Injection device and method for injecting a liquid-liquid fuel combination into a combustion space

Abstract

The invention relates to an injection device for introducing a liquid-liquid fuel combination, in particular hypergolic, into a combustion space of a combustion chamber of a spacecraft, the injection device comprising an impact plate which, in operation, fuel components strike and at least one first channel with a first outlet arranged at its downstream end and at least one second channel with a second outlet arranged at its downstream end for conducting each of the fuel components and ejecting the fuel components to strike the impact plate.Defined combustion over a wider operating range can be achieved by arranging the channels with the outlets relative to each other in such a way that the fuel components come into contact with the impact plate at contact areas located at different locations, one from the other coming into contact with the impact plate, the contact area or contact areas of one of the fuel components being positioned in particular radially further outward, further from the longitudinal axis of the injection device.

Description

Title of the invention: Injection device and method for injecting a liquid-liquid fuel combination into a combustion space

[0001] The invention relates to an injection device for introducing a liquid-liquid, in particular hypergolic, fuel combination into a combustion space of a combustion chamber of a spacecraft, the injection device comprising an impact plate which fuel components strike during operation, and at least one first channel with a first outlet located at its downstream end and at least one second channel with a second outlet located at its downstream end for directing the fuel components and the respective fuel component jets to strike the impact plate. The invention also relates to a method in which a liquid-liquid, in particular hypergolic, fuel combination is injected into a combustion space of a combustion chamber of a spacecraft.

[0002] An injection device of this type is disclosed in US 3,897,008 A. In this known injection device, a first and a second fuel component of a liquid-liquid fuel combination are ejected via a first and a second channel onto an impact plate arranged at a distance from their outlet and oriented obliquely to the longitudinal axis of the injection device and conveyed via a mixing path to a combustion space for combustion. The two channels each have a cylindrical annular cross-section on the outlet side, which connects to a conical cross-section on the inlet side, which is formed on a sleeve mounted axially movable relative to the channels. The flow cross-section of the channels can be varied on the inlet side by the conical cross-sections. At the end of the impact plate downstream of the flow, towards the combustion space, there is a circumferential flange which deflects the flow.This design of the injection device can lead to unfavorable flow conditions with incomplete flow in the outlet channel. By reducing the massive flow rate via the conical surfaces of the unique adjustment element in the form of the movable sleeve at the fluid inlet into the channels, the flow rate can be reduced to such an extent that the injection is impaired. Since only the sleeve is designed to be movable, the two passages for the fluid can only be adjusted in relation to each other, which limits the adjustment of the operating point. Due to the relatively closed design due to the diverter element, overpressures can occur due to the restricted expansion space, especially when mixing substances. spontaneously igniting or hypergolic fluids, which can damage the injector and an engine equipped with it.

[0003] Another injection device is described in US application 3,790,088 A.

[0004] US application 3,372,543 A shows an injection device with a plate impact plate, the oxidizer and fuel being introduced into chambers in a swirling manner, each flowing from one side of the impact plate and arriving on a surrounding annular plate with guide plates to form the mixture.

[0005] Another injection device comprising an impact plate is described in US application 3,137,445 A.

[0006] Another injection device, in the form of a "Pintle injector" without an impact plate, is described in document KR 102 311 059 Bl.

[0007] The objective of the present invention is to develop an injection device allowing reliable operation of combustion over a wide operating range and a corresponding method.

[0008] The objective is fulfilled by the injection device and by the method whose characteristics are described in the following.

[0009] In the injection device, it is provided that the channels with the outlets, the channels being in particular conical with respect to a longitudinal axis of the injection device, are arranged with respect to each other in such a way that the fuel components strike the impact plate at contact zones (location at which each of the fuel components first strikes the impact plate) located at different locations. In particular, the contact zone(s) of one of the fuel components may be positioned radially further outwards, at a greater distance from the longitudinal axis of the injection device.

[0010] The contact zones may have one or more point and / or linear shapes.

[0011] In particular, the channels with the outputs are arranged at a distance from each other. others such that the fuel components at least do not substantially interact with each other until they strike the impact plate and / or flow in liquid layers spaced apart from each other. The liquid layers may, for example, flow parallel to each other or the radially outer liquid layer may be oriented more obliquely (with a larger angle α) than the radially inner liquid layer to reduce the impact force on the contact area. The flow is preferably rotation-free.

[0012] For the design, preliminary experimental tests and / or numerical (computer-aided) simulations can be carried out with the fuels to be used and / or at the relevant operating points.

[0013] In order to supply the channels with fuel components, a fuel supply system may be provided with separate distribution chambers for the fuel components and assigned to each of the channels.

[0014] By the impact of the fuel components at different locations (contact zones), it can be defined how the first contact of the fuel components with each other and / or a mixing process will take place on the impact plate and / or after the flow of the impact plate. In particular with hypergolic fuels (which ignite spontaneously when they come into contact with each other), it can be defined how the ignition process will take place taking into account the ignition delay time, which is essential for ignition at a defined ignition location. In this way, a stable combustion process with an at least essentially defined ignition location and / or local composition can advantageously be achieved over a wide operating range.

[0015] The channels are aligned with the contact zones which are opposite the space which separates them. The contact zone(s) of the internal fluid are preferably located in the radially internal third of the impact plate, the contact zone(s) of the external fluid are located next to it, for example in the radially central and / or external third of the impact plate.

[0016] In a safety-advantageous design mode, provision is made for a space to be provided between at least one of the outlets and the impact plate, within which, in operation, at least the fuel component flowing through one of the channels, in particular the outer channel (radially outer fuel component), forms a free or partially free liquid layer. For example, a free or partially free liquid layer can be formed for each fuel component. A partially free layer is formed when, with a suitable design of the injection device, the liquid layer is in contact with a wall on one side, preferably the radially inner side, but not on the other side, preferably the outer side.Alternatively, the gap to the radially inner channel may be so small that the radially inner fuel component forms a fuel layer on the impact plate immediately after its exit without forming a liquid layer. With a larger gap for the formation of the at least one liquid layer, upon confluence of the two fuel components, even in the event of possible ignition on the impact plate, the energy released upon ignition may be directed outward into the combustion space and not through the channel(s) into the interior of the injection system. This could lead to damage or destruction of the injection device.

[0017] In a configuration for forming a free liquid layer, an outlet is by definition located at the upstream end of the free liquid layer; in a configuration for form a partially free liquid layer, the outlet is at the upstream end of the partially free liquid layer and in a configuration without liquid layer formation, the outlet is at the downstream end of the respective channel.

[0018] The size of the gap corresponding to the distances between the outlets and the impact plate may be different depending on the outlets and / or variable if parts of the injection device are axially movable. The size of the gap is preferably designed to be small enough that during operation (at any point of operation), the multiple liquid layers of the fuel components used that may be present do not come into contact with each other before striking the impact plate, due to instabilities such as for example perforations or nebulization. In addition, the size of the gap is designed to be large enough that during operation (at any point of operation), the outlets and / or possibly axially movable parts of the injection device leave sufficient space for the formation of the fluid layer on the impact plate.

[0019] The flow section of the channels is also designed in such a way that the stable liquid layer is formed with the fuel components used, the flow speeds in particular being able to be kept relatively low (for example less than 100 m / s).

[0020] The liquid layers flow, for example, conically around the entire circumference, directed axially-radially inwards at a constant angle α, as a result of which the contact zone is formed for each liquid layer by a contact ring around the entire circumference. The liquid layers can also be formed in a jet and / or have several jets.

[0021] Contact or confluence of the fuel components at a defined location is promoted when the channels with the outlets are designed and / or spaced from each other in such a way that the fuel components, in particular the liquid layers, do not at least substantially interact with each other before contacting the impact plate. In particular, the contact areas do not overlap.

[0022] An angle α between the channels (with respect to the central axes of the channels) and / or between the liquid layers and the impact plate is preferably between 90° and 180°, more preferably between 90° and 145° or between 90° and a maximum angle of "180°-|3", where [3 corresponds to an angle of inclination between the longitudinal axis (and / or a line parallel thereto) and the impact plate. The angle α therefore essentially corresponds to an angle clamped between the liquid layer(s) (in the direction of flow) and the fuel components on the impact plate (in the direction of flow). During operation, the choice of these angles causes, after impact of the liquid layers on the impact plate, a flow impulse directed radially outwards.

[0023] In a preferred embodiment, the impact plate and / or the channels are / are arranged coaxially with each other and are rotationally symmetrical about the longitudinal axis. This advantageously provides a high degree of symmetry in the supplied fuel components, combined with mixing and combustion of the fuel components that is as uniform as possible and utilizes the combustion space over a wide operating range.

[0024] The channels are preferably designed as coaxial, in particular conical, annular slots, forming at least one radially inner channel and at least one radially outer channel, the annular slots being, for example, oriented radially inwards in the direction of flow, or parallel to each other or with different angles. A radially outwards orientation so that the fuel components strike the impact plate would also be possible. The heights of the slots (distance between the walls of the annular slot) are preferably constant around the circumference. This arrangement of the annular slots allows the fuel components to be distributed uniformly all around on the impact plate, as well as advantageous control of the fuel flow rates, for example by varying the heights of the annular slots and / or the pressure within the fuel supply system..

[0025] In a preferred embodiment, the impact plate extends, for example conically, around the longitudinal axis and is inclined radially outwards in the direction of flow, with an inclination angle (|3) (constant) between the longitudinal axis and the surface profile (with respect to the axial-radial directional component of the impact plate) between 0° and 90°, preferably between 30° and 75°, for example 45° or 60°. The surface of the impact plate extends from a radially inner edge to a radially outer edge. Due to this orientation of the impact plate, the thickness of the layer formed by the fuel components flowing over the plate decreases outwards, which has a positive effect on the mixing and / or ignition of the fuel components.The inclination angle [3 is preferably designed in such a way that the fuel components are ignited radially and preferably also axially away from the injection device and / or the combustion space wall. On the other hand, the axial directional component should be so small that the combustion space length can be designed to be as short as possible in favor of a compact design of the combustion chamber.

[0026] Preferably, the axial-radial size of the impact plate (distance from the outer edge) and / or the position of the contact areas on the impact plate (by appropriate positioning of the channels and / or outlets relative to the impact plate) is (are) designed in such a way that during operation, an ignition of the fuel components occurs in the combustion space after they have flowed out of the impact plate. After flow out of the impact plate, a free fluid layer is formed within which the fuel components that have been brought together continue to mix. The spray angle of the fluid layer, corresponding to the inclination angle of the impact plate, is advantageously constant at each operating point due to the deflection in the axial-radial direction by the impact plate (without imparting rotation by fluid guiding elements). The fluid layer can become unstable due to the formation of perforations and / or nebulization for example, which is however not necessary, especially when using a hypergolic fuel combination.Ignition in the combustion chamber creates a kind of "semi-external" mixing injection device, the fuel components being mixed partly on the injection device (more precisely on the impact plate) and partly inside the combustion space (which in particular means that there is no deflection downstream of the impact plate, as is the case, for example, with the relatively closed design according to US application 3,897,008 A, see deflection 58 therein). The distance between the place where the fuel components merge, in particular the second external contact area, and the ignition location forms a defined mixing length, which is, for example, greater than the distance between the location of the confluence of the fuel components and the outer edge. Ignition on the impact plate is also possible.

[0027] The design, in particular the dimensioning of the impact plate, is carried out in particular taking into account the ignition delay time and / or the flow rate of the fuel mixture which is formed on the impact plate. In particular, the size of the impact plate, in particular the outer diameter, is designed relative to the walls of the combustion chamber, in particular relative to a diameter of the combustion space (which is for example cylindrical), with the outer diameter of the impact plate (defined by the outer edge) being for example between 1 / 6 and 1 / 2 of a diameter of the combustion space. The distance between the ignition point and the injection device and / or the wall of the combustion space must be large enough to avoid excessive thermal loading of the injection device and / or the wall of the combustion chamber.

[0028] In one embodiment, the impact plate may comprise a catalytically active material, in particular comprising and / or being formed from it and / or being coated with it and / or being heatable. In connection with the hydrogen peroxide, the catalytically active material may be, for example, copper. In this way, the ignition can advantageously be influenced, for example improved, and / or the ignition delay time can be shortened.

[0029] In an advantageous and relatively easy to manufacture embodiment, the injection device comprises or is formed of three parts, for example with rotational symmetry, capable of guiding a fluid, the impact plate being arranged on a first part arranged centrally (symmetrically) on the longitudinal axis. The first part is surrounded coaxially around the entire circumference, in a section which may be conical upstream of the impact plate, by a second part, which may be conical (with the same angle), and the second part is surrounded coaxially around the entire circumference by a third part, which may be conical (with the same angle). The inner annular slot is formed between the first part and the second part and the outer annular slot is formed between the second part and the third part.The conical parts can also be formed in such a way that the channels have different axial-radial inclinations, so that the channels are not parallel to each other. In particular for manufacturing reasons, there can also be several parts and / or at least one of the three functional parts can be composed of several parts. In connection with this embodiment, the positions of the contact areas, in particular of the contact rings, also remain at least substantially constant over a wide operating range.

[0030] An advantageous possibility of reducing the flow rate, in particular for the adjustment of the load point, can be obtained when the three parts are arranged to be movable relative to each other by means of an existing adjustment mechanism for adjusting a slot height of the annular slots, in particular by axial displacement of the first part and / or the second part.

[0031] In a particularly user-friendly embodiment, the adjustment mechanism is designed to be self-regulating, the gap heights of the annular gaps being adjusted using the system pressure as a driving force, the adjustment mechanism comprising in particular a suitably designed spring device, if necessary also comprising a damping device. For example, the channels can be adjusted to the required flow cross-section by moving the parts surrounding the channels apart from each other by the system pressure. This movement can be counterbalanced by spring devices which are adjusted via their spring constants in such a way that the required flow cross-section during operation and thus the corresponding mass flow rate are adjusted for the corresponding system pressure.In a space-saving embodiment, the spring devices could, for example, be at least partially introduced into the distribution spaces in contact with the fuel components. Adjustment by means of an actuator is also conceivable.

[0032] Safety and operational advantages result from the fact that at least one of the annular slots is designed to be completely closable, the volume of a distribution space (for supplying the respective channel with the respective fuel component) in communication with the at least one annular slot being designed to be able to be reduced when the annular slot is closed. When one of the annular slots is closed, it is possible to operate the injection device in monopropellant mode (e.g. with hydrogen peroxide). The reduction of the distribution space results in a lower dead volume, which provides safety advantages, particularly in relation to hypergolic fuels.

[0033] Advantageous embodiments of the method are described in relation to the injection device.

[0034] The method can also advantageously provide that the flow pulses of the fuel components are different, the flow pulse of the liquid layer, for example the radially inner one, being in particular greater than the flow pulse of the other liquid layer, for example the radially outer one. It has been shown that indefinite splashing or upward spraying when the two fuel components merge ("up-wash-formation") can be minimized in this way, in addition to the advantageous one-sided guidance of the fuel components onto the impact plate compared to a confluence of two free layers. This ratio of the flow pulses can be achieved, for example, via a higher flow velocity and / or a higher mass flow rate of the radially inner fuel component.Appropriate Weber numbers (ratio of inertial force to surface force) can be used for the design with each of the fuel components, whereby advantageous Weber numbers can first be determined experimentally and / or by means of numerical design calculations, for example. It is also possible for the radially outer layer to have the same or higher flow momentum, especially in the case of a propellant combination of propellants with adapted rheological properties (density, viscosity, surface tension), so that there is no splahing and up-wash formation.

[0035] The invention is described in more detail below with the aid of exemplary embodiments with reference to the drawings. The figures show:

[0036] [Fig-1] A schematic representation of parts of an injection device according to the invention with channels and an outwardly facing impact plate in longitudinal section

[0037] [Fig.2] A schematic representation of parts of another injection device according to the invention in longitudinal section, in a configuration for the formation of a single fluid layer

[0038] [Fig. 1] shows parts of an injection device 10 designed with rotational symmetry and oriented along a longitudinal axis L in a representation divided into two in longitudinal section. The injection device 10 serves in particular to inject a liquid-liquid fuel combination into a combustion space 16 of a combustion chamber of a spacecraft, for example a satellite and / or a launcher.

[0039] The injection device 10 is, on the inlet side of the combustion space 16 which may for example be cylindrical, arranged on a wall 18 of the combustion chamber which is itself for example cylindrical or has a front face. The wall 18 of the combustion chamber is partially indicated in [Fig.l], the exact method of connection to the injection device not being shown. The connection may be formed, for example, by means of a flange connection.

[0040] The injection device 10 is in particular part of an injection system for chemical engines using a two-component or bi-propellant system. The injection device 10 is in particular suitable for operating with hypergolic fuels (which ignite spontaneously on contact), such as monomethylhydrazine (MMH, CH6N2) as fuel and / or nitrogen peroxide (N2O4) as oxidant. The injection device 10 can also be used in a particularly advantageous manner for combinations of so-called "green" hypergolic fuels such as ionic liquids and hydrogen peroxide, forming a high-low viscosity fuel combination.

[0041] The injection device 10 comprises a first radially inner channel 26 (relative to the longitudinal axis L) with a first outlet 27 arranged at the downstream end for introducing a first fuel component 36 (hereinafter also "internal fuel component") into the combustion space 16. The inner channel 26 is preferably an annular slot 260 conical over the entire circumference designed to be rotationally symmetrical and arranged radially inwards in the flow direction, in the direction of the longitudinal axis L.

[0042] The injection device 10 further comprises a second radially outer channel 28 with a second outlet 29 arranged at the downstream end for introducing a second fuel component 38 (hereinafter also referred to as "external fuel component") into the combustion space 16. The external channel 28 is preferably an annular slot 280 conical over the entire circumference designed to be rotationally symmetrical and arranged radially inwards in the flow direction, in the direction of the longitudinal axis L.

[0043] The annular slots 260, 280 are arranged coaxially with respect to the longitudinal axis L and are, for example, parallel to each other and each have a constant slot height over the entire circumference and over their length.

[0044] Furthermore, the injection device 10 has an impact plate 34 which the fuel components 36, 38 impact when exiting the channels 26, 28 downstream of the respective outlets 27, 29 during operation, and then the fuel components 36, 38 flow from the impact plate 34 into the combustion space 16 and ignite there. The impact plate 34 is, for example, advantageously conical and arranged rotationally symmetrical about the longitudinal axis L, while being inclined radially outwards in the flow direction (radially away from the longitudinal axis L). The impact plate 34 is arranged coaxially with the channels 26, 28.

[0045] The impact plate 34 may comprise a catalytically active material or be formed therefrom or coated therewith, for example with / with copper when using hydrogen peroxide as a fuel component, whereby, in particular in the case of a hypergolic fuel combination, at least one of the fuel components 36, 38 is activated to react and an ignition 52 can be accelerated. In addition or instead of this, the impact plate 34 may in particular be designed to be electrically heatable, which improves the ignition 52 and / or reduces the ignition delay time and thus the location of the ignition 52 can be influenced (both variants are not shown here).

[0046] The impact plate 34 is designed with length 32 between a (radially) inner edge 49 and a (radially) outer edge 50 (defining the axial-radial span), also taking into account the positions of the contact zones 44, 46 (location (point(s), line(s)) of the first impact of each fuel component 36, 38 on the impact plate 34), in such a way that, during operation, an ignition, in particular hypergolic, of the fuel components takes place after their flow from the impact plate 34, out of the impact plate 34, into the combustion space 16. An injection device 10 with "semi-external mixing" is thus formed.

[0047] An angle of inclination [3 between the longitudinal axis L and the axial-radial orientation of the surface of the impact plate 34 (included on the side towards the combustion space 16) is constant and is between 0° and 90°, in particular between 30° and 75°, and is for example 45° or 60°.

[0048] There is a space 30 between the outlets 27, 29 and the impact plate 34. In the embodiment shown in [Fig.l], during operation, a free liquid layer 40, here internal, is formed inside the space 30 by the first fuel component 36 and a free liquid layer 42, here external, is formed by the second fuel component 38.

[0049] As shown in [Fig.2], the inner channel 26 may (e.g. at a certain operating point) also be led up to the impact plate 34 and the gap 30 to the inner channel 49 may be so small that the first component of fuel 36 radially internal 36 forms a fluid layer on the impact plate 34 immediately after its exit from the outlet 27 without forming a liquid layer. In this configuration, only a single partially free liquid layer 42 is formed during operation, which only bears against the wall of the channel 50 on its internal face.

[0050] In the embodiment shown [Fig.l], the size of the gap 30 is small enough that, during operation, the liquid layers 40, 42 with the fuel components 36, 38 used do not interact with each other due to instabilities (e.g. nebulization, perforation). Furthermore, the size of the gap 30 is chosen to be large enough relative to the two outlets 27, 29 so that during operation there is sufficient space between the outlets 27, 29 and the impact plate 34 for the formation of the fluid layer (see also [Fig.2]).

[0051] The channels 26, 28 and / or the outlets 27, 29 are also designed, in particular with regard to the channel height (slot height) and the length, so that during operation, with the respective good mass flow rate, the liquid layers 40, 42 form stable conical fluid layers.

[0052] The channels 26, 28 and / or the outlets 27, 29 are designed and / or arranged relative to each other in such a way that the liquid layers 40, 42 do not interact at least substantially with each other within the space 30. The liquid layers 40, 42 may, for example, flow parallel to each other or the radially outer liquid layer 42 may be oriented more obliquely (with a larger angle α) than the radially inner liquid layer 40 to reduce the impact impulse at the contact area. In this way, the fuel components 36, 38 strike the impact plate 34 at different contact areas 44, 46 and do not intersect, each forming a contact ring here.

[0053] For the design, preliminary (experimental) tests or computer-aided numerical simulations with the relevant fuels and / or in the relevant operating range can be carried out.

[0054] Such liquid layers 40, 42 can form in particular at relatively low flow speeds (e.g. less than 100 m / s), whereby the pressure loss across the injection device 10 can advantageously be kept relatively low.

[0055] Furthermore, the channels 26, 28 and / or the outlets 27, 29 are designed in such a way that an angle a between the channels (with respect to the central axes of the channels) and / or between the liquid layers 40, 42 formed during operation and the impact plate 34 (where the angle a is adjacent to the inclination angle |3) is between 90° and 180°, in particular between 90° and 145°, or between 90° and a maximum angle of "180° - [3". In particular, the channels 26, 28 are also oriented at an angle a with respect to the impact plate 34. The choice of these angles causes, during operation, a radially outward flow impulse after the liquid layers 40, 42 have struck the impact plate 34.

[0056] In a preferred embodiment, the injection device 10 comprises three functional parts for guiding the fluid, in particular rotationally symmetrical parts, a first part 20, a second part 22 and a third part 24. The parts can be manufactured by turning for example. In particular for manufacturing reasons, there can also be more parts and / or at least one of the three functional parts can be composed of several parts.

[0057] The first part 20, which comprises the impact plate 34, is arranged centrally and with symmetry of revolution, the longitudinal axis L forming the central axis or axis of rotation. At the axial level of the channels 26, 28, the first part 20 comprises a conical section 200 whose internal wall extends parallel to the internal channel 26.

[0058] In the embodiment shown [Fig.l], a cylindrical section 210 adjoins the conical section 200 (axially in the direction of the combustion space 16) which is arranged in the axial zone of the space 30.

[0059] Another conical section 220 on which the impact plate 34 is formed adjoins the cylindrical section 210 (axially towards the combustion space 16). The conical section 220 or the impact plate 34 extends from the inner edge 49 to the outer edge 50 of the impact plate 34.

[0060] In the embodiment shown in [Fig.2], the conical section 200 is directly adjoined by the conical section 220 or by the impact plate 34.

[0061] A cylindrical section 230 by which the first part 20 ends axially by its projecting side in the combustion space 16 adjoins the conical section 220.

[0062] The second part 22 and the third part 24 each comprise, for example, conical walls parallel to each other, the second part 22 being arranged all around the conical section 220 and the third part 24 being arranged all around the second part 22.

[0063] The inner channel 26, here the inner annular slot 260, is formed between the conical section 200 of the first part 20 and the second part 22. The outer channel 28, here the outer annular slot 280, is formed between the second part 22 and the third part 24.

[0064] Preferably, two of the three parts 20, 22, 24, for example the first part 20 and / or the second part 22, are arranged to be axially movable relative to each other or relative to a fixed part by means of an existing adjustment mechanism (not shown here).

[0065] The adjustment mechanism may be designed to be self-regulating, the slot heights of the annular slots 260, 280 being adjusted during operation at by means of the system pressure inside the injection device 10 as a driving force. For this purpose, the adjustment may for example include a suitably designed spring device (not shown here).

[0066] In this context, the respective distribution chambers of the fuel components 36, 38 (not shown here) can be coupled to the adjustment mechanism, the volume in each distribution chamber being reduced compared to the situation with the channels 26, 28 open when the injection device 10 is closed (reduction of the zero-crossing sections). Thus, when the injection device 10 is closed, a residual volume of fuel components 36, 38 remaining in the injection device 10 can be reduced to a minimum. This provides significant safety advantages, in particular when using a combination of hypergolic fuels. On the other hand, when the injection device is open, the volume in each respective distribution chamber can be increased, as a result of which the flow velocities are reduced and the pressure losses remain limited.

[0067] During operation, the two fuel components 36, 38 are introduced into each one of the channels 26, 28 from separate distribution chambers (not shown here) from an inlet side 12, which is not shown in detail here.

[0068] In a preferred embodiment, the fuel component which, when flowing from the impact plate 34 after striking it, has a higher flow momentum than the other fuel component, for example due to a higher mass flow rate, forms the inner fuel component 36, the inner fuel component 36 preferably having a higher flow velocity than the outer fuel component 38. In this way, indefinite splashing or upward spraying when the two fuel components meet (up-wash formation) can be avoided upon impact. A design with at least substantially identical flow momentum of the two fuel components, such as for example in conventional Pintle injectors, is not necessary in the present case.Instead, in the present injection device 10 according to the invention, different flow pulses can be advantageous for good mixing of the fuel. Suitable Weber numbers (ratio of inertial force to surface force) can be used for the design with each of the fuel components, whereby the advantageous Weber numbers can, for example, first be determined experimentally and / or by means of numerical design calculations.

[0069] The internal fuel component 36 flows without rotation through the internal annular gap 260 to the outlet 27. The internal fuel component 36 flows from the internal annular gap 260 without rotation forming the stable internal liquid layer 40 in the gap 30.

[0070] The fuel component 36 strikes the impact plate 34 near the inner edge 49 (particularly in the inner third of the impact plate 34) to form the inner contact area 44. Due to the circumferentially conical shape of the liquid layer 40, the inner contact area 44 is annular in shape all around. The fuel component 36 is deflected to flow radially outwardly along the impact plate 34. A fluid layer then forms on the impact plate 34, the thickness of which decreases as the distance from the longitudinal axis L increases.

[0071] The outer fuel component 38 flows without rotation through the outer annular gap 280 to the outlet 29. The outer fuel component 38 flows from the outer annular gap 280 without rotation forming the stable outer liquid layer 42 in the gap 30. The fuel component 38 impacts further outward than the fuel component 36 (farther from the longitudinal axis L) to form the outer contact area 46 on the impact plate 34 and (in the presence of the fuel component 36) on the fluid layer formed by the fuel component 36, which is called the "impact point". Due to the conical shape of the liquid layer 42, the outer contact area 46 is annular in shape. The fuel component 38 is deflected to flow radially outward along the impact plate 34.

[0072] The two fuel components 36, 38 thus form a common fluid layer, with the same flow direction, on the impact plate 34, the inner fuel component 36 first forming the lower layer and the outer fuel component 38 forming the upper layer. During the flow process on the impact plate 34, a mixing process occurs between the two fuel components 36, 38, which is dominated by turbulence in the liquid layer and by diffuse effects.

[0073] After the two fuel components 36, 38 have formed a common fluid layer on the impact plate 34, they flow out of it. The fluid mixture then forms a free fluid layer, which can also become unstable due to perforations and / or nebulization of the fuel components. The ejection angle of the fluid layer (corresponding to the inclination angle |3) is advantageously constant at any operating point due to the deflection in the axial-radial direction (without imparting rotation) by the impact plate 34.

[0074] The shut-off mechanism for adjusting the mass flow rates, in particular with respect to different operating points, is implemented by means of the adjustment mechanism with an axial movement, more precisely a translation, for example of the first part 20 and / or the second part 22 relative to the third part 24 and / or relative to each other. The conical shape of the flow geometry (channels 26, 28) changes the height of the annular gap 260 and / or the annular gap 280 and thus the flow sections of the channel 26 and / or the channel 28. A complete closure of the channel 26 and / or the channel 28, for example by analogy with a needle valve or a Swagelok® fitting, is thus possible.

[0075] The mass flow rates of the fuel components 36, 38 can be reduced independently of each other. In this way, the ratio of fuel to oxidant can be adjusted individually during operation without significantly changing the extent of spraying in the combustion space 16. If only one of the channels 26, 28 is completely closed, the other fuel component 38, 36 can be used as a monopropellant fuel (e.g. hydrogen peroxide), with only one fuel component reacting chemically (in particular being degraded) with energy release.

[0076] For example, to reduce at least one mass flow rate from a defined operating point, the first part 20 and / or the second part 22 are moved such that the at least one flow section decreases. By means of an additional pressure adjustment on the inlet side 12, in particular in a fuel supply system for supplying the fuel components 36, 38 into the channels 26, 28, the mass flow rate can be adjusted such that the liquid layers 40, 42 do not come into contact with each other. In this way, the reduction of the mass flow rate is advantageously possible in a relatively low pressure range within the fuel supply system.

[0077] In summary, the injection device 10 according to the invention allows stable and defined operation of the combustion chamber over a wide operating range.

Claims

1. Claims Injection device (10) for injecting a liquid-liquid fuel combination, in particular hypergolic, into a combustion space (16) of a combustion chamber of a spacecraft, the injection device (10) comprising - an impact plate (34) which fuel components (36, 38) strike during operation, and - at least one first channel (26) with a first outlet (27) arranged at its downstream end and at least one second channel (28) with a second outlet (29) arranged at its downstream end for conducting each of the fuel components (36, 38) and causing the fuel components (36, 38) to strike the impact plate (34), the channels (26, 28) being for example conical with respect to a longitudinal axis (L) of the injection device (10), the channels (26, 28) and the outlets (27, 29) being arranged with respect to each other in such a way that the fuel components (36, 38) strike the impact plate (34) at contact zones located at different locations from each other (44, 46), the contact zone or contact zones of one of the fuel components (36, 38) being in particular positioned radially further away from the other. the outside, further from the longitudinal axis (L) of the injection device (10), a space (30) being formed between at least one of the outlets (27,29) and the impact plate (34), within which, during operation, at least the fuel component (36, 38) flowing from one of the channels (26, 28), for example from the outer channel (28), forms a free or partially free liquid layer (40, 42), the impact plate (34) extending, for example conically, around the longitudinal axis (L) and is inclined radially outwards in the direction of flow, characterized in that, the channels (26, 28) are made in the form of conical coaxial annular slots (260, 280), forming at least one radially inner channel (26) and at least one radially outer channel (28), an angle (a) between the channels (26, 28) and / or between the liquid layers (40, 42) and the impact plate (34) being between 90° and a maximum angle of 180° - [3, where [3 corresponds to an inclination angle between the longitudinal axis (L) and / or a line parallel thereto and the impact plate (34), and an angle of inclination (|3) between the longitudinal axis (L) and the axial-radial surface being between 30° and 75° and equal for example to 45° or 60°.

2. Injection device (10) according to claim 1, characterized in that the channels (26, 28) and the outlets (27, 29) are designed and / or spaced from each other in such a way that the fuel components (36, 38), in particular the liquid layers (40, 42), do not interact at least substantially with each other before striking the impact plate (34).

3. Injection device (10) according to any one of the preceding claims, characterized in that the impact plate (34) and / or the channels (26, 28) are arranged coaxially with respect to each other and are rotationally symmetrical about the longitudinal axis (L).

4. Injection device (10) according to any one of the preceding claims, characterized in that the axial-radial size of the impact plate (34) and / or the position of the contact zones (44, 46) on the impact plate (34) is designed in such a way that, during operation, the ignition of the fuel components (36, 38) takes place after they have flowed from the impact plate (34), into the combustion space (16).

5. Injection device (10) according to any one of the preceding claims, characterized in that the impact plate (34) has a catalytically active material, in particular contains it and / or is formed from it and / or is coated with it and / or is designed to be heatable.

6. An injection device (10) according to any one of the preceding claims, characterized in that the injection device (10) comprises or is formed from three rotationally symmetrical parts, the impact plate (34) being arranged on a first part (20) disposed in the center of the longitudinal axis (L), the first part (20) being arranged in a section, which may be conical and located upstream of the impact plate (34), of a second part (22), which may be conical in shape, the second part (22) being coaxially surrounded by a third part (24), which may be conical, the inner annular gap (260) being formed between the first part (20) and the second part (22) and the annular gap outer part (280) being formed between the second part (22) and the third part (24).

7. Injection device (10) according to claim 6, characterized in that the three parts (20, 22, 24) are arranged movably relative to each other by means of an adjustment mechanism for adjusting a gap height of the annular gaps (260, 280), in particular with axial mobility of the first part (20) and / or the second part (22).

8. Injection device (10) according to claim 7, characterized in that the adjustment mechanism is designed to be self-regulating, the slot heights of the annular slots (260, 280) being adjusted by means of system pressure as driving force, the adjustment mechanism in particular comprising a suitably designed spring device.

9. Injection device (10) according to any one of the preceding claims, characterized in that at least one of the annular slots (260, 280) is designed to be completely closable, the volume of a distribution space which is in fluid connection with the at least one annular slot (260, 280) being in particular designed to be reduced when it is closed.

10. A method for injecting a liquid-liquid fuel combination, in particular hypergolic, into a combustion space (16) of a combustion chamber of a spacecraft, by means of an injection device (10) according to any one of the preceding claims, wherein - a first fuel component (36) flows in at least one first channel (26) and via a first outlet (27) arranged at the downstream end of the first channel (26), a second fuel component (38) flows in at least one second channel (28) and via a second outlet (29) arranged at the downstream end of the second channel (28), - downstream of the outlets (27, 29), the fuel components (36, 38) strike an impact plate (34), and the fuel components (36, 38) are caused to strike the impact plate (34) at contact zones (44, 46) which are located in different places from each other,the contact area or areas of one of the fuel components (36, 38) being in particular positioned radially further outward, further from the longitudinal axis (L) of the injection device (10), characterized in that the flow pulses of the fuel components are different, the flow pulse of the radially inner fuel component (36) being greater than the flow pulse of the radially outer fuel component (38).

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