Gas Turbines & Jet Propulsion
Fundamentals of gas Dynamics. Conservation of mass, Momentum and energy equations for one dimensional steady state compressible fluid flow. Sonic velocity, Mach number, Mach cone, Mach angle. Stagnation temperature, pressure and enthalpy. Isentropic flow through a passage of varying cross section. Choking in isentropic flow. Operations of nozzles under varying pressure ratios - Converging nozzles - Converging - Diverging nozzles. Adiabatic flow with frictions in constant area ducts. Fanno lines, Fanno relations for perfect gases. Concept of Rayleigh lines. Normal shock. Strength of shock wave and shocks in converging diverging nozzles.Centrifugal and axial flow compressors - Centrifugal compressor construction, flow process on T-S diagram, velocity diagram and Euler s work. Slip factor and its effect on work input. Actual work input, Dimensionless parameters of centrifugal compressors pre-whirl losses in centrifugal compressor, surging. Axial flow compressor - constructional details, velocity triangles and work done. Pressure rise and aerodynamic force in flow with the without friction. Cascade efficiency, Dimensionless parameters, losses in axial compressor stage choking flow. Stalling characteristics of centrifugal and axial flow compressor. Comparison between centrifugal and axial flow compressors. Compressor materials.Gas turbine cycles, Simple open cycle Brayton cycle Gas turbine - Thermal efficiency. Actual Brayton cycle - its thermal efficiency. Cycle air rate, work ratio optimum pressure ratio. Means of improving the efficiency and specific output. Gas turbine with reheat, inter-cooling. Regeneration. Effect of these on efficiency effect of operating variables on thermal efficiency, air rate and work ratio, water injection. Closed cycle gas turbines semi-cooling cycle gas turbine. Advantages and disadvantages of gas turbine over steam turbine and petrol and diesel engines.Impulse and reaction turbines - Introduction, A single impulse and reaction stage, Multistage machines, Velocity triangles. Work output, Blade loading and flow coefficients, Blade and stage efficiencies. Maximum utilization factor, velocity, pressure compounding reaction turbines, Blade to gas speed ratio losses and efficiencies performance graphs.Combustion systems - Introduction, combustion theory, factors affecting combustion chamber design and performance form of combustion systems. Requirement of combustion chamber process of combustion. Combustion chamber geometry mixing and dilution. Combustion chamber arrangements, Fuels for gas turbines, Flame tube cooling, Fuel injection and ignition. Fuel for gas turbine and pollution problems. Materials for gas turbines factors influencing selection of materials. Requirements for high temperature materials - Some typical materials. Blade cooling - Recent developments and typical applications.Jet propulsion cycles - Introduction, Ramjet, Pulse jet, Turbo prop - Turbojet, Turbofan engines, Scramjet. Thrust equations, specific thrusts, Thrust augmentation, Efficiencies, Parameters affecting performance ; thrust augmentation fuels for jet engines. Rocket propulsion - Introduction, classification. Chemical Rockets liquid propellants. Solid propellant, Nuclear rocket engines. Ion rocket, magneto plasma rocket engines, Solar rocket engines, staging of rockets, applications of rockets.