ADVANCED THERMAL ENGINEERING
INTRODUCTION
Heat transfer describes the exchange of thermal energy, between physical systems depending
on the temperature and pressure, by dissipating heat. The fundamental modes of heat transfer
are conduction or diffusion,
FLOW OVER FLAT PLATES
Flows over objects are categorized as external flows. E.g. flow over a flat plat, flow over
a turbine blade, flow over a cylinder or sphere.
Numerous engineering applications such as those in:
Gas turbine blade cooling, shell and tub
Principles of convection
Similarities between transport of momentum and heat
The Cauchy momentum equation is a vector partial differential equation put forth
by Cauchy that describes the non-relativistic momentum transport in any continuum:[1]
where is th
PRINCIPLES OF CONVECTION: AN INTRODUCTION TO
HYDRODYNAMIC AND THERMAL BOUNDARY LAYERS
Convective heat transfer coefficient
The heat transfer coefficient or film coefficient, in thermodynamics and in mechanics is
the proportionality coefficient between the
Flows over cylinders and spheres
The characteristic length for a circular tube or sphere is the external diameter, D, and the Reynolds
number is defined:
=
The critical Re for the flow across spheres or tubes is 2x105 . The approaching fluid to the cyl
PRINCIPLES OF CONVECTION:
FUNDAMENTAL EQUATIONS OF CONVECTION TRANSFER IN
BOUNDARY LAYERS
Conservation of mass
1. In a steady flow, the net rate in which mass enters the control volume (inflow-outflow)
must equal zero.
2. Applying this to a differential