An acoustic panel includes a first skin, a second skin and a cellular core vertically between and connected to the first skin and the second skin. The cellular core includes a plurality of cavities, a plurality of sidewalls and a plurality of septums. Each of the plurality of cavities extends vertically through the cellular core between the first skin and the second skin. Each of the plurality of cavities extends laterally within the cellular core between a respective laterally adjacent pair of the plurality of sidewalls. Each of the plurality of septums vertically divides a respective one of the plurality of cavities into a set of fluidly coupled sub-cavities. A set of the plurality of septums is formed by a ply of folded material. Each of the set of the plurality of septums have a four-sided polygonal shape when viewed in a plane that is parallel to the first skin.

An acoustic core includes an array of resonant cells. The array may include a plurality of coupled resonant cells respectively defining an antecedent resonant space and a subsequent resonant space, with at least one cell wall having one or more wall-apertures defining a pathway between the antecedent resonant space and the subsequent resonant space. The array may include a plurality of high-frequency resonant cells respectively defining a high-frequency resonant space and being matched with respective ones of the plurality of coupled resonant cells. A cross-sectional dimension of the one or more wall-apertures defining the pathway between the antecedent resonant space and the subsequent resonant space may be less than a cross-sectional dimension of the antecedent resonant space and/or a cross-sectional dimension of the subsequent resonant space. The array may include a plurality of partitioned resonant cells that have a partition integrally formed with at least one of a corresponding one or more cell walls and transecting the corresponding resonant space with at least one surface of the partition having an interface angle that is oblique or perpendicular relative to a plane parallel to a top face and/or a bottom face of the array of resonant cells.

A rotor blade of a wind turbine with a particle damping device having at least one cavity (3) with inner walls (4) delimiting an interior and with a medium arranged in the interior so as to be movable with respect to the inner walls (4). Additionally, a rotor blade is provided with a vibration-damping mechanism, and a method for manufacture of such a rotor blade.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan including a circumferential array of fan blades, a low pressure compressor section including a low pressure compressor section inlet with a low pressure compressor section inlet annulus area, and a fan duct annulus area outboard of the low pressure compressor section inlet, and a fan drive turbine section. The fan drive turbine section includes a maximum gas path radius and the fan blades include a maximum radius, and a ratio of the maximum gas path radius to the maximum radius of the fan blades is equal to or greater than 0.35, and is less than 0.55.

A turbofan engine has an engine case and a gaspath through the engine case. A fan has a circumferential array of fan blades. The engine further has a compressor, a combustor, a gas generating turbine, and a low pressure turbine section. A speed reduction mechanism couples the low pressure turbine section to the fan. A bypass area ratio is greater than about 6.0. The low pressure turbine section airfoil count to bypass area ratio is below about 170.

A self-excited wind power system with at least one self-excited panel, each arranged to create periodic motion in response to wind velocity, and a support tower. The self-excited panel is segmented, with at least three segments: a first segment forming a master segment, a second segment, and a third segment defining a tail segment. The first segment of the self-excited panel has a first length and a first height, the second segment has a second length half the length of the first segment and a second height one-third the height of the first segment, and the third segment has a third length half the length of the first segment and a third height one-third the height of the first segment. Furthermore, the second and third segments are connected to the proximal and distal ends of the first segment via a bearing mechanism.

A gas turbine engine according to an example of the present disclosure includes, among other things, a propulsor including a circumferential array of blades, a low pressure compressor section including a low pressure compressor section inlet with a low pressure compressor section inlet annulus area and a low pressure turbine section. The low pressure turbine section includes a maximum gas path radius, the blades include a maximum radius, and a ratio of the maximum gas path radius to the maximum radius of the blades is equal to or greater than 0.35, and is less than 0.55.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan including a circumferential array of fan blades, a compressor in fluid communication with the fan, the compressor including a first compressor section and a second compressor, the second compressor section including a second compressor section inlet with a second compressor section inlet annulus area, a fan duct including a fan duct annulus area outboard of the second compressor section inlet, a shaft assembly having a first portion and a second portion, a turbine in fluid communication with the combustor, the turbine having a first turbine section coupled to the first portion of the shaft assembly to drive the first compressor section, and a second turbine section coupled to the second portion of the shaft assembly to drive the fan, an epicyclic transmission coupled to the fan and rotatable by the second turbine section through the second portion of the shaft assembly to allow the second turbine to turn faster than the fan, wherein the second turbine section includes a maximum gas path radius and the fan blades include a maximum radius, and a ratio of the maximum gas path radius to the maximum radius of the fan blades is less than 0.6.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan including a circumferential array of fan blades, a compressor in fluid communication with the fan, the compressor including a low pressure compressor section and a high pressure compressor section, the low pressure compressor section including a low pressure compressor section inlet with a low pressure compressor section inlet annulus area, a fan duct including a fan duct annulus area outboard of the a low pressure compressor section inlet, a turbine in fluid communication with the combustor, the turbine having a high pressure turbine section and a low pressure turbine that drives the fan, a speed reduction mechanism coupled to the fan and rotatable by the low pressure turbine section to allow the low pressure turbine section to turn faster than the fan, wherein the low pressure turbine section includes a maximum gas path radius and the fan blades include a maximum radius, and a ratio of the maximum gas path radius to the maximum radius of the fan blades is between 0.50 and 0.55, or is greater than 0.55 and less than or equal to 0.65.

A turbofan engine according to an example of the present disclosure includes, among other things, a fan including an array of fan blades rotatable about an engine axis, a compressor including a high pressure compressor section and a low pressure compressor section, the low pressure compressor section including a low pressure compressor section inlet with a low pressure compressor inlet annulus area, a fan duct including a fan duct annulus area outboard of the low pressure compressor section inlet, and a turbine having a high pressure turbine section and a low pressure turbine section driving the fan through a speed reduction mechanism, wherein the low pressure turbine section defines a maximum gas path radius and the fan blades define a maximum radius, and a ratio of the maximum gas path radius to the maximum radius of the fan blades is less than 0.6.