JP2018109378A - Flame stabilizing cavity of scram-jet engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flame stabilizing cavity of a scram-jet engine, the cavity that is small and reduced in pressure loss compared with a conventional one, is compatible with high speed, can realize stable combustion in a wide operating range, can avoid thermal choking, is low in failure by mechanical moving parts, and eliminates the need for a large-scale mechanical mechanism.SOLUTION: A cavity is used for flame stabilization in the internal supersonic flow of a scram-jet engine for use in a wide area from a supersonic speed to a hypersonic speed. A mechanism is employed for heating an induction heating element installed in a flame stabilizing cavity and generating heat by an induced current in accordance with the operating conditions of the scram-jet engine by the induction coil installed in the outside of the cavity, and thereby the certainty of the flame stabilization is improved and the thermal choking is avoided.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a flame holding cavity of a scramjet engine.

In order to reliably hold the flame of the combustion gas containing the unburned fuel that has been ignited, a flame holding cavity is used in the scramjet engine.
In order to reliably hold the flame over a wide operating range and to avoid thermal blockage, it is necessary to move the flame holding cavity in the flow direction of the combustion gas according to the operating conditions.

  However, in the conventional scramjet engine, a large mechanical mechanism is required to move the flame holding cavity, and it is difficult to suppress the weight of the mechanism and to respond at a high speed.

Japanese Patent Laid-Open No. 02-275051 JP 2012-207610 A

  The problem to be solved is that a large mechanical mechanism is required to move the flame holding cavity, which makes it difficult to control the weight of the apparatus and to respond at high speed. .

  The present invention has a mechanism that makes the flame holding performance of the flame holding cavity variable without moving the flame holding cavity, so that it is smaller in size and less in pressure loss and can respond at high speed. A flame holding cavity for a scramjet engine that can achieve stable combustion over a wide operating range, avoid thermal blockages, has a low risk of failure due to mechanically moving parts, and does not require a large mechanical mechanism Providing the most important feature.

  The flame-holding cavity of the present invention is smaller and has a lower pressure loss than the conventional one by changing the temperature of the circulating vortex, which is a gas circulating in the flame-holding cavity, according to the operating conditions of the scramjet engine. Responsible for high speed, stable combustion can be realized in a wide operating range, thermal blockage can be avoided, the risk of failure due to mechanically moving parts can be reduced, and no large mechanical mechanism is required There is an advantage.

FIG. 1 is a schematic cross-sectional view of a flame holding cavity installation portion of a scramjet engine. Example 1 FIG. 2 is a schematic cross-sectional view of a flame holding cavity installation portion of a scramjet engine. (Example 2)

  The purpose of realizing stable combustion in a wide operating range of the scramjet engine and avoiding thermal blockage is to reduce the size of the circulating vortex, which is the gas circulating in the flame-holding cavity, by reducing the temperature. Stable combustion can be realized in a wide operating range with low pressure loss and high speed response, thermal blockage can be avoided, failure risk due to mechanical moving parts can be reduced, and large mechanical mechanism Realized by a mechanism that eliminates the need for

  FIG. 1 is a schematic cross-sectional view of a flame holding cavity installation portion 2 of a scramjet engine.

  The flame holding cavity 1 of the scramjet engine according to the first embodiment includes a cylindrical induction heating element 7 that generates heat by an induced current in the flame holding cavity 1, and a flame holding cavity bottom face 9 made of a nonmagnetic material. With the induction heating coil 8 installed at a symmetrical position, the induction heating element 7 generates heat in accordance with the operating conditions of the scramjet engine, thereby quickly stabilizing the combustion in a wide operating range. This is direct heating in which the induction heating element 7 is heated by Joule heat generated by the induction current, and in principle, the amount of heating can be changed rapidly.

  In the combustion gas 6 containing unburned fuel flowing at supersonic speed in the right direction indicated by an arrow into the flow path formed by the flame holding cavity installation wall surface 3 and the flame holding cavity installation wall upstream wall surface 4 from the left side of the figure The fuel is already mixed from a fuel nozzle (not shown) and is ignited by an ignition device (not shown), and a circulation vortex of combustion gas is generated in the flame holding cavity 1. The circulation vortex serves as a heat source, and the flame holding cavity 1 serves as a flame holder.

  The induction heating coil 8 generates a predetermined magnetic flux by a high-frequency power source controlled by a control device (not shown), whereby the induction heating element 7 generates Joule heat, and heat is transferred from the induction heating element 7 to the circulation vortex to circulate. The temperature of the vortex increases. As a result, more heat is transferred from the circulation vortex to the combustion gas 6 including unburned fuel through the opening 10 of the flame holding cavity 1, and the combustion of the combustion gas is promoted to make the flame more stable.

  By controlling in this way, the amount of heat transferred from the opening 10 of the flame holding cavity 1 to the combustion gas 6 containing unburned fuel can be controlled. Therefore, by generating a predetermined magnetic flux in the induction heating coil 8, the amount of heat transferred from the open portion 10 of the flame holding cavity 1 to the combustion gas 6 containing unburned fuel is rapidly increased and decreased, and compared with the conventional method. It is possible to realize stable combustion in a wide operating range that can respond to the above, and to reduce the risk of failure due to mechanically movable parts. By rapidly reducing the magnetic flux generated in the induction heating coil 8, the amount of heat transferred from the open portion 10 of the flame holding cavity 1 to the combustion gas 6 containing unburned fuel can be rapidly reduced, and the flame holding cavity It is possible to avoid the occurrence of thermal blockage downstream of the flow path formed by the flame holding cavity installation wall surface 3 and the flame holding cavity installation wall downstream wall surface 5 downstream of 1. In addition, by setting the temperature of the circulating vortex higher, by keeping the area of the opening 10 of the flame holding cavity 1 small from the beginning, the pressure loss caused by the cavity can be kept low, improving the engine performance. Can be made.

Here, the induction heating element 7 is not limited to one in the magnetic flux generated from the induction heating coil 8, and a plurality of induction heating elements 7 may be installed, and the shape of the cylinder is not limited to the cylinder. Further, the induction heating coil 8 is not limited to one.

  FIG. 2 is a schematic cross-sectional view of the flame holding cavity installation portion 2 of the scramjet engine.

  In the flame holding cavity 1 of the scramjet engine according to the second embodiment, the thermal blocking is more reliably avoided by applying the thermal barrier coating 11 to the inner surface of the flame holding cavity 1.

  In order to avoid the occurrence of thermal blockage downstream of the flow path formed by the flame holding cavity installation wall surface 3 and the flame holding cavity installation downstream wall surface 5 downstream of the flame holding cavity 1, induction heating is performed. The coil 8 is controlled so as to rapidly reduce the magnetic flux generated in the induction heating coil 8 based on a control signal transmitted by a control device (not shown).

By controlling in this way, the Joule heat generated by the induction heating element 7 is rapidly reduced, and the amount of heat transmitted from the induction heating element 7 to the circulation vortex of the combustion gas generated in the flame holding cavity 1 is rapidly reduced. As a result, the amount of heat transferred from the opening 10 of the flame-holding cavity 1 to the combustion gas 6 containing unburned fuel can be rapidly reduced, and the flame-holding speed can be increased faster than when the thermal barrier coating 11 is not applied. It is possible to avoid the occurrence of thermal blockage downstream of the flow path formed by the flame holding cavity installation wall surface 3 and the flame holding cavity installation downstream wall surface 5 downstream of the cavity 1. Not only when the Joule heat generated by the induction heating element 7 decreases, but also when it increases, by applying a thermal barrier coating 11 to the inner surface of the flame holding cavity 1, the flame holding cavity 1 and the circulating vortex Heat exchange between the two and the temperature of the circulating vortex can be controlled at a higher speed, and combustion can be stabilized at a higher speed in a wide operating range.

DESCRIPTION OF SYMBOLS 1 Flame holding cavity 2 Flame holding cavity installation part of scramjet engine 3 Flame holding cavity installation part wall surface 4 Flame holding cavity installation part upstream side wall surface 5 Flame holding cavity installation part downstream side wall surface 6 Including unburned fuel Combustion gas 7 Induction heating element 8 Induction heating coil 9 Flame holding cavity bottom
10 Opening 11 Thermal barrier coating

Claims (2)

  A flame holding cavity of a scramjet engine comprising an induction heating element that generates heat by an induced current in the flame holding cavity.   The flame holding cavity according to claim 1, wherein a thermal barrier coating is applied to an inner surface of the flame holding cavity of the scramjet engine.

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