass ratio BPR of 20, an engine length of 10 m and an overall pressure ratio of 80. For this third example, the air-to-air heat exchanger potential AHEP is 0.017.

[0072] Fig.14 A flow chart of a method 400 of operating a gas turbine engine having a heat exchanger in flow communication therewith is provided.

[0073] At 402, the method includes operating a gas turbine engine having a fan and an engine core positioned downstream of the fan, the engine core having a compressor section including one or more compressors, the engine core defining a core air flow path, the gas turbine engine having an air-to-air heat exchanger in flow communication with the core air flow path and having an air-to-air heat exchanger potential defined by one-half of a product of an effectiveness associated with the air-to-air heat exchanger multiplied by an air flow conductance coefficient related to a fan diameter of the fan, a bypass ratio of the gas turbine engine, and a number of compressor stages of the gas turbine engine, and wherein the gas turbine engine is operated such that for a bypass ratio between 3 and 10 and an effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.028 and 0.067, and for a bypass ratio between 10 and 20 and an effectiveness between 0.3 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.015 and 0.038.

[0074] In some embodiments, the air-to-air heat exchanger includes one or more exchanger units, each exchanger unit having a core defining a plurality of channels. Figure 2 As shown, the air-to-air heat exchanger may include twenty exchanger units.

[0075] In some embodiments, the gas flow conductance coefficient associated with the gas turbine engine is defined as a quotient determined by dividing the fan diameter of the fan of the gas turbine engine by the product, which is defined by the engine length of the gas turbine engine multiplied by the bypass ratio of the gas turbine engine multiplied by the total pressure ratio of the gas turbine engine. In this way, the gas flow conductance coefficient is a function of the fan diameter of the fan of the gas turbine engine, the engine length, the bypass ratio of the gas turbine engine, and the total pressure ratio. In some further embodiments, the diameter of the fan of the gas turbine engine is between 0.5m and 5m. In other embodiments, the diameter of the fan of the gas turbine engine is between 1.8m and 5m. In some other embodiments, the total pressure ratio is between 10 and 80.

[0076] In some embodiments, the gas turbine engine is operated such that the air-to-air heat exchanger potential is between 0.020 and 0.067 for a bypass ratio between 3 and 20 and an efficiency between 0.5 and 0.9 associated with the gas turbine engine. The air-to-air heat exchanger potential according to such embodiments is between 0.020 and 0.067. Figure 8 Represented graphically in .

[0077] In some embodiments, the gas turbine engine is operated such that the air-to-air heat exchanger potential is between 0.028 and 0.067 for a bypass ratio between 3 and 10 and an efficiency between 0.5 and 0.9 associated with the gas turbine engine. The air-to-air heat exchanger potential according to such embodiments is between 0.028 and 0.067. Fig. 9 Represented graphically in .

[0078] In some embodiments, the gas turbine engine is operated such that the air-to-air heat exchanger potential is between 0.015 and 0.038 for a bypass ratio between 10 and 20 and an efficiency between 0.3 and 0.9 associated with the gas turbine engine. The air-to-air heat exchanger potential according to such embodiments is between 0.015 and 0.038. Fig.10 Represented graphically in .

[0079] In some embodiments, the gas turbine engine is operated such that the air-to-air heat exchanger potential is between 0.015 and 0.028 for a bypass ratio between 10 and 20 and an efficiency between 0.3 and 0.5 associated with the gas turbine engine. The air-to-air heat exchanger potential according to such embodiments is between 0.015 and 0.028. Fig.11 Represented graphically in .

[0080] In some embodiments, the gas turbine engine is operated such that the air-to-air heat exchanger potential is between 0.020 and 0.038 for a bypass ratio between 10 and 20 and an efficiency between 0.5 and 0.9 associated with the gas turbine engine. The air-to-air heat exchanger potential according to such embodiments is between 0.020 and 0.038. Fig.12 Represented graphically in .

[0081] Although specific features of various embodiments may be shown in some drawings and not in other drawings, this is for convenience only. According to the principles of the present disclosure, any feature of a drawing may be referenced and / or claimed in combination with any feature of any other drawing.

[0082] This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the present disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the present disclosure is defined by the claims, and may include other examples that occur to one skilled in the art. Such other examples are intended to fall within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that do not differ substantially from the literal language of the claims.

[0083] Further aspects are provided by the subject matter of the following clauses:

[0084] A gas turbine engine comprising: a compressor section, a combustion section, and a turbine section in a series flow arrangement; and an air-to-air heat exchanger having an air-to-air heat exchanger potential, the air-to-air heat exchanger potential being defined by the product raised to the power of two, the product being an effectiveness associated with the air-to-air heat exchanger multiplied by an airflow conductance associated with the gas turbine engine, and wherein for a bypass ratio associated with the gas turbine engine between 3 and 10 and the effectiveness between 0.5 and 0.9, the air-to-air heat exchanger potential is between 0.028 and 0.067, and for a bypass ratio associated with the gas turbine engine between 10 and 20 and the effectiveness between 0.3 and 0.9, the air-to-air heat exchanger potential is between 0.015 and 0.038.

[0085] The gas turbine engine according to the preceding clause, wherein the air-to-air heat exchanger further comprises one or more exchanger units, each exchanger unit having a core defining a plurality of channels.

[0086] A gas turbine engine according to one or more of the preceding clauses, wherein the air-to-air heat exchanger defines a cold fluid inlet, a cold fluid outlet, a hot fluid inlet and a hot fluid outlet, and wherein the effectiveness is equal to a first product divided by a second product, wherein the first product is the mass flow rate m of the fluid provided through the cold fluid inlet c The second product is the product of a temperature difference θ (in degrees Celsius) between the fluid provided through the hot fluid inlet and the fluid provided through the cold fluid inlet and a minimum value, wherein the minimum value is the mass flow rate m of the fluid provided through the hot fluid inlet. h (in kg / s) and the specific heat capacity cp of the fluid provided through the hot fluid inlet h (in J / kg-K) or the mass flow rate m of the fluid provided through the cold fluid inlet c (in kg / s) and the specific heat capacity cp of the fluid provided through the cold fluid inlet c (unit: J / kg-K)

[0087] The gas turbine engine according to one or more of the preceding clauses, further comprising: a fan, and wherein the airflow conductance coefficient associated with the gas turbine engine is defined as a quotient determined by dividing a fan diameter of the fan of the gas turbine engine by a product defined by an engine length of the gas turbine engine multiplied by a bypass ratio of the gas turbine engine multiplied by an overall pressure ratio of the gas turbine engine.

[0088] Gas turbine engine according to one or more of the preceding clauses, wherein the fan diameter is between 0.5 m and 5 m.

[0089] Gas turbine engine according to one or more of the preceding clauses, wherein the fan diameter is between 1.8 m and 3.5 m.

[0090] A gas turbine engine according to one or more of the preceding clauses, wherein said overall pressure ratio is between 10 and 80.

[0091] The gas turbine engine according to one or more of the preceding clauses, wherein the overall pressure ratio is defined when the gas turbine engine is operating a high pressure spool of the gas turbine engine at 100% capacity.

[0092] The gas turbine engine according to one or more of the preceding clauses, wherein for a bypass ratio between 3 and 20 and the effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.020 and 0.067.

[0093] The gas turbine engine according to one or more of the preceding clauses, wherein for a bypass ratio between 3 and 10 and the effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.028 and 0.067.

[0094] The gas turbine engine according to one or more of the preceding clauses, wherein for a bypass ratio between 10 and 20 and the effectiveness between 0.3 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.015 and 0.038.

[0095] The gas turbine engine according to one or more of the preceding clauses, wherein for a bypass ratio between 10 and 20 and the effectiveness between 0.3 and 0.5 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.015 and 0.028.

[0096] The gas turbine engine according to one or more of the preceding clauses, wherein for a bypass ratio between 10 and 20 and the effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.020 and 0.038.

[0097] The gas turbine engine according to one or more of the preceding clauses, wherein the overall pressure ratio is defined when the gas turbine engine is operating a high pressure spool of the gas turbine engine at 100% capacity.

[0098] An air-to-air heat exchanger in flow communication with a core air flow path of a gas turbine engine, the air-to-air heat exchanger having an air-to-air heat exchanger potential defined by the product raised to the power of two, the product being an effectiveness associated with the air-to-air heat exchanger multiplied by an air flow conductance coefficient related to a fan diameter of a fan of the gas turbine engine, an engine length of the gas turbine engine, a bypass ratio of the gas turbine engine, and an overall pressure ratio of the gas turbine engine, the compressor section having one or more compressors and the fan section having a fan, and wherein for a bypass ratio associated with the gas turbine engine between 3 and 10 and the effectiveness between 0.5 and 0.9, the air-to-air heat exchanger potential is between 0.028 and 0.067, and for a bypass ratio associated with the gas turbine engine between 10 and 20 and the effectiveness between 0.3 and 0.9, the air-to-air heat exchanger potential is between 0.015 and 0.038.

[0099] An air-to-air heat exchanger according to one or more of the preceding clauses, wherein the airflow conductance associated with the gas turbine engine is defined as a quotient determined by dividing the fan diameter of the fan by a product defined by the engine length of the gas turbine engine multiplied by the bypass ratio of the gas turbine engine multiplied by the total pressure ratio of the gas turbine engine.

[0100] An air to air heat exchanger according to one or more of the preceding clauses, wherein the fan diameter is between 0.5 m and 5 m.

[0101] An air-to-air heat exchanger according to one or more of the preceding clauses, wherein the overall pressure ratio is between 10 and 80.

[0102] An air to air heat exchanger according to one or more of the preceding clauses, wherein the overall pressure ratio is defined when the gas turbine engine is operating a high pressure spool of the gas turbine engine at 100% capacity.

[0103] A method includes operating a gas turbine engine having a fan and an engine core positioned downstream of the fan, the engine core having a compressor section including one or more compressors, the engine core defining a core air flow path, the gas turbine engine having an air-to-air heat exchanger in flow communication with the core air flow path and having an air-to-air heat exchanger potential defined by one-half the product of an effectiveness associated with the air-to-air heat exchanger multiplied by an air flow conductance, the air flow The conductance coefficient is related to the fan diameter of the fan, the bypass ratio of the gas turbine engine and the number of compressor stages of the gas turbine engine, and wherein the gas turbine engine is operated so that for a bypass ratio between 3 and 10 and the effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.028 and 0.067, and for a bypass ratio between 10 and 20 and the effectiveness between 0.3 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.015 and 0.038.

Claims

1. A gas turbine engine, characterized in that: include: a compressor section, a combustion section, and a turbine section in a series flow arrangement; and an air-to-air heat exchanger having an air-to-air heat exchanger potential defined by one-half the product of an effectiveness associated with the air-to-air heat exchanger multiplied by an air flow conductance associated with the gas turbine engine, and wherein for a bypass ratio between 3 and 10 and an effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.028 and 0.067, and for a bypass ratio between 10 and 20 and an effectiveness between 0.3 and 0.9 associated with the gas turbine engine, the air-to-air heat exchanger potential is between 0.015 and 0.

038.

2. The gas turbine engine according to claim 1, characterized in that The air-to-air heat exchanger further comprises one or more exchanger units, each exchanger unit having a core defining a plurality of channels.

3. The gas turbine engine according to claim 2, characterized in that wherein the air-to-air heat exchanger defines a cold fluid inlet, a cold fluid outlet, a hot fluid inlet, and a hot fluid outlet, and wherein the effectiveness is equal to a first product divided by a second product, wherein the first product is a mass flow rate m of a fluid provided through the cold fluid inlet c The second product is the product of a temperature difference θ (in degrees Celsius) between the fluid provided through the hot fluid inlet and the fluid provided through the cold fluid inlet and a minimum value, wherein the minimum value is the mass flow rate m of the fluid provided through the hot fluid inlet. h (in kg / s) and the specific heat capacity cp of the fluid provided through the hot fluid inlet h (in J / kg-K) or the mass flow rate m of the fluid provided through the cold fluid inlet c (in kg / s) and the specific heat capacity cp of the fluid provided through the cold fluid inlet c (unit: J / kg-K) 4. The gas turbine engine according to claim 1, characterized in that Further including: Fan, and wherein the air flow conductance associated with the gas turbine engine is defined as a quotient determined by dividing a fan diameter of the fan of the gas turbine engine by a product defined by an engine length of the gas turbine engine multiplied by a bypass ratio of the gas turbine engine multiplied by an overall pressure ratio of the gas turbine engine.

5. The gas turbine engine according to claim 4, characterized in that The fan diameter is between 0.5m and 5m.

6. The gas turbine engine according to claim 4, characterized in that The fan diameter is between 1.8m and 3.5m.

7. The gas turbine engine according to claim 4, characterized in that The total pressure ratio is between 10 and 80.

8. The gas turbine engine according to claim 4, characterized in that Wherein the overall pressure ratio is defined when the gas turbine engine is operating a high pressure spool of the gas turbine engine at 100% capacity.

9. The gas turbine engine according to claim 1, characterized in that Wherein for a bypass ratio of between 3 and 20 and the effectiveness of between 0.5 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.020 and 0.

067.

10. The gas turbine engine according to claim 1, characterized in that Wherein for a bypass ratio between 3 and 10 and the effectiveness between 0.5 and 0.9 associated with the gas turbine engine, the air to air heat exchanger potential is between 0.028 and 0.067.

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