ME200 01-02

What about an aircraft engine 22 properties property

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Unformatted text preview: trol volume) 21 Example 1-1 – Is this classroom an open or closed system? – What about an aircraft engine? 22 Properties – Property: – Independent properties: A 1 m3 container is fully filled with water. Since the water density is 1000 kg/m3, the total mass of the water is 1000 kg. Among the volume, density, and mass, how many of them are independent properties? 23 Properties – Extensive properties: – Intensive properties: m V T p ρ m 1/2 m 1/2 V 1/2 V T T p p ρ ρ 1/2 24 State and Equilibrium – State: The “conditions” of system as described by its properties For example, in this classroom, air temperature T, air density ρ, and relative humidity φ characterize the state. 25 State and Equilibrium Equilibrium: A state of balance with no unbalanced forces in the system. (Uniform p, T, C, etc.) – e.g. mechanical: forces (pressure) thermal: temperature phase: vapor-liquid chemical: combustion 26 Units – Basic quantities Physical quantity SI English mass kg lbm length m ft time s s temperature K R amount of matter mol lbmol electric current A A amount of light cd candles 27 Units – Derived quantities Force (Newton’s law of motion) SI force unit English force unit 28 Unit Conversion (See Equation Sheet) 29 2. Specific Volume, Pressure, Temperature, Engineering Design and Analysis, and Methodology - Specific Volume 30 Pressure – Pressure: p = normal force / area 31 Pressure For a column of fluid Free-body diagram p1A p1 ∆z ∆z mg p2 p2 A 32 Pressure – Atmospheric pressure vacuum patm fluid ∆z 33 Pressure – System pressure patm fluid ∆z gas psys psys 34 Pressure Example 2-1 Given: patm = 14.7 psia, g = 32.2 ft/s2, h = 100 ft, ρ = 62.4 lbm/ft3 – – – – Find: ppump Assumptions: Basic equations: vacuum 100 ft 35 Pressure Absolute, gage and vacuum pressure pabs pgage Atmospheric pressure – patm pvac Zero pressure 36 Pressur...
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