Steam heated flange for thermal gradient control

A turbine engine assembly includes a first case structure with a first flange and a second case structure that includes a second flange. The second flange is configured for securement to the first flange at a connection interface. At least one steam conduit is in thermal communication with the connection interface and configured to receive a portion of a flow of steam to heat the connection interface. Heating the connection interface provides for control of a thermal gradient generated by a difference in temperature in temperatures on either side of the connection interface.

TECHNICAL FIELD

The present disclosure relates generally to an aircraft propulsion system that includes a steam generation system and utilizes steam to reduce thermal gradients at bolted flanged connections between case structures.

BACKGROUND

Reduction and/or elimination of carbon emissions generated by aircraft operation is a stated goal of aircraft manufacturers and airline operators. Steam generation and injection into the core flow can improve propulsive efficiencies. Higher operating temperatures and pressures also improve engine efficiencies. Such increases in temperatures and pressures can increases stresses on bolted flanged connections between case structures. Thermal gradients across the bolted flanged connections are generated by the extreme temperature differences between high temperature exhaust gases within the case structure and low temperature ambient conditions at the outer surface of the case structure. Increased temperatures may further challenge such bolted flanged connections and present challenges to connection performance and durability.

SUMMARY

A turbine engine assembly according to one example disclosed embodiment includes, among other possible things, a compressor section where an inlet airflow is compressed, a combustor section where the compressed inlet airflow is mixed with fuel and ignited to generate an exhaust gas flow that is communicated through a core flow path, a turbine section through which the exhaust gas flow expands to generate a mechanical power output, an evaporator system that generates a flow of steam, a first case structure that includes a first flange, a second case structure that includes a second flange, the second flange is configured for securement to the first flange at a connection interface, and at least one steam conduit that is in thermal communication with the connection interface and configured to receive a portion of the flow of steam to heat the connection interface.

In a further embodiment of the foregoing turbine engine assembly, the at least one steam conduit includes a first steam conduit that is in thermal communication with the first flange and a second steam conduit that is in thermal communication with the second flange.

In a further embodiment of any of the foregoing turbine engine assemblies, the at least one steam conduit is an integral portion of at least one of the first flange and the second flange.

In a further embodiment of any of the foregoing turbine engine assemblies, each of the first flange and the second flange includes an outer peripheral surface and the at least one steam conduit is supported on the outer peripheral surface.

In a further embodiment of any of the foregoing turbine engine assemblies, the first case structure and the second case structure circumscribe portions of the combustor section and the turbine section.

In a further embodiment of any of the foregoing, the turbine engine assembly includes a first valve that controls the portion of the flow of steam that is communicated to the at least one steam conduit.

In a further embodiment of any of the foregoing, the turbine engine assembly includes a controller that is programmed to operate the first valve to control a temperature of the connection interface.

In a further embodiment of any of the foregoing, the turbine engine assembly includes at least one sensor that provides information indicative of relative temperatures between an inner surface of each of the first case structure and second the second case structure.

In a further embodiment of any of the foregoing turbine engine assemblies, the steam system includes an evaporator where thermal energy from the exhaust gas flow is utilized to generate the flow of steam and at least a portion of the flow of steam is injected into the core flow path.

In a further embodiment of any of the foregoing turbine engine assemblies, the at least one steam conduit includes an outlet for the portion of the flow of steam that is in communication with an injection location for injecting exhausted steam into the core flow path.

In a further embodiment of any of the foregoing, the turbine engine assembly includes a condenser where water is extracted from the exhaust gas flow and the evaporator is configured to receive a flow of water from the condenser.

In a further embodiment of any of the foregoing, the turbine engine assembly further includes a fuel system that is configured to provide a non-carbon-based fuel to the combustor section.

In a further embodiment of any of the foregoing, the turbine engine assembly further includes an intercooling system where a flow of water is utilized for cooling a portion of the compressed inlet flow.

An aircraft propulsion system according to another example disclosed embodiment includes, among other possible things, a core engine section that defines a core flow path where an inlet airflow is compressed, mixed with fuel and ignited to generate an exhaust gas flow that is communicated through a core flow path, a condenser where water is extracted from the exhaust gas flow, an evaporator system where thermal energy from the exhaust gas flow is utilized to generate a steam flow for injection into the core flow path, a first case structure that includes a first flange, a second case structure that includes a second flange, the second flange configured for securement to the first flange at a connection interface, and at least one steam conduit that is in thermal communication with the connection interface and configured to receive a steam flow from the evaporator system to heat the connection interface. A control valve is configured to control the flow of steam into the at least one steam conduit. A controller is programmed to operate the control valve to maintain a temperature differential of the connection interface within a defined range by adjusting a flow of steam through the at least one steam conduit.

In a further embodiment of the foregoing aircraft propulsion system, the at least one steam conduit includes a first steam conduit that is in thermal communication with a first outer peripheral surface of the first flange and a second steam conduit that is in thermal communication with the second flange.

In a further embodiment of any of the foregoing aircraft propulsion systems, the at least one steam conduit is an integral portion of at least one of the first flange and the second flange.

In a further embodiment of any of the foregoing aircraft propulsion systems, the first case structure and the second case structure circumscribe portions of the combustor section and the turbine section.

A method of operating a gas turbine engine, the method, according to another example disclosed embodiment includes, among other possible things, generating an exhaust gas flow that is communicated through a core flow path, expanding the gas flow through a turbine section to generate a mechanical power output, extracting water from the exhaust gas flow in a condenser, generating a steam flow by vaporizing the heating flow of water with heat from the exhaust gas flow in the evaporator system, and controlling a temperature of a connection interface between a first flange of a first case and a second flange of a second case by adjusting a flow of steam through at least one steam conduit that is in thermal communication with the connection interface.

In a further embodiment of the foregoing, the method further includes controlling the temperature of the connection interface to maintain a temperature differential between connection interface and an inner surface of the case structure that is exposed to the exhaust gas flow.

In a further embodiment of any of the foregoing, the method further includes exhausting the steam flow from the at least one steam conduit into the core flow path.

Although the different examples have the specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples.

DETAILED DESCRIPTION

FIG.1schematically illustrates an example propulsion system20that includes a steam heated flanged connection interface58for controlling a thermal gradient generated by the difference in temperature between hot exhaust gases and a relatively cool ambient environment. The disclosed example system reduces and controls the thermal gradient to reduce thermal stresses on the connection interface58.

The example propulsion system20includes a fan section24and a core engine section22. The core engine section22includes a compressor section26, a combustor section28and the turbine section30disposed along an engine longitudinal axis A. The fan section24drives inlet airflow along a bypass flow path B, while the compressor section26draws air in along a core flow path C. The inlet airflow is compressed and communicated to the combustor section28where the compressed core airflow is mixed with a fuel flow35and ignited to generate the exhaust gas flow82. The exhaust gas flow82expands through the turbine section30where energy is extracted to generate a mechanical power output utilized to drive the fan section24and the compressor section26.

Although an example engine architecture is disclosed by way of example, other turbine engine architectures are within the contemplation and scope of this disclosure. Moreover, although the disclosed non-limiting embodiment depicts a turbofan turbine engine, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines. Moreover, although the example engine20illustrates the engine components and sections disposed along a single common engine axis A, the engine sections and components may be arranged along multiple axes and have different relative orientations. Such alternate engine architectures are within the scope and contemplation of this disclosure. Additionally, the features of this disclosure may be applied to other engine configurations utilized to generate shaft power.

A fuel system32including at least a fuel tank34and a fuel pump36provides the fuel flow35to the combustor28. The example fuel system32is configured to provide a hydrogen-based fuel such as a liquid hydrogen (LH2). Although hydrogen is disclosed by way of example, other non-carbon-based fuels could be utilized and are within the contemplation of this disclosure. Moreover, the disclosed features may also be beneficial in an engine configured to operate with traditional carbon fuels and/or biofuels, such as sustainable aviation fuel.

An evaporator system38and condenser40are disposed downstream of the turbine section30and receive the exhaust gas flow82. The evaporator system38utilizes thermal energy from the exhaust gas flow82to generate a steam flow52from a water flow44extracted by the condenser40and separated from the gas flow in a water separator50. The condenser40cools the exhaust gas flow82to extract water that is separated from the gas in the water separator50and gathered in a tank42. A pump45pressurizes water for communication from the water tank42. In one disclosed example embodiment, a portion of the fuel flow35is utilized as a heat sink to cool the exhaust gas flow82in the condenser40. In another example embodiment, a cooling ram air flow88is used as the cold sink. Other cold sink flows may be utilized to cool the exhaust gas flow82within the condenser44and are within the contemplation and scope of this disclosure.

Water recovered with the condenser40may also be provided as an intercooling water flow46to the compressor section26. The water flow46is injected into a location48within the compressor section26to cool the core flow and thereby increase mass flow. The increased mass flow improves compressor operating efficiencies. The example intercooling water flow48is shown schematically and may be injected at any location within the compressor section26or upstream of the combustor28.

The steam flow52from the evaporator38is injected into the core flow path C at or upstream of the combustor28and increases mass flow through the turbine section30. The propulsion system20has an increased power output from the injected steam52due to an increasing mass flow through the turbine section30without a corresponding increase in work from the compressor section26. Although the steam flow52is shown as being injected into the combustor28, the steam flow48may be injected at other locations along the core flow path C and remain within the contemplation and scope of this disclosure.

Bolted flanges that connect case structures encounter large thermal gradients due to the high temperatures within the case structures and the relatively low temperatures at outer surfaces. The large thermal gradients generate a significant amount of stresses due to the differences in thermal expansions on inner and outer surfaces. Differences in thermal expansion can create prying due to circumferential thermal differences that become focused as stresses at the bolted flanged connection. The example propulsion system20utilizes a portion of the steam flow to reduce thermal differences by heating portions of the connection interface58. Raising the temperature of the connection interface58reduces the difference in temperature and thereby the thermal gradient.

The example system routes a portion54of the steam flow into thermal contact with the connection interface58. A control valve60is operated by a controller62to control a flow of the steam54to the connection interface58and maintain temperatures within a predefined range determined to limit a magnitude of the temperature gradient. The controller62receives information90indicative of a temperature and utilizes that information to control steam flow to the connection interface58. Exhaust steam flow56is communicated to the combustor28for introduction into the core flow.

Referring toFIG.2with continued reference toFIG.1, the connection interface58is schematically shown between a first flange66of a first case structure64and a second flange70of a second case structure68. A bolt72and nut74secure the first flange66to the second flange70. The bolt72and nut74may be of any configuration utilized to secure case structures together. As should be appreciated, the case structures64,68are full round structures disposed about the engine longitudinal axis A. Moreover, the flanges66,70include a plurality of openings for a corresponding number of bolts72and nuts74that are disposed about a circumference of the case structures64,68.

In one disclosed example embodiment the first case structure64and the second case structure68circumscribe portions of the combustor section28and the turbine section30. The first case structure64may be a diffuser case disposed at least partially around the combustor section28and the second case structure66may be a turbine case that is disposed at least partially around a portion of the turbine section30. Although specific case structures are disclosed by way of example, the example connection interface58may be utilized at any flanged connection between case structures of a core engine22.

An inner surface80of the case structures64,68is exposed to the hot exhaust gas flow82. The inner surface80of the case structures64,68is therefore of a temperature T2that is much higher than a temperature T1at an outer periphery84,86of each of the flanges66,70and an outer surface85of the case structures64,68. The temperature between T1and T2progressively cools in a direction toward the outer peripheries84,86.

A first steam conduit76and a second steam conduit78are provided about the outer peripheries of the first and second flanges66,70. Steam flow54through the conduits76,78is in thermal communication with the coolest parts of the connection interface58and thereby heats the connection interface58. Heating of the outer peripheral surfaces84,86reduces the temperature difference TDto provide a reduction in thermal expansion differences that in turn reduces stress. The steam flow54through the connection interface58is exhausted as a cooled steam flow56that is communicated to the combustor section28.

The first and second steam conduits76,78may be separate from the flanges66,70and are attached to provide the desired thermal communication of heat energy. Although first and second steam conduits76,78are disclosed by way of example, a single steam conduit that is in thermal contact with the outer peripheries of each of the flanges66,70may also be utilized and is within the contemplation and scope of this disclosure. Moreover, additional conduits may also be utilized and are within the scope and contemplation of this disclosure.

Moreover, although the example steam conduits76,78are shown as circular in cross-section, other conduit shapes that provide for the transfer of heat energy may also be utilized and are within the contemplation of this disclosure. For example, the cross-sectional shape of the conduits76,78could be oval, rectangular, square or an irregular shape. The example steam conduits76,78are formed from a material determined to transfer thermal energy into the flanges66,70. Moreover, additional structures and materials may be included to encourage and direct thermal energy into the flanges66,70.

The control valve60is operated to adjust the steam flow54into the conduits76,78to control the temperature T1. The controller62adjusts the control valve60based on information obtained indicative of the temperature differential TD. The controller62may obtain information that is utilized to estimate the temperatures based on specific operating conditions. The controller62may also obtain information from sensors92and94disposed at locations within the case structures64,68and the flanges66,70. The sensors92,94may directly measure temperatures at the specific locations or provide information that is utilized to determine or estimate temperatures.

The controller62is disclosed by way of example as programmed to operate the control valve60to adjust heating of the flanges66,70, the controller62may be programmed to operate other components to control steam flow54and thereby the amount of heat applied to each of the flanges66,70. Although a single control valve60is shown by way of example, additional control valves could be utilized to control steam flow individually and separately through each of the conduits76,78.

Moreover, the controller62is disclosed by way of example as adjusting operation of the valve60based on information from the sensors92,94. However, the controller62may also utilize information indicative of engine operation, including for example, shaft speeds, pressures and temperatures at other locations in the propulsion system20and information indicative of ambient conditions.

The example contoller62is a device and system for performing necessary computing or calculation operations and may be specially constructed for this purpose. Alternatively, the controller62may comprise at least a general-purpose computer selectively activated or reconfigured by a computer program stored in the computer. The controller62may further be a dedicated controller, or may be a program stored on an engine or aircraft controller.

The controller62may include a computer program directing operation. Such a computer program and also data required for its execution may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMS), EPROMs, EEPROMs, magnetic or optical cards, application specific integrated circuits (ASICs), or any type of media suitable for storing electronic instructions, and each coupled to a computer system bus. Furthermore, the computer referred to nay include a single processor or may be architectures employing multiple processor designs for increased computing capability.

Referring toFIG.3with continued reference toFIG.2, a partial axial view of the example connection interface58is shown with the steam conduits76,78disposed on the outer peripheral surfaces84,86of each of the flanges66,70. In this example embodiment, the conduits76,78are arranged to provide a circumferentially directed flow. The steam flow54cools as it heats the flanges66,70and is exhausted through an outlet98as a cooled steam flow56. Although a single inlet96and a single outlet98are shown and disclosed by example, additional inlets and outlets could be provided about the circumference of the connection interface to provide a flow of uniform temperature.

Referring toFIG.4, another example connection interface100is schematically shown and includes a first case102with a first flange104and a second case106with a second flange108. A first conduit110is integrated within the first flange104and a second conduit112is integrated within the second flange108. The integrated conduits110,112provide an alternate means of heating that may simplify constructions. Steam flow54is communicated to the integral conduits110,112to provide for the control of the temperature differential TDand thereby a reduction in the amount of stress generated. The controller62adjusts the control valve60to provides the steam flow54based on temperature information90.

The conduits110and112are shown as circular in cross-section, but may be of any shape. Moreover, although one conduit110,112is shown in each flange104,108, other numbers of conduits could be utilized and remain within the contemplation and scope of this disclosure.

Accordingly, example disclosed systems use thermal energy from steam generated for injection into the core flow to reduce and control the thermal gradient within a bolted flange connection interface to improve performance and durability.