Pressure Recovery Effect on Triple Spool Turbofan Engine Performance

摘要

Present and future studies in jet engine design appropriate tor wide-body in civil aircrarts (such as the Airbus 380 and Boeing Dream liner 787) is high bypass turbofan (HBPT) engines. Turbofan engines which are categorized of more than ten types dominated in both civil and military aircrafts. This work is devoted to performance analysis of an unmixed triple spool HBPR Turbofan engine; namely, Trent 700. Two parameters are examined here; namely, pressure recovery factor and percentage of air bleed from high pressure compressor. The first parameter is directly influenced by the flight path of aircraft during takeoff and climb. In such flight phases both aircraft wing and engine are susceptible to high angle of attack and possible air separation. Pressure recovery attains a minimum value at takeoff and a maximum value at cruise phase. Pressure recovery varies from 0.92 to 0.99. Such reasonable variation has greatly influence thermodynamic characteristics of engine cycle. Moreover, it influences its thermal, propulsive and overall efficiencies together with its specific thrust. Both takeoff and cruise conditions (flight Mach number of 0.82 and 12km altitude) are examined. Moreover, bleed air of 8 % from second compressor to cool first (HP) and second (IP) turbines of Trent enabled engine designers to achieve a maximum temperature of 1543 Kelvin. The effect of the Mach number variation (from 0 to 1) on the performance of Trent 700 is examined in details using computer program matlab-7 to simulate and analyze thermal cycle of the engine. The results showed specific thrust increase by 5%, thrust specific fuel consumption decrease by 4%, thermal efficiency increase, propulsive efficiency increase and overall efficiency increase. It was studied effect of angle of attack (40, 30, 20, 10, and 0) degree and altitude of aircraft on pressure recovery factor value. Using computational fluid dynamics software FLUENT ® and choosing The Spalart-Allmaras turbulence model to simulate turbofan intake.