Editing Pulsejet (section)

{{Short description|Engine where combustion is pulsed instead of continuous}}
{{Use dmy dates|date=February 2020}}
[[file:Pulse Jet Engine.PNG|thumb|300px|Diagram of a valved pulsejet. 1 - Air enters through valve and is mixed with fuel. 2 - The mixture is ignited, expands, closes the valve and exits through the tailpipe, creating thrust.3 - Low pressure in the engine opens the valve and draws in air.]]
{{Seriesbox aircraft propulsion}}

A '''pulsejet engine''' (or '''pulse jet''') is a type of [[jet engine]] in which combustion occurs in [[Pulse (physics)|pulse]]s. A pulsejet engine can be made with few<ref>{{cite web |url=http://gofurther.utsi.edu/Projects/PulseDE.htm |title=Pulse Detonation Engine |publisher=Gofurther.utsi.edu |access-date=3 March 2014 |archive-url=https://web.archive.org/web/20140904022120/http://gofurther.utsi.edu/Projects/PulseDE.htm |archive-date=4 September 2014 |url-status=dead }}</ref> or no [[moving parts]],<ref>{{cite web|url=https://news.google.com/patents/about?id=vOZsAAAAEBAJ |access-date=23 February 2016 |title=Google News }}{{dead link|date=June 2024|bot=medic}}{{cbignore|bot=medic}}</ref><ref>{{cite web|url=https://patents.google.com/patent/US6216446 |title=Patent US6216446 – Valveless pulse-jet engine with forward facing intake duct – Google Patents |access-date=3 March 2014}}</ref><ref>{{cite web |url=http://www.home.no/andreas.sunnhordvik/English/mechanical/valveless_e.htm |title=Valveless Pulsjet |publisher=Home.no |access-date=3 March 2014 |archive-date=6 September 2013 |archive-url=https://web.archive.org/web/20130906211013/http://www.home.no/andreas.sunnhordvik/English/mechanical/valveless_e.htm |url-status=dead }}</ref> and is capable of running statically (that is, it does not need to have air forced into its inlet, typically by forward motion). The best known example is the [[Argus As 014|Argus As 109-014]] used to propel [[Nazi Germany]]'s [[V-1 flying bomb]].

Pulsejet engines are a lightweight form of jet propulsion, but usually have a poor [[compression ratio]], and hence give a low [[specific impulse]].

The two main types of pulsejet engines use resonant combustion and harness the combustion products to form a pulsating exhaust jet that intermittently produces thrust. 

The traditional valved pulsejet has one-way valves through which incoming air passes.<ref>{{cite web | url=https://patents.google.com/patent/US2942412A/en | title=Pulse detonation jet propulsion }}</ref> When the fuel mix is ignited, the valves close, which means that the heated gases can only leave through the engine's tailpipe, thus creating forward thrust. 

The second type is the valveless pulsejet.<ref>{{cite journal|last=Geng|first=T.|author2=Schoen, M. A. | author3 = Kuznetsov, A. V. |author4= Roberts, W. L. |title=Combined Numerical and Experimental Investigation of a 15-cm Valveless Pulsejet|journal=Flow, Turbulence and Combustion | year = 2007 | volume = 78 | issue = 1 | pages=17–33|doi=10.1007/s10494-006-9032-8|bibcode=2007FTC....78...17G |s2cid=122906134}}</ref> The technical terms for this engine are acoustic-type pulsejet, or aerodynamically valved pulsejet.

One notable line of research includes the [[pulse detonation engine]], which involves repeated detonations in the engine, and which can potentially give high compression and reasonably good efficiency.