A system is provided for an aircraft propulsion system. This system includes an inlet lip, a bulkhead and a piccolo tube for a thermal anti-icing system. The inlet lip extends circumferentially about an axial centerline. The bulkhead extends circumferentially about the axial centerline. The bulkhead is configured with the inlet lip to form a cavity axially between the inlet lip and the bulkhead. The piccolo tube extends circumferentially about the axial centerline within the cavity. The piccolo tube is configured with an elliptical cross-sectional geometry.

A system is provided for an aircraft propulsion system. This system includes an inlet lip, a bulkhead and a piccolo tube for a thermal anti-icing system. The inlet lip extends circumferentially about an axial centerline. The bulkhead extends circumferentially about the axial centerline. The bulkhead is configured with the inlet lip to form a cavity axially between the inlet lip and the bulkhead. The piccolo tube extends circumferentially about the axial centerline within the cavity. The piccolo tube is configured with an elliptical cross-sectional geometry.

In one embodiment, a system includes an inlet grid configured to reduce distortion of an incoming airflow. The system may also include a vibration device coupled to the inlet grid and a controller communicatively coupled to the vibration device. The controller may transmit a vibration signal to the vibration device causing the vibration device to vibrate the inlet grid such that the inlet grid resonates at a natural frequency inducing a mode shape in the inlet grid. The mode shape may break up and prevent ice on the inlet grid.

In one embodiment, a system includes an inlet grid configured to reduce distortion of an incoming airflow. The system may also include a vibration device coupled to the inlet grid and a controller communicatively coupled to the vibration device. The controller may transmit a vibration signal to the vibration device causing the vibration device to vibrate the inlet grid such that the inlet grid resonates at a natural frequency inducing a mode shape in the inlet grid. The mode shape may break up and prevent ice on the inlet grid.

A system for operating a gas turbine engine to mitigate the risk of ice formation within the engine, the system including a controller arranged to control at least one operational parameter of the engine such that the engine operates in a safe zone; and, a processor configured to function as a determining module to make a comparison between values and determine whether the engine is operating within a safe zone based on at least a core pressure parameter relating to the pressure within the engine and a core temperature parameter relating to the temperature within the engine, wherein the safe zone is defined by the product (multiplied) of the core pressure parameter and core temperature parameter being above a safe threshold.

An anti-icing system of a nacelle inlet of an engine of an aircraft includes first and second direct acting valves and first and second control valve assemblies fluidly connected to the nacelle inlet. The first direct acting valve includes a first inlet, outlet, valve chamber, and piston. The first piston is positioned in the first direct acting valve. The first control valve assembly is fluidly connected to the first valve. The second direct acting valve includes a second inlet, outlet, valve chamber, and piston. The second piston is positioned in the second direct acting valve. The second direct acting valve is fluidly connected to the first direct acting valve in a series configuration. The second control valve assembly is fluidly connected to the second valve chamber.

A turbofan engine has a fan drivingly engaged by a shaft for rotation about a rotation axis and having: fan blades circumferentially distributed about the rotation axis and drivingly engaged by the shaft; an ice-accruing feature located on a surface of the fan exposed to an air flow flowing between the fan blades, the ice-accruing feature having a shape providing a non-axisymmetric ice accumulation on the fan to create a rotational imbalance; a balancing feature secured to the fan or to the shaft to counteract the ice-accruing feature such that the fan is rotationally balanced when the fan is free of ice, the balancing feature being located such as to be outside the air flow; an aircraft controller; and a sensor operatively connected to the fan and operable to send a signal to the aircraft controller, the signal indicative of the rotational imbalance caused by the ice-accruing feature.

A gas turbine engine comprises a fan mounted to rotate about a main longitudinal axis; an engine core, comprising in axial flow series a compressor, a combustor, and a turbine coupled to the compressor through a shaft; a reduction gearbox that receives an input from the shaft and outputs drive to the fan so as to drive the fan at a lower rotational speed than the shaft; wherein the compressor comprises a first stage at an inlet and a second stage, downstream of the first stage, comprising respectively a first rotor with a row of first blades and a second rotor with a row of second blades, the first and second blades comprising respective leading edges, trailing edges and tips, and wherein the ratio of a maximum leading edge radius of the first blades to a maximum leading edge radius of the second blades is greater than 2.8.

A turbo machine including a plenum is formed within a double wall structure including an opening configured to provide fluid communication of a first flow of fluid between the plenum through the double wall structure, and an outer wall forming a passage configured to receive a second flow of fluid separate from the first flow of fluid, wherein a flowpath structure is formed at least in part within an inner wall, the flowpath structure configured to receive a third flow of fluid therethrough, the third flow of fluid separate from the first flow of fluid, the flowpath structure comprising an exit opening configured to provide fluid communication from the flowpath structure to the flowpath.

A turbo machine including a plenum is formed within a double wall structure including an opening configured to provide fluid communication of a first flow of fluid between the plenum through the double wall structure, and an outer wall forming a passage configured to receive a second flow of fluid separate from the first flow of fluid, wherein a flowpath structure is formed at least in part within an inner wall, the flowpath structure configured to receive a third flow of fluid therethrough, the third flow of fluid separate from the first flow of fluid, the flowpath structure comprising an exit opening configured to provide fluid communication from the flowpath structure to the flowpath.