JP3109780B2 - Pilot burner - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot burner used for ignition start of a combustor and flame holding in a ramjet engine mainly using liquid fuel.

[0002]

2. Description of the Related Art As is well known, a ramjet engine is
Propulsion is generated effectively in the supersonic range of 1.5 Mach or higher. For this reason, the ramjet engine starts and accelerates with a booster engine such as a rocket, and starts operating when the boost flight ends.

In a ramjet engine using a solid propellant as a booster, an IRR (Integral Rocket) in which the solid propellant is loaded in a combustor is provided.
In such a ramjet engine, a cover is provided at an air inlet of a diffuser, a port cover is provided at an opening of the diffuser to a combustor, and a rocket nozzle is provided inside a jet nozzle. It has a configuration provided.

In the above-described IRR type ramjet engine, after the solid propellant has been burned, the rocket nozzle is detached after the cover of the air intake and the port cover are removed, and the inside of the combustor has the atmospheric pressure. If the conditions such as the equivalence ratio of the mixed fuel, the air flow state in the combustor, and the flame of the igniter are prepared in a state where the pressure is about twice, the ignition of the combustor can be started.

[0005] In the ramjet engine as described above, factors that make it difficult to start ignition when shifting to ramjet operation include (a) a large air flow velocity in the combustor and (b) combustion. The air temperature inside the vessel is low,
(C) The static pressure of the air in the combustor is low.

Further, in the above-described ramjet engine, when each cover and the rocket nozzle come off, the pressure in the combustor, which had been high until then, rapidly decreases and becomes close to the external atmospheric pressure within a few seconds. In the course of such a pressure change in the combustor, the pressure range in which the engine can be started is extremely short, that is, several tens of milliseconds. Since the pressure change in the combustor and the passage of time substantially match, it is possible to predict the time to reach the upper limit pressure and the lower limit pressure of the above pressure range.

Therefore, in the above-described ramjet engine, after completion of the combustion of the solid propellant, each cover and the rocket nozzle are removed until the upper limit pressure of the startable pressure range is reached, and the timing of fuel injection and ignition by the igniter is adjusted as described above. The pressure range was adjusted.

Such a ramjet engine is described, for example, in "Encyclopedia of Missile Engineering", pages 140 to 146, published by Hara Shobo in 1990.

[0009]

However, in the above-described conventional ramjet engine, in the case of operating conditions such as starting at a high altitude and a large angle of attack, for example, the environment and the force acting on the ramjet engine are reduced. Due to the influence, the pressure change in the combustor may become more remarkable, and the time corresponding to the above pressure range may be further shortened, and it may be difficult to start the normal ramjet operation.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional situation, and has been made to increase the temperature in a combustor at the time of transition to ramjet operation, thereby increasing the air flow rate and static pressure in the combustor. It is an object of the present invention to provide a pilot burner for a ramjet engine that can change combustion temperature and improve combustion reactivity, and can realize reliable ignition start and continuous combustion.

[0011]

SUMMARY OF THE INVENTION A pilot burner according to the present invention is a pilot burner for a ramjet engine. An outer cylinder for forming a combustion space is mounted in a state in which an outlet on the end side is opened in a combustor of a ramjet engine, and a front end is curved at a position near the inlet in the outer cylinder. A bluff body is provided, an annular flow path is formed between the outer cylinder and the bluff body, and a blade having a twist angle with respect to the axis of the outer cylinder is provided in the annular flow path in a circumferential direction of the annular flow path. Are provided at predetermined intervals, and at the rear end of the bluff body, a pilot fuel injection nozzle is provided, and the outer cylinder is provided with:
An igniter for injecting a flame toward a combustion space at a rear end side of the bluff body is provided.
At the rear end of the bluff body, a catalyst for contactly burning a mixed flow of pilot fuel and introduced air is provided, and the outer cylinder is provided with an oxygen injection nozzle directed toward a combustion space on the rear end side of the bluff body. The configurations are provided, and these configurations are used as means for solving the problem.

[0012]

In the pilot burner according to the first aspect of the present invention, the air introduced from the inflow port is decelerated in the annular flow path between the outer cylinder and the bluff body, and is swirled by the blade provided in the annular flow path. And a recirculation flow is generated in the combustion space on the rear end side of the bluff body. And
Pilot fuel is injected from the injection nozzle at the rear end of the bluff body into the recirculation basin in the combustion space and diffused, and a mixture of introduced air and pilot fuel is continuously burned by ignition with an igniter, and the combustion is performed. Gas is injected from the outlet.

[0013] Thus, the pilot burner heats the air introduced into the combustor of the ramjet engine with the high-temperature combustion gas injected from the outlet, and further combustible mixes the introduced air with the main fuel in the combustor. It is a fire source for the chi.

[0014] In the pilot burner according to the second aspect of the present invention, the catalyst provided at the rear end of the bluff body stabilizes the continuous combustion in the recirculation flow region more reliably. By providing an oxygen injection nozzle toward the combustion space on the rear end side, oxygen is supplied at the time of ignition by the igniter when the air temperature is extremely low, and the dilution of combustion gas by nitrogen in low-temperature air is prevented. Try to keep the temperature of the combustion gas high.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pilot burner according to the first and second aspects of the present invention will be described below.

The pilot burner B of this embodiment is similar to that of FIG.
Is attached to the ramjet engine R as shown in FIG.
The ramjet engine R includes a fuel tank 52 filled with liquid main fuel, a combustor 53, and a jet nozzle 54 from the side of the head, and a plurality of diffusers 50 communicating with the inside of the combustor 53 on the side. Further, the diffuser 50 is provided on the lamp portion 51 of the diffuser 50.
A diagonal bypass 55 communicating from the vicinity of the air intake into the combustor 53 is provided, and a pilot burner B is mounted in the bypass 55.

The pilot burner B has a state in which the inflow port 1 at one end is directed toward the air introduction side of the ramjet engine R and the outflow port 2 at the other end is opened into the combustor 53 in the bypass 55. And an outer cylinder 3 for forming a combustion space. The outer cylinder 3 is configured such that its diameter increases in the direction of air flow from the inlet 1 to the main body and decreases in diameter from the main body to the outlet 2. The area ratio between the inflow port 1 and the outflow port 2 is set in consideration of the flow rate matching between the inflow air and the outflow gas.

Inside the outer cylinder 3, a bluff body 4 having a hemispherical front end and a flat rear end perpendicular to the axis is provided near the inflow port 1 thereof. Outer cylinder 3
The rear end side is a combustion space 5 and an annular flow path 6 is formed between the bluff body 4 and the outer cylinder 3.

A plurality of blades 7 having a twist angle with respect to the axis of the outer cylinder 3 are provided at the rear end of the annular flow path 6.
Are provided at predetermined intervals in the circumferential direction of the annular flow path 6 and in the same direction. In addition, the blade 7 of this embodiment
Has a smoothly curved shape.

At the rear end of the bluff body 4, a pilot fuel injection nozzle 8 is provided at the center, and a flame holding catalyst 9 made of a platinum net is provided therearound. The pilot fuel injection nozzle 8 communicates with a pilot fuel supply source 11 composed of a tank, a valve device, and the like via a fuel flow path 10 formed in the bluff body 4.

Further, the outer cylinder 3 is provided with an igniter 12 for injecting a flame toward the combustion space 5 and a nozzle 13 for injecting oxygen toward the combustion space 5. The igniter 12 is loaded with a suitable igniter so as to be able to inject a high-temperature, large-heat flame for several seconds, and is connected to an electrically operated ignition device 14. The oxygen injection nozzle 13 communicates with an oxygen supply source 15 including a tank, a valve device, and the like.

Here, the ram rocket engine R is
For example, as shown in FIG. 2, it is operated as an IRR type ram rocket engine. In this case, the solid propellant 56 is loaded into the combustor 53, the air intake of the diffuser 50 is closed with the cover 57, and the opening of the diffuser 50 and the opening of the bypass 55 with respect to the inside of the combustor 53 are connected to a common port. A rocket nozzle 59 is mounted on the inside of the jet nozzle 54, closed by a cover 58.

I equipped with the pilot burner B having the above configuration
The RR type ramjet engine R is a solid propellant 56
The vehicle starts and accelerates by igniting the solid propellant 56
When a predetermined speed is reached upon completion of the combustion, the rocket nozzle 59 is detached following the removal of the covers 57 and 58 (the state shown in FIG. 1). As a result, air flows into the diffuser 50 and the outer cylinder 3 of the pilot burner 1.

In the pilot burner B, the air introduced from the inlet 1 is decelerated (for example, about 10 m / s) in the annular flow path 6 between the outer cylinder 3 and the bluff body 4 and the air flow is reduced. A plurality of blades 7 are provided to generate a swirling flow, and a recirculating flow is generated in the combustion space 5 on the rear end side of the bluff body 4 as shown by an arrow in FIG. On the other hand, the air introduced into the diffuser 50 is decelerated and compressed and sent to the combustor 53.

Further, the pilot burner B ignites the igniter 12, thereby injecting a flame into a recirculation flow region generated in the combustion space 5, and an injection nozzle at the rear end of the bluff body toward the recirculation flow region. Pilot fuel is injected from 8.

At this time, the controller (not shown) calculates the air flow rate in the diffuser 50 based on the area of the reference inspection surface in the diffuser 50, the dynamic pressure, the static pressure, and the total air temperature, and calculates the air intake of the diffuser 50 and the pilot. The flow rate of air flowing into the pilot burner 1 is calculated from the area ratio of the burner B to the inflow port 1 and the flow coefficient which is experimentally obtained in advance, and the pilot fuel having a stoichiometric mixture ratio with respect to the air flow rate is calculated. Is calculated.

The pilot fuel supply system is independently controlled so as to always supply the pilot fuel at the calculated flow rate. Based on this, the pilot fuel supply source 1 is controlled.
In order to sufficiently increase the temperature of the combustion gas injected from the pilot burner 1, the fuel equivalent ratio in the outer cylinder 3 is φ =
The pilot fuel is supplied so as to be 1.

Thus, the pilot burner B
Then, the swirling flow generated by the blades 7 is converted into a recirculating flow, and pilot fuel is injected into the recirculating flow to sufficiently diffuse the pilot fuel and perform efficient combustion. Inject from This high-temperature combustion gas is injected into the combustor 53 of the ramjet engine R, preheats the air introduced into the combustor 53 through the diffuser 50, and furthermore, the introduced air and the main fuel in the combustor 53. Fire source for flammable mixtures.

Incidentally, in the ramjet engine R as described above, factors that make it difficult to start ignition when shifting to ramjet operation include (a) a high air flow velocity in the combustor, and (b) It is mentioned that the air temperature in the combustor is low, and (c) the static pressure of the air in the combustor is low. However, if the air temperature before combustion is increased, the flow velocity and static pressure of the air are affected. It has been confirmed that, for example, even if the air-fuel mixture becomes unstable at an air temperature of 300 K before combustion, the combustion continues at a low pressure which is a fraction of that at 1000 K.

Therefore, the ramjet engine R is
Even if the state of the introduced air is high speed, low temperature and low pressure compared to the ideal case, the introduced air and the main fuel are continuously mixed by being mixed with the pilot fuel by the action of heating by the combustion gas of the pilot burner B. The ramjet to be burned is activated.

When the temperature of the introduced air becomes extremely low, for example, due to the fact that the starting is performed at a high altitude, the pilot burner B rapidly heats the inside of the low temperature outer cylinder 3 to stabilize the combustion. Therefore, when the igniter 12 is ignited, oxygen is injected from the oxygen injection nozzle 13 toward the combustion space 5 for a short time to prevent the temperature of the combustion gas from being diluted by nitrogen in the low-temperature air, thereby keeping the temperature of the combustion gas high. To

Further, the pilot burner B stabilizes the continuous combustion in the recirculation flow region more reliably by causing the mixed flow of the pilot fuel and the introduced air to be contact-combusted by the catalyst 9, thereby enabling the ramjet operation. Thereafter, the combustion gas continues to be injected to function as a flame stabilizer of the ramjet engine R.

In the pilot burner B as described above, even if the air temperature is extremely low, the combustion is stabilized if the continuous combustion is started. Therefore, the oxygen used at the time of ignition corresponds to the time during which the igniter injects the flame. A sufficient amount is sufficient. Further, in the above-described embodiment, the example in which the pilot burner 1 is provided in the bypass 55 of the ramp portion 51 in the ramjet engine R is shown. In addition, as shown in FIG. 3, the pilot burner 1 is provided in the diffuser 50. In any case, in the pilot burner B as described above, the amount of air flowing into the outer cylinder 3 is
It is preferable that the total air flow into the combustor 53 be one tenth to one-seventh.

[0034]

As described above, according to the pilot burner of the present invention, the ramjet engine can be started at a high altitude and at a large angle of attack when the operating condition of the ramjet engine is high. Even if the air inside is difficult to ignite at high speed, low temperature and low pressure,
Performs stable ignition and stable combustion, raises the temperature inside the combustor when transitioning to ramjet operation with the combustion gas generated by pilot fuel combustion, and changes the air flow rate and static pressure inside the combustor. As a result, the combustion reactivity can be improved, and the reliability of the ramjet operation can be significantly increased.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a pilot burner according to an embodiment of the present invention together with a ramjet engine.

FIG. 2 is a cross-sectional view showing a configuration when the ramjet engine shown in FIG. 1 is operated by an IRR method.

FIG. 3 is a cross-sectional view of a ramjet engine showing a case where the pilot burner shown in FIG. 1 is provided in a diffuser.

[Explanation of symbols]

 B Pilot burner R Ram jet engine 1 Inlet 2 Outlet 3 Outer cylinder 4 Bluff body 5 Combustion space 6 Annular space 7 Blade 8 Pilot fuel injection nozzle 9 Catalyst 12 Igniter 13 Oxygen injection nozzle 53 Combustor

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Isao Funaki Water Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture (56) References JP-A-1-244153 (JP, A) JP-A Sho 50-76424 (JP, A) Japanese Patent Publication 34-3652 (JP, B1) Japanese Patent Publication 31-2252 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02K 7/10 F23R 3/12 F23R 3/20

Claims (2)

(57) [Claims] 1. A pilot burner for a ramjet engine, wherein an inlet on one end is directed toward an air introduction side of the ramjet engine and an outlet on the other end is opened in a combustor of the ramjet engine. An outer cylinder for forming a combustion space mounted in a state, and a bluff body having a curved front end portion is provided at a position near the inlet in the outer cylinder, and an annular flow is provided between the outer cylinder and the bluff body. While forming a path,
In the annular flow path, blades having a twist angle with respect to the axis of the outer cylinder are provided at predetermined intervals in a circumferential direction of the annular flow path, and a pilot fuel injection nozzle is provided at a rear end of the bluff body. A pilot burner, wherein the outer cylinder is provided with an igniter for injecting a flame toward a combustion space at a rear end side of the bluff body. 2. A pilot burner according to claim 1, wherein a catalyst for contact-burning a mixed flow of pilot fuel and introduced air is provided at a rear end of said bluff body, and a bluff body rear end is provided on said outer cylinder. A pilot burner provided with an oxygen injection nozzle directed toward the combustion space on the side.