Patent Description:
Gas turbine engines (used in propulsion and power applications and broadly inclusive of turbojets, turboprops, turbofans, and the like) power ECS in aircraft. One category of ECS are known as air cycle systems (ACS), sometimes identified by its air cycle machine (ACM) subsystem. Another group of ECS are known as vapor cycle systems (VCS).

In an example ACS, compressor bleed air is bled from an engine at an intermediate stage of compression. The compression has raised the temperature. Thus an example bleed is at a temperature of about <NUM> and a pressure of about 520kPa. This may be distinguished from an in-flight external environmental condition of a temperature of about -<NUM> and a pressure of about 60kPa.

The bleed flowpath first passes through a primary heat exchanger (an air-to-air heat exchanger where the bleed flow is cooled by an environmental air flow such as a ram air flow). The bleed air exits the primary heat exchanger at a temperature of about <NUM>.

Downstream of the primary heat exchanger, the bleed air is compressed by the centrifugal compressor of the ACM. The compression raises both temperature and pressure of the bleed flow. Bleed air exits the compressor at a temperature of about <NUM> and a pressure of about 830kPa.

Downstream of the compressor, the bleed flowpath passes through a secondary heat exchanger (an air-to-air heat exchanger where the bleed flow is cooled by an environmental air flow such as a ram air flow - optionally the same air flow cooling the primary heat exchanger). The bleed air exits the secondary heat exchanger at a temperature of about <NUM>.

Downstream of the secondary heat exchanger, the bleed air is expanded by the turbine of the ACM to mechanically drive the compressor. The expansion in the turbine lowers both temperature and pressure of the bleed flow. Bleed air exits the turbine at a temperature of about <NUM> and a pressure of about 410kPa.

Downstream of the turbine, the bleed flowpath passes through a water collector (e.g., a can-type collector where swirl vanes centrifuge water from the airflow and the centrifuged water is drained). An example can-type water collector is shown in <CIT>. A mesh or screen upstream of the collector helps coalesce the water droplets. An example of such a coalescing collector is shown in <CIT>.

The bleed air exits the water collector at a temperature of about <NUM>. Collected water may be dumped overboard directly or injected into the ram-air flow to enhance cooling in the primary and secondary heat exchangers. In other systems, the water collector is upstream of the turbine (e.g., immediately downstream of the secondary heat exchanger).

The cooled air may directly be used to cool a load such as avionics or may be blended with additional warmer air (e.g., an additional bleed or a bypass portion of the bleed) to provide cabin air services (e.g. pressurizing the cabin and providing heating or cooling).

In a condensing/reheat system variation on the particular example ACS of a water collector upstream of the turbine: <NUM>) a reheat heat exchanger (reheater) heat rejecting/donor leg followed by a condenser heat rejecting/donor leg are added between the secondary heat exchanger and the water collector; <NUM>) the reheater heat recipient/receiving leg is added downstream of the water collector; and <NUM>) the turbine is moved to between the reheater heat recipient/receiving leg and the condenser heat recipient/receiving leg.

For example, <CIT>, of Zywiak, entitled "Dual turbine bootstrap cycle environmental control system", and issued September <NUM>, <NUM>, discloses a particular condensing/reheat ACS. Heat receiving legs of a reheater and a condenser intervene between the secondary heat exchanger and the water collector upstream of a first turbine stage. Heat rejecting/donor legs of the condenser and reheater intervene between the first turbine stage and a second turbine stage.

Depending upon the nature of the aircraft, many of several cooling loads may predominate. These include passenger cabin climate control and avionics cooling. In passenger aircraft, the former predominate. In military aircraft, the latter predominate.

Cooling capacity, especially for ACS, generally comes at the expense of engine bleed air, and thus either specific fuel consumption (SFC) or thrust.

<CIT> discloses an aircraft propulsion system as set forth in the preamble of claim <NUM>.

<CIT> discloses a fan-driven turbine system.

<CIT> discloses a control apparatus and a method for a gas-turbine engine.

According to an aspect of the present invention, there is provided an aircraft propulsion system in accordance with claim <NUM>.

Optionally, the turbine drives only the propulsion fan.

Optionally, a valve-controlled bypass flowpath bypasses the turbine from downstream of the reheater heat exchanger second leg to upstream of the condenser heat exchanger second leg.

Optionally, the primary heat exchanger provides heat exchange between the bleed flowpath and a ram air flowpath.

Optionally, the load is a passenger cabin air source.

Optionally: the reheater heat exchanger is a plate-fin heat exchanger; the condenser heat exchanger is a plate-fin heat exchanger; and the water collector is a can-type collector.

Optionally, the ECS does not have a compressor along the bleed flowpath.

Optionally, the ECS does not have any other turbine along the bleed flowpath.

Optionally, the turbine is a single stage turbine the ECS does not have a secondary heat exchanger along the bleed flowpath.

Optionally, an aircraft includes the aircraft propulsion system of and further comprises: a fuselage; a wing extending from the fuselage; an engine pylon mounting an engine nacelle of the gas turbine engine to the fuselage; and a supplemental propulsion pylon mounting the turbine and propulsion fan to the fuselage.

Optionally, the aircraft further comprises a ram air flowpath in heat exchange relation with the bleed flowpath.

Optionally: the engine pylon mounts the engine nacelle to the fuselage via the wing; and the supplemental propulsion pylon mounts the turbine and propulsion fan to the fuselage via the wing.

In a further embodiment of any of the foregoing, additionally and/or alternatively, an aircraft including the aircraft propulsion system further comprises a ram air flowpath in heat exchange relation with the bleed flowpath.

Optionally, one or more of: the ECS does not have a compressor along the bleed flowpath; the turbine drives only the propulsion fan; the ECS heat exchange relation is at a primary heat exchanger and the ECS does not have a secondary heat exchanger along the bleed flowpath and ram air flowpath; and an electric fan drives air along the ram air flowpath.

A method for using the aircraft propulsion system in an aircraft comprises: running the gas turbine engine to draw in air, compress the air in a compressor section, mix the air with fuel, combust the mixed air and fuel forming combustion products, expand the combustion products in a turbine section to drive the compressor section, expel the combustion products to produce thrust to propel flight of the aircraft; bleeding a bleed flow of compressed air from the gas turbine engine; passing the bleed flow along the bleed flowpath; and the bleed flow driving the turbine to drive the propulsion fan and help propel the flight of the aircraft.

Optionally, the method of further comprises bypassing the turbine to control air temperature delivered to the load.

Optionally, a controller controls the engine and the bypassing to provide a desired net thrust.

A cooling system is proposed that combines an air cycle system (ACS) with a propulsion fan (supplemental propulsion fan supplementing the propulsion provided by the engine). The example air cycle machine (ACM) in the ACS has a single turbine mechanically coupled via a shaft to the propulsion fan. The ACS architecture is like a typical condensing/reheat cycle, except there is not a compressor or secondary heat exchanger in the system so that the turbine powers the propulsion fan instead of the omitted compressor. The secondary heat exchanger may be omitted because of the lack of temperature rise of the omitted compressor. The compressor and secondary heat exchanger elimination may contribute to a smaller and/or lighter ACS than a baseline ACS or other alternative.

The propulsion fan is located and sized to provide supplemental propulsion to the aircraft using the energy extracted from the ACS via the turbine. This architecture may directly provide useful propulsion to the aircraft while creating needed cooling. In various implementations, this may result in a smaller ACS and/or improved SFC relative to a baseline or other alternative.

<FIG> shows an aircraft hybrid environmental control system (ECS) and supplemental propulsion system <NUM>. The basic ECS is an air cycle system (ACS) <NUM> wherein the airflow powers the supplemental propulsion system <NUM>. The system includes an air flowpath <NUM> which is a bleed flowpath passing an air flow <NUM> (bleed flow) from a compressor bleed on an aircraft engine (discussed further below). The air flowpath <NUM> may be branching and may be an open flowpath ultimately venting out of the aircraft. Several examples are discussed below. <FIG> flow arrows show flow directions of a normal operating mode with the engine bleed providing both power for the supplemental propulsion system <NUM> and one or more cooling loads <NUM>, <NUM>, <NUM>. The air flowpath may be bounded by ducts linking the various heat exchangers and similar components discussed further below.

The supplemental propulsion system <NUM> includes the propulsion fan <NUM> coupled to the turbine <NUM> to be driven by the turbine (e.g., co-spooled via a shaft <NUM> supported for rotation about an axis in common via multiple bearings (not shown)). A rotational speed sensor <NUM> measures speed of the propulsion fan. An example sensor <NUM> is an optical encoder (e.g., with an encoder wheel mounted to the shaft <NUM>). Alternatives are magnetic encoders.

The example turbine <NUM> is a centrifugal turbine with radial inlet and axial outlet.

The ACS <NUM> has, sequentially along the air flowpath <NUM> (namely a trunk <NUM> of the air flowpath): an inlet <NUM> at an engine bleed port; a primary heat exchanger <NUM>, namely a heat rejecting/donor leg <NUM> thereof; a reheat heat exchanger (reheater) <NUM>, namely a heat rejecting/donor leg <NUM> thereof; a heat rejection heat exchanger (e.g., condenser) <NUM> namely, a heat rejecting/donor leg <NUM> thereof; a water collector <NUM>; the reheater <NUM> heat receiving/recipient leg <NUM>; the turbine <NUM> of the propulsion system <NUM>; and the condenser <NUM> heat receiving/recipient leg <NUM>. The example air flowpath <NUM> then branches to the loads <NUM>, <NUM>, <NUM>. Thus, this example omits the compressor and secondary heat exchanger from the typical condensing/reheat cycle ACS.

The example load branches include a branch <NUM> feeding the load <NUM>. The example load <NUM> is air-cooled equipment (e.g., avionics or other electronics). In one example, the air-cooled equipment is in an equipment bay in the fuselage and the bleed air along the branch <NUM> is flowed through the equipment bay otherwise unconstrained and vents overboard from the equipment bay. In alternative embodiments, the air flow along the branch <NUM> may pass constrained through a heatsink to remove/receive heat from the equipment. In the example, a flow control valve <NUM> is positioned along the branch <NUM> under control of a control system (controller) <NUM> which may represent existing control equipment such as a full authority digital engine control (FADEC). Integrating functions of controlling the ACS with the FADEC of the associated engine is advantageous in that it allows the FADEC to control net thrust of the engine and the propulsion fan of the ACS. Alternatively, the controller <NUM> may represent a conventional computer-based or microcontroller-based ACS controller in communication with the FADEC so as to allow the FADEC to communicate with the ACS controller. The controller may be coupled directly or indirectly to various sensors, input devices, controlled components, and the like via hardwired analog or digital lines including wires or fiber optics.

The example valve <NUM> is a continuous control throttle valve such as a butterfly valve (e.g., as opposed to a bi-static valve such as a solenoid and/or pulse-width-modulated (PWM) valve). Example actuators for this valve and the other valves include pneumatic actuators and a stepper motors.

The example remaining loads <NUM> and <NUM> represent cabin and air services such as cockpit cooling and pressurization <NUM> and cabin cooling and pressurization <NUM>. They may be fed via respective sub-branches <NUM> and <NUM> off of a branch <NUM> which branches in parallel with the branch <NUM>. The branches <NUM> and <NUM> may have valves <NUM> and <NUM> (e.g., otherwise similar to the valve <NUM> discussed above).

In addition to the load branches, the ACS <NUM> may comprise one or more bypasses. <FIG> shows bypass flowpaths (bypasses) <NUM> and <NUM>. The bypass <NUM> bypasses relatively warm engine bleed air from a location in the air flowpath trunk <NUM> upstream of the primary heat exchanger <NUM> to a location for mixing with one or more of the loads. The example mixing location is along the branch <NUM>. As noted above regarding the prior art, this so-called trim branch/bypass <NUM> allows mixing of the relatively warm bleed with the relatively cool air exiting the condenser <NUM> heat receiving/recipient leg <NUM> along the branch <NUM>. The control of the proportions of the mixing allow control over temperature of air introduced to the loads <NUM> and <NUM> and thus allow control over cockpit temperature and cabin temperature. In the illustrated example, the overall bleed flow from the engine is controlled by a valve <NUM> (e.g., otherwise similar to the valve <NUM>) in the trunk <NUM> upstream of the trim bypass <NUM> and flow along the trim bypass <NUM> is controlled by a valve <NUM> (e.g., otherwise similar to the valve <NUM>) in the trim bypass.

An additional bypass flowpath (bypass) <NUM> is a turbine bypass flowpath extending from a location in the air flowpath trunk <NUM> between the reheater <NUM> heat receiving/recipient leg <NUM> and turbine <NUM> inlet to a location between the turbine outlet and the condenser <NUM> heat receiving/recipient leg <NUM> inlet. An example turbine bypass <NUM> has a valve <NUM> (e.g., otherwise similar to the valve <NUM>).

The example ACS also includes a check valve <NUM> in the branch <NUM> upstream of the junction with the trim bypass <NUM>. The check valve <NUM> is oriented to prevent a reverse flow. In operation, there will be a pressure drop across the turbine <NUM> when the turbine is running. Although it may be desirable to moderate cockpit and cabin temperature via blending of warm bleed air, this may not be the case with the air-cooled equipment <NUM>. The check valve <NUM> thus prevents the trim air from warming the main bleed air delivered to the air-cooled equipment <NUM>. Temperature of the air flow exiting the condenser heat receiving/recipient leg <NUM> to the branch <NUM> and the branch <NUM> upstream of the junction with the trim bypass <NUM> may be controlled via bypassing the turbine <NUM> using the turbine bypass valve <NUM> with increased bypass flow along the turbine bypass <NUM> increasing temperature and decreased bypass flow decreasing temperature.

Additionally, throughout the system there may be various temperature sensors and pressure sensors. Example temperature sensors are thermocouples or thermistors. Example pressure sensors are piezoelectric diaphragm sensors. <FIG> shows a basic example of a temperature sensor <NUM> and pressure sensor <NUM> between the reheater and turbine (measuring turbine inlet conditions); a temperature sensor <NUM> and a pressure sensor <NUM> between the turbine outlet and condenser heat receiving/recipient leg inlet (measuring conditions of the blended flow from the turbine outlet and turbine bypass); a temperature sensor <NUM> in the branch <NUM> (measuring air temperature delivered to the load <NUM>); and a temperature sensor <NUM> in the branch <NUM> downstream of the trim bypass (measuring blended air temperatures for the loads <NUM> and <NUM>).

Thus, an example bleed is at a temperature of about <NUM> and a pressure of about 520kPa at the bleed inlet <NUM>. The example primary heat exchanger <NUM> is an air-air heat exchanger, more particularly a brazed plate-fin heat exchanger where the heat receiving/recipient leg is ambient air of a ram flow <NUM> along a ram air flowpath <NUM>. The example ram air flowpath <NUM> extends from a ram air inlet <NUM> to a ram air outlet <NUM>. These may be respective ports on the fuselage or on a wing. The ram air flowpath <NUM> passes downstream through the heat receiving/recipient leg <NUM> of the primary heat exchanger and through an optional electric fan <NUM> (e.g., driven by an electric motor drawing current from an engine-integrated generator or an accessory generator - not shown) before exiting the outlet <NUM>. The bleed air exits the primary heat exchanger heat rejecting/donor leg <NUM> at an example temperature of about <NUM>.

The example reheat heat exchanger (reheater) <NUM> is a brazed plate-fin heat exchanger. The bleed air exits the reheater heat rejecting/donor leg <NUM> at an example temperature of about <NUM>.

The example heat rejection heat exchanger (e.g., condenser) <NUM> is a brazed plate-fin heat exchanger. The bleed air exits the condenser heat rejecting/donor leg <NUM> at an example temperature of about <NUM>.

The example water collector <NUM> is a can-type collector (e.g., as in the '<NUM> patent). The bleed air exits the water collector at an example temperature of about <NUM>. The bleed air exits the reheater heat receiving/recipient leg <NUM> at an example temperature of about <NUM>.

Bleed air exits the turbine <NUM> at an example temperature of about <NUM> and an example pressure of about 170kPa. The bleed air exits the condenser heat recipient leg <NUM> at an example temperature of about <NUM>.

<FIG> schematically shows an aircraft <NUM> including the hybrid ECS and supplemental propulsion system <NUM>. The example aircraft <NUM> has a fuselage <NUM>. The fuselage extends from a nose <NUM> to a tail <NUM>. A main wing <NUM> extends laterally outward from the fuselage on left and right sides. A horizontal stabilizer <NUM> and vertical stabilizer <NUM> are proximate the tail aft of the main wing. Control surface details (not shown) may be conventional. <FIG> schematically shows separate ECS associated with the respective engines with each having a ram air inlet <NUM> and a ram air outlet <NUM>. The main components of each system are contained in a bay <NUM> in the fuselage (e.g., including the various heat exchangers <NUM>, <NUM>, and <NUM>).

Other aircraft configurations exist including delta wing and delta canard configurations among other configurations lacking the traditional combination of vertical stabilizer and horizontal stabilizer.

The example aircraft has engines 720A, 720B positioned in respective nacelles <NUM> on respective wing pylons <NUM>. Each engine has its own associated ACM with turbine <NUM> (and optionally propulsion fan <NUM>) in an adjacent nacelle <NUM> on an adjacent pylon <NUM> (e.g., inboard of the associated engine nacelle and pylon). In the illustrated example, the nacelle contains the turbine <NUM> and the propulsion fan <NUM> is an unducted fan.

There may be two completely separate ACS or the ACS may share certain components such as combining to feed the cabin, cockpit, or air cooled equipment. The ACS may also be configured to allow the two ACS to both receive bleed air from the same engine in certain abnormal conditions such as a failure of the other engine. In any such implementation, appropriate valves, cross-linking ducts or piping, and the like may be provided to allow the particular operation and isolate any damage that would cause leakage.

Alternative engine nacelles and/or supplemental propulsion nacelles are mounted via their pylons directly to the fuselage rather than via the wing. In alternative variations, the supplemental propulsion system pylon may be omitted and the turbine mounted directly in the wing or fuselage. For example, the turbine may have a sufficiently small diameter to fit within the wing and not require a separate pylon and nacelle (e.g., leaving the propulsion fan <NUM> external to the wing ahead of the leading edge or aft of the trailing edge).

<FIG> shows an example gas turbine engine <NUM> (representing the engines 720A and 720B) as a two-spool turbofan engine. The engine <NUM> has an engine case <NUM> surrounding a centerline or central longitudinal axis <NUM>. An example engine has a fan section <NUM> including a fan <NUM> within a fan case <NUM>. The example engine includes an inlet <NUM> at an upstream end of the fan case receiving an inlet flow along an inlet flowpath <NUM>. The fan <NUM> has one or more stages <NUM> of fan blades. Downstream of the fan blades, the flowpath <NUM> splits into an inboard portion <NUM> being a core flowpath and passing through a core of the engine and an outboard portion <NUM> being a bypass flowpath exiting an outlet <NUM> of the fan case.

The core flowpath <NUM> proceeds downstream to an engine outlet <NUM> through one or more compressor sections, a combustor, and one or more turbine sections. The example engine has two axial compressor sections and two axial turbine sections, although other configurations are equally applicable. From upstream to downstream there is a low pressure compressor section (LPC) <NUM>, a high pressure compressor section (HPC) <NUM>, a combustor section <NUM>, a high pressure turbine section (HPT) <NUM>, and a low pressure turbine section (LPT) <NUM>. Each of the LPC, HPC, HPT, and LPT comprises one or more stages of blades which may be interspersed with one or more stages of stator vanes.

In the example engine, the blade stages of the LPC and LPT are part of a low pressure spool mounted for rotation about the axis <NUM>. The example low pressure spool includes a shaft (low pressure shaft) <NUM> which couples the blade stages of the LPT to those of the LPC and allows the LPT to drive rotation of the LPC. In the example engine, the shaft <NUM> also drives the fan. In the example implementation, the fan is driven via a transmission (not shown, e.g., a fan gear drive system such as an epicyclic transmission) to allow the fan to rotate at a lower speed than the low pressure shaft.

The example engine further includes a high pressure shaft <NUM> mounted for rotation about the axis <NUM> and coupling the blade stages of the HPT to those of the HPC to allow the HPT to drive rotation of the HPC. In the combustor <NUM>, fuel is introduced to compressed air from the HPC and combusted to produce a high pressure gas which, in turn, is expanded in the turbine sections to extract energy and drive rotation of the respective turbine sections and their associated compressor sections (to provide the compressed air to the combustor) and fan. The example bleed port forming the inlet <NUM> is an inter-section bleed between LPC and HPC. Alternatives are inter-stage bleeds within the LPC.

In use, the bleed valve <NUM> just upstream of the primary heat exchanger <NUM> controls overall pressure into the system and in general, the cooling capacity of the package. The trim valve <NUM> from the engine bleed to the cabin and cockpit tapoffs provides warm air when needed for temperature control. The turbine bypass valve <NUM> provides the ability to control the mixed out temperature downstream of the turbine.

Component materials and manufacture techniques and assembly techniques may be otherwise conventional for ACS. Additionally, conventional metal or composite manufacture techniques may be used for the supplemental fans.

In a control example, the controller <NUM> provides feedback control over inlet pressure to the ACS via control of the valve <NUM>. The controller <NUM> receives a signal from the pressure sensor <NUM> that relates to the pressure just downstream of valve <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the target pressure or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like. Typically this will at least include altitude. The controller <NUM> compares the signal from the pressure sensor <NUM> to the reference value. The controller <NUM> sends a signal to the actuator for valve <NUM> to increase valve position (open the valve more) if the signal from pressure sensor <NUM> is less than the reference value. Controller <NUM> sends a signal to the actuator for valve <NUM> to decrease valve position (close the valve more) if the signal from pressure sensor <NUM> is greater than the reference value.

In an alternative control example, the controller <NUM> controls the mass flow rate into the system instead of the pressure into the system. The controller <NUM> receives a signal from mass flow rate sensor <NUM> that relates to the mass flow rate just downstream of the valve <NUM>. Example flow sensors are Venturi-type sensors or hot wire anemometers. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the mass flow rate or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like. Typically this will at least include altitude. The controller <NUM> compares the signal from the mass flow rate sensor <NUM> to the reference value. The controller <NUM> sends a signal to the actuator for the valve <NUM> to increase valve position (open the valve more) if the signal from the mass flow rate sensor <NUM> is less than the reference value. The controller <NUM> sends a signal to the actuator for valve <NUM> to decrease valve position (close the valve more) if the signal from mass flow rate <NUM> is greater than the reference value.

The controller <NUM> controls the air temperature into the cold inlet of condenser <NUM>. The controller <NUM> receives a signal from temperature sensor <NUM> that relates to the air temperature at the cold inlet of condenser <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the temperature or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like. Typically this will at least include altitude. The reference value may correspond to a target temperature selected to be cold enough to provide a required cooling capacity while not risking icing/freezing. The controller <NUM> compares the signal from the temperature sensor <NUM> to the reference value. The controller <NUM> sends a signal to the actuator for the valve <NUM> to increase valve position (open the valve more) if the signal from the temperature sensor <NUM> is less than the reference signal. The controller <NUM> sends a signal to the actuator for the valve <NUM> to decrease valve position (close the valve more) if the signal from temperature sensor <NUM> is greater than the reference value. Optionally, a transient defrost mode may be actuated with a higher target either intermittently or responsive to sensed icing/freezing.

The controller <NUM> controls the air temperature to cockpit <NUM> and cabin <NUM>. The controller <NUM> receives a signal from the temperature sensor <NUM> that relates to the temperature of the air flowing to cockpit <NUM> and cabin <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the temperature or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like. Typically this will at least include altitude. The pilot may make use of a manual override function to set a higher reference value for additional heating when desired. The controller <NUM> sends a signal to the actuator for the valve <NUM> to increase valve position (open the valve more) if the signal from the temperature sensor <NUM> is less than the reference value. The controller <NUM> sends a signal to the actuator for valve <NUM> to decrease valve position (close the valve more) if the signal from the temperature sensor <NUM> is greater than the reference signal.

The controller <NUM> controls the mass flow rate to provide cooling to equipment <NUM>. The controller <NUM> receives signals from the temperature sensor <NUM> and mass flow rate sensor <NUM> that relate to the temperature and mass flow rate, respectively, to equipment <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the mass flow rate or proxy) based on parameters such as altitude, external temperature, external pressure, airspeed, and the like. Typically this will at least include altitude, as well as the signal from the temperature sensor <NUM>. The controller <NUM> sends a signal to the actuator for valve <NUM> to increase valve position (open the valve more) if the signal from mass flow rate sensor <NUM> is less than the reference signal. The controller <NUM> sends a signal to the actuator for the valve <NUM> to decrease valve position (close the valve more) if the value from the mass flow rate sensor <NUM> is greater than the reference value.

The controller <NUM> controls the mass flow rate to provide conditioned air to cockpit <NUM>. The controller <NUM> receives signals from the temperature sensor <NUM> and the mass flow rate sensor <NUM> that relate to the temperature and mass flow rate, respectively, to cockpit <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the mass flow rate or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like (typically this will at least include altitude), as well as the signal from the temperature sensor <NUM>. The controller <NUM> sends a signal to the actuator for the valve <NUM> to increase valve position (open the valve more) if the signal from mass flow rate sensor <NUM> is less than the reference value. The controller <NUM> sends a signal to the actuator for the valve <NUM> to decrease valve position (close the valve more) if the signal from the mass flow rate sensor <NUM> is greater than the reference value. Additional parameters may reflect air quality/refresh standards for crew health. Such standards restrict flow rate options. Thus, cockpit and cabin cooling may be more controlled by the temperature of the delivered air than flow rate.

The controller <NUM> controls the mass flow rate to provide conditioned air to the cabin <NUM>. The controller <NUM> receives signals from the temperature sensor <NUM> and mass flow rate sensor <NUM> that relate to the temperature and mass flow rate, respectively, to the cabin <NUM>. The controller <NUM> is pre-programmed with a look-up table or equation that provides a reference value (the mass flow rate or proxy) based on parameters such as one or more of altitude, external temperature, external pressure, airspeed, and the like (typically this will at least include altitude), as well as the signal from the temperature sensor <NUM>. The controller <NUM> sends a signal to the actuator for the valve <NUM> to increase valve position (open the valve more) if the signal from the mass flow rate sensor <NUM> is less than the reference value. The controller <NUM> sends a signal to the actuator for the valve <NUM> to decrease valve position (close the valve more) if the signal from the mass flow rate sensor <NUM> is greater than the reference value. Additional parameters may reflect air quality/refresh standards for passenger health. Such standards restrict flow rate options. Thus, cockpit and cabin cooling may be more controlled by the temperature of the delivered air than flow rate.

The controller <NUM> controls the operation of the associated main propulsion engine 720A, 720B. The controller <NUM> receives signals from temperature sensor <NUM>, pressure sensor <NUM>, temperature sensor <NUM>, pressure sensor <NUM>, mass flow rate signal <NUM>, and rotational speed sensor <NUM>. The controller <NUM> uses these inputs along with pre-programmed look-up tables and/or functions of turbine performance to estimate the work extracted via turbine <NUM>. The controller <NUM> further uses parameters such as altitude, external temperature, external pressure, airspeed, and the like to estimate the propulsive thrust from propulsion fan <NUM>. The controller <NUM> then makes necessary adjustments to control effectors on the main propulsion engine to achieve the overall propulsive thrust that is desired from that pairing of engine and propulsion fan.

More complex control algorithms may interrelate the various controlled parameters discussed above (or others).

Claim 1:
An aircraft propulsion system (<NUM>) comprising:
a gas turbine engine (<NUM>);
an environmental control system (ECS) (<NUM>); and
a bleed flowpath (<NUM>) from the gas turbine engine (<NUM>) through the ECS (<NUM>),
and further comprising:
a turbine (<NUM>) along the bleed flowpath (<NUM>); and
a propulsion fan (<NUM>) mechanically coupled to the turbine (<NUM>) to be driven by the turbine (<NUM>),
characterized in that the ECS (<NUM>) has, sequentially along the bleed flowpath (<NUM>):
a primary heat exchanger (<NUM>);
a first leg (<NUM>) of a reheater heat exchanger (<NUM>);
a first leg (<NUM>) of a condenser heat exchanger (<NUM>);
a water collector (<NUM>);
a second leg (<NUM>) of the reheater heat exchanger (<NUM>) in heat exchange relation with the first leg (<NUM>) of the reheater heat exchanger (<NUM>);
the turbine (<NUM>);
a second leg (<NUM>) of the condenser heat exchanger (<NUM>) in heat exchange relation with the first leg (<NUM>) of the condenser heat exchanger (<NUM>); and
a load (<NUM>; <NUM>; <NUM>).