html5-img
1 / 15

Fluids

Fluids. Fluids. Flow Take shape of container Liquids or gases Exert pressure Pressure = force / area. http://i.ehow.com/images/GlobalPhoto/Articles/5122397/246186-main_Full.jpg. Fluids. Move from high pressure  low pressure If no pressure difference, no motion (equilibrium).

sailor
Télécharger la présentation

Fluids

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. Fluids

  2. Fluids • Flow • Take shape of container • Liquids or gases • Exert pressure • Pressure = force / area http://i.ehow.com/images/GlobalPhoto/Articles/5122397/246186-main_Full.jpg

  3. Fluids • Move from high pressure  low pressure • If no pressure difference, no motion (equilibrium) http://rt492.org/dl/img/jetcar.gif http://images.google.com/imgres?imgurl=http://hyperphysics.phy-astr.gsu.edu/Hbase/fluids/flupic/bernlev.jpg&imgrefurl=http://hyperphysics.phy-astr.gsu.edu/Hbase/pman.html&usg=__zR0eA8X2YfzjNx1oK3YEqTgA9fg=&h=411&w=359&sz=33&hl=en&start=65&um=1&itbs=1&tbnid=ZKd7dOr6DEn4YM:&tbnh=125&tbnw=109&prev=/images%3Fq%3Dfluid%2Bpressure%2Bdifference%26ndsp%3D21%26hl%3Den%26safe%3Dactive%26rlz%3D1T4GGIH_enUS266US269%26sa%3DN%26start%3D63%26um%3D1 http://i.telegraph.co.uk/telegraph/multimedia/archive/01485/eyedrops_1485563c.jpg

  4. Calculating fluid pressure • Pressure = force / area • Force measured in lbs or N • Area measured in cm2 or inch2. • Area = Pr2or length * width • Radius =1/2 diameter http://www.sweethaven02.com/Aviation/AvEngines01/fig0101.gif

  5. Liquids • Not compressible; pressure difference supplied by pump • Basis for hydraulic systems (usually water or oil) • More dense than gases; molecules close together http://www.chemprofessor.com/liquids_files/image005.jpg

  6. Gases • Compressible; pressure difference supplied by compressor • Basis for pneumatic systems (usually utilize compressed air) • Less dense and therefore more buoyant http://www.grc.nasa.gov/WWW/K-12/airplane/Images/state.gif

  7. Basic components of fluid system • Tank, reservoir or accumulator – holds fluid • Pump (liquid) or compressor (gas) – creates pressure difference • Valve or regulator – control flow • Actuator – device that changes fluid pressure to linear or rotational mechanical movement. Often an arm, piston, etc. • Conductor – pipe, tubing, hose

  8. Pascal’s Principle • Pressure exerted on confined fluid is transmitted equally to all parts of the fluid within the closed container • P = F1 / A1 = F2 / A2 • Results: • Pressurized gas, when released, allows for propulsion (rockets, balloons) • Pressure in hydraulic systems allows movement of very heavy loads (hydraulic lift)

  9. Boyle’s Law • Volume increases when pressure decreases (temp stays constant) P1V1 = P2V2 • When P goes up, V goes down (inverse relationship) • Applies to astronauts walking in space, and to scuba divers

  10. Charles’ and Gay-Lussac’s Law • Volume increases when temp increases (pressure stays constant). V1 / T1 = V2 / T2 • Hot air balloons use this concept http://www.google.com/search?hl=en&safe=active&rlz=1T4GGIH_enUS266US269&q=Charles%27++law&start=10&sa=N

  11. Bernoulli’s Principle • Pressure of a moving fluid decreases as velocity increases • Basis for airplane wing design http://www.sweethaven02.com/Aviation/AvEngines01/fig0101.gif

  12. Fluid Power Physics Work Force multiplied by distance Measured in foot-pounds or Newton-meters Example: How much work is completed by moving a 1000 lb force 2 ft? 2000 foot-pounds of work

  13. Fluid Power Physics Power The rate of doing work Work over time in seconds Example: How many units of power are needed to lift a 1000 pound force 2 feet in 2 seconds? 1000 units of power (1000lb x 2ft) / 2 s

  14. Fluid Power Principles -- Units Watt – measure of power in SI system Pressure x volume flow rate Horsepower –measure of power in English system Hydraulic horsepower is expressed as:

  15. Fluid Power Principles Calculate the horsepower needed in the system below to lift a 10,000 lb force in 2 s.

More Related