1 Effect of Pressure Recovery on Triple Spool Turbofan Engine Performance Eslam Said Abdelghany 3 , Ahmed F. El-Sayed 2, Mahmoud A. Fouad 1 and Essam E. Khalil 4 , 1 Professor of Mechanical Eng. Cairo University, Egypt 2 Professor of Mechanical Eng. Zagazig University, Egypt 3 Inst. of Aviation Eng.Cairo, Egypt 4 Professor of Mechanical Engineering, Cairo University, Egypt, AIAA Fellow, khalile1@asme.org ABSTRACT Present and future studies in jet engine design appropriate for wide-body in civil aircrafts (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. 1. INTRODUCTION There are five basic components of a gas turbine engine; namely, intake, fan/compressor(s), combustion chamber, turbine(s) and nozzle(s). Air that enters the intake of the engine is firstly compressed; next fuel is injected/burned in the combustion chamber finally the generated hot gases drive the turbine and leave the engine through the nozzle producing a high jet speed[1]. Turbofan engines have many advantages over others like turbojet and turboprop engines. These advantages include higher thrust, higher propulsive efficiency, lower specific fuel consumption (SFC), and lower emission and lower noise; [2] and [3]. Turbofan operates at altitudes up to 86000 ft. Three spool engines are selected today for many aircrafts [4]. The intake of an aircraft engine is an important component which affects not only the propulsive characteristics but also the aerodynamic characteristics of the aircraft. The intake delivers the free stream air to the engine. In each phase of the flight condition corresponding to different flow types ranging from subsonic to supersonic speeds, the intake must provide an appropriate amount of the airflow to the engine. It retards the incoming flow and converts its kinetic energy into pressure. Although it does no work on the flow itself, it is responsible for the quality of the air at the face of the compressor which requires high total pressure energy and minimum distortion. In addition, since the inlet is included in the wetted area of the air vehicle, its shape and location directly affect the aerodynamic forces on the vehicle. Figure (1), gives the flow pattern in a subsonic air intake for a low speed, design speed, and high speed. the goal of good intake