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61 Cards in this Set
- Front
- Back
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Who will pass the PE
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Me!
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What is the best Engineering forum on the planet
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Engineerboards.com
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Energy of a mass
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the capacity of a mass to do work
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Joule's Constant
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778 ft-lbf/Btu
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work (def)
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the act of changing the energy of a particle, body, system
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potential energy (def and eq)
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a form of mechanical energy possessed by a body due to it's position in a gravitational field
E=m*g*h/gc E is per unit mass in the fluids chapters and not in the thermo chapters |
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kinetic energy (def and eq)
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a form of mechanical energy associated with a moving or rotating body
E=m*v^2/(2*gc) E is per unit mass in the fluids chapters and not in the Thermo chapters |
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Convert from rpm to rad/sec (eq)
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rpm*2*pi/60
or rpm *0.1047 |
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Ideal fluids (def)
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has no viscosity, & is incompressible
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absolute pressure (def)
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measured with respect to a true 0 pressure reference
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gage pressure (def)
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measured with respect to atmospheric pressure
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Standard atmospheric pressure (numerical value)
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1 atm
14.7 psia |
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Density (def)
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a fluid's mass per unit volume
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Specific gravity (def)
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a dimensionless ratio of a fluid's density to some standard reference density
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Specific wieght (def)
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the weight of a fluid per unit volume
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absolute viscosity (def)
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μ
a measure of that fluid's resistance to flow when acted upon by an external source |
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kinematic viscosity (def)
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∨
the ratio of absolute viscosity to mass density |
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hydrostatic pressure (def)
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pressure a fluid excerts on an immersed object or container walls
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The relationship between pressure and depth (eq)
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p=ρ*g*h/gc
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gravitational constant (numerical value)
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32.2 lbm-ft/(lbf-sec^2)
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laminar flow (numerical value)
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re below 2100
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Reynolds number (eq)
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Re=D*V*ρ/(gc*μ)
Re=D*v/∨ Re=D*G/gc*μ G=mass flow rate per unit area |
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Turbulent flow (numerical value)
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re greater than 4000
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mass flow rate (eq)
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ρ*A*v
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laminar flow eq for friction factor (eq)
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f=64/Re
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darcy equation (eq)
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hf=(f*L*v^2)/(2*D*g)
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Specific energy (def and units)
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energy per unit mass ft-lbf/lbm
E is per unit mass in the fluids chapters and not in the thermo chapters |
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Ef (specific frictional energy) (eq)
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Ef=(f*L*v^2)/(2*D*gc)
E is per unit mass in fluids chapters and not in the thermo chapters |
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head loss due to pressure drop (eq)
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deltap=hf*ρ*(g/gc)
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Fluid velocity in terms of mass flow rate, density, and area (eq)
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v=mdot/(ρ*A)
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terminal velocity (def)
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the velocity of an object falling through a fluid will continue to increase untill the drag force equals the net downward force
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frictional head (eq)
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hf=(f*L*v^2)/(2*D*g)
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velocity head (eq)
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hv=(v^2/2*g)
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static suction head hz(s) (def)
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the vertical distance above the centerline of the pump inlet to the free level of the fluid surface. If the free level of the fluid is below the pump inlet, hz, will be negative and is known as static suction lift
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static discharge head hz(d) (def)
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The vertical distance above the centerline of the pump inlet to the point of free discharge or surface level
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weight (eq)
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W=m*g/gc
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acceleration of gravity (numerical value)
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32.0 ft/sec^2
9.8 meter/sec^2 |
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Area and circumference of a circle (eq)
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A=π* r^2
C=2*π*r |
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volume and surface area of a shere (eq)
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V=4*π*r^3/3
A=4*π*r^2 |
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Right triangle equations (eq)
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Some Old Hags Can't Hide There Old Age
sin= opposite side/ hyp cos= adj side/ hyp tan= opposite side/ adj side a^2 + b^2 = c^2 |
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Power (eq and def)
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is the amount of work per unit time
P=W/Δt P=F*v (linear systems) P=T*ω (rotational systems) |
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what the eq that relates lbm to slugs (eq)
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Lbm=slugs*g (g in ft per sec2)
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density of water at STD (numerical value)
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62.4 lbm/ft^3
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1 HP equals? (eq to change units)
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hp=550 ft-lbf/s
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How are mass and volume related (eq)
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m=ρ*V
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What is a subcooled liquid (def)
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If a liquid is not saturated (not at it's boiling point) it is said to be subcooled. Water at room temp is subcooled since adding a small amount of heat will not cause vaporization
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what is a saturated liquid (def)
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a liquid that has absorbed as much heat energy as it can without vaporizing. Liquid water at 212F is an example
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liquid vapor mixture (def)
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a liquid and vapor can coexist at the same temp and pressure.
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saturated vapor (def)
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a vapor on the verge of condensing. steam at 212F and STD pressure
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superheated vapor (def)
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is a vapor that has absorbed more heat than is needed merely to vaporize it. A superheated vapor will not condense when a small amount of heat is removed
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ideal gas (4 eq)
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p*V=Rstar*T
p*V=n*R*T ρ=p/(R*T) mdot=p*Vdot/(R*T) note R is gas specific and Rstar is not. |
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What is a gas (def)
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a highly superheated vapor
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specific volume in terms of density, and what are the units for specific volume (eq)
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ν=1/ρ
ft3/lbm |
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enthalpy (def)
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is the total useful energy of a substance (internal energy, u, and flow energy, p*V. Define as useful energy because all of it can be used to preform useful tasks.
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entropy (def)
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a measure of the energy that is no longer available to proform useful work within the current environment
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The specific gas constant, R, for air is
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53.35 ft-lbf/(lbm-degreeR)
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Eq for Mass flow rate
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mdot=ρ*v*A
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What is the Energy Efficiency Ratio? (eq)
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EER=3.41*COP
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What is the Sefan Boltzman Constant (numerical value)
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5.67*10^(-8) Btu/hr*ft^2-R^4
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Sensible Heat (def)
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pure thermal energy that increases the air's dry bulb temp
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Latent heat (def)
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moisture that increases the air's humidity ratio
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