India seeks to develop its own fighter aircraft engine in a market dominated by global players
Air Cmde Trilok Chand (retd)
Aero engine forms the most important and vital part of a flying machine. Turboprop engine of the older variety continues to be used in some of the newer generations of transport aircraft. All fighter aircraft employ turbojet or turbofan engines usually with afterburner system.
Engineers continue to strive for the newer designs with an enhanced thrust to weight ratio and very little thermal signatures for providing stealth features to the fighter aircraft. The conventional aero engine invariably has an air intake which usually forms part of the airframe of the aircraft, a set of compressors, a set of combustion chambers, another set of turbines and a jet nozzle system.
Various other components involved in engine fuel system, engine oil system, starting system, afterburner system, thrust vectoring system, cooling system and afterburner system are also parts of the engine and airframe of the aircraft. Many of these systems are driven by the engine itself through an accessory gearbox mounted on the engine. Scramjet engines are also under development to power hypersonic craft. These engines have no moving parts. Design features of the components of the modern fighter aircraft jet engine vary for different types of aircraft. This feature has been implemented in the design of the Tejas aircraft to some extent.
Air Intake: The airframe i.e. the body of the aircraft provides for the supply of the air to the compressor of the engine for feeding to a combustion chamber and cooling systems. Unlike older designs, the air intake of the modern AC is made serpentine in shape. This camouflages the compressor blades from the incidence of the radar electromagnetic waves and reflection to the receiver. A poor reflection of these waves adds to the stealth features of the aircraft.
Compressor: The two principal types of compressors currently being used in gas turbine aircraft engines are centrifugal flow and axial flow. The compressor spools and blades are made of special corrosion resistant, light but strong materials. Air compression is carried out by several stages of compressor blades, the size and the number of the compressor stages depend upon the power generation requirements of the aero engine. Indian Gas Turbine Research Establishment (GTRE) GTX-35 VS Kaveri engine is an axial compressor with two spools; six stage high-pressure stages along with variable inlet guide vanes and three-stage low-pressure stages with transonic blades arrangement.
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