FLUID FILM LUBRICATION
Reproduced mainly from
Introduction to Tribology by
Bharat Bhushan
and
Shigleys Mechanical Engineering Design
Introduction
The term "lubrication" is applied to two
different situations:
SOLID LUBRICATION [high loads and low speeds

Introduction
Blackbody radiation
Radiation laws:
The Planck Distribution
Wiens Displacement law
The Stefan-Boltzmann law
Band Emission
Emission from Real Surfaces
Emissivity (Spectral, directional, total, hemispherical)
Diffuse emitter concept
The
spectra

Introduction
Till now we considered the radiative processes for a single surface.
Now, radiative exchange between two or more surfaces will be considered.
This exchange depends strongly on the
Surface geometries
Orientations
Radiative properties
Temperatu

Introduction
Unsteady state heat conduction:
Some bodies are observed to behave like a lump, In heat transfer analysis,
whose interior temperature remains essentially uniform at all times during a
heat transfer process.
The temperature of such bodies can

Introduction
Fundamental laws
Subsidiary laws
The foundations of heat transfer rest on a number of
fundamental and subsidiary laws.
It is important to distinguish between the two types of laws.
Fundamental laws are the laws whose validity rests on the f

Introduction
Horizontal Plates:
Box or an ingot. The top surface is hot
Top surface of a cold circular can taken out of a refrigerator space
kept outside.
These are the situations where horizontal surface exchanges heat with the
surrounding fluid by natur

Introduction
Subsidiary laws:
These are empirical in nature.
We will use those laws which are of interest to us for a
particular situation.
The 3 subsidiary laws which will be of primary concern are:
Fouriers law of heat conduction
Newtons law of coolin

Introduction
Boiling is a liquid-to-vapor phase change process just like evaporation, but
there are significant differences between the two.
Evaporation occurs at the liquidvapor interface when the vapor pressure is
less than the saturation pressure of th

Introduction
1-D steady state problem with heat generation:
Infinite Slab:
Aim:
1) To find the temperature distribution in the infinite slab
2) To find the expression for maximum temperature (which will occur at the
centre, i.e., at x = 0)
x
x
-L
L
To
q
(

Introduction
Topics covered:
1) 1-D steady state
2) 1-D steady state
3) 1-D steady state
4) 1-D steady state
through
through
through
through
a
a
a
a
slab
cylinder
composite slab
composite cylinder
T = f(x)
If T varies in more than one direction and also v

Introduction
External Flow:
It is a flow around submerged bodies.
Consider a typical submerged body.
Airfoil is confronting a free stream.
One of the most important
concepts for such flows around
submerged body, is also known
as bluff bodies, is the bound

Introduction
In the lumped system analysis, we have neglected internal temperature
gradients.
So there is no variation of temperature in x, y and z directions in the body.
We just say temperature is a function of time, get a 1st order differential
equatio

INTRODUCTION TO
TRIBOLOGY
Harpreet Singh
School of Mechanical, Materials and
Energy Engineering
Tribology is the art of applying operational
analysis to problems of great economic
significance namely,
reliability,
maintenance, and
wear of technical eq

LUBRICANTS
Reproduced mainly from
The Tribology Handbook
By
M. J. NEALE
Mineral oils
CLASSIFICATION
Mineral oils are basically hydrocarbons
They are classified in various ways as follows.
Parafinic - Contains significant amounts of waxy
hydrocarbons an

EROSIVE WEAR
Reproduced mainly from
Engineering Tribology
by
GW Stachowiak and
AW Batchelor
Erosive wear
Erosive wear is caused on solid
bodies by the impacting action of
solids, liquids or gases or a combination
of these.
Tribosystems suffering erosive

ABRASIVE WEAR
Reproduced mainly from
Engineering Tribology by
GW Stachowiak and
AW Batchelor
Classification of wear processes
Burewell and Strang
abrasive wear, adhesive wear, corrosive wear, surface fatigue wear,
fretting, erosion and cavitation
Jahanmir

Surfaces
Properties different from that of the bulk
Have major impact on several areas including
semiconductors, metal corrosion, detergents, and
TRIBOLOGY
Specialised techniques required to study
topography and chemistry of surfaces
Nature of tribo-su

ADHESIVE WEAR
Sliding or Adhesive Wear
Sliding (or adhesive) wear occurs when surfaces
slide against each other.
In some engineering applications, surfaces slide in
air or without lubricant and the resulting wear is
termed as DRY SLIDING WEAR.
In most

Micro- and Nano-tribology
Reproduced mainly from
Engineering Tribology by
GW Stachowiak and AW Batchelor
and
Introduction to Tribology by
Bharat Bhushan
Nanotribology
A new branch of nanotechnology, nanotribology,
is now rapidly developing
Nanotribology

FATIGUE AND FRETTINGWEAR
Reproduced mainly from
Introduction to Tribology by
Bharat Bhushan
Fatigue Wear
- Repeated loading and unloading cycles
Sliding
Formation of surface cracks
Critical number of cycles
Wear results in the forms of microscopic
fragmen

Introduction
Heat Transfer correlations in pool boiling:
The four boiling regimes differ considerably in their character, and thus
different heat transfer relations need to be used for different boiling regimes.
In the natural convection boiling regime, b

Introduction
Analysis of heat exchangers:
An heat exchanger will be selected by an engineer
a) that will achieve a specified temperature change in a fluid stream of
known mass flow rate
Or
b) to predict the outlet temperatures of the hot and cold fluid st

Introduction
What is Heat Transfer?
Energy in transit due to temperature difference.
Thermodynamics tells us:
How much heat is transferred (Q)
How much work is done (W)
Final state of the system
Heat transfer tells us:
How (i.e. with what modes) Q is tran

Introduction
Emissive power, irradiation or radiosity of a real surface can be obtained
only after quantifying the spectral intensities as given by earlier equations.
Blackbody concept will be considered before going to find them.
1. A blackbody absorbs a

Introduction
Radiation heat transfer involves the transfer of heat by electromagnetic
radiation that arises due to the temperature of the body.
The energy of radiation field is transported by electromagnetic waves (or
alternatively photons).
The quantity

Introduction
Heat Conduction in solids is concerned with
Trying to find the temperature distribution for a certain situation or
configuration
Trying to find the rate at which heat flows in and out
for certain specified conditions, either in the steady s

Introduction
The final form of the boundary layer equations are given as:
Boundary Layer Similarity: The Normalized Boundary Layer Equations
It can be seen from above equations (momentum and energy) that, there is a
strong similarity exists.
These two equ

Introduction
Flow Boiling:
In flow boiling, the fluid is forced to move by an external source such as a
pump as it undergoes a phase-change process.
The boiling in this case exhibits the combined effects of convection and pool
boiling.
The flow boiling is

Introduction
Study of diffusion in a moving medium:
Consider a one-dimensional steady-state situation.
Mixture of two gases A and B.
Gases are moving at different velocities Va and Vb in the x-direction.
Molar densities ca and cb, and mole fractions xa an

Introduction
Heat exchangers are devices in which heat is transferred between two fluids
at different temperatures without any mixing of the fluids.
Applications:
1)
2)
3)
4)
5)
Heating
Air-conditioning systems
Chemical processing industries
Power plants

Introduction
Consider a laminar boundary layer flow that is driven by buoyancy forces.
Assumptions:
Steady, Laminar
Two-dimensional
Constant property conditions
(the gravity force acts in the negative x-direction)
Boundary layer approximations for forced

Introduction
Absorption, Reflection and Transmission by Real Surfaces
Radiation balance on the medium
Absorptivity
Reflectivity
Transmissivity
Conditions for which emission and absorption are equal will be considered.
Large, isothermal enclosure of surfac

CORROSIVE AND
OXIDATIVE WEAR
Reproduced mainly from
Engineering Tribology by
GW Stachowiak and
AW Batchelor
CORROSIVE WEAR
The surface chemical reactions are beneficial in preventing
adhesive wear
However , if unchecked, lead to a considerable loss of t

Introduction
Liquid or gas flow through pipes or ducts is commonly used in heating and
cooling applications.
The fluid in such applications is forced to flow by a fan or pump through a
tube that is sufficiently long to accomplish the desired heat transfer

Introduction
General Thermal Analysis:
In the absence of any work interactions (such as electric resistance heating),
the conservation of energy equation for the steady flow of a fluid in a tube
can be expressed as
where
Ti
Te
Q
Mean fluid temperatures at