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Laminar flow discussion

This is a discussion on Laminar flow discussion within the Veloster Performance forums, part of the Veloster Turbo Garage category; Originally Posted by Gaijiin I have spent the morning talking with CERMA John on this matter. He illuminated several mis-conceptions and pointed out many of ...

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    Quote Originally Posted by Gaijiin View Post
    I have spent the morning talking with CERMA John on this matter. He illuminated several mis-conceptions and pointed out many of the things you've illustrated about Turbo's preferring to DRAW from cooled lower pressure air. vs higher pressure Laminar flow.

    -He also gave me some ideas/principles on making that "low" pressure drop..,-- TANK, we will call it.

    So far Im gleaning it is ideal:

    - For high pressure Laminar flow air to rush in, be constricted slightly, then experience a pressure drop.
    - This same area of pressure drop JOHN said is ideal for the 90 bend.
    - The bend itself coupled with a dimpled or rough interior and a wide girth causes the good kind of turbulence and acutal temperature reduction.

    He stated the turbines capacity is its wheel setup, that is the controlling factor on how much air. He told me one CAN NOT force air into the turbine. It sucks the air in relative to its fin and speed.

    So under the best case scenario my intake will.
    -Drop the pressure of the air in the draw tank relative to the incoming Laminar flow at the cone.

    This is cool.
    Time and experimentation will tell.
    Guess I can come up with a system and head to head it with the Godzilla which is just big ole smooth piping and massive air cone. LOL!!!
    For any intake you almost always want to have the coolest, highest pressure air entering possible, in order to make the most power.
    The tank you're referring to is called an intake plenum or anti-surge tank. They work well if implemented properly. Some cars have them and some do not. Most if not all do not have one large enough as the focus is emissions and economy not performance or raw power. The VT has one on the intake mani under pressure and the other in the form of the oem airbox.
    The larger diameter upper intakes out there act as if a surge tank were on a smaller intake pipe, yet are one big smooth flowing pipe. This has low pressure drop/higher pressure in the pipe, thus why you would have the best throttle response and power from the larger pipe. Having a surge tank on an already large piping should further help with pressure drop.
    You ideally want pressurized air entering the surge area to help fill the volume as quickly as possible. This can all be accomplished, but takes a lot of work, knowledge, and testing. Not as easy as throwing something together and done.
    RE the 90, bends are not ideal anywhere, especially in area of low pressure. Higher pressure will help air flow through the pipes where restrictions are, such as a bend or smaller diameters.
    Also a slightly rough surface creates a boundary layer of air in the pipe, decreasing resistance to flow, thus enabling more flow. Temperature reductions are also possible however difficult to measure or prove.
    Also the limiting factor of air through the turbo itself is the area it has to pass between the comp wheel fins and the comp housing. And you can force air through this area and does not have to be drawn through.
    My experience in turbos has been in setups that have flowed 60lb/min on the low end to well over 200lb/min on the high end. Same concepts apply to our setup, just in smaller forms.

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    Quote Originally Posted by trdtoy View Post
    For any intake you almost always want to have the coolest, highest pressure air entering possible, in order to make the most power.
    The tank you're referring to is called an intake plenum or anti-surge tank. They work well if implemented properly. Some cars have them and some do not. Most if not all do not have one large enough as the focus is emissions and economy not performance or raw power. The VT has one on the intake mani under pressure and the other in the form of the oem airbox.
    The larger diameter upper intakes out there act as if a surge tank were on a smaller intake pipe, yet are one big smooth flowing pipe. This has low pressure drop/higher pressure in the pipe, thus why you would have the best throttle response and power from the larger pipe. Having a surge tank on an already large piping should further help with pressure drop.
    You ideally want pressurized air entering the surge area to help fill the volume as quickly as possible. This can all be accomplished, but takes a lot of work, knowledge, and testing. Not as easy as throwing something together and done.
    RE the 90, bends are not ideal anywhere, especially in area of low pressure. Higher pressure will help air flow through the pipes where restrictions are, such as a bend or smaller diameters.
    Also a slightly rough surface creates a boundary layer of air in the pipe, decreasing resistance to flow, thus enabling more flow. Temperature reductions are also possible however difficult to measure or prove.
    Also the limiting factor of air through the turbo itself is the area it has to pass between the comp wheel fins and the comp housing. And you can force air through this area and does not have to be drawn through.
    My experience in turbos has been in setups that have flowed 60lb/min on the low end to well over 200lb/min on the high end. Same concepts apply to our setup, just in smaller forms.
    I already have a prototype for the bend, its a full 6 inch 90. I'm going to give it a thin skim cote of pure coldweld epoxy on the inside. I will let it cure until its just tack free but still malleable. Then I am goin to roll a golf ball over all the internal surface and get the same finish to get the "good turbulence" benefit.
    Last edited by Gaijiin; 11-02-2015 at 06:12 PM.
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    Very cool read.. I learn a bit tonight from that. Where the hell were you on all the debate on The SRI VS CAI for turbo cars?!?
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    With a 6" 90° you will not need to do anything to it as other areas in the system will likely be more restrictive. Also there are better ways of accomplishing what you are going for than what you have planned for the 90 bend in question. Either way you will be splitting hairs and likely wasting your time/effort in that area.....

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    Quote Originally Posted by Gaijiin View Post
    I have spent the morning talking with CERMA John on this matter. He illuminated several mis-conceptions and pointed out many of the things you've illustrated about Turbo's preferring to DRAW from cooled lower pressure air. vs higher pressure Laminar flow.

    -He also gave me some ideas/principles on making that "low" pressure drop..,-- TANK, we will call it.

    So far Im gleaning it is ideal:

    - For high pressure Laminar flow air to rush in, be constricted slightly, then experience a pressure drop.
    - This same area of pressure drop JOHN said is ideal for the 90 bend.
    - The bend itself coupled with a dimpled or rough interior and a wide girth causes the good kind of turbulence and acutal temperature reduction.

    He stated the turbines capacity is its wheel setup, that is the controlling factor on how much air. He told me one CAN NOT force air into the turbine. It sucks the air in relative to its fin and speed.

    So under the best case scenario my intake will.
    -Drop the pressure of the air in the draw tank relative to the incoming Laminar flow at the cone.

    This is cool.
    Time and experimentation will tell.
    Guess I can come up with a system and head to head it with the Godzilla which is just big ole smooth piping and massive air cone. LOL!!!
    Gosh I don't even know where to start lol

    For high pressure Laminar flow air to rush in, be constricted slightly, then experience a pressure drop.
    Not sure what you mean here. It is my understanding that air would be very turbulent as it hits and enters the air filter (coming from all directions as the car passes through space).
    A velocity stack in the filter would help straighten it out, but without running the numbers I bet we are still very turbulent.
    Also, just to reiterate there is already the existance of pressure a drop of a certain number based on the intake system, because the very definition of fluid flow is a difference in pressure from one side to the other.

    The bend itself coupled with a dimpled or rough interior and a wide girth causes the good kind of turbulence and acutal temperature reduction.
    I don't really think turbulence is bad at all in our situation. We will probably always have turbulent flow in the entire system.
    We need to focus on parts and their geometry to keep pressure drop to a minimum.

    Minimum pressure drop on the intake side optimizes compressor efficiency and minimum pressure drop on the boost side means we get the most pressure into the engine.

    He stated the turbines capacity is its wheel setup, that is the controlling factor on how much air. He told me one CAN NOT force air into the turbine. It sucks the air in relative to its fin and speed.
    I hope this is a misunderstanding, because my knowledge on the subject suggests the opposite of this!

    The exhaust gases from the engine drive the turbine wheel. Since the turbine wheel is spinning and connected to the compressor wheel, the compressor wheel sucks the intake air in.
    Never have I heard or read that the turbine wheel sucks the air out of the engine. When the higher pressure and temperature exhaust gases enter the turbine housing and interact with the turbine wheel, the expansion of the gases in here is what drives the turbine wheel. I have paraphrased from here: https://turbobygarrett.com/turbobygarrett/basic

    The A/R (or Area/Radius) characteristic of the turbine housing is what determines the performance of the turbine. If you take two engines with the same turbo:
    - The smaller A/R housing has better boost response and mid-range power.
    - The larger A/R housing has worse spool but has much better top end power.

    Again, paraphrased from here: https://turbobygarrett.com/turbobyga...housing_sizing

    Quote Originally Posted by trdtoy View Post
    For any intake you almost always want to have the coolest, highest pressure air entering possible, in order to make the most power.
    The tank you're referring to is called an intake plenum or anti-surge tank. They work well if implemented properly. Some cars have them and some do not. Most if not all do not have one large enough as the focus is emissions and economy not performance or raw power. The VT has one on the intake mani under pressure and the other in the form of the oem airbox.
    The larger diameter upper intakes out there act as if a surge tank were on a smaller intake pipe, yet are one big smooth flowing pipe. This has low pressure drop/higher pressure in the pipe, thus why you would have the best throttle response and power from the larger pipe. Having a surge tank on an already large piping should further help with pressure drop.
    You ideally want pressurized air entering the surge area to help fill the volume as quickly as possible. This can all be accomplished, but takes a lot of work, knowledge, and testing. Not as easy as throwing something together and done.
    RE the 90, bends are not ideal anywhere, especially in area of low pressure. Higher pressure will help air flow through the pipes where restrictions are, such as a bend or smaller diameters.
    Also a slightly rough surface creates a boundary layer of air in the pipe, decreasing resistance to flow, thus enabling more flow. Temperature reductions are also possible however difficult to measure or prove.
    Also the limiting factor of air through the turbo itself is the area it has to pass between the comp wheel fins and the comp housing. And you can force air through this area and does not have to be drawn through.
    My experience in turbos has been in setups that have flowed 60lb/min on the low end to well over 200lb/min on the high end. Same concepts apply to our setup, just in smaller forms.
    Gonna try to discuss this one by one too lol

    The tank you're referring to is called an intake plenum or anti-surge tank. They work well if implemented properly. Some cars have them and some do not. Most if not all do not have one large enough as the focus is emissions and economy not performance or raw power. The VT has one on the intake mani under pressure and the other in the form of the oem airbox.
    Can you post some pics or links to these for other cars? I am not familiar with the parts and how they are used to make power.

    This has low pressure drop/higher pressure in the pipe, thus why you would have the best throttle response and power from the larger pipe. Having a surge tank on an already large piping should further help with pressure drop.
    You ideally want pressurized air entering the surge area to help fill the volume as quickly as possible.
    Forgive me if I am misunderstanding your point, but you can't have air pressure higher than 14.7 psia enter the intake system. That is unless you turbo or supercharge the system and I have no experience with duel charging.
    Is this what you mean by higher pressures need to be in the pipe? Because once the air enters the filter and makes it's way through the pipe, we already have pressure drop/loss from atmospheric pressure outside the system.

    Minimize the pressure drop at the turbo! Air filters do one thing, protect the engine from foreign objects. You won't see any high performance turbo car trying to win a race have an air filter unless they really need it lol

    Also a slightly rough surface creates a boundary layer of air in the pipe, decreasing resistance to flow, thus enabling more flow.
    I might have to ask you to cite a source for this reference or at least define what you mean by "enabling more flow."

    I mentioned earlier that
    Velocity = air flow / area (cross-sectional area of pipe)
    Re-arrange the equation and you get:

    Air Flow = Velocity x Area (cross-sectional area of pipe)

    While I can't directly relate the equations without doing some further referencing of text books, your reference doesn't seem correct.
    I come to the conclusion that pipes with smooth walls would always be the preference, because a rougher pipe creates those boundary layers, and decreases velocity the farther you get from the center of the pipe.
    Rough pipe walls create pressure drop. We don't want pressure drop.

    In some majority of fluid problems I've done, it's recommended to work with the average velocity, and this is calculated using some equations I an't type clearly because they involve some integrals lol
    Average velocity is just that, an average taken from the center of the pipe out to the wall.

    Back to Air Flow = Velocity x Area (cross-sectional area of pipe). What I was trying to point out is, that if you decrease the velocity (due to rough pipe walls slowing fluid flow down), you decrease airflow.

    Again, please correct me if I am wrong
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    RE anti-surge tanks on cars just look at any oem airbox. It houses the filter but also serves as one of these. Additionally they may also have a plastic or aluminum intake mani with runners and an additional shared volume area which is also there for the same reasons. For the high hp stuff an online search of custom intake manifolds will show you plenty or take a trip to your local dragstrip and you may see a few nice ones.

    By air pressure in the intake I'm referring to having the most possible wether it be above or below ambient pressure. Above ambient pressure is possible by supercharger or a turbo however I was referring to functional ram air from ducting that feeds the system from an open inlet facing oncoming air flow. Same concept of the dragster with the tall hood intake creating a supercharging effect in their intake manifolds. We are not talking huge pressures as Iirc the equation is something like mph x mph x .0000176 = psi. Or .176 psi at 100 mph. Not much but beats having vac in the system. I have confirmed this functional ram air effect across several platforms.

    Pipe surface and air flow..... years ago I stood beside a gentleman that made custom intakes, manifolds, head work, etc and flow tested everything. He was telling me that a slightly rough surface will flow more than a smooth one. Told him to prove it as i was in disbelief. He then proceeded to show me what a pipe would flow that was smooth inside. Then he buffed with fine sand paper and flow tested again. To my surprise it indeed flowed more. But then he buffed using larger grit paper and the flow fell off. It had like a bell curve effect on the flow. The way he explained it to me the boundary air on the walls had to create micro sized eddies (fine grit)so the rest of the air in the pipe could slip over them and not be in contact with the walls thus slightly speeding up flow. Make the Eddies too large(coarse grit) and they will make air too turbulent and disrupt flow slowing it down.
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    Quote Originally Posted by trdtoy View Post
    Pipe surface and air flow..... years ago I stood beside a gentleman that made custom intakes, manifolds, head work, etc and flow tested everything. He was telling me that a slightly rough surface will flow more than a smooth one. Told him to prove it as i was in disbelief. He then proceeded to show me what a pipe would flow that was smooth inside. Then he buffed with fine sand paper and flow tested again. To my surprise it indeed flowed more. But then he buffed using larger grit paper and the flow fell off. It had like a bell curve effect on the flow. The way he explained it to me the boundary air on the walls had to create micro sized eddies (fine grit)so the rest of the air in the pipe could slip over them and not be in contact with the walls thus slightly speeding up flow. Make the Eddies too large(coarse grit) and they will make air too turbulent and disrupt flow slowing it down.
    And that is why golf balls are shaped the way that they are, the alter the boundary air. However just denting the surface will not create the same effect, there is (as noted above) an optimal depth/size/distribution. With the sandpaper technique there is even an optimal direction for the sanding whorls.
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    Yes he had a technique to the sanding as well that worked better, perpendicular to flow.....
    Also the golf ball dimple effect does not work the same in an enclosed pipe as it does in open air environment.
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    Thanks for the continued input 6. Maybe I wasnt clear:

    We are in agreement.

    (The exhaust gases from the engine drive the turbine wheel. Since the turbine wheel is spinning and connected to the compressor wheel, the compressor wheel sucks the intake air in.)

    This observation relative to the positioning of the larger "lower pressure" tank or plenum. What John was telling me must hold water, I have viewed several examples from the Honda world.
    -Power chambers
    -Top fuel power chambers from Acuras.

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    Quote Originally Posted by trdtoy View Post
    Yes he had a technique to the sanding as well that worked better, perpendicular to flow.....
    Also the golf ball dimple effect does not work the same in an enclosed pipe as it does in open air environment.
    The general concept does apply as it relates to the flow of a fluid medium, I.E.: the boundary layer, however the specifics of an object through said medium vs the dynamics of a specific volume through a chamber... yes totally different ball game.
    - Jon

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