JPH0259296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a ram rocket engine, and more particularly to the arrangement of its air intake.

FIGS. 1 and 2 illustrate what is called a side air intake system as a typical conventional ram rocket engine.

In this ram rocket engine, the front end of a cylindrical engine case 1 is closed with an end plate 2, and the inside thereof is partitioned into front and rear sections by partition walls 3, with a fuel gas generating section 10 in the front section and an output section in the rear section. 20 respectively, and a rocket head such as a warhead is attached to the front end of the engine case 1 for flight.

In the fuel gas generating section 10, 11 is a fuel gas generating agent, 12 is an igniter for igniting the fuel gas generating agent, and 13 is a plurality of fuel nozzles formed in the partition wall 3.

The fuel gas generating agent 11 has a solid fuel and an oxidizing agent as its main components, and the oxidizing agent is mixed to the extent that it can self-sustainably decompose the solid fuel. of polybutadiene approx.
20wt%, metal powder as metal fuel approximately 40wt%,
Ammonium perchlorate (AP) as an oxidizing agent approx.
The composition consists of 40wt% and a small amount of additives. Since the metal fuel has a large calorific value, it contributes to increasing the specific impulse (ISP) of a rocket engine, and in addition to aluminum, copper, etc., recently boron has been particularly used for this purpose.

Next, in the output section 20, 21 is a combustion chamber, 22
23 is a secondary nozzle for injection, and 23 is a differential user. In this example, four differential users 23 are provided axially symmetrically on the outer circumference of the engine case 1, each of which has its front end opened forward and its rear end opened. fuel nozzle 1
An air intake port 24 is formed in the side surface of the engine case 1 immediately after the engine case 3.

Also, what is indicated by a two-dot chain line in FIG. 26 is a cover plate of, for example, a gunpowder breakage type that closes the air intake port 24, 27 is a primary injection nozzle that can be released rearward, and 28 is a primary nozzle that connects this primary nozzle to the secondary nozzle. For example, a gunpowder destruction type clamper is fixed to 22, and 29 is an igniter for igniting the propellant 25.

In this specification, the engine excluding the portions indicated by the two-dot chain lines is referred to as a ram rocket engine.

In the above configuration, when the igniter 29 is operated to ignite the propellant 25, the fuel gas is ejected from the primary nozzle 27 to start jetting, and the propellant 25 is burned out after a short time, during which time the propellant 25 is ignited. The ramrocket with the head attached is accelerated to the supersonic flight speed. When the igniter 12 is operated to ignite the fuel gas generating agent 11, the fuel gas generating agent 11 is combusted in a self-sustaining manner, resulting in decomposed gas of the binder containing a large amount of metal fuel (hereinafter referred to as a mixture of this decomposed gas and metal fuel). This gas is injected into the combustion chamber 21 through the fuel nozzle 13. Clamper 2 at the same time
8 to release the primary nozzle 27, and further break the cover plate 26 together with the insulator of the propellant 25 to open the air intake port 24, resulting in the state shown by the solid line in the figure. Here, outside air is forced into the differential user 23 by the ram pressure, and this is decelerated to about subsonic speed to recover the pressure and enter the air intake port 23.
Since the fuel gas is injected into the vicinity of the fuel nozzle 13 from the secondary nozzle 22, the fuel gas is reburned, and the high temperature combustion gas is ejected from the secondary nozzle 22, so that the ram rocket continues its injection.

By the way, such conventional ram rocket engines have a disadvantage in that the combustion efficiency of fuel gas, especially that of metal fuel, is low.The reason for this is explained as follows.

In other words, the combustion efficiency of metal fuel is affected by the ambient temperature, and in particular, the efficiency decreases significantly when the temperature drops below the ignition temperature of the metal, and in order to ensure its performance, ram rocket engines have to deal with the stoichiometric mixture ratio. Under the two conditions of taking in 3 to 4 times as much outside air as the amount of air being used, the conventional method injects the total amount of air taken in immediately after the fuel nozzle, which prevents excessive fuel gas from being injected. As a result of being diluted and causing a temperature drop, metal fuels become flame retardant before combustion is complete. 〜2200〓...〓 is the absolute temperature in degrees Celsius).

Figure 3 is a graph showing the above situation using calculated values, where the horizontal axis is the air-fuel gas mixture ratio (A/G), and the vertical axis is the specific impulse (ISP) and combustion temperature of the ram rocket engine. (Ts), and the basic conditions for calculation are as follows.

Fuel gas generating agent composition Polybutadiene binder 20wt% Boron 40wt% A P 40wt% Flight speed Matsuha number 2 (sea level) Intake air temperature 518〓 Total intake air pressure (Pto) 7.8 atm Ps/Pto 0.9 (Ps is combustion pressure) Combustion efficiency (φ) 0.9 As shown in this graph, the specific impulse, which represents the performance of a ram rocket engine, increases as the mixture ratio increases, but tends to level off around the same ratio of 25.
In the design, this mixing ratio was set to 15~15, taking into account the increase in air resistance of the differential user due to the increase in intake air.
Set around 20. On the other hand, the stoichiometric mixture ratio under the above conditions is approximately 5.5, and the combustion temperature Ts reaches its maximum point (approximately 2800〓) near this stoichiometric mixture ratio, and is below 2000〓 in the area of the above-mentioned design mixture ratio. As a result, the temperature falls below the ignition temperature of boron, making it impossible to obtain the desired combustion efficiency.

The curve represented by the broken line in the figure is included for reference to show that the specific impulse decreases significantly when the combustion efficiency φ decreases to 0.8.

Based on the above considerations, the present invention is constructed as follows in order to improve the combustion efficiency of fuel gas, particularly its metal fuel.

That is, in the ram rocket engine of the present invention, the air intake port is opened near the fuel nozzle at the front of the combustion chamber and at the rear of the fuel nozzle, and the intake air is distributed to these two parts, thereby increasing the air intake to the front part of the combustion chamber. The front part of the combustion chamber is designed to form a mixed combustion zone of the distributed intake air and fuel gas, and to create a temperature atmosphere within the mixed combustion zone that can almost complete the combustion of the metal fuel in the fuel gas. This is done by setting the mixing ratio of intake air and fuel gas to be distributed to each other.

An example will be explained.

In FIG. 4, 110 and 120 are a fuel gas generation section and an output section, which are respectively constructed in the front section and rear section of the engine case 1, as in the conventional ram rocket engine, and these two sections are opposite to each other. A pair of partition walls 103 and 1 provided
04, a distribution chamber 105 is formed between the partition walls 103 and 104, and the rear end of one diffuser 123a opens into the distribution chamber 105. A plurality of circular holes communicating from the distribution chamber 105 to the combustion chamber 121 are opened in the partition wall 104 axially symmetrically, and the same number of fuel nozzles 113 are protruded from the partition wall 10 in correspondence with the plurality of circular holes. The rear end of the hole faces the center of the circular hole. Therefore, the partition wall 104 has an annular air intake 12 surrounding the fuel nozzle 113.
4a is formed. Reference numeral 123b denotes another three differential users whose rear ends open into the side surface of the engine case 1 behind the air intake port 124a, forming another air intake port 124b there. Note that the differential users 123a and 123b
The arrangement relationship seen from the front is the same as that in FIG. 2, and the other configurations are also the same as the conventional one.

According to the above configuration, a part of the total intake air is taken from the diff user 123a through the distribution chamber 105 and from the air intake port 124a surrounding the fuel nozzle 113, so that the fuel gas is absorbed into the intake air at the front part of the combustion chamber. The air intake port 124 is mixed with the
A mixed combustion zone Z is created in front of a. Here, if the mixture ratio A/G of the rocket engine is set to 15 to 20 as described above, 1/4 of the total intake air is distributed to the mixed combustion zone Z, and the mixture ratio is equal to the stoichiometric mixture ratio. (about 5.5) about 4 to 5 in the vicinity
becomes. Therefore, as shown in FIG.
High temperature (Ts) of approximately 2800〓, which exceeds 2200〓) by a wide margin
This creates an atmosphere where boron fuel can be burned efficiently.

Furthermore, from Figure 3, the region where the atmospheric temperature of the mixed combustion zone can be maintained above the ignition temperature of boron fuel is the region where the mixture ratio A/G is about 5 to 11, that is, the region from around the stoichiometric mixture ratio to about twice the stoichiometric mixture ratio. And, although it is good for metal fuel to complete combustion in this zone,
When the ambient temperature is set to the above-mentioned high temperature as in the embodiment, combustion may continue for a sufficient period even downstream near the air intake port 124b.

Taking these into consideration, as well as taking into consideration the type of metal fuel, particle size, and other conditions, it is left to the discretion of the design to determine the distribution ratio of intake air, the volume of the mixed combustion zone, etc.

As explained above, the present invention distributes a part of the intake air to the front part of the combustion chamber to create a mixed combustion zone with a high ambient temperature there, so that even flame-retardant metal fuels such as boron can be efficiently used. Further, in the embodiment, a part of the intake air is injected from around the plurality of fuel nozzles, so that the mixture with the fuel gas is improved, and as a result, the combustion efficiency is further increased. Can be done.

[Brief explanation of the drawing]

Figure 1 is a front sectional view of a conventional side air intake type ram rocket engine, and Figure 2 is the same as Figure 1.
3 is a graph showing the combustion efficiency of metal fuel (boron) based on calculated values, and FIG. 4 is a front sectional view of an embodiment of the ram rocket engine according to the present invention. 113...Fuel nozzle, 121...Combustion chamber, 1
24a, 124b...Air intake, Z...Mixed combustion zone.

Claims (1)

[Scope of Claims] 1. The air intake port is opened near the fuel nozzle at the front of the combustion chamber and at the rear of the fuel nozzle, and the intake air is distributed to the front of the combustion chamber. The intake air and fuel gas are distributed at the front of the combustion chamber to form a mixed combustion zone, and to create a temperature atmosphere within the mixed combustion zone that can almost complete the combustion of the metal fuel in the fuel gas. A ram rocket engine with a set mixing ratio of intake air and fuel gas. 2. The ram rocket engine according to claim 1, wherein the air intake port near the fuel nozzle is opened around the fuel nozzle. 3. The ram rocket engine according to claim 1 or 2, wherein the metal fuel is boron and the mixing ratio is set in the vicinity of the stoichiometric mixing ratio or approximately twice the stoichiometric mixing ratio.