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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; Old pic but finished product.. My engine bay looks a bit different now....

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Thread: Laminar flow discussion

  1. #11
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    Old pic but finished product.. My engine bay looks a bit different now.

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    Yup,..you and I believe Mgadar had this setup.

    At this point that unavoidable 90 is going to be accomplished with a full section 90 mandrel bend 4 inch pipe. Unless I figure something else out.

    I actually sourced a full 6 inch 90 mandrel bend.!!!
    Last edited by Gaijiin; 11-01-2015 at 05:07 PM.

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    trdtoy's Avatar
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    I can not wait to have the intake I have in mind on my car to show everyone along with test data.
    Peeps will be trying to find drool emoticons to post.....
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    sounds cool,..your choice of the cowling will be the make or break.

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    Large diameter with mandrel bends.....
    More flow coming in at road speed than any turbo you could fit between the engine and the firewall.....
    Very little restriction in a Dyno situation, but that section could be removed so.....

  7. #16
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    Sent you a PM whiteboy. Thanks
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    Quote Originally Posted by Gaijiin View Post
    With the installation of my new SS turbo comes new and unknown territory as to its capacity to draw in and conversely evacuate its exhaust. The efficiency of this device far exceeds the stock Borg Warner.

    In preparation for this installation, the wisdom of a full 3 inch exhaust, and a completely open CF hood will enhance these properties.
    In both the ability to draw cool fresh air unrestricted, and conversley dump exhaust gases more efficiently.

    Regardless of intake (air) or exhaust, the desired principles of Laminar flow are to be applied.
    Much reading on the topics thus far has yielded thew following general concepts in terms of accentuating positive laminar flow:

    1. Distance traveled whether intake or exhaust. (As short as possible)
    2. Diameter of conduit. Larger is always better.
    3. Cross--section (lateral)of conduit relative to concentric rings of travel and their speed.
    4. Avoiding bends if possible, reduce the degree as much as possible. i.e. 45 degrees is much more desirable than a 90 degree
    5. Never forcing a combination of a bend as well as a diameter reduction in the same location. ex. One should never have a reduction in the middle of a bend.
    6. Reductions in diameter if done in slight increments, in succession can result in increased pressure and speed (of central concentric rings).
    Ok, I'm going to try discuss some of the things you mentioned as best as I can, because the way you have described them is confusing me a little bit.
    I am going to keep my post in reference to the intake side of the discussion. This is because the conversation thus far is talking about the intake system. I can make a separate post on post-intercooler conditions as well as exhaust later. Although the optimum exhaust is pretty straight-forward and pretty understood by all.

    The ultimate goal is to keep the turbo in it's peak efficiency through all operating conditions. We must base efficiency off the turbo's Compressor Map. Does the Super Stock turbo have an established Compressor Map?
    I have found the stock turbo's map for reference.



    The Y-axis is the one we deal with when talking about the intake system (from air filter to turbo).
    I think we should only discuss operation at WOT for the following discussion to keep things constant, and that is what were are ultimately concerned with anyway

    The is the formula for Pressure Ratio below:
    (source for the following info - https://turbobygarrett.com/turbobyga...pressure_ratio)

    P2c / P1c

    P2c = Compressor Discharge Pressure
    P1c = Compressor Inlet Pressure

    - P2c - Compressor Discharge pressure is your boost pressure you are running, measuring in psia (absolute psi measured). I would guess you will be doing north of 20 psig (gauge psi measured) which is approx 34.7 psia (20+14.7).
    - P1c - Compressor Inlet pressure is just that, psia at the inlet of the turbo. Without using gauges to measure actual psia at the inlet, it's hard to tell what value to use here. This value is obviously based on the characteristics of the intake system. We all know the more restrictions you have, the more you have pressure drop, and that can affect the pressure ratio you are operating at. No intake is the best intake for turbo. This way we know what inlet pressure is for the most part, it's normal atmospheric pressure at your altitude.

    So this leads me to your first statement.

    Regardless of intake (air) or exhaust, the desired principles of Laminar flow are to be applied.
    I'd like to know how you came to this conclusion. Please cite links or quotes.

    Are you saying that laminar air flow is the basis for making more power vs turbulent flow? Because I think that statement is a little too general and not quite the basis for making power, or what you ultimately want and that is the turbo being its most efficient.

    I'm going to lay out how what you are saying is may be true, but this characteristic of laminar flow shouldn't be what you are chasing.

    Much reading on the topics thus far has yielded thew following general concepts in terms of accentuating positive laminar flow:
    what do you mean by positive? a direction?

    Laminar flow is a characteristic determined by a DIMENSIONLESS number called the Reynold's number. This number is calculated from the following equation:
    (source: Reynolds Number)

    Re = (p times u times L) / v

    where:

    p = fluid density (in our case, air)
    u = velocity based on pipe cross-sectional area
    L = length of pipe
    v = kinematic viscosity of the fluid (in our case, air)

    Reynolds number has a range that determines Laminar flow, transient flow, or turbulent flow

    Laminar - when Re < 2300
    Transient - when 2300 < Re < 4000
    Turbulent - when Re > 4000

    If we want to control turbulence, we only have a couple options.

    - The fluid density of air (p) is we can attempt to control with Cold Air intakes, or heat wrap insulation. Or we just accept it as it is if we are running the turbo with no intake lol
    - We can control velocity (u) by adjusting pipe size
    - We can control the length (L) obviously
    - We can't control viscosity - that is pretty much a constant

    Looking at the equation we can see what causes the Re to go turbulent that we are in direct control of:

    - If we increase length L, Re goes up
    - If we increase velocity u, Re goes up

    We all know the rule of thumb don't make the intake system too long or have too much pipe. However we might sacrifice here for temperature decreases from a Cold Air intake.
    A balance between temperature achieved by the cold air intake and pressure drop from the piping used must be achieved. Or, we have a really good intercooler to decrease temps and the intake side we don't care about :P

    My argument here is we are optimizing pressure drop, but I'll get there in a minute

    What about velocity u? Well, velocity is derived by:

    Velocity = air flow / area (cross-sectional area of pipe)

    So, that means if we hold flow constant, velocity and area have an inverse relationship. Area gets smaller, velocity gets faster and vice-versa.
    If we increase the pipe diameter, velocity goes down, hence Re goes down with it.

    Well, what does all of this have to do with Pressure Ratio like you said in the beginning?

    Well that brings us to the Darcy–Weisbach equation. This is the basis for head loss (or pressure loss) in pipes.

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    deltaP = pressure drop
    lambda - friction factor (we all use nice smooth pipes, we can treat this as a constant) (This is also why the stock intake tube is so bad, it has all those ribs!!!)
    L = Length of Pipe
    D = Diameter of pipe
    p = density (we will treat this as constant)
    w = velocity

    Analyzing the equation, we can confirm that:

    - if we increase L, pressure loss also increases all other things constant.
    - if we increase pipe diameter D, pressure loss decreases. If we apply the principles of a limit to D, as D approaches infinity > L/D = 0. By infinite D, I am saying a pipe of infinite diameter, or no pipe at all
    - If L/D = 0, then deltaP = 0 and there is no pressure drop because there is no intake pipe.

    Which brings me back to the beginning of my post.

    Since we have 14.7 psia in the world around us and that is the pressure as it hits the air filter, then we'd like the pressure at the turbo to be as close to that as we can.

    I don't have the time right now, but look at a couple different small turbo's compressor maps (that would be suitable for our engine) and:

    - calculate the pressure ratio using our stock boost level at WOT at peak torque - which I can estimate is about 14-15 psig (or 28-29 psia)
    - visualize a line across the map at that pressure ratio, I'm willing to bet that line is on the highest efficiency "islands" of the map for most of the graph

    Disclaimer

    Fluids is not my strongest suit, I did alright on it in school and I haven't been using it so much in my professional career as to say I'm a seasoned expert so anyone who is more versed in the subject please correct me if I am wrong on what I've posted.

    I feel I've only really regurgitated the basics here and a lot of our conjecture would be backed up with solid testing proof anyways!

    I know anyone who has a good background or professional career in HVAC would be able to shine even more light here.

  9. #18
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    Need ice. Head hurts.
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    Laminar flow working group

    Quote Originally Posted by 6thelementengineering View Post
    big block of text
    awesome
    Last edited by swordfish; 11-02-2015 at 11:22 AM.

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    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!!!
    Last edited by Gaijiin; 11-02-2015 at 11:43 AM.

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