Notes_13_Control_Volume_Conservation_of_Energy

# Notes_13_Control_Volume_Conservation_of_Energy - Meeting...

This preview shows pages 1–10. Sign up to view the full content.

1 Meeting 12--Sections 5-2—5-3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
What we covered last week Conservation of mass for a control volume 2
Topics for Today Flow energy Energy carried into a control volume by mass The First Law for a control volume 3

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Example A 4-ft high, 3-ft diameter cylindrical water tank whose top is open to the atmosphere is initially filled with water. The discharge plug near the bottom of the tank is pulled out, and a water jet whose diameter is 0.75 in streams out. The average velocity of the jet is approximated as V=(2*g*h)^0.5, where h is the height of the water in the tank measured from the center of the hole and g is the gravitational acceleration. Determine how long it takes for the water level in the tank to drop 3 ft from the bottom. 4
Teamplay A 100,000 gallon pool is being filled by a fire hose with a flow rate of 100 gal/hr. Beginning from the conservation of mass equation, applying assumptions, and solving the ODE, determine how long (in hours) it will take to fill the pool? 5

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Remember the difference between closed and open systems
7 Flow work For open systems, obviously work must be done to move the fluid into and out of the control volume. It is a form of boundary work. “piston” of fluid having m, P, V. A is crossectional area of pipe. L Flow

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
8 Flow work The force on the fluid element F=PA But AL is V, so W=PV or F and P have been assumed uniform over the surface A. = = = = PAL FL ds F Fds W Pv m V P w m W = = =
Energy of fluid in closed system Remember from Chapter 2. Energy of a simple, compressible system is

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 10/04/2011 for the course MEEN 315 taught by Professor Ramussen during the Summer '07 term at Texas A&M.

### Page1 / 30

Notes_13_Control_Volume_Conservation_of_Energy - Meeting...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online