Abstract
Disclosed is a vortex generating device having a body, extending between a leading edge and a trailing edge. The body, in profile cross sections taken across the spanwise direction, exhibits an airfoil-shaped geometry. Each airfoil-shaped profile cross section has a camber line extending from the leading edge to the trailing edge, at least two of the camber lines exhibiting different camber angles, such that the body exhibits at least two different flow deflection angles along the spanwise extent. An imaginary trailing edge diagonal extends straight from a first spanwise end of the trailing edge to a second spanwise end of the trailing edge. When seen from the downstream viewpoint, the trailing edge crosses the imaginary trailing edge diagonal exactly once at one diagonal crossing point.
Claims
1. A vortex generating device comprising: a body having a leading edge and a trailing edge, a streamwise direction (l) extending from the leading edge to the trailing edge, the body further exhibiting a spanwise extent extending along a spanwise direction (s); the body, in profile cross sections taken across the spanwise direction, exhibiting an airfoil-shaped geometry, each airfoil-shaped profile cross section having a camber line extending from the leading edge to the trailing edge, at least two of the camber lines exhibiting different camber angles, such that the body exhibits at least two different flow deflection angles along the spanwise extent; a first surface extending between the leading edge and the trailing edge and having airfoil-shaped profile lines on a first side of the respective camber lines and a second surface extending between the leading edge and the trailing edge, and having airfoil-shaped profiles on an opposite second side of the respective camber lines, and the first and second surface joining each other at the leading edge and at the trailing edge; wherein the trailing edge extends from a first spanwise end to a second spanwise end, and the trailing edge, when seen from a downstream viewpoint, includes a first section which is convexly shaped on a side of the first surface and is concavely shaped on a side of the second surface, and includes a second section which is concavely shaped on a side of the first surface and is convexly shaped on a side of the second surface; an imaginary trailing edge diagonal extending straight from the first spanwise end of the trailing edge to the second spanwise end of the trailing edge, wherein when seen from the downstream viewpoint, the trailing edge crosses the imaginary trailing edge diagonal exactly once at one diagonal crossing point; and wherein the trailing edge, when seen from the downstream viewpoint, comprises: at least two trailing edge segments which abut each other at a nonzero angle, and wherein the nonzero angle between each of the at least two trailing segments is an obtuse angle.
2. The vortex generating device according to claim 1, wherein the trailing edge, when seen from the downstream viewpoint, comprises: exactly one first section which extends from the first spanwise end and wherein the trailing edge is convexly shaped on a side of the first surface and is concavely shaped on a side of the second surface; and exactly one second section which extends from the second spanwise end and wherein the trailing edge is concavely shaped on the side of the first surface and is convexly shaped on the side of the second surface.
3. The vortex generating device according to claim 1, wherein the trailing edge, when seen from the downstream viewpoint, is symmetric to the diagonal crossing point.
4. The vortex generating device according to claim 1, wherein the trailing edge is shaped such that at least one imaginary trailing edge mean line exists which, when seen from the downstream viewpoint, is parallel to the leading edge and equidistant from the first spanwise end of the trailing edge and the second spanwise end of the trailing edge, and wherein in a course of the trailing edge extending along a spanwise extent and starting from the diagonal crossing point to any of the first and second spanwise ends of the trailing edge, a distance (h) of the trailing edge from the imaginary trailing edge mean line, when seen from the downstream viewpoint, monotonically increases.
5. The vortex generating device according to claim 1, wherein the trailing edge is shaped such that an imaginary trailing edge mean line exists which, when seen from the downstream viewpoint, is equidistant from the first spanwise end of the trailing edge and the second spanwise end of the trailing edge, and wherein the trailing edge at the spanwise ends, or any tangent to the trailing edge at the spanwise ends, respectively, extends parallel to the imaginary trailing edge mean line.
6. The vortex generating device according to claim 5, wherein the imaginary trailing edge mean line, when seen from the downstream viewpoint, extends parallel to the leading edge.
7. The vortex generating device according to claim 1, wherein the trailing edge, when seen from the downstream viewpoint, comprises: at least one curved trailing edge segment.
8. The vortex generating device according to claim 1, wherein the at least two trailing edge segments, when seen from the downstream viewpoint, comprises: a first straight trailing edge segment extending from the first spanwise end of the trailing edge to an inner end of the first straight trailing edge segment, a second straight trailing edge segment extending from the second spanwise end of the trailing edge to an inner end of the second straight trailing edge segment, and a third straight trailing edge segment which abuts the first and the second straight trailing edge segments at their inner ends and crosses the imaginary trailing edge diagonal.
9. The vortex generating device according to claim 1, wherein the trailing edge, when seen from the downstream viewpoint, extends in a curved manner between the first spanwise end and the second spanwise end of the trailing edge.
10. The vortex generating device according to claim 1, wherein a smallest angle (a) enclosed by any two trailing edge segments, or any tangents of trailing edge segments, respectively, when seen from the downstream viewpoint, is larger than 90.
11. The vortex generating device according to claim 1, configured as a fuel discharge device, comprising: at least one fuel supply plenum is inside the body; and at least one fuel discharge opening is at the trailing edge, whereby the fuel discharge opening is in fluid communication with a fuel supply plenum.
12. The vortex generating device according to claim 1, wherein the obtuse angle between the each of the at least two trailing segments is at least 93 degrees or larger.
13. A sequential combustion system, comprising: an upstream combustion stage; and a downstream combustion stage, wherein the downstream combustion stage is in fluid communication with the upstream combustion stage and configured to receive combustion gases from the upstream combustion stage, wherein at least one vortex generating device according to claim 1 is provided upstream the downstream combustion stage as a fuel discharge device.
14. A gas turbine engine, comprising: a sequential combustion system according to claim 13.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) The subject matter of the present disclosure is now to be explained in more detail by means of selected exemplary embodiments shown in the accompanying drawings. The figures show
(2) FIG. 1 a first exemplary embodiment of a vortex generating device of the kind outlined above;
(3) FIG. 2 a second exemplary embodiment of a vortex generating device of the kind outlined above;
(4) FIG. 3 a view of the trailing edge of the embodiment of FIG. 1 from downstream the vortex generating device;
(5) FIG. 4 a view of the trailing edge of the embodiment of FIG. 2 from downstream the vortex generating device;
(6) FIG. 5 a cross sectional view of an exemplary embodiment of a gas turbine engine comprising a multitude of vortex generating devices according to the present disclosure;
(7) FIG. 6 a plan view onto a vortex generating device with a tipped trailing edge;
(8) FIG. 7 a plan view onto a vortex generating device with a recessed trailing edge;
(9) FIG. 8 a longitudinal section of a flow duct of a gas turbine engine depicting a plan view onto a vortex generating device, wherein the trailing edge is slanted in a first direction; and
(10) FIG. 9 a longitudinal section of a flow duct of a gas turbine engine depicting a plan view onto a vortex generating device, wherein the trailing edge is slanted in a second direction.
(11) It is understood that the drawings are highly schematic, and details not required for instruction purposes may have been omitted for the ease of understanding and depiction. It is further understood that the drawings show only selected, illustrative embodiments, and embodiments not shown may still be well within the scope of the herein disclosed and/or claimed subject matter.
EXEMPLARY MODES OF CARRYING OUT THE TEACHING OF THE PRESENT DISCLOSURE
(12) FIG. 1 shows a first embodiment of the vortex generating device as herein disclosed. Vortex generating device 1 comprises a body 10. Body 10 is generally aerodynamically shaped. Body 10 comprises leading edge 11 and trailing edge 12. Body 10 extends along streamwise direction l from the leading edge to the trailing edge, and along a spanwise direction s. In the present exemplary embodiment, leading edge 11 and trailing edge 12 extend along or parallel to the spanwise direction. However, each of the trailing edge and the leading edge may be provided at an angle with the spanwise direction in a plane spanned up by the streamwise direction and the spanwise direction, such that for instance the chord length varies over the spanwise direction. Cross-sections taken across the spanwise direction exhibit airfoil-shaped geometries. Two exemplary airfoil-shaped cross sections are indicated at 14 and 15. It may be said that body 10 is generated in staggering a multitude of profile cross-sections along the spanwise direction. Each of the airfoil-shaped profile cross-sections comprises a camber line and a flow deflection angle. The camber line of profile cross section 14 is as an example denoted at 13. Further, each profile cross-section is delimited by a profile line. Although these elements are not explicitly illustrated, they are perfectly clear to the skilled person. As is seen, profile cross-sections 14 and 15 exhibit different flow deflection angles. In the shown particular embodiment, the camber angles and flow deflection angles, respectively, of profile cross-sections 14 and 15 have identical absolute values, while the arithmetic sign is different, such that the flow deflection is effected in opposing directions. It may thus be said that the body exhibits different flow deflection angles along the spanwise direction s. In the exemplary embodiment shown, at least essentially the same share of total mass flow is deflected upward in the present depiction as is deflected downward in the present depiction. Consequently, the mean, overall flow deflection effected by body 10 is at least essentially zero. It is noted, that this is not mandatory so, but the body of the vortex generation device may be provided such as to effect a nonzero mean flow deflection, as is disclosed for instance in EP 2 522 911, refer in particular to FIG. 4 in said document. It is, however, not significant to the teaching of the present disclosure whether the mean flow deflection is zero or nonzero, and thus an exemplary embodiment with a zero mean deflection has been chosen for the ease of depiction. On a first side of the camber lines of the profile cross-sections the body comprises a first surface 16. It may be said that the first surface 16 comprises all profile lines of all profile cross-sections which are located on a first side of the respective camber line. Opposite first surface 16, and not visible in the present depiction, a second surface 17 is disposed. Second surface 17 comprises all profile lines of all profile cross-sections which are located on a second side of the respective camber line. Aerodynamically shaped body 10 generally extends from leading edge 11 to trailing edge 12. Leading edge 11 extends along spanwise direction s. Arrow 20 denotes a nominal incident flow direction to the vortex generating device 1, or to body 10, respectively. As indicated above, body 10 has a camber line at each spanwise position, wherein towards the downstream end of the body 10 the camber line is different at different spanwise positions. Trailing edge 12 extends from a first trailing edge spanwise end 121 to a second trailing edge spanwise end 122. As becomes best appreciated in further view of FIG. 3, which depicts a view of trailing edge 12 from a viewpoint which is located downstream of trailing edge 12, an imaginary trailing edge diagonal may be defined as an imaginary straight line extending form first spanwise end 121 to second spanwise end 122. Trailing edge diagonal 131 is not shown in FIG. 1, but in FIG. 3. Trailing edge diagonal 131 and trailing edge 12, in a view from the downstream viewpoint, cross each other exactly once at a crossing point 151. Further, an imaginary trailing edge mean line 141 may be defined in said view from a downstream viewpoint. A trailing edge mean line may be defined as being equidistant form both spanwise ends 121 and 122 of the trailing edge. It may further be defined as additionally crossing the trailing edge at crossing point 151. Specific imaginary trailing edge mean line 141 is in the shown embodiment provided such that tangents to the trailing edge at both spanwise ends, one of which is exemplarily denoted at 129, extend parallel to said specific imaginary trailing edge mean line 141. Moreover, in the shown exemplary embodiment imaginary trailing edge mean line 141 extends parallel to leading edge 11 when seen from the downstream viewpoint, and is in said view more in particular congruent with leading edge 11. A first section 123 of the trailing edge extends between the first spanwise end 121 of the trailing edge and crossing point 151. A second section 124 of trailing edge 12 extends between second spanwise end 122 of the trailing edge and crossing point 151. First section 123 is convexly shaped on the side of first surface 16 and is concavely shaped on the side of second surface 17, while second section 124 is concavely shaped on the side of first surface 16 and is convexly shaped on the side of second surface 17. Body 10 thus comprises two lobes extending on different sides of the imaginary trailing edge mean line 141 in a trailing edge or downstream region, wherein one lobe bulges out towards the side of first surface 16 and the other one bulges out towards the side of second surface 17. When seen from the downstream viewpoint, the trailing edge exhibits a generally undulating shape. A flow flowing over body 10 along incident flow direction 20 will thus, in a downstream region of body 10 and adjacent first trailing edge section 123, result in a comparatively higher pressure on the side of surface 16 when compared to the pressure on the side of surface 17. On the other hand, adjacent second trailing edge section 124 it will result in a comparatively higher pressure on the side of surface 17 when compared to the pressure on the side of surface 16. A pressure difference in the streamwise direction is thus induced. Compensation flows over the generally undulating trailing edge will in turn generate vortices at the trailing edge of aerodynamic body 10 in a manner known per se to the skilled person. These vortices may for an instance be utilized to admix a fuel discharged at the trailing edge of body 10 into a gas flow inflowing along incident flow direction 20 and flowing around body 10. Fuel discharge nozzles or openings at the trailing edge are not shown in the simplified exemplary embodiments, but are known to the skilled person for instance by virtue of the art cited above.
(13) It will be readily appreciated by virtue of FIGS. 1 and 3 that, when for instance following the trailing edge from the first spanwise end to the second spanwise end, the trailing edge, when seen from the downstream viewpoint, is right-handed curved in first trailing edge section 123 and is left-handed curved in second trailing edge section 124. There is exactly one right-handed curved section and exactly one left-handed curved section, and one inflection point provided therebetween. In another aspect, trailing edge 12 extends in a waveform along the spanwise direction, and undulates along the spanwise extent on both sides of imaginary mean line 141, and crosses imaginary mean line 141 at crossing point 151. In the shown embodiment, crossing point 151 is identical with an inflection point of undulating trailing edge 12. As will be readily appreciated, waveform shaped trailing edge 12 extends over one half wavelength or less of the wave, and may thus be referred to as a half wavelength trailing edge. The maximum distance h of the trailing edge from imaginary mean line 141 is thus found at the spanwise ends 121 and 122. It has been shown that by virtue of providing a trailing edge which undulated over at maximum one half undulation wavelength, as compared with other embodiments in which the trailing edge undulates over more one half wavelength, the total pressure loss of the flow around the body may be significantly reduced without an overdue deterioration of the mixing homogeneity at a certain distance downstream the body. It has furthermore been discovered, that by virtue of providing a trailing edge which undulates over at maximum one half wavelength, as compared with embodiments in which the trailing edge undulates over more than one undulation wavelength, the undulation amplitude of the trailing edge, or lobe height, h, may be increased without increasing the total pressure loss, which in turn has a beneficial effect on the mixing homogeneity downstream the body.
(14) While the embodiment of FIG. 1 comprises a curved trailing edge 12, FIG. 2 shows an embodiment with a cornered or kinked trailing edge. A segment 125 of the trailing edge extends straight and parallel to imaginary mean line 141 from a first spanwise end 121 of trailing edge 12. A second segment 126 of trailing edge 12 extends straight and parallel to imaginary mean line 141 from the second spanwise end of trailing edge 12. A central straight segment 127 of trailing edge 12 abuts and connects outer segments 125 and 126. FIG. 4 depicts trailing edge 12 of the embodiment of FIG. 2 when seen from the downstream viewpoint. As will be fully appreciated by virtue of a combined view of FIGS. 2 and 4, abutting trailing edge segments form kinks or corners of the trailing edge. An imaginary trailing edge diagonal 131 extends straight between the first and second spanwise ends if the trailing edge and crosses trailing edge 12 at crossing point 151. An imaginary trailing edge mean line 141 exists for which both outer straight section 125 and 126 extend parallel to the imaginary trailing edge mean line, at a distance h. In other respects, the definition of a trailing edge mean line corresponds to the one given in connection with the embodiment of FIGS. 1 and 3. Again, the specific imaginary trailing edge mean line 141 may, in a view from the downstream viewpoint, extend parallel and in certain embodiments congruent to leading edge 11. When following the trailing edge mean line from first spanwise end 121 to second spanwise end 122 it may be said that trailing edge 12 exhibits a first section 123 in which it is right-handed kinked, and a second section 124 in which it is left-handed kinked. In an aspect, it may be said that trailing edge 12, when seen from the downstream viewpoint, extents in a cornered or polygonial waveform, and extends over at maximum one half wavelength of the waveform. Trailing edge 12, in first section 123, is convexly shaped on the side of first surface 16 and is concavely shaped on the side of second surface 17, while in second section 124 trailing edge 12 is concavely shaped on the side of first surface 16 and is convexly shaped on the side of second surface 17. Body 10 thus comprises two lobes extending on different sides of the imaginary trailing edge mean line 141 in a trailing edge or downstream region, wherein one lobe bulges out towards the side of first surface 16 and the other one bulges out towards the side of second surface 17.
(15) In both embodiments shown in FIGS. 1 and 3, and 2 and 4, respectively, the trailing edge is shown symmetric to diagonal crossing point 151. While this is a well-conceivable embodiment, other embodiments which are not symmetric are readily conceivable by the skilled person. In another aspect, in both embodiments the trailing edge, when viewed from downstream, comprises only straight or only curved segments. Embodiments in which curved and straight segments are combined with each other are known to the skilled person, in particular in view of the disclosure of EP 2 725 301. However, the body of the vortex generating device according to the teaching of the present disclosure will in any case exhibit a maximum lobe height, or a maximum distance of the trailing edge from the imaginary mean line, respectively, on both sides of crossing point 151 at the respective spanwise end of the trailing edge. In other words, on each side of the crossing location the distance of the trailing edge from the imaginary mean line does not exceed the distance h at the respective spanwise end.
(16) Further, with reference to FIGS. 3 and 4, an angle a is shown which is enclosed by two trailing edge segments. In this respect, a curved trailing edge section may in one aspect also be thought of as consisting of infinitesimally small straight segments abutting each other at an infinitesimal deviation from parallelism. An angle a enclosed between two tangents 128 and 129 of any two trailing edge segments in FIG. 3, or between two trailing edge segments, for instance trailing edge segment 125 and 127 in FIG. 4, may be larger than 90, for instance 93 or larger. This embodiment has shown particularly beneficial in a case when the vortex generating device is intended to be manufactured by casting. Due to the fact that the minimum angle between any two trailing edge segments, or tangents thereof, respectively, is always an obtuse angle and is never an acute angle, undercuts are avoided, and, for the more specific instance, always a proper draft angle for the removal of the component from a casting mold is provided. However, if other manufacturing methods are chosen, such as additive manufacturing methods, for instance those known to the person skilled in the art as electron beam melting (EBM) or selective laser melting (SLM), also acute angles and related undercuts may be provided.
(17) FIG. 5 depicts an embodiment wherein a multitude of vortex generating devices 1 of the kind herein disclosed are applied as fuel injection devices for a subsequent combustion stage of a sequential combustion gas turbine engine. A view is shown onto a part of a cross section of the gas turbine engine. An annular hot gas duct 103 is provided between an inner casing 101 and an outer casing 102 of the gas turbine engine. View direction is upstream. Hot gas duct 103 is arranged and configured to receive still oxygen-rich flue gas from a precedent combustion stage, and to discharge the flow into a subsequent combustor. A multitude of vortex generating devices 1 are circumferentially distributed in annular hot gas duct 103. At the trailing edge of each vortex generating device fuel discharge means are provided. At the trailing edge of each vortex generating device a liquid fuel discharge nozzle 51 is provided at the inflection point, while a multitude of gas fuel discharge openings 52 are provided between the inflection point and the spanwise ends. The skilled person will readily appreciate how for instance shielding air openings may be arranged at the trailing edge, and that the vortex generating devices may be equipped with an appropriate cooling arrangement. It is noted that fuel discharge nozzle 51 may, in a manner known from the art, be a combined liquid fuel/gas fuel discharge nozzle, wherein a liquid fuel discharge nozzle is provided concentrically, with a gaseous fuel discharge opening being provided on an outer radius. A shielding fluid discharge opening may be provided radially outside the concentrically arranged liquid fuel discharge nozzle and gas fuel discharge opening. In said case, dedicated gas fuel discharge openings 52 may or may not be provided in addition to the concentric gas fuel discharge opening of nozzle 51.
(18) It is noted that while the trailing edges of the fuel injection devices are shown to be undulating in phase, that is, all have identically curved segments in a radially inner part of the annular duct and in the radially outer part of the annular duct, they may also be provided in various out of phase arrangements, as is disclosed in EP 3 023 696. The respective disclosure of EP 3 023 696 is disclosed herein by reference.
(19) The fuel, or any other fluid to be discharged on the surface of the body 10, and more in particular at trailing edge 12, will generally be provided to the interior of the body 10 through ducts running parallel to the spanwidth direction s, or, with reference to the depiction of FIG. 5, either radially outwardly from inner casing 101 or radially inwardly from outer casing 102. In certain instances, those internal ducts may have a comparatively small flow cross-section, such that the fluid flowing through the interior of the body 10 may experience a significant pressure drop over the spanwise extent of the vortex generating device. In order to achieve for instance a homogeneous distribution of fuel, but also in order to achieve a particular flow field downstream vortex generating device 1, the trailing edge may be one of contoured or non-perpendicular to the streamwise direction e when viewed in a plan view onto the body. Said is illustrated in FIGS. 6 through 9.
(20) With reference to FIG. 6, a vortex generating device 1 is shown wherein the trailing edge 12 is tipped, such that the chord length of the body is smaller at the spanwise ends than at a location between the spanwise ends.
(21) With reference to FIG. 7, a vortex generating device 1 is shown wherein the trailing edge is recessed, such that the chord length of the body is larger at the spanwise ends than at locations between the spanwise ends.
(22) FIG. 8 shows a sectional view of an embodiment similar to that shown in FIG. 5, wherein the trailing edge of a vortex generating device 1 is slanted such that the chord length is smaller adjacent the outer casing 102 than adjacent the inner casing 101.
(23) FIG. 9 shows a cross-sectional view of an embodiment similar to that shown in FIG. 5, wherein the trailing edge of a vortex generating device 1 is slanted such that the chord length is smaller adjacent the inner casing 101 than adjacent the outer casing 102.
(24) It is apparent that with the embodiments shown in FIGS. 6 through 9 it is possible to adjust the pressure drop of the outer flow around the vortex generating device from the leading edge 11 to the trailing edge 12 as dependent on the spanwise position.
(25) While the subject matter of the disclosure has been explained by means of exemplary embodiments, it is understood that these are in no way intended to limit the scope of the claimed invention. It will be appreciated that the claims cover embodiments not explicitly shown or disclosed herein, and embodiments deviating from those disclosed in the exemplary modes of carrying out the teaching of the present disclosure will still be covered by the claims.
LIST OF REFERENCE NUMERALS
(26) 1 vortex generating device 10 body 11 leading edge 12 trailing edge 13 camber line 14 profile cross section 15 profile cross section 16 surface of body 17 surface of body 20 nominal incident flow direction 51 liquid fuel discharge nozzle 52 gas fuel discharge opening 101 inner casing 102 outer casing 103 hot gas duct 121 spanwise end of trailing edge 122 spanwise end of trailing edge 123 section of trailing edge 124 section of trailing edge 125 segment of trailing edge; straight outer segment 126 segment of trailing edge; straight outer segment 127 segment of trailing edge; straight central segment 128 tangent to trailing edge segment 129 tangent to trailing edge segment 131 imaginary trailing edge diagonal 141 imaginary trailing edge mean line 151 crossing point of trailing edge with imaginary trailing edge diagonal; diagonal crossing point a angle enclosed by two trailing edge segments, of tangents thereto h distance of training edge from trailing edge mean line l streamwise direction s spanwise direction
