Mechanism for accelerating heat release of combusting flows

• US 5,076,053 A
• Filed: 08/10/1989
• Issued: 12/31/1991
• Est. Priority Date: 08/10/1989
• Status: Expired due to Term

• Current Assignee: United Technologies Corporation (Rtx Corporation)
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Pelmas, Roy, Werle, Michael J., Presz, Walter M. Jr., McVey, John B., Paterson, Robert W.
• Primary Examiner(s): Bentley, Stephen C.
• Application Number:
  US07/391,916
• Time in Patent Office: 873 Days
• Field of Search: 60/261, 60/262, 60/733, 60/749
• US Class Current: 60/765
• CPC Class Codes: F23R 3/18 Flame stabilising means, e.g. flame holders for after-burners of jet-propulsion plants

Abstract

In a combustion process streams of fuel, oxidant or combinations of fuel and oxidant pass simultaneously through a combustion region over opposite sides of a plate disposed therein having downstream extending convolutions which create pairs of large scale oppositely rotating vortices. These vortices cause the fuel and oxidant to mix rapidly with each other. A recirculation zone is disposed immediately downstream and adjacent the edge of the convoluted plate, and in one embodiment is created by a step-wise discontinuity in the flowpath. The mixing occurs without introducing large momentum losses and, when the mixture is ignited immediately downstream of the convoluted plate, the flame propagates with a larger than normal spreading angle.

Claims

1. A combustor having wall means defining a conduit for carrying field, oxidant, and combustion products in a downstream direction and for burning fuel and oxidant therein, said combustor including a separator plate disposed within said conduit, said plate having first and second opposed, downstream extending surfaces over which fluids within said conduit are adapted to flow, said plate having a downstream edge and a convoluted portion comprising a plurality of adjoining, alternating lobes and troughs extending downstream, each lobe and trough being smoothly U-shaped in cross section taken transverse to the downstream direction and blending smoothly with adjacent lobes and troughs, said lobes and troughs being spaced from said combustor wall means and terminating at said downstream edge, said lobe height and trough depth increasing continuously in the downstream direction to its maximum at said downstream edge, the contours and dimensions of said troughs and lobes being selected to ensure that each trough flows full and generates a pair of adjacent, large scale counterrotating vortices downstream of said edge within said conduit, each of said vortices rotating about an axis extending in the downstream direction, said combustor including means for creating and maintaining a recirculating flow region immediately adjacent and downstream of said downstream edge, said recirculation creating means including a step-wise increase in the cross-sectional flow area of said conduit immediately downstream of said downstream edge.

2. In a combustion process within a combustor having wall means defining a combustion chamber, the chamber having a separator plate disposed therewithin spaced from the chamber walls and extending in the downstream direction, the plate having a plurality of adjoining, alternating lobes and troughs extending downstream and terminating at the downstream edge of the plate, the improvement comprising:

creating a recirculating fluid region adjacent, immediately downstream of and extending substantially along the full length of the downstream edge of the plate, and transversely offset from the trough outlets;

flowing fluid in the downstream direction within the chamber over the lobes and within the troughs on each side of the plate, the bulk fluid flow on each side of the plate having substantially no angular momentum as it enters the troughs, wherein the fluid flowing over the plate includes a fuel and an oxidant;

maintaining full flow within the troughs during combustion;

rapidly mixing together the fluids on opposite sides of the plate by generating pairs of adjacent counterrotating vortices downstream of the plate, each pair of vortices made up of fluid from both sides of the plate, each of the vortices rotating about an axis extending in the downstream direction, and each vortex having a diameter on the scale of the depth of the downstream end of the trough; and

causing the mixture of fluids to ignite within the recirculating fluid region immediately downstream of the plate and to have the upstream end of the flame remain attached at such location during combustion.

3. A combustor having wall means defining a conduit for carrying fuel, oxidant, and combustion products in a downstream direction and for burning fuel and oxidant therein, said combustor including a separator plate disposed within said conduit, said plate having first and second opposed, downstream extending surfaces over which fluids within said conduit are adapted to flow, said conduit including a first flow surface spaced from and facing said separator plate first surface and defining a downstream extending first flow path therebetween for a first fluid, said conduit also including a second downstream extending flow surface spaced from and facing said separator plate second surface and defining a downstream extending second flow path therebetween for a second fluid, said separator plate having a downstream edge and a convoluted portion comprising a plurality of adjoining, alternating lobes and troughs extending downstream, each lobe and trough being smoothly U-shaped in cross section taken transverse to the downstream direction and blending smoothly with adjacent lobes and troughs, said lobes and troughs being spaced from said combustor wall means and terminating at said downstream edge, said lobe height and trough depth increasing continuously in the downstream direction to its maximum at said downstream edge, the contours and dimensions of said troughs and lobes being selected to ensure that each trough flows full and generates a pair of adjacent, large scale counterrotating vortices downstream of said edge within said conduit, each of said vortices rotating about an axis extending in the downstream direction, wherein said convoluted downstream edge of said separator plate is adjacent said first conduit flow surface and said first conduit flow surface extends in the downstream direction over the length of said convoluted portion, wherein at said downstream edge of said separator plate said first conduit flow surface extends transversely of the downstream direction away from said separator plate first surface to create a recirculating flow region within said combustor immediately adjacent and downstream of said downstream edge.

4. The combustor according to claim 3 wherein said first flow path cross sectional flow area is substantially constant over the length of said convoluted portion.

5. A combustor having wall means defining a conduit for carrying fuel, oxidant, and combustion products in a downstream direction and for burning fuel and oxidant therein, said combustor including a separator plate disposed within said conduit, said plate having first and second opposed, downstream extending surfaces over which fluids within said conduit are adapted to flow, said plate having a downstream edge and a convoluted portion comprising a plurality of adjoining, alternating lobes and troughs extending downstream, each lobe and trough being smoothly U-shaped in cross section taken transverse to the downstream direction and blending smoothly with adjacent lobes and troughs, wherein each of said troughs has a pair of facing side walls, and each pair of said side walls of the troughs in at least one surface of said separator plate are substantially parallel to each other over their length, said lobes and troughs being spaced from said combustor wall means and terminating at said downstream edge, said lobe height and trough depth increasing continuously in the downstream direction to its maximum at said downstream edge, the contours and dimensions of said troughs and lobes being selected to ensure that each trough flows full and generates a pair of adjacent, large scale counterrotating vortices downstream of said edge within said conduit, each of said vortices rotating about an axis extending in the downstream direction, said combustor including means for creating and maintaining a recirculating flow region immediately adjacent and downstream of said downstream edge.

6. The combustor according to claim 5 wherein said side walls of each trough in both said first and second surfaces of said separator plate are substantially parallel to each other.

7. The combustor according to claim 5 wherein the aspect ratio of the troughs formed in at least one of said surfaces of said separator plate is between 2.0 and 10.0.

8. The combustor according to claim 7 wherein in at least one of said surfaces of said separator plate the slope of the troughs at said downstream edge is at least 10 degrees.

9. The combustor according to claim 7 wherein the trough depth at said plate downstream edge is at least 25 percent of the distance across said conduit as measured in the direction of trough depth.

10. The combustor according to claim 6, wherein the aspect ratio of the troughs formed in at least one of said surfaces of said separator plate is between 2.0 and 7.5, the slope of the troughs in at least one of said surfaces is at least 15°

and the trough depth at said plate downstream edge is at least 25 percent of the distance across said conduit as measured in the direction of trough depth.

11. Afterburner means for a gas turbine engine, including wall means defining a conduit for carrying fuel, oxidant, and combustion products in a downstream direction and for burning fuel and oxidant therein, said afterburner including a pair of separator plates disposed within said conduit, each plate having first and second opposed, downstream extending surfaces over which fluids within said conduit are adapted to flow, each plate having a downstream edge and a convoluted portion comprising a plurality of adjoining, alternating lobes and troughs extending downstream, each lobe and trough being smoothly U-shaped in cross section taken transverse to the downstream direction and blending smoothly with adjacent lobes and troughs, said lobes and troughs being spaced from said afterburner wall means and terminating at said downstream edge, said lobe height and trough depth increasing continuously in the downstream direction to its maximum at said downstream edge, the contours and dimensions of said troughs and lobes being selected to ensure that each trough flows full and generates a pair of adjacent, large scale counterrotating vortices downstream of said edge within said conduit, each of said vortices rotating about an axis extending in the downstream direction, said afterburning means including a gutter of V-shaped cross section disposed within said conduit between said pair of plates and adjacent the convolutions of each plate, and located so as to create a recirculating flow region immediately adjacent and downstream of said downstream edge of said separator plates, said afterburner means also including fuel spray means upstream of said separator plate and gutter.

12. The combustor according to claim 11, wherein said gutter and said plates are annular, and the depth and height of said troughs and lobes is a radial dimension.

13. In a combustion process within a combustor having wall means defining a combustor chamber, the chamber having a separator plate disposed therewithin spaced from the chamber walls and extending in the downstream direction, the plate having a plurality of adjoining, alternating lobes and troughs extending downstream and terminating at their maximum height and depth, respectively, at the downstream edge of the plate, the improvement comprising:

flowing fluid in the downstream direction within the chamber over the lobes and within the troughs on each side of the plate, the bulk fluid flow on each side of the plate having substantially no angular momentum as it enters the troughs, wherein the fluid flowing over the plate includes a fuel and an oxidant, and wherein the bulk fluid on one side of the plate flows at a downstream velocity several times faster than the bulk fluid flowing on the other side of the plate and the slower of the two fluids is substantially entirely fuel;

maintaining full flow within the troughs during combustion;

rapidly mixing together the fluids on opposite sides of the plate by generating pairs of adjacent counterrotating vortices downstream of the plate, each pair of vortices made up of fluid from both sides of the plate, each of the vortices rotating about an axis extending in the downstream direction, and each vortex having a diameter on the scale of the depth of the downstream end of the trough; and

causing the mixture of fluids to ignite immediately downstream of the plate and to remain lit at such location.

14. The combustion process according to claim 13, including the step of creating a recirculating fluid region adjacent, immediately downstream of and extending substantially along the full length of the downstream edge of the separator plate and transversely offset therefrom.