Thermodynamic and Rotordynamic Assessment of Conventional and Ultra-High Bypass Ratio Engines

Abstract

Due to the economical aspiration to increase the efficiency and several ecological regulations to reduce CO2 and noise emissions, aircraft and engine manufacturer have to increase the bypass ratio of gas turbines. But, the higher the bypass ratio of a gas turbine is the larger the rotating masses are. Thus, concerning the system stability due to the change of the eigenbehavior of the aircraft in its structure, the dynamic influences of gyroscopic moments as the consequence of the angular momentum of the engine are an uncertainty and need to be investigated carefully. This paper compares two gas turbines, a conventional one with a bypass ratio of 5 and one with an ultra-high bypass ratio of 17. Two different approaches are presented. On the one hand, a comparison regarding the thermodynamical cycle process, on the other hand, using a multibody formulation, a model of a Coanda wing with each of the engines mounted over the airfoil is presented. The analysis conducts the structural coupling and dynamical influences on the wing structure arising during their operation at specific design points. The comparison of the dynamic influences should show which structural effects on the wing structure come along with the trade-off due to increased thermodynamic efficiency.