Tunable acoustic system
First Claim
1. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port by varying of one said length and said area of said port along a movable arcuate surface, wherein said adjustable port structure comprises a pair of arcuate surfaces, including a first arcuate surface movable toward and away from a second arcuate surface, and wherein said first and second arcuate surfaces have different radii of curvature.
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Accused Products
Abstract
An acoustic resonator (20) has a resonator cavity (22) with a resonator port (24) for communicating with an exhaust flow passage (26) conducting acoustic waves therethrough. Adjustable port structure varies acoustic impedance of the port by various combinations including translation to vary area along an arcuate surface, translation between discrete areas, translation to cumulatively open port area, multiple translation, multiple ports, rotational area change, and rotational length change. Adaptive control may be provided. A combined passive and active acoustic system may also be provided.
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Citations
29 Claims
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1. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port by varying of one said length and said area of said port along a movable arcuate surface, wherein said adjustable port structure comprises a pair of arcuate surfaces, including a first arcuate surface movable toward and away from a second arcuate surface, and wherein said first and second arcuate surfaces have different radii of curvature.
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2. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port by varying of one said length and said area of said port along a movable arcuate surface, wherein said adjustable port structure comprises a pair of arcuate surfaces, including a first arcuate surface movable toward and away form a second arcuate surface, and wherein said first arcuate surface is rotatable about a rotation axis parallel to said given direction to vary said area of said port.
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3. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port by varying of one said length and said area of said port along a movable arcuate surface, wherein said adjustable port structure comprises a pair of arcuate surfaces, including a first arcuate surface movable toward and away form a second arcuate surface, and wherein said first arcuate surface is rotatable about a rotation axis parallel to said given direction to vary said length of said port.
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4. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure comprising a movable plate having first and second cut-outs and varying acoustic impedance of said port by movement varying one of said length and said area of said port, wherein said adjustable port structure comprises an opening of given diameter between said exhaust flow passage and said cavity, and wherein said plate is movable relative to said opening to cover and uncover said opening, said first and second cut-outs being spaced along said plate by a distance greater than said given diameter, and wherein said first and second cut-outs have different areas.
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5. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure comprising a movable plate having a cut-out, and comprising first and second openings communicating between said exhaust flow passage and said cavity and spaced by a distance greater than the transverse dimension of said cut-out in said plate, said plate being movable relative to said openings to cover and uncover same, including to a position with said cut-out between said first and second openings and said plate covering and closing said first and second openings, wherein said first and second openings have different areas.
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6. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic wave therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure comprising a movable plate having a cut-out, and comprising first and second openings communicating between said exhaust flow passage and said cavity and spaced by a distance greater than the transverse dimension of said cut-out in said plate, said plate being movable relative to said openings to cover and uncover same, including to a position with said cut-out between said first and second openings and said plate covering and closing said first and second openings, wherein said first and second openings have different shapes.
- 7. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure comprising a plate rotational about a rotation axis parallel to said given direction and having a cut-out movable along an arc upon rotation of said plate and varying acoustic impedance of said port by varying one of said length and said area of said port.
- 11. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure comprising a first surface movable by rotation about a rotation axis parallel to said given direction to a first position providing minimum acoustic impedance of said port, and movable by rotation about said rotation axis to a second position providing maximum acoustic impedance of said port.
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17. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port, said adjustable port structure comprising first and second members movable relative to each other, at least one of said members having a plurality of cut-outs covered and uncovered by the other member during said relative movement, wherein a first of said members is rotatable about a rotation axis parallel to said given direction to vary said area of said port.
- 18. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, adjustable port structure varying acoustic impedance of said port between said exhaust flow passage and said cavity by varying the length of said port and comprising a rotary member rotatable about a rotation axis parallel to said given direction, and wherein rotation of said rotary member about said rotation axis changes said length of said port.
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27. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, an adaptive controller driving adjustable port structure varying acoustic impedance of said port by varying one of said length and said area of said port, said exhaust flow passage having an input receiving an input acoustic wave, and an output outputting an output acoustic wave, said controller comprising an adaptive filter model having a model input from a reference signal correlated to said input acoustic wave, a model output outputting a correction signal to said adjustable port structure, and an error input receiving an error signal from an error transducer sensing said output acoustic wave, wherein said adjustable port structure comprises a plate rotational about a rotation axis parallel to said given direction and having a cut-out movable along an arc upon rotation of said plate and varying acoustic impedance of said port by varying one of said length and said area of said port.
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28. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, an adaptive controller driving adjustable port structure varying acoustic impedance of said port by varying one of said length and said area of said port, said exhaust flow passage having an input receiving an input acoustic wave, and an output outputting an output acoustic wave, said controller comprising an adaptive filter model having a model input from a reference signal correlated to said input acoustic wave, a model output outputting a correction signal to said adjustable port structure, and an error input receiving an error signal from an error transducer sensing said output acoustic wave, wherein said adjustable port structure comprises a first surface movable by rotation about a rotation axis parallel to said given direction to a first position providing minimum acoustic impedance of said port, and movable by rotation about said rotation axis to a second position providing maximum acoustic impedance of said port.
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29. An acoustic resonator comprising a resonator cavity having a resonator port for communicating with an exhaust flow passage conducting acoustic waves therethrough, said resonator port defining an acoustic propagation path along a given direction therethrough from said exhaust flow passage into said cavity, said port having a length extending parallel to said given direction, said port having an area extending along a plane transverse to said given direction, an adaptive controller driving adjustable port structure varying acoustic impedance of said port by varying one of said length and said area of said port, said exhaust flow passage having an input receiving an input acoustic wave, and an output outputting an output acoustic wave, said controller comprising an adaptive filter model having a model input from a reference signal correlated to said input acoustic wave, a model output outputting a correction signal to said adjustable port structure, and an error input receiving an error signal from an error transducer sensing said output acoustic wave, wherein said adjustable port structure varies acoustic impedance of said port between said exhaust flow passage and said cavity by varying the length of said port.
Specification