A fan blade is provided and comprises a leading edge, an attachment root extending aft of the leading edge, and a trench formed in a surface of the attachment root. An attachment root is also provided. The attachment root comprises a leading edge, a dovetail extending aft of the leading edge, and a trench formed in a surface of the dovetail. A gas turbine engine is also provided. The gas turbine engine comprises a compressor section configured to rotate about an axis, a combustor aft of the compressor section, and a turbine section aft of the compressor section and configured to rotate about the axis. A fan may be disposed forward of the turbine section and include a blade. The blade may have a trench formed in an attachment root.

A centrifugal impeller having an axis of rotation extending from front to rear, and including a body extending around the axis of rotation, the body having a front portion and a rear portion of larger section than the front portion, the impeller also have blades projecting from a front face of the body, the body presenting a setback in its front face between two consecutive blades, which setback is situated at a circumferential distance from the two blades.

A dual motor system includes a first motor providing a lower speed range and a second motor providing a higher speed range, wherein the motors are coaxially arranged and aligned on and drive a common shaft, and a motor control system controlling the speed of the first motor and engaging the second motor as needed. The first motor is a variable speed motor providing a lower two-thirds of a full speed range, and the second motor is an induction motor providing the upper one-third in the form of one or more discrete fixed speeds. The system may include a transformer including a first winding tap which provides a first higher speed, and a second winding tap which provides a second higher speed. The system may also include a flow control system for automatically controlling the speed of the motors for particular applications, such as flow control in a pool.

A gas turbine engine rotor disk has a single-piece hub with a radially-outer surface, and with an annular cavity inside the single-piece hub. The annular cavity is defined by a radially-elongated cross-sectional profile revolved at least partly about the axis of rotation. Blades extend outwardly from the radially-outer surface.

A fan blade is provided and comprises a leading edge, an attachment root extending aft of the leading edge, and a trench formed in a surface of the attachment root. An attachment root is also provided. The attachment root comprises a leading edge, a dovetail extending aft of the leading edge, and a trench formed in a surface of the dovetail. A gas turbine engine is also provided. The gas turbine engine comprises a compressor section configured to rotate about an axis, a combustor aft of the compressor section, and a turbine section aft of the compressor section and configured to rotate about the axis. A fan may be disposed forward of the turbine section and include a blade. The blade may have a trench formed in an attachment root.

Mistuned bladed rotors and associated manufacturing methods are disclosed. An exemplary method includes forming two or more blades of the bladed rotor where the two or more blades have substantially identical external aerodynamic surfaces and have different internal configurations causing the two or more blades to have different natural frequencies.

A cooling tower fan hub having a ring and a disc in which in which hollows and recesses are opened in the ring and/or in the disc in order to decrease fan natural frequencies and avoid excitation by the several kind of loads that affect a fan during operation. The number, size and shape of the hollows can be adjusted to tune the fan natural frequencies around the original value.

A fan blade is provided and comprises a leading edge, an attachment root extending aft of the leading edge, and a trench formed in a surface of the attachment root. An attachment root is also provided. The attachment root comprises a leading edge, a dovetail extending aft of the leading edge, and a trench formed in a surface of the dovetail. A gas turbine engine is also provided. The gas turbine engine comprises a compressor section configured to rotate about an axis, a combustor aft of the compressor section, and a turbine section aft of the compressor section and configured to rotate about the axis. A fan may be disposed forward of the turbine section and include a blade. The blade may have a trench formed in an attachment root.

A method of producing a gas turbine engine fan blade having a geometric configuration is provided. The method includes: plastically deforming an initial substrate comprised of a first metallic material into a formed substrate; depositing a second metallic material onto the formed substrate using an additive manufacturing process to produce a blade blank, which depositing includes: additively depositing second metallic material to at least one of the first face surface or the second face surface of the formed substrate adjacent the first end surface, to form a root portion; additively depositing second metallic material to at least one of the first face surface or the second face surface of the formed substrate between the root portion and the second end surface to form an airfoil portion; and shaping the blade blank into the geometric configuration.

In a turbine rotor blade assembly 1 of the present invention, each turbine rotor blade 10 includes a platform 11 having a blade root 12 fixed to a turbine disk 30, a profile 13 rising from the platform 11, and a shroud 14 provided at a top end of the profile 13. The shroud 14 of the present invention includes a first contact end part 15 that comes into contact with an adjacent shroud adjacent to one end side in a circumferential direction, a second contact end part 16 that comes into contact with an another adjacent shroud adjacent to the other end side in the circumferential direction, and a main body part disposed between the first and second contact end parts 15 and 16. One or both of the first and second contact end parts 15 and 16 are lower in rigidity than the main body part.