RU2409756C1 - Method of testing solid rocket propellant charge - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: proposed method comprises fitting the charge in solid-propellant rocket engine combustion chamber and thermostatting said charged engine at the temperature of accelerated climatic tests. Period of thermostatting is determined with due allowance for solar radiation effects by relationships protected by this invention. Then, solid-propellant rocket engine is disassembled to check the charge for integrity. Thereafter, charge is fitted again in the engine to perform firing trial for compliance with technical requirements.

EFFECT: higher accuracy of estimating serviceability in accelerated climatic tests of slid-propellant charge.

3 dwg, 2 tbl

Description

The patented invention relates to the field of rocket technology and can be used in the design, development and testing of solid propellant rocket engines (solid propellant rocket engines) and solid rocket propellant charges (TRT) to them.

To determine (and confirm) the term of serviceability (the term of serviceability is the time interval during which the product meets the requirements specified in the design documentation (drawing, technical conditions) under actual operating conditions.) Solid propellant rocket motors and TRT charges are known for the method of accelerated climate tests (USP) the latter by prolonged thermostating (aging) at elevated temperature, which is based on compliance with the principle of temperature-time equivalence in relation to real product operating conditions (in a temperate climate, humid and dry tropical climate, etc. in accordance with GOST 15150-69, GOST 24482-80). In this method, the concept of equivalent temperature (T _equiv ) is used, which means a conditional constant temperature at which the same changes occur in the system during the considered time as in natural environmental temperature conditions.

Loss of serviceability of the TPT charge during the required warranty period of storage (GC) and operation (serviceability period) can occur for various reasons, the main of which are:

1. Chemical transformations in the TPT system (composition), for example, associated with the thermal decomposition of nitroesters in the composition of ballistic fuels or a binder in the composition of mixed solid fuels, which leads to a decrease in the rate of combustion of the TPT (Fig 1), as well as the output characteristics of the solid propellant rocket engine (thrust level, thrust momentum).

2. In the presence of armor plating (BP) in the charge structure - diffusion processes in the system "TRT - armor plating" (Pat RU 2154616, 2241845). The latter lead to a loss of energy, for example, ballistic TPT due to the diffusion of nitroglycerin (NG) in the armor coating, and to an increase in the flammability of BP saturated with NG, which, in turn, leads either to an off-balance burnout of BP (Figure 2), or to increased smoke formation of the charge in the conditions of active combustion of the PSU, which significantly complicates the guidance of the rocket at the target.

3. The decrease in the level of physical and mechanical characteristics of TRT, due to the above chemical and diffusion processes, up to the mechanical destruction of the charge (cracking).

As a technical analysis showed, all these reasons for the loss of serviceability of the TRT charge, in terms of the process dynamics (speeds of various chemical and physical processes), are described by the well-known Arrhenius dependence, which allows us to obtain a general relation for T _equiv (source: Physicochemical Mechanics Materials ”, Volume 13, No. 1, 1977,“ The Science of Duma ”, Kiev, B.D. Goikhman, T. P. Smekhunova, pp. 92-97)

Where

E-activation energy, cal / mol;

R-universal gas constant, cal / mol · K;

τ _{0 is the} service life of the charge, day;

T _{i is the} average temperature for the interval Δτ _i , K;

n is the number of time intervals with an average temperature T _i during the service life of the charge;

Δτ _i - the time interval during which the temperature T _i in accordance with GOST 24482-80, a day.

The indicated relation [1] for T _equiv characterizes the aging process of TPT charges in terms of a specific physicochemical process with a corresponding activation energy level (E). However, under real operating conditions of anti-aircraft guided missiles (SAM), aircraft missiles (AR) and some other missiles, they, and consequently, solid propellant rocket launchers and TRT charges, may have a certain “life” time (for example, standby time for air defense systems) solar radiation (missiles - on the open guides of launchers, AR - docked to the fuselage of the carrier aircraft in the open area of aerodromes). However, the indicated ratio in the form [I] does not take into account the influence of solar radiation, which sometimes creates a short-term, but very significant additional thermal load, which can lead to a loss in the operational characteristics of the TRT charge.

The analogues of the patented invention are: US Pat. RU 2217746 C1, ist. Design and development of solid propellant rocket engines, ed. A.M. Vinnitsky, M.: “Engineering”, 1980, pp. 207-210, SU 1133507 A, RU 2018 826 C1, RU 2056636 C1, DE 1275807 V.

The closest analogue to the patented solution is the invention according to US Pat. RU 2217746 C1 (application 2002105234 dated 02.26.2002, IPC G01N 33/22, F42B 35/00), selected by the authors for the prototype.

The technical task of the patented invention is to develop an effective method of accelerated climate testing (USP) of the charge of TRT to confirm the service life of the charge in natural temperature conditions, taking into account the effects of solar radiation.

The technical result of the invention consists (Fig. 3) in a method for testing the charge of TRT in a solid propellant rocket motor, taking into account the effect of solar radiation in confirmation of the useful life. The method includes charging the charge (5) into the combustion chamber (6) of the solid propellant rocket motor, temperature control of the charge at an ultrashort pulse temperature T _y , for example 333 K, for a period of time τ _y determined taking into account the equivalent temperature, according to the ratio

disassembling solid propellant rocket motors and external inspection of the charge for mechanical damage. In the absence of mechanical destruction of the charge (cracks), the charge is re-collected in the solid propellant rocket engine, equipped with the solid propellant rocket igniter and a pressure recording sensor in the combustion chamber, and fire test bench charge is carried out in the solid rocket motor at extreme temperatures of operation of the charge, for example, 323 K and 273 K for compliance with the requirements documentation for a given pressure level (p) and the nature of the pressure-time relationship. In this case, T _equiv is determined by the ratio

where Δτ _1i = Δτ _i -τ _c / kn,

Δτ _1i is the time interval with air temperature T _i without taking into account the time of action of solar radiation, day;

τ _c - total time of action of solar radiation over the service life of the charge, day;

“T _i +30” - the average temperature under the action of solar radiation during the service life of the charge, K (according to GOST 24482-80, it is envisaged to take into account solar radiation when assessing the shelf life of products, by increasing the average temperature T _i by 30 degrees);

to - the service life of the charge, year.

In this case, the temperature of the ultrashort pulse T _y is preferably set to 333 K, the level of which, on the one hand, is usually close to the upper temperature limit of operation, and on the other hand, “minimally” affects the nature of the kinetic processes in the TRT formulations and armored coatings (BP), and in mutual diffusion processes in the TRT-BP system, compared with their occurrence at higher temperatures (for example, 338 K, 343 K).

The patented method is illustrated in the figures:

Figure 1 - Dependence of the rate of combustion of TRT

1 - for the original ("fresh") TPT;

2 - for TRT subject to aging during operation (storage);

Figure 2 - Dependence "pressure-time" - p (τ)

3 - non-calculated pressure-time relationship (due to burnout of armor plating);

4 - calculated dependence;

Figure 3 - Technological scheme of the ultrashort pulse of the patented method

5 - charge TRT;

6 - combustion chamber of the solid propellant rocket engine.

The essence of the invention is to take into account the effect of solar radiation on the charge of TRT when determining the equivalent temperature T _equiv , the features of which are as follows:

1) The total time of exposure to solar radiation (τ _c ) is distributed evenly for each year from the assigned service life (service life) - τ _c / k. At the same time, it is taken into account that the annual change in the ambient temperature is practically systematically repeated.

2) Determine the time of exposure to solar radiation on the TRT charge in each time interval (Δτ _i ) during which the temperature T _i in accordance with GOST 24482-80 - τ _s / kn. At the same time, we take into account that the time interval with the same temperature T _i covers different seasons of the year, therefore, a uniform distribution of the time of action of solar radiation over all n intervals is the most probable, corresponding to real conditions;

3) For each time interval Δτ _i , the time (Δτ _1i ) is determined without taking into account the time of exposure to solar radiation according to the ratio:

Δτ _1i = Δτ _i -τ _c / kn.

4) T _{eq is} determined taking into account the effect of solar radiation by the relation [3] and the required time of long-term thermostating τy is determined taking into account the selected elevated temperature T _y by the relation [2].

In general, with the indicated procedure for determining T _eq, the principle of equal probability of combining (applying) the natural temperature distribution over the duration of the serviceability period for a given climatic region according to GOST 24482-80 and the direct effect of solar radiation on charge (as part of solid propellant rockets, rockets) is observed.

USP, taking into account the effects of solar radiation, according to the patented method are carried out in the manner indicated on the technological scheme (Fig 3).

An example implementation of the method:

The total service life of the TRT charge as a part of the solid propellant rocket motor is set - three years when operated in a dry tropical climate. The total charge operating time (as a part of the solid propellant rocket motor) under the influence of solar radiation during the service life of the charge is 100 hours (4.17 days). It is required to confirm the service life of the charge by accelerated climatic tests at elevated temperatures.

The value of the increased temperature T _y when confirming the USP is selected, for example, T _y = 333 K. Based on the data of GOST 24482-80, to calculate the equivalent temperature (taking into account the time of exposure to a temperature increased by 30 ° C due to solar radiation), Table 1 is compiled parameters for a given climatic region - with a dry tropical climate excluding solar radiation, as well as an auxiliary temperature-time table 2 (taking into account solar radiation and in accordance with GOST 24482-80 with an increase of 30 degrees for a given period of exposure to solar radiation).

Substituting the numerical values of the parameters from Table 2 into the relation [3], determine the value of T _eq for a given climatic region of operation of solid propellant solid propellant rocket (charge TRT) taking into account solar radiation, as well as the duration of temperature control τ _y :

T _equiv = 309 K; τ _y = 18.65 days (at T _y = 333 K)

Taking into account the indicated parameters T _equiv τ _y , a USP of the charge (Fig. 3) from ballistic TRT was carried out, including, in addition to determining the parameters T _eq and τ _y , charge equipment (5) in the combustion chamber (6) of the solid propellant solid propellant, charge temperature control in the sealed solid propellant within 19 days at T _y = 333 K. After thermostating according to the indicated mode, the solid propellant was disassembled, the charges were inspected for defects and the charge remained solid. There were no defects, the charges remained solid. The solid propellant rocket engine was reassembled with charge and subjected to fire tests at T = 323 K to obtain ballistic characteristics close to the calculated pressure-time dependences p (τ) thrust-time R (τ) corresponding to the given requirements.

The positive effect of the invention is to increase the objectivity (reliability) of evaluating the service life of the TRT charge, taking into account the direct impact of solar radiation on the total operational resource of the TRT charge, which improves the reliability of the TRT (RDTT) charges and missile systems in general, especially for conditions of heat-stressed (tropical) ) climate, in terms of ensuring the required terms of serviceability.

Claims (1)

A method of testing the charge of solid rocket fuel to confirm the service life of a rocket engine of solid fuel, including equipping the charge in the combustion chamber of a rocket engine of solid fuel, temperature control at an accelerated climate test (Tu) temperature of a solid rocket engine charged with a charge, and conducting a rocket engine fire test solid fuel for compliance with the requirements of technical documentation, characterized in that the temperature control time τ _y determined taking into account the ratio:

in which, in order to be able to take into account the effects of solar radiation, the equivalent temperature is determined by the ratio:

where T _equiv - equivalent temperature, K;
E - activation energy, cal / mol;
R is the universal gas constant, cal / mol · K;
τ ₀ - the service life of the charge, day;
n is the number of time intervals with an average temperature T _i during the service life of the charge;
Δτ _1i = Δτ _i -τ _c / k · n is the time interval during which the temperature T _i is valid without taking into account the time of action of solar radiation, days;
Δτ _i - the time interval during which the temperature T _i , days;
T _i is the average temperature for the time interval Δτ _i , K;
τ _c - total time of action of solar radiation over the service life of the charge, days;
to - term of serviceability, years,
moreover, after thermostating, the rocket engine of solid fuel is disassembled and the charge is examined with an assessment of its monolithicity, then the charge is re-equipped in the rocket engine of solid fuel, and then the rocket engine of solid fuel is fired.

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