Inlet duct

Claim 2

An inlet duct for a supersonic aircraft; said duct comprising walls defining an intake channel, the walls being arranged such that the cross-sectional area at the inlet to the intake channel is greater than the cross-sectional area of a downstream throat portion in the channel whereby the air introduced into the channel is compressed as it flows toward the throat, the walls beIng further arranged to induce at least one shock wave when the velocity of the airstream ahead of the inlet is supersonic, the shock wave being normally disposed within the channel and forming a transition from supersonic to subsonic flow therein, and a vent aperture in at least one of the walls for permitting the spillage of a sufficient amount of air from the portion of the intake channel located behind the shock wave to avoid chocking the airstream in the channel as the airstream ahead of the channel passes from a subsonic to a supersonic velocity so that the shock wave may move downstream through the channel to a stabilized position in the vicinity of the throat, the vent aperture extending longitudinally in the channel across the shock wave when the shock wave is in its stabilized position so that a portion of the aperture is disposed ahead of the shock wave and another portion is disposed behind the shock wave, whereby air spills out of the channel from the subsonic region thereof and the shock wave remains stabilized in the throat, the width of the vent aperture increasing as the cross-sectional area of the channel decreases.

Claim 3

An inlet duct according to claim 1 wherein the aperture is generally triangular in shape.

Claim 4

An inlet duct for the jet engine of an aircraft; said inlet duct comprising fixed walls partially defining an inlet channel; a first ramp shiftable relative to the fixed walls and also defining a portion of the inlet channel; the inlet channel having a throat, the cross-sectional area of which varies as the first ramp shifts; a second ramp located forwardly of the first ramp and extending from the intake channel, the second ramp pivoting relative to the fixed walls about an axis extending transversely of the channel and having a leading edge located forwardly from the pivot axis so that the capture area of the duct varies as the second ramp pivots, the second ramp upon encountering supersonic airstreams inducing a shock wave which forms a transition from a region of high velocity and low pressure to a region of lower velocity and higher pressure; and a sideplate mounted on the second ramp and aligning with and leading up to at least one of the fixed walls, the sideplate extending along the region of lower velocity and higher pressure for retarding the leakage of air from that region before the air enters the portion of the channel defined in part by the fixed walls.

Claim 5

An inlet duct for the jet engine of an aircraft; said inlet duct comprising fixed walls partially defining an inlet channel; a first ramp shiftable relative to the fixed walls and also defining a portion of the inlet channel; the inlet channel having a throat, the cross-sectional area of which varies as the first ramp shifts; a second ramp located forwardly of the first ramp and extending from the intake channel, the second ramp pivoting relative to the fixed walls about an axis extending transversely of the channel and having a leading edge located forwardly from the pivot axis so that the capture area of the duct varies as the second ramp pivots, the second ramp upon encountering supersonic airstreams inducing a shock wave which forms a transition from a region of high velocity and low pressure to a region of lower velocity and higher pressure; and a sideplate mounted on the second ramp and aligning with and leading up to at least one of the fixed walls, the sideplate extending along the region of lower velocity and higher pressure for retarding the leakage of air from that region before the air enters the portion of the channel defined in part by the fixed walls.

Claim 6

An inlet duct according to claim 3 wherein the second ramp has a compression surface which forwardly terminates at the leading edge of the ramp and diverts the airstream.

Claim 7

An inlet duct according to claim 4 wherein the compression surface is located on the same side of the channel as the first ramp; and wherein the sideplate is presented substantially perpendicular to the compression surface.

Claim 8

An inlet duct according to claim 5 wherein the channel at its entrance and at the first ramp is generally rectangular; and wherein one of the fixed walls forms a third ramp having a leading edge set rearwardly from the leading edge of the second ramp but ahead of the first ramp, the leading edge of the third ramp inducing another shock wave across which another reduction in air velocity and increase in pressure occurs.

Claim 9

An inlet duct according to claim 6 wherein the shock waves induced by the leading edges of the second and third ramps are oblique to the direction of airflow along the ramps; and wherein still another shock wave is induced in the channel in the vicinity of the throat, the throat shock wave being substantially normal to the flow of air through the channel and forming a transition from supersonic to subsonic air velocities in the channel.

Claim 10

An inlet duct according to claim 4 wherein the channel at its entrance and at the first ramp is generally rectangular; wherein one of the fixed walls forms a third ramp located on the opposite side of the channel from the first and second ramps and having a leading edge set rearwardly from the leading edge on the secOnd ramp but ahead of the first ramp; and wherein the axis about which the second ramp pivots is located intermediate the ends of the compression surface and the rear end of the compression surface is located opposite to the third ramp at the throat of the channel, whereby both the throat area and capture area of the duct are altered as the second ramp pivots.

Claim 11

An inlet duct according to claim 8 wherein the first ramp is pivoted about an axis extending transversely of the channel and set rearwardly from the throat area; wherein the first ramp generally aligns with the second ramp and forms an aft continuation thereof; and wherein connecting means connect the first and second ramps in the vicinity of the throat area for enabling the first and second ramp to move in unison and remain generally in alignment.

Claim 12

An inlet duct according to claim 6 wherein the fixed walls include upstanding sidewalls between the sides of the first ramp and the third ramp.

Claim 13

An inlet duct according to claim 10 and further characterized by a vent in at least one of the sidewalls for allowing air to spill out of the channel from the subsonic region behind the normal shock wave, whereby the shock waves are stabilized in the channel.

Claim 14

An inlet duct according to claim 11 wherein the vent is an opening in one of the walls extending longitudinally therein such that a portion of the opening is disposed downstream from the normal shock wave and another portion is disposed upstream ahead of the normal shock wave, whereby the flow within the channel will not be choked during the transient period when the shock waves are being established, enabling the shock waves to move to their stabilized positions.

Claim 15

An inlet duct for the jet engine of an aircraft; said inlet duct comprising opposed and generally parallel fixed walls partially defining an inlet channel, a ramp extending forwardly from the intake channel and pivoted relative to the fixed walls about an axis extending generally perpendicular to those fixed walls, the ramp having a leading edge located forwardly from the pivot axis so that the capture area of the duct varies as the ramp pivots, the ramp upon encountering supersonic airstreams inducing a shock wave which forms a transition from a region of relatively high velocity and low pressure to a region of lower velocity and higher pressure, and a sideplate mounted rigidly on the ramp and aligning with one of the fixed walls so as to form a forward continuation of that wall along the region of lower velocity and higher pressure, whereby the leakage of air from that region is retarded.

Claim 16

An inlet duct for the jet engine of an aircraft; said inlet duct comprising opposed and generally parallel fixed walls partially defining an inlet channel, a ramp extending forwardly from the intake channel and pivoted relative to the fixed walls about an axis extending generally perpendicular to those fixed walls, the ramp having a leading edge located forwardly from the pivot axis so that the capture area of the duct varies as the ramp pivots, the ramp upon encountering supersonic airstreams inducing a shock wave which forms a transition from a region of relatively high velocity and low pressure to a region of lower velocity and higher pressure, and a sideplate mounted rigidly on the ramp and aligning with one of the fixed walls so as to form a forward continuation of that wall along the region of lower velocity and higher pressure, whereby the leakage of air from that region is retarded.

Claim 17

An inlet duct according claim 13 wherein a fixed ramp connects the opposed and parallel fixed walls and is located on the opposite side of the channel from the pivoted ramp, the fixed ramp having a leading edge located rearwardly from the leading edge of the pivoted ramp.

Claim 18

An inlet duct according to claim 14 wherein the shock wave induced by the pivoted ramp emanates from the leading edge of that ramp and is located oblique to the airstream flowing along the pivoted ramp; and wherein the fixed ramp also induces a shock wave which emanates from the leading edges thereof and extends into the intake channel oblique to the airstream flowing along that ramp.

Claim 19

An inlet duct according to claim 14 and further comprising another ramp located rearwardly from the pivoted ramp and being pivoted relative to the opposed and parallel fixed walls about an axis located generally perpendicular to those fixed walls; and connecting means interconnecting the forward and rear pivoted ramps to enable those ramps to pivot in unison with the leading edge of the forward ramp in general alignment with the leading edge of the rear ramp.

Claim 20

An inlet duct according to claim 13 wherein the opposed and parallel fixed walls are generally vertical and one is positioned adjacent to the fuselage of the aircraft; wherein the sideplate on the pivoted ramp aligns with the fixed inlet wall located furthest frOm the fuselage; and wherein the side of the pivoted ramp located opposite to the side to which the sideplate is attached is located adjacent to the fuselage.

Claim 21

An inlet duct for a jet engine of a supersonic aircraft; said inlet duct comprising opposed and generally parallel fixed walls, opposed ramps extending between the fixed walls generally perpendicular thereto and together with the fixed walls defining an intake channel, the ramps having longitudinally offset leading edges and generally converging from those leading edges to a throat area in the intake channel so that the cross-sectional area of the channel is greater at its inlet than at its throat, the ramps being arranged to induce a shock wave in the airstream entering the channel as the airstream ahead of the channel passes from subsonic to supersonic velocities, the shock wave forming a transition from supersonic to subsonic velocities and advancing downstream in the channel to a stabilized position in the vicinity of the throat, a bleed an opening in at least one of the ramps for bleeding off the boundary layer along that ramp, and a continuously open vent aperture of constant area in at least one of the fixed walls and extending longitudinally therein, the vent aperture commencing slightly rearwardly of the rearmost leading ramp edge and terminating behind the shock wave when the shock wave is in its stabilized position, the vent aperture further being sized to permit the spillage of a sufficient amount of air from the portion of the intake channel behind the shock wave as the shock wave advances toward the throat contemporaneous with the airstream ahead of the duct passing from subsonic to supersonic velocities, whereby the shock wave will move through the channel to its stabilized position and when the shock wave reaches the stabilized position air will spill from the subsonic region behind it and stabilize it in the vicinity of the throat.

Claim 22

An inlet duct for a jet engine of a supersonic aircraft; said inlet duct comprising opposed and generally parallel fixed walls, opposed ramps extending between the fixed walls generally perpendicular thereto and together with the fixed walls defining an intake channel, the ramps having longitudinally offset leading edges and generally converging from those leading edges to a throat area in the intake channel so that the cross-sectional area of the channel is greater at its inlet than at its throat, the ramps being arranged to induce a shock wave in the airstream entering the channel as the airstream ahead of the channel passes from subsonic to supersonic velocities, the shock wave forming a transition from supersonic to subsonic velocities and advancing downstream in the channel to a stabilized position in the vicinity of the throat, a bleed an opening in at least one of the ramps for bleeding off the boundary layer along that ramp, and a continuously open vent aperture of constant area in at least one of the fixed walls and extending longitudinally therein, the vent aperture commencing slightly rearwardly of the rearmost leading ramp edge and terminating behind the shock wave when the shock wave is in its stabilized position, the vent aperture further being sized to permit the spillage of a sufficient amount of air from the portion of the intake channel behind the shock wave as the shock wave advances toward the throat contemporaneous with the airstream ahead of the duct passing from subsonic to supersonic velocities, whereby the shock wave will move through the channel to its stabilized position and when the shock wave reaches the stabilized position air will spill from the subsonic region behind it and stabilize it in the vicinity of the throat.

Claim 23

An inlet duct according to claim 18 wherein the shock wave at the throat stands generally normal to the flow of the airstream at the throat, and wherein at least one other shock wave is induced by the ramps, the other shock wave being oblique to the flow of the airstream.

Claim 24

An inlet duct according to claim 18 wherein the vent aperture is continuous from its forward to its rear ends.