Method for identifying carrying capacity of liquid rocket

Abstract

The invention discloses a liquid rocket carrying capacity identification method which comprises the following steps: designing and calculating a standard trajectory meeting corresponding professional standard specifications according to determined carrying capacity identification standard conditions; adding a guidance control rate of a rocket, and calculating a zero-interference identification trajectory under a zero-interference condition; recording the residual amount of the final-stage propellant under the zero interference condition; determining the probability level required by the identification, and calculating the minimum simulation test frequency n according to the probability level; according to the minimum number of simulation tests, n simulation calculation tests are carried out, a propellant surplus sample with the sample size being n is obtained, and the final-stage safety margin of the propellant is calculated in a simulation mode; removing part of minimum values in the propellant surplus samples, and selecting the sample with the minimum propellant surplus from the remaining propellant surplus samples to calculate the carrying capacity of the rocket; the liquid rocket carrying capacity identification method and the standard process are summarized and extracted, and a foundation is laid for follow-up rocket carrying capacity identification.

Description

Technical Field

[0001] The invention relates to a method for evaluating the carrying capacity of a liquid rocket, in particular to a method for evaluating the carrying capacity of a rocket whose propellant is liquid, and belongs to the field of liquid launch vehicle trajectory design. Background Art

[0002] The carrying capacity is one of the most important core indicators of a launch vehicle. The carrying capacity assessment is to assess whether the rocket's carrying capacity meets the mission indicator requirements by combining actual flight sample data with simulation calculation methods.

[0003] As the number of launch vehicle models in my country increases and the mission density increases, my country's requirements for the equipment, combat effectiveness and refined design of launch vehicles are increasing. The demand for scientific identification of rocket carrying capacity is increasing. Many types of rockets are facing the need for carrying capacity identification. It is necessary to conduct research on the evaluation methods of rocket post-launch carrying capacity and orbital accuracy based on flight test data to provide strong support for optimizing the overall performance of rockets. However, due to the limitations of small flight samples of launch vehicles, it is difficult to identify the capabilities of liquid rockets through conventional methods of sufficient testing, and there are no standard methods for the identification of liquid rocket carrying capacity at home and abroad. Therefore, it is urgent to summarize and refine the identification methods suitable for liquid rocket carrying capacity, and form a process method that can guide the actual work, so as to guide the identification of the capabilities of my country's subsequent space launch missions.

[0004] A search was conducted on the methods for evaluating the carrying capacity of liquid launch vehicles that have been publicly published. In the journal article "Evaluation Method for GTO Carrying Capacity of Bipropellant Liquid Rockets" (Missiles and Space Launch Technology), the final stage propellant carrying capacity conversion coefficient was derived in detail based on the Tsiolkovsky formula, and the effectiveness of the calculation method was demonstrated in combination with actual flight test data. However, this method is only applicable to the evaluation and calculation of the carrying capacity of a single flight test result, and cannot be used to evaluate the carrying capacity of a type of rocket in the sense of multiple samples. How to effectively use the flight data of small or multiple rocket samples to scientifically and reasonably evaluate and calculate their carrying capacity is a problem worthy of study at present. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the deficiencies of the prior art, to provide a method for evaluating the carrying capacity of a liquid rocket, to summarize and refine the method and standard process for evaluating the carrying capacity of a liquid rocket, and to lay the foundation for subsequent evaluation of the carrying capacity of a rocket.

[0006] The technical solution of the present invention is: in the first aspect, a method for evaluating the carrying capacity of a liquid rocket is provided, comprising:

[0007] Determine the standard conditions for carrying capacity assessment based on the model of the rocket being assessed, the target orbit, and the engine and structure weight parameters obtained from actual flight regression;

[0008] According to the identification standard conditions, design and calculate a standard trajectory that meets the corresponding professional standards and specifications;

[0009] According to the calculation results of the standard trajectory, the guidance control rate of the rocket is added to calculate a zero-interference identification trajectory under zero-interference conditions; the remaining amount of the final stage propellant under zero-interference conditions is recorded;

[0010] Determine the specified probability level required for this identification Calculate the minimum number of simulation trials n according to the specified probability level;

[0011] According to the minimum number of simulation tests, n simulation tests are performed to obtain a sample of propellant remaining quantity with a sample size of n, and the final stage safety margin of the propellant is simulated and calculated;

[0012] Eliminate some of the minimum values ​​in the propellant remaining amount samples, and select the sample with the minimum propellant remaining amount from the remaining propellant remaining amount samples to calculate the rocket carrying capacity;

[0013] The propellant includes a combustion agent and an oxidizer.

[0014] Preferably, the standard conditions include: rocket original data and deviation, target orbit parameters, geophysical parameters and standard atmosphere parameters.

[0015] Preferably, the remaining amount of the final stage propellant under zero interference conditions is specifically recorded as: the remaining amount of the final stage propellant under zero interference conditions M r0 , and the final oxidant residual amount M under zero interference conditions y0 .

[0016] Preferably, the minimum number of simulation tests n is calculated as follows:

[0017]

[0018] In the formula, γ is the confidence level; φ -1 is the inverse function of the normal distribution function; specify the probability level Determined by the overall appraisal unit; ζ is the requirement The relative accuracy achieved.

[0019] Preferably, according to the minimum number of simulation tests, the final safety margin M of the combustion agent is simulated and calculated. ra 、Oxidant final safety margin M ya The method is:

[0020]

[0021] Among them, M r0 is the remaining amount of propellant in the final stage under zero interference conditions, M y0 is the remaining amount of final stage oxidizer propellant under zero interference conditions; are the sample means of the remaining amount of the fuel and oxidant respectively; S r , S y are the standard deviations of the samples of residual fuel and oxidizer respectively.

[0022] Preferably, the mean value of the residual amount of the fuel and oxidant samples is Standard deviation S of the remaining samples of fuel and oxidant r , S y The calculation method is:

[0023]

[0024] Among them, M ri 、M yi are respectively the remaining amounts of final stage fuel and oxidant in the i-th test.

[0025] Preferably, when removing some minimum values ​​in the propellant remaining amount samples, the method for determining the number of samples k to be removed is:

[0026] For a given probability level, calculate:

[0027]

[0028] Preferably, the method for calculating the rocket carrying capacity by selecting the sample with the smallest remaining amount among the remaining propellant remaining amount samples is:

[0029] Select the smallest sample with the smallest remaining amount from the remaining nk propellant remaining amount samples;

[0030] The calculation formula of carrying capacity is:

[0031]

[0032] Where M rP0 is the remaining amount of the sample fuel, M yP0 is the residual amount of oxidant, M z is the mass of the payload used in the standard trajectory calculation; λ0 is the conversion factor between the remaining available propellant and the carrying capacity of the rocket; M re is the unusable amount of fuel in the tank, M ye M is the unusable amount of oxidant in the tank; ra is the final stage safety margin of the propellant and the fuel, M ya It is the safety margin of the final stage of oxidizer propellant.

[0033] In a second aspect, a terminal device is provided, including:

[0034] a memory for storing instructions executed by at least one processor;

[0035] The processor is used to execute the instructions stored in the memory to implement the liquid rocket carrying capacity identification method as described above.

[0036] In a third aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions. When the computer instructions are executed on a computer, the computer executes the liquid rocket launching capability identification method as described above.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] (1) The present invention takes into account the variable remaining amount of liquid rocket propellant and proposes a method suitable for liquid propellant rocket carrying capacity evaluation, which can effectively handle the problem of converting the final stage propellant into carrying capacity evaluation;

[0039] (2) The present invention, by introducing identification standard conditions and simulation means, can combine the actual flight results of the rocket and the computer simulation capabilities to the greatest extent, scientifically identify the carrying capacity of a type of carrier rocket in the sense of small samples, and effectively solve the difficulty of carrying capacity identification caused by insufficient actual flight test times;

[0040] (3) The present invention transforms the random characteristics of the residual quantity of multiple flights of a launch vehicle into a safety margin calculated by simulation means, which can be applied to the evaluation and calculation of the carrying capacity of multiple flight test results, thereby realizing the evaluation of the carrying capacity of a type of rocket in the sense of multiple samples. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 The present invention is a flow chart of the method for evaluating the carrying capacity of a liquid rocket. DETAILED DESCRIPTION

[0042] The present invention first clarifies the initial conditions for liquid rocket carrying capacity appraisal by determining the appraisal standard conditions, then completes the standard trajectory calculation and the zero-interference appraisal trajectory calculation respectively, determines the number of simulation calculations based on the probability level set by the user, and finally obtains the final stage safety margin through simulation calculation, thereby calculating the carrying capacity appraisal value.

[0043] The method of liquid rocket carrying capacity evaluation can be divided into six steps: determining the evaluation standard conditions, calculating the evaluation standard trajectory, calculating the zero-interference evaluation trajectory, determining the probability level and the number of simulations, simulating and calculating the final stage safety margin, and calculating the evaluation carrying capacity. The flowchart of the method is shown in Figure 1The specific implementation steps are given below.

[0044] first step:

[0045] Determine the standard conditions for identification. In this step, the standard conditions for the identification of the carrying capacity need to be determined based on the model of the rocket to be identified, the target orbit, the engine obtained from the actual flight regression, the weight of the structure and other parameters. The standard conditions include the following: the original data of the rocket and the deviation, the target orbit parameters, the geophysical parameters and the standard atmosphere parameters. After this step, proceed to the second step.

[0046] Step 2:

[0047] Calculate the standard trajectory for identification. In this step, a standard trajectory is designed and calculated according to the identification standard conditions. The trajectory design result should meet the corresponding professional standards and specifications. After this step, proceed to the third step.

[0048] Step 3:

[0049] Calculate the zero-interference identification trajectory. In this step, based on the standard trajectory calculation results, add the guidance control rate of the rocket and calculate a zero-interference identification trajectory under zero-interference conditions. Record the remaining amount of the final stage propellant under zero-interference conditions as M r0 , record the remaining amount of the final stage oxidizer propellant under zero interference conditions as M y0 . After this step, proceed to step 4.

[0050] Step 4:

[0051] Determine the probability level and number of simulations. In this step, first determine the probability level specified by the task required for this assessment. Generally, 0.997 (3σ) is taken. Then, the minimum number of simulation tests n is calculated according to the probability level, and the calculation formula is:

[0052]

[0053] In the formula, γ is the confidence level, which is generally taken as 0.8; φ -1 is the inverse function of the normal distribution function; ζ is the requirement The relative accuracy achieved is generally based on The number of significant digits is 0.001 to 0.005.

[0054] After this step, proceed to step 5.

[0055] Step 5:

[0056] Simulate and calculate the final stage safety margin. In this step, according to the minimum number of simulation tests obtained in the fourth step, a simulation test is performed. A sample of propellant remaining amount with a sample size of n is obtained, that is, the remaining amount of the final stage combustion agent and oxidant in the i-th test is M respectively.ri 、M yi .

[0057] Calculate the sample mean of the remaining amount of fuel and oxidant according to the following formula Standard Deviation r , S y :

[0058]

[0059] Safety margin M of final stage fuel and oxidant ra 、M ya The calculation formula is:

[0060]

[0061] After this step, proceed to step 6.

[0062] Step 6:

[0063] Calculate and identify the carrying capacity. In this step, firstly, the corresponding k value is obtained according to the given probability level as follows:

[0064]

[0065] The k value represents the number of samples that need to be eliminated; the k smallest values ​​are eliminated in turn from the n samples of residual fuel and oxidant respectively, and the smallest sample among the remaining (nk) samples of residual propellant corresponds to the carrying capacity of the launch vehicle of this type, and the residual fuel of this sample is recorded as M rP0 , the remaining amount of oxidant M yP0 , the calculation formula of carrying capacity is:

[0066]

[0067] Where M z is the mass of the payload used in the standard trajectory calculation; λ0 is the conversion factor between the remaining available propellant and the carrying capacity of the rocket; M re 、M ye They are the unusable amounts in the fuel and oxidizer tanks respectively.

[0068] After the calculation is completed, the overall process ends.

[0069] In a second aspect, the present invention provides a terminal device, comprising:

[0070] a memory for storing instructions executed by at least one processor;

[0071] The processor is used to execute the instructions stored in the memory to implement the liquid rocket carrying capacity identification method as described above.

[0072] In a third aspect, the present invention provides a computer-readable storage medium, which stores computer instructions. When the computer instructions are executed on a computer, the computer executes the liquid rocket launching capability identification method as described above.

[0073] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

Claims

1. A method for evaluating the carrying capacity of a liquid rocket, characterized in that include: Determine the standard conditions for carrying capacity assessment based on the model of the rocket being assessed, the target orbit, and the engine and structure weight parameters obtained from actual flight regression; According to the identification standard conditions, design and calculate a standard trajectory that meets the corresponding professional standards and specifications; According to the calculation results of the standard trajectory, the guidance control rate of the rocket is added to calculate a zero-interference identification trajectory under zero-interference conditions; Record the remaining amount of final stage propellant under zero interference conditions; Determine the specified probability level required for this identification Calculate the minimum number of simulation trials n according to the specified probability level; According to the minimum number of simulation tests, n simulation tests are performed to obtain a sample of propellant remaining quantity with a sample size of n, and the final stage safety margin of the propellant is simulated and calculated; Eliminate some of the minimum values ​​in the propellant remaining amount samples, and select the sample with the minimum propellant remaining amount from the remaining propellant remaining amount samples to calculate the rocket carrying capacity; The propellant includes a combustion agent and an oxidizer.

2. A method for evaluating the carrying capacity of a liquid rocket according to claim 1, characterized in that: Standard conditions include: rocket original data and deviation, target orbit parameters, geophysical parameters and standard atmosphere parameters.

3. A method for evaluating the carrying capacity of a liquid rocket according to claim 1, characterized in that: The remaining amount of the final stage propellant under zero interference conditions is specifically recorded as: The remaining amount of the final stage propellant under zero interference conditions M r0 , and the final oxidant residual amount M under zero interference conditions y0 .

4. A method for evaluating the carrying capacity of a liquid rocket according to claim 1, characterized in that: The minimum number of simulation tests n is calculated as follows: In the formula, γ is the confidence level; φ -1 is the inverse function of the normal distribution function; specify the probability level Determined by the overall appraisal unit; ζ is the requirement The relative accuracy achieved.

5. The method for evaluating the carrying capacity of a liquid rocket according to claim 1, characterized in that: According to the minimum number of simulation tests, the final stage safety margin M of the combustion agent is simulated and calculated. ra 、Oxidant final safety margin M ya The method is: Among them, M r0 is the remaining amount of propellant in the final stage under zero interference conditions, M y0 is the remaining amount of final stage oxidizer propellant under zero interference conditions; are the sample means of the remaining amount of the fuel and oxidant respectively; S r , S y are the standard deviations of the samples of residual fuel and oxidizer respectively.

6. A method for evaluating the carrying capacity of a liquid rocket according to claim 5, characterized in that: The average value of the remaining amount of the fuel and oxidant samples Standard deviation S of the remaining samples of fuel and oxidant r , S y The calculation method is: Among them, M ri 、M yi are respectively the remaining amounts of final stage fuel and oxidant in the i-th test.

7. A method for evaluating the carrying capacity of a liquid rocket according to claim 1, characterized in that: When removing some minimum values ​​in the propellant remaining amount samples, the method for determining the number of samples k that need to be removed is: For a given probability level, calculate:

8. A method for evaluating the carrying capacity of a liquid rocket according to claim 7, characterized in that: The method for calculating the rocket carrying capacity by selecting the sample with the smallest remaining amount among the remaining propellant remaining amount samples is: Select the smallest sample with the smallest remaining amount from the remaining nk propellant remaining amount samples; The calculation formula of carrying capacity is: Where M rP0 is the remaining amount of the sample fuel, M yP0 is the residual amount of oxidant, M z is the mass of the payload used in the standard trajectory calculation; λ0 is the conversion factor between the remaining available propellant and the carrying capacity of the rocket; M re is the unusable amount of fuel in the tank, M ye M is the unusable amount of oxidant in the tank; ra is the final stage safety margin of the propellant and the fuel, M ya It is the safety margin of the final stage of oxidizer propellant.

9. A terminal device, characterized in that: include: a memory for storing instructions executed by at least one processor; A processor, configured to execute instructions stored in a memory to implement a method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and when the computer instructions are executed on a computer, the computer is enabled to execute the method according to any one of claims 1 to 8.

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