Abstract: An auxiliary power unit assembly for an aircraft, including an engine assembly including an internal combustion engine, a first duct in fluid communication with an inlet of the internal combustion engine and configured to be in fluid communication with an environment of the aircraft, and a second duct configured to be in fluid communication with the environment. The second duct may be in fluid communication with an inlet of a compressor drivable by the internal combustion engine or with a compartment receiving the engine assembly. A filter extends across the first duct. The filter is removable from the first duct through an opening in a wall of the first duct, the opening accessible from an exterior of the engine assembly.

Abstract: An inlet assembly for an auxiliary power unit for an aircraft, including a duct configured to provide fluid communication from an environment of the aircraft to an inlet of an engine of the auxiliary power unit, and a filter received in and extending across the duct. The filter includes a first filter portion permeable to air, positioned across only part of the duct and defining a transverse edge in the duct; a second filter portion permeable to air and extending from the transverse edge to an end downstream of the transverse edge, and a collection member impermeable to water. The collection member extends between the downstream end and a duct wall. The first and second filter portions are non-parallel and the second filter portion and the collection member are non-parallel. An auxiliary power unit assembly and a method of feeding air to an internal combustion engine are also discussed.

Abstract: A compound engine assembly having an engine core including at least one internal combustion engine in driving engagement with an engine shaft, a compressor having an outlet in fluid communication with an inlet of the engine core and including at least one rotor rotatable about an axis coaxial with the engine shaft, the engine shaft in driving engagement with the compressor rotor, and a turbine section having an inlet in fluid communication with an outlet of the engine core and including at least one rotor engaged on a rotatable turbine shaft, the turbine shaft configured to compound power with the engine shaft. The turbine and engine shafts are parallel to and radially offset from one another, and the turbine shaft and the axis of the compressor rotor are parallel to and radially offset from one another. A method of driving a rotatable load of an aircraft is also discussed.

Abstract: In one aspect, described is a rotary engine having a purge port located rearwardly of the inlet port and forwardly of the exhaust port along a direction of the revolutions of the rotor, the purge port being in communication with the exhaust port through each of the chambers along a respective portion of each revolution, and the inlet and outlet ports being relatively located such that a volumetric compression ratio of the engine is lower than a volumetric expansion ratio of the engine.

Abstract: A rotary engine including a rotor sealingly received within an internal cavity of an outer body to define a plurality of combustion chambers having a variable volume, a pilot subchamber located in a wall of the outer body, the pilot subchamber in fluid communication with the internal cavity via at least two spaced apart transfer holes defining a flow restriction between the pilot subchamber and the internal cavity, a pilot fuel injector in fluid communication with the pilot subchamber, an ignition element configured for igniting fuel in the pilot subchamber, and a main fuel injector extending through the stator body and communicating with the cavity at a location spaced apart from the pilot subchamber. A method of combusting fuel in a rotary engine is also discussed.

Abstract: A compound engine assembly including a compressor, an engine core including at least one rotary internal combustion engine and having an inlet in fluid communication with an outlet of the compressor, a turbine section having an inlet in fluid communication with an outlet of the engine core and configured to compound power with the engine core, and an air conduit having at least one heat exchanger extending thereacross. An outer wall of the air conduit has a plurality of openings defined therethrough downstream of the heat exchanger(s), each selectively closable by a pivotable flap movable between a retracted position where the opening is obstructed and an extended position away from the opening. Each opening defines a fluid communication between the air conduit and the ambient air when the respective flap is in the extended position. A method of directing flow through a compound engine assembly is also discussed.

Abstract: A method of controlling an air intake flow in a rotary engine having primary and secondary inlet ports, including positioning the secondary inlet port rearwardly of the primary inlet port and forwardly of the exhaust port along a direction of a revolution of the rotor, providing independently closable communications between an air source and the primary and secondary inlet ports, and controlling air intake flows between the air source and the primary and secondary inlet ports. Controlling air intake flows includes simultaneously allowing the air intake flow between the primary inlet port and the air source and between the secondary inlet port and the air source. Exhaust gases of the engine are purged with the air intake flow of the secondary inlet port. A rotary engine is also discussed.

Abstract: An inlet guide assembly for a turbine receiving a pulsed flow, including a duct having an internal volume, and an inlet port, first outlet nozzle and second outlet nozzle each communicating with the internal volume. The inlet port is configured to receive at least part of the pulsed flow. The first and second outlet nozzles each define a respective nozzle area communicating between the internal volume and a flow path of the turbine. The first and second outlet nozzles are spaced from one another with the first outlet nozzle located closer to the inlet port than the second outlet nozzle relative to a flow direction through the duct, the nozzle area of the first outlet nozzle being smaller than the nozzle area of the second outlet nozzle. A compound engine assembly and method of introducing a pulsed flow into a flow path of a turbine are also discussed.

Abstract: A compound engine assembly including a common air conduit having an inlet in fluid communication with ambient air, a compressor, at least one internal combustion engine having an inlet in fluid communication with an outlet of the compressor, a turbine section having an inlet in fluid communication with an outlet of the at least one internal combustion engine, the turbine section configured to compound power with the at least one internal combustion engine, and at least one heat exchanger in fluid communication with the common air conduit, each of the at least one heat exchanger configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the common air conduit circulating therethrough. The compressor has an inlet in fluid communication with the common air conduit upstream of the at least one heat exchanger. The internal combustion engine may be a reciprocating engine.

Abstract: An intake assembly for a compressor providing compressed air to an internal combustion engine core, including an air conduit having at least one heat exchanger extending thereacross, an intake plenum for the compressor, a first intake conduit connected to the air conduit upstream of the heat exchanger(s), a second intake conduit connected to the air conduit downstream of the heat exchanger(s), and a selector valve configurable between a first configuration to allow a fluid communication between the intake plenum and the air conduit through the first intake conduit and a second configuration to prevent the fluid communication through the first intake conduit. Fluid communication between the intake plenum and the air conduit through the second intake conduit is allowed at least when the selector valve is in the second configuration. An engine assembly and method of supplying air to a compressor are also discussed.

Abstract: A compound engine assembly with an engine core including at least one internal combustion engine, a compressor, and a turbine section where the turbine shaft is configured to compound power with the engine shaft. The turbine section may include a first stage turbine and a second stage turbine. The turbine shaft is rotationally supported by a plurality of bearings all located on a same side of the compressor rotor(s) and all located on a same side of the turbine rotor(s), for example all located between the compressor rotor(s) and the turbine rotor(s), such that the compressor rotor(s) and the turbine rotor(s) are cantilevered. A method of driving a rotatable load of an aircraft is also discussed.

Abstract: A rotary engine where the rotor cavity has a peripheral inner surface having a peritrochoid configuration defined by a first eccentricity and the rotor has a peripheral outer surface having a peritrochoid inner envelope configuration defined by a second eccentricity larger than the first eccentricity. Also, a rotary engine where the rotor cavity has a peripheral inner surface having a peritrochoid configuration defined by an eccentricity, and a rotor with a peripheral outer surface between adjacent ones of the apex portions being inwardly offset from a peritrochoid inner envelope configuration defined by the eccentricity. The engine may have an expansion ratio with a value of at most 8. The rotary engine may be part of a compound engine system.

Abstract: An engine assembly including an internal combustion engine, an impulse turbine, and an exhaust pipe providing fluid communication between the exhaust port of the internal combustion engine and the flow path of the turbine. The exhaust pipe terminates in a nozzle. A ratio Vp/Vd between the pipe volume Vp and the displacement volume Vd of the internal combustion engine is at most 1.5. A minimum value of a cross-sectional area of the exhaust pipe is defined at the nozzle. In one embodiment, a ratio An/Ae between the minimum cross-sectional area An and the cross-sectional area Ae of the exhaust port of the internal combustion engine is at least 0.2. A method of compounding at least one internal combustion engine is also discussed.

Abstract: A method of controlling an air intake flow in a rotary engine having primary and secondary inlet ports, including positioning the secondary inlet port rearwardly of the primary inlet port and forwardly of the exhaust port along a direction of a revolution of the rotor, and controlling air intake flows communicating between an air source and the primary and secondary inlet ports. During engine start-up, a primary valve is closed to prevent the intake air flow between the primary inlet port and the air source and a secondary valve is opened to allow the intake air flow between the secondary inlet port and the air source. A rotary engine defining different compression ratios through actuation of a valve is also discussed.

Abstract: A compound engine system includes a rotary engine with rotating chambers, a compressor section in successive communication with the rotating chambers, and a turbine section in successive communication with the rotating chambers. The turbine section has an output shaft. The output shaft and the engine shaft are drivingly engaged to each other and wherein the turbine section has a power output corresponding to from 20% to 35% of a total power output of the compound engine system. A method of compounding power in a compound engine system is also discussed.

Abstract: A compound engine assembly including an air conduit having an inlet in fluid communication with ambient air around the compound engine assembly, a compressor having an inlet in fluid communication with the air conduit, an engine core including at least one rotary internal combustion engine and having an inlet in fluid communication with an outlet of the compressor, a turbine section having an inlet in fluid communication with an outlet of the engine core and configured to compound power with the engine core; and at least one heat exchanger in fluid communication with the air conduit, each heat exchanger configured to circulate a fluid of the engine assembly in heat exchange relationship with an airflow from the air conduit circulating therethrough. A method of supplying air to a compound engine assembly is also discussed.

Abstract: A compound engine assembly for use as an aircraft auxiliary power unit, having an engine core including internal combustion engine(s) in driving engagement with an engine shaft, a generator having a generator shaft directly engaged to the engine shaft such as to be rotatable at a same speed, a compressor having an outlet in communication with the engine core inlet, and a turbine section having an inlet in communication with the engine core outlet and configured to compound power with the engine core. The turbine section may include a first stage turbine having an inlet in communication with the engine core outlet, and a second stage turbine having an inlet in communication with the first stage turbine outlet. A method of providing electrical power to an aircraft is also discussed.

Abstract: An engine assembly for use as an aircraft auxiliary power unit, having internal combustion engine(s) in driving engagement with an engine shaft, a generator having a generator shaft directly engaged to the engine shaft such as to be rotatable at a same speed, a compressor having an outlet in communication with the internal combustion engine inlet, and a turbine having an inlet in communication with the internal combustion engine outlet. The turbine may be a first stage turbine, and the assembly may include a second stage turbine having an inlet in communication with the first stage turbine outlet. A method of providing electrical power to an aircraft is also discussed.

Abstract: A directional control system for a rotorcraft having a tail boom including a no-tail-rotor apparatus configured to control rotorcraft yaw using forced air ejected from the tail boom and a duct configured to deliver the forced air to the no-tail-rotor apparatus. The directional control system comprises a heat exchanger having air passages and fluid passages, the air passages in fluid communication with the duct, the fluid passages in heat exchange relationship with the air passages and configured for receiving a cooling fluid, and a forced air driver in fluid communication with the duct for driving the forced air through the duct to the no-tail-rotor apparatus. Methods of providing directional control in a rotorcraft are also discussed.

Abstract: A compound engine system including a Wankel engine having a recess defined in the peripheral wall of the rotor in each of the three rotating chambers, the recess having a volume of more than 5% of the displacement volume of the chambers. The expansion in the turbine section compensates for the relatively low expansion ratio of the rotary engine.