Injector device, combustion chamber system and method for introducing reactive fluid into a combustion chamber

Abstract

Injector device (2) for use in a combustion chamber system (1) of a rocket engine, through which a reactive fluid (42) that becomes flammable upon the introduction of ignition energy can be introduced into a combustion chamber (10) of the combustion chamber system (1), wherein the injector device (2) is aligned with respect to a central axis (M), with - a flow path which can be brought into flow connection upstream with a supply device (40) for the reactive fluid (42) and downstream with the combustion chamber (10), and - a flame arresting device (35) arranged in the flow path to prevent flame flashback into the supply device (40), wherein the injector device (2) has a feed device (20) which is arranged downstream of the flame arrestor device (35), so that the feed device (20) can be positioned in the combustion chamber system (1) between the flame arrestor device (35) and the combustion chamber (10), and which comprises at least one feed opening (25) through which the flow path opens into the combustion chamber (10) and the reactive fluid (42) can be introduced into the combustion chamber (10) during operation, wherein the feed device (20) comprises an end plate (24) which is arranged between the flame arrestor device (35) and the combustion chamber (10) and wherein the total flow cross-section of the flow path in the at least one feed opening (25) is reduced compared to the flow cross-section within the flame arrestor device (35), wherein the flame arrestor device (35) and the feed device (20) are designed such that a significantly higher pressure drops across the feed device (20), with a pressure difference of more than a factor of 1.5, than across the flame arrestor device (35).

Description

[0001] The invention relates to an injector device for use in a combustion chamber system of a rocket engine, through which a reactive fluid can be introduced into a combustion chamber of the combustion chamber system, wherein the injector device is aligned with respect to a central axis, with a flow path that can be brought into flow contact upstream with a supply device for the reactive fluid and downstream with the combustion chamber, and a flame arrestor device arranged in the flow path to prevent a flame flashback into the supply device.

[0002] Novel propellants for rocket engines pose challenges to the systems within the engines designed for propellant storage and / or energy conversion. Promising new propellants include mixtures of nitrous oxide (N₂O) as an oxidizer and hydrocarbons, such as ethene (C₂H₄), as fuel. These propellant mixtures are preferably stored premixed and introduced into a combustion chamber system of the rocket engine. The separate introduction of oxidizer and fuel into the combustion chamber is thus eliminated.

[0003] Since the propellant mixture is premixed and therefore ignitable in large parts of the periphery, a key task is to prevent flame flashback from the combustion chamber system into this periphery of the rocket engine. The periphery includes, for example, a tank structure with a storage unit and a supply system to the combustion chamber system. Flame flashback into the periphery could lead to the destruction of the rocket engine and potentially to the loss of the entire spacecraft. The risk of flame flashback is particularly high during transient conditions, such as engine ignition.

[0004] An injector device of the type described above, designed to prevent flame flashback during operation with premixed fuels, is known from US 8,572,946 B2. In the injector device described therein, a porous medium is arranged in the flow path of the injector device to prevent flame flashback, and this medium is adjacent to the combustion chamber. The fuel mixture flows through the porous medium into the combustion chamber, where it is fed to the combustion chamber.

[0005] A disadvantage of this device is that the flame remains very close to the injector assembly during operation. This results in high thermal stress, which, especially during extended operation, can lead to overheating and damage to the injector assembly. Furthermore, if the heat is conducted upstream of the flame arrestor within the injector assembly, there is a risk of ignition of the fuel mixture.

[0006] DE 10 2007 063 539 A1 discloses a combustion chamber device with two injector assemblies for the separate introduction of two fluids (fuel and oxidizer) into a combustion chamber. Each injector assembly comprises a porous element. The second injector assembly also includes a fluid guide element and a plurality of fluid lines.

[0007] DE 196 25 735 C1 shows an injection head for use also in monoergolic operation. The injection head has a front wall with through-channels.

[0008] US patent 2012 / 0279196A1 shows injector systems for use with monopropeller fuels or premixed fuels, each featuring a flame arrestor to prevent flame flashback. Support structures may be provided for mechanical stabilization of the flame arrestor.

[0009] The invention is based on the objective of providing an injector device that ensures safe and reliable operation with premixed propellants. Furthermore, the invention is based on the objective of providing a combustion chamber system with a corresponding injector device and a method for introducing reactive fluid into a combustion chamber of a rocket engine.

[0010] The problem is solved for the injector device with the features of claim 1. It is provided that the injector device has a supply device which is arranged downstream of the flame arrestor device, such that the supply device can be positioned (or is positioned in the installed state) in the combustion chamber system between the flame arrestor device and the combustion chamber (or its combustion chamber), and which comprises at least one supply opening through which the flow path opens into the combustion chamber, in particular its combustion chamber, and the reactive fluid can be introduced into the combustion chamber (or its combustion chamber) during operation.

[0011] The reactive fluid is a liquid and / or gaseous propellant for the rocket engine (a phase change can occur between a storage device and the combustion chamber). The reactive fluid is flammable upon the application of ignition energy and is a premixed propellant mixture of fuel and oxidizer before being fed into the combustion chamber. A single-component propellant (a so-called monopropellant) is also possible. In particular, the propellant can be a mixture of nitrous oxide (N₂O) as the oxidizer and hydrocarbons, e.g., ethene (C₂H₄), as the fuel. The terms "reactive fluid" and "propellant" are used synonymously here.

[0012] The at least one inlet opening forms, in particular, a downstream section of the flow path. If multiple inlets are present, this section of the flow path comprises several flow segments formed by the multiple inlets. The total flow cross-section is then the sum of the flow cross-sections of the inlets. The flow cross-section within the flame arrestor corresponds to the free flow cross-section within the flame arrestor body, i.e., a sum of capillary cross-sections (in the case of a capillary structure of the flame arrestor body) or taking into account the porosity (in the case of a porous structure). The injector device is, for example, designed along the central axis and / or symmetrically circumferentially around it. The inlet device can be designed, for example, in the form of a showerhead configuration, an impact jet configuration, or a swirl configuration.This design allows the flame to be kept at a distance from the injector device with the flame arrestor. The flame arrestor is protected from overheating and damage. In this way, safe and reliable operation of the injector device and / or the combustion chamber system is ensured.

[0013] Particularly advantageous for achieving a lower thermal load on the injector is, according to the invention, that the total flow cross-section of the flow path in the at least one supply opening, especially at the downstream end of the supply opening which leads into the combustion chamber, is reduced compared to the flow cross-section within the flame arrestor device. The flame arrestor device and the supply device are designed such that a significantly higher pressure drop occurs at the supply device, with a pressure difference of more than a factor of 1.5, than at the flame arrestor device. Preferably, the total flow cross-section is less than half, preferably less than 1 / 4, e.g., 1 / 6, of the flow cross-section of the flame arrestor device. Preferably, the speed of sound is reached at the outlet of the supply device.

[0014] The reduction of the flow cross-section is such that, taking into account a pressure difference across the supply device, the flow velocity of the reactive fluid within the supply opening(s) (at least at their downstream end(s)) is higher than at the downstream end of the flame arrestor, e.g., by more than a factor of 2, in particular by more than a factor of 4 or 6. The increase in flow velocity results directly from the reduced flow cross-section. Furthermore, the flame arrestor and the supply device are designed such that (particularly due to the cross-sectional reduction) the pressure drop across the supply device is significantly higher (with a pressure difference of more than a factor of 1.5, preferably a factor of 2) than across the flame arrestor.This pressure drop causes a reduction in density, and the associated increase in volume flow also accelerates the flow. As a result, the reactive fluid enters the combustion chamber at a higher velocity than it exhibits when flowing through the flame arrestor, particularly at the downstream end. Specifically, the total flow cross-section at the downstream end of the feed opening(s), i.e., the opening into the combustion chamber, is designed, taking into account the operating conditions (including pressure and temperature range and fuel mass flow), such that the fuel is introduced into the combustion chamber at a high exit velocity, e.g., an axial velocity between 50 and 160 m / s. The exit velocity is determined primarily by the composition of the reactive fluid and its (turbulent) flame velocity under the relevant operating conditions.The exit velocity is designed such that the flame root (the upstream end of the flame) is maintained at a certain distance from the injector device during steady-state operation, for example, a multiple of the diameter of the feed opening, e.g., at least five times. This distance is such that the thermal stress on the injector device remains low even over extended operating periods and, for example, maximum temperatures remain below the maximum operating temperature of the material used, e.g., below 550 °C. This protects the injector device from overheating and damage. Additionally, this prevents flame flashback caused by reignition upstream of the flame arrestor due to a hot surface in contact with the reactive fluid. This ensures safe and reliable operation of the injector device and / or the combustion chamber system.

[0015] According to the invention, the feed device comprises an end plate, which is preferably aligned perpendicular to the central axis. The end plate is arranged between the flame arrestor and the combustion chamber. In this way, the flame arrestor is also additionally protected from radiant heat from the combustion chamber.

[0016] Preferably, the at least one supply opening is formed in the end plate, with the supply opening running through the end plate in a channel-like manner and being aligned, in particular, parallel to the central axis (i.e., axially). The at least one supply opening is formed, for example, by a bore through the end plate. It can also include further sections upstream or downstream of the end plate, e.g., nozzle attachments. However, a design such that the thickness of the end plate corresponds to the axial extent of the supply opening is particularly optimized for component size and resistant to thermal stress. Due to the channel-like design and, in particular, the parallel alignment of the supply opening, the flow can be introduced into the combustion chamber with a high axial momentum, thereby effectively keeping the flame root (at least in steady-state operation) spaced away from the injector device, especially axially.

[0017] If multiple feed openings are present (e.g., between 10 and 20, e.g., 16), the axial flame length can be advantageously shortened. One reason for this is the increase in the contact surface of the reactive fluid, which is brought into contact with the combustion chamber environment upon introduction. This can, for example, accelerate the mixing of the fresh, reactive fluid with hot combustion gases and thus the onset of the combustion reaction. Shortening the flame length allows for a more compact axial design of the combustion chamber, which in turn offers weight advantages. The feed openings can be, for example, uniformly distributed in the end plate, at least in certain areas, or configured as at least one nozzle ring, e.g., equidistant and / or circumferential around the central axis.The number and / or design of the feed ports can also be parameters used to influence the distance between the flame root and the injector device. For example, a jet force (mass flow rate (reactive fluid) per port multiplied by the exit velocity) of 0.0625 N has proven advantageous for flame stabilization when the flame is positioned at a sufficient distance from the injector device. This can be achieved, for example, with a showerhead configuration featuring 16 feed ports.

[0018] Preferably, the inlet opening has an upstream inlet region and a downstream outlet region, with the cross-section of the outlet region being smaller than that of the inlet region. This prevents the flow from being forced through such a narrow cross-section over the entire distance as is necessary to achieve the high outlet velocities. In this way, the pressure loss across the inlet opening can be reduced compared to a design with, for example, a constant cross-section.

[0019] Reliable prevention of flame flashback is achieved by arranging the flame arrestor device in an injector chamber upstream of at least one supply opening and occupying (essentially) the entire cross-section (perpendicular to the central axis) of the injector chamber in an axial region. Preferably, the flow of the reactive fluid in the injector chamber is a single, unbroken flow, not yet divided into partial flows (as would be the case, for example, with multiple supply openings). The injector chamber thus serves as a kind of plenum or distribution area for the reactive fluid before it enters the at least one supply opening. The flow path is then formed, for example, by the injector chamber as the upstream section and one or more supply nozzles as one or more downstream sections.In this design variant, advantageously only one flame arrestor device is required within the injector device to prevent flame flashback. Due to its arrangement across the entire cross-section, the flame cannot propagate further upstream past the flame arrestor. "Essentially" means that additional means can be arranged alongside the flame arrestor device to prevent flame flashback in conjunction with it, e.g., sealing materials. The axial area in which the flame arrestor device is arranged is large enough to reliably extinguish the flame (flame quenching) within the flame arrestor device. The axial length can be designed, in particular, by considering the type of reactive fluid and the operating conditions (e.g., mass flow rate, pressure and temperature range), e.g.,based on reaction kinetic calculations, literature data and / or preliminary experimental tests.

[0020] If the flame arrestor (in the injector chamber) is located directly upstream of at least one feed port, unwanted flame stabilization within the injector chamber, e.g., between the flame arrestor and the feed device, is prevented. There is no space between the flame arrestor and the feed device in which a flame could permanently stabilize. A flame stabilized there could destroy the flame arrestor and subsequently propagate upstream. This design thus further increases operational safety.

[0021] Preferably, the injector device is modular in design, with a first part comprising an injector body with the feed device and a second part comprising a support device that holds the flame arrestor. The support device, in particular with a circumferential wall, encloses the injector chamber in which the flame arrestor is arranged. The feed device for the upstream opening into the injector chamber can, for example, be attached to the second part, particularly to the support device. The first part can, for example, be designed for attachment to the combustion chamber, particularly to the injector head. This modular design makes it possible to easily provide an injector device tailored to a specific thrust class, mass flow rate, type of reactive fluid, and corresponding operating conditions (pressure and temperature ratios).For use with different pressure classes and / or fuels, one of the parts of the injector assembly can be replaced. This also offers assembly advantages, as the flame arrestor can first be inserted into the carrier assembly and then more precisely positioned in the injector body. In a non-modular design, it would be conceivable that a wall surface surrounding the injector chamber could be assigned to, or form part of, an injector head or injector body.

[0022] Preferably, the support device has a circumferential wall surrounding the flame arrestor device, by means of which the flame arrestor device is held (by force-fit, form-fit, and / or material-fit), wherein the circumferential wall is inserted into a chamber of the injector body with at least one downstream section. The circumferential wall is, for example, aerodynamically cylindrical about its central axis. The flame arrestor device bears at least indirectly, and in particular circumferentially, against an inner wall surface of the circumferential wall. The support device is attached to the injector body so that secure positioning is achieved during operation, for example, with fasteners and / or by force-fit, form-fit, and / or material-fit. An outer wall surface of the circumferential wall bears, in particular circumferentially, against an inner wall surface of the chamber, at least indirectly. "At least indirectly" means, for example, with the interposition of a sealing material.Thus, the support device and the circumferential wall are designed in a sleeve-like form and inserted into the injector body and the space within the injector body. The flame arrestor and the circumferential wall, as well as the circumferential wall and the inner wall surface surrounding the space, have correspondingly complementary cross-sectional shapes, which are, for example, circular. The contact between the circumferential wall and the inner wall surface can be partial or extend over the entire axial extent of the inner wall surface, but at least such that the support device is securely held to the injector body. Preferably, the circumferential wall extends to the end plate, which is arranged at the downstream end of the injector space.

[0023] A secure hold of the flame arrestor in the carrier device and simple mounting options in the injector body or on a supply line device result if the axial extent of the circumferential wall corresponds at least to the axial extent of the flame arrestor.

[0024] Upstream flame propagation can be reliably prevented if a sealing element to prevent flame propagation is arranged between the injector body and the flame arrestor, in particular between the circumferential wall and the flame arrestor and / or between the circumferential wall and the inner wall surface. In this way, for example, the flow of reactive fluid through microchannels in this area, through which a flame could also flash back, can be prevented. For this purpose, the sealing element is preferably arranged in a closed, radially circumferential manner. In the case of a non-modular design, the sealing element is preferably located between the flame arrestor and the inner wall, surrounding the injector chamber.

[0025] Weight advantages result from the fact that the sealant is made of a temperature-resistant plastic material (e.g. resistant up to a temperature of 130 °C or higher), e.g. Teflon.

[0026] For precise, simple positioning of the flame arrestor device during assembly, a stop device for axial positioning of the support device on the injector body is preferably formed on the outer wall surface of the circumferential wall, in particular at least partially circumferentially.

[0027] Preferably, the stop device is in contact with the injector body via a sealing surface, particularly one oriented perpendicular to the central axis, e.g., with a complementary sealing surface of the injector body. A sealing element, for example, a flat gasket, an O-ring, or the like, is preferably arranged between these surfaces to achieve a gas-tight seal. Preferably, the stop device also has a further sealing surface opposite (parallel to) the first sealing surface, e.g., for a gas-tight seal between the injector device and a periphery surrounding the combustion chamber system or the injector head.

[0028] A flame arrestor device can be designed to be lightweight and compact if it incorporates a flame arrestor body with a porous and / or capillary structure, particularly one made of sintered material or a granular material. The pore and / or capillary diameter is designed to ensure reliable flame extinguishing within the relevant operating range, especially the pressure range, preferably resulting in a lower pressure drop than at the supply device. The design is based, in particular, on knowledge of the type of reactive fluid and the operating conditions (e.g., mass flow rate, pressure and temperature range), for example, on reaction kinetic calculations, literature data, and / or preliminary experimental tests. For instance, a sintered material with a porosity of 30% has proven suitable as a porous structure.

[0029] The problem is solved for the combustion chamber system by the features of claim 15 and for the method by the features of claim 16. The corresponding embodiments and configurations described for the injector device apply mutatis mutandis to these claims.

[0030] The invention will now be explained in more detail using an exemplary embodiment and with reference to the drawings. The drawings show: Fig. 1 a combustion chamber system with an injector device according to the invention in a perspective sectional view and Fig. 2 the injector device according to the invention in a lateral sectional view.

[0031] Fig. Figure 1 shows a combustion chamber system 1 for use in a rocket engine with an injector device 2 according to the invention for introducing a reactive fluid 42 into a combustion chamber 10 in a perspective sectional view. The combustion chamber system 1 comprises a supply device 40 for supplying the reactive fluid 42 to the injector device 2. The combustion chamber system 1 can be connected via the supply device 40 to further supply peripherals for the reactive fluid (comprising, for example, a tank structure with a storage device, not shown here).

[0032] The combustion chamber system 1 comprises the combustion chamber 10 with an inlet-side injector head 16, to which the injector device 2 may be assigned or into which the injector device 2 is installed and / or which forms at least a part of the injector device 2. The supply line 40 opens into the injector device 2 at or within the injector head 16. The combustion chamber 10, with a wall 11, encloses a combustion chamber 12. The wall 11 is, by way of example, essentially cylindrical around a central axis M, so that the combustion chamber 12 has a circular cross-section.

[0033] The combustion chamber 12 extends along the central axis M, with which it is essentially symmetrical (e.g., apart from internal components such as an ignition device 14, 15). At an outlet end of the combustion chamber 10, the combustion chamber 12 opens into a combustion chamber outlet 13 located there. Projecting into the combustion chamber 12 are, for example, a first ignition device 14, such as a spark plug, and a second ignition device 15, such as a glow plug, for igniting the reactive fluid 42 during a rocket engine start. It is also possible for only one ignition device 14, 15 to be present, or for the ignition device 14, 15 to be arranged and / or configured differently. Furthermore, as shown here by way of example, measuring bores 50 may be present to monitor the operation of the combustion chamber system 1.

[0034] The reactive fluid 42 is a liquid and / or gaseous propellant for the rocket engine (a phase change can occur between the storage unit and the combustion chamber 10). Specifically, the reactive fluid 42 is flammable upon the application of ignition energy; that is, it is a propellant mixture of fuel and oxidizer that is already premixed upon introduction. A single-component propellant (a so-called monopropellant) is also possible. In particular, the propellant can be a mixture of nitrous oxide (N₂O) as the oxidizer and hydrocarbons, e.g., ethene (C₂H₄), as the fuel.

[0035] The supply line 40 leads into the injector device 2. The injector device 2 is in Fig.Figure 2 shows a lateral sectional view. The injector device 2 comprises an injector chamber 22, which extends along the central axis M and is, by way of example, symmetrically designed with respect to it. The injector chamber 22 forms a first, upstream section of a flow path for the reactive fluid 42 in the injector device 2. The injector chamber 22 has an opening on the upstream side through which the reactive fluid 42 is introduced into the injector chamber 22 during operation by means of the supply device 40. The coupling with the supply device 40 is not shown here. In this example, the upstream opening is arranged perpendicular to the central axis M and is symmetrically designed with respect to it, in particular circular. The shape and / or arrangement of the opening may differ depending on the arrangement and / or design of the combustion chamber system 1 and its surrounding periphery.The injector chamber 22 is, by way of example, designed to be aerodynamically efficient and cylindrical, and is circumferentially bounded by an inner wall surface 38. In this case, the inner wall surface 38 is specifically associated with a support device 28 of the injector device 2. It would also be possible for the inner wall surface 38 to be associated with an injector body 21 and / or the injector head 16, or to form a part of them.

[0036] The injector device 2 further comprises a flame arrestor 35, which is arranged in the flow path, specifically in the injector chamber 22. During operation, e.g., during transient conditions such as ignition processes, etc., the flame arrestor 35 prevents flame flashback from the combustion chamber 10 into the supply line 40 and from there into the further supply periphery. The flame arrestor 35 is arranged such that it occupies the entire cross-section of the injector chamber 22 (perpendicular to the central axis M) within an axial range. This prevents a flame from propagating upstream through the injector chamber 22 into the supply line 40, away from the flame arrestor 35.For this purpose, a sealing element 32 is arranged between the flame arrestor 35 and the inner wall surface 38, extending in particular radially around and over the entire contact area between the flame arrestor 35 and the inner wall surface 38. To save weight, the sealing element 32 is made of a plastic material, in particular a temperature-resistant one, e.g., Teflon.

[0037] The flame arrestor 35 comprises a flame arrestor body 33, which is formed from a porous and / or capillary structure, in particular from porous sintered material or a sphere-filled material, and / or with capillary channels oriented in the same direction. This advantageously allows for a compact, lightweight flame arrestor 35. Within the flame arrestor body 33, in the event of a flame flashback, the flame is extinguished by heat dissipation to the flame arrestor body 33 ("flame quenching"). The flame arrestor body 33 is designed with respect to the pore or capillary diameter ("quenching diameter") and / or the axial extent for a corresponding operating range, in particular a relevant expected pressure and temperature range and mass flow rate, for a specific reactive fluid 42, such that reliable flame extinguishing takes place. Relevant pressures can, for example, be between 5 and 25 bar, whereby, for example,Peak values ​​during transient conditions can be even higher. Combustion temperatures, for example, are on the order of 3000 °C. Design is carried out, for example, using reaction kinetic calculations, literature data, and / or preliminary experimental tests.

[0038] Furthermore, the injector device 2 comprises a supply device 20 with, by way of example, several supply openings 25 leading into the combustion chamber 10, more precisely into the combustion chamber 12. The supply device 20 is arranged downstream of the injector chamber 22, between the flame arrestor device 35 and the combustion chamber 10 or the combustion chamber 12. The supply openings 25 form downstream sections of the flow path of the injector device 2; that is, downstream of the injector chamber 22, the flow path splits between the supply openings 25 and leads into the combustion chamber 10 or the combustion chamber 12.

[0039] The supply device 20 is shown here as an example in the form of a showerhead configuration. The supply openings 25 are formed in an end plate 24 of the supply device 20, which is oriented perpendicular to the central axis M. The supply openings 25 run through the end plate 24 in a channel-like manner and, in particular, parallel to the central axis M. Other configurations of the supply device 20 would also be possible, for example, in the form of an impact jet configuration or a swirl configuration.

[0040] The end plate 24 has several feed openings 25 (e.g., 19), which, by way of example, are distributed essentially over the entire surface of the end plate 24. A circumferential circular arrangement, similar to a nozzle ring around the central axis M, would also be conceivable. The presence of multiple feed openings 25 allows the flame length, and thus the length of the combustion chamber 10, to be reduced compared to a design with only one feed opening 25, resulting in a weight advantage.

[0041] The inlet openings 25 have an upstream inlet region 26, which transitions via a cross-sectional constriction into a downstream outlet region 27. The outlet region 27 opens into the combustion chamber 10. In this way, the length of the section in which the flow of the reactive fluid 42 is accelerated to the outlet velocity can be reduced, thus reducing the pressure loss.

[0042] The flame arrestor 33 is arranged directly upstream of and adjacent to the end plate 24 and the supply openings 25. In this way, the flame arrestor 33 occupies the injector chamber 22 directly upstream of the supply openings 25. This prevents any free space within the injector chamber 22, where an upstream flame could stabilize. Thus, overheating of the injector assembly 2 upstream of the supply openings 25, including the flame arrestor 33, is prevented.

[0043] During operation, the reactive fluid 42 flows through the flow path of the injector device 2. The reactive fluid 42 is introduced as a single flow via the supply line 40 into the injector chamber 22, which forms the upstream section of the flow path. Within the injector chamber 22, the reactive fluid 42 flows through the flame arrestor 33. Immediately downstream of the flame arrestor 33, the reactive fluid 42, now divided into partial flows, flows through the supply openings 25 into the combustion chamber 10. The supply openings 25 are designed such that the total flow cross-section within the supply openings 25 (corresponding to a total flow cross-section) is reduced compared to the flow cross-section within the flame arrestor 35, i.e., the free flow cross-section within the flame arrestor 33.In this way, the flow of the reactive fluid 42 within the supply openings 25, particularly at their outlet opening into the combustion chamber 10, is accelerated to an exit velocity relative to the flow through the flame arrestor 35. Due to the channel-like design of the supply openings 25, which are aligned parallel to the central axis M, the reactive fluid 42 flows into the combustion chamber 10 with high axial momentum. Depending on the exit velocity, during operation, at a steady-state operating point, a flame root, i.e., the upstream end of the flame reaction zone, is positioned at a certain distance from the end plate 24.Knowing the operating conditions and the nature of the reactive fluid 42, the total flow cross-section at the downstream end of the supply openings 25, and thus the outlet velocity, can be designed such that a desired minimum axial distance between the flame root and the end plate 24 is maintained during steady-state operation. Flame anchoring directly to the injector device 2 or the end plate 24 is prevented, and the flame root is kept at a certain distance from the end plate 24 or the injector device 2 during steady-state operation. This reduces the thermal stress on the end plate 24 or the injector device 2 and protects the injector device 2 from overheating. Additionally, the heating of surfaces within or upstream of the injector device 2 is reduced. This prevents ignition of the reactive fluid 42 within or upstream of the injector device 2.

[0044] The injector device 2 is advantageously designed in a modular fashion. A first part comprises the injector body 21 with the feed device 20. The injector body 21 can be designed for attachment to the injector head 16. Alternatively, the injector body 21 could be part of the injector head 16. For contact with the combustion chamber 10 or the injector head 16, the first part has a sealing surface 36, which surrounds the feed openings 25 on the side of the end plate 24 facing the combustion chamber 10. A chamber 44 is formed in the injector body 21, which is, by way of example, cylindrical. The chamber 44 is circumferentially bounded by an inner wall surface 23 of the injector body 21. The feed device 20, in particular the end plate 24, is arranged on the downstream end face of the chamber 44.The space 44 is open on the upstream end face, and a second part of the injector device 2 is inserted from this side and connected to the injector body 21 e.g. with fastening means and / or by positive, force or material connection.

[0045] The second part of the injector device 2 comprises the carrier device 28, which has a sleeve-like circumferential wall 31. The circumferential wall 31 is, for example, cylindrically shaped and open at each end face. An inner wall surface 38 of the circumferential wall 31 forms the boundary of the injector chamber 22. The flame arrestor device 35, or flame arrestor element 33, is enclosed by the circumferential wall 31 for positioning within the injector chamber 22 and is held in the carrier device 28. The flame arrestor element 33 is attached, for example, by being pressed, soldered, glued, or otherwise positively, forcefully, and / or materially connected to the sleeve-like circumferential wall 31.

[0046] The circumferential wall 31 projects into the injector chamber 22 with its downstream section and indirectly abuts the inner wall surface 23 with an outer wall surface 37. "Indirectly" means with the interposition of a sealing material 32. For example, the support device 28 is also pressed into the injector body 21 in this way. The circumferential wall 31 extends to the end plate 24 in order to completely fill the space 44 upstream of the end plate 24 together with the flame arrestor device 35.

[0047] For secure and defined installation in the injector body 21, an annular stop device 29 is formed on the outer wall surface 37 of the circumferential wall 31, extending at least partially around the perimeter. The stop device 29 acts as a stop against the injector body 21, circumferentially around the upstream end face of the chamber 44. A first sealing surface 34, oriented perpendicular to the central axis M, is formed on the stop device 29, via which the flame arrestor device 35 is gas-tightly sealed against the injector body 21. An O-ring, a flat gasket, or another suitable seal serves as the sealing medium. The stop device 29 ensures a defined positioning of the flame arrestor device 35 during installation, preventing it from being inserted too far and damaging fine porous or capillary openings.

[0048] On the opposite (upstream) side, the stop device 29 has a second sealing surface 30, via which the injector device 2 is sealed against other parts of the injector head 16, for example, using the same sealing materials as the sealing surface 34 is sealed against the injector device 2.

[0049] For a secure hold of the flame arrestor 33 on the support device 28, the axial extent of the circumferential wall 31 corresponds at least to the axial extent of the flame arrestor device 35 or the flame arrestor 33. The axial extent of the flame arrestor 33 results from its flame quenching function via the aforementioned design tools (e.g., reaction kinetic calculations, literature data, experimental tests). Upstream, the circumferential wall 31 can be axially extended further than the flame arrestor device 35, e.g., to define the axial extent of the injector chamber 22, which may vary depending on the design of the combustion chamber system 1 and / or its periphery.

[0050] A sealing element 32 is arranged between the inner wall surface 38 of the circumferential wall 31 and the outer circumference of the flame arrestor 33 to prevent flame propagation between the support device 28 and the flame arrestor 33. For the sake of low weight, the sealing element 32 is made of a temperature-resistant plastic material, e.g., Teflon. This sealing element 32 is preferably also present between the outer wall surface 37 of the circumferential wall 31 and the inner wall surface 23 to prevent flame propagation upstream through this area.

[0051] The modular design of the injector device 2, comprising the injector body 21, including the supply device 20, and the carrier device 28, which holds the flame arrestor device 35, in particular the flame arrestor element 33, allows for good adaptation of the injector device 2 to engines of different thrust classes operating under different conditions, especially mass flow rates. This enables the simple production of an optimized injector device 2. A flame arrestor device 35 (with a corresponding extinguishing cross-section), optimized for a specific thrust class, a particular reactive fluid 42 and its mass flow rate, as well as for a corresponding pressure ratio (pressure in the supply periphery to combustion chamber pressure), can be combined with an injector body 21 comprising a correspondingly optimized supply device 20 (with a corresponding supply opening).Furthermore, the modular design allows for precise, simple manufacturing of the injector device 2. First, the carrier device 28 can be pre-assembled with the flame arrestor device 35 and then precisely inserted and fastened into the injector body 21.

[0052] The described embodiment shows an injector device 2 or a combustion chamber system 1 by means of which premixed fuels can be used safely. Furthermore, a long service life of the injector device is achieved by keeping its thermal stress low.

Claims

[1] Injector device (2) for use in a combustion chamber system (1) of a rocket engine, via which a reactive fluid (42) which is flammable upon introduction of ignition energy can be introduced into a combustion chamber (10) of the combustion chamber system (1), wherein the injector device (2) is aligned with respect to a central axis (M), with - a flow path which can be brought into flow connection upstream with a supply device (40) for the reactive fluid (42) and downstream with the combustion chamber (10), and - a flame arrester device (35) arranged in the flow path to prevent a flashback into the supply device (40), wherein the injector device (2) has a supply device (20) which is arranged downstream of the flame arrester device (35), so that the supply device (20) can be positioned in the combustion chamber system (1) between the flame arrester device (35) and the combustion chamber (10), and which comprises at least one supply opening (25) via which the flow path opens into the combustion chamber (10) and the reactive fluid (42) can be introduced into the combustion chamber (10) during operation, wherein the supply device (20) comprises an end plate (24) which is arranged between the flame arrester device (35) and the combustion chamber (10), and wherein the total flow cross-section of the flow path in the at least one supply opening (25) is reduced compared to the flow cross-section within the flame arrester device (35), wherein the flame arrester device (35) and the supply device (20) are designed such that a significantly higher pressure drops at the supply device (20), with a pressure difference of more than a factor of 1.5, than at the flame arrester device (35). [2] Injector device (2) according to claim 1, characterized by that the at least one supply opening (25) is formed in the end plate (24), wherein the supply opening (25) runs in a channel-like manner through the end plate (24). [3] Injector device (2) according to claim 2, characterized by that there are several feed openings (25). [4] Injector device (2) according to claim 2 or 3, characterized by that the feed opening (25) has an upstream inlet region (26) and a downstream outlet region (27), wherein the cross section of the outlet region (27) is reduced compared to the cross section of the inlet region (26). [5] Injector device (2) according to one of the preceding claims, characterized by that the flame arrester device (35) is arranged in an injector chamber (22) upstream of the at least one supply opening (25) and occupies the entire cross section of the injector chamber (22) in an axial region. [6] Injector device (2) according to claim 5, characterized by that the flame arrester device (35) is arranged directly upstream of the at least one supply opening (25). [7] Injector device (2) according to one of the preceding claims, characterized bythat the injector device (2) is of modular design, wherein a first part comprises an injector body (21) with the supply device (20) and a second part comprises a carrier device (28) which holds the flame arrester device (35). [8] Injector device (2) according to claim 7, characterized by in that the carrier device (28) has a circumferential wall (31) which runs around the flame arrester device (35) and by means of which the flame arrester device (35) is held, wherein the circumferential wall (31) is inserted with at least one downstream section into a space (44) of the injector body (21), wherein an outer wall surface (37) of the circumferential wall (31) bears at least indirectly against an inner wall surface (23) of the space (44). [9] Injector device (2) according to claim 8, characterized by that the axial extent of the peripheral wall (31) corresponds at least to the axial extent of the flame arrester device (35). [10] Injector device (2) according to claim 8 or 9, characterized by that a sealing means (32) for preventing flame propagation is arranged between the injector body (21) and the flame arrester device (35), in particular between the peripheral wall (31) of the carrier device (28) and the flame arrester device (35) and / or between the peripheral wall (31) of the carrier device (28) and the inner wall surface (23). [11] Injector device (2) according to claim 10, characterized by that the sealing means (32) consists of a temperature-resistant plastic material. [12] Injector device (2) according to one of claims 8 to 11, characterized by that a stop device (29) for axially positioning the carrier device (28) on the injector body (21) is formed on the outer wall surface of the peripheral wall (31). [13] Injector device (2) according to claim 12, characterized bythat the stop device (29) is in contact with the injector body (21) via a sealing surface (34). [14] Injector device (2) according to one of the preceding claims, characterized by that the flame arrester device (35) has a flame arrester body (33) with a porous and / or capillary structure. [15] Combustion chamber system (1) for use in a rocket engine, comprising a combustion chamber (10) and an injector device (2) according to one of the preceding claims for introducing a reactive fluid (42) into the combustion chamber (10). [16] Method for introducing reactive fluid (42) which is flammable upon introduction of ignition energy into a combustion chamber (10) of a rocket engine, with an injector device (2) according to one of claims 1 to 14, in which the reactive fluid (42) is guided via a feed device (40) into a flow path of an injector device (2), flows through a flame arrester device (35) within the flow path and is introduced into a combustion chamber (10) downstream of the flame arrester device (35), characterized by that the reactive fluid (42) is introduced downstream of the flame arrester (35) via a feed opening (25) of a feed device (20) into a combustion chamber (12) of the combustion chamber (10), wherein it is accelerated relative to the flow velocity in the flame arrester (35).

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