Patent Description:
Reduction and/or elimination of carbon emissions generated by aircraft operation is a stated goal of aircraft manufacturers and airline operators. Gas turbine engines compress incoming core airflow, mix the compressed airflow with fuel that is ignited in a combustor to generate a high energy exhaust gas flow. Some energy in the high energy exhaust flow is recovered as it is expanded through a turbine section. Even with the use of alternate fuels, a large amount of energy in the form of heat is simply exhausted from the turbine section to atmosphere. The lost heat reduces the overall efficiency of the engine
Turbine engine manufacturers continue to seek further improvements to engine performance including improvements to reduce environmental impact while improving propulsive efficiencies.

<CIT> discloses a prior art exhaust gas treatment device and aircraft propulsion system.

<CIT> discloses a prior art method for reducing contrails during aircraft operation.

<CIT> discloses a prior art device to suppress contrail formation.

<CIT> discloses a prior art aircraft propulsion system.

According to an aspect of the present invention, there is provided a propulsion system for an aircraft as claimed in claim <NUM>.

Optionally, and in accordance with any of the above, the condenser is configured to receive a cooling flow to cool the high energy gas flow.

Optionally, and in accordance with any of the above, the plurality of spiral passages are defined between a plurality of curved layers that extend axially and curve about a condenser axis.

Optionally, and in accordance with any of the above, the plurality of curved layers include openings that are configured to exhaust water that is collected from the high energy gas flow to the collector.

Optionally, and in accordance with any of the above, the plurality of spiral passages include a hydrophilic coating.

Optionally, and in accordance with any of the above, the plurality of spiral passages include a hydrophobic coating.

Optionally, and in accordance with any of the above, the plurality of spiral passages include a textured surface.

Optionally, and in accordance with any of the above, the propulsion system includes a water storage tank and the collector that is configured to communicate water that is extracted from the high energy gas flow to the water storage tank via the water passage.

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 an example hydrogen steam injected intercooled turbine engine that is generally indicated at <NUM>. The engine <NUM> includes core engine with a core airflow path C through a fan <NUM>, a compressor section <NUM>, a combustor <NUM> and a turbine section <NUM>. The fan <NUM> drives inlet air as a core flow <NUM> into the compressor section <NUM>. In the compressor section <NUM>, the core flow <NUM> is compressed and communicated to a combustor <NUM>. In the combustor <NUM>, the core flow <NUM> is mixed with a hydrogen (H<NUM>) fuel flow <NUM> and ignited to generate a high energy gas flow <NUM> that expands through the turbine section <NUM> where energy is extracted and utilized to drive the fan <NUM> and the compressor section <NUM>. A bypass flow <NUM> may flow through the fan <NUM>, bypass the remaining components of the engine <NUM>, and exit through a fan nozzle <NUM>. The high energy gas flow <NUM> is exhausted from the turbine section <NUM> and communicated to a steam generation system <NUM> and a water recovery system <NUM> before being exhausted through a core nozzle <NUM>.

The engine <NUM> is configured to burn hydrogen provide by a fuel system <NUM>. The fuel system <NUM> includes a liquid hydrogen (LH<NUM>) tank <NUM> in communication with at least one pump <NUM>. The pump <NUM> drives a fuel flow <NUM> to the combustor <NUM>. LH<NUM> provides a thermal heat sink that can be utilized to cool various heat loads within the aircraft indicated at <NUM> and in the engine as indicated at <NUM>. The heat loads may include, for example and without limitation, super conducting electrics, a working fluid of an environmental control system of the aircraft, an air conditioning heat exchanger, and engine working fluid heat exchangers. Heat accepted into the hydrogen fuel flow increase the overall fuel temperature prior to injection into the combustor <NUM>.

A hydrogen expansion turbine <NUM> may be provided to reduce the pressure of the LH<NUM> fuel flow through expansion prior to communication to the combustor <NUM>. Expansion in the expansion turbine <NUM> provides for the temperatures and pressures of the fuel flow to enter the combustor <NUM> as a gas and not a liquid.

The steam injection system <NUM> uses the exhaust heat to generate a steam flow <NUM> by evaporating high pressure water through an evaporator <NUM>. The generated steam <NUM> may then be injected into compressed core airflow at a location <NUM> for communication into the combustor <NUM> to improve performance by increasing turbine mass flow and power output without additional work required by the compressor section. In one example embodiment the location <NUM> is upstream of the combustor <NUM>. Steam flow from the evaporator <NUM> may drive a steam turbine <NUM> to provide an additional work output prior to injection into the combustor <NUM>.

The water recovery system <NUM> draws water, schematically indicated at <NUM>, from the high energy gas flow <NUM> and communicates the recovered water to water storage tank <NUM>. The water storage tank <NUM> operates as an accumulator to provide sufficient water for operation during various engine operating conditions. A condenser/water separator <NUM> is provided downstream of the turbine section <NUM> and the evaporator <NUM>. The condenser/separator <NUM> is in communication with a cold sink, schematically indicated at <NUM> for the condenser/separator <NUM> may be, for example, ram or fan air depending on the application and/or engine configuration.

The engine <NUM> has an increased power output from the injected steam <NUM> due to an increasing mass flow through the turbine section <NUM> without a corresponding increase in work from the compressor section <NUM>. An example engine operation cycle may include up to (or more than) <NUM>% steam-air-ratios (SAR) and may be assisted by a multiple fold (e.g., 2x, 3x, etc.) increase in moisture from burning H<NUM> as the fuel.

The water recovery system <NUM> includes the water storage tank <NUM> that receives water from the condenser/water separator <NUM> and provides for the accumulation of a volume of water required for production of sufficient amounts of steam. Water recovered from the exhaust gas flow is driven by a low pressure pump <NUM> and a high pressure pump <NUM> to the evaporator <NUM>.

A water intercooling flow <NUM> may be communicated to the compressor section <NUM> to reduce a temperature of the core airflow <NUM> and increase mass flow. Reduced temperatures and increased mass flow provided by injection of water increases compressor efficiency. Water may also be used as a cooling flow <NUM> to cool cooling air flow <NUM> communicated from the compressor section <NUM> to the turbine section <NUM>.

The example compressor section <NUM> includes a low pressure compressor (LPC) <NUM> and a high pressure compressor (HPC) <NUM>. The turbine section <NUM> includes a high pressure turbine (HPT) <NUM>, an intermediate pressure turbine (IPT) <NUM>, and a low pressure turbine (LPT) <NUM>. The turbines <NUM>, <NUM> and <NUM> are coupled to a corresponding compressor section. In this disclosed example, the high pressure turbine is coupled by a high shaft <NUM> to drive the high pressure compressor <NUM>. An intermediate shaft <NUM> couples the intermediate turbine <NUM> to the low pressure compressor <NUM>.

A low shaft <NUM> is coupled to the low pressure turbine <NUM> and a gearbox <NUM> to drive the fan <NUM>. The low shaft <NUM> may further be coupled to an electric machine <NUM> that is configured to impart and/or extract power into the low shaft <NUM>. The example gearbox <NUM> is an epicyclical gear train, such as a planetary gear system, star gear system or other known gear system, with a gear reduction ratio of greater than about <NUM>.

Although the example engine <NUM> is described and shown by way of example as a three spool engine, other engine configurations, such as two-spool may also benefit from this disclosure and are within the contemplation and scope of this disclosure.

Referring to <FIG>, with continued reference to <FIG>, the example condenser/water separator <NUM> is schematically shown and includes a plurality of spiral passages <NUM> disposed within a collector <NUM>. The spiral passages <NUM> receive the high energy gas flow <NUM> along a condenser axis <NUM>. A cooling flow <NUM> is communicated from a coolant source <NUM> along an outer periphery <NUM> of the condenser <NUM>. In this example disclosed embodiment, the condenser <NUM> is circularly shaped such that the outer periphery <NUM> is an outer diameter of the spiral passages <NUM>.

The collector <NUM> surrounds the outer periphery <NUM> of the condenser <NUM> and is in communication with a water passage <NUM>. Water that is drawn out of the gas flow <NUM> flows outwardly within the collector <NUM> as schematically indicated at <NUM>. The outward flow of water <NUM> is directed to the passage <NUM> and ultimately to the water storage tank <NUM>. The collector <NUM> may include integral features that provide for guiding and directing of the water <NUM> toward outlet or outlets in communication with the passage <NUM>. The remaining gas flow <NUM> is exhausted as indicated at <NUM>.

The spiral passages <NUM> induce a spiral swirling flow of the inlet gas flow <NUM>. The spiral flow induces a centrifugal force on water within the gas flow <NUM>. As is schematically shown, swirling gas flow <NUM> within the spiral passages <NUM> has an axial component <NUM> and a transverse component <NUM>. The transverse component <NUM> is generated due to transverse pressure gradients induced by the induced swirling flow.

The condenser <NUM> includes an axial portion <NUM> that initially receives the gas flow <NUM> and a transition portion <NUM>. The transition portion <NUM> introduces a swirl into the flow that is then further enhanced by the spiral passages <NUM>. The coolant flow <NUM> may remain along an outer periphery or may be communicated to the spiral passages <NUM>. In one example embodiment, the coolant flow <NUM> and the gas flow <NUM> are maintained within separate and adjacent spiral passages. The coolant flow <NUM> absorbs heat from the gas flow <NUM> that provides for water to form a liquid condensate that is communicated as the water flow <NUM> to the passage <NUM>.

Referring to <FIG>, with continued reference to <FIG>, the example spiral passages <NUM> are formed from a plurality of layers <NUM> that spiral axially about the condenser axis <NUM>. The layers <NUM> may be thin sheets of metal that are formed to define the spiral passages in spaces therebetween. The layers <NUM> are sized to provide a desired gas flow and swirl designed to extract a predefined water flow <NUM>.

The example condenser <NUM> maybe sized to encompass all of the gas flow path aft of the turbine section <NUM> or may only take up a portion of the gas flow path. Moreover, although a single condenser <NUM> is shown and described by way of example, several condensers <NUM> maybe arranged within the gas flow path to extract water for use in the propulsion system. Moreover, those multiple condensers could be arranged about a periphery of the gas flow path.

Referring to <FIG>, another example condenser <NUM> is schematically shown and includes an intake manifold <NUM> that communicates coolant flow <NUM> and the gas flow <NUM> separately. The condenser <NUM> includes a plurality of axially extending passages <NUM> for the coolant flow <NUM>. A corresponding plurality of spiral passages <NUM> wraps about each of the axial coolant passages <NUM>. Coolant within the axial passages <NUM> cools hot gases <NUM> to transform water into a liquid condensate form and then is exhausted as shown at <NUM>. The outflow of coolant <NUM> maybe exhausted with the exhausted airflow <NUM> or communicated back to the coolant reservoir <NUM>. The liquid condensate is heavier than the gas and therefore is driven radially outward by the swirling flow imparted by the spiral passages <NUM>. The outward swirl induced in the gas and liquid drives the liquid water <NUM> through a plurality of condensate openings <NUM>. Water that is exhausted through the condensate openings <NUM> is collected by a collector <NUM> disposed about an outer periphery of the condenser <NUM>.

The spiral passages <NUM> maybe formed from sheet metal material, as a cast part or by additive manufacturing processes. Moreover, it should be appreciated that it is within the contemplation and scope of this disclosure that the example condenser <NUM> may be formed using other manufacturing and assembly processes.

Referring to <FIG>, surfaces <NUM> of the spiral passages <NUM>, <NUM> may be provided with a coating <NUM> that aids in the condensation of water from the gas flow <NUM>. In one disclosed example embodiment, the coating <NUM> comprise a hydrophilic material. In another disclosed example embodiment, the coating <NUM> comprises a hydrophobic material. Still in another disclosed example embodiment, the coating <NUM> may be a pattern of alternating sections made from a hydrophobic material and other sections including hydrophilic material to drive and gather condensate from the gas flow <NUM>.

Referring to <FIG>, surfaces <NUM> within the example condensers <NUM>, <NUM> maybe textured to enhance thermal transfer into the gas flow <NUM>. In one disclosed example, the surfaces <NUM> include a texture <NUM> formed from a plurality of raised bumps. The texture <NUM> may be configured to induce a turbulent flow near the surfaces <NUM> to enhance thermal transfer and thereby accelerate cooling and liquid extraction.

It should be appreciated, that the surfaces <NUM> and <NUM> may be portions of the layers <NUM> within the condenser <NUM> or the spiral passages <NUM> of the condenser <NUM>.

The example condensers <NUM>, <NUM> provide for the transformation of water in gas form within the gas flow into liquid water that is then separated and stored for injection back into the engine to improve overall propulsive system efficiency.

Although an example engine configuration is described by way of example, it will be appreciated that other engine configurations may include additional structures and features and are within the contemplation and scope of this disclosure.

Accordingly, the disclosed assemblies provide for the advantageous use of hydrogen fuel to improve engine efficiency and reduce carbon emission. The disclosed systems use the advantageous thermal capacity of hydrogen to maximize the recapture of heat and cool other working flows of the engine.

Claim 1:
A propulsion system for an aircraft comprising:
a core engine including a core flow path (C) where air is compressed in a compressor section (<NUM>), communicated to a combustor section (<NUM>), mixed with a hydrogen fuel and ignited to generate a high energy gas flow (<NUM>) that is expanded through a turbine section (<NUM>);
a hydrogen fuel system (<NUM>) configured to supply hydrogen fuel to the combustor (<NUM>) through a fuel flow path (<NUM>);
a condenser (<NUM>) arranged along the core flow path (C) and configured to extract water (<NUM>) from the high energy gas flow (<NUM>), the condenser (<NUM>) including a plurality of spiral passages (<NUM>) disposed in a collector (<NUM>), wherein the spiral passages (<NUM>) are configured to receive the high energy gas flow (<NUM>) and generate a transverse pressure gradient to direct water (<NUM>) out of the high energy gas flow (<NUM>) toward the collector (<NUM>); and
an evaporator (<NUM>) arranged along the core flow path (C) and configured to receive a portion of the water (<NUM>) extracted by the condenser (<NUM>) to generate a steam flow (<NUM>), wherein the steam flow (<NUM>) is injected into the core flow path (C) upstream of the turbine section (<NUM>), wherein:
the condenser (<NUM>) includes a plurality of axial passages (<NUM>) forward of the plurality of spiral passages (<NUM>), that initially receives the high energy gas flow (<NUM>), and a transition region (<NUM>) therebetween for directing the high energy gas flow (<NUM>) into the spiral passages (<NUM>); and
the collector (<NUM>) surrounds the plurality of spiral passages (<NUM>) and is in communication with a water passage (<NUM>).