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January 14, 2010, 13:34 |
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#21 |
Member
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I got these information from book titled "a course in internal combustion engines" by M L Mathur. ignition is adversely affected by turbulence in SI engines that's why spark plug is given in recess.
I am a computer graduate who is crazy about automobiles which got me into developing this concept. I have also done CAD courses. so what is the current status of of your engine concept. are you doing it independent or your employer is helping you. |
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January 14, 2010, 13:59 |
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#22 |
New Member
Max Mitchell
Join Date: Jan 2010
Posts: 16
Rep Power: 16 |
No help from employer aside from the fact that I get paid to work for them.
Right now I have procured most of the parts for my engine that would have been very taxing to machine from scratch, such as pistons, liners, con rods, and I will soon have my crankshafts. I was planning on doing an in-depth CFD analysis on this engine before I start putting everything together and adjusting the port geometry. However, the only CFD software I have is COSMOS floworks, which apparently cannot do moving mesh modeling. So while cosmos flowworks is fine for stream engines, it is pretty useless at cycle analysis in a positive displacement machine. I am currently looking for a version of Ansys CFX to do this instead. If I have little luck, I may start simply building the engine, which is what I would have done in the past. My new years resolution was to do more initial mathematic investigation befor jumping into another project, but I may have to go back on that. As I mentioned earlier, I have conformed my design so that I may use commonly available parts for most of it. I will still have to fabricate manifoilds, and a "space frame" engine block, but I have done similar things in the past, so it should not be a big problem. Regarding the information from Mathur, I fear you may be misinterperating something here... The quote that you put in your post does not seem to support or refute the argument you have had in our recent discussion on the need (or lack there of) for spark advance. This just seems to be a comment about physically isolating the spark gap from areas of high local velocity. Also, in my experience, spark plugs are NOT recessed into a cavity. The gap between annode and cathode is typically protruding into the combustion chamber, in fact a teqnique to get a bit more power from an engine is to clock the plug so that the open side of the annode gap faces the incoming air stream (I don't know if that approach is actually effective). A wankel type rotary engine does have the spark plugs recessed into the rotor housing, but this is out of necessity becasue the apex seal would crash into the plug were it not sunken into the rotor housing. I believe this necessary design requirement is actually slightly detrimental to combustion efficiency in this engine, though not nearly as much as the dead space in the trailing edge of the cresent combustion volume. (read up on why the Mazda R26B LeMans racecar had 3 spark plugs per rotor and how it relates to the LeMans total fuel allowance rules at the time). |
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January 15, 2010, 02:05 |
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#23 |
Member
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best of luck for your project. "AVL fire" would be the ultimate software for engine design.
actually engine design involves lot of variable. not all variable should be at its best because of the interference between these variables; they are optimized. so some engines have recess for spark plug and others have swirl chamber like that |
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January 15, 2010, 09:17 |
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#24 |
New Member
Max Mitchell
Join Date: Jan 2010
Posts: 16
Rep Power: 16 |
does AVL FIRE have a built in modeler, or can I import from solidworks (through IGS or something). I am pretty handy with the solidworks modeling environment.
I have head a lot of good things about Ansys CFX. You would recommend FIRE over CFX? |
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January 15, 2010, 09:28 |
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#25 |
Member
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built in modeler of AVL fire may have limited features as in other CFD programs. but it supports step or iges files. Unlike CFX, AVL Fire is specifically designed by AVL for IC engines, major automakers use it for developing engines. it also has thermal analysis features.
I would like to know more about you, if you don't want to publish it; you can sent an email to delvezone@hotmail.com Last edited by dijinj; January 16, 2010 at 10:49. |
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Tags |
engine, rotary |
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