effect of flame speed on co-02 mixture with water vapor
effect of flame speed on co-02 mixture with water vapor
(OP)
http://www.not2fast.com/NACA/naca-report-531.pdf
Maybe this is why there are some claims of more power with water vapor injection?
Maybe this is why there are some claims of more power with water vapor injection?





RE: effect of flame speed on co-02 mixture with water vapor
The link seems to be broken.
Why are you linking to that site instead of directly to NACA
Regards
Pat
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RE: effect of flame speed on co-02 mixture with water vapor
Thats where I found it.
RE: effect of flame speed on co-02 mixture with water vapor
Here, I'll stick it in our own upload spot for you.
Best to you,
Goober Dave
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RE: effect of flame speed on co-02 mixture with water vapor
Thanks a lot. I should slap myself for not coming across this paper in my younger days.
Anyway, I am trying to get any technical publication with regard to the WW2 Japanese long lance torpedo. The engine is rumored to work on oxygen and water. It travels faster and further than any other known torpedoes in its era including its ally the Nazi german.
RE: effect of flame speed on co-02 mixture with water vapor
As for the Japanese torpedo engines. It would be easy too backfeed the steam exhaust too make that engine perform and even last.
RE: effect of flame speed on co-02 mixture with water vapor
Regards
Pat
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RE: effect of flame speed on co-02 mixture with water vapor
There have been many studies of water injection in normally aspirated SI engines and studies of water in diesel engines.
azmios, Several torpedoe designs used IC engines that ran on hydrogen peroxide and a hydrocarbon. The same combination is also good rocket propellant. Hydrogen peroxide is NOT a cheap source of oxygen.
RE: effect of flame speed on co-02 mixture with water vapor
If you notice, people like me and Slim3 always believe that there must be some other unexplained phenomena that increases the horsepower more than what is achievable by just extending the knock limit. So far, no researchers have investigated the effect of water itself in the combustion chamber.
I am also aware of Ricardo's report about the decreased in peak pressure. However, up until now, nobody that I am aware of has investigated whether the decrease in peak pressure is contributed by the present of water in the combustion chamber that might have caused slowed down the flame propagation and to cause the unburned fuel to occur.
Somehow, I still think that oxygen using PSA is the way to go as it can be produced only when it is needed. I read about how the WW2 Japanese submarines produce the required oxygen for the torpedoes in the middle of ocean using an oxygen generator. I am very much interested to learn how they control the extreme temperature increase inside the combustion chamber. That's why, both high residual gas and water injection are part and parcel for oxygen combustion.
RE: effect of flame speed on co-02 mixture with water vapor
You appear to believe that the world is oblivious to explanations and possibilities. "So far, no researchers have investigated the effect of water itself in the combustion chamber" On the contrary, brilliant minds have studied and are studying these issues constantly. The effects of excess water in the combustion process has been the focus of intense study for SI and CI engines. These inquiries began in the first decades of the 20th century. If you do enough research you will find recent studies by labs all over the world including some of the nuclear plasma labs that have the supercomputers to model burn processes.
RE: effect of flame speed on co-02 mixture with water vapor
Bottom line is you cannot change the total energy released without resorting to over unity. You can only change when, how fast, in what form and where it is released. This can allow you to extract more work with less waste from it.
Regards
Pat
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RE: effect of flame speed on co-02 mixture with water vapor
I have my own reason for not using hydrogen peroxide. It needs to be reacted with enough activation energy before we can use it. Oxygen is much simpler to use and control.
When I made my comment, you have to look into the context of why injecting water makes more power even when there is no change in energy content of the fuel injected. i also do research in water so what you're alleging is more of myself contradicting of what I am doing for living.
All the papers that I have, mentioned about the power increase but none made convincing scientific explanations on why the power increases even if the ignition timing, boost, energy content remain the same. If you reckon that many have done so, proof me to be wrong by showing the link to the technical papers, I will be more than happy to buy the papers.
RE: effect of flame speed on co-02 mixture with water vapor
If you have done your own research on water injection and come up with some of the conclusions you have expressed, you need to go back and try again. If you know what you are doing you should be able to provide some "convincing scientific explanations on why the power increases" or doesn't increase. Other people have provided explanations.
Do your own paper chase.
RE: effect of flame speed on co-02 mixture with water vapor
Which paper claims "the power increases even if the ignition timing, boost, energy content remain the same." ??
Sometimes the note about ignition timing being adjusted for best torque or knock limited power during testing does not appear under each Figure or Table. For no ignition timing adjustment to be required I'd expect the initial, pre-water setting to have been creating angry unstable combustion, or for the testing to have required maintaining less than full throttle.
Dan T
RE: effect of flame speed on co-02 mixture with water vapor
There you go again, why do you have to resort into personal attack?
RE: effect of flame speed on co-02 mixture with water vapor
There is another debate going on in water+methanol by Slim3. Slim3 reported that there is no change in parameter other than injecting the water+methanol.
RE: effect of flame speed on co-02 mixture with water vapor
This figure is from NACA research memorandum E6106, which investigated methods of limiting peak cylinder head temperature in cylinder 10 of a Wright R-2800, where this cylinder would otherwise exceed the manufacturer's recommended temperature limit at military power, as installed in a P47G aircraft. One method investigated was water/ethanol injection into the intake pipe of cylinder 10. At the top of the figure above, the effect of coolant injection rate (x-axis) on net BHP is shown. The BHP indicated is for the entire engine, so the changes in BHP are due to changes in cylinder 10 only, since that is the only cylinder in which operating conditions were altered. It can be seen that, as coolant flow increased from 0 to 40lb/hr, cylinder 10 power decreased by 30 BHP. Assuming that cylinder 10 was contributing an equal share of the total engine power initially, this is a reduction of approximately 35%.
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: effect of flame speed on co-02 mixture with water vapor
RE: effect of flame speed on co-02 mixture with water vapor
RE: effect of flame speed on co-02 mixture with water vapor
Anyway, maxc, my direct experience in compensating a spark ignited natural gas engine for ambient humidity is that, for excellent physical reasons, when no compensation is made for atmospheric humidity, power monotonically decreases with increasing specific humidity, from 0 on up as high as you like. There are two direct effects. One is, water vapour displaces other molecules in the atmosphere, in accordance with its concentration, which means less oxygen is available, by partial pressure, in proportion to water vapor that is present. The SAE net power correction formula takes this into account, so that power is corrected to the observed dry barometric pressure, i.e. the partial pressure of water vapour is subtracted out in the denominator of the correction factor, since the numerator assumes dry air (zero humidity). The above explanation pertains to an engine running at or rich of stoichiometry. The effect of humidity on an engine running lean of stoichiometry is more complicated and application specific, since since the effect of humidity is not the same for all methods that are used to control air/fuel ratio.
The second effect is a little more subtle, but also easy to understand. Water vapour in the charge acts as an inert diluent, effectively slowing the combustion rate and reducing peak temperature. This is exactly the same effect as EGR, for the same reason. With no change in operating conditions to compensate, slowing the combustion means it will be phased later in the cycle. Peak pressure, rate of pressure rise, heat release rate and effective expansion ratio will be reduced accordingly. The net energy release will be the same, but the energy is converted less efficently to pressure pushing down the piston; as a result, power correlates inversely with ambient humidity, assuming all control parameters are held constant.
"Schiefgehen will, was schiefgehen kann" - das Murphygesetz
RE: effect of flame speed on co-02 mixture with water vapor
There are other oxygen rich compounds that require heating or catalysts to decompose. You can use a catalyst to set H2O2 off. You get a lot of heat and free oxygen. If anything that can burn is around, you get a very hot fire.
No compounds like these are good as oxidizers in the type of engine you are promoting because they cost money. Efficiency of operation in universal power plants is pursued for reasons of economy. To get a better burn by using an expensive oxidizer in place of a free oxidizer makes no sense whatsoever. It is only appropriate for special applications like anaerobic environments under water or at very high altitudes. For this second purpose, they investigated pure oxygen for aircraft engines. They found that pure oxygen is very bad for combustion due to causing detonation. A MUCH better alternative was Nitrous Oxide which is a low pressure containment liquid. Nitrous is used in cars for power. It is way NOT economical compared to air.
RE: effect of flame speed on co-02 mixture with water vapor
The time from spark too flamefront.
RE: effect of flame speed on co-02 mixture with water vapor
I am about to end this charade.
Regards
Pat
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RE: effect of flame speed on co-02 mixture with water vapor
Regards Mark
RE: effect of flame speed on co-02 mixture with water vapor
I don't think azmios will be back to further disrupt this or any other thread.
Regards
Pat
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RE: effect of flame speed on co-02 mixture with water vapor
Speculating, engines often operate at a point of marginal preignition or detonation. It may be completely unnoticed. An increase in humidity could reduce the tendency to detonate and the effect will be a slight increase in power. Other than this effect, humidity constitutes a substitution of water for air and a proportionate reduction of oxygen thus a reduction in power. The loss should be very small since 100% humidity at 100 degrees F is only around 1% of a substitution. Notice one thing, water as a gas, humidity, does not have a cooling effect due to evaporation.
Gasoline tends to break down under the heat of the pre-spark compression. Unstable molecular fragments form and they begin to react with the oxygen in the mixture, producing even more heat. These reactions are called "cold flame reactions". They increase the tendency to detonate and they represent a slight direct loss of power since they occur before the optimum ignition point. Humidity, water in the mix, slows cold flame reactions.
One last thing, fog is another matter altogether. It's not just 100% humidity. There are droplets of water in the air.
RE: effect of flame speed on co-02 mixture with water vapor
In your 15 October post you said "All the papers that I have, mentioned about the power increase but none made convincing scientific explanations on why the power increases even if the ignition timing, boost, energy content remain the same."
I am still interested in which paper claims "the power increases even if the ignition timing, boost, energy content remain the same."
Slim3's descriptions of his experiments don't really qualify. (Although a water/alcohol mix would seem to bring the alcohol's BTUs to the party.)
I offer the the 1943 NACA paper as an example of the typical testing I'm aware of. 4 stroke, spark ignition, gasoline fueled. Appearing pretty frequently are phrases like "permissible decrease in octane number" and "maximum permissible power." The ignition timing was held at 20 BTDC and the inlet temp was held at 250F. They just played with boost, throttle position, A/f ratio and amount of water injected. On page 60 it talks about power, indicated mean effective pressure, or inlet pressure (boost) all being knock limited during the test.
They were able to make 80 octane fuel perform as well as 100 octane fuel, and their dyno ran out of capacity because the engine was "permitted" to make so much power before they were able to investigate more extreme water/fuel ratios.
Figure 6 (mentioned on the other thread) was testing done with constant near atmospheric pressure. Small increased in IMEP resulted when water was injected, but the authors noted was the result of greater air mass inducted (as the result of charge cooling?).
regards,
Dan T