A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a turbine section including a fan drive turbine, a compressor section driven by the turbine section, a geared architecture driven by the fan drive turbine, and a fan driven by the fan drive turbine via the geared architecture. At least one stage of the turbine section includes an array of rotatable blades and an array of vanes. A ratio of the number of vanes to the number blades is greater than or equal to about 1.55. A mechanical tip rotational Mach number of the blades is configured to be greater than or equal to about 0.5 at an approach speed.

A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a propulsor section including a propulsor, a turbine section including a first turbine and a second turbine, a compressor section driven by the turbine section, the compressor section including a first compressor and a second compressor, and a geared architecture driven by the first turbine. The propulsor is driven by the first turbine via the geared architecture. At least one stage of the turbine section includes an array of rotatable blades and an array of vanes. A ratio of the number of vanes to the number blades is greater than or equal to 1.55. A mechanical tip rotational Mach number of the blades is configured to be greater than or equal to 0.5 at an approach speed.

An apparatus is provided for a gas turbine engine. This apparatus includes a gas turbine engine case extending axially along and circumferentially around an axis. The gas turbine engine case includes a sheet of metal wrapped multiple times around the axis to form a containment structure having a multi-layered configuration. The containment structure is configured to contain at least one of a blade or a blade fragment from a bladed rotor of the gas turbine engine within the at least one of a plurality of sections.

A gas turbine engine turbine has a high pressure turbine configured to rotate with a high pressure compressor as a high pressure spool in a first direction about a central axis and a low pressure turbine configured to rotate with a low pressure compressor as a low pressure spool in the first direction about the central axis. A power density is greater than or equal to about 1.5 and less than or equal to about 5.5 lbf/cubic inches. A fan is connected to the low pressure spool via a speed changing mechanism and rotates in the first direction.

The invention relates to a structural assembly for a gas turbine engine, which structural assembly comprises a fan and a forked fan shaft, which is coupled to the fan and comprises a radially outer fan shaft and a radially inner fan shaft being fixedly connected to the fan, and the predetermined breaking point being designed to break when a fan blade is lost. A contact mechanism is provided, which is activated by a decrease in the rotational speed of the fan shafts and which couples the radially inner fan shaft to the radially outer fan shaft when the rotational speed of the fan shafts falls below a predefined rotational speed after the predetermined breaking point has broken. After the fan shafts have been coupled by the contact mechanism, radially acting forces are transmitted from the radially inner fan shaft to the radially outer fan shaft.

A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a propulsor section including a propulsor, a turbine section including a first turbine and a second turbine, a compressor section driven by the turbine section, the compressor section including a first compressor and a second compressor, and a geared architecture driven by the first turbine. The propulsor is driven by the first turbine via the geared architecture. At least one stage of the turbine section includes an array of rotatable blades and an array of vanes. A ratio of the number of vanes to the number blades is greater than or equal to 1.55. A mechanical tip rotational Mach number of the blades is configured to be greater than or equal to 0.5 at an approach speed.

A turbofan gas turbine engine includes a core engine within a core nacelle, a fan nacelle at least partially surrounding the core nacelle to define a bypass flow path and a variable fan nozzle exit area for bypass flow, and a pylon variable area flow system which operates to effect the bypass flow. A method of operating a turbofan gas turbine engine is also disclosed.

An active device for attenuating the acoustic emissions of an aircraft turbojet engine includes circulation conduits for a pressurized air flow rate supplying rotary elements each having a pulsation system for the delivered air. The rotary elements are controlled in amplitude and phase and deliver, to outlet diffusers, a pulsed air flow rate with a pulsation at the frequency of the noise to be attenuated having an amplitude and a phase adjusted according to a local feedback law with microphones to attenuate the radiated acoustic power.

A gas turbine engine, has: a case extending circumferentially around a central axis of the gas turbine engine; a boss protruding from the case away from the central axis, the boss defining an internal passage; a tubular member received within the internal passage of the boss and secured to the boss; an annular gap extending all around the tubular member and located between the tubular member and the boss; and a fitting hydraulically connecting a fluid source to the tubular member, the fitting having a portion received within the tubular member and encircled by both of the annular gap and the tubular member, the fitting sealingly engaged to the tubular member.

A gas turbine engine, has: a case extending circumferentially around a central axis of the gas turbine engine; a boss protruding from the case away from the central axis, the boss defining an internal passage; a tubular member received within the internal passage of the boss and secured to the boss; an annular gap extending all around the tubular member and located between the tubular member and the boss; and a fitting hydraulically connecting a fluid source to the tubular member, the fitting having a portion received within the tubular member and encircled by both of the annular gap and the tubular member, the fitting sealingly engaged to the tubular member.