1 / 38

ÓBUDA UNIVERSITY

ÓBUDA UNIVERSITY. FLUID MECHANICS LECTURE. Only using inside. Dr. Ferenc Szlivka professor. Friction flow in tube Chapter 9. Laminar and turbulent flow. Laminar flow. Turbulent flow. Laminar and turbulent flow. Laminar and turbulent flow. a./ Laminar flow. b./ Turbulent flow.

jasonbeverly
Download Presentation

ÓBUDA UNIVERSITY

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. ÓBUDA UNIVERSITY FLUID MECHANICS LECTURE Only using inside Dr. Ferenc Szlivka professor Dr. Szlivka: Fluid Mechanics 9.

  2. Friction flow in tubeChapter 9. Dr. Szlivka: Fluid Mechanics 9.

  3. Laminar and turbulent flow Laminar flow Turbulent flow Dr. Szlivka: Fluid Mechanics 9.

  4. Laminar and turbulent flow Dr. Szlivka: Fluid Mechanics 9.

  5. Laminar and turbulent flow a./ Laminar flow b./ Turbulent flow Dr. Szlivka: Fluid Mechanics 9.

  6. Turbulent flow Smog flow Flow around a cylinder (Kármán vortex street) Dr. Szlivka: Fluid Mechanics 9.

  7. Pressure loss in a straight pipe There is a friction loss Darcy-formula Dr. Szlivka: Fluid Mechanics 9.

  8. Solution of Navier-Stokes equation in tube „l" is the length , with Dp’the pressure loss Dr. Szlivka: Fluid Mechanics 9.

  9. Solution of Navier-Stokes equation in tube for laminar flow Darcy-formula where Re is the Reynolds’ number Dr. Szlivka: Fluid Mechanics 9.

  10. Straight pipe pressure loss in turbulent flow Reynolds’ number "v" is the average velocity, "d" is the pipe diameter "r" density of fluid "m" dynamic viscosity. The pipe wall is not smooth because of the producing process or the corrosion. The average roughness is k and the relative roughness k/d, or the reciprocal of it is d/k. Dr. Szlivka: Fluid Mechanics 9.

  11. Nikuradse-diagram Dr. Szlivka: Fluid Mechanics 9.

  12. Moody-diagram Dr. Szlivka: Fluid Mechanics 9.

  13. Roughness of different materials Dr. Szlivka: Fluid Mechanics 9.

  14. Moody-diagram Haaland-formula Dr. Szlivka: Fluid Mechanics 9.

  15. Three different pipe problems • Given the diameter of the pipe "d", the length of pipe „l", the average diameter "v" , or the volume flow rate „ qv ", and the data of fluid: density "r" and viscosity "m", The question is the pressure loss "Dp". • II. Given the diameter of the pipe "d", the length of pipe „ l ", and the pressure loss Dp', and the data of fluid: density "r" and viscosity "m", • The question is the volume flow rate " qv ". • III. Given the length of pipe „ l ", the pressure loss Dp', the volume flow rate „qv", and the data of fluid: density "r" and viscosity "m„. • The question is the diameter of the pipe "d". Dr. Szlivka: Fluid Mechanics 9.

  16. I. pipe problem Calculate the pressure loss in an asphalted cast-iron pipe. Water is flowing in it data: Solution: From the 8.1 table look out the dynamic viscosity. Dr. Szlivka: Fluid Mechanics 9.

  17. 10 1 10-1 10-2 1,3*10-3 10-3 10-4 10-5 Dr. Szlivka: Fluid Mechanics 9.

  18. Dr. Szlivka: Fluid Mechanics 9.

  19. 0,028 1250 Dr. Szlivka: Fluid Mechanics 9.

  20. II. pipe problem Calculate the average velocity in an asphalted cast-iron pipe! data: Solution: We don’t know the average velocity (or the volume flow rate) so we can’t calculate the "l"-and the Re number. So we should make an iteration process. Fortunately the process is fast. Look out the roughness and the. Dr. Szlivka: Fluid Mechanics 9.

  21. We don’t know the Re number, the velocity is unknown. So we assume beginning l0=0,02 - 0.03. In this case l0=0,02. 1250 Dr. Szlivka: Fluid Mechanics 9.

  22. Make a formula from Darcy’s formula. Dr. Szlivka: Fluid Mechanics 9.

  23. 0,026 4,073*104 Dr. Szlivka: Fluid Mechanics 9.

  24. Check the relative error between two steps If the difference is biger than 10% , we calculate once more! Dr. Szlivka: Fluid Mechanics 9.

  25. A new l from the Moody diagram. Check the relative error. The difference is smaller than 10%, so it is the final result. The average velocity is: Dr. Szlivka: Fluid Mechanics 9.

  26. III. pipe problem (design problem) data: Solution: The question is the diameter „d”. "l", and the Re-number, are depending on the velocity (which is unknown) we should make an iteration process. To solve the problem we choose a standard pipe diameter, which can be bought. The usual average velocity is 1-2 m/s . Dr. Szlivka: Fluid Mechanics 9.

  27. The diameter was choosen 5 in d=128,2 mm. The solution after is the I. problem. In these case: Dr. Szlivka: Fluid Mechanics 9.

  28. 0,026 1068 Dr. Szlivka: Fluid Mechanics 9.

  29. The calculated pressure loss is bigger than the given pressure loss. So we should choose a bigger diameter but only with one step bigger diameter ! (Unless the pipe is to expensive.) The calculated pressure loss is smaller than the given one. With a trothling we it can be made the difference. Comment: Put the volume flow rate into the Darcy’s formula: Dr. Szlivka: Fluid Mechanics 9.

  30. Comment: Puting the volume flow rate into the Darcy’s formula: The formula shows: If the diameter is 10% smaller the pressure loss rises approximately 50%! Dr. Szlivka: Fluid Mechanics 9.

  31. Noncircular pipes where “K" is called the wetted perimeter (may also be a flow where the fluid does not fill completely the cross-section, eg. an open channel)"A" is filled with the liquid cross-section. Dr. Szlivka: Fluid Mechanics 9.

  32. Noncircular pipes pressure loss Take the idea of a circular cross-section pipe, in which an equal pressure drop is created in case the same length and the same shear wall. Find thisdiameter of the circle, which is called as equivalent diameter. Dr. Szlivka: Fluid Mechanics 9.

  33. Fitting pressure losses Dr. Szlivka: Fluid Mechanics 9.

  34. Valves Dr. Szlivka: Fluid Mechanics 9.

  35. Valves, taps, loss coefficience, equivalent pipe length Dr. Szlivka: Fluid Mechanics 9.

  36. Csőkönyökök Bends, elbows loss factor, the equivalent pipe length Dr. Szlivka: Fluid Mechanics 9.

  37. Dr. Szlivka: Fluid Mechanics 9.

  38. Dr. Szlivka: Fluid Mechanics 9.

More Related