Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!linus!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!hplabs!sri-unix!BRUC@MIT-MC From: BRUC%MIT-MC@sri-unix.UUCP Newsgroups: net.space Subject: Scramjets Message-ID: <1568@sri-arpa.UUCP> Date: Tue, 3-Jul-84 20:36:00 EDT Article-I.D.: sri-arpa.1568 Posted: Tue Jul 3 20:36:00 1984 Date-Received: Sat, 14-Jul-84 13:43:46 EDT Lines: 25 From: Robert E. Bruccoleri The idea behind a scramjet is that the flow of air through the combustion chamber is supersonic. Even in turbojets which operate at supersonic speeds, the air flow in the combustion chamber is subsonic. The air flow is slowed by the inlet and the compressor; after combustion, the heating then accelerates the air back up to supersonic speeds. The reason this distinction is important is that an ordinary flame cannot be maintained in supersonic flow (in effect, the molecules are moving too fast for any reaction to propogate). All I've heard beyond this is that no scramjet has generated more thrust than its own drag, presumably because the inlets and flame holders obstruct the flow. After hearing about this problem, I had a thought which I'd like those reading this digest who really know something about it to criticize. Since the propogation of combustion requires a chain reaction which continually maintains free radicals of oxygen and of the fuel, perhaps one could use an continuous ultraviolet laser operating at a frequency corresponding to the dissociation energy of one of the electrons on either oxygen or the fuel. This laser would maintain a population of radicals that would maintain combustion. Bob Bruccoleri (BRUC@MIT-MC)