RU2168648C1 - Ballistite solid propellant rocket engine - Google Patents

Abstract

FIELD: rocket engines. SUBSTANCE: rocket engine with inserted charges in form of cylindrical grain with central star-shaped channel over entire length working in wide temperature range from -50 C to +60 C; at stress concentration factor at vertices of charge beams ranging from 1.3 to 2.2, solid propellant has standard modulus of elasticity at high temperature of engine combat use within range of 2,1P $\genfrac{}{}{0ex}{}{\text{+60}}{\text{max}}$ ≅ E $\genfrac{}{}{0ex}{}{\text{+6}}{\text{СТ}}$ ⁰ ≅ 3,3P $\genfrac{}{}{0ex}{}{\text{+60}}{\text{max}}$ , where E $\genfrac{}{}{0ex}{}{\text{+6}}{\text{СТ}}$ ⁰ is standard modulus of elasticity of propellant at temperature of 60 C, MPa and

Description

 The invention relates to the field of rocket technology and can be used in the design, development and manufacture of solid propellant rocket engines with external charges of ballistic solid fuels (BTT) for engines of various functional purposes and, in particular, for engines of active reactive systems (ARS) and anti-tank systems (ATGM).

 The specifics of the operation of the auxiliary charge of the APC and ATGM systems impose stringent requirements on its mechanical, energy and physico-mechanical characteristics of solid rocket fuel (TRT), which ensures reliable engine performance in the required operating and combat use conditions. These conditions include temperature differences during long-term storage, transport loads, the effects of axial and radial pressure drops inside the engine housing during its operation, axial and lateral overloads during the flight of the product.

 The structural design of an engine with a freely inserted plug-in charge is classical (see, for example, Shapiro Ya.M., Masing G.Yu., Prudnikov I. N. "Fundamentals of designing solid-propellant rockets." Military Publishing House M.O., M ., 1968, p. 38. Fig. 1.35). In the diagram of Fig. 1.35 is a solid propellant solid propellant rocket with a freely enclosed armored charge burning along a cylindrical channel, which cannot provide high thrust-to-weight ratio of the engine (with the required short operating time), especially for ARS and ATGM systems.

 The closest in technical essence and the achieved result is a solid fuel rocket engine (solid propellant rocket engine), schematically shown in FIG. 10.16 in the book of A.M. Vinnitsky "Solid propellant rocket engines", Engineering, M, 1973, p. 293, which is taken as a prototype. The prototype engine design is a solid propellant solid propellant solid propellant solid propellant solid propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant solid-propellant combustion engine with a slotted notch along the entire charge length, which provides a developed combustion surface, especially at the initial moment of engine operation and, therefore, high engine thrust ratio (See Fig. 1 is a prototype).

The main disadvantage of the design of the engine adopted for the prototype is as follows. As a rule, the temperature range of the engine’s combat operation is significantly higher than the natural climatic one and ranges from minus 50 ^o C to plus 60 ^o C, therefore there are cases of charge destruction due to an insufficient level of mechanical reliability (probability of failure-free operation in strength) as in the zone of the upper temperature range of use , and in the zone of the lower range, which ultimately leads to a partial destruction of the charge and a decrease in the total impulse of engine thrust, and in some cases even to complete destruction of the engine. In FIG. Figure 2 shows the experimental diagrams "pressure (thrust) - time" tests of a typical engine at various temperatures.

(1) + 20 ^o C - normal engine operation;
(2) + 60 ^o C - work with partial destruction of the charge at the end of engine operation;
(3) - 50 ^o C - work with partial destruction of the charge at the beginning of engine operation.

(4) - complete destruction of the engine
In variants (2) and (3), the total impulse of the engine thrust decreases (the area bounded by the ≪R-τ≫ curve) and the specified energy characteristics of the engine are not provided.

The objective of the invention is to provide ballistic characteristics of the engine due to the high level of mechanical reliability of the charge. The problem is solved due to the fact that in a solid propellant rocket engine with an all-round insertion charge in the form of a cylindrical checker made of ballistic solid fuel with a central star-shaped channel over the entire length, operating in a wide temperature range of military applications from minus 50 ^o C to plus 60 ^o C , at stress concentration factors at the tops of the charge rays of 1.3 ... 2.2, solid fuel at the top temperature of the combat use of the engine has a standard modulus of elasticity defined in the range:
2.1P _max ⁺⁶⁰ ≅ E _Art ⁺⁶⁰ ≅ 3.3P _max ⁺⁶⁰ ,
where E _article ⁺⁶⁰ - standard modulus of elasticity of the fuel at a temperature of 60 ^o C, MPa.

P _max ⁺⁶⁰ - the maximum pressure in the engine at a temperature of 60 ^o C, MPa.

 The design of the inventive engine is shown in FIG. 3.

 The proposed design consists of a housing 1, a charge of solid fuel 2, an igniter 3, a support grid 4, a nozzle 5.

The processing of a large amount of experimental material for testing systems with engines containing all-round insertion charges with a star-shaped channel from various ballistic solid fuels for missiles and shells of aircraft systems, active-reactive systems (ARS), ATGMs, and general army weapons showed:
1. In the area of the lower range of combat use (minus 50 ^o C ... minus 20 ^o C) there is a partial destruction of the fuel checkers in the region of the ends of the charge (chips) due to dynamic impacts on the support grids when the igniter, axial and transverse overloads, which are maximum in the initial period of the engine of the considered classes of shells and missiles.

где σ - эксплуатационное напряжение в шашке, МПа;
ε_ст - деформация топлива при стандартной скорости нагружения, %.Chips occur due to high fuel hardness at low temperatures. Fuel stiffness is characterized by a standard modulus of fuel elasticity

where σ is the operational voltage in the checker, MPa;
ε _st - fuel deformation at standard loading rate,%.

 Partial destruction of the checkers of fuel and the flight of fuel through the nozzle leads to a decrease in the total impulse of engine thrust.

2. In the field of high positive temperatures for military use (+40 ... +60 ^o C), partial destruction occurs due to the minimum fuel strength (minimum rigidity, since the standard modulus of elasticity of the fuel is directly correlated with the strength of the fuel) and the concentration of operational stresses at the tops of the rays of a star-shaped profile. The stress concentration coefficient at the vertices of the rays of a star-shaped profile is defined as the ratio of the equivalent operational voltage (σ _equiv ) at the top of the beam to the rated voltage (σ _nom ) in a charge with a round channel with a radius equal to the radius of the vertex of the rays (see I.Kh. Fakhrutdinov, A .V. Kotelnikov "Design and Design of Solid Fuel Rocket Engines", Mechanical Engineering, Moscow, 1987, p. 199).

 The scheme for calculating the stress concentration coefficient is shown in FIG. 4.

For the designs of charges investigated in this technical solution, the concentration coefficient is in the range 1.3 ... 2.2. The experimentally established range of hard fuel stiffnesses, providing the ballistic characteristics of the engine due to the high level of mechanical reliability of the charge, is:
2.1P _max ⁺⁶⁰ ≅ E _Art ⁺⁶⁰ ≅ 3.3P _max ⁺⁶⁰ ,
where E _article ⁺⁶⁰ - standard modulus of elasticity of the fuel at a temperature of 60 ^o C, MPa.

P _max ⁺⁶⁰ - the maximum pressure in the engine at a temperature of 60 ^o C, MPa.

 The restriction on the minimum permissible value of the standard module provides the required engine performance in the high temperature zone due to the lack of partial destruction of the fuel checkers at the end of engine operation. The restriction on the upper limit of the standard module ensures non-destruction of the fuel checkers at the initial moment of engine operation in the region of negative temperatures.

Recalculation of the standard module at various temperatures is carried out according to the generally accepted formula:
E _article ^t = E _article ⁺²⁰ • [1 - K (T-20)],
where E _article ⁺²⁰ - standard modulus of elasticity of the fuel, determined at 20 ^o C;
K is an empirical coefficient;
T - temperature combat use, ^o C.

- точечной оценки вероятности выполнения внутрибаллистических характеристик двигателя, которая должна быть не ниже 0,993 (правило трех сигм для нормального закона распределения).The graphically set limitation range of the standard modulus is illustrated in FIG. 5 graph of parameter change

- a point estimate of the probability of performing the ballistic characteristics of the engine, which should be at least 0.993 (three sigma rule for the normal distribution law).

 The established ratios of the standard module are introduced into the technical documentation for charges from ballistic solid fuels, which made it possible to ensure the required reliability of the engines.

Claims (1)

A solid propellant rocket engine with an all-round insertion charge in the form of a cylindrical checker made of ballistic solid fuel with a central star-shaped channel over the entire length, operating in a wide temperature range of military applications from minus 50 ^o C to plus 60 ^o C, characterized in that at concentration ratios stresses at the tops of the charge rays 1.3 - 2.2 solid fuel at the top temperature of the combat use of the engine has a standard modulus of elasticity, set in the range:
2.1P _max ⁺⁶⁰ ≅ E _CT ⁺⁶⁰ ≅ 3.3P _max ⁺⁶⁰ ,
where E _CT ⁺⁶⁰ is the standard modulus of elasticity of the fuel at a temperature of 60 ^o C, MPa. P _max ⁺⁶⁰ - the maximum pressure in the engine at a temperature of 60 ^o C, MPa.

Images