Injection element

The invention relates to an injection element having an inner element with a first outlet opening and an outer element. The outer element includes at least one second outlet opening structured and arranged for receiving and injecting fuel in a combustion space, and arranged coaxially to the first outlet opening. The outer element further includes third outlet openings composed of bores structured and arranged for forming a cooling liquid film layer, wherein the bores are arranged coaxially to the first outlet opening and the at least one second outlet opening.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage Application of International Application No. PCT/DE2004/002430 filed Nov. 3, 2004, which published as WO 2005/049998 A1 on Jun. 2, 2005, the disclosure of which is expressly incorporated by reference herein in its entirety. Further, the present application claims priority under 35 U.S.C. §119 and §365 of German Application No. 103 53 423.7 filed Nov. 15, 2003.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an injection element, in particular for a rocket drive, with an inner element with a first outlet opening and an outer element arranged coaxially thereto with at least one second outlet opening arranged coaxially to the first outlet opening for receiving and injecting fuel in a combustion space.

2. Background Description

Injection elements are used in a rocket drive for the mixture preparation and for ensuring an optimal combustion in a combustion space of the rocket drive.

An injection element in coaxial construction for operation with two hypergolically reacting fuels is known, e.g., from DE 43 05 154 C1. With this injection element, the combustion fuel flow fed separately to the combustion chamber is divided by means of a flow divider provided with bores, into several individual flows distributed over the circumference of the feed channel. This is to render possible a stable combustion without relevant pressure fluctuations.

Furthermore, an injection element is known from DE 101 30 355 A1 in which a fuel flow fed to a combustion chamber is divided and the two partial flows thus produced are injected into the combustion chamber in a separated manner. The injection hereby occurs in the form of two hollow cone flows coaxial to one another. An optimal droplet preparation with different droplet size in the two hollow cone flows can thus be achieved, which render possible special combustion zones with different combustion behavior or a gradual combustion of the fuel.

DE 195 15 879 C1 describes an injection element in bicoaxial construction, i.e., the injection element comprises an inner element with a first outlet opening to form a conical oxidant jet and an outer element arranged coaxially thereto with further second outlet openings in the form of passage channels to form fuel jets.

In many cases it is necessary to create a zone for cooling an area of the combustion chamber close to the wall. In order to achieve this, in part the integration is resorted to of additional injection elements embodied especially for this purpose. These can be on the one hand elements with liquid swirl and on the other hand also simple elements with bores.

SUMMARY OF THE INVENTION

The aim of the present invention is now to create an injection element, in particular for a rocket drive, which at the same time renders possible the formation of a cooling liquid film layer for the injection of fuel in a combustion space.

According to the invention, the injection element includes an outer element having third outlet openings in the form of bores for forming a cooling liquid film layer. The bores are arranged coaxially to the first and second outlet openings. The invention is also directed to an injection element having an inner element with third outlet openings in the form of bores for forming a cooling liquid film layer. The bores are arranged coaxially to the first and second outlet openings.

One important concept of the invention lies in providing bores in an inner or an outer element of the injection element, which bores are used to separate the fuel necessary for a cooling liquid film layer. The advantage of such an injection element is that elements already present of conventional injection elements are used to create a fuel-rich or oxidizer-rich zone. Furthermore, only one element is required to form a cooling film area, and additional elements are not necessary. In addition, there is the possibility of creating two zones in the combustion space with the injection element according to the invention. Furthermore, a gradual reaction (combustion) can be achieved with the invention. Finally, the invention is suitable for use in a wide operating range with regard to a mixing ratio of fuel.

The invention now relates to an injection element, in particular for a rocket drive, with an inner element with a first outlet opening and an outer element arranged coaxially thereto with at least one second outlet opening arranged coaxially to the first outlet opening for receiving and injecting fuel in a combustion space. According to the invention, the outer element has in addition third outlet openings in the form of bores for forming a cooling liquid film layer, which bores are arranged coaxially to the first and second outlet openings.

In particular, the outer element can have a swirler space for impressing a swirl in the fed fuel flow, in which the bores are provided. In this case, fuel for forming the cooling liquid film layer is split off via the bores in the swirler space. Swirlers are known, e.g., from DE 101 30 355 A1 already mentioned at the outset and are also referred to there as a swirl insert.

Preferably the bores are provided in a tapering area of the swirler space. The bores can thus receive fuel particularly efficiently.

The bores can be arranged in the outer element such that the influence of the cooling liquid film layer formed through the bores on the fuel injecting into the combustion space is as slight as possible. In other words, the bores can be aligned such that the cooling liquid film layer and the fuel injecting into the combustion space just after entry into the combustion space do not touch one another or mix.

The bores can change over into an annular gap to generate a swirl. In this case a cooling liquid film layer is formed with a swirl, which can have an advantageous effect on the formation of an optimal mixture in the combustion space.

The invention further relates to an injection element, in particular for a rocket drive, with an inner element with a first outlet opening and an outer element arranged coaxially thereto with at least one second outlet opening arranged coaxially to the first outlet opening for receiving and injecting fuel into a combustion space, in which according to the invention the inner element has third outlet openings in the form of bores for forming a cooling liquid film layer, which bores are arranged coaxially to the first and second outlet openings.

With this type of injection element, a partial premixing takes place that is of major importance for an optimal combustion, particularly in the case of elements with hollow cones of injected fuel that do not overlap.

With the two types of injection elements explained above, according to the invention the bores can be distributed in particularly uniformly over the entire circumference of the outer or of the inner element. A conical cooling liquid film is thus created. This is expedient in particular with drives with only one injection element (single-element chambers). With such drives the conical liquid film then serves to cool the inner wall of the combustion space and avoids an enrichment of excess fuel during the phase of the ignition in the area of the combustion space close to the wall. This is very important, particularly with short-term operations, and greatly reduces the danger of the deposit of too much residue such as, e.g., soot on the inner wall of the combustion chamber. As already mentioned, a two-zone combustion can be created above all by only one injection element.

In particular when several injection elements are used, it is more advantageous if the bores are distributed in particular uniformly over only a part of the circumference of the outer or inner element. Preferably the bores should then be arranged in the part of the circumference that lies adjacent to the inner wall of the combustion space so that the liquid film layer exiting from the bores sprays in the direction of the inner wall.

With a preferred embodiment with simple bores for feeding a component, the bores are preferably aligned such that fuel jets exiting from them are mixed with the component jets leaving the components feed bores. A premixing of fuel and component thus occurs through which a droplet formation already takes place early. This has an advantageous effect in the main mixing with a hollow cone of a swirler element.

Finally the invention relates to the use in a rocket engine that has a combustion space. The rocket engine is characterized in that it has at least one injection element according to the invention.

In particular the at least one injection element according to the invention is arranged with the rocket engine such that the cooling liquid film layer exiting from it is directed at least in part towards the combustion space inner wall.

The same and functionally the same elements can be provided with the same reference numbers below.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1Ashows in cross-sectional representation an injection element10with an inner element12and an outer element14. Inner and outer element12or14are arranged coaxially to one another. Both elements receive fuel under high pressure, which fuel is injected through each element respectively in the form of a hollow cone into a combustion space (not shown) of a rocket drive. The fuel is injected via feed bores60and62into the inner or outer element12or14. Moreover, the outer element14has a swirler space18in order to give the fuel a swirl.

FIG. 2Ashows the injection element10fromFIG. 1Ain a perspective cross-sectional representation. Here the front face30of the injection element10can be seen clearly from which the fuel exits and is injected into the combustion space.

The outer element14has several bores16in its outer wall, which bores begin in the tapering area20of the swirler space18and end in the front face30facing the combustion space. The bores16receive the fuel located in the swirler space18and feed the received fuel to the combustion space in the form of another hollow cone. The bores16are aligned such that the fuel sprays into the combustion space in the form of a hollow cone that opens in the direction of the inner wall of the combustion space in order to cool the inner wall.

FIG. 1Bshows another injection element11in cross section, which element is essentially similar to the injection element10ofFIG. 1A, in which, however, inclined bores24are provided in the outer element15, which bores end in an annular gap22of the outer element15. With this exemplary embodiment the fuel is injected via the annular gap22with a swirl into the combustion space. To this end the bores24are inclined in two levels.FIG. 2Bshows this exemplary embodiment in a perspective cross-sectional view. Through the inclination of the bores24, the fuel is already injected into the annular gap22with a swirl.

FIGS. 2C and 2Dshow the front faces30and32of the two exemplary embodiments of the injection elements10or11shown inFIG. 1A,2A or1B,2B. With the first exemplary embodiment10inFIG. 2Ca total of eight bores16are uniformly distributed over the circumference of the front face30, i.e., the bores16are equally distanced from one another. With the second exemplary embodiment11inFIG. 2Dfour bores16distributed uniformly over the circumference of the front face32discharge into the annular gap22. Both injection elements10and11are suitable as single elements for a combustion space or a combustion chamber.

FIG. 3shows the arrangement of several injection elements28and34in a combustion chamber of a rocket engine. The injection elements labeled34are conventional injection elements that serve only to inject fuel into the combustion space. Although the injection elements28according to the invention likewise serve to inject fuel, at the same time they serve to form a liquid film layer cooling the combustion space inner wall26. They differ from the exemplary embodiments10and11explained above in that bores16are provided only on the part of the circumference of the front face of these injection elements28that is arranged directly adjacent to the combustion space inner wall26, i.e., in the area of the circumference of the front face close to the wall. Fuel is thus sprayed from the bores16in the direction of the combustion space inner wall in order to cool it. This exemplary embodiment is suitable for engines with several injection elements as shown. Inhomogeneities can be influenced or correspondingly oriented through a corresponding remaining run length of the swirler space.

FIG. 4shows in cross section another exemplary embodiment of an injection element36that has an inner element38and an outer element40arranged coaxially thereto. In this exemplary embodiment bores42are provided in the inner element38, which bores end at the front face43. The bores42are aligned such that the fuel thus split off from the inner element38mixes with the fuel injected into the combustion space through the outer element40(fuel hollow cone46). Through this a partial premixing takes place which has an advantageous effect in particular with elements that form non-overlapping fuel hollow cones44and46as in the exemplary embodiment shown.

FIGS. 5 and 6finally show injection elements48and50that are provided with component feeds, more precisely with bores52or54for feeding a component.FIG. 5shows an “unlike triplet” in which three liquid jets intersect (at reference number56). In contrastFIG. 6shows an “unlike doublet” in which two liquid jets intersect (at reference number58). Through the “intersection” of the jets a pre-mixing occurs and thus a droplet formation, which has a favorable effect on the main mixing with the hollow cone of the swirler element.

LIST OF REFERENCE NUMBERS