A turbofan gas turbine engine includes, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, and a turbine module. The fan assembly includes fan blades defining a corresponding fan area (A.sub.FAN). The heat exchanger module is in fluid communication with the fan assembly by an inlet duct, and includes radially-extending vanes arranged in a circumferential array with at least one vane including a heat transfer element for heat transfer from a first fluid contained within each element to an airflow passing over a surface of each heat transfer element before entering the fan assembly inlet. Each heat transfer element extends axially along the corresponding vane, with a swept heat transfer element area (A.sub.HTE) being the wetted surface area of all heat transfer elements in contact with the airflow. A Fan to Element Area parameter F.sub.EA of A.sub.HTE/A.sub.FAN lies in the range of 47 to 132.

A turbofan gas turbine engine includes, in axial flow sequence, a heat exchanger module, a fan assembly, a compressor module, and a turbine module. The fan assembly includes fan blades defining a corresponding fan area (A.sub.FAN). The heat exchanger module is in fluid communication with the fan assembly by an inlet duct, and includes radially-extending vanes arranged in a circumferential array with at least one vane including a heat transfer element for heat transfer from a first fluid contained within each element to an airflow passing over a surface of each heat transfer element before entering the fan assembly inlet. Each heat transfer element extends axially along the corresponding vane, with a swept heat transfer element area (A.sub.HTE) being the wetted surface area of all heat transfer elements in contact with the airflow. A Fan to Element Area parameter F.sub.EA of A.sub.HTE/A.sub.FAN lies in the range of 47 to 132.

An aircraft engine comprising a fan, the fan having a diameter D and including a plurality of fan blades, the fan blades having a sweep metric S.sub.tip, each fan blade having a leading edge, and a forward-most portion on the leading edge of each fan blade being in a first reference plane. The aircraft engine further comprises a nacelle, comprising an intake portion forward of the fan, a forward edge on the intake portion being in a second reference plane, wherein the intake portion has a length L measured along an axis of the aircraft engine between the first reference plane and the second reference plane, the aircraft engine having a cruise design point condition M.sub.rel, wherein M.sub.rel is between 0.4 and 0.93, L/D is between 0.2 and 0.45 and S.sub.tip is from −1 to 0.1.

An aircraft engine comprising a fan, the fan having a diameter D and including a plurality of fan blades, the fan blades having a sweep metric S.sub.tip, each fan blade having a leading edge, and a forward-most portion on the leading edge of each fan blade being in a first reference plane. The aircraft engine further comprises a nacelle, comprising an intake portion forward of the fan, a forward edge on the intake portion being in a second reference plane, wherein the intake portion has a length L measured along an axis of the aircraft engine between the first reference plane and the second reference plane, the aircraft engine having a cruise design point condition M.sub.rel, wherein M.sub.rel is between 0.4 and 0.93, L/D is between 0.2 and 0.45 and S.sub.tip is from −1 to 0.1.

A turbofan engine has a fan portion in fluid communication with a core stream and a bypass stream of air separated by splitters disposed both upstream and downstream of the fan portion. A blade splitter (shroud) on the fan partially spans the fan blade thus separating the core and bypass streams downstream while leaving a gap upstream for communication between the flows. The communication gap expands the operational range of the fan over fans without the communication gap.

A turbofan engine has a fan portion in fluid communication with a core stream and a bypass stream of air separated by splitters disposed both upstream and downstream of the fan portion. A blade splitter (shroud) on the fan partially spans the fan blade thus separating the core and bypass streams downstream while leaving a gap upstream for communication between the flows. The communication gap expands the operational range of the fan over fans without the communication gap.

An air inlet into a nacelle of an aircraft turbojet engine having a de-icing device and extends along an axis X, an air stream flowing in the air inlet from upstream to downstream, the inlet comprising an inner wall and an outer wall which are connected by a leading edge, the inner wall having a plurality of air delivery lines, each air delivery line having a plurality of through-holes designed to blow elementary streams from the hot air source in order to de-ice said inner wall, the air delivery lines being parallel to one another in a cylindrical projection plane, each air delivery line having a depth P3 defined along the axis X as well as a length L3 defined along the axis Y in the cylindrical projection plane, two adjacent air delivery lines being spaced apart by a distance D3, each position along the axis Y with no more than one through-hole, the ratio of the distances L3/D3 being between 0.8 and 1.

An air inlet into a nacelle of an aircraft turbojet engine having a de-icing device and extends along an axis X, an air stream flowing in the air inlet from upstream to downstream, the inlet comprising an inner wall and an outer wall which are connected by a leading edge, the inner wall having a plurality of air delivery lines, each air delivery line having a plurality of through-holes designed to blow elementary streams from the hot air source in order to de-ice said inner wall, the air delivery lines being parallel to one another in a cylindrical projection plane, each air delivery line having a depth P3 defined along the axis X as well as a length L3 defined along the axis Y in the cylindrical projection plane, two adjacent air delivery lines being spaced apart by a distance D3, each position along the axis Y with no more than one through-hole, the ratio of the distances L3/D3 being between 0.8 and 1.

A secondary air system (SAS) of an aircraft engine that produces secondary airflow from a source of secondary air includes a hollow strut and one or more SAS feed pipes upstream thereof. The hollow strut extends radially through the main gas path of the engine and defines therein a strut conduit extending between a strut inlet and a strut outlet at opposite ends of the hollow strut. The strut outlet is in fluid flow communication with a buffer cavity for feeding the secondary airflow to the engine core. The SAS feed pipe includes an inlet receiving the secondary airflow from the source of secondary air, and an outlet in fluid flow communication with the strut inlet to feed the secondary airflow into the strut conduit. The SAS feed pipe has a sonic orifice therein, between the inlet and the outlet thereof.

A secondary air system (SAS) of an aircraft engine that produces secondary airflow from a source of secondary air includes a hollow strut and one or more SAS feed pipes upstream thereof. The hollow strut extends radially through the main gas path of the engine and defines therein a strut conduit extending between a strut inlet and a strut outlet at opposite ends of the hollow strut. The strut outlet is in fluid flow communication with a buffer cavity for feeding the secondary airflow to the engine core. The SAS feed pipe includes an inlet receiving the secondary airflow from the source of secondary air, and an outlet in fluid flow communication with the strut inlet to feed the secondary airflow into the strut conduit. The SAS feed pipe has a sonic orifice therein, between the inlet and the outlet thereof.