A nozzle structure for simulating interaction of a deep space probe engine plume with regolith

Abstract

This invention discloses a nozzle structure for simulating the interaction between a deep space probe engine plume and stellar soil, belonging to the field of deep space exploration ground simulation test technology. It includes an inlet section, a converging section, and an expanding section connected sequentially along the airflow direction. The inlet section connects to an upstream pipeline, and its inlet radius is consistent with that of the upstream pipeline to ensure stable inlet airflow. The converging section connects the inlet section and the expanding section, and its profile uses a double-circular-arc smooth transition connection to continuously accelerate the subsonic airflow during flow, reaching sonic speed at the throat. The expanding section's profile uses a circular arc tangent to a parabola to guide the sonic airflow to continuously accelerate, reaching the target supersonic Mach number at the exit. This invention can simulate engine plumes.

Description

Technical Field

[0001] This invention belongs to the field of deep space exploration ground simulation test technology, and in particular relates to a nozzle structure for simulating the interaction between the engine plume of a deep space probe and the stellar soil. Background Technology

[0002] This invention relates to the field of deep space exploration ground simulation test technology, specifically to a nozzle structure for simulating the impact of engine plume on stellar soil during the landing process of a deep space probe.

[0003] In deep space exploration missions to the Moon and Mars, probes rely on high-speed jets of air from their engines to decelerate and brake during the final stages of landing. During this process, the high-speed plume from the engine nozzle exits violently impacts the planetary surface, creating erosion pits and kicking up large amounts of dust particles, posing a serious threat to landing stability and probe safety. To faithfully reproduce this process on Earth, a nozzle capable of generating controllable supersonic airflow needs to be designed as a core component for simulating engine plumes.

[0004] However, the nozzle profile design lacks a refined match for this specific application scenario, and the selection of geometric parameters for the convergence and expansion sections lacks a systematic basis, making it difficult to simultaneously achieve structural compactness, flow quality, and precise exit parameters. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a nozzle structure that simulates the interaction between the plume of a deep space probe engine and stellar soil, thus solving the aforementioned problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a nozzle structure simulating the interaction between a deep space probe engine plume and stellar soil, comprising a nozzle, characterized in that the nozzle includes an inlet section, a converging section, and a diverging section connected sequentially along the airflow direction; the inlet section is used to connect to an upstream pipeline, and its inlet radius is consistent with that of the upstream pipeline to ensure stable inlet airflow; the converging section connects the inlet section and the diverging section, and its profile adopts a double-circular arc smooth transition connection to enable the subsonic airflow to continuously accelerate during the flow process and reach the speed of sound in the throat; The expansion section adopts a shape that is tangent to a circular arc and a parabola to guide the continuous acceleration of the sonic airflow and reach the target supersonic Mach number at the exit.

[0007] Further technical solution: The inlet section includes an outlet radius. larynx area t and the radius of the larynx , entrance radius R c nozzle inlet area cand the axial length of the inlet section ; The exit radius and export Mach number Obtain the larynx area and laryngeal radius ; The inlet radius R c Obtain the inlet area of ​​the nozzle (201) c And based on the entrance area c Get the Mach number of the entry point ; The axial length of the inlet section The value range is: 0.5 This is used to ensure a smooth connection with upstream pipelines.

[0008] Further technical solution: The nozzle is detachably and fixedly connected to the upstream pipeline of the flange, so as to facilitate replacement according to different exit Mach number requirements.

[0009] Further technical solutions: export radius The method of obtaining it is to... Import To obtain the export radius It is used to achieve the altitude range required during the landing process of deep space probes.

[0010] Further technical solution: the inlet radius c With the radius of the larynx The ratio is between 1.5 and 2.6, which is used to make the nozzle structure more compact.

[0011] Further technical solution: The convergence segment includes a convergence half-angle. axial length of the convergent segment upstream transition arc radius and downstream transition arc radius ; Determining the convergence half-angle using the extreme value boundary constraint method The range of values ​​for the convergent half-angle The value range is: 20° 40°, used to minimize the axial length of the convergence segment. ; upstream transition arc radius The value range of is: 0.6 c 0.7 cUsed to reduce the structural mass of the convergence segment; Downstream transition radius The value range is: 0.7 c 0.8 c This is used to reduce the structural mass of the convergence segment.

[0012] Further technical solution: the axial length of the convergent segment The method of obtaining it is: Import the nozzle inlet radius Rc, throat radius Rt, and convergence half-angle Tc. To obtain the reference axial length ; Reference axial length Import the To obtain the axial length of the convergence segment. .

[0013] A further technical solution: The expansion segment includes the radius of the transition arc between the expansion segment and the throat. Initial angle of the parabolic expansion segment Termination angle and the axial length of the expansion section ; The radius of the transition arc between the expansion section and the throat The range of values ​​is This is used to slowly accelerate the downstream airflow; The initial angle of the parabolic expansion segment The value range is 10° 20°, used to reduce the structural mass of the expansion section and ensure stable airflow acceleration; The termination angle The value range is 5° 10°, used to reduce performance loss caused by non-axial exhaust.

[0014] Further technical solution: axial length of the expansion section The method of obtaining it is: larynx radius Radius of the transition arc between the expansion segment and the throat and the initial angle of the parabolic extension segment Import To obtain the connection point radius at ; Connecting points radius at Initial angle of the parabolic expansion segment Export radius and termination angle Import To obtain the axial length of the expansion section .

[0015] Further technical solutions: Based on the total temperature at the nozzle exit and total pressure at the nozzle inlet Obtain the outlet static temperature and outlet static pressure This allows for verification of the outlet conditions to ensure that the outlet gas flow does not undergo condensation phase change and can achieve the optimal expansion state. The outlet static temperature The method of obtaining it is: Will =300K =2.1 and =1.4, Import To obtain the outlet static temperature ; The outlet static pressure The method of obtaining it is: Will =0.9MPa =2.1 and =1.4, Import To obtain the outlet static pressure .

[0016] Beneficial effects This invention provides a nozzle structure that simulates the interaction between the plume of a deep space probe engine and stellar soil, and has the following advantages compared with the prior art: 1. The converging section adopts a double-circular-arc smooth transition profile, which takes into account both structural compactness and flow quality. The coordinated design of the upstream and downstream transition arcs of the converging section ensures a smooth transition of airflow from the inlet to the throat, effectively reducing flow losses. When the ratio of the inlet radius to the throat radius is large (approximately 2.6 times), by setting a reasonable convergence half-angle, the axial length of the converging section is shortened to the maximum extent while ensuring stable airflow acceleration, making the nozzle structure more compact.

[0017] 2. The expansion section adopts a design where the arc and parabola are tangent, ensuring precise control of the outlet airflow parameters. The reasonable matching of the transition arc radius between the expansion section and the throat, as well as the initial and final angles of the parabolic expansion section, ensures a compact nozzle design while effectively controlling the radial velocity component of the outlet airflow, even with a small ratio of the outlet radius to the throat radius (approximately 1.3 times). This reduces performance losses caused by non-axial exhaust. Numerical simulations have verified that the average Mach number at the outlet section deviates from the theoretical design value by no more than 1%, demonstrating the accuracy and reliability of the design method.

[0018] 3. The outlet airflow condition has been rigorously verified to ensure the safety and feasibility of the test. Through systematic verification of the outlet static temperature and outlet static pressure: the outlet static temperature is much higher than the boiling point of nitrogen at atmospheric pressure, ensuring that the outlet airflow does not undergo condensation phase change within the entire operating range, avoiding deviations in aerodynamic parameters from the design state caused by phase change; the outlet static pressure matches the ambient back pressure, and the outlet airflow is in the optimal expansion state, ensuring smooth nozzle start-up and efficient operation. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0020] Figure 2 This is a diagram showing the nozzle profile parameters of the present invention.

[0021] Figure 3 This is a Mach number cloud diagram of the nozzle of the present invention.

[0022] Figure 4 This is a radial Mach number distribution diagram of the nozzle outlet of the present invention.

[0023] Figure label annotation: Nozzle 201. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0025] The specific implementation of the present invention will be described in detail below with reference to specific embodiments.

[0026] Please see Figure 1 This invention provides a nozzle structure that simulates the interaction between the plume of a deep space probe engine and stellar soil. The nozzle 201 is detachably and fixedly connected via an upstream pipeline of a flange, so as to facilitate replacement according to different exit Mach number requirements.

[0027] This embodiment uses the exit Mach number. Taking a nozzle with a specific heat ratio of 2.1 as an example, the profile design process will be explained in detail. Nitrogen gas was used as the test gas, and its specific heat ratio is... =1.4, total temperature The ambient temperature is approximately 300K. This is to enable the device to cover the landing process of deep space probes. In the height range of 90-0, the nozzle exit radius is set to... =5mm.

[0028] like Figure 2 As shown, the entire nozzle 201 is divided into three parts along the airflow direction: the inlet section, the converging section, and the diverging section.

[0029] (1) Entrance section design First, based on the isentropic relationship of adiabatic flow, establish the relationship between area and Mach number, and then use the outlet radius... =5mm and exit Mach number =2.1, the throat area is calculated. and laryngeal radius =3.67mm; The area of ​​the throat is The method of obtaining it is to set the export radius. =5mm import To obtain the nozzle exit area Increase the nozzle exit area Import, To obtain the area of ​​the larynx as ; The radius of the throat The method of obtaining it is to measure the area of ​​the larynx as follows: Import To obtain the larynx radius ; To ensure stable inlet airflow, the nozzle inlet radius... c In this case, the nozzle inlet radius is set to be consistent with the upstream pipeline radius. c =8mm, then calculate the nozzle inlet area. c And obtain the Mach number at the nozzle inlet. The value is 0.14, thus meeting the requirement that the inlet airflow Mach number should not be too high; Since the inlet section is mainly used for a smooth connection with the upstream pipeline, the axial length of the inlet section is... The range of values ​​for is: For a compact design, the axial length of the inlet section The optimal value is taken That is, 4mm.

[0030] The nozzle inlet Mach number The method for obtaining this is: the nozzle inlet radius c Equal to 8mm, import To obtain the nozzle inlet area Increase the nozzle inlet area The area of ​​the larynx is as well as =1.4, Import To obtain the nozzle inlet Mach number .

[0031] (2) Design of convergence segment Due to the nozzle inlet radius c With the radius of the larynx The ratio is between 1.5 and 2.6, with the optimal value being 2.6, which makes the nozzle structure more compact.

[0032] The value of the convergence half-angle Tc is quantified and defined by both preset geometric constraints and aerodynamic stability constraints. The reference axial length of the convergence segment... The nozzle inlet radius Rc, throat radius Rt, and convergence half-angle Tc satisfy the following geometric relationship: Given that the present invention limits the ratio of the inlet radius to the throat radius to satisfy... That is, the maximum radius difference To balance structural compactness and flow stability, this invention employs the extreme value boundary constraint method to determine... The range of values ​​for: If Then, according to the above formula, we can obtain This reference axial length will significantly increase the frictional area of ​​the converging section wall; if the convergence half-angle is too large, the airflow cannot flow tightly against the wall due to radial inertial force, resulting in a "neck" phenomenon, causing the actual effective throat area to be smaller than the geometric throat area. Therefore, the upper limit of the convergence half-angle is set at [value missing]. .

[0033] Therefore, the angle converges to half an angle. The value range is: 20° 40°, and convergent half-angle The optimal value is 40° to minimize the axial length of the convergence segment. ; The converging section profile uses a double-circular-arc smooth transition connection, with the upstream transition arc radius... The value range of is: 0.6 c 0.7 c The upstream transition arc radius The optimal value is 4.8 mm; Downstream transition radius The value range is: 0.7 c 0.8 c The downstream transition arc radius The optimal value is 5.6 mm, and the final determined axial length of the convergence segment is... Reference axial length It is twice the size of the standard, which is 12.9 mm.

[0034] (3) Expansion section design In this invention, the expansion section profile adopts a composite design of circular arc and parabola tangency. Let the throat radius be... The export radius is And satisfy To ensure the continuity of the wall curvature and reduce shock wave loss, the spreading section consists of two parts: a throat transition arc section (radius: ...). ) and the parabolic expansion segment.

[0035] The transition arc at the throat is tangent to the straight segment of the throat passage at the throat point, and tangent to the downstream parabolic curve at the junction point. Let the connection point be... The local airflow deflection angle at that location is (i.e., the initial angle of the parabolic expansion segment), then the connection point radius at Uniquely determined by the geometric relations of the arc: To prevent the supersonic airflow from generating excessive expansion waves on the concave wall surface, leading to separation, the transition arc radius is... The wall curvature radius constraint must be met: Its relationship with the radius of the larynx The ratio is (In this embodiment, a quantitative value is used to ensure that the wall pressure gradient is lower than the flow separation threshold).

[0036] With connection point The origin ( ), nozzle axial direction Axis, radial direction Establish the equation of the parabola based on the axis: Based on the tangent continuity condition and boundary constraints, the coefficients satisfy the following system of equations: Solve the above system of equations simultaneously and eliminate intermediate coefficients. The axial length of the expansion section is obtained. The parsing expression: To prevent excessive radial velocity components in the outlet airflow from causing thrust loss, the termination angle... The initial angle should be close to the axial direction (i.e., take the smallest value), while ensuring that the airflow adheres to the wall and does not separate. It needs to be less than the maximum non-separation deflection angle of supersonic flow (for the Mach number range, the critical deflection angle is approximately...). ).

[0037] To minimize the axial length of the expansion section while satisfying flow stability constraints, this invention aims to achieve the desired effect. The optimal value is obtained at the boundary of the feasible region: initial angle termination angle .Will and Substituting into the analytical expression, the axial length of the expansion segment in this embodiment is quantitatively obtained through numerical calculation: Based on the adiabatic isentropic flow relationship, the outlet state under this design parameter is verified: The outlet static temperature The method of obtaining it is: to =300K =2.1 and =1.4, Import To obtain the outlet static temperature ; The outlet static pressure The method of obtaining it is: to =0.9MPa =2.1 and =1.4, Import To obtain the outlet static pressure .

[0038] The outlet static temperature was calculated. =159K, far exceeding the boiling point of nitrogen at normal pressure (77K), ensuring that the outlet gas flow will not undergo condensation phase change; at the same time, the outlet static pressure It is approximately 0.1 MPa, which is equivalent to the back pressure of an atmospheric pressure environment, ensuring that the outlet airflow obtains the optimal expansion state and the nozzle can start smoothly.

[0039] To verify the reliability of the above design method, numerical simulations were performed on the nozzle of this embodiment. Figure 3 A Mach number cloud diagram of the nozzle interior is presented, which clearly shows that the airflow is successfully accelerated inside the nozzle and fully develops into a supersonic airflow by the time it exits.

[0040] Furthermore, the Mach number distribution along the radial (y-direction) axis at the nozzle exit position is extracted to obtain... Figure 4 The distribution curve is shown. Quantitative analysis revealed that the average Mach number of the exit section is 2.08, with a deviation of no more than 1% from the theoretical design value of 2.1. This result strongly demonstrates the accuracy and reliability of the nozzle profile design method employed in this invention.

[0041] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0042] The term "fixed connection" as used in this application refers to a connection in which parts or components are fixed without any relative movement. This includes both detachable and non-detachable connections. (1) Detachable connection: The parts are fixed together by screws, splines, wedges, etc. This type of connection can be disassembled during maintenance without damaging the parts, but the specifications of the connecting parts used must be correct (such as the length of bolts, keys, wedges) and properly tightened; (2) Non-removable connection: mainly refers to welding, riveting and tenon joints, etc. Since forging, sawing or oxygen cutting is required for disassembly during maintenance or replacement, the parts generally cannot be reused. At the same time, attention should be paid to process quality, technical inspection and remedial measures (such as correction, polishing, etc.) when connecting.

[0043] The sliding connection referred to in this application means that the component can slide along a linear trajectory, and the hinge referred to in this application means that the component can rotate along an axially constrained direction; in some cases, the sliding connection and hinge referred to in this application can also be damped, so that the component has the ability to maintain in the desired position.

[0044] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A nozzle structure simulating the interaction between a deep space probe engine plume and stellar soil, comprising a nozzle (201), characterized in that, The nozzle (201) includes an inlet section, a converging section and a diverging section connected sequentially along the airflow direction; The inlet section is used to connect to the upstream pipeline, and its inlet radius is... c It has the same radius as the upstream pipeline to ensure stable inlet airflow; The converging section connects the inlet section and the expansion section, and its profile adopts a smooth transition with double circular arcs to enable the subsonic airflow to continuously accelerate during the flow process and reach the speed of sound in the throat. The expansion section adopts a shape that is tangent to a circular arc and a parabola to guide the continuous acceleration of the sonic airflow and reach the target supersonic Mach number at the exit.

2. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil as described in claim 1, characterized in that, The inlet section includes the outlet radius. larynx area t and the radius of the larynx , entrance radius c Nozzle inlet area c and the axial length of the inlet section ; The exit radius and export Mach number Obtain the larynx area and laryngeal radius ; The inlet radius c Obtain the inlet area of ​​the nozzle (201) c And based on the entrance area c Get the Mach number of the entry point ; The axial length of the inlet section The range of values ​​for is: This is used to ensure a smooth connection with upstream pipelines.

3. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil as described in claim 1, characterized in that, The nozzle (201) is detachably fixed via the upstream pipeline of the flange, so as to facilitate replacement according to different exit Mach number requirements.

4. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil as described in claim 2, characterized in that, Export radius The method of obtaining it is to... Import To obtain the export radius It is used to achieve the altitude range required during the landing process of deep space probes.

5. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil as described in claim 2, characterized in that, The inlet radius c With the radius of the larynx The ratio is between 1.5 and 2.6, which is used to make the nozzle structure more compact.

6. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil according to claim 1, characterized in that, The convergence segment includes a convergence half-angle. axial length of the convergence segment upstream transition arc radius and downstream transition arc radius ; Determining the convergence half-angle using the extreme value boundary constraint method The range of values ​​for the convergent half-angle The value range is: 20° 40°, used to minimize the axial length of the convergence segment. ; upstream transition arc radius The value range of is: 0.6 c 0.7 c This is used to reduce the structural mass of the convergence segment; Downstream transition radius The value range is: 0.7 c 0.8 c This is used to reduce the structural mass of the convergence segment.

7. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil according to claim 1, characterized in that, The axial length of the convergence segment The method of obtaining it is: Import the nozzle inlet radius Rc, throat radius Rt, and convergence half-angle Tc. To obtain the reference axial length ; Reference axial length Import the To obtain the axial length of the convergence segment. .

8. The nozzle structure for simulating the interaction between the engine plume of a deep space probe and stellar soil according to claim 1, characterized in that, The expansion segment includes the radius of the transition arc between the expansion segment and the throat. Initial angle of the parabolic expansion segment Termination angle and the axial length of the expansion section ; The radius of the transition arc between the expansion section and the throat The range of values ​​is 0. R n R t This is used to slowly accelerate the downstream airflow; The initial angle of the parabolic expansion segment The value range is 10° 20°, used to reduce the structural mass of the expansion section and ensure stable airflow acceleration; The termination angle The value range is 5° 10°, used to reduce performance loss caused by non-axial exhaust.

9. The experimental apparatus for simulating the interaction between deep space probe engine plumes and stellar soil according to claim 1, characterized in that, The axial length of the expansion section The method of obtaining it is: larynx radius Radius of the transition arc between the expansion segment and the throat and the initial angle of the parabolic extension segment Import To obtain the connection point radius at ; Connecting points radius at Initial angle of the parabolic expansion segment Export radius and termination angle Import To obtain the axial length of the expansion section .

10. The experimental apparatus for simulating the interaction between deep space probe engine plumes and stellar soil according to claim 1, characterized in that, Based on the total temperature at the nozzle exit and total pressure at the nozzle inlet Obtain the outlet static temperature and outlet static pressure This allows for verification of the outlet conditions to ensure that the outlet gas flow does not undergo condensation phase change and can achieve the optimal expansion state. The outlet static temperature The method of obtaining it is: Will =300K =2.1 and =1.4, Import To obtain the outlet static temperature ; The outlet static pressure The method of obtaining it is: Will =0.9MPa =2.1 and =1.4, Import To obtain the outlet static pressure .

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