Abstract: Various embodiments of a vortex thruster system is described herein that is configured to create at least three discrete thrust levels. In some embodiments, the vortex thruster system is configured to decompose a monopropellant and deliver the decomposed monopropellant into a vortex combustion chamber for generating various thrust levels. In some embodiments, the vortex thruster system includes a secondary propellant valve configured to deliver a secondary propellant into the vortex combustion chamber containing decomposed monopropellant to create a high thrust level. Related systems, methods, and articles of manufacture are also described.

Abstract: A swirl preburner that includes a first core defining a first swirl chamber having a first swirl chamber first end and a first swirl chamber second end, the first swirl chamber comprising a first diameter at the first swirl chamber first end and a second smaller diameter at the first swirl chamber second end that is smaller than the first diameter; and a second core defining a second swirl chamber having a second swirl chamber first end and a second swirl chamber second end, the second swirl chamber comprising a third diameter at the second swirl chamber first end and a fourth smaller diameter at the second swirl chamber second end that is smaller than the third diameter, the first diameter being smaller than the third diameter and larger than the fourth smaller diameter.

Abstract: Various embodiments of a vortex thruster system is described herein that is configured to create at least three discrete thrust levels. In some embodiments, the vortex thruster system is configured to decompose a monopropellant and deliver the decomposed monopropellant into a vortex combustion chamber for generating various thrust levels. In some embodiments, the vortex thruster system includes a secondary propellant valve configured to deliver a secondary propellant into the vortex combustion chamber containing decomposed monopropellant to create a high thrust level. Related systems, methods, and articles of manufacture are also described.

Abstract: A filter muffler includes a front element, a rear element, and a plurality of damping elements arranged between the front element and the rear element, where the damping elements are arranged radially around a central axis of the filter muffler such that a flow channel is formed between adjacent damping elements, where respective outflow-side ends of the damping elements have a diffuser element which has an outflow-side tapering, and where an angle ? between two opposite sides of the diffuser element is selected from a range of 1°???8°.

Abstract: An internal structure of a primary exhaust duct of a turbomachine, which has a primary wall allowing air to pass through orifices and forming an internal surface of the primary exhaust duct, an interior skin arranged inside the primary wall, and at least one separator of which a first edge region is attached to the interior skin and which has two geometries. A change from the first geometry to the second takes place when the temperature of the separator exceeds a first temperature, and the change from the second to the first takes place when the temperature of the separator drops below a second temperature. The coefficient of expansion of the separator is greater than that of the interior skin. The variation in the geometry of the separators depending on the temperature of the engine eases assembly at ambient temperature due to the compression of the separators.

Abstract: A filter muffler includes a front element, a rear element, and a plurality of damping elements arranged between the front element and the rear element, where the damping elements are arranged radially around a central axis of the filter muffler such that a flow channel is formed between adjacent damping elements, where respective outflow-side ends of the damping elements have a diffuser element which has an outflow-side tapering, and where an angle ? between two opposite sides of the diffuser element is selected from a range of 1°???8°.

Abstract: An aircraft control system and method to optimize aircraft control based on noise abatement volumes. A noise abatement component computes optimal flight and engine control based on a line-of-sight distance to minimize direct operating cost (DOC) while complying with community noise regulations.

Abstract: An apparatus and method for cooling a fluid within a turbine engine. A fan casing assembly for the turbine engine can include an annular fan casing with a peripheral wall having a flow path defined through the casing. A fan casing cooler includes a body to confront the peripheral wall with at least one conduit configured to carry a flow of heated fluid to convectively cool the heated fluid with a flow of air through the flow path.

Abstract: A non-metallic tailcone in a tip turbine engine includes a tapered wall structure disposed about a central axis. The non-metallic tailcone is fastened to a structural frame in the aft portion of the tip turbine engine. The tip turbine engine produces a first temperature gas stream from a first output source and a second temperature gas stream from a second output source. The second temperature gas stream is a lower temperature than the first temperature gas stream. The second temperature gas stream is discharged at an inner diameter of the tip turbine engine over an outer surface of the tailcone. Discharging the cooler second temperature gas stream at the inner diameter allows a non-metallic to be used to form the tailcone.

Abstract: Methods and systems are provided for adjusting flow of exhaust gas from downstream of an exhaust turbine outlet to an exhaust gas aftertreatment device inlet via a compact turbine outlet cone with adjustable swirl vanes. Exhaust flow reaching the exhaust gas aftertreatment device is adjusted based on a desired exhaust gas temperature and exhaust gas flow rate at the aftertreatment device. During cold start conditions, the swirl vanes may be closed to concentrate exhaust gas flowing towards a portion of the aftertreatment device while after attainment of aftertreatment device light-off temperature, the position of the swirl vanes may be adjusted to introduce turbulence and homogeneity to exhaust flow reaching the exhaust aftertreatment device.

Abstract: A system for providing heated, pressurized air to a device in an industrial process, the system including at least one engine arranged and designed to heat and pressurize air, and at least one pipe attached to the at least one engine to provide a flow path for air from the at least one engine to the device in the industrial process. The system may also include an expansion joint positioned between the at least one engine and the pipe, the expansion joint arranged and designed to allow relative axial movement between the at least one engine and the pipe.

Abstract: A jack (10) of the invention includes a holding body (9) having an insertion hole (15) into which an optical plug is able to be inserted, a window material (6) through which infrared radiation passing through the insertion hole (15) is transmitted, and a light reception unit (2) which detects infrared radiation of 6 ?m or more and 15 ?m or less transmitted through the window material (6). The window material (6) is provided in the holding body (9) so as to prevent water from intruding into the light reception unit (2), and arranged at a bottom of the insertion hole (15). Thereby, it is possible to give a waterproof property to an element which receives infrared radiation without limitation to design or aesthetic appearance of an electronic apparatus.

Abstract: A nozzle arrangement for a gas turbine engine includes an engine nozzle and an ejector nozzle arranged axially downstream thereof. A gap S is formed between the outlet of the engine nozzle and the inlet of the ejector nozzle, and a flange which reduces the gap S is arranged at the outlet of the engine nozzle.

Abstract: A gas turbine exhaust diffuser includes a frustoconical portion that defines an interior surface and an axial centerline. In particular embodiments, the interior surface may have a slope greater than 6 degrees, 10 degrees, or 20 degrees with respect to the axial centerline to define an axial cross-sectional area of at least 200 square feet, 240 square feet, or 260 square feet. In other particular embodiments, the interior surface may have an axial length of less than 25 feet or less than 10 feet. A helical turbulator on the interior surface of the frustoconical portion may reduce flow separation between exhaust gases and the interior surface to enhance recovery of potential energy from the exhaust gases.

Abstract: The present disclosure relates to an engine having two modes of operation—air breathing and rocket—that may be used in aerospace applications such as in an aircraft, flying machine, or aerospace vehicle. The engine's efficiency can be maximized by using a precooler arrangement to cool intake air in air breathing mode using cold fuel used for the rocket mode. By introducing the precooler and certain other engine cycle components, and arranging and operating them as described, problems such as those associated with higher fuel and weight requirements and frost formation can be alleviated.

Abstract: An embodiment of the invention is a technique to suppress noise in a jet engine. A substantially annular fan nozzle of a separate-flow turbofan engine includes a flow boundary surface and an outlet to discharge fan air into atmosphere. At least one vane extends substantially radially from the flow boundary surface to vector at least a portion of the fan air toward a direction where noise suppression is desired. The-vane is situated in proximity of the outlet and has a span substantially greater than a thickness of a local boundary layer of the fan air.

Abstract: A mixer for mixing flows in a turbofan engine is provided. The mixer includes a plurality of chevron lobes, each of the plurality of lobes comprising a crown, a keel, a first trailing edge, a second trailing edge, and a first transverse edge extending between first trailing edge and second trailing edge, said mixer configured to receive two separate incoming exhaust flows and mix the two flows into at least one rotational exhaust flow that is ejected out at least one of said first trailing edge and said second trailing edge.

Abstract: According to the invention, the shape of each of said chevrons is defined: by two lateral sides (21, 22) having front ends (21A, 22A) that are connected to said nozzle (4, 10) and that, when moving away from the latter, converge towards each other without joining so that the rear ends (21R, 22R) of said lateral walls (21, 22) are spaced from each other; and by a curvilinear transverse line (23.1) connecting the rear ends (21R, 22R) of said lateral walls (21, 22) by forming two rounded side protrusions (24.1, 25.1) separated by an intermediate rounded recess (26.1).

Abstract: A mixer of a bypass turbine aeroengine according to one embodiment, includes circumferential inner and outer flow surfaces in a wavy configuration to form a plurality of lobes of the mixer. The mixer has an upstream end portion of sheet metal with a first thickness and a downstream end portion of sheet metal with a second thickness less than the first thickness.

Abstract: According to the invention, a plurality of embossments (20) having a rectangular section is provided at the inner periphery of the outlet opening (7) of the fan duct (12), said embossments being separated by longitudinal channels (21) having a convergent (22C) and a divergent (22D) for the cold flow (9).

Abstract: A shape memory alloy (SMA) actuated aerostructure operable to dynamically change shape according to flight conditions is disclosed. Deformable structures are actuated by SMA actuators that are coupled to face sheets of the deformable structures. Actuating the SMA actuators produces complex shape changes of the deformable structures by activating shape changes of the SMA actuators. The SMA actuators are actuated via an active or passive temperature change based on operating conditions. The SMA actuated aerostructure can be used for morphable nozzles such as a variable area fan nozzle and/or a variable geometry chevron of a jet engine to reduce engine noise during takeoff without degrading fuel burn during cruise.

Abstract: A jet flow discharge nozzle includes a tubular partition wall, a tubular casing which covers an outer periphery of the tubular partition wall, and a bifurcation which extends in an axial direction of the tubular partition wall and the casing so as to support downstream ends of the tubular partition wall and the casing from outside. Inside of the tubular partition wall is defined as a flow path for a high-speed core flow. A space between the tubular partition wall and the casing is defined as a flow path for a low-speed bypass flow. A pair of first projections is provided at a downstream edge of the tubular partition wall near the bifurcation at positions symmetric about the bifurcation. One of ridges of each of the first projections faces an upstream side. The invention reduces noise by avoiding adverse effects of the presence of the bifurcation on an increase in noise.

Abstract: An aircraft jet engine including a wall centered about a longitudinal axis and surrounding a stream of gas ejected at a downstream end of the wall in the direction of the axis, primary ducts distributed at the periphery of the downstream end of the wall configured on command each to eject a jet of primary fluid to interact with the ejected stream of gas, the primary ducts of each pair converging towards one another near the downstream end of the wall so that the primary jets ejected form two sides of a triangle that meet at the vertex thereof in a view projected onto a plane perpendicular to a transverse plane, and secondary ducts each associated with each pair of primary ducts and configured on command to eject a jet of secondary fluid directed into the triangle formed by the primary jets.

Abstract: In one embodiment, a gas turbine engine exhaust nozzle comprises a housing having a length which extends along a central longitudinal axis and comprising an interior surface and an exterior surface, and a row of chevrons extending from an aft end of the housing, the chevrons having a root region and a tip, wherein at least a portion of at least one of the interior surface or the exterior surface is scalloped proximate the root region of a chevron. Other embodiments may be described.

Abstract: An integrated, single piece mixer-center body ventilation apparatus is disclosed for use with a turbofan jet engine. The apparatus may incorporate a circumferential forward body portion adapted to be coupled to an aft end of a core engine turbine case of the jet engine, and a center body tube portion integrally formed with the forward body portion and having an axially opening vent exit. The forward body portion may have a plurality of inner mixer flow paths in communication with scalloped projecting portions. The inner mixer flow paths direct a pressurized core exhaust flow through the mixer device and mix the pressurized core exhaust flow with a portion of a pressurized fan exhaust flow, to thus significantly cool the pressurized core exhaust flow.

Abstract: A catalyst includes a carrier of essentially hafnia, up to an equal part zirconia, and optionally additional stabilizers, upon the surface of which is deposited an active metal suitable to promote the reaction of propellants to be used in gas generators and thrusters.

Abstract: An exhaust device is disclosed that includes a duct that turns an exhaust flow from a gas turbine engine from a first direction to a second direction. A diverter cup is disposed within the duct and serves to split the exhaust flow into two streams as well as introduce cooling air through an ejector pump at the downstream end of the diverter cup. A splitter is disposed downstream of the diverter cup and serves to split the cooling air into two streams which are thereafter mixed with the split exhaust flow. A diffuser is created in the exhaust device between the duct and the splitter. Various cooling slots are also provided in the duct.

Abstract: An exhaust mixer for a gas turbine engine including a plurality of circumferentially distributed alternating inner and outer lobes, where each of the inner lobes is configured with a circumferential offset between the base and the tip thereof, and a direction of the circumferential offset defined from the base to the tip of each of the inner lobes is the same for all of the inner lobes and opposite to that of a swirl component of a main gas path flow entering the exhaust mixer.

Abstract: A gas turbine engine exhaust mixer has a plurality of circumferentially distributed alternating inner and outer lobes. The outer lobes protrude into the annular bypass passage of the engine, whereas the inner lobes protrude into the main gas path passage of the engine. The inner and outer lobes respectively define alternating troughs and crest with radial interconnecting walls therebetween. The mixer has a jagged trailing edge including a plurality of tabs extending from each radial wall between the troughs and the crests.

Abstract: A thrust generator includes an air inlet configured to introduce air within the thrust generator and a plenum having a plurality of fluid injection devices. The plenum is configured to receive an exhaust gas from a gas generator and direct the exhaust gas via the plurality of fluid injection devices radially into the thrust generator and along a Coanda profile surface configured to facilitate attachment of the exhaust gas to the profile surface to form a boundary layer and to entrain incoming air from the air inlet to generate thrust. The thrust generator has a non-circular shape.

Abstract: A method of assembling an inlet air filter assembly for use with a turbine engine system. The method includes coupling an inlet hood to an air filter enclosure, such that an airflow path is defined between the inlet hood and the air filter enclosure. A pre-filter is coupled to the inlet hood, such that the pre-filter is positioned within the airflow path. A filter bypass assembly is coupled to the pre-filter for moving the pre-filter from an operating position to a bypass position during operation of the turbine engine system.

Abstract: In an air mixing arrangement wherein a primary fluid is introduced through an opening in a wall to be mixed with a secondary fluid flowing along the wall surface, the opening is airfoil shaped with its leading edge being orientated at an attack angle with respect to the secondary fluid flow stream so as to thereby enhance the penetration and dispersion of the primary fluid stream into the secondary fluid stream. The airfoil shaped opening is selectively positioned such that its angle of attack provides the desired lift to optimize the mixing of the two streams for the particular application. In one embodiment, a collar is provided around the opening to prevent the secondary fluid from contacting the surface of the wall during certain conditions of operation. Multiple openings maybe used such as the combination of a larger airfoil shaped opening with a smaller airfoil shaped opened positioned downstream thereof, or a round shaped opening placed upstream of an airfoil shaped opening.

Abstract: An aircraft jet engine including a wall centered about a longitudinal axis and surrounding a stream of gas ejected at a downstream end of the wall in the direction of the axis, primary ducts distributed at the periphery of the downstream end of the wall configured on command each to eject a jet of primary fluid to interact with the ejected stream of gas, the primary ducts of each pair converging towards one another near the downstream end of the wall so that the primary jets ejected form two sides of a triangle that meet at the vertex thereof in a view projected onto a plane perpendicular to a transverse plane, and secondary ducts each associated with each pair of primary ducts and configured on command to eject a jet of secondary fluid directed into the triangle formed by the primary jets.

Abstract: A turbine arrangement is provided for use in a gas turbine engine that includes a combustion chamber and a nozzle. The turbine arrangement includes a source of liquid and a turbine blade assembly that is rotatable about a central shaft. The blade assembly further includes a plurality of turbine blades, the blade having a forward edge that faces the combustion chamber and an opposite rear edge. A hollow interior of at least one blade is in fluid communication with the source of liquid. The blade (e.g. a rear edge thereof) including a plurality of openings in communication with the hollow interior and sized to produce liquid droplets for discharge downstream of the turbine blade to generate a gas (e.g., steam) due to contact with hot gases generated by the combustion chamber.

Abstract: A plasma enhanced rapidly expanded duct system includes a gas turbine engine inter-turbine transition duct having radially spaced apart conical inner and outer duct walls extending axially between a duct inlet and a duct outlet. A conical plasma generator produces a conical plasma along the outer duct wall. An exemplary embodiment of the conical plasma generator is mounted to the outer duct wall and including radially inner and outer electrodes separated by a dielectric material. The dielectric material is disposed within a conical groove in a radially inwardly facing surface of the outer duct wall. An AC power supply is connected to the electrodes to supply a high voltage AC potential to the electrodes.

Abstract: A centerbody for the exhaust system of a gas turbine engine having an upstream end mounted within an exhaust duct casing of the exhaust system. The centerbody includes a plurality of ventilation openings defined in a centerbody wall which provide fluid flow communication between an internal cavity and exhaust gas flow surrounding the centerbody, such that ventilating air from within the cavity can exit into the exhaust gas flow.

Abstract: An embodiment of the invention is a technique to suppress noise in a jet engine. A substantially annular fan nozzle is attached to a pylon and discharges a fan stream into atmosphere from an aft end thereof. A core nozzle discharges core stream into the atmosphere. The core nozzle has an exterior surface. A stream director is mounted on the pylon to direct the fan stream away from the pylon. At least a portion of the stream director is situated outside the aft end to maintain substantially constant flow area of the fan nozzle.

Abstract: The invention relates to a mixer for a bypass turbomachine, the mixer comprising a member having a sinusoidal portion at its end defining inner lobes and outer lobes, each outer lobe comprising a pair of plane radial walls spaced apart from each other in the circumferential direction and interconnected by an outer dome, each inner lobe comprising a pair of plane radial walls spaced apart from each other in the circumferential direction and connected together by an inner dome, the walls of the outer lobes being disposed to extend the walls of the inner lobes radially, the radial walls of a given outer lobe extending radially in mutually parallel directions, with these walls, when extended geometrically, defining a zone from which the axis of symmetry of the cylindrical member is excluded.

Abstract: A booster system is disclosed, comprising a first rotor stage having a plurality of first rotor blades spaced circumferentially around a rotor hub with a longitudinal axis and having a first pitch-line radius extending from the longitudinal axis, a last rotor stage located axially aft from the first rotor stage, the last rotor stage comprising a plurality of last rotor blades spaced circumferentially around the longitudinal axis and having a second pitch-line radius extending from the longitudinal axis, and a gooseneck duct located axially aft from the last rotor stage and capable of receiving an airflow, the gooseneck duct comprising an inlet end and an exit end located at a distance axially aft from the inlet end and having at least one plasma actuator mounted in the gooseneck duct.

Abstract: A mixer for a separate-stream turbojet nozzle, the mixer comprising along a longitudinal axis (X-X?) both a fastener shroud (10) for connecting said mixer to the exhaust casing of the nozzle, and a lobe structure (20) presenting a succession of inner and outer lobes (22 and 21) distributed circumferentially around the longitudinal axis (X-X?) of the mixer. The lobe structure (20) is made of a ceramic matrix composite material and further comprises a stiffener ring (30) that forms a connection between at least some of the lobes of said structure. Thus, the major portion of the mixer, i.e. the lobe structure, is made of a ceramic matrix composite material, thereby significantly reducing the weight of the mixer, and consequently reducing the weight of the nozzle.

Abstract: The invention relates to an annular cover for a turbomachine nozzle, the cover having a plurality of patterns extending a trailing edge of said cover and spaced apart circumferentially from one another, each pattern having an outline that is substantially triangular in shape, with a base formed by a portion of the trailing edge of the cover and a vertex spaced downstream from the base and connected thereto by two sides. For each pattern, the vertex presents an outline that is substantially curved; each side is connected to the trailing edge of the cover following an outline that is substantially curved having a radius of curvature that is greater than the radius of curvature of the outline of the vertex; and the outline of each of the sides includes at least one point of inflexion having a tangent that is substantially parallel to the base.

Abstract: Variation in the available mixing plane areas in an exhaust arrangement of a gas turbine engine enables alteration and configuration for better thermal cycle performance of that engine. A shaped centre fairing is associated with an exit nozzle and a bypass duct such that channels between the fairing, nozzle exit and duct can be adjusted to change the available areas. Such variation is achieved by relative axial displacement, typically of the exit nozzle using an appropriate mechanism.

Abstract: A system for controlling a position of jet engine exhaust mixing tabs includes a plurality of exhaust mixing tabs spaced apart from one another and extending from a lip of an exhaust nozzle of a jet engine nacelle adjacent a flow path of an exhaust flow emitted from the exhaust nozzle. Each of the exhaust mixing tabs are constructed to be controllably deformable from a first position adjacent the flow path to a second position extending into the flow path of the exhaust flow in response to a control signal applied to each of the exhaust mixing tabs. In the first position, the exhaust mixing tabs either have no affect on the thrust produced, or increase the momentum (thrust) of the exhaust flow exiting from the exhaust nozzle. In the second position, that is, the “deployed” position, the exhaust mixing tabs are deformed to extend into the flow path. In this position the exhaust mixing tabs promote mixing of the exhaust flow with an adjacent air flow.

Abstract: An InfraRed Suppression System (IRSS) includes a double-walled exhaust duct and double walled septum. The double walled structure provides a flow path for secondary (non-exhaust gas) cooling air flow to slots along the surfaces exposed to exhaust gases. Exhaust gas flow past these slots draws cooling air across the duct and septum surfaces. This flow cools the surfaces close to the slots and mixes with exhaust gasses downstream to cool the exhaust plume. The septum in the shape of a helix rotating fully blocks line-of-sight to the turbine exit from the aft of the aircraft. The exhaust duct is intended to be shrouded by an aerodynamic fairing which provides an aerodynamic contour which minimizes aerodynamic impact on the aircraft.

Abstract: A cowl for a turbomachine nozzle, the cowl having a plurality of repeated patterns disposed circumferentially at a trailing edge, each pattern being asymmetrical about a midplane of the pattern containing a longitudinal axis of the cowl, and each pattern having a first portion inclined radially towards the inside of the cowl and a second portion inclined radially towards the outside of the cowl.

Abstract: A mixer for a separate-stream turbojet nozzle, the mixer comprising along a longitudinal axis (X-X?) both a fastener shroud (10) for connecting said mixer to the exhaust casing of the nozzle, and a lobe structure (20) presenting a succession of inner and outer lobes (22 and 21) distributed circumferentially around the longitudinal axis (X-X?) of the mixer. The lobe structure (20) is made of a ceramic matrix composite material and further comprises a stiffener ring (30) that forms a connection between at least some of the lobes of said structure. Thus, the major portion of the mixer, i.e. the lobe structure, is made of a ceramic matrix composite material, thereby significantly reducing the weight of the mixer, and consequently reducing the weight of the nozzle.

Abstract: A device for reducing the jet noise of a turbomachine, the turbomachine having a longitudinal axis and a substantially cylindrical nozzle extending along the longitudinal axis of the turbomachine, having a downstream end for mixing the flows of gas inside and outside the nozzle, the device comprising a plurality of corrugations disposed to extend the downstream end of the nozzle, and a plurality of notches disposed between pairs of successive corrugations in the plurality of corrugations, and the plurality of corrugations and the plurality of notches are symmetrical relative to at least one axis perpendicular to the longitudinal axis of the turbomachine so as to generate a dual counter-rotating effect between the gas flows.

Abstract: A passive exhaust system is described that provides effective infrared signature suppression without affecting radar cross-section while maintaining stable function in crosswinds. A passive exhaust system may include an array of ducts with each duct having a primary and secondary nozzle. Central ducts draw in ambient cooling air to create a thick cooling film along exterior surfaces and cause plume dilution, stabilize the plume flow in a crosswind, and prevent heating of visible surfaces. Visible surfaces may incorporate radar absorbing materials and may be inclined at an angle or fabricated with a diffuse surface to prevent specular reflection. Visible surfaces may be constructed from or covered with low infrared emissivity materials. A variable passive flow controller ensures a sufficient velocity exhaust flow.

Abstract: A second stage external jet nozzle mixer (20) includes identically formed lobes which equal in number the lobes of the first stage internal mixer. The external mixer works with the internal mixer, and furthers the mixing of the jet engine internal bypass flow with the internal jet engine core flow. This mixing levels the disparate flow velocities attendant with the jet engine exhaust, reduces the peak velocities from the jet engine core and increases the lower bypass velocities of the jet engine internal bypass flow. The lobes include complex curvatures that greatly enhance mixing of the gases and ambient cooling air, and thereby reduce noise. At the lobe terminus, the lobe dimensional characteristics may be adjusted to thereby adjust the total terminus area to achieve a match to a jet engine to cause that jet engine to run at a determined RPM and noise level. Noise attenuation may also be adjusted by changing lobe dimensions.

Abstract: A method for operating a gas turbine engine includes channeling compressed air from the gas turbine engine to a noise suppression system, and selectively operating the noise suppression system such that air discharged from the noise suppression system generates a streamwise vortex downstream from each respective chevron.