Abstract:
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.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. Provisional Application Ser. No. 61/775,100, entitled “Rotor Noise Suppression,” filed Mar. 8, 2013, which is incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    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 
       [0003]    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 
       [0004]    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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]    The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
           [0006]      FIG. 1  depicts an embodiment of an internal combustion engine operable to power an aircraft. 
           [0007]      FIG. 2  depicts an airfoil member in communication with a fluid source to reduce rotor noise. 
           [0008]      FIG. 3  depicts an embodiment of a rotor noise suppression system utilized in an open rotor configuration. 
       
    
    
     DETAILED DESCRIPTION 
       [0009]    For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates. 
         [0010]    With reference to  FIG. 1 , one embodiment is disclosed of an internal combustion engine  50  useful to provide a power to an aircraft  51  which can take the form of mechanical and/or electrical power to drive, for example, accessories associated with either or both of the engine  50  and aircraft  51 . Though the internal combustion engine  50  is depicted in the form of a gas turbine engine, the engine  50  can take a variety of other forms including, but not limited to, reciprocating engines and rotary engines. 
         [0011]    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. 
         [0012]    In the illustrated embodiment, the internal combustion engine  50  includes a compressor  52 , combustor  54 , and turbine  56  which together are used together to produce a useful power. Though the gas turbine engine  50  is disclosed as a single spool turbojet engine, in other embodiments the gas turbine engine  50  can be a multi spool engine. In any number of embodiments the gas turbine engine  50  can be an axial flow, centrifugal flow, or mixed flow engine. In some embodiments the gas turbine engine  50  can be an adaptive and/or variable cycle engine. 
         [0013]    With reference to  FIG. 2 , a rotatable airfoil member  120  is depicted and includes a leading edge  104 , a trailing edge  112 , and a mean camber line  102 . The rotatable airfoil member  120  is structured to be drivingly rotated about an axis such as an engine axis associated with the gas turbine engine  50 . In one form the rotatable airfoil member  120  is an open rotor structured to rotate about a centerline of the gas turbine engine. The airfoil member  120  includes at least one aperture  110  in flow communication with a fluid source  108 , and through which a fluid can be ejected that originates with the fluid source  108 . The fluid source  108  can be a fluid flow path within the gas turbine engine  50  that conveys products of combustion produced in the combustor  54  and that is ultimately exhausted from the gas turbine engine  50  through the turbine  56  and 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 combustor  54  that is being exhausted through the turbine  56 . The fluid source  108  can be a flow path through the turbine  56 , or a flow path located between the turbine  56  and a discharge opening through which an exhaust flow exits the gas turbine engine  50  and/or aircraft  51 . The fluid source  108  can pick up flow from any position within the turbine  56 , for example at an upstream, midstream, or downstream stage of the turbine  56 . In some forms the fluid source can pick up flow after a final stage of the turbine  56  and before the discharge opening. 
         [0014]    In the illustrated embodiment a plurality of the apertures  110  are disposed radially outwardly along the span of the airfoil member  120 . The aperture  110  can take any variety of forms and shapes such as round or oblong form, a singular slot or series of slots disposed along the airfoil member  120 , etc. Not all apertures associated with the airfoil member  120  need be the same. Some variation can be present in the apertures. For example, some apertures  110  located closest to a root of the airfoil member  120  can have different shapes than apertures  110  located closer to a tip of the airfoil member  120 . In short, the aperture  110  can take any form such that a fluid  114  received from the fluid source  108  can exit from the airfoil  120  through the aperture  110 . The aperture  110  can also be located in any variety of chord locations. For example, the aperture  110  can be located near the trailing edge  112  of the airfoil member  120 . In one form, the aperture  110  is located at an intersection of the mean camber line  102  and the trailing edge  112 . The aperture  110  can be flush with the airfoil  120  at a location where the fluid  114  exits the airfoil  120 . 
         [0015]    A flow channel  116  places the aperture  110  in flow communication with the fluid source  108 . The flow channel  116  extends within the airfoil  120  and can terminate at the aperture  110 . A plurality of flow channels  116  can extend from the fluid source  108  to the aperture  110 , or alternately a single flow channel  116  can split into a plurality of flow channels  116  to provide the fluid  114  to the aperture  110 . A flow regulator  122  can control a flow of the fluid  114  through the flow channel  116 . The flow regulator  122  can take the form of a valve  122  which can be a simple on/off valve, a variable flow valve, or any other valve  122  which can alter a flow of the fluid  114  through the flow channel  116 . 
         [0016]    Referring to  FIG. 3 , a portion of the exhaust gas  60  is utilized as the fluid  114 . An exhaust portion  304  is located between the turbine  56  of the gas turbine engine  50  and an exhaust exit  318 . An inlet  302  to a passage that conveys exhaust gas to the airfoil member  120  receives at least a portion of the exhaust gas  60  from the exhaust portion  304 , the exhaust gas  60  flowing through the flow channel  116  and emitting out of the aperture  110 , as has been previously described. There can be multiple inlets  302  to supply the exhaust gas  60  to the flow channel  116 . In a form of the gas turbine engine  50  which includes multiple turbine stages  56 , the inlet  302  can be located between turbine stages  56  and/or can be located downstream of the final turbine stage  56 . 
         [0017]    The airfoil member  120  is disposed upstream of an airfoil  314 , both of which are rotatable about an axis  62 . In one form the axis  62  is a centerline axis of the gas turbine engine  50 . The airfoil member  120  and the airfoil  314  can be open rotor blades  120 ,  314  which act upon a working fluid  316  and increase a velocity of the free stream  316 . In an open rotor architecture  306 , the airfoil member  120  and the airfoil  314  act upon the free stream  316  to provide a motive force for the aircraft  51 . Various configurations of open rotor concepts will be appreciated, one of which shows the airfoil members  120  and  314  positioned at an aft location relative to a nacelle  312  as depicted in the illustrated embodiment. The nacelle  312  in the illustrated embodiment includes an upstream inlet structured on a forward end to receive the working fluid  58 , and the exhaust exit  318  on an aft end of the nacelle  312 . The free stream  316  can 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 engine  50 . The exhaust gas  60  emitted from the airfoil  120  alters a velocity gradient of the working fluid  316  downstream of the airfoil  120  and upstream of the airfoil  314  in a manner such that a reduction in the amount of noise produced by airfoil  314  as it is rotated through the working fluid  316  can occur. The exhaust gas  60  emitted from the airfoil  120  reduces the impact of the blade wake on the airfoil  314 . In one embodiment both the airfoil member  120  and airfoil  314  can include the apertures  110  discussed above. 
         [0018]    The airfoil member  120  and the airfoil member  314  can be counter rotating relative to one another such that the airfoil member  120  can be rotated in a first direction  308  and the airfoil  314  can be rotated in a second direction  310 , the first direction  308  being opposite the second direction  310 . 
         [0019]    While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.