RU2415290C1 - Ignition device of sample of solid rocket propellant, and ignition method by using such device - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: ignition device of sample of solid rocket propellant includes housing in which there arranged is charge of priming composition, as well as flow holes. The latter are located in waveguide bushing. Housing and charge of priming composition is attached on the outside to the bushing by pressure nut and located on the outside around flow holes beyond high-temperature zone of measuring path of burning velocity of primary charge in bushing. Inside priming composition there located is heated metal wire of electric igniter. Ignition method of sample of solid rocket propellant by using the above device involves response of charge of priming composition. By means of heated metal wire of electric igniter, which is located inside charge of priming composition there performed is simultaneous ignition of the whole charge of priming composition in the area of flow holes. Then, combustion products of priming composition are supplied through flow holes to ignited surface of sample and ignition of the sample surface is performed. During the sample ignition there formed is stable zone in the area of ignited surface.

EFFECT: improving measurement accuracy of burning speed of solid rocket propellant sample.

3 cl, 4 dwg

Description

The invention relates to rocket technology, and more particularly to ignition devices (WU) of solid rocket fuels (TRT) and ignition methods for small model installations and bench tests.

A known method of starting a solid propellant rocket engine (RTTT) and an ignition device for its implementation (RF patent No. 2324067, publ. 10.05.2008), considered as the closest analogue of the invention.

WU includes a housing in which the charge is placed, and consumable openings preceding the consumable openings with channels of variable cross-section and the direction of the outflowing stream of combustion products of the charge.

The corresponding method includes the activation of the charge of the WU, the expiration of the combustion products through channels of variable cross-section and direction, then through the supply openings to the main chamber and ignition of the main charge.

A significant drawback of the device and method when they are used in the study of TRT samples by microwave methods for measuring the TRT burning rate is the presence in the high-temperature zone of the measuring path of the structural elements of the HF, from which reflections of the microwave electromagnetic wave arise, which reduces the accuracy of the measurement of the burning rate.

Also, the reversal of the flow of the products of combustion of the charge of the WU in the profiled channels of variable cross-section and direction leads to an increase in the residence time of the products of combustion in the body of the WU and, as a result, the cooling of the flow of products of combustion, which reduces the reliability of the guaranteed ignition of the main charge.

In addition, the disadvantage of the prototype is the technological complexity of large-scale reduction for small research model installations of its large WU with small profiled channels.

The tasks solved by the proposed device and method are:

- providing high-precision measurement of the speed of combustion TRT,

- ensuring reliable and uniform ignition and combustion of the TPT sample,

- simplifying the design and reducing the mass-dimensional characteristics of the WU.

The technical effect is achieved by the fact that the ignition device includes a housing in which a charge of the igniter composition (BC) is located, as well as consumable openings, wherein the consumable openings are located in the waveguide sleeve, and the housing and the charge of the aircraft are pressed externally to the sleeve by a compression nut and are located outside around the consumables holes and thus outside the high-temperature zone of the measuring path of the burning rate of the main charge in the sleeve, also inside the aircraft there is an incandescent metal wire of an electric igniter.

The radius of the supply openings in the sleeve is determined from the condition of hole criticality for the used radiation frequency in the measuring path according to the formula

,

,

where R _kr is the maximum radius of the supply openings necessary to ensure the conditions of criticality of the supply openings, ε is the relative dielectric constant, λ is the wavelength in the microwave path,

The number of supply openings is determined from the conditions of subsonic outflow of combustion products of the aircraft according to the formula

, где

where

,

,

,

,

- минимальная суммарная площадь расходных отверстий, необходимая для обеспечения дозвукового истечения продуктов сгорания,

- массовый газоприход от ВС, R - газовая постоянная продуктов сгорания ВС, Т - температура продуктов сгорания ВС, р_к - давление создаваемое воспламенителем, γ - показатель процесса расширения продуктов сгорания ВС.Where n is the required number of supply holes,

- the minimum total area of the supply openings necessary to ensure the subsonic flow of combustion products,

- mass gas intake from the aircraft, R - gas constant of the combustion products of the aircraft, T - temperature of the combustion products of the aircraft, p _to - pressure created by the igniter, γ - indicator of the expansion process of the combustion products of the aircraft.

The method of igniting a TPT sample includes triggering the charge of the aircraft, the expiration of its combustion products through the supply openings to the combustible surface of the sample and igniting the surface of the sample, using the proposed device in which the simultaneous ignition of the entire aircraft charge in the area of the supply openings provides an incandescent metal wire inside the charge BC, and when the sample is ignited, a stagnant zone is formed in the area of the flammable surface.

List of drawings

Figure 1 - WU gas torch type;

Figure 2, 3 - options for the location of incandescent wire in the sun;

Figure 4 - simulation results of the distribution of the burning rate of the sample TRT.

Indicated by continuous numbering of positions: 1 - aircraft; 2 - consumable holes; 3 - ignition surface of the TPT sample; 4 - waveguide sleeve; 5 - sample TRT; 6 - WU case; 7 - clamping nut; 8 - insulating sleeve; 9 - incandescent wire.

Figure 1 shows the design of the WU used in the proposed method of ignition of the sample TRT. The VU contains a waveguide sleeve (4), in which a TPT sample (5) is placed. The aircraft (1) is located in the housing (6) and is tightened by a nut (7). For insulation of a heated metal wire (9) of an electric igniter igniting an aircraft, insulating sleeves (8) are installed in the housing (6).

Significantly new is that, unlike the prototype, the small length of the cylindrical flow openings (2) of small heat transfer length in the sleeve (4) provides a correspondingly short residence time of the combustion products of the aircraft in contact with the housing (6), which reduces the loss of temperature of the combustion products on thermal conductivity and the formation of the stagnant zone of almost zero gas velocity in the region of the ignition surface (3) of the sample (Fig. 4, the lower edge of the gas motion simulation diagram obtained using software Aket ANSYS CFX) positively affects the uniformity and reliability of ignition of the sample. The diagram of the nature of the gas movement near the end-type combustion surface shows the formation of a stagnant gas zone at the ignition and combustion surface, which increases the uniformity of ignition and combustion and ensures that there is no possibility of erosive combustion of the TPT sample.

In addition, the ignition of the aircraft (1) is provided not by a locally standard pyroelectric gun igniter, but by an incandescent metal wire of sufficient length, which gives simultaneous ignition of the entire aircraft and uniform consumption of its combustion products through all the supply openings. Also, the design of the VU does not have any elements in the high-temperature zone of the measuring path of the sample burning rate, from which reflections of the microwave electromagnetic wave could arise, which would lead to a decrease in the accuracy of measuring the burning speed of the TRT sample.

In the waveguide sleeve (4), axisymmetric radial flow openings (2) are located, directed at an angle to the ignition surface (3) of the TPT sample.

Example of calculating the radius and number of supply holes

The relative dielectric constant of air is ε = 1.

The wavelength in the microwave path is λ = 0.033 m.

from technological considerations, choose R _cr = 1 mm.

The exponent of the expansion process is γ = 1.39.

.Gas constant

.

The temperature of the combustion products T = 2800 K.

The pressure generated by the igniter p _k = 2 MPa.

.Mass gas inlet from aircraft

.

,

,

,

,

.

.

Rounding to the nearest larger integer, we take the number of holes n = 10.

The method of ignition of the TPT sample using the proposed WU is implemented as follows.

Ignition of the aircraft is carried out by electric heating of a metal wire located in the bulk of the aircraft. The combustion products of the aircraft, passing through the supply openings, are sent to the flammable end face of the TRT sample. The result is a uniform flow of combustion products through the supply openings, which contributes to reliable ignition of the TPT sample.

And the placement of the design elements of the VU outside the high-temperature zone of the measuring path significantly increases the accuracy of measuring the burning rate of the sample with small mass and size characteristics of the device.

Claims (3)

1. A device for igniting a sample of solid rocket fuel, comprising a housing in which a charge of igniter composition (BC) is located, as well as consumable holes, characterized in that the consumable openings are located in the waveguide sleeve, and the body and charge of the aircraft are docked with a compression nut from the outside and located outside around the supply openings and thus outside the high-temperature zone of the measuring path of the burning rate of the main charge in the sleeve, also inside the aircraft there is a heated metal wire electric drip. 2. The device according to claim 1, characterized in that the radius of the supply holes in the sleeve is determined from the condition of criticality of the holes for the used radiation frequency in the measuring path according to the formula:

,
where R _kr is the maximum radius of the supply openings necessary to ensure the conditions of criticality of the supply openings, ε is the relative permittivity, λ is the wavelength in the microwave path;
and the number of supply openings is determined from the conditions of subsonic outflow of combustion products of the aircraft according to the formula:

Where

n is the required number of consumable holes,

- the minimum total area of the supply openings necessary to ensure the subsonic flow of combustion products,

is the mass gas inlet from the aircraft, R is the gas constant of the combustion products of the aircraft, T is the temperature of the combustion products of the aircraft, p _to is the pressure created by the igniter, γ is an indicator of the expansion process of the combustion products of the aircraft. 3. The method of ignition of the TPT sample, including the actuation of the charge of the aircraft, the expiration of the products of its combustion through the supply openings to the combustible surface of the sample, the ignition of the surface of the sample, characterized in that the device for ignition of the TPT sample according to claim 1 or 2, the simultaneous ignition of the entire charge of the aircraft in the area of the supply openings is provided with an incandescent metal wire with an electric spark inside the aircraft charge and, when the sample is ignited, a stagnant zone is formed in the area of the combustible surface.

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