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ENTC 303 Announcements

ENTC 303 Announcements. A lab manual is available for this course PDF version is available on line through eCampus We will have labs starting next week: 8-12 September We will meet at Thompson 008 (DXP Pump Lab). Key Concepts/Properties. Pressure :

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ENTC 303 Announcements

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  1. ENTC 303 Announcements • A lab manual is available for this course • PDF version is available on line through eCampus • We will have labs starting next week: 8-12 September • We will meet at Thompson 008 (DXP Pump Lab)

  2. Key Concepts/Properties • Pressure: • Amount of Force exerted on a unit area • P = Force/Area • Pressure acts uniformly in all directions and perpendicular to the boundaries in the container • Example: Piston Force Area= p/4*D2 P Pressure=Force/Area Unit: Psi or Pa (SI)

  3. Example • A container holding a liquid supports a loaded movable piston. Determine the magnitude of the pressure in the liquid under the piston if the total weight of the piston and load is 500 N, and the area of the piston is 2500 mm2.

  4. Key Concepts • Density, r: • Amount of mass per unit volume • r = mass/volume • Density is a fluid property and slightly dependent on temperature • Units: kg/m3, g/cm3, lb/ft3 • Specific Volume, n: • Inverse of density • n = 1/r, m3/kg

  5. Key Concepts • Specific Gravity, SG: • Is the ratio of density of fluid to the density of reference fluid (usually water) at the same temperature • SG=r/rwater • SG of seawater in the death sea (SG = 1.24): • https://www.youtube.com/watch?v=aTcyACmiaho • SG of men: 0.96 • SG for women: 0.91 • http://jap.physiology.org/content/19/5/955

  6. Specific Weight • Specific Weight (g) = Weight/Volume g = w/V • Examples • Calculate the weight of a reservoir of oil if it has a mass of 825 kg • If the volume is 0.917 m3, compute density, specific weight, specific gravity

  7. Equations for Property Calculations • Circular Area: • Weight: w = m*g • Density: r = m/V • Specific Weight: g = w/V • Specific gravity: SG=r/rwater Area = p/4*D2

  8. Examples • Glycerine at 20° C has a specific gravity of 1.263. Compute its density and specific weight.

  9. Surface Tension • Property by which droplets of water (or water molecules) adhere to each other and other surfaces • When water molecules stick to each other: cohesion • When they stick to other substance: adhesion • Surface tension varies with temperature; decreases with increase in temperature.

  10. Examples of Surface Tension Surface tension helps the spider walk on water. The force of surface tension balances the spider’s weight, helping it to walk on water. Surface tension affects the top layer of water, causing it to behave like a stretched elastic sheet. http://udel.edu/~inamdar/EGTE215/Introduction.pdf

  11. Wetting glv Hydrophobic Hydrophillic gsl gsv Young equation (1805) qeq qeq = contact angle

  12. Viscosity • Dynamic Viscosity • = Shear Stress/Slope of velocity profile • = n v F Slope = v/y y Units: cP (centipoise), mPa-sec http://www.brookfieldengineering.com/education/learn-about-viscosity.asp

  13. Newtonian and Non-Newtonian Fluids • Rheology: Study of the deformation and flow characteristics of fluids • Two types of fluids: Newtonian and Non-Newtonian: Shear Rate or Velocity Gradient

  14. Viscosity • Kinematic Viscosity • Units: cS (centistokes) mm2/s • 0.10 mm2/s to 70,000 mm2/s

  15. Newtonian and Non-Newtonian Fluids Bingham Pseudoplastic Newtonian Shear Stress Dilatant Velocity Gradient

  16. Newtonian and Non-Newtonian Fluids

  17. Newtonian Fluids • Water • Oil • Gasoline • Alcohol • Kerosene • Benzene • Glycerine

  18. Newtonian Fluids

  19. Non-Newtonian

  20. Non-Newtonian Fluids • Time-independent Fluids • Pseudoplastic (Blood Plasma, syrups, inks) • Dilatant (Starch in water) • Bingham (catsup, mustard, toothpaste) • Carbon nanotube-based nanofluids • Time-dependent Fluids • Electrorheological (behavior changes due to electric field, particles are present) • Magnetorheological (iron powders in fluid) • http://en.wikipedia.org/wiki/Power-law_fluid • http://www.youtube.com/watch?v=f2XQ97XHjVw&feature=PlayList&p=E93EA958CFFF93FC&playnext=1&playnext_from=PL&index=6

  21. Carbon Nanotubes in PAO fluid

  22. CNT

  23. Viscosity MeasurementRotating Drum Viscometer

  24. Viscosity MeasurementRotating Drum Viscometer Drum --Velocity at cup wall is zero --Fluid near drum moves with velocity of drum --du/dy is known Cup dy

  25. Viscosity MeasurementCapillary Tube Viscometer • Capillary Tube • Makes use of pressure drop to determine viscosity Equation 2-5:

  26. Viscosity MeasurementCapillary Tube Viscometer Upper timing mark Filled with test fluid Suction draws fluid through bulb and above timing mark Suction removed and fluid flows by gravity Time is recorded between upper and lower marks Bulb Lower timing mark

  27. Viscosity MeasurementFalling Ball Viscometer • Viscosity is determined by noting the amount of time a ball takes to travel between two lines

  28. Viscosity MeasurementFalling Ball Viscometer W Fb Fd

  29. Viscosity MeasurementSaybolt Universal Viscometer • Ease of fluid flow through orifice is an indication of viscosity • Measurement is not based on definition of viscosity • Results are relative, so a standard sample is used for calibration • Fast and easy

  30. Saybolt Viscosity • Saybolt Equations: • (cS) = 0.226t - 195/t, t< 100 SUS • (cS) = 0.220t – 135/t, t> 100 SUS t, amount of time (seconds, SUS, Saybolt Universal Seconds) it takes for 60 cm3 to flow through orifice (Saybolt viscometer) • Example: • An oil has a viscosity of 230 SUS at 150° F. Compute the viscosity in cS and cP. Specific gravity is 0.9.

  31. http://en.wikipedia.org/wiki/SAE_viscosity_number#Grades http://www.liquidcontrol.com/etoolbox/viscosity.aspx

  32. Viscosity Chart m Force Temp. ° F  http://webbook.nist.gov/chemistry/fluid/ Temp. C http://www.klassenhydraulics.com/Reference/viscositychart.htm

  33. Hydraulics Fluids for Fluid Power Systems • Fluid Power • Pneumatics: air-type systems • Hydraulics: liquid-type systems • Hydraulic Fluids: • Petroleum oils • Water-glycol fluids • High water based fluids (HWBF) • Silicone fluids • Synthetic oils http://en.wikipedia.org/wiki/Hydraulic_fluid

  34. Characteristics of Hydraulic Fluids • Adequate viscosity • Lubricating capability • Cleanliness • Chemical stability • Non-corrosiveness • Ability to resist growth of bacteria • Ecologically acceptable • Low compressibility http://www.castrol.com/castrol/sectiongenericarticle.do?categoryId=9045295&contentId=7080615

  35. Hydraulic Fluids • HWBF • Fire resistant • ~40% oil in water • Water-glycol fluids • Fire resistant • 35 to 50% water https://engineering.purdue.edu/Maha/index.html

  36. Hydraulic Fluids • Petroleum Oils • SAE 10 W, SAE 20-20W (W means rated at maximum viscosity and cold temperatures) • Engine oils • Additives are required to avoid growth of bacteria • Silicone Fluids • For high temperature applications http://en.wikipedia.org/wiki/SAE_viscosity_number#Grades

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