EP0807213B1 - Flow-guiding body for gas turbine combustion chambers - Google Patents

Abstract

A flow-guiding body is designed as a pointed, substantially conical moulded shell (1). The projection of its base surface is formed by a straight line (3a) and by a curve (3b) that interconnects the ends of the straight line. The curve (3b) forms no significant angles. The moulded shell (1) faces with its point the fluid flow that hits its outer side and may be used as a mixing element for gaseous fuel and air, as an air sprayer with flame-holder, as a mixing element for admixed air in combustion chambers, as a swirling element or as a shell-shaped air sprayer combined with a fuel film generator or a fuel pressure spraying nozzle.

Description

The invention relates to a flow guide body on a gas turbine combustion chamber for swirling an impinging air flow, consisting of at least one tapered molded shell of essentially conical shape, the base surface projection of which is formed by at least one straight line and any curve connecting the end points of the straight line, wherein the tip of the molded shell essentially faces the air flow hitting the outside.
A comparable flow guide body is known from EP-A-0 063 729 as a device for inverting and mixing flowing substances.

So-called gas turbine combustion chambers, in particular for aircraft engines. Air atomizers known which have two or more coaxial ring channels, through which the air mass flows conveyed by the compressor with different Stream swirl. It became known in this context already a mixture with fuel; there are two air channels separated by a tapered circular ring on which a fuel film is applied. This is from the air masses to the end edge of the Driven circular ring and atomized there. In the vicinity of the atomizing edge has the fuel drop spray trailing character, what a poor homogeneity of the resulting air-fuel mixture results.

Furthermore, there is a flow guide body with a tapered molded shell in connection with a fuel supply system for a combustion chamber EP-A-0 619 456 and in connection with a premix burner from the EP-A-0 619 457 known.

It is also known on gas turbines, the admixing air for the different Burning zones of a combustion chamber through pressed or drilled holes in to feed the combustion chamber wall. This often happens in such a way that the individual air jets through different holes in the combustion chamber wall arrive, meet at a stagnation point and there locally for high turbulence to care. The blown air jets inside the Combustion chamber from the hot gas located there, however, in the manner of a massive one Flows around the rod, so that in the area of the meeting of Hot gas and admixing air do not result in optimal air mixing. Only in Interface area between the admixed air jet and the hot gas occurs a mix up. This so-called hot gas slip through the hole cross-section a combustion chamber is known to be relatively high.

To improve the mixing processes of gases in or on gas turbine combustion chambers so-called delta wings have also become known. For this purpose, reference is made, for example, to EP 0 623 786 A1 or to US 3,974,646. Delta wings of this type are sharp-edged Bodies that have an impinging flow field in two each a vortex axis divides possessing partial flows in such a way that the vortex axes run convergent. The mixing processes that can be achieved hereby can be convergent Do not fully satisfy vortex formation.

The object of the invention is therefore to demonstrate measures by means of which mixing processes of gases in gas turbine combustion chambers can be improved. In particular, non-convergent and preferably divergent vortex axes or vortex braids are to be generated downstream of the flow guide body.
To solve this problem, the characterizing features of independent claims 1 or 2 are provided, advantageous training and further developments are the content of the subclaims.

Fig. 1

zur Erläuterung der Grundlagen eine Perspektivdarstellung lediglich eines Strömungsleitkörpers (Formschale) sowie einen auftreffenden Fluidstrom,

Fig. 2

das von der Formschale induzierte Strömungs-Wirbelfeld in einem Schalenschnitt senkrecht zur Hauptstromrichtung,

Fig. 3

eine Seitenansicht der Formschale bzw. des Strömungsleitkörpers, aus der der Anstellwinkel, der Öffnungswinkel sowie der Verlauf einzelner Stromlinien hervorgeht,

Fig. 4

einen Blick von oben auf die Formschale bzw. den Strömungsleitkörper, wobei schematisch das Strömungsfeld eines aufgeplatzten Wirbelpaares dargestellt ist, während

Fig. 5

immer noch zur Erläuterung der Grundlagen einen sog. Doppelschalenzerstäuber, im wesentlichen bestehend aus zwei Strömungsleitkörpern, zeigt.

The invention is explained in more detail with reference to preferred exemplary embodiments. In detail shows

Fig. 1

to explain the basics, a perspective view of only one flow guide body (molded shell) and an impinging fluid flow,

Fig. 2

the flow vortex field induced by the molded shell in a shell section perpendicular to the main flow direction,

Fig. 3

2 shows a side view of the molded shell or of the flow guide body, from which the angle of attack, the opening angle and the course of individual streamlines are evident,

Fig. 4

a view from above of the molded shell or the flow guide body, the flow field of a split vortex pair is shown schematically, while

Fig. 5

still shows a so-called double-shell atomizer, consisting essentially of two flow guide bodies, to explain the basics.

Fig. 6

die Seitenansicht einer derartigen Formschale im Bereich der Zumisch-Luftlöcher einer Gasturbinen-Brennkammerwand, und

Fig. 7

die Ansicht X aus Fig. 6 zeigt.

A first application according to the invention for such a flow guide on a gas turbine combustion chamber is shown in FIGS. 6 and 7, wherein

Fig. 6

the side view of such a molded shell in the area of the admixing air holes of a gas turbine combustion chamber wall, and

Fig. 7

the view X from Fig. 6 shows.

Fig. 8

eine Anwendung eines erfindungsgemäßen Strömungsleitkörpers mit einem sog. Kraftstorf-Filmleger in einem Seitenschnitt. und

Fig. 9

die Ansicht Y aus Fig. 8, sowie

Fig. 10

die Ansicht Z aus Fig. 8 zeigt.

Fig. 11

zeigt eine andere Ausgestaltung mit einem Kraftstoff-Filmleger,

Fig. 12

den Schnitt A-A aus Fig. 11,

Fig. 13

zeigt noch eine weitere Variante eines Doppelschalen-Zerstäubers mit einem Kraftstoff-Filmleger, sowie

Fig. 14

den Schnitt B-B aus Fig. 13.

Further applications for such a flow guide on a gas turbine combustion chamber are shown in FIGS. 8-14, wherein

Fig. 8

an application of a flow guide body according to the invention with a so-called Kraftstorf film layer in a side section. and

Fig. 9

the view Y from Fig. 8, as well

Fig. 10

the view Z from FIG. 8 shows.

Fig. 11

shows another embodiment with a fuel film layer,

Fig. 12

the section AA from FIG. 11,

Fig. 13

shows yet another variant of a double-shell atomizer with a fuel film layer, as well

Fig. 14

the section BB from FIG. 13.

The so-called flow guide is in all the figures designated with the reference number 1. It is always a Shaped shell 1 of substantially conical shape. The projected Base 2 of this molded shell 1, the interior of which is hollow, is made from a straight line 3a as well as any one, the end points of the straight line connecting curve 3b. The molded shell 1 is formed by the Shell surface, which connects the curve 3b with the tip 4 of the molded shell 1. However, those running from tip 4 to curve 3b must Rays not necessarily Be straight, but can even curves represent. The shape of this molded shell is the respective one Freely selectable requirements accordingly, d. H. in A series of tests can be used for the respective application this flow line body according to the invention the most suitable form of curve 3b and each most suitable value for the so-called opening angle α des be determined by the molded shell 1 cone. Best results in terms of what is emerging Flow field downstream of the flow guide 1 were achieved when curve 3b has no significant corner points owns, d. H. the surface of the flow guide With the exception of the marginal edges, 1 has no other sharp edges. The one already quoted through the opening angle resulting from the design α is shown explicitly in FIG. 3.

The so-called angle of attack β can also be seen in FIG. 3, around that defined by the tip 4 and the straight line 3a Level 5 of the molded shell 1 in relation to the flow direction of the fluid flow is inclined. The one on the Flow guide or the shell 1 striking Fluid flow is represented by the flow vector 6. As can be seen, the molded shell 1 from the fluid flow 6 flowed on its convex side, whereby form the streamlines 7 outlined in FIGS. 1, 3.

This forms on the concave side of the molded shell 1 in Fig. 2 in a section perpendicular to the main flow direction of the fluid flow 6 shown vortex field, which has two counter-rotating pegs 8. Because of the design, curve 3b in particular runs these two vortex braids 8 downstream of the flow guide 1 apart, d. H. they diverge. In this respect differs this flow guide body 1 essential from a known delta wing, the converging Swirl braids created.

The circulation of the pegs 8 is from Angle of attack depends on β. With a sufficiently high swirl the pegs 8 burst open downstream of the molded shell 1, as shown in Fig. 4. It forms a recirculation zone which has an inner interface 9a to the central main flow of fluid. Further the fluid in rotation has one outer interface 9b to the surrounding main flow fluid, which only displaces under the curvature of its streamlines becomes.

A preferred application for an inventive Flow guide body shows Fig. 5. Here are each other adjacent, but spaced apart, two molded shells 1 arranged by a broken open Housing 10 are surrounded. Each of the two molded shells 1 is the angle of attack β relative to the horizontal, which is equal to the direction of flow of the fluid stream be employed in such a way that levels 5 of these Shells 1, which were defined in Fig. 3, between enclose the angle 2 β. This one shown in Fig. 5 So-called double-shell atomizer, which is essentially from two flow guide bodies 1 according to the invention is an air atomizer with a flame holder, where liquid fuel makes sense on the convex Side of the two molded shells 1 is applied. The Current forms on the back of the as desired Shells 1, the fluid flow between them Shells 1 by that described by the angle 2β Angular segment essentially left and right the line of symmetry of the molded shells. In this case, deviating from the arrangement shown both shells 1 also have a common tip 4.

Otherwise, gaseous or solid fuels can also be used also on the convex sides or outer sides of the Shells 1 are applied, then the one shown acts Arrangement as a mixer with flame holder. Always there a stabilization of the flame through the connection 4 illustrated recirculation zone within the split vertebrae (see reference number 8) reached.

In addition, the eddy current field of the molded shell 1 or molded shells 1 perpendicular to a second main stream is quick, for example Air admixture can be achieved in gas turbine combustion chambers. This second main stream represents the fuel gas and is sucked into the recirculation zone of the vortex braids 8. The fuel gas mixes at the interfaces 9a, 9b (see FIG. 4) with the fresh gas. How about it a molded shell 1 according to the invention on the combustion chamber wall a gas turbine can be arranged to the admixing air optimal with the fuel gas inside the combustion chamber 6, 7 show how to mix.

6, 7, the molded shell is again with the reference number 1 denotes while the combustion chamber wall Reference number 11 carries. Inside of the combustion chamber wall 11 limited combustion chamber 12, the fuel gas flows according to Arrow direction 13. This fuel gas stream 13 should be like known admixture air can be added. The admixed air flow 6 as the one hitting a molded shell 1 Fluid flow outside of the combustion chamber 12 along the Combustion chamber wall 11 brought up and can Opening 14 in the combustion chamber wall 11 in the combustion chamber 12 occur. In order to achieve the desired flow of the To achieve admixture air flow 6 is the molded shell 1 surrounded by a scoop 15, which is part of the incoming Mixing air flow 6 intercepts and in the direction of Breakthrough 14 redirects. This is the domed scoop 15 arranged on the outside of the combustion chamber wall 11 in such a way that the opening 14 is included.

The purpose of this arrangement is as follows: known prior art the admixture of admixture air often happens so that two or more Air jets hit at a stagnation point and there turbulence generate, causing a strong hot gas slip between the air jets are created in an inventive Arrangement the admixing air swirls. The the disadvantage of the known prior art, that the air jets in the stagnation point area in air bubbles split up, which is also transported by the hot gas flow and mix slowly with one another Shaped shell according to the invention, which acts as a vortex generator works, avoided. As already explained, namely here too, with this molded shell 1, vortex braids 8 are produced, which burst at a sufficiently high swirl, which 6 with the recirculation zone 16 trained by the admixture air 17th is surrounded. The improvement of the mixing effect compared the known prior art is thereby by the following Effects achieved: The cold admixing air 17 forms with the Fuel gas stream 13 again has an outer interface 9b. There the admixing air 17 is strongly swirled and compared to that Fuel gas 13 has a high density, it comes from centrifugal and buoyancy forces in the area of this interface 9b to a rapid and intensive rearrangement of both Air masses that lead to fine-grained turbulence and rapid mixing to lead. The surface of the interface 9b is around many times larger than that at the previous status technology-forming surface between hot gas and admixing air. The hot gas slip through the admixing level thereby greatly reduced.

Another application for an inventive Shaped shell 1 or a flow guide body according to the invention is shown in Figs. 8-10. Here too is the molded shell 1 in the flow path of two fluid flows, namely an air flow 6 and a fuel flow 20 arranged and acts as a so-called shell air atomizer for a fuel film layer. Like FIGS. 8, 9 show, the molded shell 1 is again from one surrounded in the form of a hood 15 in which the fuel film layer 21 is arranged. The fuel film layer 21 has a fuel channel 22 which in one Flat funnel 23 ends. As in the previous application examples also the shell air atomizer arrangement shown flowed against by the fluid stream 6.

It is for the function of the fuel film layer 21 important that this, as shown in Fig. 9, in the axis of symmetry the molded shell 1 is. Furthermore, it is it is important that the opening or the flat funnel 23 of the film layer 21 at a short distance from the surface the mold shell 1 is located, as shown in Fig. 8 is. This ensures that the escaping fuel flow 20 immediately after leaving the filmmaker 21 without atomizing onto the surface / contour of the molded shell 1 is redirected. This can provide a desired fuel distribution can be set on the mold shell 1. FIG. 10 shows the view Z from FIG. 8 of the fuel film layer 21. The fuel channel 22 can be seen as well as the flat funnel 23. The outer contour makes sense of the film layer 21 as can be seen aerodynamically shaped.

Instead of a fuel film layer, one can or several fuel pressure atomizing nozzles with any Spray nozzle characteristics in connection with an inventive Shaped shell 1 (flow guide body) arranged to be a cheap air-fuel mixture to achieve. It also uses a pressure atomizer nozzle analogous to the film layers fuel on the convex Side of the mold shell 1 applied.

Further embodiments for one of two molded shells 1 existing double-shell atomizer with one Fuel film layer 21 - alternatively, pressure atomizing nozzles be provided - show FIGS. 11, 13, sections of which are shown in FIGS. 12, 14 are. 11 shows a double-sided load Double-shell atomizer with two molded shells, similar Fig. 5. In a suitable film layer 21, the Fuel on two channels 22 (here without flat funnel 23) divided. But it is also possible to use the double-bowl atomizer to act only on one side, like this 12, 14 show.

The flow guide body 1 according to the invention or the one according to the invention Shaped shell 1 act in the last explained Exemplary embodiments in connection with a Fuel film layer 21 as a shell air atomizer, wherein the fuel through one or more fuel channels 22 can be supplied, the fuel channels 22 and possibly in one or more Flat funnels 23 open and the atomizer or Shaped shell 1 at a short distance from the flat funnel 23 or is arranged from the mouth of the channels 22, and the film layer 21 in the plane of symmetry of the molded shell (s) 1 lies. In addition, an inventive Flow guide body or a molded shell 1 also as a vortex generator are used, which then in particular one or more arbitrarily shaped molded shells 1 as well as one or more matching scoops 15 consists. This arrangement can be used for admixing and swirling cold air in gas turbine combustors. This arrangement can be anywhere on the flame tube of any combustion chamber in any Location can be attached. Generally, these can conical shaped shell (s) 1 of the shown in Fig. 1 Be of any cross-section, the shape of the tip 4 to the base 2 of the conical section going rays do not have to be straight lines. How explained in detail, this molded shell 1 as an air atomizer used for any liquid fuel become. But it is also used as a mixing element and flame holder when using gaseous or powdered or granulated solid fuels any Kind possible. Furthermore, any number of different ones can of course also be used Gas or fluid flows mixed together become. A variety of details in particular constructive type quite different from the shown Embodiments can be designed without the Leave the content of the claims.

Claims (4)

1. Fuel-guiding body on a gas turbine combustion chamber for the swirling of an impinging air stream (6), consisting of at least one essentially conoidally tapering form shell (1) whose base projection (2) is generated by at least one straight line (3a) and by any curve (3b) connecting the end points of the straight line (3a), with the form shell (1) facing the air stream (6) applied to the outer surface essentially with its apex (4),
   characterized in that the form shell (1) is surrounded by a hood (15) and is arranged externally on the combustion chamber wall (11), so that the cold air stream (6) is added to the combustion gas stream (13) flowing in the combustion chamber (12) via an opening enclosed by the hood (15).
2. Fuel-guiding body on a gas turbine combustion chamber for the swirling of an impinging air stream (6), consisting of at least one essentially conoidally tapering form shell (1) whose base projection (2) is generated by at least one straight line (3a) and by any curve (3b) connecting the end points of the straight line (3a), with the form shell (1) facing the air stream (6) applied to the outer surface essentially with its apex (4),
   characterized in that the form shell (1) is surrounded by a hood (15) and is combined with a fuel film applicator (21) or a pressure fuel atomizer nozzle, where fuel is applied to the outside of the form shell (1), this fuel being supplied to the combustion chamber together with the air stream (6).
3. Flow-guiding body of Claim 1 or 2,
   characterized in that the plane (5) of the form shell (1) defined by the apex (4) and the straight line (3a) is inclined relative to the inflow direction of the air stream (6) (incidence angle β).
4. Flow-guiding body of one of the preceding Claims,
   characterized in that several form shells (1) are arranged in a common casing (10), the form shells (1) being adjacent to each other but at least sectionally distant from each other.

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