Rotordynamic Design Studies of Medium Thrust Class Twin Spool Engine

Rotordynamic design studies are an important part of gas turbine design and development since there is a direct influence on the structural integrity, health and fatigue life of rotating as well as static components. Rotordynamic analysis primarily involves the estimation of critical speeds, mode shapes, strain energy distribution, kinetic energy distribution and response to unbalance. The important parameters in design studies include number of bearings, location of bearings, geometric properties of rotor, bearing support design, stiffness and damping in bearing planes. The design procedure is iterative and constraints imposed by the layout should be considered during design modification. In this work, parametric study of various configurations of the rotor-bearing system of a medium thrust class turbofan engine have been presented. The modelling and analysis have been performed in DyRoBeS Rotor software using Timoshenko beam element. The chosen general arrangements are compared against each other to arrive at the optimum configuration from the point of view of overall dynamic behaviour.