author=MileHigh link=topic=16589.msg486023#msg486023 date=1465446170]


MileHigh

I am assuming that you are only discussing the air intake/exhaust, but you are not discussing the combustion chamber resonance.  Is that correct?

It is the expanding and contracting gases in the combustion chamber that is the source for the inlet and exhaust resonant effects.

The simple fact of the matter is that the combustion chamber resonance is essentially the same thing as the striking of a tuning fork resonance.

http://overunity.com/8341/joule-thief-101/510/#.V1kJ69R95kg
Quote post 514--No, an ICE doesn't resonate in any way, shape or form whatsoever.
post 519-same thread---It's all moot because we are not talking about ICEs except to state that they have nothing to do with resonance.
post 523--same thread--Do you get that?  There is true mechanical resonance and it has nothing whatsoever to do with tuning a gas engine and the operating parameters of an engine.
post 540--Presumably the engine operates better, the timing is better, the gasses move in and out of the cylinders more efficiently - but that is NOT RESONANCE like a wine glass resonates by a long shot.
post 544--Your lack of use of language or your abuse of language is ridiculous sometimes.  And the fact still remains that we are not talking about an ICE and none of what you are saying about an ICE meets the scientific definition of resonance.

And so on
Are you now changing your mind MH,and saying that an ICEs combustion chamber resonates like you think a tuning fork dose?.

Since you refuse to accept that a struck tuning fork is resonating, then you are screwed because you have been saying the whole time that there is resonance in the combustion chamber of a cylinder.

No i have not. The combustion process is what gives rise to the resonant systems around the ICE--E.G the exhaust and inlet resonant systems,and so the the combustion chambers actions are in resonance with the inlet and exhaust resonant systems.

What you say above is just a word salad in a desperate attempt to massage the meaning to fit into your definition of resonance.  The air intake is a one-shot Helmholtz resonator that has a time constant associated with it.

That is correct,and that time constant must be in tune with the combustion chambers actions before it will resonate. At the correct RPM,the intake resonator and combustion chamber reach a resonant state,and the intake resonator will begin to resonate.
Why do you not understand how this works,and why the inlet and exhaust chambers are called !resonant! chambers?.

You have a fixed time constant where the engine designers find the best compromise timing to match with the variable cycle frequency of the engine.

And here you have answered half of your question on your own,but yet do not understand as to how or why it is called a resonator,and how it is able to resonate.

Your statements are bull crap, see what I say above.  The speed of the engine is variable so what you are saying does not make sense.

Quote post 531 on the JT thread
Quote:--Indeed, for just about any gas engine there is a power band. It's maximum horsepower out vs. engine RPM.

MH
I would suggest at this point in time,that you go and study how these resonant systems work around the ICE. The two stroke engine would be your best starting point. Learn why the exhaust expansion chamber resonates,learn when it will resonate,and learn as to how this effects the engines output power and efficiency. You will then not make a statement like quoted above,and them claim my statements are bullcrap,as the engine has a wide rev range.

I am at a loss as to why this is so hard for you to understand.
First this-->The speed of the engine is variable so what you are saying does not make sense
Then this-->Indeed, for just about any gas engine there is a power band. It's maximum horsepower out vs. engine RPM

The power band is the RPM range where the resonant systems kick in,and maximum HP is delivered--The very same as reaching the correct frequency of input pulses into a tank circuit,where that tank circuit go's into resonance,and maximum amplitude is gained.
How can you not associate this action with a simple tank circuit?.
The cylinder/piston combo is your inductor,the exhaust expansion chamber is your capacitor,and the explosions of fuel inside the cylinder are your input pulses of energy. When the correct frequency of these explosions is reached,then the system(cylinder/piston,and expansion chamber)go into resonance,where maximum amplitude is reached--maximum HP output is gained.In most high performance two stroke engines,this resonant frequency can be 200 to 300 RPM wide,unlike your electrical tank circuit,which will have a much more definitive frequency range in order to be in the resonant frequency range.

So that's two strikes Brad.  If you are going to stick to your nonsense then you are just back in brain fry territory.

MH
Unfortunately the brainfry is once again on you,due to your lack of understanding about how resonant systems work around the ICE.
Post 531 on the JT thread--Quote: The point being that it is a sweet spot and not "resonance" in the engineering mechanical or electrical sense.
Im sorry MH,but that !!sweet spot!! is at the resonant frequency of the resonant systems around the ICE.

The best thing you could do is admit that you are wrong, and admit that there are two perfectly good definitions for resonance and not just one.  Then all of your statements about the ICE will not be self-contradictory and they will make sense.

First of all,none of my statements about the ICE are contradictory,nor will you find any that are.
Second,you will note that no resonance at all will happen without there being an input energy pulse at the correct frequency acting upon the resonator.

MH
You really do need to get your self sorted out,and understand things before posting rubbish,such as you just did here.


Brad

=MileHigh link=topic=16589.msg486032#msg486032 date=1465466286]




MileHigh

So you have gone into full brain fry mode and are asking me if I am "now changing my mind?"  The combustion chamber resonance process was always an impulse-initiated process, even if I never explicitly used a tuning fork as an analogy for it.  You are back in the bloody Twilight Zone Brad.  Stating for the 76th time that I got it wrong about the resonance and ICE business is just more of the sizzling brain fry.

It's nothing like that MH,and you know i am quoting the truth--they are your quote's.
First you argue with myself and others,that there is no resonance what so ever associated with an ICE,and now your trying to justify your resonance theory by saying that the resonance in the combustion chamber is the same thing as a tuning fork resonating.
It is very clear how you go against your own beliefs when the need to be correct kicks in for you.
It is clear as day,that on one thread you claim that there is no resonance what so ever associated with an ICE,and now,here in this thread,you seem to think the combustion chamber is resonating like a tuning fork-->what planet are you on?

Now you are getting all scrambled up and mushing everything together into one description.  The combustion process is responsible for the resonance in the combustion chamber itself after ignition.  The moving piston that draws air in and pushes the exhaust gasses out cause the Helmholtz resonator processes for the air inlet and exhaust gas outlet.  That's three separate and distinct resonance processes.

Im getting scrambled up . Your the one changing his mind about resonant systems around an ICE to suit his needs--not me. I tried to tell you about resonant systems associated with ICEs,but you denied it left,right,and center,and called me all sorts of names under the sun. But now--now you want to use this !combustion chamber! resonance to try and justify your resonance claim,by saying that this resonance in the combustion chamber is like that of a tuning fork.
Get serious MH

But there is no such thing as a "correct RPM" for an engine, the RPM is also variable.

MH--you have much to learn.
To give you an example. The 1990 Honda CR 250 in stock trim would punch out 49HP  between 7900RPM,and 8600RPM. This is the correct RPM for maximum power.

Yes they are called resonant chambers, but they have nothing to do with your narrow-minded and restricted personal definition of resonance.  Likewise the anti-resonant system in the cylinder itself that kicks in after the gas vapor explosion has nothing to do with your narrow-minded and restricted personal definition of resonance.  And that is the key point.

They work exactly the same as my resonance description,where the driving force pulses are at the correct frequency to the resonant chambers natural frequency.
Your confusion here lies in the fact that you really have no idea as to how there could be such a wide RPM range where this resonance can exist,as you think everything has a very specific resonant frequency.
Go and do some research MH,and see if you can work out how there can exist such a wide frequency range for such resonant systems around the ICE.

Yes I agree that there will be a power band where the resonant systems for the air inlet and exhaust outlet kicks in.  And the reason that there is a power band is because the cylinder drawing air in and then the valve closing is kind of like a "ping" or impulse event when the closed valve causes the inlet air to suddenly redirect to the Helmholtz resonator chamber.  A similar process takes place on the exhaust gas outlet side although I think it's a stretch to call that one resonance.

MH,you are all over the place with rag doll descriptions and fumblings--you need to go and do some research if you wish to play ICEs.
First up,it is the exhaust that dose most of the efficiency increases through resonance--not the inlet. The inlet side of things has very little to do with power increases in ICEs,especially in four stroke engines. Some two stroke engines made use of the Helmholtz resonator chamber effect,and this was called the energy induction system-or EIS. This was used mainly by yamaha,on all there DT and IT range bikes.

But here is the key point:  The air inlet and exhaust gas outlet resonance processes are initiated by what can loosely be called a ping or impulse event.  So that means the resonance effect has nothing to do with the engine RPM, but more importantly the resonance effect has nothing to do with your narrow-minded and restricted personal definition of resonance at all.

It is funny you say that there needs to be a !ping! or !impulse event to causes this resonance effect--seems to be exactly what i am saying,where there needs to be a continual input pulse of energy into the resonator in order for it to resonate. You really do need to go and learn how resonators work on ICEs first,then come back and play shop with me,because ATM,you are just fumbling all over the place.

And again, when the fuel ignition takes place in the cylinder itself, that is absolutely a ping or impulse event, and again that has nothing to do with your narrow-minded and restricted personal definition of resonance.

Isnt it odd that there has to be this ignition of fuel(energy) for every one of your !pings! to take place. How many pings would there be without this ignition of fuel(energy)?.

So in very general terms, we can say that all three resonance effects in the ICE are initiated by discrete ping or impulse events.  That is akin to striking a wine glass or striking a tuning fork. 

MH-you are that messed up,that it's not even funny.
The resonant frequency of the exhaust when that resonator is resonating,is exactly the same as the engine RPM-for every single ping--there is a pong out the exhaust
You can measure the engine RPM of a two stroke,using a microphone near the exhaust,and a scope. The frequency shown on the scope will be your engine RPM.

That is why there are resonance effects over a range of engine RPMs, they are all initiated by ping-like events and have nothing to do with the engine RPM, and they have nothing to do with your definition of resonance at all.

You are a funny man MH--your good for a laugh at least lol.
As i said above,engine RPM is directly related to the frequency at the exhaust resonant chamber.
Like i said,you need to go and do some research on why this resonance can be maintained over a wide range of RPMs,and that resonance will be at the same frequency as the engine RPM

So you are up a creek without a paddle.

No MH--you have fell in the creek,and drowned.
If you want to talk ICEs with me,then go and learn something about how all these systems work first--then we can talk shop.

Really?  Well for starters Brad like I said you can't just mush three separate and distinct types of resonance events all into one general statement.

All three effects come into play at the same time,and this gives rise to the resonant systems around the ICE at given RPMs--the power band.

 

That makes no sense at all.  Break it down into three separate things and let's see how you do identifying the mathematical model for each one.

MH
It is clearly evident that it is you that needs to go and do some learning--i have been doing it for over 35 years now,and i do know what i am talking about when it comes to resonant effects around high performance engines,as this is my life.
Start with the 2 stroke engine MH,as this would be the easiest for you to understand,as most of the work is done by the exhaust expansion chamber.
Start there,and you will then see how there can be such a wide rev range,while being able to maintain resonance between the exhaust resonance chamber,and the cycles of the engine.

Read above and see how it is your lack of understanding.

The fact that you do not understand as to how the rev range can vary so much,while still maintaining resonance,is a clear indication that you need some education on how these resonant systems work around the ICE.

None of them would be contradictory if you could bring yourself to admit that the resonance effects in the ICE are initiated by ping events and in that sense there are essentially the same as saying that a tuning fork resonates when you strike it.

MH,there is only one ping event for every cycle(every vibration) of the resonant chamber,and that one ping event is the ignition of the gas mix inside the cylinder. As soon as the gas mix is stopped from igniting,there is no more resonance from the resonance chamber--no ping,no resonance.

So are you going to get real and simply admit that your narrow-minded and restricted definition of resonance was wrong or are you just going to sizzle and steam off into the sunset?

Not likely MH,as it is clear from your post,that you have no idea as to what you are talking about.
First go and learn as to how resonance can be maintain over a wide rang of RPM with a 2 stroke engine,then we can talk shop.Once you have done that,then your questions will start to answer them self,but i will be here in case you get stuck.


Brad

Brad:

For starters enough of the insanity about challenging me on "being a new convert" to ICE resonance.  When you showed me the right information I admitted that I was wrong right away and that was months ago.  So why are you saying ridiculous things like "First you argue with myself and others,that there is no resonance what so ever associated with an ICE,and now your trying to justify your resonance theory by saying that the resonance in the combustion chamber is the same thing as a tuning fork resonating."

Why are you ridiculously spinning like this?  I also edited my previous posting to state that it's a bit of a stretch to model the combustion chamber resonance like striking a tuning fork, that's too simple.  It's more of an anti standing wave process, which is really a three-dimensional resonant tuning cavity process.

I fully realize that you have a lifetime's worth of working with engines and you are an expert with them.  But what you don't have is a deeper and fundamental level of insight that a scientific or engineering education can give you.  For example, you could not answer the two questions about the wine glass and you were not even close.  Likewise, you were unable to come up with the simplified equivalent circuit/mathematical model for something as basic as a bell or a tuning fork.  Nor could you visualize in your mind how they resonate.

Like it or not, even though the engine has an RPM range where the resonance effects are doing their magic and giving you better performance, it is not directly related to the RPM of the engine itself.  Each of the three resonant effects are a ping-like event where the ping initiates a resonant response.  That is loosely comparable to striking a tuning fork.

Like it or not, your personal definition for resonance does not apply, because the resonance effects in the ICE are not directly tied into the engine RPM acting as a periodic stimulus resulting in an enhanced resonant response from the resonating element.

They work exactly the same as my resonance description,where the driving force pulses are at the correct frequency to the resonant chambers natural frequency.

No, absolutely not.  You are back to trying to put a square peg into a round hole because you would nearly have a nervous breakdown to admit that you are wrong.  In this case I am the "little guy" and you are the "big guy" and the little guy is teaching the big guy because the big guy with all of his 35 years of mechanical experience with ICE's, still was unable to identify how a bell can resonate and visualize and create the mathematical model for it.  Like it or not, these are facts.

It's the driving force pulses themselves that elicit the resonant responses in the ICE that cause improved performance in the ICE, and NOT the correct frequency of the driving force pulses.

The resonant chamber frequency in the combustion chamber has nothing to do with the frequency of the driving force pulses due to the engine RPM, nothing.

The one-shot resonant response of the intake Helmholtz resonator will be amenable to a certain frequency range of the driving force pulses due to the engine RPM, but when you really understand what is going on, the two things are actually decoupled from each other.

The one-shot resonant response of the exhaust gas expansion chamber quasi Helmholtz resonator will be amenable to a certain frequency range of the driving force pulses due to the engine RPM, but when you really understand what is going on, the two things are decoupled from each other.

So your narrow-minded definition of resonance does not apply to the ICE, even though an ICE will operate better through some forms of resonance.

First go and learn as to how resonance can be maintain over a wide rang of RPM with a 2 stroke engine

I understand that as clear as a bell.

So one more time, all of your problems will go away if you can simply admit the following is true and there are two definitions for resonance:

A tuning fork is an acoustic resonator in the form of a two-pronged fork ... It resonates at a specific constant pitch when set vibrating by striking it against a surface ...

The little guy is talking, and if you were wise you would listen.  You will not have a nervous breakdown if you admit that you were wrong with the limited definition of resonance that you are currently stuck to like a fly on flypaper.

MileHigh

Brad:



Look at this clip, you will see an amazing ping-initiated RESONATOR in action that actually has a resonant frequency that is a function of time.  Talk about a mind blowing brain bender, eh?  A resonant frequency that changes in time?  Go check the rule books.

https://www.youtube.com/watch?v=TXxVA2idyL0

It's not a bloody "natural frequencyerator," it's a bloody RESONATOR.

MileHigh

Don't be an old dog, you can learn some new tricks.

MH,i am not the one that needs to learn here,in regards to the resonant effects surrounding an ICE.

Talk about a mind blowing brain bender, eh?  A resonant frequency that changes in time?  Go check the rule books.

If you are saying that a resonant frequency cannot change in time in regards to the ICE issue we are discussing,then you had better go and do some research,and begin to understand how the resonant chamber on the exhaust of the 2 stroke ICE can indeed change with time,and why the resonance can continue over a wide range or RPM.

If you do not think that the resonant frequency of the expansion chamber can change,without physically changing the shape of the resonant chamber,then you do have much to learn.
I can tell you in one short post how this is achieved,but you need to do some learning of your own.

If you change the density of the magnetic material of the core of an inductor,while maintaining the physical size of that inductor,will the resonant frequency of that inductor change?


Brad

If you are saying that a resonant frequency cannot change in time in regards to the ICE issue we are discussing,then you had better go and do some research,and begin to understand how the resonant chamber on the exhaust of the 2 stroke ICE can indeed change with time,and why the resonance can continue over a wide range or RPM.

If you do not think that the resonant frequency of the expansion chamber can change,without physically changing the shape of the resonant chamber,then you do have much to learn.
I can tell you in one short post how this is achieved,but you need to do some learning of your own.

If you change the density of the magnetic material of the core of an inductor,while maintaining the physical size of that inductor,will the resonant frequency of that inductor change?

Brad

I am not going to look anything up, but I think in some engines they simply change the length of the exhaust expansion chamber to match the engine RPM.  That's to ensure a synchronicity between the piston pulse rate to empty the exhaust gasses and the tuned expansion chamber helping suck the exhaust gasses out of the cylinder, but it is not resonance.  It might be called a tuned exhaust port or a variable tuned exhaust port or something like that but it is not resonance.

If you change the density of the magnetic material of the core of an inductor,while maintaining the physical size of that inductor,will the resonant frequency of that inductor change?

I know what you are trying to say but it's still bloody annoying because we are primarily discussing electronics and inductors do not resonate all by themselves.

For starters, you are going to have to have the intellectual capacity to make a distinction between "motor shop talk resonance" and the resonance we have been discussing this whole time.  So this sentence, "the way i define resonance is exactly how the resonant systems around the ICE work" is an absolute non-starter.

Like it or not, resonance is the exchange of energy back and forth in a system between two forms.  Typical examples would be between a capacitor and an an inductor, or a moving mass and a spring.  Of course, what I just said is something you are currently completely blind to for some strange and inexplicable reason.  You want to insist that resonance is just the observation of an increased response of a resonant system to an external stimulus at the resonant frequency.  That is an acceptable second definition for resonance, but to claim that it is the only definition like you are insisting is completely and totally ridiculous.

And now it would seem you want to "squeeze in" a new definition for resonance, which is some kind of "motor shop talk resonance" which has nothing to do with an energy exchange back and forth between two components like a moving mass and a spring, and that simply will not fly and is totally unacceptable.

NO, when there is an explosion in the cylinder, that impulse of energy sets up a resonant standing wave pattern inside the cylinder cavity that is deemed undesirable, and so a secondary resonant cavity is set up in the cylinder to counteract that.  That standing wave resonance will happen at its own unique frequency.  That is in no way, shape or form, "resonating at the same frequency of the explosion."

No resonance is not an interaction between the two.  The explosion initiates a separate and distinct resonant standing wave in the cylinder cavity.  The resonance is the resonance in the cavity itself, and not the explosion.

Moving on to the Helmholtz resonators, they just respond to an impulse stimulus and that's it.  The frequency of the stimulus is irrelevant.  The "resonance like" effect in the Helmholtz resonator is that gasses rush into the resonator chamber, and that is a moving mass.  Then the chamber itself acts like a spring.  That is the resonance - moving air as a moving mass and air in the chamber acting like a spring.  That has nothing whatsoever to do with the impulse that initiated the event or the frequency of the impulse that initiated the event.

Note also that there is not really any cycling back and forth of the same energy as you have in true resonance.  It's a one-shot process, kinetic energy goes in, gets stored temporally as potential energy, and then the air leaves, and then new air rushes into the Helmholtz resonator chamber.  Even though the same energy and same mass is not cycling back and forth like there is in true resonance, the principles at play are essentially the same.

So when you mistakenly talk about the air inlet and the exhaust gas outlet being "in resonance" with the cylinder explosions, then what is it really?  It's certainly not resonance even if the boys in the shop call it "resonance" in their own "shop talk" language.  With respect to the cylinder explosions and the input and output ports, there is no cycling of energy back and forth between two forms so it is not resonance.

Here is what it really is: There is a nice synchronicity between the cylinder explosions and the Helmholtz resonators pushing air into the cylinder and then also sucking exhaust gasses out of the cylinder.  The fact that the cycle times for the Helmholtz resonators line up with the cylinder timing to make gas move into and out of the cylinder more efficiently is great but it is not resonance.  The resonance is in the Helmholtz resonators themselves.  What it really is is the Helmholtz resonators act as timing elements in the operation of the engine to ensure that the engine runs synchronously.

Here is the synchronous operation of the engine as a sequence of timing events one after the other:  1) push air into the cylinder, 2) explosion, 3) suck exhaust gasses out of the cylinder.  This is a nice advantageous synchronous operation facilitated by the actions of the Helmholtz resonators that makes the engine run better but it is not resonance.  There is no resonant cycling of energy back and forth in two forms in steps 1, 2, and 3 which is the true signature for resonance.

All that being said, if you would just accept that a tuning fork resonates, then you could accept that the Helmholtz resonators resonate all by themselves without having anything to do with the cylinder explosions and then you would be fine.

MileHigh

It's like i said MH--you need to further your understanding on how the resonant systems around an ICE work.
The 2 stroke engine is your best starting point.

I see from one of your comments that  you do not understand that some of the charge expended into the exhaust resonant chamber,actually returns back into the cylinder.

You do need to brush up on ICEs MH.


Brad

I am not going to look anything up, but I think in some engines they simply change the length of the exhaust expansion chamber to match the engine RPM.  That's to ensure a synchronicity between the piston pulse rate to empty the exhaust gasses and the tuned expansion chamber helping suck the exhaust gasses out of the cylinder, but it is not resonance.  It might be called a tuned exhaust port or a variable tuned exhaust port or something like that but it is not resonance.

I know what you are trying to say but it's still bloody annoying because we are primarily discussing electronics and inductors do not resonate all by themselves.

" inductors do not resonate all by themselves."

Actually they do.  Inductors do have capacitance no matter how small. Ive done these tests along with bifi comparisons where the increased capacitance lowers the freq of resonance compared to a normal wound inductor.

Mags

If you change the density of the magnetic material of the core of an inductor,while maintaining the physical size of that inductor,will the resonant frequency of that inductor change?

Modified using good practices:

If you change the permeability of the magnetic material of the core of an inductor, while maintaining the physical size of that inductor, will the resonant frequency of an LC circuit made with that inductor change?

Interestingly, actually increasing the density of the core (e.g. by compressing it with sound waves) changes the permeability of the core.  This is known as the Villari effect.