JP6037818B2 - Jet engine - Google Patents

Description

  The present invention relates to a jet engine. In particular, the present invention relates to a ramjet engine and a scramjet engine.

  A ramjet engine is known as a type of jet engine. A ramjet engine uses air compression by ram pressure associated with high-speed flight instead of a mechanical compressor. Such a ramjet engine is limited to a high speed region such as a supersonic region (Mach 3 to 5 is most efficient), but since a mechanical compressor is not used, the viewpoint of weight reduction of the fuselage To preferred.

  FIG. 1 schematically illustrates the configuration of a typical ramjet engine. The ramjet engine includes an inlet 110, a combustion chamber 120, a nozzle 130, and a throat section 140. The throat part 140 is provided on the wall of the combustion chamber 120 in order to adjust the air flow. More specifically, the throat part 140 includes a throat part 140A provided on the inlet 110 side and a throat part 140B provided on the nozzle 130 side.

  In the inlet 110 and the throat portion 140A, air is compressed by the ram pressure, and the supersonic airflow is decelerated to subsonic speed. In the combustion chamber 120, fuel is injected with respect to the subsonic air flow, and combustion (subsonic combustion) occurs. Then, combustion gas generated by the combustion is accelerated to supersonic speed at the throat portion 140B and the nozzle 130, and is ejected from the nozzle 130, and a reaction force is obtained by the reaction. One of the characteristic configurations of such a ramjet engine is a throat portion 140 provided for adjusting the air flow.

  On the other hand, when the flying speed exceeds Mach 5, when the supersonic airflow sucked is decelerated to subsonic speed, the pressure loss of the sucked airflow and the air resistance related to the aircraft increase, which is inefficient (worst The engine will be difficult to operate). Therefore, a technique has been proposed in which the supersonic air that has been sucked is guided to the combustion chamber 120 while maintaining the supersonic speed to perform supersonic combustion. This is called a scramjet (supersonic combustion ramjet) engine. Since the air flow is not decelerated below the sound speed over the entire engine from intake to exhaust, high engine performance is maintained in a wide Mach number range.

  FIG. 2 schematically shows the configuration of a typical scramjet engine. Compared to the ramjet engine shown in FIG. 1, one of the features of the scramjet engine is that the throat portion 140 is not provided.

  Patent Document 1 discloses a combined cycle missile engine system. The system operates the missile in five modes: (1) an integrated reverse hybrid rocket, (2) an air augmented hybrid rocket, (3) a ramjet / scramjet, (4) a dual injection hybrid rocket, and (5) Unit propellant rocket. By separating and controlling the oxidant and fuel, optimization of efficiency is achieved in each mode of operation.

Special table 2011-508126 gazette

  One object of the present invention is to provide a technique capable of realizing a jet engine having a wide operating range.

  [Means for Solving the Problems] will be described below using the numbers and symbols used in [Best Mode for Carrying Out the Invention]. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of [Claims] and [Best Mode for Carrying Out the Invention]. However, these numbers and symbols should not be used for the interpretation of the technical scope of the invention described in [Claims].

  In one aspect of the invention, a jet engine (1) is provided. The jet engine (1) includes a scramjet engine and a throat portion (40) formed on a combustion chamber wall (21) of the scramjet engine. When the throat section (40) is present, the jet engine (1) operates as a ramjet engine. While the jet engine (1) is operating as a ramjet engine, the throat portion (40) disappears with time.

  The throat portion (40) may be formed of a material whose shape disappears due to thermal or aerodynamic influence. The material may disappear regardless of ignition. The material may be an ablation material.

  A recess (50) may be formed in the combustion chamber wall (21). In this case, the throat portion (40) is formed to fill the recess (50) and protrude from the recess (50). The throat portion (40) may be bonded to the recess (50) with an adhesive (51). The throat portion (40) may be fixed by a screw (52) that does not protrude from the recess (50).

  According to the present invention, it is possible to realize a jet engine having a wide operating area.

FIG. 1 is a schematic diagram showing the configuration of a typical ramjet engine. FIG. 2 is a schematic diagram showing the configuration of a typical scramjet engine. FIG. 3 is a schematic diagram showing the configuration of the jet engine according to the first embodiment of the present invention. FIG. 4 is a schematic diagram for explaining the operation of the jet engine according to the first embodiment of the present invention. FIG. 5 is a schematic diagram for explaining the operation of the jet engine according to the first embodiment of the present invention. FIG. 6 is a table showing the shape disappearance speed of various materials. FIG. 7 is a table showing the shape disappearance speed required in various environments. FIG. 8 is a schematic view for explaining a jet engine according to the second embodiment of the present invention. FIG. 9 is a schematic diagram for explaining a jet engine according to a second embodiment of the present invention.

  A jet engine according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1. First Embodiment FIG. 3 is a schematic diagram showing a configuration of a jet engine 1 according to a first embodiment. The jet engine 1 includes an inlet 10, a combustion chamber 20, and a nozzle 30. A supersonic airflow flows into the inlet 10. The supersonic airflow is decelerated to subsonic speed or is guided to the combustion chamber 20 while maintaining supersonic speed. In the combustion chamber 20, fuel is injected into the air flow, and combustion occurs. And the combustion gas generated by the combustion is ejected from the nozzle 30, and the propulsive force is obtained by the reaction.

  The jet engine 1 according to the present embodiment further includes a throat-shaped throat portion 40. The throat portion 40 is formed on the wall 21 (combustion chamber wall) of the combustion chamber 20 in order to adjust the air flow. More specifically, the throat portion 40 includes a throat portion 40A provided on the inlet 10 side and a throat portion 40B provided on the nozzle 30 side.

  The throat portion 40 according to the present embodiment is formed so as to disappear automatically with time with flight. For example, the throat portion 40 is formed of a material whose shape disappears due to the thermal or aerodynamic influence of the air flow. Here, the thermal influence means an influence caused by the high temperature of the air flow downstream of the shock wave generated at the inlet 10, and includes “melting” and “vaporization”. The aerodynamic influence means an influence caused by contact with an air flow, and examples thereof include “wear” and “vaporization”. Examples of such a material for the throat portion 40 include ceramics that are easily worn and ablation materials.

  Next, the operation of the jet engine 1 according to the present embodiment will be described.

  As shown in FIG. 3, when the throat portion 40 is present, the jet engine 1 operates as a ramjet engine. That is, in the inlet 10 and the throat section 40A, air is compressed by the ram pressure, and the supersonic airflow is decelerated to the subsonic speed. In the combustion chamber 20, fuel is injected with respect to the subsonic air flow, and subsonic combustion occurs. Flight speed increases gradually.

  While the jet engine 1 is operating as a ramjet engine, as shown in FIG. 4, the throat portion 40 disappears over time and automatically. For example, the throat portion 40 disappears due to the thermal or aerodynamic influence of the air flow. As the throat portion 40 disappears over time, the characteristics as a ramjet engine gradually decrease, and instead, the characteristics as a scramjet engine gradually increase.

  While the flight speed further increases, the throat portion 40 disappears. Eventually, as shown in FIG. 5, the throat portion 40 disappears completely from the air flow path. In this case, the jet engine 1 operates as a scramjet engine. That is, the supersonic air flow sucked into the inlet 10 is guided to the combustion chamber 20 while being supersonic and the supersonic combustion is performed in the combustion chamber 20.

  As described above, the jet engine 1 according to the present embodiment operates as a scramjet engine after first operating as a ramjet engine. It can also be said that the jet engine 1 according to the present embodiment has a structure in which the throat portion 40 is added to the structure of the scramjet engine. The jet engine 1 operates as a ramjet engine while the throat portion 40 is present, and operates after switching to the scramjet engine after the throat portion 40 disappears.

  As described above, the jet engine 1 according to the present embodiment can operate alone as a ramjet engine or a scramjet engine. That is, the jet engine 1 having a wide operation area is realized.

  Moreover, according to this Embodiment, engine structures, such as the inlet 10, the combustion chamber 20, and the nozzle 30, can be shared by a ramjet engine and a scramjet engine. Therefore, the weight of the aircraft can be reduced.

  Furthermore, according to the present embodiment, the throat section 40 disappears automatically with flight. As a comparative example, consider a case where the throat portion 40 is deformed using a mechanical mechanism. In the case of this comparative example, there is a problem that a large-scale device is required, the engine structure becomes complicated, and the engine weight increases. In the present embodiment, such a problem does not occur.

  It is also conceivable to use a solid propellant as a material for the throat section 40. This is because the throat portion 40 automatically disappears by igniting the solid propellant. However, since the combustion of the solid propellant is very fast, the disappearance time of the throat portion 40 is also limited to a short time. This means that switching (shape change) from the ramjet engine to the scramjet engine occurs immediately. However, switching to the scramjet engine at a timing when the flight speed is not sufficiently increased is inefficient, and in the worst case, the operation is stopped. Another problem is that a large heat load is applied to the engine structure due to the combustion of the solid propellant.

  In consideration of such a problem, it is preferable to use a material other than the solid propellant as the material of the throat portion 40. For example, as described above, a material whose shape disappears due to the thermal or aerodynamic influence of the air flow is suitable. Such a material disappears without being ignited, so that the above problem in the case of a solid propellant is eliminated.

  FIG. 6 shows shape disappearance speed [unit: mm / second] regarding various materials suitable for the present embodiment. It can be seen that the shape disappearance rate varies depending on the type of material, the heating amount, and the shearing force. In other words, it is possible to arbitrarily adjust the shape disappearance speed by appropriately selecting the material. That is, it is possible to arbitrarily adjust the switching timing from the ramjet engine to the scramjet engine.

  FIG. 7 shows the shape loss rate required in various environments. Here, it is considered that the shape is changed (the throat portion 40 disappears) while the flight speed increases from 500 m / s (about Mach 1.7) to 1500 m / s (about Mach 5). Examples of the environment include airframe average acceleration and a necessary amount of shape change. Although the required shape disappearing speed varies depending on the environment, it can be seen that the requirement can be satisfied by adjusting the material or the like as shown in FIG.

  The two types of materials listed in FIG. 6 are both ablation materials. Ablation materials have an endothermic reaction upon disappearance. Therefore, the disappearance of the throat portion 40 formed of the ablation material contributes to cooling of the surrounding engine structure. As a result, the heat load on the surrounding engine structure is reduced, which is preferable.

2. Second Embodiment In the second embodiment, a technique for firmly holding the throat portion 40 is proposed so that the entire throat portion 40 does not peel from the combustion chamber wall 21 at a stretch.

  For example, as shown in FIG. 8, a recess 50 (recessed portion) is formed in the combustion chamber wall 21. The material of the throat portion 40 is formed so as to fill the concave portion 50 and protrude from the concave portion 50. And as FIG. 9 shows, the part of the throat part 40 which protrudes from the recessed part 50 lose | disappears by the thermal or aerodynamic influence of an air flow. According to such a structure, it is possible to prevent the entire throat portion 40 from being peeled off from the combustion chamber wall 21 at a stretch by catching the portion filling the recess 50.

  The throat portion 40 may be bonded to the recess 50 with an adhesive 51. In this case, the throat part 40 is held more strongly.

  Further, the throat portion 40 may be fixed by a screw 52. As shown in FIG. 9, the screw 52 is provided so as not to protrude from the recess 50. If the screw 52 protrudes from the recess 50, the protruding portion disturbs the air flow.

  The jet engine 1 according to the present invention is applicable to flying objects, aircraft, rockets, and the like.

  The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the above-described embodiments, and can be appropriately changed by those skilled in the art without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Jet engine 10 Inlet 20 Combustion chamber 21 Combustion chamber wall 30 Nozzle 40, 40A, 40B Throat part 50 Recessed part 51 Adhesive agent 52 Screw

Claims (7)

A scramjet engine,
A throat portion formed on a combustion chamber wall of the scramjet engine,
When the throat portion is present, the jet engine operates as a ramjet engine,
While the jet engine is operating as the ramjet engine, the throat portion disappears with time. The jet engine according to claim 1,
The throat portion is formed of a material whose shape disappears due to thermal or aerodynamic influences. The jet engine according to claim 2,
The material is a jet engine that disappears regardless of ignition. The jet engine according to claim 2 or 3,
The material is an ablation material. A jet engine according to any one of claims 2 to 4,
A recess is formed in the combustion chamber wall,
The throat portion is formed to fill the recess and protrude from the recess. The jet engine according to claim 5,
The throat portion is bonded to the concave portion with an adhesive jet engine. The jet engine according to claim 5 or 6,
The throat portion is fixed by a screw that does not protrude from the concave portion.

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