Abstract: Disclosed is an electrically driven ducted fan engine, comprising a housing with an inner housing wall, defining a substantially cylindrical inner space and a longitudinal axis, an inlet opening, a rotor with a multitude of rotor blades positioned in the inner space of the housing downstream of the inlet opening, a stator assembly with a multitude of guide vanes extending from a radially central region of the inner space to the inner wall of the housing, and an exhaust opening provided in the housing downstream of the stator assembly, an interstage region defined between the rotor and the stator assembly, a guide vane region defined in which guide vanes extend to the inner wall of the housing and an exhaust section, wherein in at least one of the interstage region, the guide vane region and the exhaust region, acoustic liners are provided to the housing.

Abstract: The dual resonator chamber with variable volume includes first and second housings. The second housing is slidably mounted within the first housing such that a second inner neck portion of the second housing is slidably mounted about the first inner neck portion of the first housing and forms a fluid-tight seal therewith. A sliding wall is slidably mounted within the second housing, dividing the interior thereof into upper and lower resonator chambers. At least one first actuator selectively adjusts the height of the sliding wall with respect to the second lower end of the second housing to selectively adjust volumes of the upper and lower resonator chambers. At least one second actuator selectively adjusts the height of the second housing with respect to the first housing to selectively adjust the neck length of the lower resonator chamber.

Abstract: The dual resonator chamber with variable volume includes first and second housings. The second housing is slidably mounted within the first housing such that a second inner neck portion of the second housing is slidably mounted about the first inner neck portion of the first housing and forms a fluid-tight seal therewith. A sliding wall is slidably mounted within the second housing, dividing the interior thereof into upper and lower resonator chambers. At least one first actutator selectively adjusts the height of the sliding wall with respect to the second lower end of the second housing to selectively adjust volumes of the upper and lower resonator chambers. At least one second actuator selectively adjusts the height of the second housing with respect to the first housing to selectively adjust the neck length of the lower resonator chamber.