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> relates to an exhaust gas treatment device that utilizes an exhaust gas energy and reduces contrails produced by a condensation following an expansion, an aircraft propulsion system having such an exhaust gas treatment device, and to a method for treating an exhaust gas stream.

A turbine engine assembly according to a first aspect of the invention is as claimed in claim <NUM>.

Some embodiments of the invention are as claimed in the dependent claims.

Although the different aspects of the invention 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 inter-cooled 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 tailoring of temperatures and pressures of the fuel flow communicated to the combustor <NUM> while maintaining the fuel flow in a gas form.

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 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 disclosed example engine embodiment <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>.

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 provided by injection of water reduces compressor work load. 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. Moreover, although the example engine <NUM> is disclosed by way of example as part of a propulsion system for an aircraft, the engine <NUM> may be provide a shaft power output utilized for driving a generator, machine or any other device.

Power generated by the steam flow <NUM> is limited by the amount of available thermal energy within the exhaust gas flow <NUM> exiting the turbine section <NUM>. The temperature of the steam may thereby limit any amount of additional power that may be obtained from the steam turbine <NUM>.

Referring to <FIG>, another example engine <NUM> is shown in a simplified schematic view and includes a superheater <NUM> to increase a temperature of the steam flow <NUM> communicated to the combustor <NUM>. Power generated by the steam turbine <NUM> is increased as compared to the previous embodiment by providing thermal communication between the water and/or steam flow at a location that is hotter than aft of the turbine section <NUM>. In one disclosed example, a superheater <NUM> is provided between the high pressure turbine <NUM> and the intermediate turbine <NUM>. The hot gas flow <NUM> between the high pressure turbine <NUM> and the intermediate turbine <NUM> is of a greater temperature and thereby able to further heat the steam flow <NUM>.

Additionally, in this example engine embodiment <NUM>, the evaporator <NUM> is located between the intermediate pressure turbine <NUM> and the low pressure turbine <NUM>. The location of the evaporator <NUM> within the turbine section <NUM> instead of aft of the turbine section provides for an increase in thermal energy that may be absorbed by the steam flow <NUM>.

A preheater <NUM> may be provided aft of the low pressure turbine <NUM> to impart thermal energy into a water flow communicated from the condenser <NUM> by way of the water storage tank <NUM>. Accordingly, water gathered in liquid form by the condenser <NUM> is initially heated by the preheater <NUM>. The initial heating of water in the preheater <NUM> is not sufficient to transform the water into steam.

The preheated water flow from the preheater <NUM> is communicated to the evaporator <NUM>. Additional thermal energy is input into the preheated water flow and transformed into a steam flow. Steam flow from the evaporator <NUM> is communicated to the superheater <NUM>. The superheater <NUM> further inputs thermal energy into the steam flow to generate a superheated steam flow <NUM>. The superheated steam flow <NUM> is expanded through the steam turbine <NUM> to generate shaft power. Steam flow exhausted from the steam turbine <NUM> is then communicated to the combustor <NUM> to increase mass flow of the high energy gas flow <NUM>.

Referring to <FIG>, another example engine <NUM> is schematically shown and includes a control valve <NUM> that controls flow through a bypass flow passage <NUM>. A controller <NUM> is programmed to govern operation of the control valve <NUM> to bypass a portion of the steam flow <NUM> to tailor engine operation according to predefined operating parameters.

As appreciated, the heating of the steam flow by gas flows within the turbine section <NUM> may reduce turbine work of turbines <NUM> and <NUM> while increasing work of steam turbine <NUM>. Removal of thermal energy from the gas flows through the turbine sections is controlled by bypassing the superheater <NUM>. The bypass passage <NUM> routes steam flow <NUM> directly from the evaporator <NUM> to the steam turbine <NUM>. Bypassing the superheater <NUM> provides for tailoring of engine operation to accommodate predefined engine operating conditions.

In this disclosed engine embodiment, the control valve <NUM> routes steam flow through the bypass passage <NUM> rather than draw thermal energy from the turbine section aft of the high pressure turbine <NUM>. Moreover, although one control valve <NUM> is shown and disclosed by way of example, a number of control valves could be utilized to route steam flows around each of the evaporator <NUM> and the preheater <NUM> to provide for tailoring of engine operation according to predefined engine operating parameters.

It should be understood that the arrangement of the superheater <NUM>, evaporator <NUM> and preheater <NUM> is shown by way of example with regard to the location within the turbine sections <NUM>, <NUM> and <NUM>. Alternate locations and combinations of the superheater <NUM>, evaporator <NUM> and the preheater <NUM> may be utilized and are within the contemplation of this disclosure. Moreover, not all of the superheater <NUM>, evaporator <NUM> and preheater <NUM> may be needed to provide a desired steam flow to the steam turbine <NUM> and the combustor <NUM>.

Referring to <FIG>, another example engine embodiment <NUM>, which does not fall under the scope of the present claims, is schematically shown and includes the evaporator <NUM> disposed between the intermediate turbine <NUM> and the low pressure turbine <NUM>. The evaporator <NUM> receives preheated water flow from the preheater <NUM>. In the evaporator <NUM>, thermal energy transforms the water flow into a steam flow <NUM> that is communicated directly to the steam turbine <NUM>.

Referring to <FIG>, another example engine embodiment <NUM> is schematically shown and includes the superheater <NUM> and the evaporator <NUM>. In this example embodiment, the superheater <NUM> disposed after the IPT <NUM> and before the LPT <NUM>. The evaporator <NUM> is disposed aft of the LPT <NUM>. In this disclosed embodiment, the thermal energy input into the waterflow aft of the LPT <NUM> is sufficient to transform the liquid water into steam. The steam flow is further heated in the superheater <NUM> and communicated to the steam turbine <NUM>.

Referring to <FIG>, another example engine embodiment is schematically shown and indicated at <NUM> and includes the superheater <NUM> and the evaporator <NUM>. In this disclosed embodiment, the superheater <NUM> is disposed between the HPT <NUM> and the IPT <NUM> and the evaporator <NUM> is arranged aft of the LPT <NUM>. The location of the superheater <NUM> is tailored to the available thermal energy and requirements for driving the steam turbine <NUM> and providing steam to the combustor <NUM>. In this disclosed example, the superheater <NUM> is disposed at a location that provides for the desired superheating of the steam flow <NUM>.

Accordingly, the example engines provide for the recapture and use of additional thermal energy by heating the steam with the gas flow at varying locations with differing and greater temperatures.

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 turbine engine assembly comprising:
a core engine (<NUM>) including a core flow path (<NUM>) where air is compressed in a compressor section (<NUM>), communicated to a combustor (<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 (<NUM>) to extract water from the high energy gas flow (<NUM>);
an evaporator (<NUM>) arranged along the core flow path (<NUM>) to input thermal energy into the water extracted by the condenser (<NUM>) to generate a steam flow (<NUM>); and
at least one superheater (<NUM>) arranged to receive the steam flow (<NUM>) from the evaporator (<NUM>) and input thermal energy for heating the steam flow (<NUM>), wherein the steam flow (<NUM>) from the at least one superheater (<NUM>) is injected into the core flow path (<NUM>) upstream of the turbine section (<NUM>),
wherein the at least one superheater (<NUM>) is in communication with the high energy gas flow (<NUM>) from the combustor (<NUM>).