CN-121997543-A - Tubular grain design method for impulse method combustion test

CN121997543ACN 121997543 ACN121997543 ACN 121997543ACN-121997543-A

Abstract

The invention provides a tubular grain size determining method for impulse method combustion test, which is characterized in that a mathematical relationship between a pressurizing rate and a propellant combustion characteristic relationship and a mathematical relationship between the pressurizing rate and a tubular charge size parameter are established, and the influence of the inner hole combustion tubular charge size on pressure change is revealed. The different requirements of the propellant impulse method combustion test on the shape size are clear. And the tubular charge design criterion which combines the test precision and the safety is provided by combining the constraints of the supercharging speed limit, the pressure test range, the erosion resistance combustion resistance and the like.

Inventors

WEI XIANGGENG
Cong Junhao
WANG YINGHONG
CHEN JIAN
SHI XU
HE GUOQIANG
YANG YUXIN
CHEN MAOLIN

Assignees

西北工业大学

Dates

Publication Date: 20260508
Application Date: 20251219

Claims (8)

1. The tubular grain design method for impulse method combustion test is characterized by comprising the following steps: Step 1, setting the throat diameter of the spray pipe According to the throat diameter of the spray pipe Calculating the area of the combustion surface of the propellant ; Step 2, calculating the minimum value of the area of the combustion surface of the propellant according to the requirements And obtain the lowest pressure Setting an initial value of the inner diameter d of the grain; step 3, calculating the length of the grain according to the minimum value of the area of the combustion surface of the propellant ; Minimum fuel surface area of propellant The method meets the following conditions: ; According to Calculating the length of the obtained grain ; If the length of the grain is 200Mm or more, considered as The diameter dt of the throat of the spray pipe is reduced by taking 0.2mm as the step length, the step 1 is returned, and the area of the combustion surface of the propellant is recalculated; If the length of the grain is The diameter d of the grain and the throat diameter of the spray pipe of the tubular charge are obtained when the diameter is smaller than 200mm And grain length ; Step 4, determining the outer diameter D of the grain according to the range of the pressure index; Step 5, according to the obtained grain outer diameter D, grain inner diameter D and grain length Calculating the pressurizing rate of the tubular charge, when the pressurizing rate is greater than or equal to 80% of the critical value of the pressurizing rate, considering that the pressurizing rate is too high, reducing the inner diameter d of the explosive column, reducing the step length of the inner diameter of the explosive column to be 2mm, jumping to the step 3 for recalculation, and when the pressurizing rate is smaller than 80% of the critical value of the pressurizing rate, considering that the pressurizing rate can meet the requirement of timely response of the pressure, and considering that the inner diameter d of the explosive column and the throat diameter of the spray pipe at the moment The length L of the explosive column and the outer diameter D of the explosive column are design parameters of tubular explosive charging, and the requirements of timely response of pressure intensity can be met.
2. The method for designing tubular grains for impulse combustion test according to claim 1, wherein the specific process of calculating the pressurizing rate in the step 5 is as follows: Differential the transient equilibrium pressure formula in the combustion chamber with respect to time, respectively, then the rate of pressurization Expressed as: (1) (2) in the formula, In order to achieve a rate of change of the combustion surface, D is the inner diameter of the grain, For the thickness of the meat burnt when the time is t, 0≤ Less than or equal to (D-D)/2, wherein D is the outer diameter of the grain, and L is the length of the grain; N is the pressure index; Is the propellant density; Is a characteristic speed of the propellant; for the area of the combustion surface of the propellant, Is the throat area of the spray pipe; Namely there is (3) Wherein the method comprises the steps of Is the rate of pressurization.
3. The method for designing a tubular grain for impulse combustion test according to claim 2, wherein the step of obtaining the critical value of the supercharging rate is: step 5-1, obtaining the combustion speed change rate of the propellant under the existence of the pressurizing rate; The combustion speed change rate is the ratio of the difference between the static pressure combustion speed and the dynamic pressure combustion speed to the response time of the dynamic pressure combustion speed, and the static pressure combustion speed of the propellant under constant pressure is The corresponding dynamic pressure burning speed is that when the pressure is changed rapidly Dynamic pressure burning speed slave Becomes as follows Is time-consuming in the process of I.e. Response time for dynamic pressure burn rate; Is the combustion rate coefficient; is the pressure intensity; The static pressure burning rate of the propellant under constant pressure is ; The corresponding dynamic pressure burning speed is that when the pressure is changed rapidly Dynamic pressure burning speed slave Becomes as follows Is time-consuming in the process of I.e. Response time for dynamic pressure burn rate; The rate of change of the combustion speed The method comprises the following steps: ; Wherein the method comprises the steps of N is the pressure index; the response hysteresis degree of the dynamic pressure burning speed to the pressure change is represented; S5-2, performing term transfer on the expression of the combustion speed change rate to obtain dynamic pressure combustion speed and a dynamic relation between the combustion speed change rate and pressure; Rate of change of combustion speed The expression of (2) is subjected to term transfer to obtain dynamic pressure burning speed and dynamic relation of burning speed change rate and pressure: The dynamic relation between the dynamic pressure burning speed, the burning speed changing speed and the pressure is a classical first-order dynamic differential equation, the dynamic relation between the dynamic pressure burning speed, the burning speed changing speed and the pressure is a first-order inertia link, when the pressure is unchanged, namely When the Viyer equation is equivalent to the dynamic pressure burning speed and the dynamic relation between the burning speed changing rate and the pressure; S5-3, determining boundary conditions of dynamic pressure burning speed and timely response pressure change; At a rate of pressurization When larger, due to Is greater than zero, so the combustion speed of the dynamic pressure and the dynamic relation between the combustion speed change rate and the pressure are obtained The dynamic pressure burn rate at which the boost rate exists is therefore less than the static pressure burn rate at steady state, and therefore appears to be when the boost rate When the dynamic pressure burning speed is larger, the dynamic pressure burning speed response is lagged; in order to ensure that the dynamic pressure burning speed timely responds to the change of the pressure, the boundary conditions for determining the dynamic pressure burning speed timely responding to the change of the pressure are as follows: When the requirement of timely responding to the pressure change boundary condition of the dynamic pressure burning speed is met, the dynamic pressure burning speed can timely respond to the pressure change, namely the Viyer equation is equivalent to the dynamic pressure burning speed and the dynamic relation between the burning speed change rate and the pressure; S5-4, deriving time by a Viyer equation according to a boundary condition that dynamic pressure burning speed timely responds to pressure change, and obtaining a boundary condition of a supercharging rate; Deriving time from the Viyer equation: the boundary conditions for bringing the result obtained by deriving the time from the Viwill formula into the dynamic pressure burning speed and responding to the pressure change boundary conditions in time to obtain the supercharging speed are as follows: S5-5, determining a critical value of the supercharging speed and a supercharging speed interval; the product of the change rate of the burning rate and the response time of the dynamic pressure burning rate is smaller than the dynamic pressure burning rate Is critical, i.e Calculating the critical value of the pressurizing rate to be I.e. A pressurizing rate interval for timely responding the dynamic pressure burning speed of the propellant to the pressure; the threshold value of the boost rate is: the minimum time interval for the combustion speed measurement based on the impulse method is 0.05s, so the combustion speed response time is required Not more than 0.005s, which was adopted in the present study The combustion speed of the propellant is considered to be in time response to pressure change within 0.005s as a reference value, and the value ensures the applicability of calculation of the critical supercharging speed and can meet the combustion speed detection requirement of most propellants, wherein the unit of the critical supercharging speed is MPa/s.
4. The method for designing tubular grain for impulse combustion test according to claim 1, wherein the nozzle throat diameter The initial value of (2) is 7mm.
5. A method of designing a tubular charge for an impulse combustion test as claimed in claim 1, wherein said minimum pressure is obtained The method comprises the following steps: Will minimum burning rate Coefficient of combustion speed Pressure index n, propellant density Minimum value of propellant combustion area Throat area of nozzle And characteristic speed of propellant Transient equilibrium pressure expression brought into combustion chamber to obtain minimum pressure Minimum pressure intensity Minimum pressure below demand 。
6. The method for designing a tubular grain for impulse combustion test according to claim 1, wherein the step of determining the grain outer diameter D according to the range of the pressure index is: Calculating a first candidate outer diameter according to a transient balance pressure formula ; When the pressure index n is less than or equal to 0.38, calculating the second candidate outer diameter The method comprises the following steps: Wherein The first meat thickness is in the range of: ≥15mm; The grain outer diameter D is: ; When the pressure index is in the range of 0.38< n≤0.55, calculating a second candidate outer diameter The method comprises the following steps: , the second meat thickness is in the range of: ≥20mm; The grain outer diameter D is: ; when the pressure index n >0.55, the tubular charge fails to meet the design requirements.
7. A terminal device comprising a processor, a memory and a computer program stored in said memory, characterized in that the processor, when executing the computer program, implements a tubular grain design method for impulse method combustion testing according to any one of claims 1-6.
8. A computer readable storage medium, in which a computer program is stored, characterized in that the computer program, when being executed by a processor, implements a tubular grain design method for impulse method combustion testing according to any one of claims 1-6.

Description

Tubular grain design method for impulse method combustion test Technical Field The invention belongs to the technical field of dynamic testing of combustion performance of solid propellant, and mainly relates to a tubular grain design method for impulse method combustion test. Background The burning rate of solid propellant is a key parameter characterizing its combustion characteristics, directly affecting the working performance of rocket engines. The burning rate is defined as the distance of the combustion surface of the propellant charge moving back in unit time along the normal direction of the propellant charge, and determines the energy release rate and is used as the calculation reference of the burning performance such as the burning rate coefficient, the pressure index, the temperature sensitivity coefficient, the erosion ratio and the like. In the literature 'impulse method for testing the high-pressure dynamic combustion speed and pressure index of a solid propellant' (the "explosive and powder school journal, 2019 (03), 278-283) and the patent 'impulse method for testing the validity of raw data of the solid propellant combustion speed' ZL202110283176.2,2022.3, a high-efficiency test method for dynamically testing the combustion speed of the solid propellant by the impulse method is provided, a tubular charge with an inner hole for combustion is adopted, a thrust-time curve and a pressure-time curve which are increased with time are obtained, and the combustion speed under any pressure in a pressurizing range can be measured by a single test. The impulse method fuel rate test has the precondition that the bare inner hole can be synchronously ignited, and the fuel rate can respond to the change of pressure in time. ZL202110283176.2,2022.3 gives a criterion for ignition synchronism. The tubular charge with the combustion of the inner hole can ensure the ignition synchronism of the exposed initial combustion surface, and has the advantages of simple structure, high combustion speed coupling calculation efficiency and the like. However, a specific determination method of the size of the tubular grain is not provided, so that the propellant with low combustion speed and low pressure index has a small supercharging range and is insufficient for realizing the purpose of high-efficiency test of the combustion speed, and the propellant with high combustion speed or high pressure index has the problem that the combustion of the propellant cannot respond to the change of the pressure in time although the supercharging range is large. Disclosure of Invention In order to overcome the defects of the prior art, the invention provides a tubular grain design method for impulse method combustion test, which aims at solving the problems that the propellant with low combustion speed and low pressure index has a small supercharging range and is insufficient for realizing high-efficiency test of the combustion speed and high combustion speed or high pressure index has a large supercharging range, but the propellant combustion cannot respond to the change of pressure in time. The tubular grain design method for impulse method combustion test comprises the following steps: Step 1, setting the throat diameter of the spray pipe Is the initial value of (2); according to the throat diameter of the spray pipe Calculating the area of the combustion surface of the propellant; Step 2, calculating the minimum value of the area of the combustion surface of the propellant according to the requirementsAnd obtain the lowest pressureSetting an initial value of the inner diameter d of the grain; step 3, calculating the length of the grain according to the minimum value of the area of the combustion surface of the propellant ; Minimum fuel surface area of propellantThe method meets the following conditions:; According to Calculating the length of the obtained grain; If the length of the grain is200Mm or more, considered asThe diameter of the grain of the tubular charge is too large and too small, at the moment, the throat diameter dt of the spray pipe is reduced by taking 0.2mm as the step length, and the step 1 is returned to for recalculation; If the length of the grain is The diameter d of the grain and the throat diameter of the spray pipe of the tubular charge are obtained when the diameter is smaller than 200mmAnd grain length; Step 4, determining the outer diameter D of the grain according to the range of the pressure index; Step 5, according to the obtained grain outer diameter D, grain inner diameter D and grain length Calculating the pressurizing rate of the tubular charge; Differential the transient equilibrium pressure formula in the combustion chamber with respect to time, respectively, then the rate of pressurization Expressed as: (1) (2) in the formula, In order to achieve a rate of change of the combustion surface,D is the inner diameter of the grain,For the thickness of the meat burnt when the time is t, 0≤Less than