TECHNICAL FIELD

The application relates generally to gas turbine engines and, more particularly, to rotors of gas turbine engines.

BACKGROUND

Current fan noise control methods may be expensive and complex to design. These methods may include, for example, forward swept blade design, operating the engine at high bypass ratio, geared turbofan, scarfed inlet, trailing edge blowing or using a variable nozzle. Acoustic treatments for the fan and bypass stator vanes may also be used to reduce the noise. Changing the fan running line by using a variable nozzle may increase engine complexity, cost and weight. Other active methods that could be used to control noise, such as trailing edge blowing, involve drilling holes inside the fan blade for blowing flow.

SUMMARY

In one aspect, there is provided a gas turbine engine comprising: a rotor including: a hub; and a plurality of blades extending generally radially from the hub, each of the blades having an airfoil portion, the airfoil portion having a leading edge and a trailing edge defining a chordwise direction, and a root and a tip defining a spanwise direction, only a sub-set of the blades having a cutback at at least one of the trailing edge and the leading edge.

In another aspect, there is provided a method of assembling a rotor of a gas turbine engine, the method comprising: obtaining a pattern of disposition of blades about a hub, the pattern of disposition having at least a first and a second set of blades having shapes different from one another and positions relative to one another based on predetermined zones of asymmetrical shockwave distribution of the flow around the rotor, such that, when in operation, a flow around the rotor has a substantially symmetrical shockwave distribution; obtaining a first set of blades including at least one blade having a first shape as determined by the pattern; obtaining a second set of blades including at least one blade having a second shape different from the first shape as determined by the pattern; and assembling the first and second sets of blades onto the hub to replicate the pattern of disposition.

In a further aspect, a method of assembling a rotor of a gas turbine engine, the method comprising: obtaining a pattern of disposition of blades about a hub, the pattern of disposition having at least a first and a second set of blades having shapes different from one another such that, when in operation, a flow around the rotor has a substantially symmetrical shockwave distribution; obtaining a first set of blades including at least one blade having a first shape as determined by the pattern; obtaining a second set of blades including at least one blade having a second shape different from the first shape and designed based on predetermined zones of asymmetrical shockwave distribution of the flow around the rotor; and assembling the first and second sets of blades onto the hub to replicate the pattern of disposition.

