(a)
Hot Section Module Components-The hot section module consists of the following components: combustion liner, stage one nozzle assembly, stages one and two gas generator turbine rotor, and the gas generator stator.
1.
Combustion Liner-The combustion liner is where combustion occurs and energy, in the form of gas pressure, is directed aft to act upon two separate turbine sections (Ng and Np). It also houses twelve fuel injectors, two primer nozzles, and two igniters. Two counter rotating air vortexes swirl over each injector. The injectors spray preheated fuel at high pressure in a 32 degree duplex cone pattern that rotates fuel spray opposite the vortex air. This process yields nearly complete atomization, ensuring excellent fuel economy and a low smoke level in the exhaust.
2.
Stage 1 Nozzle-The stage 1 nozzle directs gas pressure upon the stage 1 GG rotor, a second nozzle, located within the stator, directs gas pressure onto the stage 2 GG rotors. The GG rotors drive the compressor and engine AGB components as driven by the PTO gear and radial drive shaft. About 75% of the total combustion energy is extracted by the GG rotors to self sustain the engine. The remaining combustion energy powers the helicopter through the power turbine. The GG rotors operate in an extreme environment of high temperature and centrifugal loads. It is critical to respect the engine operating limits to prolong the life of the GG rotors. Due to the nature of the environment in which the GG rotors operate, permanent stresses accumulate within the rotors and they are replaced at established intervals in accordance with history recorder data.
3.
Stage 1 Rotor-Overall power production is limited mostly due to thermal reasons. A thermal barrier exists within the confines of current metals and cooling technology, and engineers strive to produce maximum power without damaging the engines components. Cooling air must be present prior to starting the engine, and remain present during engine operation. Primary air enters the combustion chamber to support combustion for power production (approximately 33% of the total CDP). Secondary air is used to cool hot section components (approximately 66% of the total CDP).
4.
Gas Generator Turbine Stator-P3 air protects the hot section components from heat destruction by diluting combustion gasses to reduce heat, and by maintaining a protective boundary layer between the flame and the metal. P3 air is also directed inside the hot section components to conduct heat away from the components. The interruption of P3 air (as in a compressor stall) can stress or damage the hot section components. TGT/T4.5 represents the temperature at the gas generator output, which is the same as the power turbine temperature. This temperature is limited to 850 oC by the ECU. 850o C at T4.5 equates to about 1700o C - 1800o C within the combustion chamber. A malfunction of the
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