Method for using solid engine jet pipe after long-time storage

Abstract

According to the method for using the solid engine jet pipe stored for a long time, size detection, airtight test detection, bonding performance detection, water pressure detection and material performance detection are conducted on the jet pipe, a judgment basis is obtained, and whether the jet pipe stored for a long time can be recycled or not is determined. On the premise that the solid rocket engine jet pipe is not subjected to ignition test, whether the solid rocket engine jet pipe is normally used or not can be judged according to results of jet pipe size detection, ultrasonic nondestructive detection and material performance detection. And the scrap cost and the cost for judging whether the use is normal or not are reduced.

Description

Technical Field

[0001] The present invention relates to the field of engine detection, in particular to a method for using a solid rocket engine nozzle after long-term storage and transportation. The present invention effectively solves the problem of whether the nozzle can be used after long-term storage, and relates to non-destructive detection (ultrasonic detection) and material performance detection of solid rocket engine nozzles. Background Art

[0002] Solid rocket engine nozzles are subjected to harsh working conditions such as high temperature, high pressure, flame, and airflow impact during operation, so they need to be inspected regularly to confirm the usability of the nozzles. CT, or computer tomography, is usually used for factory inspection of nozzle raw materials to effectively detect volume defects inside non-metallic materials. However, after the nozzle is assembled, it is inconvenient to use CT to inspect it. In order to detect damage during storage and transportation, appropriate detection methods must be used for in-service inspection. Ultrasonic testing methods can be used to implement non-destructive testing of product interface defects.

[0003] In the existing technology, solid rocket engine nozzles are scrapped after 10 years of storage, resulting in large losses. Therefore, a method for detecting and recycling nozzles stored for an ultra-long term is proposed to reduce the loss of nozzles. Summary of the invention

[0004] In order to overcome the shortcomings of the prior art, the present invention provides a method for using a solid rocket engine nozzle after long-term storage. Existing long-term storage nozzles are all scrapped after being overdue, resulting in large losses. Based on this, a method for detecting and determining the results of nozzles stored for an ultra-long period of time is proposed. By performing size detection, airtightness test detection, bonding performance detection (ultrasonic detection), water pressure detection and material performance detection on the nozzle, a judgment basis is obtained to determine whether the nozzle can be recycled after long-term storage.

[0005] The technical solution adopted by the present invention to solve the technical problem includes the following steps:

[0006] The first step is to receive the solid rocket motor nozzle after long-term storage and conduct appearance inspection;

[0007] Visually inspect the outer surface of the nozzle shell to see if there are any excess objects, dents, deformations, scratches or rust. Visually inspect the connecting threaded holes to see if there are any burrs or foreign objects, defects, cracks or rust. Inspect the non-metallic surface of the nozzle to confirm that there are no scratches, bumps, debris or oil stains.

[0008] The second step is to conduct size inspection, airtightness test, DR or CT inspection and bonding performance inspection on the nozzle;

[0009] The third step is water pressure test;

[0010] The water pressure test is a random inspection item. 1-2 nozzles are selected from each batch after long-term storage for the test. If the nozzle is a segmented nozzle, the nozzle is disassembled into the front section and the rear section, and the front section shell including the convergent section is subjected to a water pressure test.

[0011] The hydraulic test fixture is designed according to the nozzle shell interface. The hydraulic test pressure refers to the nozzle shell detection pressure or the new engine working pressure. If the test is qualified, it means that the batch of nozzles has passed the hydraulic test. The test nozzles are scrapped and will not be recycled.

[0012] The water pressure test pressure is less than the bursting pressure Pb calculated based on the minimum design thickness of the nozzle shell throat;

[0013] Step 4: Metal material performance testing and non-metal material performance testing;

[0014] Material performance testing is a random inspection item, and one nozzle is selected from each batch after long-term storage for testing;

[0015] Test the properties of non-metallic materials to determine whether they meet the material standards.

[0016] Step 5: Result determination

[0017] After completing the first to fourth steps of testing, the nozzle status after long-term storage of the batch is judged. The key indicators for judgment are:

[0018] (1) Material performance testing;

[0019] (2) Dimension inspection;

[0020] (3) Nondestructive testing;

[0021] (4) Water pressure testing;

[0022] If there are unqualified items in the key indicators, the product will be scrapped directly if the situation is serious, and will be determined whether it can be used based on analysis or simulation calculation of the specific situation if the situation is minor;

[0023] If the key indicators are qualified and there are problems with other test items, they can be repaired and used;

[0024] If all key indicators are qualified and the other test items are qualified, it can be used as is.

[0025] In the second step, the dimension inspection is as follows: measuring the key dimensions of the nozzle, including the throat diameter, the outlet inner diameter, the outlet outer diameter, the butt thread, the total length, the total weight and the positioning surface diameter;

[0026] In the second step, the airtightness test is as follows: install the nozzle on the airtightness test fixture, charge the nozzle with 0.15±0.02MPa under the environmental conditions of room temperature 20±10℃ and relative humidity not more than 80%, and maintain the pressure for 15 minutes. If the pressure drop is zero, the airtightness test is qualified;

[0027] In the second step, the DR or CT inspection is as follows: perform DR scanning on the nozzle, process the formed digital image information, obtain the longitudinal section passing through the central axis of the nozzle, and another longitudinal section perpendicular to the longitudinal section, a total of 2 longitudinal section projection images, determine the internal material and bonding interface defects of the nozzle based on the DR results, and determine the axial size, circumferential position and size of the defects, perform CT section scanning on the suspected defective parts, determine the axial position, circumferential position and size of the defects, this item is a random inspection item.

[0028] In the second step, the bonding performance test is as follows: the outer surface of the nozzle is cleaned, the insulation layer and the shell bonding at the nozzle inlet and outlet are observed, and the nozzle shell and the nozzle insulation bonding surface are tested by ultrasonic testing. If large-scale debonding or penetrating debonding occurs, the nozzle cannot be used and is scrapped. If large-scale debonding or penetrating debonding does not occur, proceed to the next step of testing.

[0029] The explosion pressure P b for:

[0030]

[0031] In the formula, k β is the material strength coefficient, σ b is the strength limit of the material, h is the minimum design wall thickness of the nozzle shell throat; D c is the nozzle body throat diameter.

[0032] The metal material performance test is as follows: determine the axial position of the slice, require at least one position of the convergence section and the expansion section, cut 6 test pieces in the radial direction at each position, obtain the tensile strength of the test piece material by the stretching method, and the measured tensile strength is greater than the standard strength of the material, which is qualified;

[0033] The non-metallic material performance test is as follows: test pieces are cut at the insulation positions of the convergent section, throat lining, and expansion section, with no less than 6 pieces at each position. After the non-metallic material is taken out, the insulation layer material is subjected to X-ray inspection in accordance with GJB 1187A-2001 "Radiographic Inspection" to confirm whether there are other inclusions, cracks, or loose defects.

[0034] The material performance test of the throat liner includes:

[0035] (1) Density;

[0036] (2) Degree of graphitization;

[0037] (3) Plasma ablation rate;

[0038] (4) Specific heat capacity at 800°C;

[0039] (5) Thermal conductivity at 800°C: circumferential and axial;

[0040] (6) Average linear expansion coefficient at 800°C: circumferential and axial directions;

[0041] (7) Compression strength, tensile strength, bending strength, shear strength: circumferential and axial;

[0042] The material performance test of the convergence section and the expansion section includes:

[0043] (1) Density;

[0044] (2) Tensile strength;

[0045] (3) Compression strength;

[0046] (4) Specific heat capacity from room temperature to 250°C;

[0047] (5) Thermal conductivity from room temperature to 250°C;

[0048] (6) Average linear expansion coefficient from room temperature to 250°C;

[0049] (7) Oxyacetylene ablation rate.

[0050] The beneficial effect of the present invention is that it can judge whether the solid rocket engine nozzle is in normal use based on the results of nozzle size detection, ultrasonic non-destructive detection and material performance detection without ignition test (one-time use), thereby reducing the cost of scrapping and the cost of judging whether it is in normal use. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The following is a flow chart of the detection.

[0052] Figure 2 Schematic diagram of DR or CT detection cross section.

[0053] Figure 3 Schematic diagram of the nozzle shell test piece selection position, Figure 3 (a) is a schematic diagram of the axial position. Figure 3 (b) is a schematic diagram of the circumferential position.

[0054] Figure 4 Schematic diagram of the test piece size.

[0055] Where, L1 is the total length of the test piece; h is the thickness of the test piece; L0 is the original gauge length ( S 0- cross-sectional area of ​​effective position of test piece); r- radius of transition arc; Lc- parallel length (>L0+b0 / 2);

[0056] Figure 5 Schematic diagram of the location of the nozzle non-metallic material test piece selection, Figure 5 (a) is a schematic diagram of the axial position. Figure 5 (b) is a schematic diagram of the circumferential position.

[0057] Figure 6 Airtightness test inspection diagram.

[0058] Figure 7 Water pressure test inspection diagram.

[0059] Figure 8 For metal material performance testing, Figure 8 (a) Cut the axial position of the metal test piece, Figure 8 (b) Cut the shell after the test piece is taken, Figure 8 (c) Metal test piece after cutting.

[0060] Fig. 9 Non-metallic material performance testing, Fig. 9 (a) Cut the axial position of the non-metallic specimen, Fig. 9 (b) The insulation layer specimen after cutting, Fig. 9 (c) Graphite throat liner specimen after cutting. DETAILED DESCRIPTION

[0061] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0062] The shell is recycled after long-term storage. Figure 1 As shown:

[0063] The first step is to receive the solid rocket motor nozzle after long-term storage and conduct appearance inspection;

[0064] Visually inspect the outer surface of the nozzle shell to see if there are any excess objects, dents, deformations, scratches or rust. Visually inspect the connecting threaded holes to see if there are any burrs or foreign objects, defects, cracks or rust. Inspect the non-metallic surface of the nozzle to confirm that there are no scratches, bumps, debris or oil stains.

[0065] The second step is to conduct size inspection, airtightness test, DR or CT inspection and bonding performance inspection (ultrasonic inspection) on the nozzle.

[0066] The size inspection includes: measuring the key dimensions of the nozzle, including throat diameter, outlet inner diameter, outlet outer diameter, docking thread, total length, total weight and positioning surface diameter;

[0067] The airtightness test is as follows: install the nozzle on the airtightness test fixture, and charge to 0.15±0.02MPa under the environmental conditions of normal temperature (20±10)℃ and relative humidity not more than 80%, and maintain the pressure for 15 minutes. If the pressure drop is zero, the airtightness test is qualified;

[0068] DR or CT detection is as follows: perform DR scanning on the nozzle, process the formed digital image information, obtain the longitudinal section passing through the central axis of the nozzle, and another longitudinal section perpendicular to the longitudinal section, such as Figure 2 As shown, there are 2 longitudinal section projection images in total. According to the DR results, the defects of the internal material and bonding interface of the nozzle are determined, and the axial size, circumferential position and size of the defects are determined. A CT section scan is performed on the suspected defective parts to determine the axial position, circumferential position and size of the defects. This item is a random inspection item.

[0069] The bonding performance test is as follows: clean the outer surface of the nozzle, observe the bonding conditions of the insulation layer and shell at the nozzle inlet and outlet, and use ultrasonic testing to test the nozzle shell and nozzle insulation bonding surface. If large-area debonding or penetrating debonding occurs, the nozzle cannot be used and is scrapped. If no large-area debonding or penetrating debonding occurs, proceed to the next step of testing.

[0070] Step 3: Water pressure test

[0071] The water pressure test is a random inspection item. 1-2 nozzles are selected from each batch after long-term storage for the test. If the nozzle is a segmented nozzle, the nozzle is disassembled into the front section and the rear section, and the front section shell including the convergent section is subjected to a water pressure test.

[0072] The hydraulic test fixture is designed according to the nozzle shell interface. The hydraulic test pressure refers to the nozzle shell detection pressure or the new engine working pressure. If the test is qualified, it means that the batch of nozzles has passed the hydraulic test. The test nozzles are scrapped and will not be recycled.

[0073] The water pressure test pressure is less than the bursting pressure P calculated based on the minimum design thickness of the nozzle shell throat. b for:

[0074]

[0075] In the formula, k β is the material strength coefficient, σ b is the strength limit of the material, h is the minimum design wall thickness of the nozzle shell throat; D c is the nozzle shell throat diameter;

[0076] Where, is the material strength coefficient, is the strength limit of the material, is the minimum design wall thickness of the nozzle shell throat; is the nozzle shell throat diameter;

[0077] Step 4: Metal material performance testing and non-metal material performance testing;

[0078] Material performance testing is a random inspection item, and one nozzle is selected from each batch after long-term storage for testing;

[0079] Metal material performance testing is as follows: Figure 3 Determine the axial position of the slice as shown, requiring at least one position in the convergence section and the expansion section, according to Figure 3 Cut 6 test pieces along the radial direction at each location as shown, and the test piece size is as follows Figure 4 As shown, the tensile strength of the test piece material is obtained by the stretching method, and the material is qualified if the measured tensile strength is greater than the standard strength of the material.

[0080] Non-metallic material performance testing: In the convergence section ( Figure 5 a position 1), throat lining ( Figure 5 a, position 2), expansion segment ( Figure 5 Position a3) Cut test pieces at the insulation position, with no less than 6 pieces at each position. After taking out the non-metallic materials, perform X-ray inspection on the insulation layer material in accordance with GJB1187A-2001 "Radiographic Inspection" to confirm whether there are other inclusions, cracks or loose defects.

[0081] Test the properties of non-metallic materials to determine whether they meet the material standards.

[0082] Throat lining material performance testing includes:

[0083] (1) Density

[0084] (2) Graphitization degree

[0085] (3) Plasma ablation rate

[0086] (4) Specific heat capacity (800℃)

[0087] (5) Thermal conductivity (800°C): Circumferential and axial

[0088] (6) Average linear expansion coefficient (800°C): circumferential and axial

[0089] (7) Compression strength, tensile strength, bending strength, shear strength: circumferential and axial

[0090] The material performance testing of the convergence section and expansion section includes:

[0091] (1) Density

[0092] (2) Tensile strength

[0093] (3) Compression strength

[0094] (4) Specific heat capacity (normal temperature ~ 250°C)

[0095] (5) Thermal conductivity (normal temperature ~ 250°C)

[0096] (6) Average linear expansion coefficient (normal temperature ~ 250°C)

[0097] (7) Oxyacetylene ablation rate

[0098] Step 5: Result determination

[0099] After completing the first to fourth steps of testing, the nozzle status after long-term storage of the batch is judged. The key indicators for judgment are:

[0100] (1) Material performance testing;

[0101] (2) Dimension inspection;

[0102] (3) Nondestructive testing;

[0103] (4) Water pressure testing;

[0104] If there are unqualified items in the key indicators, the serious ones will be directly scrapped, while the minor ones will need to be analyzed or simulated according to the specific situation to determine whether they can be used;

[0105] If the key indicators are qualified and there are problems with other test items, they can be repaired and used;

[0106] If all key indicators are qualified and the other test items are qualified, it can be used as is.

[0107] In an embodiment of the present invention, a certain type of solid rocket engine nozzle is inspected after long-term storage. The nozzle is a segmented structure and has been stored for more than 10 years. The nozzle is subjected to size inspection, air tightness inspection, water pressure inspection, and material property inspection, and the results are as follows.

[0108] (1) Figure 6 As shown, the nozzle was tested for air tightness and found to be qualified;

[0109] (2) Figure 7 As shown, the front section shell of the nozzle was subjected to a water pressure test and the test was qualified;

[0110] (3) Figure 8 As shown, the nozzle shell material properties are tested and a test piece is cut from the shell;

[0111] (4) Fig. 9 As shown, the performance of the non-metallic materials of the nozzle was tested, and the insulation layer specimens and the graphite throat liner specimens were cut.

Claims

1. A method for using a solid rocket engine nozzle after long-term storage, characterized in that The steps include: The first step is to receive the solid rocket motor nozzle after long-term storage and conduct appearance inspection; Visually inspect the outer surface of the nozzle shell to see if there are any extraneous objects, bruises, deformations, scratches or rust; visually inspect the connecting threaded holes to see if there are any burrs or foreign objects, defects, cracks or rust; inspect the non-metallic surface of the nozzle to confirm that there are no scratches, bumps, slag or oil stains; The second step is to conduct size inspection, airtightness test, DR or CT inspection and bonding performance inspection on the nozzle; The third step is water pressure test; The water pressure test is a random inspection item. 1-2 nozzles are selected from each batch after long-term storage for the test. If the nozzle is a segmented nozzle, the nozzle is disassembled into the front section and the rear section, and the front section shell including the convergent section is subjected to a water pressure test. The hydraulic test fixture is designed according to the nozzle shell interface. The hydraulic test pressure refers to the nozzle shell detection pressure or the new engine working pressure. If the test is qualified, it means that the batch of nozzles has passed the hydraulic test. The test nozzles are scrapped and will not be recycled. The water pressure test pressure is less than the bursting pressure P calculated based on the minimum design thickness of the nozzle shell throat. b ; Step 4: Metal material performance testing and non-metal material performance testing; Material performance testing is a random inspection item, and one nozzle is selected from each batch after long-term storage for testing; Test the performance of non-metallic materials to determine whether they meet material standards; Step 5: Result determination After completing the first to fourth steps of testing, the nozzle status after long-term storage of the batch is judged. The key indicators for judgment are: (1) Material performance testing; (2) Dimension inspection; (3) Nondestructive testing; (4) Water pressure testing; If there are unqualified items in the key indicators, the product will be scrapped directly if the situation is serious, and will be determined whether it can be used based on analysis or simulation calculation of the specific situation if the situation is minor; If the key indicators are qualified and there are problems with other test items, they can be repaired and used; If all key indicators are qualified and the other test items are qualified, it can be used as is.

2. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: In the second step, the dimension inspection is to measure the key dimensions of the nozzle, including the throat diameter, outlet inner diameter, outlet outer diameter, docking thread, total length, total weight and positioning surface diameter.

3. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: In the second step, the air-tightness test is as follows: install the nozzle on the air-tightness test fixture, and under the environmental conditions of room temperature 20±10℃ and relative humidity not more than 80%, charge with 0.15±0.02MPa, maintain the pressure for 15 minutes, and the pressure drop is zero, then the air-tightness test is qualified.

4. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: In the second step, the DR or CT inspection is as follows: perform DR scanning on the nozzle, process the formed digital image information, obtain the longitudinal section passing through the central axis of the nozzle, and another longitudinal section perpendicular to the longitudinal section, a total of 2 longitudinal section projection images, determine the internal material and bonding interface defects of the nozzle based on the DR results, and determine the axial size, circumferential position and size of the defects, perform CT section scanning on the suspected defective parts, determine the axial position, circumferential position and size of the defects, this item is a random inspection item.

5. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: In the second step, the bonding performance test is as follows: the outer surface of the nozzle is cleaned, the insulation layer and the shell bonding at the nozzle inlet and outlet are observed, and the nozzle shell and the nozzle insulation bonding surface are tested by ultrasonic testing. If large-scale debonding or penetrating debonding occurs, the nozzle cannot be used and is scrapped. If large-scale debonding or penetrating debonding does not occur, proceed to the next step of testing.

6. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: The blasting pressure P b for: In the formula, k β is the material strength coefficient, σ b is the strength limit of the material, h is the minimum design wall thickness of the nozzle shell throat; D c is the nozzle body throat diameter.

7. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: The metal material performance test is as follows: determine the axial position of the slice, require at least one position in the convergence section and the expansion section, cut 6 test pieces radially at each position, obtain the tensile strength of the test piece material by the stretching method, and the measured tensile strength is greater than the standard strength of the material for passing the test.

8. The method for using a solid rocket engine nozzle after long-term storage according to claim 1, characterized in that: The non-metallic material performance test is as follows: test pieces are cut at the insulation positions of the convergent section, throat lining, and expansion section, with no less than 6 pieces at each position. After the non-metallic material is taken out, the insulation layer material is subjected to X-ray inspection in accordance with GJB 1187A-2001 "Radiographic Inspection" to confirm whether there are other inclusions, cracks, or loose defects.

9. The method for using a solid rocket engine nozzle after long-term storage according to claim 8, characterized in that: The material performance test of the throat liner includes: (1) Density; (2) Degree of graphitization; (3) Plasma ablation rate; (4) Specific heat capacity at 800°C; (5) Thermal conductivity at 800°C: circumferential and axial; (6) Average linear expansion coefficient at 800°C: circumferential and axial directions; (7) Compression strength, tensile strength, bending strength, shear strength: circumferential and axial.

10. The method for using a solid rocket engine nozzle after long-term storage according to claim 7, characterized in that: The material performance test of the convergence section and the expansion section includes: (1) Density; (2) Tensile strength; (3) Compression strength; (4) Specific heat capacity from room temperature to 250°C; (5) Thermal conductivity from room temperature to 250°C; (6) Average linear expansion coefficient from room temperature to 250°C; (7) Oxyacetylene ablation rate.

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