Unit 2 Aircraft Propulsion J Singh / MS Deepa Aeronautical

Refresher Mass Transfer Reviewed Working of a Gas Turbine Engine Thrust Equation for Turbojet, Turbofan, Turboprop, Ramjet Engine Quiz Tutorial posted on “aero2016” google group 8th August, All tutorials will be discussed in the class. Pl work out individually

Ideal (Brayton Cycle) Compression and Expansion are Reversible and Adiabatic Change of KE of working fluid between inlet and outlet of each component is negligible No pressure losses in the inlet, CC, exhaust ducting, ducting Working fluid has the same composition throughout the cycle Perfect gas with constant specific heats Mass flow of gas is constant throughout the cycle Heat transfer is complete, so that Temperature rise on cold side equals the temperature drop on hot side

Performance of Gas Turbine Cycles Forward speed and Altitude Specific Work output and Cycle Efficiency depend only on Pressure Ratio and Max Cycle Temperature

Refresher Tutorial posted on “aero2016” google group 8th August, All tutorials will be discussed in the class. Pl work out individually Question papers (class in-charge) Brayton Cycle: Efficiency & Specific Work output (depend only on…. and…..)

Cycle Analysis Heat Exchange Reheat Intercooled Numerical (V.Ganesan)

Factors affecting Thrust Velocity Temperature Altitude / Pressure Also refer class notes provided

Thrust Propelling Nozzle Outlet: Area (Ae) = 0.2150 m² Pressure (Pe) = 143.325 kPa Pressure (P0) = 101.325 kPa (ISA) Mass Flow (W2) = 70 kg/s Velocity (Vj) = 590 m/s Calculate Thrust (kN) at Sea Level Static Condition.

Thrust with Reheat Afterburner Propelling Nozzle Outlet: Area (Ae) = 0.2900m² Pressure (Pe) = 136.325 kPa Pressure (o) = 101.325 kPa Mass Flow (W2) = 70 kg/s Velocity (Vj) = 740 m/s Calculate Thrust (kN) at Sea Level Static Condition.

Thrust Augmentation There are occasions when maximum thrust from a basic gas turbine engine is inadequate, and some method of increasing the available thrust is required

Afterburning / Reheat This is employed to boost the thrust at various altitudes thus increasing aircraft performance. This is limited to short periods only, such as combat or take-off, due to the increased fuel consumption.

Water / Water-Methanol Injection This is employed to restore, or even boost, the thrust from a gas turbine operating from hot or high altitude airfields. This method is now normally limited to turboprop powered transport aircraft.

Aircraft engine schemes (1) Turboprop with two stage centrifugal compressor Twin-spool turboprop with axial compressor

Aircraft engine schemes (2) Single spool turbojet with axial compressor Turboshaft with twin-spool gas generator Twin-spool bypass

Aircraft engine schemes (3) Triple spool turbofan (separate exhausts) Unducted (aft)fan or propfan