JPH06249070A - Method and apparatus for cooling gas film in high temperature section - Google Patents

Abstract

PURPOSE:To improve cooling efficiency, reduce flow of cooling medium and restrain engine performance from lowering by film cooling a position exposed to high temperature air current by the use of gas heated to high temperature. CONSTITUTION:Positions exposed to high temperature air current of a ramjet, rocket engine, etc., are film cooled by the use of gas heated to high temperature. For example, regenerative cooling is utilized for a heater 1 in a flow path of liquid hydrogen A. The liquid hydrogen A cools the wall surface of a combustion chamber, while it is heated and gasified to be jetted from a fuel injector 3 into the combustion chamber, mixed and burnt with air from an air intake port for jetting combustion gas C. A portion of high temperature gasified hydrogen is jetted from a film coolant injector 2 along the wall thereof to prevent the combustion gas contact with the wall of the injector and reduce the temperature rise of the wall. The flow of the coolant can be reduced by a simple constitution of disposing thus a heating source in a film coolant flow path.

Description

Detailed Description of the Invention

[00001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of cooling efficiency of a device using a high temperature gas such as a ramjet and a rocket engine.

[0002]

2. Description of the Related Art Conventionally, in a rocket engine or the like using high temperature gas, a liquid or a room temperature or low temperature gas is injected along the wall surface to protect the wall material from the high temperature gas, and the high temperature gas is directly applied to the wall surface. So-called film cooling has been used to prevent contact. in this way,
Although it is effective to reduce the wall temperature locally, the cooling efficiency is low, and a large amount of coolant was required to cool the entire engine.

When fuel is used as the coolant,
Excess fuel within the combustor is an unsuitable condition for combustion. If a non-combustion-related gas is used as the coolant, the propellant will be diluted, again making it unsuitable for combustion. Further, in any case, since a large amount of the coolant that is not involved in combustion is flowed, there is a problem that, for example, in a rocket engine, the performance is significantly reduced (specific thrust is reduced).

[0004]

SUMMARY OF THE INVENTION The present invention improves the cooling efficiency by reducing the coolant flow rate by increasing the temperature of the coolant used for film cooling, and as a result, the jet flow of scramjet, rocket engine, etc. In a propulsion engine, it is intended to obtain a gas film cooling method and a device therefor capable of suppressing deterioration of engine performance.

[0005]

The film cooling method of the present invention is characterized in that a portion of a ramjet, a rocket engine or the like exposed to a high temperature air flow is cooled by using a gas which is heated to a high temperature. And

A device therefor includes a coolant tank,
Further, in a cooling device having an injector for flowing the coolant in a film shape on a surface of a portion exposed to a high temperature air flow of a device, a heating device for the coolant is provided upstream of the injector.

[0007]

In contrast to the common sense that a low temperature coolant is used for cooling, the use of a high temperature gas as the coolant has the following advantages. As compared with the case of injecting the coolant at a low temperature, the injection speed of the coolant is increased and the mixing with the high temperature mainstream gas is suppressed, so that the range in which the film cooling is effective is expanded. Apart from the above effects, the cooling efficiency depends on the volume flow rate of the coolant, but at high temperature, the density decreases, the mass flow rate at the same volume flow rate decreases, and the required coolant flow rate further decreases. You can Any suitable heating source may be used, but the gas after regenerating and cooling the portion exposed to the high temperature gas can be used. Further, for a high-speed flying object in the air, the gas heated by the aerodynamic heating of the airframe can be used. It is also possible to raise the temperature by internal latent energy such as chemical reaction, external heat such as solar heat, nuclear energy and the like. For example, when using a gas whose temperature has been raised by releasing internal energy such as a chemical reaction, or which has been raised by an external energy source such as solar heat for film cooling of the nozzle portion of a jet propulsion engine,
A thrust increase can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. An example of a film cooling cycle of a supersonic ramjet (scramjet) embodying the present invention is shown in FIGS. FIG. 1 (e) shows an example of a film cooling cycle of a rocket engine embodying the present invention. The coolant A is, for example, liquid hydrogen. According to the conventional cooling method, the coolant A is injected along the engine wall surface at a low temperature. In the film cooling of the present invention, the coolant A is heated by a heat exchanger shown by 1 in the drawing, which is provided in the middle of the flow path, or a heating device by a chemical reaction, external energy or the like.

The embodiment of FIG. 1 (a) is an example in which regeneration cooling is used as the heating device 1 in the flow path of liquid hydrogen A. Liquid hydrogen cools the wall surface of the combustion chamber while being heated and vaporized. The fuel gas is injected into the combustion chamber from the fuel injector 3, mixed and burned with the air from the air intake port, and the combustion gas C is ejected. A part of the vaporized high-temperature hydrogen is injected from the film coolant injector 2 along the vessel wall to prevent contact between the combustion gas and the vessel wall and reduce the temperature rise of the vessel wall. In the embodiment shown in FIG. 1B, the heating device 1 is a combustor, and the coolant A mixes with the reactant A ′ and burns to raise the temperature of the coolant. E is the fuel. In the embodiment of FIG. 1 (c),
The heating device 1 includes a heat source such as a catalyst or nuclear power, and heats the coolant A. In the embodiment of FIG. 1 (d), the heating device for the coolant A is a heat exchanger for the airframe wall that is at a high temperature due to aerodynamic heating or the like, and is a device for cooling the airframe.

Consider the case where hydrogen is used as the coolant in the scramjet. FIG. 2 shows the cooling flow rate when the total mainstream temperature is 6500 K, the mainstream Mach number is 4, the engine length is 5 m, the engine circumference is 3.5 m, and the allowable wall material temperature is 1500 K. In the figure, the horizontal axis represents the total temperature of the coolant hydrogen, and the vertical axis represents the equivalence ratio of the cooling hydrogen. At this time, the stoichiometric mixing ratio hydrogen flow rate is 18 kg · s ⁻¹ . It can be seen that the required coolant flow rate decreases with increasing coolant total temperature.

FIG. 1 (e) shows an embodiment of a rocket engine, in which a fuel A such as liquid hydrogen is heated by a heat exchanger 1 for cooling a wall of a combustion chamber and is discharged from a propellant injector 3 together with a reactant B. It is injected into the combustion chamber. A part of the fuel A is injected as the coolant 2 along the vessel wall.

FIG. 3 shows the increase of the cooling effect in the rocket engine. The mainstream Mach number is 0.01, the total mainstream temperature is 3500 K, the engine length is 0.4 m, and the engine radius is 0.2 m. Again, it can be seen that the required coolant flow rate decreases as the coolant temperature rises. Unlike in the case of scramjet, the optimum coolant temperature exists because the main flow velocity is not high, but it is much higher than the liquid temperature, and the effect of increasing the temperature of the coolant appears.

FIG. 4 shows the hydrogen flow rate of the scramjet in the form of an equivalence ratio when the coolant heated in the regenerative cooling shown in FIG. 1A is used for film cooling. Since it is used in combination with regeneration cooling, cooling is performed with hydrogen used for combustion, and the hydrogen flow rate exceeding the equivalence ratio of 1 is the extra hydrogen flow rate required for cooling. The equivalence ratio is constant in the low Mach number region because the engine is burned in stoichiometric mixture ratio. It can be seen that, compared with the case of film cooling alone or the case of reproduction cooling alone, the required film hydrogen flow rate is much smaller in film cooling using high-temperature hydrogen after reproduction cooling for cooling. Note that the hydrogen flow rate in the case of film cooling alone in FIG. 4 is one tenth as shown in the figure. For example, when the flight Mach number is 8, the equivalence ratio is 9.

The net specific thrust at this time is shown in FIG. It can be seen that the specific thrust is increased as compared with the case of the film cooling alone or the case of the regenerative cooling alone because the excess coolant flow rate is reduced. Fig. 6 shows the coolant at this time,
That is, it indicates the fuel supply pressure. The coolant supply pressure is also reduced due to the reduced coolant flow rate. by this,
The weight of the engine can be reduced. Also, the power of the coolant supply system can be small, and the influence on the specific thrust of the turbine exhaust etc. can be reduced.

[0015]

In the film cooling of the present invention, the flow rate of the coolant can be reduced by the simple structure of arranging the heating source in the film coolant channel as described above.
Not only can engine performance such as specific thrust be improved, but its ripple effect can also contribute to weight reduction of the engine structure. It should be noted that this technology is applicable not only to the engine but also to an apparatus using a gas flowing at high temperature.

[Brief description of drawings]

FIG. 1 is an operation conceptual diagram showing an example of a coolant cycle of a scramjet engine and a rocket engine embodying the present invention. (A) is an example of regenerative cooling,
(B) is an example in which the temperature is increased by using a coolant combustor, (c) is an example in which a heat source such as a catalyst or nuclear power is used, and (d) is increased by external energy such as aerodynamic heating. For example, (e) is an example using a coolant which is a fuel after regeneration cooling in a rocket engine.

FIG. 2 is a graph showing an example of the relationship between the coolant temperature and the required coolant flow rate at supersonic speed.

FIG. 3 is a graph showing an example of a relationship between a coolant temperature and a required coolant flow rate at a subsonic speed.

FIG. 4 is a graph showing an example of the relationship between flight speed and hydrogen flow rate in the coolant cycle shown in the embodiment of FIG. 1 (a).

5 is a graph showing an example of the relationship between flight speed and net specific thrust in the case shown in FIG.

6 is a graph showing an example of the relationship between the flight speed and the hydrogen supply pressure in the case shown in FIG.

[Explanation of symbols]

1 Heating Device 2 Film Coolant Injector 3
Fuel injector A Coolant B Air or reactant C
Combustion gas E fuel

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuo Jinzai Kimigata, Kakuda City, Miyagi Prefecture Koganazawa 1 Kanazawa, Kakuda Branch, Institute of Aerospace Engineering, Japan Science and Technology Agency (72) Yoshio Wakamatsu Kimiyo, Kakuda City, Miyagi Prefecture Koganazawa No. 1 within the Kakuda branch of the Institute of Aeronautics and Space Technology, Science and Technology Agency (72) Inventor Toshihito Saito Kimigata, Kakuda City, Miyagi Prefecture Koganezawa No. 1 inside the Kakuda branch of the Institute of Aerospace Engineering (72) Inventor Takahashi Masahiro No.1 Kanazawa, Kanagata, Kakuda City, Miyagi Prefecture Kakuda Branch, Aerospace Research Institute, Science and Technology Agency

Claims (2)

[Claims] 1. A method for cooling a gas film, which comprises cooling a film exposed to a high-temperature air flow with a gas heated to a high temperature. 2. A cooling device having a coolant tank and an injector for causing the coolant to flow in a film form on a surface of a portion of the device exposed to a high temperature air flow, in the upstream of the injector,
A gas film cooling device comprising a heating device for a coolant.