An aircraft propulsion system comprising a reciprocating liquid cooled engine housed within the fuselage driving twin fuselage mounted ducted-fans is disclosed. The propulsion system may be liquid cooled with a liquid cooled exhaust and at least one turbocharger. The ducted-fans may run fan blade tip speeds of up to 97% Mach driven by a near constant RPM engine through a continuously variable transmission. The propulsion system may be low noise and may meet environmental standards typical in the automotive industry.

The cooling device according to the present invention includes an electric water pump for circulating cooling water through an internal combustion engine of a vehicle, and controls the discharge flow rate of the electric water pump as follows. Until the cooling water temperature. TW reaches a warm-up completion determination temperature, the cooling device increases the discharge flow rate along with an increase of the cooling water temperature TW. After the cooling water temperature TW reaches the warm-up completion determination temperature, the cooling device controls the discharge flow rate so as to bring the combustion chamber wall temperature TCYL toward a target temperature. Thereby, the cooling device can warm up the internal combustion engine more efficiently, and improve the combustion performance of the internal combustion engine after the completion of warm-up.

The cooling device according to the present invention includes an electric water pump for circulating cooling water through an internal combustion engine of a vehicle, and controls the discharge flow rate of the electric water pump as follows. Until the cooling water temperature. TW reaches a warm-up completion determination temperature, the cooling device increases the discharge flow rate along with an increase of the cooling water temperature TW. After the cooling water temperature TW reaches the warm-up completion determination temperature, the cooling device controls the discharge flow rate so as to bring the combustion chamber wall temperature TCYL toward a target temperature. Thereby, the cooling device can warm up the internal combustion engine more efficiently, and improve the combustion performance of the internal combustion engine after the completion of warm-up.

A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes or forms a chamber delimited by a wall arrangement forming an inlet opening and an outlet opening. A cooling device is arranged on the piston receptacle for cooling the wall arrangement. The cooling device includes or forms a cooling channel arranged radially outside on the wall arrangement. The cooling channel has first and second cooling regions axially on opposing sides of the outlet opening. The piston receptacle includes or forms an outlet chamber, arranged outside on the wall arrangement, for exhaust gas exiting via the outlet opening. The cooling channel has a third cooling region which flow-connects the first cooling region and the second cooling region along the outlet chamber and is positioned at least in sections radially outside of the outlet chamber.

A free piston apparatus includes a piston receptacle in which a piston device having a piston is reciprocable along an axis. The piston receptacle includes or forms a chamber delimited by a wall arrangement forming an inlet opening and an outlet opening. A cooling device is arranged on the piston receptacle for cooling the wall arrangement. The cooling device includes or forms a cooling channel arranged radially outside on the wall arrangement. The cooling channel has first and second cooling regions axially on opposing sides of the outlet opening. The piston receptacle includes or forms an outlet chamber, arranged outside on the wall arrangement, for exhaust gas exiting via the outlet opening. The cooling channel has a third cooling region which flow-connects the first cooling region and the second cooling region along the outlet chamber and is positioned at least in sections radially outside of the outlet chamber.

A cooling apparatus includes: a radiator promoting heat radiation of cooling water of an engine; a first flow path circulating the cooling water discharged from the engine through the radiator to the engine; a second flow path circulating the cooling water discharged from the engine to the engine without through the radiator; a thermostat attached in a junction of the first and second flow paths, closing the first flow path when a temperature of the cooling water in the second flow path is lower than a threshold value, and opening the first flow path when the temperature of the cooling water in the second flow path is equal to or higher than the threshold value; and a third flow path communicating a part, of the first flow path between the engine and the radiator, with a part, of the first flow path between the radiator and the thermostat.

A fuel-based thermal management system may comprise a heat exchanger configured to thermally couple a fluid and a fuel. A controller may be configured to modulate a flow of the fluid to the heat exchanger. A tangible, non-transitory memory may be configured to communicate with the controller. The controller may determine a temperature of the fluid, estimate a dissolved oxygen concentration in the fuel using a first fuel temperature, a flight cycle time, and at least one of an altitude measurement or a ambient pressure measurement, and modulate the flow of the fluid to the heat exchanger based on the dissolved oxygen concentration.

A fuel-based thermal management system may comprise a heat exchanger configured to thermally couple a fluid and a fuel. A controller may be configured to modulate a flow of the fluid to the heat exchanger. A tangible, non-transitory memory may be configured to communicate with the controller. The controller may determine a temperature of the fluid, estimate a dissolved oxygen concentration in the fuel using a first fuel temperature, a flight cycle time, and at least one of an altitude measurement or a ambient pressure measurement, and modulate the flow of the fluid to the heat exchanger based on the dissolved oxygen concentration.

Methods and systems are provided for rapidly cooling an engine system of a vehicle at vehicle-off events. In one example, a method may include cooling the engine system via selecting whether to rotate a cooling fan in a first direction or a second direction based on an indication of whether temperature of the engine system decays at a faster rate under conditions where the cooling fan is rotated in the first direction as compared to the second direction, or vice versa. In this way, diagnostics that rely on static, low-noise conditions may be conducted for vehicle-off conditions that are not sufficiently long to allow for sufficient engine system cooling in a timeframe of the vehicle-off condition.

Methods and systems are provided for rapidly cooling an engine system of a vehicle at vehicle-off events. In one example, a method may include cooling the engine system via selecting whether to rotate a cooling fan in a first direction or a second direction based on an indication of whether temperature of the engine system decays at a faster rate under conditions where the cooling fan is rotated in the first direction as compared to the second direction, or vice versa. In this way, diagnostics that rely on static, low-noise conditions may be conducted for vehicle-off conditions that are not sufficiently long to allow for sufficient engine system cooling in a timeframe of the vehicle-off condition.