External Flow: Convection heat transfer & Thermal boundary layer Flashcards
what is the general heat transfer equation for convection?
Nu =C Re^.5 Pr^(1/8) = hl/k
what is the Nusselt Number for laminar flow
Nu = 0.664Re^.5Pr^(1/8)
What is the Nusselt number for turbulent flow
Nu = 0.037Re^0.8Pr(1/8)
what letter denotes heat transfer coefficient
h
what letter denotes fluid thermal capacity
k
what letter denotes specific heat capacity
Cd
what is the equation for heat transfer per unit length
Qdot = h*As(Tinf. - T)
what is a thermal boundary layer and how is it formed
formed when there is a difference in temp between a plate and the fluid
fluid particles at the wall are heated to the same temp
adjacent layers are heated, forming a temperature profile
how is the thickness of the boundary layer determined (hint: displacement thickness)
delta(t) = delta/(Pr^(1/3) = 5x/(pr^(1/3) * Re ^.5)
how else is thermal boundary layer found (hint: 0.99)
when difference in temp = 0.99 (Tinf. - Ts)
How is the Nusselt number calculated
Nu= hL/k
how is the prandtl number caluclated
Pr = M*Cp/k
