A double envelope prediction method for burning rate of high burning rate propellants

Abstract

The present invention provides a double-envelope estimation method for the burning rate of a high-burning-rate propellant, comprising the following steps: using a jet mill to grind sodium perchlorate raw material to obtain sodium perchlorate material that meets the particle size requirements; obtaining the discharge amount of the sodium perchlorate material within a fixed time interval; and calculating the average discharge amount within a unit time interval; sampling the sodium perchlorate material in each time interval, mixing the sampled samples evenly and then sampling them again, and then performing a particle size test to obtain the average particle size of the sodium perchlorate material; estimating the burning rate of the propellant according to the average discharge amount and average particle size of the sodium perchlorate material, respectively, to obtain an estimated range of the burning rate of the propellant, and the propellant contains sodium perchlorate with a specific content and the same particle size requirements. The method estimates the burning rate of the propellant at the same content by the average discharge amount of ammonium perchlorate and the particle size of ammonium perchlorate, thereby forming a double envelope of the estimation results, and improving the accuracy of the estimation of the burning rate of the propellant.

Description

Technical Field

[0001] The invention belongs to the technical field of solid propellants, and in particular relates to a double-envelope prediction method for the burning rate of a high-burning-rate propellant. Background Art

[0002] Solid propellant is an energetic composite material based on polymers and with specific properties. It is the energy source of solid rocket engines. It releases energy through chemical reactions in the engine, and uses the reaction products as working fluid to generate thrust for the engine. Currently, various types of tactical missiles have increasingly higher requirements for engine performance, which inevitably requires propellants with higher burning rates and better performance.

[0003] Fine ammonium perchlorate is one of the main components of solid propellants, and changes in its particle size and content are important means of regulating the burning rate of the propellant. In high-burning-rate propellants, due to the high content of fine ammonium perchlorate, a small change in its particle size will have a significant effect on the burning rate of the propellant. Therefore, the consistency of the properties between batches of fine ammonium perchlorate is a key factor in controlling the stability of the propellant's burning rate. Technical research on fine ammonium perchlorate pulverization technology and material property characterization is carried out to provide reliable indicators and methods for the prediction of propellant burning rate, thereby improving the stability of the burning rate during the charge production process.

[0004] With the rapid development of modern science and technology, traditional pulverizing processes and equipment can no longer meet the increasingly high requirements for pulverizing particle size and precision. Airflow pulverization is currently recognized as a mechanical pulverization method that can effectively obtain the smallest particle size, and is an indispensable and important means for the modern powder processing industry. At present, airflow pulverization is also widely used in the domestic ammonium perchlorate pulverization. Taking the QLD series fluidized bed airflow pulverizer as an example, the system consists of three parts: automatic feeding system, airflow pulverizer and automatic discharging system. It integrates multi-nozzle technology, fluidized bed technology, and horizontal classification technology. It is an important development direction of airflow mills. However, this type of equipment will still be affected by factors such as feeding consistency, channel blockage, and changes in ambient temperature and humidity in actual applications, resulting in significant changes in particle size and distribution, which may eventually lead to significant fluctuations in the burning rate of the propellant. For large batches of materials, the sampling and preservation of samples will also affect the representativeness and reference value of the test data.

[0005] At present, the material particle size control technology of domestic air flow milling equipment is still restricted by many influencing factors. It is necessary to establish the relationship between key influencing factors and propellant burning rate through fine control of the crushing process and the testing process, and improve the accuracy of the particle size test data in describing the properties of the entire batch of materials, so as to effectively estimate the propellant burning rate under specific material conditions and improve the consistency of the combustion performance of engine charge products. Summary of the invention

[0006] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, to provide a double-envelope prediction method for the burning rate of a high-burning-rate propellant, to improve the accuracy of the description of the properties of fine sodium perchlorate materials, to achieve effective prediction of the burning rate of the propellant under a specific material state, and to improve the consistency of the combustion performance of solid motor charge products.

[0007] The technical solution of the present invention is: a double envelope prediction method for the burning rate of a high burning rate propellant, comprising the following steps:

[0008] 1) using a jet mill to grind the same batch of sodium perchlorate raw materials to obtain sodium perchlorate materials with a specific particle size range;

[0009] 2) obtaining the discharge amount of the sodium perchlorate material in a fixed time interval from the start of processing to the end of processing of the batch of sodium perchlorate raw materials; on this basis, calculating the average discharge amount of the sodium perchlorate material in the fixed time interval;

[0010] 3) obtaining the average particle size of the sodium perchlorate material;

[0011] 4) estimating the burning rate of the propellant according to an average discharge amount of the sodium perchlorate material within a fixed time interval to obtain a first estimated burning rate value, and estimating the burning rate of the propellant according to an average particle size of the sodium perchlorate material to obtain a second estimated burning rate value; the propellant comprises a specific content of sodium perchlorate having a particle size range that is the same as that of the current sodium perchlorate material;

[0012] 5) Obtain an estimated range of the propellant burning rate based on the first burning rate estimated value and the second burning rate estimated value.

[0013] Preferably, the propellant burning rate is estimated according to the average discharge amount of the sodium perchlorate material within a fixed time interval to obtain a first estimated burning rate value, specifically:

[0014] Substituting the average discharge amount of the sodium perchlorate material within a fixed time interval into the corresponding relationship between the propellant burning rate and the average discharge amount of the sodium perchlorate material within the fixed time interval to solve, a first burning rate estimate is obtained, wherein the corresponding relationship is obtained by fitting historical data.

[0015] Preferably, the propellant burning rate is estimated according to the average particle size of the sodium perchlorate material to obtain a second estimated burning rate value, specifically:

[0016] The average particle size of the sodium perchlorate material is substituted into the corresponding relationship between the propellant burning rate and the average particle size of the sodium perchlorate material to obtain a second burning rate estimation value, wherein the corresponding relationship is obtained by fitting historical data.

[0017] Preferably, in step 3), the average particle size of the sodium perchlorate material is obtained, specifically:

[0018] The sodium perchlorate material is sampled at each time interval, and after the sampled samples are evenly mixed, a number of parallel samples are taken out from the mixed samples, and the particle size of the parallel samples is tested to obtain the particle size of the sodium perchlorate material of each parallel sample; and the average particle size of the sodium perchlorate material of each parallel sample is calculated.

[0019] Preferably, the number of parallel samples taken from the mixed sample ranges from 3 to 6.

[0020] Preferably, in the step 2), the average discharge amount of the sodium perchlorate material within a fixed time interval is calculated, specifically: after removing the discharge amount data of the first time interval and the last time interval in chronological order, the discharge amount in the remaining time intervals is averaged.

[0021] Preferably, the specific particle size range is 6 μm to 8 μm.

[0022] Preferably, the specific particle size range is 8 μm to 11 μm.

[0023] Preferably, the specific particle size range is 11 μm to 14 μm.

[0024] Preferably, the fixed time interval is 10 minutes to 12 minutes.

[0025] The advantages of the present invention compared with the prior art are:

[0026] (1) The present invention adds a characteristic parameter of the average discharge amount per unit time on the basis of the particle size and distribution of fine ammonium perchlorate (6-8 μm, 8-11 μm, 11-14 μm, or similar specifications), characterizes the microscopic properties of the material by the particle size and distribution of ammonium perchlorate, and characterizes the macroscopic properties of the material by the average discharge amount per unit time; thus, the accuracy of the properties of the ammonium perchlorate material is improved;

[0027] (2) The present invention covers each pulverizing unit for sampling of the whole batch of materials, and places the samples in a sealed tube after secondary mixing and sampling; the representativeness of the samples is improved by sampling and mixing in each pulverizing unit; the samples are stored in sealed tubes and discarded immediately after testing, thereby reducing the influence of environmental humidity on the particle size of the pulverized materials;

[0028] (3) The present invention obtains a fitting relationship between the average discharge amount of fine ammonium perchlorate and the burning rate of the propellant, obtains a fitting relationship between the particle size of fine ammonium perchlorate and the burning rate of the propellant, and estimates the burning rate of the propellant by the double envelope method. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic flow chart of a double-envelope prediction method for the burning rate of a high burning rate propellant according to the present invention;

[0030] Figure 2 This is a schematic diagram of the fitting relationship between the burning rate and the average discharge amount in Example 1 of the present invention;

[0031] Figure 3 This is a schematic diagram of the burning rate-average particle size fitting relationship of Example 1 of the present invention;

[0032] Figure 4 This is a schematic diagram of the fitting relationship between the burning rate and the average discharge amount in Example 3 of the present invention;

[0033] Figure 5 This is a schematic diagram of the burning rate-average particle size fitting relationship of Example 3 of the present invention. DETAILED DESCRIPTION

[0034] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0035] The present invention provides a double envelope prediction method for the burning rate of high burning rate propellants, such as Figure 1 As shown, two important steps are added to the current fine ammonium perchlorate crushing process:

[0036] 1. Collect the materials from a crushing unit at fixed time intervals, weigh and record them; after a batch of materials is crushed, remove the discharge data at the head and tail due to insufficient feed concentration or time, average the remaining data and record it as the average discharge amount.

[0037] 2. After completing the crushing of a batch of fine ammonium perchlorate, the materials in each crushing time unit will be sampled separately, and each sample will be fully mixed. After sampling again, they will be packaged in sealable sample tubes, and the particle size and distribution of multiple samples will be tested. After completing the consistency comparison, the average value will be calculated.

[0038] By collating and analyzing historical data, the fitting relationship between the average output of fine ammonium perchlorate and the burning rate of the propellant is obtained, and the fitting relationship between the particle size of fine ammonium perchlorate and the burning rate of the propellant is obtained. The burning rate value of the propellant is estimated by the double envelope formed by the two sets of fitting relationships, so as to obtain the recommended value of the fine ammonium perchlorate content at the target burning rate.

[0039] The following are the specific steps of the method of the present invention:

[0040] Step 1: Turn on the airflow mill and set the classifying wheel speed to 16-18 Hz;

[0041] Step 2: Set the crushing pressure of the airflow crusher to 0.7 MPa;

[0042] Step 3: Set the feed flow rate of the feeding device to 15-25 kg;

[0043] Step 4: Add 20-25 kg of base material to the airflow mill to ensure the concentration of ammonium perchlorate in the milling chamber when the airflow mill is started;

[0044] Step 5: Start the airflow mill, and the ammonium perchlorate material is forcibly fed into the lower part of the pulverizing chamber through the airflow jet form and enters the pulverizing area. The supersonic jet generated by the intense expansion and acceleration of the compressed air through the pulverizing nozzle forms a centripetal reverse jet flow field at the lower part of the pulverizing chamber. Under the action of the pressure difference, the material at the bottom of the mill is fluidized, and the accelerated material converges at the intersection of multiple nozzles, generating violent impact, collision and friction to be pulverized;

[0045] Step 6: After the air flow pulverization is completed, the fine ammonium perchlorate that meets the 6-8μm requirement is transported to the cyclone separator through the grading plate flow channel and the exhaust pipe as a product collection. The obtained fine ammonium perchlorate material is weighed at intervals of 10-12 minutes and recorded as the discharge amount per unit time. After a batch of materials is pulverized, the discharge amount data generated at the head and tail due to insufficient feed concentration or time are removed, and the remaining data is averaged and recorded as the average discharge amount;

[0046] Step 7: Use a powder sampler to sample fine ammonium perchlorate at different time units during the pulverization process, and mix all the samples. Finally, 3 to 4 parallel samples are obtained from the mixed material and placed in a sealed sample tube. After the particle size and distribution are tested, consistency comparison and average value calculation are performed;

[0047] Step 8: Use the average output, particle size and distribution of fine ammonium perchlorate to estimate the burning rate at the same content, thereby forming a double envelope of the estimated results. Adjust the content of fine ammonium perchlorate in the propellant formula with reference to the estimated results of the envelope.

[0048] Example 1

[0049] The specific process of this embodiment is:

[0050] Step 101: Turn on the airflow mill and set the classifying wheel speed to 18 Hz;

[0051] Step 102: setting the pulverizing pressure of the air flow pulverizer to 0.7 MPa;

[0052] Step 103: setting the feed flow rate of the feed device to 25 kg;

[0053] Step 104: Add 25 kg into the airflow mill to ensure the concentration of ammonium perchlorate in the milling chamber when the airflow mill is started;

[0054] Step 105: Start the airflow pulverizer;

[0055] Step 106: weigh the obtained batch of fine ammonium perchlorate material at intervals of 12 minutes, and record it as the discharge amount per unit time interval, see Table 1.

[0056] Table 1 Single barrel discharge volume under unit time interval of Example 1

[0057] Barrel 1 2 3 4 5 6 7 Output / kg 13 18.2 18.4 18.7 18.2 18.6 19 Barrel 8 9 10 11 12 13 14 Output / kg 19.1 19 19.8 20.3 20.4 21.1 21.1 Barrel 14 15 — — — — — Output / kg 21.2 13.9 — — — — —

[0058] Remove the discharge of 13 kg from the first barrel and 13.9 kg from the 15th barrel (the last barrel) in Table 1. The average discharge in Table 1 is calculated to be 19.5 kg.

[0059] Step 107: Use a powder sampler to sample the fine ammonium perchlorate at different time units during the pulverization process, and mix all the samples. Finally, three parallel samples are obtained from the mixed material and placed in sealed sample tubes for particle size and distribution testing. The particle size results are shown in Table 2.

[0060] Table 2 Example 1 Ammonium perchlorate particle size and distribution

[0061] Parallel number Particle size (D50) 1 5.97 2 5.75 3 5.98 average value 5.90 Standard Deviation 0.13

[0062] Step 108: Establish the corresponding relationship between the average discharge amount (16-20 kg) and the burning rate under similar conditions, see Figure 2 , the relationship between the two is as follows:

[0063] Y 1 = -0.0783X 1 + 18.8 (1)

[0064] The average discharge amount calculated in step 106 is X 1 =19.5, substitute into the above formula, calculate the burning rate Y 1 =17.27.

[0065] In the range of 16-20 kg average discharge, the corresponding relationship between fine ammonium perchlorate particle size and combustion rate is established. Figure 3 , the relationship between the two is as follows:

[0066] Y 2 = -0.5695X 2 + 20.423 (2)

[0067] According to the average particle size X calculated in step 107 2 =5.90Substitute into the above formula and calculate the burning rate Y 2 =17.06.

[0068] Step 109: The burning rate range achieved under the current crushing state is estimated to be [17.06, 17.27], thereby forming a double envelope of the estimated results. The actual burning rate of the propellant is 17.23 mm / s.

[0069] Example 2

[0070] The specific process of this embodiment is:

[0071] Step 201: Turn on the airflow mill and set the classifying wheel speed to 18 Hz;

[0072] Step 202: setting the pulverizing pressure of the air flow pulverizer to 0.7 MPa;

[0073] Step 203: setting the feed flow rate of the feed device to 15 kg;

[0074] Step 204: Add 25 kg into the airflow mill to ensure the concentration of ammonium perchlorate in the milling chamber when the airflow mill is started;

[0075] Step 205: Start the airflow pulverizer;

[0076] Step 206: The obtained batch of fine ammonium perchlorate material is weighed at intervals of 12 minutes, and recorded as the discharge amount per unit time interval, as shown in Table 3. The discharge amount of the first barrel (16.7 kg) and the discharge amount of the 15th barrel (the last barrel) (15 kg) in Table 3 are removed, and the average discharge amount in Table 3 is calculated to be 16.25 kg.

[0077] Table 3 Single barrel discharge volume under unit time interval of Example 2

[0078] Barrel 1 2 3 4 5 6 7 Output / kg 16.7 17.8 18 18.2 15.8 15.4 15.6 Barrel 8 9 10 11 12 13 14 Output / kg 15.5 15.6 15.6 15.7 16.2 16.3 15.8 Barrel 14 15 — — — — — Output / kg 16 15 — — — — —

[0079] Step 207: Use a powder sampler to sample the fine ammonium perchlorate at different time units during the pulverization process, and mix all the samples. Finally, three parallel samples are obtained from the mixed material and placed in sealed sample tubes for particle size and distribution testing. The particle size results are shown in Table 4.

[0080] Table 4 Example 2 Ammonium perchlorate particle size and distribution

[0081] Parallel No. Particle size (D50) 1 4.49 2 4.36 3 4.43 average value 4.43 Standard Deviation 0.07

[0082] Step 208: According to Figure 2 The corresponding relationship between the average discharge amount and the burning rate is shown in equation (1). The average discharge amount calculated in step 206 is X 1 =16.25, substitute into formula (1) and calculate the burning rate Y 1 =17.53.

[0083] According to the average particle size X calculated in step 207 2 =4.43Substitute into formula (2) to calculate the burning rate Y 2 =17.90.

[0084] Step 9: The estimated burning rate range under the current crushing state is [17.53, 17.90], thus forming a double envelope of the estimated results. The measured burning rate of the propellant is 17.88 mm / s.

[0085] Example 3

[0086] The specific process of this embodiment is:

[0087] Step 301: Turn on the airflow mill and set the classifying wheel speed to 16 Hz;

[0088] Step 302: setting the pulverizing pressure of the air flow pulverizer to 0.7 MPa;

[0089] Step 303: setting the feed flow rate of the feed device to 25 kg;

[0090] Step 304: Add 25 kg into the airflow mill to ensure the concentration of ammonium perchlorate in the milling chamber when the airflow mill is started;

[0091] Step 305: Start the airflow pulverizer;

[0092] Step 306: weigh the obtained batch of fine ammonium perchlorate material at intervals of 12 minutes, and record it as the discharge amount per unit time interval, see Table 5.

[0093] Table 5 Single barrel discharge volume under unit time interval of Example 3

[0094]

[0095]

[0096] Remove the discharge of 11.8 kg from the first barrel and 13.7 kg from the 15th barrel (the last barrel) in Table 5. The average discharge in Table 1 is calculated to be 25.1 kg.

[0097] Step 307: Use a powder sampler to sample the fine ammonium perchlorate at different time units during the pulverization process, and mix all the samples. Finally, three parallel samples are obtained from the mixed material and placed in sealed sample tubes for particle size and distribution testing. The particle size results are shown in Table 6.

[0098] Table 6 Example 3 Ammonium perchlorate particle size and distribution

[0099] Parallel number Particle size (D50) 1 5.11 2 5.08 3 5.13 average value 5.11 Standard Deviation 0.03

[0100] Step 308: Establish the corresponding relationship between the average discharge amount (23.5-25.5 kg) and the burning rate under similar conditions, see Figure 4 , the relationship between the two is as follows:

[0101] Y 1 = -0.3154X 1 + 24.294 (3)

[0102] The average discharge amount calculated in step 306 is X 1 =25.1, substitute into (3) above, and calculate the burning rate Y 1 =16.38.

[0103] In the range of 23.5-25.5 kg average discharge, the corresponding relationship between fine ammonium perchlorate particle size and combustion rate is established. Figure 5 , the relationship between the two is as follows:

[0104] Y 2 = -0.9677X 2 + 21.698 (4)

[0105] According to the average particle size X calculated in step 307 2 =5.11Substitute into formula (4) and calculate the burning rate Y 2 =16.75.

[0106] Step 309: The burning rate range achieved in the current pulverization state is estimated to be [16.38, 16.75], thereby forming a double envelope of the estimated results. The actual burning rate of the propellant is 16.70 mm / s.

[0107] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A double envelope prediction method for the burning rate of a high burning rate propellant, characterized in that: The following steps are involved: 1) Using a jet mill to grind the same batch of sodium perchlorate raw materials to obtain sodium perchlorate materials with a specific particle size range; 2) Obtain the discharge amount of the sodium perchlorate material in a fixed time interval from the start to the end of processing of the batch of sodium perchlorate raw materials; on this basis, calculate the average discharge amount of the sodium perchlorate material in the fixed time interval; 3) Obtaining the average particle size of the sodium perchlorate material; 4) estimating the burning rate of the propellant according to the average discharge amount of the sodium perchlorate material within a fixed time interval to obtain a first estimated burning rate value, and estimating the burning rate of the propellant according to the average particle size of the sodium perchlorate material to obtain a second estimated burning rate value; the propellant contains a specific content of sodium perchlorate having the same particle size range as the current sodium perchlorate material; 5) obtaining an estimated range of the propellant burning rate according to the first burning rate estimated value and the second burning rate estimated value; The propellant burning rate is estimated according to the average discharge amount of the sodium perchlorate material within a fixed time interval to obtain a first estimated burning rate value, which is specifically: Substituting the average discharge amount of the sodium perchlorate material within a fixed time interval into the corresponding relationship between the propellant burning rate and the average discharge amount of the sodium perchlorate material within the fixed time interval to solve, a first burning rate estimate is obtained, wherein the corresponding relationship is obtained by fitting historical data.

2. A double envelope prediction method for the burning rate of a high burning rate propellant according to claim 1, characterized in that: The propellant burning rate is estimated according to the average particle size of the sodium perchlorate material to obtain a second estimated burning rate value, which is specifically: The average particle size of the sodium perchlorate material is substituted into the corresponding relationship between the propellant burning rate and the average particle size of the sodium perchlorate material to obtain a second burning rate estimation value, wherein the corresponding relationship is obtained by fitting historical data.

3. A double envelope prediction method for the burning rate of a high burning rate propellant according to claim 1, characterized in that: In the step 3), the average particle size of the sodium perchlorate material is obtained, specifically: The sodium perchlorate material is sampled at each time interval, and after the sampled samples are evenly mixed, a number of parallel samples are taken out from the mixed samples, and the particle size of the parallel samples is tested to obtain the particle size of the sodium perchlorate material of each parallel sample; and the average particle size of the sodium perchlorate material of each parallel sample is calculated.

4. A double envelope prediction method for the burning rate of a high burning rate propellant according to claim 3, characterized in that: The number of parallel samples taken from the mixed sample ranges from 3 to 6.

5. A double envelope prediction method for the burning rate of a high burning rate propellant according to claim 1, characterized in that: In the step 2), the average discharge amount of the sodium perchlorate material within a fixed time interval is calculated, specifically, in chronological order, after removing the discharge amount data of the first time interval and the last time interval, the average of the discharge amounts in the remaining time intervals is calculated.

6. A double envelope prediction method for the burning rate of a high burning rate propellant according to any one of claims 1 to 5, characterized in that: The specific particle size range is 6 μm to 8 μm.

7. A double envelope prediction method for the burning rate of a high burning rate propellant according to any one of claims 1 to 5, characterized in that: The specific particle size range is 8 μm to 11 μm.

8. A double envelope prediction method for the burning rate of a high burning rate propellant according to any one of claims 1 to 5, characterized in that: The specific particle size range is 11 μm to 14 μm.

9. A double envelope prediction method for the burning rate of a high burning rate propellant according to any one of claims 1 to 5, characterized in that: The fixed time interval is 10min to 12min.

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