Ablation examination structure for expansion section of solid rocket engine nozzle

Abstract

The utility model relates to a solid rocket engine nozzle expansion section ablation examination structure. The expansion section is composed of an ablation examination sample block and a low-cost trepanning expansion section, the ablation performance of the woven expansion section material in two states can be examined at a time, the examination sample block adopts a stepped plunger type structure in order to avoid gas fire penetration at a butt joint part, and a combined body of the stepped plunger type ablation sample block and the trepanning expansion section is formed. The structure is arranged in a spray pipe shell to form a spray pipe, and the spray pipe is connected with a real solid rocket engine, so that the aim of examining the ablation performance of various woven expansion section materials through one-time solid rocket engine test run under the same working condition can be fulfilled. According to the utility model, the plurality of stepped plunger type examination sample blocks are embedded into the expansion section of the spray pipe, so that the examination of the ablation performance of the expansion section material under the actual working condition of a solid rocket engine is realized, and the examination authenticity and the examination efficiency of the expansion section material are improved.

Description

Technical Field

[0001] This utility model relates to the field of nozzle performance testing technology, specifically to a structure for assessing the ablation of the expansion section of a solid rocket engine nozzle. Background Technology

[0002] Solid rocket motor nozzles mainly consist of a throat liner, expander section, nozzle shell, and ablative insulation layer. The expander section is a crucial component of the nozzle, a key part for converting chemical energy into kinetic energy, and operates in a high-temperature, high-pressure, high-speed combustion environment. The ablation of the expander section material is affected by factors such as combustion gas characteristics, gas flow velocity, combustion chamber pressure, and the material's intrinsic properties. Currently, oxyacetylene ablation is the primary method for assessing the ablation of braided expander section materials. However, it cannot accurately reflect the ablation situation of the expander section in a solid rocket motor, thus failing to effectively verify the ablation characteristics of the expander section under real-world operating conditions. Evaluating the ablation performance of the expander section material through ablation tests during solid rocket motor trials is of significant guiding importance and engineering application value for the thermal structure design of the expander section. While assessing the ablation characteristics of the expander section material using a real solid rocket motor can reflect actual operating conditions, it involves long preparation cycles and high testing costs.

[0003] Currently, the main method for evaluating the ablation performance of braided expansion section materials involves using the same batch of fibers and the same process to prepare flat plates, then cutting ablation samples from these plates, and finally using the oxyacetylene ablation method to assess their ablation performance. However, the ablation environment of the oxyacetylene ablation method cannot realistically simulate the influence of factors such as the two-phase flow caused by Al2O3 particles and the composition of the combustion gases on ablation in solid rocket motors. Therefore, it is not effective in verifying the ablation characteristics of the expansion section under real operating conditions of solid rocket motors. Therefore, using an ablation test engine to evaluate the ablation of the expansion section is beneficial because it has a high similarity to actual operating conditions and is conducive to evaluating the ablation characteristics of the expansion section. However, the performance of braided expansion section materials or expansion section preparation processes needs to be verified through multiple solid rocket motor nozzle tests, and solid rocket motors are expensive. In addition, the braided expansion section is first prepared by using fibers and carbon cloth to make a preform, and then impregnated with resin and cured under pressure to finally produce the braided expansion section product. The above process results in the preparation cycle of the expansion section from fiber to preform to blank forming, which often takes more than a month or even half a year. The time and cost of testing the ablation performance of the expansion section are extremely high. Summary of the Invention

[0004] This invention addresses this problem by proposing an ablation assessment structure for the combined expansion section of a solid rocket motor nozzle. This structure solves the problems of high cost, long preparation time, and low assessment efficiency of existing methods, especially for the braided expansion section, which suffers from long preparation time and high cost, severely restricting the assessment of its ablation performance.

[0005] To address the aforementioned technical problems, one objective of this utility model is to provide an ablation testing structure for the expansion section of a solid rocket motor nozzle. The ablation testing sample adopts a stepped plunger structure, and the bonding surface between the ablation testing sample and the opening expansion section is a stepped cylindrical surface, forming a tortuous mating surface. It is further protected by the nozzle shell to prevent fire penetration. The ablation testing sample is a flat plate of the expansion section prepared from the same batch of fiber material and using the same process method in the expansion section of the nozzle to be tested.

[0006] Furthermore, the test sample was assembled with the nozzle expansion section in a small-diameter cylindrical shape facing upwards to prevent it from being swept away by the high-speed airflow during solid rocket engine operation.

[0007] Furthermore, the ablation test specimens were cut from woven flat plates prepared using the same batch of fibers and the same process, and bonded to low-cost carbon fiber phenolic resin molded products to achieve ablation performance testing of the ablation test specimens under real solid rocket motor conditions.

[0008] Furthermore, the test sample blocks are made of five or eight blocks.

[0009] Furthermore, based on the size of the expansion section, select two or more axial positions to assemble test specimens with circumferential openings.

[0010] Furthermore, the ablation test sample is cylindrical or conical.

[0011] Based on the same inventive concept, this utility model also provides a method for evaluating the ablation test structure of the expansion section of a solid rocket motor, the specific steps of which are as follows:

[0012] S1: Using the same batch of fibers and the same preparation process, two types of carbon fiber woven plates, T700 and T800, were prepared. Then, six stepped plunger ablation samples were cut from each of the woven plates.

[0013] S2: Low-cost carbon fiber phenolic resin molded products are used as the nozzle expansion section material. Holes corresponding to the stepped plunger test sample are machined at two axial positions in a circumferentially distributed manner in the expansion section. Six holes are opened at each axial position and staggered by 30°.

[0014] S3: The stepped plunger test sample block and the opening expansion section are bonded and assembled with HX98-1 adhesive. The assembly method is that the small diameter cylindrical end of the stepped plunger test sample block faces the inner surface of the expansion section.

[0015] S4: After the adhesive between the stepped plunger sample and the expansion section has cured for 48 hours, the outer surface of the expansion section is processed.

[0016] S5: The expansion section with the ablation test sample block is bonded to the nozzle housing 5 with HX98-1 adhesive to form the nozzle body;

[0017] S6: The throat liner (composed of carbon / carbon throat liner 1 and ablation insulation layer 2 bonded together) is installed into the nozzle body to form a solid rocket engine nozzle that can be used for ground test.

[0018] Furthermore, the nozzle throat diameter is φ48.5mm, the expansion ratio is 13.8, the maximum working pressure of the solid rocket motor in the ground test is 6.5MPa, and the working time is not less than 12s.

[0019] Furthermore, the upper cylinder diameter of the stepped plunger-type test sample block in S1 is Φ10 and the lower cylinder diameter is Φ18, with a total thickness of 15mm.

[0020] Furthermore, after the ground test of the solid rocket engine expansion section ablation test structure, the remaining thickness of the ablation test sample is tested, and the ablation rate of the solid rocket engine ablation test sample under the working conditions is obtained by (thickness before test - remaining thickness after test) / working time.

[0021] The above-mentioned one or more technical solutions of this utility model have at least one or more of the following technical effects: The present utility model proposes to cut a stepped plunger-type ablation test sample from a flat material made of the same batch of fibers and the same process, and embed it into the expansion section of a low-cost carbon fiber phenolic resin molded product. This realizes the test of the ablation performance of the braided expansion section material under real working conditions. At the same time, it avoids the problem of being limited by the long preparation cycle and high cost of the braided expansion section material, improves the authenticity and efficiency of the test of the braided expansion section material, and saves the test cost.

[0022] By using a stepped plunger-type ablation test sample block and assembling it into a nozzle in a low-cost expansion section material, the ablation performance of different expansion section materials can be tested in a single test under real working conditions. This reduces the test cost of braided expansion section materials and improves the authenticity and efficiency of the test.

[0023] The structure adopts an ablation test sample block bonded and embedded into the nozzle expansion section. The mating surface between the ablation test sample block and the opening expansion section is a stepped cylindrical surface, and the nozzle shell is bonded to the outer wall. The stepped mating structure + the nozzle shell bonded to the outer wall can prevent the ablation test sample block from flying out when the solid rocket engine is working, and can also prevent fire from penetrating the gap at the mating surface of the expansion section.

[0024] It can realize the ablation performance test of the braided expansion section material under real working conditions. Compared with the expansion section using braided products, the manufacturing cost is low and the cycle is short. At the same time, it can test the ablation performance of at least two expansion section materials at one time. Attached Figure Description

[0025] Figure 1 : Stepped plunger type test sample block;

[0026] Figure 2 Schematic diagram of the opening expansion section;

[0027] Figure 3 The front and right views of the expanded section after processing;

[0028] Figure 4 Exploded view of the expanded section after processing;

[0029] Figure 5 Schematic diagram of the nozzle body;

[0030] Figure 6 Schematic diagram of nozzle structure;

[0031] Figure 7 : A combined expansion section structure with five test samples evenly distributed in a circumferential direction;

[0032] Among them: 1-throat liner, 2-ablation insulation layer, 3-low-cost opening expansion section, 4-ablation test sample, 5-nozzle shell. Detailed Implementation

[0033] This invention proposes a method for evaluating the ablation performance of expanded section materials under actual solid rocket engine operating conditions. The specific method is as follows: Select the same batch of fiber materials from the woven expanded section to be evaluated, and prepare expanded section plates using the same process. Depending on the object to be evaluated, different compression ratios and different fiber materials can be selected to prepare expanded section plates. Then, cut a stepped plunger-type ablation test sample from the plate and place it in a low-cost carbon fiber phenolic resin molded expanded section product in one go, thereby shortening the preparation cycle of the woven expanded section to be evaluated and reducing the evaluation cost.

[0034] To prevent fire at the docking points during testing, the ablation test specimens are designed as stepped plungers, placed at different axial positions in the nozzle expansion section. The stepped plunger test specimens at the same axial position can be made of the same or different materials. Six ablation performance test specimens can be assembled at each axial position. After the ablation performance test specimens are bonded and cured, the nozzle shell is then bonded to them to further limit the structure of the stepped plunger ablation performance test specimens and prevent them from flying out during testing. Finally, the nozzle is formed for testing.

[0035] This utility model relates to an ablation assessment structure for the braided expansion section of a solid rocket engine nozzle. By embedding multiple stepped plunger-type assessment blocks into the expansion section of the nozzle, the ablation performance of the expansion section material under actual operating conditions of a solid rocket engine is assessed, thereby improving the authenticity and efficiency of the expansion section material assessment.

[0036] The current method for evaluating the ablation performance of braided expansion section materials mainly involves using the same batch of fibers and the same process to prepare flat plates, then cutting ablation samples from the plates, and finally using the oxyacetylene ablation method to evaluate their ablation performance. However, the ablation environment of the oxyacetylene ablation method cannot realistically simulate the influence of factors such as the two-phase flow caused by Al2O3 particles and the composition of the combustion gas on ablation in solid rocket motors. Therefore, it is not possible to effectively verify the ablation characteristics of the expansion section under real operating conditions of solid rocket motors.

[0037] This invention proposes an ablation testing structure for a solid rocket motor nozzle combined expansion section. The expansion section consists of an ablation testing sample block and a low-cost perforated expansion section. It can test the ablation performance of two types of braided expansion section materials at the same time. To avoid gas burn-through at the docking point, the testing sample block adopts a stepped plunger structure, forming a combination of a stepped plunger ablation sample block and a perforated expansion section. This structure is installed in the nozzle shell to form the nozzle, which is then connected to a real solid rocket motor. This allows for the testing of the ablation performance of multiple braided expansion section materials under the same operating conditions through a single solid rocket motor test.

[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of the present utility model, and not all of the embodiments obtained. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model are within the protection scope of the present utility model.

[0039] This utility model proposes a solid rocket engine nozzle structure for evaluating the braided expansion section material;

[0040] Two types of carbon fiber, T700 and T800, were woven flat plates made using the same batch of fibers and the same preparation process. Then, six stepped plunger ablation samples were cut from each of the woven flat plates.

[0041] The stepped plunger-type test sample block has an upper cylindrical diameter of Φ10 and a lower cylindrical diameter of Φ18.

[0042] Low-cost carbon fiber phenolic resin molded products were used as the nozzle expansion section material. Holes corresponding to the stepped plunger-type test sample were machined at two axial positions in a circumferentially distributed manner within the expansion section. Six holes were drilled at each axial position, staggered by 30°. The axial positions of the holes were taken at 41 and 42 points from the small end of the diffuser section, corresponding to pressures of 0.32 MPa and 0.13 MPa, respectively. The structural form is as follows: Figure 1-2 As shown;

[0043] The stepped plunger-type test sample block and the opening expansion section were bonded and assembled using HX98-1 adhesive. The assembly method was that the small-diameter cylindrical end of the stepped plunger-type test sample block faced the inner surface of the expansion section. Figure 3 These are the front and right views of the expanded section after processing, where 41 is a stepped plunger sample cut from a T800 carbon fiber woven flat product, and 42 is a stepped plunger sample cut from a T700 carbon fiber woven flat product.

[0044] After the adhesive between the stepped plunger-type specimen and the expansion section cured for 48 hours, the outer surface of the expansion section was machined. The exploded view of the completed expansion section is shown below. Figure 4 As shown;

[0045] The expansion section with the ablation test sample is bonded to the nozzle housing 5 using HX98-1 adhesive to form the nozzle body, as shown below. Figure 4 As shown;

[0046] The throat liner body, composed of a throat liner 1 and an ablation insulation layer 2 bonded together, is installed into the nozzle body to form a solid rocket motor nozzle suitable for ground test evaluation. The nozzle structure is shown below. Figure 5 ;

[0047] The nozzle throat liner is a three-dimensional woven carbon / carbon composite material, the ablation insulation layer is a high-silica fiber phenolic resin molded product, the nozzle shell is 30CrMnSi alloy steel, the opening expansion section is a carbon fiber phenolic resin molded product, and the ablation test samples are stepped plunger-type samples cut from T700 and T800 carbon fiber woven flat products.

[0048] HX98-1 adhesive has a shear strength ≥18.0MPa, a non-uniformity and tear strength ≥22.0kN / m, and a curing time ≥48h; nozzle throat diameter φ48.5mm, maximum engine working pressure 6.5MPa, and effective working time 12s.

[0049] The combined expansion section structure with five test samples evenly distributed in a circumferential direction Figure 7 As shown, the combined structure uses five, eight or other numbers of test samples. Alternatively, two or more axial positions can be selected to assemble the test samples with circumferential openings according to the size of the expansion section. The ablation test samples can be cylindrical or conical as needed.

[0050] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this utility model without departing from the spirit and scope of the embodiments of this utility model. Therefore, if these modifications and variations to the embodiments of this utility model fall within the scope of the claims of this utility model and their equivalents, then this utility model also intends to include these modifications and variations.

Claims

1. A structure for assessing the ablation of the expansion section of a solid rocket motor nozzle, characterized in that: The ablation test sample adopts a stepped plunger structure. The bonding surface between the ablation test sample and the opening expansion section is a stepped cylindrical surface, forming a tortuous mating surface. It is further protected by the nozzle shell to prevent fire penetration. The ablation test sample is an expansion section plate made of the same batch of fiber material and the same process method as the expansion section of the nozzle to be tested.

2. The ablation assessment structure for the expansion section of a solid rocket motor nozzle according to claim 1, characterized in that: The test sample was assembled with the nozzle expansion section with the small-diameter cylinder facing upwards.

3. The ablation assessment structure for the expansion section of a solid rocket motor nozzle according to claim 1, characterized in that: The test sample blocks consist of five or eight blocks.

4. The ablation assessment structure for the expansion section of a solid rocket motor nozzle according to claim 1, characterized in that: Based on the size of the expansion section, select two or more axial positions to assemble test specimens with circumferential openings.

5. The ablation assessment structure for the expansion section of a solid rocket motor nozzle according to claim 1, characterized in that: The ablation test specimens are cylindrical or conical.

6. The ablation assessment structure for the expansion section of a solid rocket motor nozzle according to claim 1, characterized in that: The stepped plunger-type test sample block has an upper cylindrical diameter of Φ10, a lower cylindrical diameter of Φ18, and a total thickness of 15mm.

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