Air Compressors
Introduction; Classification; Application of compressors and use of compressed air in industry
and other places; Complete representation of compression process on P-v and T-s coordinates
with detailed description of areas representing total work done and polytropic work done; Areas
representing energy lost in internal friction, energy carried away by cooling water and extra flow
work on T-s coordinates for un-cooled and cooled compression; Definitions of isentropic,
polytropic and isothermal efficiencies and their representation in terms of ratio of areas
representing various energy transfers on T-s coordinates.
Reciprocating Air Compressors
Single stage single acting reciprocating compressor (with and without clearance volume):
construction, operation, work input and best value of index of compression, heat rejected to
cooling medium, isothermal, overall thermal, isentropic, polytropic, mechanical, and clearance
volumetric efficiency, overall volumetric efficiency, effect of various parameters on volumetric
efficiency, free air delivery; Multistage compressors: purpose and advantages, construction and
operation, work input, heat rejected in intercoolers, minimum work input, optimum pressure
ratio, isothermal, overall thermal, isentropic, polytropic and mechanical efficiency.
Positive Displacement Rotary Compressors
Introduction; Classification; Comparison of rotary compressors with reciprocating compressors;
Construction, operation, work input and efficiency of rotary compressors like roots blower,
Lysholm compressor and Vane type Blower.
Centrifugal Compressors
Construction and operation; Applications of Steady Flow Energy Equation and thermodynamics
of dynamic compressors; Stagnation and static values of pressure, Temperature and enthalpy for
flow through dynamic machines; Complete thermodynamic analysis of centrifugal compressor
stage; Polytropic, isentropic and isothermal efficiencies; Complete representation of compression
process starting from ambient air flow through suction pipe, Impeller, Diffuser and finally to
delivery pipe on T-S coordinates; Pre-guide vanes and pre-whirl; Slip factor; Power input factor;
Various modes of energy transfer in impeller and diffuser; Energy transfer in backward, forward
and radial vanes; Pressure coefficient as a function of slip factor; Efficiency and out-coming
velocity profile from the impeller; Derivation of non-dimensional parameters for plotting
compressor characteristics; Centrifugal compressor characteristic curves; Surging and choking in
centrifugal compressors.
Axial Flow Compressors
Different components of axial flow compressor and their arrangement; Working; Discussion on
flow passages and simple theory of aerofoil blading; Angle of attack; coefficients of lift and drag;
Turbine versus compressor blades; Velocity vector; Vector diagrams; Thermodynamic analysis
and power calculations; Modes of energy transfer in rotor and stator blade flow passages; Detailed
discussion on work done factor, degree of reaction, blade efficiency and their derivations;
Isentropic, polytropic and isothermal efficiencies; Surging, Choking and Stalling in axial flow
compressors; Comparison of axial flow compressor with centrifugal compressor; Field of
application of axial flow compressors.
Gas Turbines
Classification on the basis of system of operation (open and closed cycles) and on the basis of
combustion (at constant volume or constant pressure); Comparison of open and closed cycles;
Comparison of gas turbine with IC engine; Fields of application of gas turbines; Position of gas
turbine in power industry; Thermodynamics of constant pressure gas turbine cycle (Brayton
cycle); Calculation of net output, work ratio and thermal efficiency of ideal and actual cycles;
Cycle air rate, temperature ratio; Effect of changes in specific heat and that of mass of fuel on
power and efficiency; Multistage compression and expansion; Dual Turbine system; Series and
parallel arrangements; Closed and semi-closed gas turbine cycle; Requirements of a gas turbine
combustion chamber; Gas turbine fuels.
Jet Propulsion
Principle of jet propulsion; Description of different types of jet propulsion system like rockets and
thermal jet engines like (i) Athodyds (ramjet and pulsejet), (ii) Turbojet engine, (iii) Turboprop
engine. Thermodynamics of turbojet engine components; Types of rocket motors (e.g. solid
propellant and liquid propellant systems); Various common propellant combinations (i.e. fuels)
used in rocket motors; Cooling of rockets; Advantages and disadvantages of jet propulsion over
propulsion systems.