Direct-current impact type injector and preparation method

Abstract

The invention relates to the technical field of spacecraft propulsion systems, in particular to a direct-current impact type injector and a preparation method thereof.The direct-current impact type injector comprises an injection panel, border injection holes and a sound cavity, the injection panel is of a circular structure, the border injection holes are annularly formed in the edge area of the injection panel, and the sound cavity is located below the injection panel; the injection panel comprises injection pair units and partition grids, the injection panel is divided into a plurality of partition grids, the partition grids are regular hexagonal grids, the injection pair units are arranged in each partition grid, and the number of the partition grids is consistent with that of the injection pair units. When in use, the regular hexagon partition grid layout is adopted, so that each injection pair unit has unique position, size and injection parameter, the atomization characteristic homogenization of the traditional concentric circle layout is broken, the circumferential combustion synchronism of the combustion chamber is avoided, and the tangential acoustic resonance is effectively inhibited.

Description

Technical Field

[0001] This invention relates to the field of spacecraft propulsion system technology, and in particular to a DC impact injector and its manufacturing method. Background Technology

[0002] Space attitude and orbit control liquid rocket engines using bicomponent nitrogen tetroxide and monomethylhydrazine propellants are the primary power source for multiple orbital and attitude adjustments in satellites, spacecraft, and other spacecraft, accounting for over 90% of their propulsion. Due to the physicochemical properties of the self-igniting propellants, the engine injectors typically employ a direct-current impact design, resulting in better atomization and combustion efficiency.

[0003] According to the existing technology search, the closest existing technology is "A DC self-attacking interlocking injector and its injection hole design method", patent document CN116696600A (application number 202310627965.2). This patent relates to a dual-component attitude control thrust chamber device and its design method, specifically a DC self-impacting interlocking injector and its injection hole design method. The invention provides a DC self-impacting interlocking injector, consisting of an injection cylinder and an injection surface. The injection cylinder has an oxidizer collection chamber and a fuel collection chamber arranged radially from the center. It also includes multiple injection holes arranged radially on the injection surface. Each injection hole includes multiple oxidizer holes arranged sequentially from the inside out and corresponding to the oxidizer collection chamber, as well as multiple fuel holes and multiple cooling holes corresponding to the fuel collection chamber. The multiple oxidizer holes form multiple oxidizer self-impact pairs; the multiple fuel holes form multiple fuel self-impact pairs. This invention solves the technical problem of existing DC interlocking injectors, which, while ensuring high combustion performance, struggle to reliably cool the thrust chamber wall, especially when there are certain machining deviations in the interlocking pairs, resulting in significant temperature variations on the attitude control thrust chamber wall, thus affecting its reliable operation.

[0004] For ton-class orbital control engines, due to their large total propellant flow rate, the injection panel needs to be equipped with hundreds of DC impaction pairs to ensure injection speed and atomization effect. Due to limitations of traditional processing technology and design methods, existing injectors often arrange the injection pairs in a multi-ring, concentric circle manner.

[0005] The DC impact injector and its manufacturing method disclosed in patent document CN116696600A (application number 202310627965.2) provide a DC self-impacting interlocking injector, which consists of an injection cylinder and an injection surface. The injection cylinder has an oxidant collection chamber and a fuel collection chamber arranged radially from the center. It also includes multiple injection holes arranged radially on the injection surface. The injection holes include multiple oxidant holes arranged from the inside to the outside and corresponding to the oxidant collection chamber, as well as multiple fuel holes and multiple cooling holes corresponding to the fuel collection chamber. The multiple oxidant holes form multiple oxidant self-impact pairs, and the multiple fuel holes form multiple fuel self-impact pairs. This solves the technical problem that existing DC interlocking injectors, while ensuring high combustion performance, are unable to reliably cool the thrust chamber wall, especially when there is a certain machining deviation in the machining accuracy of the interlocking pairs, resulting in a large temperature dispersion on the thrust chamber wall, which affects its reliable operation.

[0006] This patent also employs a similar concentric circle layout, attempting to suppress unstable combustion through measures such as a steep hump distribution of spray field flow intensity, injector baffles, radial self-impact liquid phase partitioning, and acoustic cavity devices. However, this layout suffers from numerous technical drawbacks, making it difficult to avoid tangential unstable combustion problems. On one hand, the concentric circle layout results in highly similar spatial positions and geometric parameters for each injector pair, leading to uniform atomization characteristics in each injector pair unit, such as droplet size, mixing ratio distribution, and spray flow intensity. This easily induces pressure oscillations within the combustion chamber and tangential mode coupling, ultimately resulting in combustion instability. On the other hand, existing techniques that rely on passive structures such as acoustic cavities to suppress combustion instability do not address the root cause of atomization characteristic similarity in injector pair layout and parameter design. Therefore, the stability improvement effect is limited, and it may also lead to additional costs such as increased flow resistance and structural complexity. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the purpose of this invention is to provide a DC impact injector and its preparation method to alleviate the technical problem of tangentially unstable combustion caused by the multi-circle, concentric arrangement of the injectors in ton-class rail control engines.

[0008] According to the present invention, a DC impact injector includes an injection panel, side injection holes and a sound cavity. The injection panel has a circular structure, and a plurality of side injection holes are arranged in a ring around the edge region of the injection panel. The sound cavity is located below the injection panel.

[0009] The injection panel includes injection pair units and partitioned grids. The injection panel is divided into several partitioned grids, which are regular hexagonal grids. Each partitioned grid contains injection pair units. The number of partitioned grids is the same as the number of injection pair units. The size of the partitioned grids is determined by the number of grids and the size of the injection panel. The size of the injection panel is limited by the diameter of the combustion chamber and is usually positively correlated with the engine thrust.

[0010] The injection pair unit is divided into oxygen / fuel streams, and each injection pair unit has different position parameters. The injection pair units are distributed in a partitioned grid.

[0011] The injection unit includes an oxidizer collection chamber, a fuel collection chamber, an oxidizer injection hole, and a fuel injection hole. The top of both the oxidizer collection chamber and the fuel collection chamber are connected to the propellant distribution channel. The oxidizer collection chamber is connected to the combustion chamber through the oxidizer injection hole, and the fuel collection chamber is connected to the combustion chamber through the fuel injection hole.

[0012] The present invention also provides a method for manufacturing a DC impact injector, comprising the following steps:

[0013] S1: Requirements Analysis and Parameter Initialization

[0014] The overall engine parameters are input, and the thrust determines the size of the injection panel and the total propellant flow rate. The chamber pressure affects the pressure drop and atomization mode of the injection orifice, which determines the number of injection units and the use of a bicomponent auto-ignition propellant, such as NTO / MMH. The physical properties are determined: density, viscosity, and surface tension.

[0015] S2: Partitioned Grid Topology Design

[0016] By using a regular hexagonal partitioned grid, the grid can be tightly arranged and approximate a circle, with an edge gap of ≤5%, avoiding the "dead zone" problem of the traditional concentric circle layout. The spray coverage of the unit within each grid is regular hexagonal, and the overlapping areas of adjacent grids are symmetrical, which is conducive to the uniformity of downstream mixing.

[0017] S3: Injection-based unit parameter design

[0018] Propellant flows from the distribution channel into the oxygen / fuel collection chamber of the injection unit, where oxidizer enters the oxidizer collection chamber and fuel enters the fuel collection chamber, ensuring that the propellant enters the injection orifice uniformly and is ejected from the orifice at a set speed and angle, forming an impingement flow. Under pressure, the propellant is ejected from the oxygen / fuel injection orifice, meaning the oxidizer is injected from the oxidizer injection orifice and the fuel from the fuel injection orifice into the combustion chamber.

[0019] The injection unit is determined to have specific position parameters, size parameters, and injection parameters.

[0020] S4: Spray Characteristics Prediction and Parameter Correction

[0021] Based on the different jet velocities of the injection unit, the resulting spray pattern is divided into three modes, thereby optimizing the parameters. By optimizing the injection parameters, combustion is ensured to be maintained in a mixed mode (t). mix <t ign At the same time, it uses a multi-objective function to balance efficiency and stability.

[0022] S5: Spray Overlap Treatment

[0023] The parameters of the spray field are quantified using mathematical methods, and the spatial superposition effect of different sprays on the unit spray is addressed.

[0024] S6: Optimize the calculation of characteristic parameters

[0025] By constructing an objective function to integrate spray characteristic parameters, and combining optimization algorithms with engineering verification, iterative optimization of spray parameters is achieved.

[0026] Furthermore, step 3 specifically involves:

[0027] Determine the position parameters of the injection unit 12:

[0028] A coordinate system is established with the center of the nozzle panel 1, and the axis of the injector is taken as the Z-axis. The position parameters of the injection holes are obtained. The position parameters of the injection holes include the three-dimensional coordinates of the oxidizer injection hole (x1, y1, z1), the three-dimensional coordinates of the fuel injection hole (x2, y2, z2), the polar coordinates of the oxidizer injection hole (r1, γ1, z1), and the polar coordinates of the fuel injection hole (r2, γ2, z2), which satisfy the following trigonometric function relationships:

[0029]

[0030] Where r1 is the distance from the center of the oxidizer injection hole to the center of the injection hole panel 1, r2 is the distance from the center of the fuel injection hole to the center of the injection hole panel, γ1 is the circumferential angle of the oxidizer injection hole (0°-360°), and γ2 is the circumferential angle of the fuel injection hole (0°-360°).

[0031] And determine the dimensional parameters of the injection unit of the injection orifice:

[0032] The nozzle diameter d1 of the oxidizer injection orifice and the nozzle diameter d2 of the fuel injection orifice are both within the range of 0.5 to 1.5 mm.

[0033] The injection impact angle θ1 of the oxidizer injection orifice and the injection impact angle θ2 of the fuel injection orifice, the angle between the axis of the oxidizer injection orifice and the impact plane, and the range of the values ​​of θ1 and θ2 are 20°-50°.

[0034] Distance d from the exit axis 12 The distance from the exit axis to d 12 Positively correlated with nozzle diameter, satisfying:

[0035] d 12 = m(d1+d2), where m ranges from 1.5 to 2.0.

[0036] If the outlet axis is too close, it can easily cause jet interference; if it is too far, it will cause mixing delay.

[0037] The angle β between the jet and the axis of element 11, and the range of values ​​for the angle β between the jet and the axis of element 11 are expressed as follows:

[0038] β = 5n°, n = 1, 2, 3, ..., 72

[0039] This allows for the construction of a mathematical model of the injection hole location, enabling precise spatial positioning.

[0040] Determine the injection parameters for injection unit 12:

[0041] The injection parameters include the oxidizer nozzle flow rate q1, the fuel nozzle flow rate q2, the oxidizer density ρ1, the fuel density ρ2, the oxidizer injection velocity v1, and the fuel injection velocity v2. The values ​​of the oxidizer injection velocity v1 and the fuel injection velocity v2 range from 10 to 25 m / s. These parameters interact to affect the propellant injection effect.

[0042] Furthermore, step S3 derives the dimensionless injection parameter mixing ratio r from the size parameters and injection parameters of the injection unit. m And momentum ratio η:

[0043]

[0044] When η = 1, it is a symmetrical impact; when η > 1 or < 1, the direction of liquid film deflection is adjusted.

[0045] Furthermore, step S4 specifically includes:

[0046] When the oxygen / fuel jet is injected into the unit v j At low flow rates (5m / s≤v) j ≤15m / s):

[0047] After the oxygen-fuel jet impacts, a planar liquid film is formed and deflected. The calculated resultant angle δ is:

[0048]

[0049] δ is the liquid film deflection angle. When δ = 0°, it is a direct impact. When δ > 0°, it deflects towards the fuel side. When δ < 0°, it deflects towards the oxidizer side.

[0050] When the oxygen / fuel jet is injected into the unit v j At medium flow velocity (5m / s≤v) j ≤15m / s):

[0051] After the impact, oxidizer spray cones and fuel spray cones are formed separately, which overlap to form a whole spray cone. The flow flux curve along the impact direction is Gaussian distributed, with a high center and low periphery, and the mixture ratio curve gradually decreases; the flow flux curve along the spanwise direction is still Gaussian distributed, and the mixture ratio curve remains constant at 1.65.

[0052] When the oxygen / fuel jet is injected into the unit v j At high flow velocities (15m / s≤v) j ):

[0053] Oxidant and fuel atomization are fully developed turbulent modes. The spray cone is approximately a solid cone with a circular or elliptical cross-section. The flow rate at different locations is positively correlated with the height of the corresponding point on the busbar.

[0054] The engineering fitting formula for the cone angle α of a solid cone is:

[0055]

[0056] Where the orifice diameter d is fitted in mm, and the injection velocity v is fitted in m / s, d r The aperture ratio is given, and the back pressure P is in MPa. Increasing the aperture and back pressure reduces the cone angle, while increasing the flow velocity and impact angle increases the cone angle.

[0057] The engineering fitting formula for the Sothel mean diameter d32 of droplets inside a solid cone is:

[0058]

[0059] Where, p0 = 4 MPa, p D The momentum-flux ratio is expressed as

[0060]

[0061] Furthermore, step S4 obtains the dimensionless injection parameter Lupo number Ru by calculating the ratio of the diameter ratio to the momentum ratio of the oxidant to the fuel jet, expressed as:

[0062]

[0063] Where q1 is the oxidant nozzle flow rate (unit: g / s) and q2 is the fuel nozzle flow rate (unit: g / s).

[0064] Furthermore, step S5 is specifically as follows:

[0065] In the downstream z=z1 plane, which is closer to the spray panel, each spray pair is independent of the unit spray, and the parameter distribution is calculated by the unit spray model. The value at each point is determined by the distribution density function.

[0066] In the downstream plane (z = z2), which is far from the spray panel, spray overlaps. Parameter calculation rules:

[0067] For scalars, summation is used;

[0068] For statistical values, the geometric mean with flow rate as the weight is used, as shown in the formula:

[0069]

[0070] Calculate the uniformity of characteristic parameters:

[0071]

[0072] Where σ represents the uniformity of the characteristic parameters of the corresponding cross section, with a value closer to 1 indicating greater uniformity and a larger value indicating greater non-uniformity, and f(x,y,z) represents the distribution function of the characteristic parameters in the corresponding cross section. The value of the characteristic parameter is used to represent the average value of the corresponding cross section, S is used to represent the total area of ​​the corresponding cross section, and ds is used to represent the area integral.

[0073] At a downstream location far from the injection surface z = z0, the mixing time or ignition delay time of the propellant oxygen-fuel spray and components are not uniform in characteristic parameters. This indicates that the degree of oxygen-fuel mixing or chemical reaction between adjacent injections is large, and combustion instability is less likely to occur.

[0074] Furthermore, step S6 is specifically as follows:

[0075] By integrating the uniformity and average value of characteristic parameters, a multi-objective function is formed. With corresponding weight values, the different importance of each parameter is reflected in the multi-objective function optimization, which comprehensively reflects the state and performance of the spray and provides data support for subsequent optimization.

[0076] Based on these characteristic parameters, a multi-objective function is established, with the following form:

[0077] σ(d,θ,v,…,q)=λ1σ(q)+λ2σ(SMD)+λ3σ(p)+λ4σ(r m )+λ5σ(p D )+λ6σ(Ru)+λ7σ(t mix )+λ8σ(t ign )

[0078] Wherein, σ(q) represents mass flow rate uniformity, the uniformity of propellant spray distribution across the combustion chamber cross-section; higher uniformity results in higher combustion efficiency. σ(SMD) represents droplet size uniformity, the consistency of droplet size distribution; moderate non-uniformity can suppress combustion instability. σ(p) represents spray flow intensity non-uniformity, the spatial distribution difference of spray momentum; higher non-uniformity makes it less likely to induce acoustic oscillations. σ(r) m ) represents the uniformity of the mixing ratio, specifically the uniformity of the mass flow rate ratio of oxidant to fuel. Higher uniformity indicates more thorough mixing. σ(p) D The momentum flux ratio uniformity is represented by σ(Ru), which breaks the symmetry of the combustion process and suppresses unstable modes by allowing spatial differences in momentum flux. σ(Ru) represents the Lupo number uniformity, the consistency of atomization effect; the closer the Lupo number is to 1 and the more uniform its distribution, the higher the atomization quality. mix ) represents the mixing time non-uniformity, the difference in mixing time between adjacent injection units. Non-uniformity can prevent combustion synchronization. σ(t) ign ) represents the ignition delay non-uniformity, the difference in the onset time of the chemical reaction, which inhibits the synchronous propagation of the combustion wave to enhance stability. λ i Let represent the importance weight of the i-th feature parameter, i = 1, 2, ..., 8.

[0079] The present invention also provides a rocket engine, characterized in that it includes the aforementioned DC impact injector.

[0080] The present invention also provides a rocket, characterized in that it includes the aforementioned rocket engine, wherein the rocket engine can be a regenerative cooling rocket engine.

[0081] Compared with the prior art, the present invention has the following beneficial effects:

[0082] When used, this invention employs a regular hexagonal partitioned grid layout, giving each injection unit a unique position, size, and injection parameters. This breaks the homogeneity of atomization characteristics in traditional concentric circle layouts, avoids circumferential combustion synchronization in the combustion chamber, and effectively suppresses tangential acoustic resonance.

[0083] When used in this invention, multi-objective function optimization is employed to allow for non-uniform distribution of parameters such as droplet size and spray intensity (e.g., parameter differences between the edge and center regions), thereby disrupting the regular propagation of combustion waves and reducing the risk of pressure oscillations. Attached Figure Description

[0084] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0085] Figure 1 This is a schematic diagram of a DC impact injector provided in an embodiment of the present invention;

[0086] Figure 2 A schematic diagram of the injection panel of a DC impact injector provided in an embodiment of the present invention;

[0087] Figure 3 This is a schematic diagram of the injection pair unit position distribution of a DC impact injector provided in an embodiment of the present invention;

[0088] Figure 4 A schematic diagram of the injection unit size parameters of the DC impact injector provided in an embodiment of the present invention;

[0089] Figure 5 A schematic diagram of the combined angle and divergence angle of the planar liquid film or liquid fan formed by the impact of two jets in the injection unit of the DC impact injector provided in the embodiment of the present invention;

[0090] Figure 6 A schematic diagram of the spray cone, flow rate curve, and mixing ratio curve formed by the impact of two jets in the spray unit of the DC impact injector provided in an embodiment of the present invention;

[0091] Figure 7 A schematic diagram of the jetting effect on the unit droplet collision and breakup and flow rate curves of the DC impact injector provided in an embodiment of the present invention;

[0092] Figure 8 A schematic diagram of a solid spray cone formed by the impact atomization of two jets in the spray unit of the DC impact injector provided in an embodiment of the present invention;

[0093] Figure 9 A schematic diagram of the mixing time and ignition delay time of the two jets impacting and atomizing in the injection unit of the DC impact injector provided in an embodiment of the present invention;

[0094] Figure 10 This is a schematic diagram of the parameter spatial distribution of the spray units of the DC impact injector provided in the embodiment of the present invention, showing the plane close to the injection surface downstream of the injection unit where the sprays do not overlap.

[0095] Figure 11 This is a schematic diagram of the parameter spatial distribution of the spray overlap of the spray unit on a plane far from the spray surface downstream of the DC impact injector provided in the embodiment of the present invention.

[0096] Figure 12 This is a schematic diagram showing the distribution of spray mixing time or ignition delay time of a downstream section of a DC impact injector provided in an embodiment of the present invention.

[0097] The diagram shows:

[0098]

[0099] Sideview represents the side view; Frontview represents the front view. Detailed Implementation

[0100] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0101] like Figure 1 As shown, the present invention provides a DC impact injector, including an injection panel 1, side injection holes 2 and a sound cavity 3. The injection panel 1 has a circular structure, and multiple side injection holes 2 are arranged in a ring around the edge area of ​​the injection panel 1. The injection panel 1 is used to adjust the fuel distribution at the edge of the combustion chamber. The sound cavity 3 is located below the injection panel 1 and is used to suppress combustion instability.

[0102] like Figure 2 As shown, the spray panel 1 includes spray pair units 11 and partition grids 12. The spray panel 1 is divided into several partition grids 12. The partition grids 12 are divided into regular hexagons. Compared with equilateral triangles and squares, regular hexagons have the shortest total length of sides when covering the same area, which makes the space utilization rate the highest and can better fit the edge of the circular spray surface.

[0103] Each partition grid 12 contains injection pair units 11. The number of partition grids 12 is the same as the number of injection pair units 11. The size of the partition grid 12 is determined by the number of grids and the size of the injection panel 1. The size of the injection panel 1 is limited by the combustion chamber diameter and is generally positively correlated with the engine thrust and negatively correlated with the chamber pressure.

[0104] Operating Condition 1: Engine with a thrust of 5kN and a chamber pressure of 1MPa, the size of injection panel 1 matches the diameter of the combustion chamber, the partition grid 12 has 180 units, and the injection pair unit 11 has 180 groups.

[0105] Operating Condition 2: For an engine with a thrust of 10kN and a chamber pressure of 4MPa, although the chamber pressure increases, due to the positive correlation between thrust and injection panel size, the partition grid 12 has 180 units and the injection pair unit 11 has 180 groups.

[0106] Operating Condition 3: For an engine with a thrust of 15kN and a chamber pressure of 1MPa, due to the increased thrust, it is necessary to expand the area of ​​the injection panel 1, increase the number of partition grids 12 to 280, and increase the number of injection pair units 11 to 280 to ensure propellant flow rate and atomization uniformity.

[0107] like Figure 3As shown, the injection pair unit 11 is divided into oxygen / fuel paths, and each injection pair unit 11 has different position parameters. The injection pair units 11 are distributed according to the partition grid 12.

[0108] like Figure 4 As shown, each injection unit 11 includes an oxidizer collection chamber 41, a fuel collection chamber 42, an oxidizer injection hole 51, and a fuel injection hole 52. The top of the oxidizer collection chamber 41 and the top of the fuel collection chamber 42 are connected to the propellant distribution channel. The oxidizer collection chamber 41 is connected to the combustion chamber through the oxidizer injection hole 51, and the fuel collection chamber 42 is connected to the combustion chamber through the fuel injection hole 52.

[0109] The present invention also provides a method for manufacturing a DC impact injector, comprising the following steps:

[0110] S1: Requirements Analysis and Parameter Initialization

[0111] The overall engine parameters are input, and the thrust determines the size of the injection panel and the total propellant flow rate. The chamber pressure affects the pressure drop and atomization mode of the injection orifice, which determines the number of injection units and the use of a bicomponent auto-ignition propellant, such as NTO / MMH. The physical properties are determined: density, viscosity, and surface tension.

[0112] S2: Partitioned Grid Topology Design

[0113] The hexagonal grid 12 can be closely arranged and approximate a circle with an edge gap of ≤5%, avoiding the "dead zone" problem of traditional concentric circle layout. The spray coverage of the unit within each grid is hexagonal, and the overlapping area of ​​adjacent grids is symmetrical, which is conducive to the uniformity of downstream mixing.

[0114] S3: Injection-based unit parameter design

[0115] Propellant flows from the distribution channel into the oxygen / fuel collection chamber of injection unit 11, with oxidizer entering oxidizer collection chamber 41 and fuel entering fuel collection chamber 42. This process provides a stable propellant source for subsequent injections, and the collection chambers act as converging and buffering chambers to ensure that the propellant enters the injection orifice uniformly and is ejected at a set speed and angle, forming an impingement flow. Under pressure, the propellant is ejected from the oxygen / fuel injection orifice, i.e., oxidizer from oxidizer injection orifice 51 and fuel from fuel injection orifice 52 into the combustion chamber.

[0116] During the injection process, the injection unit 12 has specific position parameters, size parameters and injection parameters.

[0117] like Figure 3As shown, a coordinate system is established with the center of the nozzle panel 1, and the axis of the injector is taken as the Z-axis to obtain the nozzle position parameters. The nozzle position parameters include the three-dimensional coordinates of the oxidizer nozzle 51 as (x1, y1, z1) and the three-dimensional coordinates of the fuel nozzle 52 as (x2, y2, z2). The polar coordinates of the oxidizer nozzle 51 are (r1, γ1, z1) and the polar coordinates of the fuel nozzle 52 are (r2, γ2, z2), which satisfy the trigonometric function relationship:

[0118]

[0119] Where r1 is the distance from the center of the oxidizer injection hole 51 to the center of the injection hole panel 1, r2 is the distance from the center of the fuel injection hole 52 to the center of the injection hole panel 1, γ1 is the circumferential angle of the oxidizer injection hole 51 (0°-360°), and γ2 is the circumferential angle of the fuel injection hole 52 (0°-360°).

[0120] The angle β between the jet and the axis of unit 11, and the range of values ​​for the angle β between the jet and the axis of unit 11 are expressed as follows:

[0121] β = 5n°, n = 1, 2, 3, ..., 72

[0122] This allows for the construction of a mathematical model of the injection hole location, enabling precise spatial positioning.

[0123] like Figure 4 As shown, the injection orifice size parameters include:

[0124] The nozzle diameter d1 of the oxidizer injection hole 51 and the nozzle diameter d2 of the fuel injection hole 52 are in the range of 0.5 to 1.5 mm.

[0125] The injection impact angle θ1 of the oxidizer injection hole 51 and the injection impact angle θ2 of the fuel injection hole 52, the angle between the axis of the oxidizer injection hole and the impact plane is θ1 and the angle between the axis of the fuel injection hole and the impact plane is θ2, and the range of values ​​is 20°-50°.

[0126] Distance d from the exit axis 12 The distance from the exit axis to d 12 Positively correlated with nozzle diameter, satisfying:

[0127] d 12 = m(d1+d2), where m ranges from 1.5 to 2.0.

[0128] If the outlet axis is too close, it can cause jet interference; if it is too far, it will cause mixing delay.

[0129] The injection parameters include the oxidizer nozzle flow rate q1, the fuel nozzle flow rate q2, the oxidizer density ρ1, the fuel density ρ2, the oxidizer injection velocity v1, and the fuel injection velocity v2. The values ​​of the oxidizer injection velocity v1 and the fuel injection velocity v2 range from 10 to 25 m / s. These parameters interact to affect the propellant injection effect.

[0130] The dimensionless jet parameter mixing ratio r is derived from the size parameters and jet parameters of the jet unit 11. m And momentum ratio η:

[0131]

[0132] When η = 1, it is a symmetrical impact; when η > 1 or < 1, the direction of liquid film deflection is adjusted.

[0133] S4: Spray Characteristics Prediction and Parameter Correction

[0134] Based on the different jet velocities of the jet into unit 11, the resulting spray pattern is divided into three modes, thereby optimizing the parameters:

[0135] like Figure 6 As shown, when the oxygen / fuel jet v is injected into unit 11 j At low flow rates (5m / s≤v) j ≤15m / s):

[0136] After the oxygen-fuel jet impacts, a planar liquid film is formed and deflected. The calculated resultant angle δ is:

[0137]

[0138] δ is the liquid film deflection angle. When δ = 0°, it is a direct impact. When δ > 0°, it deflects towards the fuel side. When δ < 0°, it deflects towards the oxidizer side.

[0139] The angle of the liquid film or liquid fan is α, which is related to the impact angle θ and the velocity v, and can be obtained through cold flow tests.

[0140] At this point, the formation and deflection of the liquid film have a significant impact on the initial distribution of the propellant, determining the subsequent mixing and combustion initiation state.

[0141] like Figure 7 As shown, when the oxygen / fuel jet v is injected into unit 11 j At medium flow velocity (5m / s≤v) j ≤15m / s):

[0142] After the impact, oxidizer spray cones and fuel spray cones are formed separately, which overlap to form a whole spray cone. The flow flux curve along the impact direction is Gaussian distributed, with a high center and low periphery, and the mixture ratio curve gradually decreases; the flow flux curve along the spanwise direction is still Gaussian distributed, and the mixture ratio curve remains constant at 1.65.

[0143] The formation and distribution characteristics of this spray cone allow the propellant to mix further during this stage, creating more favorable conditions for combustion.

[0144] like Figure 8 As shown, when the oxygen / fuel jet v is injected into unit 11 j At high flow velocities (15m / s≤v) j ):

[0145] Oxidant and fuel atomization are fully developed turbulent modes. The spray cone is approximately a solid cone with a circular or elliptical cross-section. The flow rate at different locations is positively correlated with the height of the corresponding point on the busbar.

[0146] The engineering fitting formula for the cone angle α of a solid cone is:

[0147]

[0148] Where the orifice diameter d is fitted in mm, and the injection velocity v is fitted in m / s, d r The aperture ratio is given, and the back pressure P is in MPa. Increasing the aperture and back pressure reduces the cone angle, while increasing the flow velocity and impact angle increases the cone angle.

[0149] Sothel mean diameter d of droplets inside a solid cone 32 The engineering fitting formula is:

[0150]

[0151] Where, p0 = 4 MPa, p D The momentum-flux ratio is expressed as

[0152]

[0153] At high flow rates, the propellant atomizes and mixes more thoroughly, which plays a crucial role in improving combustion efficiency.

[0154] The Lupo number Ru is obtained. The Lupo number Ru is defined as the ratio of the diameter ratio to the momentum ratio of the oxidant and fuel jets, characterizing the atomization effect after the collision of the two jets, and is expressed as:

[0155]

[0156] Where q1 is the oxidant nozzle flow rate (unit: g / s) and q2 is the fuel nozzle flow rate (unit: g / s).

[0157] like Figure 9 As shown, the mixing time t of the oxidizer fuel jet impact. mix and ignition delay time t ign Determined by injection parameters and physical property parameters, when t mix <t ign At this time, combustion is in a mixed mode, with good mixing and high combustion efficiency; when t mix >t ign When combustion transitions to a reactive flow separation mode, both combustion efficiency and stability are low.

[0158] Therefore, it is necessary to optimize the injection parameters to ensure that combustion is maintained in a mixed mode (t). mix <t ign At the same time, multi-objective functions are used to balance efficiency and stability (such as allowing some parameters to be non-uniform to suppress oscillations).

[0159] Based on the physical properties of the oxidant nitrogen tetroxide (NTO) and the fuel monomethylhydrazine (MMH), and with the Lupo number Ru and the synthesis angle δ as design targets, the optimal injection pair unit design and operating parameters are given:

[0160] Table 1. Physical properties of oxidizers and fuels

[0161] <![CDATA[Density g / cm 3 > Viscosity Pa·s Surface tension N / m Nitrogen tetroxide 1.45 4.16E-04 2.65E-02 Monomethylhydrazine 0.87 8.50E-04 3.35E-02

[0162] Table 2 Preferred Scheme for Injection Unit

[0163] Option 1 Option 2 Option 3 Option 4 Option 5 Option Six <![CDATA[d1(mm)]]> 0.8 0.8 1.2 0.8 0.6 0.8 <![CDATA[d2(mm)]]> 0.6 0.6 0.9 0.6 0.5 0.7 <![CDATA[θ1(°)]]> 30 25 30 30 30 45 <![CDATA[θ2(°)]]> 45 35 45 45 30 30 <![CDATA[v1(m / s)]]> 15 15 15 10 12 12 <![CDATA[v2(m / s)]]> 20 20 20 15 18 18 <![CDATA[q1(g / s)]]> 10.93 10.93 24.60 7.29 4.92 8.75 <![CDATA[q2(g / s)]]> 4.92 4.92 11.07 3.69 3.07 6.03 rm 2.22 2.22 2.22 1.98 1.60 1.45 η 1.67 1.67 1.67 1.32 1.07 0.97 Ru 3.47 3.47 3.47 2.74 2.47 2.35 δ(°) 3.36 3.21 3.36 -1.51 1.07 6.77

[0164] Comparative Example 1

[0165] Keeping the orifice diameter and flow velocity constant, only changing the injection angle can generate new schemes (such as Scheme 1 and Scheme 2). The resultant momentum angle changes, and the spatial distribution of the downstream spray changes. For a regular hexagonal partitioned grid, in order to achieve a uniform spatial distribution of the downstream spray, the resultant momentum angle should be as small as possible, unlike the traditional concentric circle sprays which are staggered and require a larger resultant momentum angle so that the spray fills the middle part of adjacent concentric circles.

[0166] Comparative Example 2

[0167] By keeping the injection angle and flow rate constant and proportionally scaling the orifice diameter, new schemes (such as Scheme 1 and Scheme 3) can be obtained, resulting in changes in the downstream spray flow rate and particle size. Among these changes, different propellant flow intensities and spray evaporation times play an important role in suppressing unstable combustion.

[0168] Comparative Example 3

[0169] By keeping the orifice diameter and injection angle constant and adjusting the injection speed, new solutions (such as Scheme 1 and Scheme 4) can be obtained. The mixing distance of the downstream spray changes, which plays an important role in suppressing unstable combustion.

[0170] By combining and adjusting the design and operating parameters, new injection unit schemes (such as Scheme 5 and Scheme 6) can be obtained.

[0171] S5: Spray Overlap Treatment

[0172] The parameters of the spray field are quantified using mathematical methods, and the spatial superposition effect of different sprays on the spray of Unit 11 is handled.

[0173] like Figure 10 As shown, in the z=z1 plane downstream, which is closer to the spray panel, the sprays of different spray pairs do not overlap, and the parameter distribution in the plane has spatial distribution characteristics. The parameter value at each point is obtained by the zero or distribution density function.

[0174] like Figure 11 As shown, in the z = z2 plane downstream, which is far from the spray panel, the spray overlaps. For scalar quantities such as mass flow rate and droplet number, summation is used for calculation; for statistical and dimensionless values ​​such as particle size, mixing ratio, and Lupo number, the geometric mean with flow rate as the weight is used.

[0175] like Figure 12 As shown, at a downstream position far from the injection surface z = z0, the characteristic parameters of the mixing time or ignition delay time of the propellant oxygen-fuel spray and components are not uniform, indicating that the degree of oxygen-fuel mixing or chemical reaction of adjacent injections is large, and combustion instability is less likely to occur.

[0176] This method allows for accurate calculation and analysis of parameters in the overlapping spray area, further optimizing the spraying effect.

[0177] The propellant spray characteristic parameters of a downstream cross section (e.g., the z = z2 plane) are selected as the optimization objective. The mean value for the entire plane is first obtained by integration followed by averaging.

[0178]

[0179] The formula for calculating the uniformity of the characteristic parameter can be expressed as:

[0180]

[0181] Where σ represents the uniformity of the characteristic parameters of the corresponding cross section, with a value closer to 1 indicating greater uniformity and a larger value indicating greater non-uniformity, and f(x,y,z) represents the distribution function of the characteristic parameters in the corresponding cross section. The value of the characteristic parameter is used to represent the average value of the corresponding cross section, S is used to represent the total area of ​​the corresponding cross section, and ds is used to represent the area integral.

[0182] S6: Optimize the calculation of characteristic parameters

[0183] By constructing an objective function to integrate spray characteristic parameters, and combining optimization algorithms with engineering verification, iterative optimization of spray parameters is achieved.

[0184] By integrating the uniformity and average value of characteristic parameters, a multi-objective function is formed. With corresponding weight values, the different importance of each parameter is reflected in the multi-objective function optimization, which comprehensively reflects the state and performance of the spray and provides data support for subsequent optimization.

[0185] Based on these characteristic parameters, a multi-objective function is established, with the following form:

[0186] σ(d,θ,v,…,q)=λ1σ(q)+λ2σ(SMD)+λ3σ(p)+λ4σ(r m )+λ5σ(p D )+λ6σ(Ru)+λ7σ(t mix )+λ8σ(t ign )

[0187] Wherein, σ(q) represents mass flow rate uniformity, the uniformity of propellant spray distribution across the combustion chamber cross-section; higher uniformity results in higher combustion efficiency. σ(SMD) represents droplet size uniformity, the consistency of droplet size distribution; moderate non-uniformity can suppress combustion instability. σ(p) represents spray flow intensity non-uniformity, the spatial distribution difference of spray momentum; higher non-uniformity makes it less likely to induce acoustic oscillations. σ(r) m ) represents the uniformity of the mixing ratio, specifically the uniformity of the mass flow rate ratio of oxidant to fuel. Higher uniformity indicates more thorough mixing. σ(p) D The momentum flux ratio uniformity is represented by σ(Ru), which breaks the symmetry of the combustion process and suppresses unstable modes by allowing spatial differences in momentum flux. σ(Ru) represents the Lupo number uniformity, the consistency of atomization effect; the closer the Lupo number is to 1 and the more uniform its distribution, the higher the atomization quality. mix ) represents the mixing time non-uniformity, the difference in mixing time between adjacent injection units. Non-uniformity can prevent combustion synchronization. σ(t) ign ) represents the ignition delay non-uniformity, the difference in the onset time of the chemical reaction, which inhibits the synchronous propagation of the combustion wave to enhance stability. λ i Let represent the importance weight of the i-th feature parameter, i = 1, 2, ..., 8.

[0188] The present invention also provides a rocket engine, including the aforementioned DC impact injector. The technical advantages and effects achieved by the rocket engine provided in this embodiment also include the technical advantages and effects achieved by the DC impact injector, which will not be repeated here.

[0189] The present invention also provides a rocket, including the aforementioned rocket engine, wherein the rocket engine can be a regenerative cooling rocket engine. The technical advantages and effects achieved by the rocket provided in this embodiment also include the technical advantages and effects achieved by the rocket engine, which will not be repeated here.

[0190] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0191] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A DC impact injector, characterized in that, It includes a spray panel (1), side spray holes (2) and a sound cavity (3). The spray panel (1) has a circular structure. Multiple side spray holes (2) are arranged in a ring on the edge area of ​​the spray panel (1). The sound cavity (3) is located below the spray panel (1). The injection panel (1) includes injection pair units (11) and partition grids (12). The injection panel (1) is divided into several partition grids (12). The partition grids are regular hexagonal grids. Each partition grid (12) is provided with an injection pair unit (11). The number of partition grids (12) is the same as the number of injection pair units (11). The size of the partition grid (12) is determined by the number of grids and the size of the injection panel (1). The size of the injection panel (1) is limited by the diameter of the combustion chamber and is usually positively correlated with the engine thrust. The injection pair unit (11) is divided into oxygen / fuel two paths. Each injection pair unit (11) has different position parameters. The injection pair units (11) are distributed according to the partition grid (12). The injection unit (11) includes an oxidizer collection chamber (41), a fuel collection chamber (42), an oxidizer injection hole (51), and a fuel injection hole (52). The top of the oxidizer collection chamber (41) and the top of the fuel collection chamber (42) are both connected to the propellant distribution channel. The oxidizer collection chamber (41) is connected to the combustion chamber through the oxidizer injection hole (51), and the fuel collection chamber (42) is connected to the combustion chamber through the fuel injection hole (52).

2. A method for preparing the DC impact injector according to claim 1, characterized in that, Includes the following steps: S1: Requirements Analysis and Parameter Initialization Input the overall engine parameters, determine the injection panel size and total propellant flow rate through thrust, the chamber pressure affects the injection hole pressure drop and atomization mode, determine the number of injection pair units and the use of bicomponent auto-ignition propellant, and determine the physical properties: density, viscosity, and surface tension. S2: Partitioned Grid Topology Design Using a regular hexagonal partitioned grid (12), the grid can be closely arranged and approximate a circle with an edge gap of ≤5%, avoiding the "dead zone" problem of the traditional concentric circle layout. The spray coverage of unit 11 within each grid is regular hexagonal, and the overlapping area of ​​adjacent grids is symmetrical, which is beneficial to the downstream mixing uniformity. S3: Injection-based unit parameter design The propellant flows from the distribution channel into the oxygen / fuel collection chamber of the injection unit (11), where the oxidizer enters the oxidizer collection chamber (41) and the fuel enters the fuel collection chamber (42), ensuring that the propellant can enter the injection hole evenly and be ejected through the injection hole at a set speed and angle to form an impingement flow. Under pressure, the propellant is ejected from the oxygen / fuel injection hole, that is, the oxidizer is injected into the combustion chamber from the oxidizer injection hole (51) and the fuel is injected into the combustion chamber from the fuel injection hole (52); The injection unit 12 is determined to have specific position parameters, size parameters, and injection parameters; S4: Spray Characteristics Prediction and Parameter Correction Based on the different jet velocities of the injection unit (11), the resulting spray patterns are divided into three modes, thereby optimizing the parameters. By optimizing the injection parameters, combustion is ensured to be maintained in the mixed mode (t). mix <t ign At the same time, it utilizes a multi-objective function to balance efficiency and stability; S5: Spray Overlap Treatment The parameters of the spray field are quantified by mathematical methods and the spatial superposition effect of different sprays on the unit (11) spray is processed. S6: Optimize the calculation of characteristic parameters By constructing an objective function to integrate spray characteristic parameters, and combining optimization algorithms with engineering verification, iterative optimization of spray parameters is achieved.

3. A method for preparing the DC impact injector according to claim 2, characterized in that, Step 3 specifically involves: Determine the position parameters of the injection unit (12): A coordinate system is established with the center of the nozzle panel 1 as the center and the axis of the injector as the Z-axis. The position parameters of the injection holes are obtained. The position parameters of the injection holes include the three-dimensional coordinates of the oxidizer injection hole (51) as (x1, y1, z1) and the three-dimensional coordinates of the fuel injection hole (52) as (x2, y2, z2). The polar coordinates of the oxidizer injection hole (51) are (r1, γ1, z1) and the polar coordinates of the fuel injection hole (52) are (r2, γ2, z2), which satisfy the trigonometric function relationship: Where r1 is the distance from the center of the oxidant injection hole (51) to the center of the injection hole panel (1), r2 is the distance from the center of the fuel injection hole (52) to the center of the injection hole panel (1), γ1 is the circumferential angle of the oxidant injection hole (51) (0°-360°), and γ2 is the circumferential angle of the fuel injection hole (52) (0°-360°). And determine the dimensional parameters of the injection unit (12) of the injection orifice: The nozzle diameter d1 of the oxidant injection hole (51) and the nozzle diameter d2 of the fuel injection hole (52) are in the range of 0.5 to 1.5 mm. The injection impact angle θ1 of the oxidant injection hole (51) and the injection impact angle θ2 of the fuel injection hole (52) are 20°-50°. Distance d from the exit axis 12 The distance from the exit axis to d 12 Positively correlated with nozzle diameter, satisfying: d 12 = m(d1+d2), where m ranges from 1.5 to 2.

0. If the outlet axis is too close, it can easily cause jet interference; if it is too far, it will cause mixing delay. The angle β of the jet to the axis of unit (11) is expressed as β = 5n°, n = 1, 2, 3, ..., 72. This allows for the construction of a mathematical model of the injection hole location, enabling precise spatial positioning. Determine the injection parameters for injection unit (12): The injection parameters include the oxidizer nozzle flow rate q1, the fuel nozzle flow rate q2, the oxidizer density ρ1, the fuel density ρ2, the oxidizer injection velocity v1, and the fuel injection velocity v2. The values ​​of the oxidizer injection velocity v1 and the fuel injection velocity v2 range from 10 to 25 m / s. These parameters interact to affect the propellant injection effect.

4. The method for preparing a DC impact injector according to claim 3, characterized in that, Step S3 derives the dimensionless injection parameter mixing ratio r from the size parameters and injection parameters of the injection unit (11). m And momentum ratio η: When η = 1, it is a symmetrical impact; when η > 1 or < 1, the direction of liquid film deflection is adjusted.

5. The method for preparing a DC impact injector according to claim 2, characterized in that, Step S4 specifically involves: When the oxygen / fuel jet of the injection unit (11) is at a low velocity (5m / s≤v) j ≤15m / s): After the oxygen-fuel jet impacts, a planar liquid film is formed and deflected. The calculated resultant angle δ is: δ is the liquid film deflection angle. When δ = 0°, it is a direct impact. When δ > 0°, it deflects towards the fuel side. When δ < 0°, it deflects towards the oxidizer side. When the oxygen / fuel jet of the injection unit (11) is at a medium velocity (5m / s≤v) j ≤15m / s): After the impact, an oxidizer spray cone and a fuel spray cone are formed respectively, which overlap to form an integral spray cone; the flow flux curve along the impact direction is Gaussian distributed, with a high center and a low periphery, and the mixture ratio curve gradually decreases; the flow flux curve along the spanwise direction is still Gaussian distributed, and the mixture ratio curve remains constant at 1.

65. When the oxygen / fuel jet of the injection unit (11) is at a high velocity (15m / s≤v) j ): Oxidant and fuel atomization are fully developed turbulent modes. The spray cone is approximately a solid cone with a circular or elliptical cross-section. The flow rate at different locations is positively correlated with the height of the corresponding point on the generatrix. The engineering fitting formula for the cone angle α of a solid cone is: Where the orifice diameter d is fitted in mm, and the injection velocity v is fitted in m / s, d r The aperture ratio is given, and the back pressure P is in MPa. Increasing the aperture and back pressure reduces the cone angle, while increasing the flow velocity and impact angle increases the cone angle. Sothel mean diameter d of droplets inside a solid cone 32 The engineering fitting formula is: Where, p0 = 4 MPa, p D The momentum-flux ratio is expressed as 6. The method for preparing a DC impact injector according to claim 2, characterized in that, Step S4 obtains the dimensionless injection parameter Lupo number Ru by calculating the ratio of the diameter ratio to the momentum ratio of the oxidizer and fuel jets, expressed as: Where q1 is the oxidant nozzle flow rate (unit: g / s) and q2 is the fuel nozzle flow rate (unit: g / s).

7. The method for preparing a DC impact injector according to claim 2, characterized in that, Step S5 is as follows: In the downstream z=z1 plane, which is closer to the spray panel, each spray pair is independent of the unit spray, and the parameter distribution is calculated by the unit spray model. The value at each point is determined by the distribution density function. In the downstream plane (z = z2), which is far from the spray panel, spray overlaps. Parameter calculation rules: For scalars, summation is used; For statistical values, the geometric mean with flow rate as the weight is used, as shown in the formula: Calculate the uniformity of characteristic parameters: Where σ represents the uniformity of the characteristic parameters of the corresponding cross section, with a value closer to 1 indicating greater uniformity and a larger value indicating greater non-uniformity, and f(x,y,z) represents the distribution function of the characteristic parameters in the corresponding cross section. The value of the characteristic parameter is used to represent the average value of the corresponding cross section, S is used to represent the total area of ​​the corresponding cross section, and ds is used to represent the area integral. At a downstream location far from the injection surface z = z0, the mixing time or ignition delay time of the propellant oxygen-fuel spray and components are not uniform in characteristic parameters. This indicates that the degree of oxygen-fuel mixing or chemical reaction between adjacent injections is large, and combustion instability is less likely to occur.

8. The method for preparing a DC impact injector according to claim 2, characterized in that, Step S6 is as follows: By integrating the uniformity and average value of characteristic parameters, a multi-objective function is formed. With corresponding weight values, the different importance of each parameter is reflected in the multi-objective function optimization, which comprehensively reflects the state and performance of the spray and provides data support for subsequent optimization. Based on these characteristic parameters, a multi-objective function is established, with the following form: σ(d,θ,v,…,q)=λ1σ(q)+λ2σ(SMD)+λ3σ(p)+λ4σ(r m )+λ5σ(p D )+λ6σ(Ru)+λ7σ(t mix )+λ8σ(t ign ) Wherein, σ(q) represents mass flow rate uniformity, the uniformity of propellant spray distribution across the combustion chamber cross-section; higher uniformity results in higher combustion efficiency. σ(SMD) represents droplet size uniformity, the consistency of droplet size distribution; moderate non-uniformity can suppress combustion instability. σ(p) represents spray flow intensity non-uniformity, the spatial distribution difference of spray momentum; higher non-uniformity makes it less likely to induce acoustic oscillations. σ(r) m ) represents the uniformity of the mixing ratio, specifically the uniformity of the mass flow rate ratio of oxidant to fuel. Higher uniformity indicates more thorough mixing. σ(p) D The momentum flux ratio uniformity is represented by σ(Ru), which breaks the symmetry of the combustion process and suppresses unstable modes by allowing spatial differences in momentum flux. σ(Ru) represents the Lupo number uniformity, the consistency of atomization effect; the closer the Lupo number is to 1 and the more uniform its distribution, the higher the atomization quality. mix ) represents the mixing time non-uniformity, the difference in mixing time between adjacent injection units. Non-uniformity can prevent combustion synchronization. σ(t) ign ) represents the ignition delay non-uniformity, the difference in the onset time of the chemical reaction, which inhibits the synchronous propagation of the combustion wave to enhance stability. λ i Let represent the importance weight of the i-th feature parameter, i = 1, 2, ..., 8.

9. A rocket engine, characterized in that, Includes the DC impact injector as described in claim 1.

10. A rocket, characterized in that, Including the rocket engine as described in claim 9.

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