Important Definitions Flashcards
(10 cards)
Meridional velocity
Meridional velocity is the vector addition of the axial and radial velocity; it is distinct from the tangential velocity, in that it represents volume flow rather than power imparted to fluid.
Isentropic
A process that is adiabatic and reversible. This means that there is no change in entropy
Adiabatic
When no heat is transferred into or out from a system
Swirl Angle
Swirl angle is the angle between absolute velocity resultant, c, and the meridional velocity of the fluid, cm. Swirl relates the power given to the fluid to the flow rate through the machine.
Tangential velocity and work on a shaft in turbomachinery
Work at the shaft can only be from torque about the axis. Axial and radial velocity changes of the fluid do not affect the forces related to the torque about the axis. Therefore the work at the shaft is only related to tangential velocity change
Rothalpy
rotational enthalpy
Compressibility and interactions with shocks
For weakly compressible flows, up to Mach 1, prior to a strong shock wave, the flow is isentropic because there is no heat transfer in the flow and there are no strong irreversible effects due to viscosity. Where there is a shock, the friction effects caused across the shock, which lead to a rise in static pressure, are due to friction, so although adiabatic, they are not reversible due to friction.
Moderation in Nuclear reactors
Moderation implies the slowing down of neutrons from nuclear reactions to thermal speeds to enable the next fission reactions to occur.
Fin Effectiveness
The fin effectiveness is given by the ratio of the actual heat loss through thefin/the heat loss without the fin. It can have values from 0 to infinity.
Ideal Fin
An ideal fin is one where the surface temperature of the extruded surface is the same as the base of the fin.
