JP3559867B2 - Combustion device for ramjet engine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a combustion device for a ramjet engine and a combustion control method thereof. More specifically, the present invention relates to a ramjet engine combustion device that stably maintains flame at a wide flight Mach number, has high combustion efficiency, and emits a small amount of nitrogen oxides, and a combustion control method therefor.
[0002]
[Prior art]
In order to increase the transport capacity of jet airliners, supersonic airliners that fly at an altitude of 25,000 m at a cruising speed of a flight Mach number of about 5 have been developed. As the engine of this supersonic airliner, where the speed exceeds the flight Mach number 2.5, sufficient compression pressure can be obtained only by using the ram pressure, the use of a ramjet engine has been studied. I have.
[0003]
The ramjet engine is currently used for missiles and unmanned target aircraft. However, since they are mainly used for military purposes, the combustion efficiency is low at the low equivalent ratio of off-design, and furthermore, since they do not have means for suppressing pollutant emission, especially nitrogen oxide emission, At rated output, very high levels of nitrogen oxide emissions are produced. Therefore, a conventional ramjet engine cannot be used as it is as an engine of a supersonic airliner flying at an altitude where air pollution such as destruction of the ozone layer is an important problem.
[0004]
For the purpose of solving the problems of the currently used ramjet engine and providing a ramjet engine having a low-pollution combustion furnace, Japanese Patent Application Laid-Open No. Hei 5-187321 discloses a ramjet engine.
a) fuel atomization means are provided in a plurality of injection modules arranged in the gas flow channel and equally spaced in a plane perpendicular to the path of the gas;
b) said modules each comprising a cover diverging in the direction of gas flow and having an inlet orifice for the first combustion aid stream upstream thereof, forming a space between said covers for the circulation of the second combustion aid stream; Are arranged so that
c) fuel atomization means injects fuel into the first co-fuel flow such that a very concentrated mixture undergoing the first combustion is formed in the volume defined by the cover;
d) the cover rapidly dilutes gas from a first combustion in a second co-firent stream near an outlet of the cover so as to form a burned lean mixture downstream of the module. A ramjet engine is proposed, characterized in that each injection module has a means for propagating a flame toward a nearby module and a means for thermal protection of the gas flow wall. And a ramjet engine comprising a gas flow wall cooling means.
[0005]
However, in the ramjet engine according to the above proposal, another problem is that the structure of the module constituting the main part is complicated, so that the structure is complicated, resulting in an increase in manufacturing cost and process. There is a problem.
[0006]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the problems of the prior art, and has a simple combustion used in a ramjet engine having good combustion efficiency in a wide flight Mach number range and reduced nitrogen oxide emission. It is an object of the present invention to provide a combustion device having a configuration and a combustion control method therefor.
[0007]
[Means for Solving the Problems]
The combustion device for a ramjet engine according to the present invention includes at least an inner combustion device and an outer combustion device, wherein the inner combustion device and the outer combustion device are separated by an inner liner, and the inner liner has a gas at a rear end. Having a mixing means, the inner combustion device has a fuel injector near the front end of a space formed by the inner liner and a flame stabilizer arranged at a predetermined position behind the fuel injector, The outer combustion device has a fuel injection section in a space formed by the inner liner and the combustion duct near the gas mixing means .
[0008]
In the combustion device for a ramjet engine according to the present invention, the gas mixing means is a mixer having a corrugated plate in which an outer envelope surface is formed in a divergent nozzle shape and an inner envelope surface is formed in a convergent nozzle shape. the preferred there to have.
[0011]
[Action]
In the present invention, the combustion device includes at least an inner combustion device and an outer combustion device. Therefore, at low flight Mach number, combustion is performed only by the inner combustion device, so that combustion can be performed at a stoichiometric mixture ratio or a mixture ratio close to the stoichiometric ratio even though the absolute amount of fuel is small, and the combustion reaction time is also reduced. Can be longer. Therefore, combustion is stabilized. Further, at the time of high flight Mach number, combustion is performed by the inner combustion device and the outer combustion device, so that lean mixed combustion can be performed despite the increase in the absolute amount of fuel, and the generation of nitrogen oxides can be suppressed. .
[0012]
In a preferred embodiment of the present invention, the temperature distribution of the exhaust gas from the ramjet engine is made uniform because the inner combustion device has gas mixing means at the end of the combustion gas discharge with the gas from the outer combustion device. You. Therefore, exhaust noise caused by variation in the exhaust gas temperature distribution is reduced.
[0013]
Further, in another preferred aspect of the present invention, the convection time of the combustion gas is shortened because the fuel injection section of the outer combustion device is disposed near the gas mixing means. Therefore, generation of nitrogen oxides is further suppressed.
[0014]
【Example】
Hereinafter, the present invention will be described based on embodiments with reference to the accompanying drawings, but the present invention is not limited to only the embodiments.
[0015]
One embodiment of a combustion device for a ramjet engine (hereinafter simply referred to as a combustion device) according to the present invention is shown in FIG. 1, and the combustion device A includes an inner combustion device 1 and an outer combustion device 2 as main components. . The inner combustion device 1 and the outer combustion device 2 are separated from each other by an inner liner 11 constituting the inner combustion device 1. Therefore, the air passage and the flue gas passage of the inner combustion device 1 and the outer combustion device 2 are independent of each other. Here, the design point of the inner combustion device is that the flight Mach number is about 3, the mixing ratio of fuel and air at that time is about 1.0, and the design point of the outer combustion device is the flight Mach number. Is about 5, and the mixing ratio of fuel and air at that time is about 0.4.
[0016]
In this case, when only the inner combustion device 1 is activated, the exhaust gas from the inner combustion device 1 and the air that has just passed through the outer combustion device 2 have a temperature difference. In this embodiment, a mixer that forms the gas mixing means 12 is provided at the rear end of the inner liner 11 of the inner combustion device 1 because a so-called jet noise is generated due to the difference between the two. For example, as shown in FIGS. 2 and 3, the mixer 12 has a corrugated plate whose outer envelope surface 12a is formed in a divergent nozzle shape and whose inner envelope surface 12b is formed in a convergent nozzle shape. Used. However, it is not limited to this.
[0017]
The inner combustion device 2 has a fuel injection unit 14 and a flame stabilizer 15 inside a space 13 formed by the inner liner 11. The fuel injection section 14 is provided near the front end of the inner liner 11, and the flame stabilizer 15 is arranged at a predetermined position behind the fuel injection section 14 in a predetermined arrangement. Here, the fuel injection unit 14 is configured by, for example, a ring-shaped fuel injection pipe or a rod-shaped fuel injection pipe in which a large number of fuel injection holes 14a are formed toward the downstream side. The size and number of the fuel injection holes 14a formed in this fuel injection pipe are appropriately adjusted according to the desired output. For example, in the case of a ring-shaped injection pipe, the diameter is 1 mm, the pitch is 10 mm, and the number is 82. Is done. As the flame stabilizer 15, for example, a V-gutter flame stabilizer is used. For example, when a ring-shaped fuel injection tube is used, the shape of the flame stabilizer 15 is formed in a ring shape corresponding thereto, and when a rod-shaped fuel injection tube is used, the shape thereof is formed in a shelf shape corresponding thereto. You.
[0018]
The outer combustion device 2 has a fuel injection unit 22 inside a space 21 formed by the inner liner 11 and the combustion duct 3 provided outside the inner liner 11. As the residence time of the combustion gas becomes longer, as shown in FIG. 4, the rate of generation of nitrogen oxides increases. Therefore, the fuel injection section 22 is arranged near the mixer 12. The fuel injection section 22 is also formed of a ring-shaped or rod-shaped fuel injection pipe, like the fuel injection section 14 of the inner combustion device 1. The size and number of the fuel injection holes 22a of the fuel injection tube are also appropriately selected according to the desired output. For example, in the case of a rod-shaped fuel injection tube, a rod-shaped fuel injection tube having a hole diameter of 1 mm and six injection holes is provided. Are arranged uniformly on the circumference of the combustor.
[0019]
Next, combustion in the combustion device for a ramjet engine configured as described above will be described with reference to FIGS.
[0020]
(1) Pilot fuel is injected from a pilot fuel injection nozzle (not shown) provided in the flame stabilizer 15.
[0021]
(2) The pilot fuel is ignited by an ignition plug (not shown) to form a spark.
[0022]
{Circle over (3)} When the fire is stabilized, fuel injection from the fuel injection section of the inner combustion device 2 is started (see FIG. 5).
[0023]
{Circle over (4)} When the fuel supply amount from the fuel injection unit 14 of the inner combustion device 1 is increased and the flight Mach number reaches about 4, the supply of fuel from the fuel injection unit 22 of the outer combustion device 2 is also started. .
[0024]
(5) The fuel supply amount from the fuel injection unit 22 of the outer combustion device 2 is increased, while the fuel supply amount from the fuel injection unit 14 of the inner combustion device 2 is reduced (see FIG. 6).
[0025]
{Circle around (6)} At a high flight Mach number (design cruise point), the fuel amount injected from the fuel injection section 22 of the outer combustion apparatus 2 and the fuel injection section 14 of the inner combustion apparatus 1 has a mixing ratio in each combustion apparatus. , Are controlled to be substantially the same.
[0026]
【The invention's effect】
As described above, according to the ramjet engine combustion device of the present invention, the ramjet engine is configured by at least two combustion devices having independent gas flow paths. And at low flight Mach numbers, the fuel can be burned at the stoichiometric mixture ratio or a mixture ratio close to the stoichiometric mixture ratio by operating only the inner combustion device. Therefore, efficient combustion is performed even at a low flight Mach number where the absolute amount of fuel is small. In addition, at high flight Mach number, while the combustion amount in the outer combustion device is increased by the inner combustion device, the combustion amount in the inner combustion device is reduced from that at low flight Mach number, so An excellent effect that mixed combustion can be suppressed to suppress generation of nitrogen oxides can be obtained. Further, since the exhaust gas from the inner combustion device and the exhaust gas from the outer combustion device are mixed and exhausted by the gas mixing means, an effect that the temperature of the exhaust gas is made uniform and jet noise is reduced can be obtained.
[0027]
According to a preferred aspect of the present invention in which the fuel injection section of the outer combustion device is disposed near the gas mixing means, the residence time of the combustion gas can be shortened, and the generation of nitrogen oxides can be further suppressed. The effect is also obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a combustion device for a ramjet engine according to the present invention.
FIG. 2 is an end view of the mixer.
FIG. 3 is a longitudinal sectional view of the mixer.
FIG. 4 is a graph showing a residence time and a NO generation ratio.
FIG. 5 is an explanatory diagram of a state in which only the inner combustion device is activated at a low flight Mach number.
FIG. 6 is an explanatory diagram of a state in which an inner combustion device and an outer combustion device are activated at a high flight Mach number.
[Explanation of symbols]
1 inner combustion device 11 inner liner 12 gas mixing means (mixer)
13 Space formed by inner liner 14 Fuel injection unit 15 Flame holder 2 Outer combustion device 21 Space formed by inner liner and combustion duct 22 Fuel injection unit 3 Combustion duct A Combustion device for ramjet engine

Claims (2)

Comprising at least an inner combustion device and an outer combustion device,
The inner combustion device and the outer combustion device are separated by an inner liner,
The inner liner has a gas mixing means at a rear end,
The inner combustion device has a fuel injector near a front end of a space formed by the inner liner and a flame stabilizer arranged at a predetermined position behind the fuel injector.
The combustion device for a ramjet engine , wherein the outer combustion device has a fuel injection unit in a space formed by the inner liner and a combustion duct near the gas mixing unit . 2. The ramjet according to claim 1 , wherein the gas mixing means is a mixer having a corrugated plate having an outer envelope formed in a divergent nozzle shape and an inner envelope surface formed in a convergent nozzle shape. Engine combustion device.

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