(Sherwin, Keith & Michael, Horsley, 1996). Fuel is mixed with air and ignited this is where energy is added to the gas stream in the combustor. The temperature increases combustion of the fuel in the high pressure environment of the combustor, the products of the combustion are forced into the turbine section. Directed through a nozzle over the turbine’s blades is the high volume and velocity of the gas flow this spins the turbine which powers the compressor and, in some other turbines, this drives their mechanical output. The reduction in the pressure and temperature of the exhaust gas comes from the energy given up to the turbine moreover, energy can also be extracted in the form of shaft power, compressed air temperature can be used to power ships, trains, aircraft, tanks, and generators. (Husain, 2010) Task 1 There are 5 basic models of a turbo fan high bypass engine. This involves the first stage compressor that is drastically enlarged for the provision of bypass airflow around that core of the engine. This also allows for a significant amount of thrust. Turbo Jet Engine Air Inlet Combustion Chambers Turbine Propelling Nozzle Compressor Diagram of turbojet engine As depicted in the diagram above, a Turbojet engine comprises of the intake, compression, combustion, turbine and exhaust sections. The compression chamber directs the incoming air into the combustion chamber at relatively a high velocity. The combustion chamber is equipped with igniters and nozzles that enable combustion. During this process of combustion, the expanding gas is then utilized in rotating the gas turbine and keeps the engine operational as the compressor is driven through the shaft (Turbine Engines). nc = T2 – T1 T2a – T1 and n4 = T3 – T4a T3 – T4 Applying the steady flow energy equation, v20 - v21 = 2(h1 – h0) Change in kinetic energy and change in enthalpy: v20 = 2cp(T1 – T0) Work output from the turbine balances the work input into the compressor, hence equating change in enthalpy results in: cp(T2a – T1) = cp(T3 – T4a) T2a – T1 = T3 – T4a [cp is constant] Airflow through the nozzle: v25 = 2cp(h4a – h5) Since velocity is constant, v4 = v1 ? 0 Exit velocity at the nozzle: v25 = 2cp(T4a – T5) Therefore, Thrust, F = mvc - mv Thrust = m(vc – v) The net exhaust speed of turbofans is much lower than that of a turbojet and as a result, this makes them much more efficient at subsonic speeds than turbojets, also they are more efficient at supersonic speeds up to Mach 1.6. Turbofans are the jet engines that are used in all currently manufactured commercial jet aircraft. During the intake phase in the turbofan engine, the pressure, temperature and volume of the gases remain constant. The fan is installed at the inlet of the engine to increase the amount of air flowing through the engine at any given time. Part of the inlet airflow is not directed toward the compressor, combustor, and turbine during this process, but is rather bypassed through a duct, which ends in a nozzle. This provides thrust through exchange of momentum with the airframe, because the gas leaves the nozzle at a speed that is higher than the intake velocity. Their high efficiency and relative quietness in operation is the main reason their high efficiency and relative quietness in operation is the main they use them commercially, many military jet aircraft also make use of turbofans.