This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Lecture F12 Mud: Energy Conservation ˙ E 1. What’s the difference between dE/dt and E ˙ ﬂow ? (1 student) dE/dt is the rate of change of energy contained by the mass already in the volume. ﬂow is haw fast energy is being brought into or out of the volume by inﬂowing and outﬂowing mass. ˙ 2. What’s the difference between Q ˙ viscous and W viscous ? (1 student) Imagine a viscous friction force F f rubbing on the surface of the CV, much like a boundary layer “rubs” on the surface of an airfoil. This force does work if there is ˙ ﬂuid velocity at the point of application, W viscous = F f · V . But if there’s a friction force, there must also be frictional heating present (a boundary layer is always slightly warmer than the effectively-inviscid ﬂuid next to it). This excess heat will ﬂow into the CV, and constitute Q ˙ viscous . 3. How do the physical definitions of h and h o and h o differ? (1 student) The static enthalpy h measures only the energy of the molecules...
View Full Document
This note was uploaded on 01/28/2012 for the course AERO 16.01 taught by Professor Markdrela during the Fall '05 term at MIT.
- Fall '05