RU2406863C1 - Method of multiple laser ignition of rocket fuel mixtures and device for its implementation - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention can be used for multiple start-up of rocket engines (RE) operating both on liquid and on gaseous fuel mixtures in conditions of their operation on rockets, space vehicles and orbital manned space stations, as well as at bench adjustments of engines. Device for multiple laser ignition of fuel mixture in rocket engines includes laser radiation source, at least one light guide connected through the radiation introduction system to laser radiation source; at that, outlet edge of light guide is made so that it absorbs energy from the above laser radiation source; and mechanism of supply at least of one light diode for repeated ignition of fuel mixture in combustion chamber of rocket engine.

EFFECT: improving reliability of ignition, its simplification and cheapening.

4 cl, 1 dwg

Description

The present invention relates to the field of rocket and space technology and can be used for multiple launch of rocket engines (RD) operating both on liquid and gaseous fuel mixtures under conditions of their operation on rockets, spacecraft and orbital manned space stations, as well as testing engines in bench conditions.

The prior art "Method of ignition of the fuel mixture" according to SU No. 1778842, 11/30/1992 g. The invention according to SU No. 1778842 consists in the fact that the chamber of the spark plug of the fuel mixture in ICE running on light fuel is filled with the charge of the fuel mixture, create spark plugs in two stages on spark plug electrodes. At the first stage, a high-voltage short pulse is supplied and a breakdown of the interelectrode gap is provided; at the second stage, a low-voltage high-current pulse is supplied and the fuel mixture is ignited in the candle chamber. As a result, the fuel mixture in the combustion chamber of the engine will ignite from the flow of hot gases, collectively generated from the energy of combustion of the fuel mixture in the spark chamber and the energy of the high-current discharge between the electrodes of the spark plug.

The disadvantage of this method is that it cannot provide reliable ignition of rocket fuel mixtures due to the low voltage of the generated electric discharge and the small volume of the fuel mixture burned in the chamber of the candle.

The prior art also known a method of ignition of a charge by controlled electromagnetic radiation according to US patent No. 3601054, F41A 19/63, F42B 05/08, F42C 19/12, publ. 1971, which consists in the fact that the first part of the propellant charge (igniter or fuse) is placed at the bottom of the flammable charge, in the center of which metal initiators are placed, which, when fired, are irradiated with electromagnetic radiation in the microwave range, for example, at a frequency of 13 GHz, heating metal initiators (conductors of the same length corresponding to half the wavelength of electromagnetic radiation) to the ignition temperature of the first part of the propellant charge (igniter), which then ignites in turn the second (main th) part of the propellant

Also known is a device for igniting a charge by heating its elements with a laser beam (see, for example, patents: US No. 4870903; Japan No. 2000055594; Japan No.2001082900; France No. 2679640). Such a device contains a laser, the beam of which is directed to the end igniter located in the bottom of the flammable charge through a window in the shutter with a complex optical system that provides radiation energy distribution along the length of the axial igniter charge device, or such distribution is made by dividing devices in charge, which naturally complicates its construction. In this case, the localization of the ignition of the charge takes place, as in the case of ignition devices of the charge, for example, the traditional capsule type, with a multi-stage principle of operation. This device has low reliability due to the high probability of a quick failure when firing an optical system.

In the method according to the patent RU 2326263, ignition is carried out by focusing the laser energy into the region of optical breakdown at a time when the ratio of the fuel components in this region is optimal for ignition.

The method of ignition of the fuel mixture in the combustion chamber of an engine according to patent RU 2339840 is based on filling the spark chamber with fuel in the composition of the fuel and oxidizer and its ignition using an auxiliary energy source, while the fuel and oxidizer are supplied to the spark chamber separately, and use as an auxiliary energy source a pulsed laser whose energy is focused on the fuel mixture in the volume of the candle chamber, where a volumetric electric discharge is created in the reaction zone and the fuel mixture is ignited, from which d is formed in the combustion process of the spark plasma torch chamber in the engine combustion chamber and fuel mixture is ignited it into the engine combustion chamber. To ignite the fuel mixture with a laser spark (optical breakdown), a laser is required, the parameters of which are determined by the breakdown thresholds of the laser mixture.

In the mentioned patents, it is proposed to use an optical breakdown to ignite the combustible mixture, which is created by laser radiation in the volume filled with the fuel mixture, for the initiation of which it is necessary to use a pulsed laser with a very high output radiation intensity. At present, solid-state lasers, as a rule, with an active medium of Nd: YAG (neodymium garnet), including a system for producing short pulses, have the best and most suitable characteristics for these purposes, which significantly complicates the device for laser ignition as a whole.

Another significant drawback of the above methods is that when laser firing of fuel mixtures based on optical breakdown on optical elements that emit radiation into the combustion chamber, soot settles, which makes it impossible to re-ignite the fuel of rocket engines without cleaning these elements.

The present invention aims to eliminate the above disadvantages and to create such a laser ignition device, which makes it possible to implement multiple ignition of fuel in rocket engines, and also significantly increases reliability, simplifies and reduces the cost of ignition.

Figure 1 shows a diagram of an embodiment of the invention, where 1 is a combustion chamber, 2 are nozzles for injecting fuel and an oxidizing agent into a combustion chamber, 3 is a combustion torch of a fiber, 4 is a mechanism for supplying a fiber to a combustion chamber, 5 is a fiber, 6 is a system radiation input into the fiber and 7 - laser (matrix of laser diodes).

The principle of operation of the proposed device is as follows. Laser radiation from a source (pos. 7) of laser radiation is directed through a radiation input system (e.g., a lens) (pos. 6) into a light guide (pos. 5), in which the output end is coated with a light-absorbing material or specially processed (for example, fused) in such a way so that laser radiation from the source (pos. 7) is absorbed in the plane of the output end of the fiber.

For a more confident start, you can use several optical fibers (pos. 1) located in the combustion chamber (pos. 1) in any configuration (not shown).

At the same time, the location of the hole in the combustion chamber (pos. 1) for introducing the fiber into it (pos. 5) is located near the nozzles of the combustion chamber (pos. 1), where the gas flow rate is small and the fiber (pos. 5) can be inserted into the combustion chamber (item 1) without an additional holder for the optical fiber (for example, a tube). In the combustion chamber is only the final section of the fiber of small length, which is determined by the combustion conditions.

The laser radiation absorbed in the output end heats the end of the fiber located in the combustion chamber to high temperatures, which can reach the melting or boiling points of the fiber material (about 1500-2000 ° C).

There are two options for firing fuel:

1) The ignition of the fuel occurs upon contact with the highly heated output end of the fiber, while the fiber itself does not burn.

2) The output end of the fiber begins to burn itself, while spraying hot particles of its substance (quartz) and the metal casing surrounding the fiber (item 3).

The implementation of one of these possible ignition options depends on the ignition temperature of the fuel under given conditions in the combustion chamber (temperature, pressure, medium velocity, etc.). The implementation of the first option requires significantly lower laser radiation power than for the second. With the proper power of the supplied laser radiation, the combustion will be intense, able to set fire to any combustible mixture.

To increase the combustion temperature, a special mixture can be applied to the surface of the fiber (pos. 5) (both in a continuous layer and through gaps equal or different in length), for example, termite. When ignited, such a mixture burns out intensively with the release of a large amount of heat, which increases the temperature in the ignition area and contributes to the ignition of the fuel mixture.

Laser radiation is fed into the optical fiber during the entire time of ignition of the fuel, until its stable combustion is achieved.

In order to carry out the next ignition, the end part of the fiber burnt during the previous ignition is compensated by introducing a new section of the fiber into the combustion chamber by means of the fiber supply mechanism (pos. 4), and its end will already be melted. The fiber supply mechanism is a rotational drum, on which a fiber is wound, having the required length margin. One end of the fiber is rigidly connected to the radiation input system, the other is output to the combustion chamber and fixed in the outlet in the wall of the combustion chamber. When the feed mechanism is turned on, the fixation is released, the drum is rotated (for example, by a stepper electric motor or a spring mechanism) to the required angle so as to extend the output end of the fiber into the combustion chamber to the desired length. The supply of the fiber to the combustion chamber can also be carried out during the ignition process. Regardless of the current state of engine operation, the end section of the fiber is always located in the combustion chamber, which completely covers the hole in the wall of the combustion chamber through which the fiber is supplied, isolating the rest of the fiber from the combustion chamber.

Ignition of rocket engines is as follows. Through a hole in the wall of the chamber (pos. 1) of the combustion, a fiber (pos. 5) extends to a certain depth either without support or using some holder (not shown). In the fiber (pos. 5) from the source (pos. 7) laser radiation is supplied, pulsed or continuous. The output end of the fiber, which absorbs the radiation supplied to the fiber, heats up strongly and ignites the fuel mixture in the combustion chamber (item 1). In this case, the terminal portion of the fiber located in the combustion chamber can also burn. The remaining output end of the fiber will have an end face melted and coated with products of combustion (soot), i.e. still remain well absorbing radiation. In this case, the rest of the fiber (pos. 5), which remains isolated behind the wall of the combustion chamber (pos. 1), will remain intact and ready for operation. To restart the rocket engine (ignition of fuel), it will only be necessary to extend the optical fiber again into the combustion chamber (item 1) and apply laser radiation from the source (item 7).

It is supposed to use a laser diode assembly (laser diode array) operating in a continuous mode as a source (pos. 7) of laser radiation. This mode warms up the end of the fiber faster and does not require complex pumping systems and power supplies - you can use aircraft batteries. It is sufficient to make the cooling of the laser diode matrix passive (conductive heat sink to a copper or aluminum bar), since the time of heating the end of the fiber and igniting the fuel mixture occurs in a short period of time, during which the matrix does not have time to overheat.

When using a diode laser (laser diode array), the system will be very simple, reliable and economical.

Claims (4)

1. A method of reusable laser ignition of fuel mixtures in rocket engines, comprising the following steps: at least one optical fiber is inserted into the combustion chamber of rocket engines, which is connected at one end to a laser source, and at the other end located in the combustion chamber of a rocket engine, radiation from said laser source is absorbed; said at least one light guide is supplied with energy from a laser source; in order to re-ignite by means of the fiber supply mechanism, said at least one optical fiber is re-introduced into said combustion chamber and energy is supplied from said laser radiation source. 2. A device for reusable laser ignition of fuel mixtures in rocket engines, containing a laser source, at least one optical fiber connected through a radiation input system to a laser radiation source, while the output end of the optical fiber is absorbing energy from said laser radiation source; and a feed mechanism for at least one fiber for re-ignition of the fuel mixture in the combustion chamber of the rocket engine. 3. The device according to claim 2, characterized in that in it the source of laser radiation is a matrix of laser diodes. 4. The device according to claim 2, characterized in that in it the surface of said at least one fiber is coated with a thermite mixture.