TURBO-DOUBLE FAN ENGINE

Abstract

The paper analyzes the thermodynamic scheme of a derived engine from the reference tubofan CFM56-7B27 (Snecma&General Electric), used by Boeing 737-300, C-40 Clipper, P-8 Poseidon, Project Wedgetail. This engine thermodynamic scheme has two fans which split the fan based air flow in two propulsive air jets. The intention of this work is to find how they are changing some takeoff conditions (sea level) such as the thrust, the fuel consumption, the propulsion jets velocities, and the evaluation of the jets noise by using the comparison of the radial relative flows velocities of the concentric jets for the turbo-double fan and the basic turbofan. The numerical results were obtained following two ways of cycle modification: 1st way maintained the by pass ratio and the maximum compression ratio, and they were imposed the fan’s compression ratios in the range 1.4 to 1.8; 2nd way maintained the maximum compression ratio and they were imposed the propulsion jets velocities to 465m/s, 308 m/s and (200 to 240) m/s. The numerical results showed that 1st way provides few advantages such as a slight increase of the thrust and a minor reduction of the specific fuel consumption [kg/daN/h], but the 2nd way might conduct to a major reduction of the specific fuel consumption [kg/daN/h], of about 30%, even the thrust decrease with about 20%.