Combustor, jet engine, flying body, and operation method of jet engine
A combustor of a jet engine includes a fuel injector, an igniter for igniting a gas mixture of air and fuel, and a flame holder. The igniter is disposed in the flame holder. After an activation of the igniter, the igniter disappears, and a space after the disappearance functions as a flame-holding space.
1. A combustor in which fuel is to be burned by using air taken through an inlet, the combustor comprising:
an injector for injecting the fuel;
a depression portion defined in a wall surface of the combustor downstream of the injector;
an igniter provided in one part of the depression portion to ignite a gas mixture of the air and the fuel; and
a first flame-holding space provided in another part of the depression portion to keep a flame ignited by the igniter,
wherein the igniter is configured to disappear to form a second flame-holding space in the depression portion while the gas mixture of the air and the fuel is combusted, and
wherein at least a part of a periphery of the igniter is covered with a barrier which is distinct from the wall surface of the combustor, and which is configured to leave the depression portion by the igniter disappearing.
2. The combustor according to claim 1 , wherein a maximum length of the depression portion along a direction of a mainstream of the air taken through the inlet is defined as a length L, and a maximum depth of the depression portion is defined as a depth D, and
wherein the length L and the depth D are set such that L>D is satisfied.
3. The combustor according to claim 1 , wherein a part of the barrier is between the igniter and the wall surface of the combustor.
4. The combustor according to claim 1 , wherein the igniter is configured to autoignite and be activated due to heat and pressure created by compression of the air which has been taken through the inlet.
5. A jet engine comprising:
the combustor according to claim 1 ;
the inlet disposed forward of the combustor; and
a nozzle disposed rearward of the combustor.
6. A flying body comprising:
the jet engine according to claim 5 ; and
a thruster installed apart from the jet engine and configured to be activated to give thrust to the flying body before the jet engine is activated.
7. A rocket motor comprising the combustor according to claim 1 .
8. The combustor according to claim 1 , wherein the barrier is configured to contact the wall surface of the combustor.
9. An operation method of a jet engine, the jet engine comprising:
an inlet configured to take air;
a combustor configured to generate combustion gas by burning fuel by using the air; and
a nozzle configured to eject the combustion gas from a rearward side of the jet engine,
wherein the combustor comprises:
an injector for injecting the fuel;
a depression portion defined in a wall surface of the combustor downstream of the injector; and
an igniter provided in one part of the depression portion to ignite a gas mixture of the air and the fuel; and
a first flame-holding space provided in another part of the depression portion to keep a flame ignited by the igniter, wherein at least a part of a periphery of the igniter is covered with a barrier which is distinct from the wall surface of the combustor,
the operation method comprising:
taking the air through the inlet;
igniting the gas mixture of the air and the fuel by using the igniter;
having the barrier leave the depression portion by the igniter disappearing;
forming a second flame-holding space in the depression portion while the gas mixture of the air and the fuel is combusted by the igniter disappearing;
keeping the flame for burning the fuel by using the depression portion after the igniter is activated;
burning the gas mixture of the air and the fuel by using the flame which is kept; and
emitting the combustion gas generated by the burning from the nozzle.