RU2574778C2 - Demonstration of intraballistic and power characteristics of solid-propellant rocket engine charge and test bench - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: at demonstration of said characteristics, the run of charges with different combustion rate are fired in simulator chamber with round discharge opening of critical throat and pressure is measured therein. Before firing, said charge is thermostated to the temperature that ensures the charge firing rate and pressure with minimum departure from their ratings and defined by the formula protected by this invention. Test bench comprises metallic ramp with horizontal swing plate for attachment of simulator chamber with discharge round opening of critical throat, pressure transducer and meter of the force between swing plate and the ramp. Said ramp has vertical thrust wall for bracket with bearing assembly to be secured thereat to support the swing plate vertical shaft. Force meter is secured at said ramp vertical thrust wall to contact with swing plate side surface. Swing plate and ramp vertical thrust wall are coupled in horizontal plane by coiled spring for initial pressing of the ramp swing plate to said force meter. Swing plate under simulator chamber has vertical posts to contact with the test bench floor via end bearings their axes being perpendicular to force meter axis. Simulator chamber is enclosed in heat-insulated jacket and pipe with nozzle, its axis being parallel with force meter axis. Axes of pipe with nozzle and force meter are perpendicular to the ramp vertical thrust wall.

EFFECT: decreased error of demonstration.

4 cl, 6 dwg

Description

The present invention relates to rocket technology and can be used in the development of a solid fuel charge for an engine in the design of which a limit valve is provided to ensure that the pressure in the combustion chamber is over pressure.

The solid fuel of such engines is characterized by a high sensitivity of the burning rate "u" to the pressure p _k in the combustion chamber (u = u ₁ · p ^ν , where u ₁ is the coefficient corresponding to a specific fuel, ν is the exponent in the law of the burning rate, ν ~ 0 , 6 ... 0.7) and a large spread of the burning rate "Δu" from the nominal Δu ~ 10 ... 15% for charges in different batches of manufacture, which creates significant difficulties in confirming the required flow characteristics of the gas "G _τ " and ballistic characteristics (VBH) generally.

Currently, when developing such charges, a simulator chamber is used with different critical sections of the outlet depending on the rate of burning of the charge determined in the constant pressure device (PPD) for each batch of charges. For example, a series of 10 nozzles is used, each of which corresponds to a certain range of combustion speeds and serves to not exceed the maximum pressure and ensure minimum pressure deviations from the nominal value. Moreover, to accurately determine the characteristics of the camera-simulator does not contain a pressure regulator.

The principle of using different critical sections of the outlet nozzles (nozzle regulation) depending on the charge temperature to ensure that the pressure in the combustion chamber is not exceeded is given, for example, in book. "The theory of a solid propellant rocket engine", authored by Shapiro Ya.M., Masing G.Yu., Prudnikov N.E., M. 1966, Military Publishing House of the Ministry of Defense of the USSR, p. 172 ... 177.

When using a set of nozzles for testing engine charges, an additional error is created in determining the scatter of ballistic characteristics, including in the analysis of abnormal fire bench tests (AIS), because the total pressure impulse (J _Pк ) in the combustion chamber changes, which makes it impossible to accurately assess the change in the ballistic and energy characteristics (VBH and EC) of the engine.

The objective of the invention is to provide a test method that can significantly reduce the error in determining the VBH and SEC of a rocket engine.

This task is carried out due to the fact that in the known method of confirming the ballistic and energy characteristics of the solid propellant charge of a rocket engine, which consists in burning a series of charges with different burning speeds in the simulator chamber, the charges are tested with the same round discharge port of critical section with pressure measurement in the chamber simulator, each charge is thermostated to a temperature that ensures the burning rate of the charge and pressure in the engine with minimal deviations from their nominal onal values and determined by the formula:

where t _term is the temperature of temperature control of the charge before the fire bench test (AIS);

t _max - maximum temperature in the operating range;

t _min - the minimum temperature in the range of operation;

- скорость горения заряда в конкретной партии, определенная в приборе постоянного давления (ППД); $$u_{PPD}^i$$

- the rate of combustion of a charge in a particular batch, determined in a constant pressure device (PPD);

u _max - the maximum burning rate of the charge at the maximum temperature in the operating range;

u _min - the minimum burning rate of the charge at the minimum temperature in the operating range.

The proposed method for confirming the VBH and SEC (as an example for a specific charge in the case of AID) is illustrated by diagrams.

" (горизонтальная ось), как иллюстрация предложенной в формуле математической зависимости $$t_{терм}\left(u_{ППД}^i\right)$$

. Точка пересечения с наклонной линией зависимости перпендикуляра от конкретного значения " $$u_{ППД}^i$$

" и определяет конкретную температуру $$t_{терм}^i$$

.In FIG. 1 shows a diagram t _term (vertical axis) from " $$u_{PPD}^i$$

"(horizontal axis), as an illustration of the mathematical dependence proposed in the formula $$t_{teRm}\left(u_{PPD}^i\right)$$

. The intersection point with the inclined line of the dependence of the perpendicular on a specific value " $$u_{PPD}^i$$

"and determines the specific temperature $$t_{teRm}^i$$

.

In FIG. 2 shows the nominal and limiting dependences of the pressure in the chamber p (τ) using a single supply opening with the same d _cr and thermostating by the proposed method.

In FIG. 3 shows the nominal and limiting dependences of the pressure in the chamber p (τ) with the same d _cr , but without the proposed temperature control.

The graph of FIG. 2 has a narrow pressure spread in the chamber p (τ) with a small spread in the total charge operating time (τ _p ) in comparison with the graphs of FIG. 3, where the limiting burning rate and the limiting temperature of the charge cause an out-of-order pressure in the chamber or an out-of-time operation of the engine, which can lead to a burnout of the thermal current loss chamber.

To implement the indicated method for confirming the VBH and SEC of a solid fuel charge, the bench device shown in FIG. 4, 5 and 6. In FIG. 4 shows a front view of the proposed bench device, in FIG. 5 shows a top view of a bench device, FIG. 6 is a side view of a bench device.

Conducted bench burning of solid solid fuel charges (with different burning rates) according to the proposed method for confirming the VBH and EC (with preliminary temperature control) are illustrated by diagrams (see Fig. 2), which confirm the limiting dependences p (τ) and the nominal dependence p ^nom (τ) .

The proposed method for confirming the VBH and SEC charge in the simulator chamber allows to reduce the number of components necessary for carrying out the AIS during charge development, as well as significantly reduce the scatter of the measured parameters, thereby increasing the reliability of the engine design as a whole.

To implement the proposed method for confirming the VBH and SEC solid propellant charge of a rocket engine, a bench device is used.

The proposed bench device uses the well-known principle of "Static rotation bench" to determine the thrust momentum of a special engine of the "Segner wheel" type (see, for example, the book "Experimental methods for determining the parameters of special-purpose engines", author IM Gladkov, BC Mukhamedov , E.L. Valuev, V.I. Cherepov, M. 1993, MIT).

The objective of the invention is to simplify the design of the bench device with the ability to use a power meter with a wide range of measurements for engines with different thrusts with one nozzle (for example, in the range of _thrust R = 1-50 kgf) while maintaining the required error in determining the dependence of R _thrust (τ).

The task was performed in a bench device containing a metal slipway with a horizontal rotary plate for attaching a simulator chamber with a round consumable critical hole, a pressure measuring sensor in the simulator chamber, a force meter between the rotary plate and the slipway, the slipway has a vertical contact wall to which it is attached bracket with bearing assembly for the vertical shaft of the turntable, the load meter is mounted on the vertical thrust wall of the slipway and is in contact with the side surface a rotary plate, which has vertical racks under the simulator chamber, in contact with the floor of the test bench through end bearings whose axes are parallel to the vertical contact wall of the slip, the rotary plate and the vertical contact wall of the slip are connected in a horizontal plane by a coiled spring for the initial compression of the rotary plate to the load cell , the simulator chamber is enclosed in a heat-insulating casing, the simulator chamber has a pipeline with a nozzle, the axis of which is parallel to the axis of the force meter, while the axis of the pipe the wires with the nozzle and the load meter are perpendicular to the vertical contact wall of the slipway, the distances from the axis of the vertical shaft of the turntable to the axis of the load meter "l" and to the axis of the pipe nozzle "L" are connected by the ratio:

where F _forces - load meter readings,

R _sop - reactive thrust of the nozzle of the camera simulator.

The bench device consists of a metal slipway (see Fig. 4), the vertical thrust wall 1 of which is mounted on the floor 2 of the test bench. The horizontal rotary plate 3 has a vertical shaft 4 in the bearing assembly 5, which is mounted on the vertical thrust wall 1 using the bracket 6 (see Fig. 5).

On the rotary plate 3 (in the opposite side to the vertical shaft 4) there is a camera-simulator 7 with a solid fuel charge and a squib 8 (initiator of ignition charge). A force meter 9 (primary transducer) is fixed on the vertical thrust wall 1 between the vertical shaft 4 and the camera-simulator 7, the axis of which is perpendicular to the surface of the vertical thrust wall 1 and the side surface of the contacting rotary plate 3 and is located at a certain distance “l” from the axis of the vertical shaft 4 (see Fig. 5).

The rotary plate 3 and the vertical thrust wall 1 in the horizontal plane are connected by a coil spring 10 (see Fig. 5) for the initial compression of the rotary plate 3 to the load meter 9 (with almost constant force during operation).

The imitation chamber 7 (see Fig. 5) has a pipe 11 ending with a nozzle 12 (the axis of the nozzle is parallel to the axis of the force meter 9 and is spaced from the axis of the vertical shaft 4 at a certain distance "L"). On the camera-simulator 7 through the pipe mounted sensor measuring pressure 13 in the combustion chamber. A thermally insulated tank 15 is connected to the camera-simulator 7 through the gas outlet 14, which simulates the initial free volume of the combustion chamber of a standard engine.

The rotary plate 3 (see Fig. 6) below (under the installed camera-simulator 7) has vertical racks 16 with end bearings 17 in contact with the floor 2 of the test bench, and the axis of the bearings parallel to the vertical thrust wall 1 of the slipway.

The imitation chamber 7 is surrounded by a heat-insulating casing 18.

The axis of the force meter 9 and the axis of the nozzle 12 are in the same horizontal plane to eliminate errors in the measurement of the thrust vector. The axis of the nozzle 12 is spaced from the axis of the vertical shaft 4 at a certain distance "L" (see Fig. 5), which is determined by the dimensions of the stand.

In accordance with the claimed method, the thermostatically charged charge in the simulator chamber is installed on the stove 3 before the fire bench test and its temperature is stored until the end of the AIS using a heat-insulating casing 18.

After actuation of the igniter 8 and ignition of the charge, the combustion products through the gas outlet 14 fill a thermally insulated container 15, which dampens a possible pressure surge in the combustion chamber during the ignition of the charge.

(где F_сил - показания силоизмерителя).The jet thrust force of the nozzle R _SOP 12 compresses the sensitive head of the primary transducer (force meter) 9 to the lateral vertical surface of the horizontal rotary plate 3. The distance "l" from the horizontal axis of the force meter 9 to the vertical axis of the shaft 4 is selected based on the conditions of the measuring range of the particular force meter. With a more "coarse" force meter (with an increased range of force measurement) it is installed closer to the axis of the shaft 4 and thereby precisely confirm the reactive force R _sop from the engine nozzle in accordance with the ratio

(where F _forces - load meter readings).

Using in the processing of the AXI results the mass of burnt fuel and the thrust integral J _Rсоп (τ) determine the practical specific charge impulse to confirm the energy characteristics of the engine and the charge characteristics of the products of charge combustion.

Fire tests on the proposed bench device allow the rational use of available power meters to determine the energy characteristics of the charge with a minimum error with a limited number of experiments.

Claims (4)

1. A method of confirming the ballistic and energy characteristics of the solid propellant charge of a rocket engine, which consists in burning a series of charges with different burning speeds in a simulator chamber with a round critical flow inlet with measuring pressure in a simulator chamber, characterized in that the charge is thermostated to a temperature before combustion providing the burning rate of the charge and pressure in the engine with minimal deviations from their nominal values and determined by the formula:

where t _term is the temperature of temperature control of the charge before the fire bench test (AIS);
t _max - maximum temperature in the operating range;
t _min - the minimum temperature in the range of operation;
$$u_{PPD}^i$$

^{_ the} rate of combustion of a charge in a particular batch, determined in a constant pressure device (PPD);
u _max - the maximum burning rate of the charge at the maximum temperature in the operating range;
u _min - the minimum burning rate of the charge at the minimum temperature in the operating range. 2. A bench device for confirming the ballistic and energy characteristics of the solid propellant charge of a rocket engine, containing a metal slipway with a horizontal rotary plate for mounting a simulator chamber with a round critical hole, a pressure measuring sensor in the simulator chamber, a force meter between the rotary plate and the slipway the fact that the slipway has a vertical thrust wall to which a bracket with a bearing assembly for the rotary vertical shaft is mounted plates, the load meter is mounted on the vertical contact wall of the slipway and is in contact with the side surface of the swing plate, the swing plate and the vertical contact wall of the slipway are connected in a horizontal plane by a coil spring for the initial compression of the rotation plate of the slipway to the load meter, the swing plate under the simulator camera has vertical racks in contact with the stand floor through end bearings, the axes of which are perpendicular to the axis of the load cell, the simulator chamber is enclosed in a heat-insulating casing, the chamber Tatorey has a conduit with a nozzle, which is parallel to the axis siloizmeritelej axis, the axis of the conduit with the nozzle and siloizmeritelej perpendicular vertical abutment wall of the pile, the distance from the axis of the vertical shaft of the rotary plate to siloizmeritelej axis "l" and to pipe nozzle axis "L" are related by:

where F _forces - load meter readings,
R _sop - reactive thrust of the nozzle of the camera simulator. 3. The device according to p. 2, characterized in that the axis of the load meter and the nozzle of the pipeline are in a common horizontal plane. 4. The device according to p. 2, characterized in that the simulator chamber is equipped with a thermally insulated tank that simulates the initial free volume of the combustion chamber of a standard engine.

Images