RU167873U1 - BALLISTIC PENDULUM FOR DEMONSTRATION OF OPERATION MODES OF THE ROCKET ENGINE OF THE FUEL FUEL - Google Patents

Abstract

The utility model relates to teaching aids and can be used in the educational process to demonstrate the operating modes of a solid fuel rocket engine with specification of the characteristics of the modes. They supply power to the nichrome thread 4 and after some time to the ignition device of the test engine 1. The charge of solid fuel 3 ignites, which occurs the thrust pushes the massive platform 5, which on thin cables 6 freely rotates on the horizontal axis 7, the rotation angle of which is fixed by the angle sensor 8. At the same time measurement of the angle of rotation and pressure in the test engine 1 and registration by the apparatus unit occurs. With a sufficiently short burning time, the angular deviation of the pendulum is proportional to the total impulse of the reactive force. The technical result is the possibility of experimental study of the laws of the solid propellant rocket engine entering the main operating mode with the definition of the refined characteristic traction momentum.

Description

The utility model relates to teaching aids and can be used in the educational process to demonstrate the operating modes of a solid propellant rocket engine with specification of the characteristics of the modes.

A device for demonstrating operating modes of a solid fuel rocket engine containing an igniter, a charge, a combustion chamber, a nozzle unit, a thrust and pressure measurement system, is equipped with a pressure switch associated with a combustion chamber, the electrical contacts of which are connected in a circuit between an electric power source and a relay time, including an electromagnet, the rod of which is connected to one of the cams of the cam shaft, mounted on the front bottom of the combustion chamber, and the cams fix the closed the position of the hinged curtains, consisting of a front and rear walls, between which a steel ball is installed with a play, a clamping screw mounted on the front wall, and closing the draft shutoff windows located on the front bottom of the combustion chamber (RF Patent Utility Model No. 55472, 2006 )

A known installation for demonstrating operating modes of a rocket engine of solid fuel, containing a combustion chamber located on the slipway, a charge inside the combustion chamber, an igniter connected to the front end of the charge, a pressure measurement system suitable for the lower part of the combustion chamber, a nozzle, with the possibility articulated rotation around an axis fixed in the lower part of the combustion chamber, perpendicular to the axis of symmetry of the combustion chamber, and equipped with a hook rigidly mounted on the surface of the nozzle, diametrically perp peculiarly to the axis of rotation of the nozzle, which is pinched with a lever pivotally mounted on a bracket connected to the housing of the combustion chamber, a pendulum rigidly mounted on an arm mounted on the slipway, with the possibility of hitting the lever in the lower part of the pendulum trajectory, with a control panel fixed with the possibility of providing contact of electromagnetic detents, spring detent, movable contacts with the pendulum and the bath, with an igniter, with an electro-pneumatic valve in the charge ejection system located on the slipway, consisting of a stuffy balloon connected by a pipeline through a gearbox to a receiver, which, in turn, is connected by a pipe to an electro-pneumatic valve connected to a non-return valve, which is connected by a pipe to a nozzle placed tightly on the front end of the engine (RF Patent Utility Model No. 589825, 2006) .

The closest in technical essence solution is a ballistic pendulum containing a massive platform to which the test engine is attached, thin cables and a horizontal axis fixed in bearings, relative to which the pendulum can rotate freely, a track, a metal pin attached to the platform (B.V. Orlov , G.Yu. Masing. Thermodynamic and ballistic fundamentals of designing solid propellant rocket engines. Engineering Moscow, 1964. - 346 s).

The disadvantage of the prototype is the limited number of demonstrated modes of operation of a rocket engine of solid fuel and the inability to accurately determine their characteristics.

The objective of the utility model is to expand visual capabilities in the study of processes occurring inside a rocket engine of solid fuel, through the implementation of such a mode as the output of the engine with pressure pulsation, and the ability to determine the characteristics of the modes.

The technical result is the possibility of an experimental study of the laws governing the rocket engine of solid fuel to the main mode of operation with the determination of the updated characteristics of the thrust impulse.

The essence of the utility model is that in a ballistic pendulum for demonstrating the operating modes of a solid fuel rocket engine containing a massive platform to which the test engine is attached, thin cables and a horizontal axis fixed in bearings, relative to which the pendulum is mounted with free rotation, on a horizontal the axis of the rotation angle sensor is installed, the critical part of the nozzle of the test engine is removable, a nichrome coil is wound on the outer part of the solid fuel charge a thread.

The novelty lies in the fact that the rotation angle sensor is installed on the horizontal axis, the critical part of the nozzle of the tested engine is removable, a nichrome thread is wound on the outer part of the solid fuel charge.

The analysis of known technical solutions (analogues) in the studied area and related areas allows us to conclude that they lack features similar to the significant distinguishing features in the claimed device.

In FIG. 1 shows a general view of the device, FIG. 2 - laws of the solid propellant rocket engine entering the main mode: 1 - with pressure overload; 2 - design mode; 3 - with a pressure drop; 4 - pressure pulsation "sneezing".

The test engine 1, made of the housing 2, with a solid fuel charge 3 placed inside, on which a nichrome thread 4 is wound on the outside, is attached to the massive platform 5. The platform 5 is fastened through thin cables 6 with the possibility of free rotation on the horizontal axis 7, fixed in bearings with a mounted rotation angle sensor 8. A nozzle 9, the critical part of the nozzle of which is removable, and a pressure sensor 10 are mounted to the housing 2 of the test engine 1. The sensors of the rotation angle 8 and pressure 10 are connected to the register block uring equipment (not shown in Fig.).

The device operates as follows.

They supply power to the nichrome thread 4 and after some time to the igniter device of the tested engine 1. The charge of solid fuel 3 is ignited, the resulting thrust pushes the massive platform 5, which freely rotates on thin ropes 6 on the horizontal axis 7, the rotation angle of which is fixed by the rotation angle sensor 8 . In this case, the angle of rotation and pressure in the test engine 1 are measured and the equipment unit registers.

With a sufficiently short charge burning time, the angular deviation of the pendulum is proportional to the total momentum of the reactive force. The calculation formula for determining I by the measured deviation of the pendulum

where Q is the weight of the platform; L is the length of the pendulum suspension; K _τ - coefficient taking into account the duration of the reactive force; g is the acceleration of gravity; ϕ is the angle of rotation.

In addition to the refined characteristics of the thrust impulse when studying the processes occurring inside a solid propellant rocket engine, the ballistic pendulum makes it possible to experimentally study the laws of the solid propellant rocket engine entering the main operating mode. By varying the diameter of the critical part of the nozzle, as well as supplying power to the nichrome thread 4 or without supplying, various laws of the solid propellant rocket engine reaching the main mode are implemented, while experimentally determining the pressure in the combustion chamber.

When a solid propellant rocket engine enters the main operating mode with pressure overload (Fig. 2 curve 1), the formation of an undesirable pressure peak at the beginning of engine operation is usually associated with the thickness of the heated layer during the ignition period. If the heated layer formed during the ignition delay period is thicker than in the steady state, then the combustion of this layer immediately after ignition gives a more intense gas inlet, which may be accompanied by a pressure peak when entering the main mode.

When a solid fuel rocket engine enters the main mode of operation with a pressure drop (Fig. 2, curve 3), it occurs if the mass flow rate of the combustion products of the igniter is insufficient, but the amount of heat is sufficient to ensure starting.

The “sneezing” pressure pulsation (Fig. 2 curve 4) occurs if the amount of heat is supplied that is sufficient to ensure the start of the working process on the fuel surface, but not enough to self-sustain the combustion reaction (for example, at low, less critical, chamber pressures ) But since the surface layer is warmed up and the reactions occurring in it are exothermic, spontaneous combustion of the decomposition products and pressure surge can occur, but then the process will cease again, etc.

The proposed pendulum significantly expands the visual capabilities in the study of processes occurring inside solid propellant charges, provides visibility and the ability to observe and experimentally study the laws of the solid propellant rocket engine entering the main mode of operation, and at the same time calculate the experimental value of the updated thrust impulse characteristic.

Claims (1)

A ballistic pendulum for demonstrating the operating modes of a solid fuel rocket engine containing a massive platform to which the test engine is attached, thin cables and a horizontal axis fixed in bearings, relative to which the pendulum is mounted for free rotation, characterized in that the rotation angle sensor is mounted on the horizontal axis , the critical part of the nozzle of the test engine is made removable, a nichrome thread is wound on the outer part of the solid fuel charge.