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rkfire
Advanced Member
1716 Posts
Stratford, CT
USA
Suzuki
Bandit
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 Posted - 02/18/2014 : 4:09 PM
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quote:
Originally posted by greywolf
Explosive and internal combustion engine scientists and engineers use the same terms to mean different things. You'll just have to get used to it. Mixed usage is not uncommon in other fields either.
I had already preficed my remarks that it's entirely possible that different fields use different definitions for the same word.
I need not get used to anything, since I already proposed that possibility. So far, only the word detonation is in question. That wasn't the object of my disagreement though. It was whether an explosion occurs or not in the combustion chamber of a gasolene engine.
I am however saying, that no matter who is saying it, it's an explosion that occurs inside the combustion chamber, when you fill it with the proper ratio of misted gasolene, the proper ratio of air, swirl it, then compress it, and then introduce a spark at the right moment, the extreme pressure causes the piston to drive down the bore. |
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greywolf
 Moderator
1484 Posts
[Mentor]
Evanston, IL
USA
Suzuki
DL650AL2
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rkfire
Advanced Member
1716 Posts
Stratford, CT
USA
Suzuki
Bandit
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Posted - 02/19/2014 : 2:42 PM
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quote:
Originally posted by greywolf
Explosion is not the word used by engine people for combustion
A quick search on the SAE (Society of Automotive Engineers) website, entering "explosion", gave me 11 techical papers, in the first 5 pages of hits.
A number of the other papers use explosion as in, "the explosion of data" etc.
Some others were discussing diesel engines, and though pertinent, I didn't include those.
From the infancy of internal combustion engines and automobiles, through the 20's, 30's, 50's, 90's and 2000's, those papers used explosion to describe normal combustion.
The engineers in the early days had a good understanding, testing, high speed cameras filming the process through clear windows of test engines. The test engines allowed for testing ignition timing, fuel, compression ratios etc.
More modern papers talked about Heat Transfer and Thermal Loads In Small Internal Combustion Engines 1999, in it he says:
"A new approach to theoretically calculate the heat transfer based on the thermal vibrational convection theory is first proposed. The basic idea of this approach is that the heat transfer process can be correlated mainly with the thermal explosion and with the detonation wave produced by combustion."
Another 2014 paper talks about the possibilty of starting an engine by simply introducing fuel and spark to cylinders parked at the right spot in the cycle of a 4 stroke.
"Since the resultant mixture attained in the cylinders, when the first explosion occurs, is practically always the same (about 20 to 1 air-fuel ratio), the above equation gives a direct relation between the fuel-volatility data and engine-starting performance"
A 50's paper talking about the then new Buick V8.
"Improved combustion chambers and fuels permit higher compression ratios. Resulting higher explosion pressures call for a more rigid engine structure, which can be achieved on the V-type"
The other papers of various topics used explosion in the same manner. One older paper actually called it the "explosion stroke" rather than power stroke.
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rkfire
Advanced Member
1716 Posts
Stratford, CT
USA
Suzuki
Bandit
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Posted - 02/19/2014 : 4:28 PM
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There was another tidbit that I thought was interesting in those SAE technical papers. Although it didn't explain what mathematical law for bombs, that it talks about.
From 1923.
"A simple mathematical law, connecting the explosion-rate and turbulence and derived from experiments on bombs, is shown to be applicable to engines, and the manner of its application to the turbulence factor of any engine is indicated. This opens the way to quantitative experiments on turbulence in various designs of engine, hence to the development of designs for producing the greatest amount of turbulence, if such development should seem desirable, as turbulence is the factor that makes really high rotative speeds compatible with a good power output. An equally important factor in making explosions in engines occur more quickly than those in bombs is the heat produced adiabatically during the compression stroke."
That 2014 paper about self starting an engine using the power stroke of a cylinder or more, isn't exactly a new consept either. I recall that owners of some antique cars, notably Rolls Royce, said their engine would often enough start by themselves as soon as the ignition was turned on. |
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Gryphon Rider
Junior Member
45 Posts
Calgary, Alberta
Canada
Honda
Valkyrie Tourer
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Posted - 02/21/2014 : 3:56 PM
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Okay, now you guys are making me get fussy about the terminology of the combustion that happens inside an internal combustion engine. For the purposes of my missive posted earlier in this thread:
From dictionary.com. See definition 5:
explosion [ik-sploh-zhuhn]
noun
1. an act or instance of exploding; a violent expansion or bursting with noise, as of gunpowder or a boiler (opposed to implosion).
2. the noise itself: The loud explosion woke them.
3. a violent outburst, as of laughter or anger.
4. a sudden, rapid, or great increase: a population explosion.
5. the burning of the mixture of fuel and air in an internal-combustion engine.
6. Phonetics , plosion.
I guess it serves me right for trying to clearly answer a question in the "physics and theoretical" forum.  |
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scottrnelson
Advanced Member
6943 Posts
[Mentor]
Meridian, ID
USA
Honda
XR650L, 790 Adv R
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Posted - 02/21/2014 : 5:25 PM
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quote:
Originally posted by Gryphon Rider
From dictionary.com. See definition 5:
explosion [ik-sploh-zhuhn]
noun
5. the burning of the mixture of fuel and air in an internal-combustion engine.
How do we know dictionary.com isn't like wikipedia.com, where people can add whatever they want, and it's only if someone else cares enough that it gets corrected.
My Merriam-Webster's Collegiate Dictionary - Eleventh Edition (copyright 2009) doesn't include that particular definition. That's one reason why I keep paper dictionaries around - so I can look up the real definition of words, uncorrupted by the internet.  |
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gymnast
Moderator
4260 Posts
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Meridian, Idaho
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Sportster Sport
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Posted - 02/21/2014 : 8:26 PM
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There is a heck of a difference between a 4000 ft per second explosive pressure wave and a 200 ft per second flame propagation "explosion" in an internal combustion engine.
And then, at the top of the "explosive food chain" are the thermobaric explosives, none of which have anything to do with the topic of this thread except as surrealism. http://www.fas.org/man/dod-101/sys/dumb/fae.htm |
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JMalmsteen
 New Member
13 Posts
Long Island/Lancaster, NY/PA
USA
Harley-Davidson
XL1200
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Posted - 03/09/2014 : 3:58 PM
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| Here is what I have learned- cc's really are different if you are riding a cruiser or super sport bike. I recently got my first sport bike (a Yamaha FZ-09) and it's amazing what those 849 cc's are capable of in a triple engine. It's like a rocket. The 650 cc single S40 that I sold was like a tortoise compared to this new bike and the cc's aren't that different, but one has at most 30 hp and the other has 115 hp. Big difference. The 1200 cc Harley I have is maybe like a mid range tortoise compared to the Yamaha. |
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MotoGG
New Member
21 Posts
Murfreesboro, Tennessee
USA
Suzuki
GS500E
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Posted - 06/30/2014 : 10:05 PM
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http://www.dansmc.com/basics1.htm
Pay particular attention to the video of the inside of an engine. You can see it's a controlled flame not an explosion. Combustion can be controlled, you time when it happens, how it happens and where it happens (directionally as well). Not only that you are limiting the amount of energy released to optimize power and wear. In an engine detonation it's a mini explosion, you don't see a flam you see a flash. Deflagrate Is weaker that detonation but both describe and explosion not controlled combustion. It all about the intensity of the energy released. I hope this and the article above has clarified some questions. |
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MotoGG
New Member
21 Posts
Murfreesboro, Tennessee
USA
Suzuki
GS500E
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Posted - 06/30/2014 : 10:11 PM
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| Edit: you can google videos of internal combustions at work and they out a little camera in it and synchronize it so it not like a stroboscope. You can really see the flames ! |
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The Meromorph
Moderator
834 Posts
[Mentor]
White House, TN
USA
BMW
R1100RT
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Posted - 07/09/2015 : 10:11 AM
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Where the two definitions get even more confused is in the firing chamber of very large (usually naval) guns.
A lot of theory and a lot of work goes into design to get exactly the right balance between 'flame front propagation' and 'explosive detonation' of the propellant. Getting it wrong may have spectacular modes of failure... |
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Horse
Senior Member
258 Posts
Newbury, Berkshire
United Kingdom
BMW
R850RT
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Posted - 07/09/2015 : 12:17 PM
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quote:
Originally posted by greywolf
Explosive and internal combustion engine scientists and engineers use the same terms to mean different things. You'll just have to get used to it. Mixed usage is not uncommon in other fields either.
Deflagration
That's a good word, stuck in my head, it pops up and out when I want to appear to know something about the discussion :)
As you were.
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Discussion Topic |
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Horsepower vs CC