Recent content by kibestar

  1. K

    I Reversible compression of a gas - faulty reasoning?

    I believe it really comes to the non-zero temperature/pressure pair, as you pointed out. At first I had envisioned absolute zero temperature and pressure for this hypothetical process. However at that stage, the definition of entropy ceases to be mathematically sound. Lowering the temperature of...
  2. K

    I Reversible compression of a gas - faulty reasoning?

    Hello, I am trying to figure out where my reasoning falls apart in this thought experiment: To determine if a process "A" is reversible (or at the very least internally reversible), I try to picture a reversible process "B" that involves only heat transfer and links the same two endpoints that...
  3. K

    Can't understand how flow work is possible in a control volume

    Now this is uncanny; I just thought about exactly that! Both situations are really analogous. I think my discomfort with this boils down to time being continuous, which, for velocity, never presented any issue for me; I suspect it's simply because we are just so used to thinking of velocities in...
  4. K

    Can't understand how flow work is possible in a control volume

    The thing is, to me, when the interval becomes vanishingly small, the situation stops making sense physically. Following that train of thought, I can only see it as being logically consistent if time evolved in discrete steps. This is how my mind reads this: The only moment at which fluid out...
  5. K

    Can't understand how flow work is possible in a control volume

    I can definitely understand it mathematically, but physically it just seems like some "trick". As soon as those delta's are made to approach zero I just can't spiral out of "if it is supposed to be a form of boundary work, how does a non-moving boundary provide it??". At the same time, I realize...
  6. K

    Can't understand how flow work is possible in a control volume

    I am struggling to fully grasp the concept of flow work for a non-deformabable control volume. Nearly every source puts it in this way: flow work is the work required to push fluid into and out of the control volume and as such is defined as Pv on a unit mass basis. But how can this work be...
  7. K

    Pressure differential and air flow

    But why isn't the system of equations enough to find air flow? Two equations with two variables... What am I missing?
  8. K

    Pressure differential and air flow

    Is your "no" directed towards which statement? Use of compressible flow equation, non-need of taking into consideration the pump specifications, system of equations or everything?
  9. K

    Pressure differential and air flow

    Chet, I looked up Bernoulli's equation, and now I have some new questions! So I'd have to use the compressible flow equation for this situation? And, knowing the pressure in the bulk region, I wouldn't actually need to take into account the characteristics of the air pump in use, since I'd...
  10. K

    Pressure differential and air flow

    I'm sorry, I don't have knowledge of Bernoulli's equation (just graduated high school). Will look it up. With respect to the pressure drop/increase, I'm referring to the ones caused by the air pump in each plenum. Thanks, once more.
  11. K

    Pressure differential and air flow

    That was a very informative answer, thank you. What is a good approximation to consider the "bulk" of each chamber? And with regard to the exit holes, a modification on their area would produce what change in air flow (I'm assuming the pressure drop/increase would remain the same, since the...
  12. K

    Pressure differential and air flow

    OK, thank you, but what about all of my other questions?
  13. K

    Pressure differential and air flow

    I'm having a hard time understanding air flow caused by pressure differentials. Given the following contextual image, crafted by myself: Bare with me here, these are two interconnected boxes open to the Earth's atmosphere. The orange arrow represents an air pump, such as a vacuum...
  14. K

    How does an air flow bench work

    Thank you for your answer. But what if the flow bench is home made and the calculations are to be done manually? Suppose you turn the device on, disregard temperature differences between the plenums and read 'x' for the test manometer and 'y' for the metering manometer, what is to be made of...
  15. K

    How does an air flow bench work

    Hello, I'm new to these forums and they seemed like an excellent way to have my questions answered. I'll start by saying that I've never had any course that dealt with fluid mechanics (mechanical engineering freshman), so I'm having quite some trouble grasping how readings on an air flow...
Back
Top