Pulse jet engine

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A pulse jet engine (or pulsejet) is a type of jet engine in which combustion occurs in pulses. Pulsejet engines can be made with few [1] or no moving parts,[2][3][4] and are capable of running statically.

There has been a great deal of research on pulsejet engines recently,[by whom?] as more people realize the practical benefits of their capabilities. One such line of research[attribution needed] uses pulsejet engines to study and simulate various pulse detonation engine phenomena more cost-effectively and on a smaller scale[vague].



Pulsejet engines are a type of jet engine which has few or no moving parts, and which can operate statically. There are two main types of pulsejet engines, both of which use resonant combustion and harness the expanding combustion products to form a pulsating exhaust jet which produces thrust intermittently.

Valved engines use a mechanical valve to control the flow of expanding exhaust, forcing the hot gas to go out the back of the engine through the tailpipe only, and allow fresh air and more fuel to enter through the intake. The other type of pulsejet, valveless pulsejets, have no moving parts and use only their geometry to control the flow of exhaust out of the engine. Valveless engines expel exhaust out of both the intakes and the exhaust, most try to have the majority of exhaust go out the longer tail pipe, for more efficient propulsion.

The valved pulsejet comprises an intake with a one-way valve arrangement. The valves prevent the explosive gas of the ignited fuel mixture in the combustion chamber from exiting and disrupting the intake airflow, although with all practical valved pulsejets there is some 'blowback' while running statically and at low speed as the valves cannot close fast enough to stop all the gas from exiting the intake. The superheated exhaust gases exit through an acoustically resonant exhaust pipe. The valve arrangement is commonly a "daisy valve" also known as a reed valve. The daisy valve is less effective than a rectangular valve grid, although it is easier to construct on a small scale.

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