Rotor noise suppression

An apparatus is disclosed that includes a gas turbine engine including a first rotor blade axially adjacent a second rotor blade and an aperture formed in one of the first rotor blade and the second rotor blade and structured to emit a fluid therefrom. A fluid source is in flow communication with the aperture and configured to flow the fluid through the aperture.

FIELD OF THE INVENTION

The present invention generally relates to reduction in noise of rotor blades, and more particularly, but not exclusively, to the noise reduction of open rotor blades driven by gas turbine engines.

BACKGROUND

Noise suppression techniques useful with bladed rotors that are driven by internal combustion engines, such as a gas turbine engine, remains an area of interest. Some existing systems have various shortcomings relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology.

SUMMARY

One embodiment of the present invention is a unique rotor noise suppression system for use with a gas turbine engine. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for rotor noise suppression. Further embodiments, forms, features, aspects, benefits, and advantages of the present application shall become apparent from the description and figures provided herewith.

DETAILED DESCRIPTION

With reference toFIG. 1, one embodiment is disclosed of an internal combustion engine50useful to provide a power to an aircraft51which can take the form of mechanical and/or electrical power to drive, for example, accessories associated with either or both of the engine50and aircraft51. Though the internal combustion engine50is depicted in the form of a gas turbine engine, the engine50can take a variety of other forms including, but not limited to, reciprocating engines and rotary engines.

As used herein, the term “aircraft” includes, but is not limited to, helicopters, airplanes, unmanned space vehicles, fixed wing vehicles, variable wing vehicles, rotary wing vehicles, unmanned combat aerial vehicles, tailless aircraft, hover crafts, and other airborne and/or extraterrestrial (spacecraft) vehicles. Further, the present inventions are contemplated for utilization in other applications that may not be coupled with an aircraft such as, for example, industrial applications, power generation, pumping sets, naval propulsion, weapon systems, security systems, perimeter defense/security systems, and the like known to one of ordinary skill in the art.

In the illustrated embodiment, the internal combustion engine50includes a compressor52, combustor54, and turbine56which together are used together to produce a useful power. Though the gas turbine engine50is disclosed as a single spool turbojet engine, in other embodiments the gas turbine engine50can be a multi spool engine. In any number of embodiments the gas turbine engine50can be an axial flow, centrifugal flow, or mixed flow engine. In some embodiments the gas turbine engine50can be an adaptive and/or variable cycle engine.

With reference toFIG. 2, a rotatable airfoil member120is depicted and includes a leading edge104, a trailing edge112, and a mean camber line102. The rotatable airfoil member120is structured to be drivingly rotated about an axis such as an engine axis associated with the gas turbine engine50. In one form the rotatable airfoil member120is an open rotor structured to rotate about a centerline of the gas turbine engine. The airfoil member120includes at least one aperture110in flow communication with a fluid source108, and through which a fluid can be ejected that originates with the fluid source108. The fluid source108can be a fluid flow path within the gas turbine engine50that conveys products of combustion produced in the combustor54and that is ultimately exhausted from the gas turbine engine50through the turbine56and out a discharge opening. As used herein, therefore, the term “exhaust flow” includes flow at the discharge opening, as well as flow produced from the combustor54that is being exhausted through the turbine56. The fluid source108can be a flow path through the turbine56, or a flow path located between the turbine56and a discharge opening through which an exhaust flow exits the gas turbine engine50and/or aircraft51. The fluid source108can pick up flow from any position within the turbine56, for example at an upstream, midstream, or downstream stage of the turbine56. In some forms the fluid source can pick up flow after a final stage of the turbine56and before the discharge opening.

In the illustrated embodiment a plurality of the apertures110are disposed radially outwardly along the span of the airfoil member120. The aperture110can take any variety of forms and shapes such as round or oblong form, a singular slot or series of slots disposed along the airfoil member120, etc. Not all apertures associated with the airfoil member120need be the same. Some variation can be present in the apertures. For example, some apertures110located closest to a root of the airfoil member120can have different shapes than apertures110located closer to a tip of the airfoil member120. In short, the aperture110can take any form such that a fluid114received from the fluid source108can exit from the airfoil120through the aperture110. The aperture110can also be located in any variety of chord locations. For example, the aperture110can be located near the trailing edge112of the airfoil member120. In one form, the aperture110is located at an intersection of the mean camber line102and the trailing edge112. The aperture110can be flush with the airfoil120at a location where the fluid114exits the airfoil120.

A flow channel116places the aperture110in flow communication with the fluid source108. The flow channel116extends within the airfoil120and can terminate at the aperture110. A plurality of flow channels116can extend from the fluid source108to the aperture110, or alternately a single flow channel116can split into a plurality of flow channels116to provide the fluid114to the aperture110. A flow regulator122can control a flow of the fluid114through the flow channel116. The flow regulator122can take the form of a valve122which can be a simple on/off valve, a variable flow valve, or any other valve122which can alter a flow of the fluid114through the flow channel116.

Referring toFIG. 3, a portion of the exhaust gas60is utilized as the fluid114. An exhaust portion304is located between the turbine56of the gas turbine engine50and an exhaust exit318. An inlet302to a passage that conveys exhaust gas to the airfoil member120receives at least a portion of the exhaust gas60from the exhaust portion304, the exhaust gas60flowing through the flow channel116and emitting out of the aperture110, as has been previously described. There can be multiple inlets302to supply the exhaust gas60to the flow channel116. In a form of the gas turbine engine50which includes multiple turbine stages56, the inlet302can be located between turbine stages56and/or can be located downstream of the final turbine stage56.

The airfoil member120is disposed upstream of an airfoil314, both of which are rotatable about an axis62. In one form the axis62is a centerline axis of the gas turbine engine50. The airfoil member120and the airfoil314can be open rotor blades120,314which act upon a working fluid316and increase a velocity of the free stream316. In an open rotor architecture306, the airfoil member120and the airfoil314act upon the free stream316to provide a motive force for the aircraft51. Various configurations of open rotor concepts will be appreciated, one of which shows the airfoil members120and314positioned at an aft location relative to a nacelle312as depicted in the illustrated embodiment. The nacelle312in the illustrated embodiment includes an upstream inlet structured on a forward end to receive the working fluid58, and the exhaust exit318on an aft end of the nacelle312. The free stream316can be defined as an airflow which is not directly acted upon or directly affected by turbomachinery within the casing (not shown) of the gas turbine engine50. The exhaust gas60emitted from the airfoil120alters a velocity gradient of the working fluid316downstream of the airfoil120and upstream of the airfoil314in a manner such that a reduction in the amount of noise produced by airfoil314as it is rotated through the working fluid316can occur. The exhaust gas60emitted from the airfoil120reduces the impact of the blade wake on the airfoil314. In one embodiment both the airfoil member120and airfoil314can include the apertures110discussed above.

The airfoil member120and the airfoil member314can be counter rotating relative to one another such that the airfoil member120can be rotated in a first direction308and the airfoil314can be rotated in a second direction310, the first direction308being opposite the second direction310.