Just last week i ran into the guy that owns a brake muffler shop that does most of the work on our vehicles...i told him i'll be coming in soon for a new exhaust system, told him i was thinking bout going straight pipe. He knows that we carry a slide in camper and he says, "well, no, you dont want to straight pipe it cause if your carrying a camper your gonna NEED that back pressure"
not knowing WHAT the heck he was talking about i nodded knowingly and agreed. :
I think i'll just go to a different shop!

 

[quote author=Mudinford link=board=7;threadid=22079;start=0#msg206580 date=1068148031]
Here is a thought...can some mufflers flow even better then a straight pipe? They do have baffles cut in a spiral pattern and i would spinning the exhaust (far enough away from the turbo) would cause a scavenging affect.....thus pulling exhaust out of the pipe? Theory of putting a spin on water going through a funnel. It will go through faster with a rotation rather than none. Ponder that!
[/quote]


this is what an aero turbine muffler claims to do. By creating a vacume effect. www.aero-turbine.com

 

[quote author=kdawg62 link=board=7;threadid=22079;start=15#msg206877 date=1068189675]
this is what an aero turbine muffler claims to do. By creating a vacume effect. www.aero-turbine.com
[/quote]

The theory behind the aero-turbine VIOLATES the first two laws of thermodynamics!

First Law of Thermodynamics: Energy can be changed from one form to another, but it cannot be created or destroyed. The total amount of energy and matter in the Universe remains constant, merely changing from one form to another. The First Law of Thermodynamics (Conservation) states that energy is always conserved; it cannot be created or destroyed. In essence, energy can be converted from one form into another.

The Second Law of Thermodynamics states "in all energy exchanges, if no energy enters or leaves the system, the potential energy of the state will always be less than that of the initial state." This is also commonly referred to as entropy.


The only way you can produce a vacuum at the turbine outlet is if you wrap your lips around your tailpipe and suck on it. :P

A venturi is designed to create a low-pressure area at and only at the throat of the venturi. A venturi depends on a change in velocity of the moving fluid passing through it.

In order for a fluid to move there MUST be a pressure difference. In an exhaust system the tail pipe is the place of lowest pressure with reference to the rest of the system.

 

Turbines require a change in enthalpy to operate.

Enthalpy is basically a measure of a fluids ability to do work. Wf+U, or pressure +temperature.

The higher the temperature and pressure differential across a turbine, the more work the turbine will do, provided you can get the exhaust gases out of the way fast enough. If the exhaust gases are cooled too much by an over sized exhaust system, turbine performance WILL suffer.

Hot gases move easier than cold gases. Molecular collisions between hot gas molecules are more elastic than those of cold molecules. As previously stated, it is possible for an exhaust system to be too big, and the gases can stagnate and cool off.

You must keep the exhaust gases hot and moving!

 

Diesel Freak, 100% correct. ANY and ALL backpressure AFTER the turbo is BAD BAD BAD. You are talking about a turbine which as you said, is a delta enthalpy machine. The more delta h, the better. You can get more delta by increasing the inlet temperature and/or pressure or by decreasing the exit temperature and/or pressure. This is why you guys should all be coating and insulating your exhaust manifiolds. The hot exhaust gasses leave the cylinder head with lots of juicy delicious enthalpy, KEEP IT IN THERE until it can do its work in the turbine, not heat up the underneath of the hood...



Zino

 

Zino,

Juicy???

 

Diesel Freak, take two big bottles of water, turn them both upside down. Let one empty by itself, but swirl the other one. When you're done tell me which one empties faster.

 

Any fluid moving in a straight line is going to empty the bottle faster. Remember the shortest distance between your girlfriends house and yours is a straight line. Swirling gas, water, air, etc. moves a longer distance than air in a straight line.

The same as taking the long way around to get to your girlfriends house. Not cutting through alleyways, across parking lots, etc.

The only time you could get to her house faster going the long way is to increase the speed at which you travel. Maybe a moped or something VS walking.

Unfortunantly, its hard to speed the exhaust gas up any after its leaves the turbine housing and passes through the downpipe. The temperature has dropped a good bit from expansion.

Don~

 

[quote author=Willyzao link=board=7;threadid=22079;start=15#msg207079 date=1068236749]
Diesel Freak, take two big bottles of water, turn them both upside down. Let one empty by itself, but swirl the other one. When you're done tell me which one empties faster.
[/quote]

what does this have to do with this thread? the system dynamics are not even related.

One has to do with hot gas under pressure escaping through a pipe, and the other has to do with a liquid that is draining from a bottle where air has to enter from the same opening to displace the volume left by the escaping liquid.

ok, I will play your game.

take two Styrofoam cups of water, both have been filled with water from the same kitchen sink, the only difference is that the temperature of the water in each glass is different. One is room temp (taken from the cold side of the tap) the other is Boiling Hot.

Both are then placed in a freezer at 0F at the same time. Which one freezes faster, and WHY?

 

Thanks to DIESEL FREAK!! I have been trying to explain to people why the aero-turbine cannot work as advertised!

As for the freezing water, the boiling water will freeze faster under certain circumstances. Boiling water contains less dissolved gasses, which slow the rate of cooling. Also, boiling water has more evaporation, which is a cooling process. Finally, the evaporation of the boiling water leaves less water to cool, thus the rate at which it will cool is faster.

IF you use a metal-walled container, cold water will freeze first. If you use styrofoam cups, the boiling water will freeze first.

Hohn

 

[quote author=Diesel Freak link=board=7;threadid=22079;start=15#msg207087 date=1068239049]
[quote author=Willyzao link=board=7;threadid=22079;start=15#msg207079 date=1068236749]
Diesel Freak, take two big bottles of water, turn them both upside down. Let one empty by itself, but swirl the other one. When you're done tell me which one empties faster.
[/quote]

what does this have to do with this thread?
[/quote]

Nothing, I just figured a guy with enough time on his hands to quote thermodynamics would have the time to try a little experiment for me.

I don't agree with you that "The theory behind the aero-turbine VIOLATES the first two laws of thermodynamics!". Correct me if I'm wrong, but accelerated exhaust will carry the heat out the end of the pipe as a property of the exhaust (aeroturbine), as opposed to slower moving exhaust dissipating its heat along the length of the pipe. The heat is accounted for in either scenario, no laws have been broken; it all depends on how you draw your box.

A straight line is the fastest way to get some where? Man, why didn't someone tell me that earlier. You know, laminar flow has a higher mean velocity than turbulent flow, so even though it's traveling further, it's traveling faster. Changing turbulence to a spiral flow pattern is your moped.

I don't have an aeroturbine and I don't personally know anyone that runs one. The problem with 'innovations' like these are that the theory makes sense and sounds good (to some people), but in reality they never quite work out. I was watching Spike TV the other day and they dynoed one of those Tornado type things; didn't do a thing, but the advertisement sounds good.

 

A straight line is the fastest way to get some where? Man, why didn't someone tell me that earlier. You know, laminar flow has a higher mean velocity than turbulent flow, so even though it's traveling further, it's traveling faster. Changing turbulence to a spiral flow pattern is your moped.


Laminar is smooth flow. Like a nice smooth river of water. Spiraling flow is not laminar. Laminar flow is a very constant in velocity. Our gas velocity in the pipe changes with only slight throttle changes. Spiraling flow is not a moped because it takes longer for it to reach the destination. Follow a molecule in its path to anywhere and the one that is not traveling in a straight line gets there after the one that is. As long as they both travel the same speed. You cant accelerate the exhaust gas to move any faster unless you shrink the size of the pipe it is traveling through or increase the temperature of the gas.

Don~

 

True, it does depend on how you draw the box, but...

they are blatantly stating that the gases are "working on themselves without any external energy input" to raise their velocity.

to accelerate a gas, a convergent nozzle is employed, and this ends up being a flow restriction which raises upstream pressure in the system.

They are trying to sell perpetual motion, a clear violation of the conservation of energy principle.

as to your experiment, I punched a hole in the bottle I did not swirl...it drained the fastest.

 

[quote author=Diesel Freak link=board=7;threadid=22079;start=15#msg207132 date=1068248137]

they are blatantly stating that the gases are "working on themselves without any external energy input" to raise their velocity.

to accelerate a gas, a convergent nozzle is employed, and this ends up being a flow restriction which raises upstream pressure in the system.

They are trying to sell perpetual motion, a clear violation of the conservation of energy principle.[/quote]

I'll give you that, that's a much better argument. You and Don M sound like good guys to have around the campfire when it's time to start philosophizing. Is that Don M of Don M's EDM injectors? Just curious.

Just for fun: Bullets and footballs spiral. Your toilet flushes by creating a vacuum; to move out of the bowl it starts to swirl. Laminar flow can be fast or slow (subcritical/supercritical).

Have a good weekend guys.

 

Not to pick it apart but bullets and footballs spiral to keep them straight. Not to go faster. The aerodynamics help achieve higher speeds. They do shot bullets out of guns with no rifling and the bullet doesnt spin. And I have a toilet that flushes straight down. No swirling here. I dont understand where this compares to exhaust gases?