RU2139438C1 - Solid-propellant rocket engine - Google Patents

Abstract

FIELD: construction of sustainer stages. SUBSTANCE: engine has casing with end plates, charge fastened with casing and provided with blind central passage. Charge is divided by combustible partition into two parts. Combustible partition is made in form of curvilinear surface with central hole symmetrical relative to longitudinal axis of engine. Cross-section area of partition decreases in way of rear end plate; front portion of charge and partition are fastened with front end plate. It is preferable to make partitions in form of truncated cone. Proposed engine may be used for high aspect ratio and low aspect ratio. EFFECT: enhanced efficiency of rocket engine due to reduction of stressed deformed state of charge in area of passage and in area of fastening the charge with casing; possibility of approaching engine charge-to-weight ratio to level of ratio of high stages. 2 cl, 4 dwg, 1 tbl

Description

 The invention relates to rocket technology and can be used in the design of the march stages of rocket engines on solid fuel (solid propellant rocket engine).

 The design of modern marching solid propellant rocket motors in most cases is based on channel structures of bulky charges of a cylindrical type with elliptical (filling the bottoms of the engine casing) ends (Fig. 1). Such charge designs make it possible to ensure that the engine fill factor with fuel is not more than 0.90 - 0.95 (M. Barrer et al., Rocket Engines, M, Oborongiz, 1962, p. 298).

 Further improvement of the weight characteristics (increase in the engine fill factor with fuel) of the charges of engines of large and medium elongations (the ratio of the length L to the radius of the body b is 3 ... 6) with a through channel can be realized due to the additional placement of fuel in the charge channel. A decrease in the channel diameter inevitably leads to an increase in the strength of the charge and unacceptably high requirements for the strength and deformation characteristics of the fuel used. The most rational in this case may be the use of cylindrical structures with a non-through channel.

 A known (Fig. 2) solid propellant rocket engine of small elongations, adopted for the prototype, comprising a housing with bottoms, a charge bonded to the housing, having a central through passage (Aerospace Daily, 1980, 5/11, vol. 101, N 25, p. 188 A - Russian translation of "Rocket and Space Technology" N 35, 1980, p. 12).

 An analysis of the applicability of such a monoblock design for charges of large and medium elongations showed that in this case, problems of strength character arise due to the presence of a concentration of strains at the apex of the blind channel. This zone becomes more dangerous (1.3 - 1.6 times) compared with the central region of the channel, which is associated with the need to fasten the front end of the charge to the bottom of the highly deformative body, which significantly loads the channel ending zone during engine operation.

 The objective of the proposed technical solution is to develop a solid propellant rocket engine having a charge with a non-through channel, which can be used in structures with medium and high elongations L / b - 3 ... 6 (first and second stages of solid propellant rocket engines), which increases the efficiency of using rocket systems due to reducing the stress-strain state of the charge in the channel zone and in the zone of charge bonding with the housing, and allowing at the same time to bring the engine fill factor to the achieved level with the fill factor of the high stages of 0.97 - 0.98.

The problem is solved by the claimed design of a solid propellant rocket engine containing a housing with bottoms, a charge bonded to the housing having a central through passage, the charge being divided by a partition into two parts, the partition is combustible, unfastened directly from the parts of the charge and made in the form of a curved surface with a central hole symmetrical about the longitudinal axis of the engine, the cross-sectional area of which decreases in the direction of the rear bottom, while the front h Part of the charge and septum are bonded to the front bottom,
It is preferable to make the partition in the form of a truncated cone.

 Distinctive features of the proposed design from the prototype are: separation of the charge into two parts, which cannot be removed after molding, which is burned off during operation of the engine by a partition that is not directly bonded to the fuel and bonded to the front bottom, with which the channel-free part of the charge is also bonded, the cross-sectional area of this part decreases towards the rear bottom.

 Thus, the inventive solid propellant rocket engine meets the criterion of "novelty."

 Comparison of the proposed solid propellant rocket engine with a prototype and other designs showed that there is no known technical solution in which the proposed combination of structural elements would take place. But it is precisely the combination of features that are distinctive from the prototype with the other essential features of the claimed invention that allows for a wide class of charges (L / b> 1) to achieve not only an increase in the engine fuel fill rate, as in the prototype, in comparison with standard designs with a through channel, but also simultaneously to reduce the stress-strain state of the charge in the central zone of the channel and in the zone of bonding of the charge with the housing.

 The effect of reducing the stress-strain state is achieved by eliminating the overhanging end surface and forming instead of it a recessed configuration of the front end of the back of the charge, realizing the possibility of mutual movement of the parts of the charge in the area of the partition.

 The proposed set of features makes it possible to make the best use of the internal volume of the engine body, use a muffled channel to accommodate more fuel in the structures of the first and second stages of medium and large elongation engines, and ultimately increase the efficiency of missile systems.

 This gives reason to consider the claimed technical solution as inventive.

 Placing an additional mass of fuel in the engine will increase the total thrust momentum for a given passive body weight or reduce the passive engine weight (by reducing its length) for a given charge mass. The consequence of this is an increase in the efficiency of solid propellant rocket engines in the form of an increase in flight range or payload weight. Reducing the stress-strain state of the charge will increase the warranty period of operation and the reliability of the solid propellant.

The invention is illustrated by drawings, which depict:
in FIG. 3 - longitudinal section of the engine;
in FIG. 4 is a diagram of the deformation of the proposed engine design under internal pressure loading.

 A solid propellant rocket engine contains a housing 1 with bottoms 2 and 3, a charge is fastened to the housing 1, the baffle 4 divides the charge into two parts 5 and 6, the rear part 6 of the charge has a central channel 7.

 The proposed design of a solid propellant rocket engine operates as follows.

 In the process of pre-launch operation, the partition 4, dividing the charge into two parts 5 and 6, reinforced with the housing 1, unloads it from the effects of temperature loads and mass forces due to the formation of a free zone for the charge change, adjacent to the partition 4.

 On the passive section of the engine flight, the charge parts 5 and 6 reinforce and encapsulate each other. Under the influence of axial overload due to deformation of the parts 5 and 6 of the charge in the area of the partition 4, a gap δ is formed. The shape change of the charge part 5 is thus restrained by fastening it to the surface of the front bottom 2.

 When the igniter (not shown) is ignited, the surface of the channel of the charge part 6 and the surfaces of the charge parts 5 and 6 adjacent to the partition 4 come through the cross section of the channel 7 and the gap δ from the igniter. The pressure arising inside the engine housing 1 from the incoming gases acts on the surface of the channel 7 and the surfaces of the charge parts 5 and 6 adjacent to the partition 4. The possibility of free deformation of the front end of the charge part 6 reduces the level of the deformed state in the zone of the channel 7.

 The implementation of various operating modes becomes possible due to the organization of combustion on the surfaces of the channel and the charge parts adjacent to the partition, variation of the open (unarmored) surface in the area of the partition and the rear end of the channel part of the charge.

 The main tool for optimizing the strength and intra-ballistic parameters of the claimed design is the linear size (along the axis of the engine) of the front of the charge, the diameter of the channel and the angular parameter of the partition, which divides the charge into two parts in the radial direction.

на канале и сдвиговых напряжений σ_ns в краевой зоне скрепления заряда с корпусом для трех типов конструкций двигателя (геометрические, жесткостные параметры и нагрузки для всех конструкций идентичны) представлены в таблице.In order to illustrate the effectiveness of the proposed technical solution, the results of the calculation of ring deformations

on the channel and shear stresses σ _ns in the boundary zone of the charge bonding with the casing for three types of engine structures (geometric, stiffness parameters and loads for all structures are identical) are presented in the table.

The calculation for the claimed design is made on the example of using a partition in the form of a truncated cone, in which the generatrix is at an angle of 45 ^o to the longitudinal axis of the engine.

An assessment of the effect of “undercutting” of the end of the rear part of the charge in the septum zone on the level of contact stresses σ _ns shows that the latter decreases by more than 2.5 times (4.51 / 1.49) compared with the convex ends characteristic of standard structures .

 From the analysis of the table it follows that in the design of an engine with a charge having a partition separating it into two parts, in the hazardous zones of the charge a lower level of stress and strain is realized while additional fuel is placed in the channel area (increase in the engine fill factor by 0.03 ) in comparison with the standard structures and its approximation to the achieved level of the coefficient of high steps.

 Bonded with the front bottom of the front channel-free part of the charge in the strength relation is a weakly stressed zone that does not regulate the operating conditions of a solid propellant rocket engine and the requirements for fuel characteristics.

 Thus, the proposed technical solution is practically feasible, the creation of such structures is an urgent and promising task, since in this case the efficiency of using missile systems is increased and, therefore, the claimed invention has industrial applicability.

Claims (2)

 1. A solid propellant rocket engine containing a housing with bottoms, a charge bonded to the housing, having a central through passage channel, characterized in that the charge is divided by a partition into two parts, the partition is combustible, unfastened directly from the parts of the charge and made in the form of a curved surface with a central hole symmetric with respect to the longitudinal axis of the engine, the cross-sectional area of which decreases in the direction of the rear bottom, while the front of the charge and the baffle are bonded with ne head.  2. The solid propellant rocket engine according to claim 1, characterized in that the partition is made in the form of a truncated cone.

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