Integration of core engine for a genset with clutch Rolls-Royce Solutions Liège SA

Abstract

The growing need to reduce the Total Cost of Ownership of industrial power systems and to accommodate alternative fuels such as natural gas, HVO and hydrogen is driving the modernisation of existing Uninterruptible Power Supply systems. In this context, Rolls-Royce Solutions Liège is developing a new generation of its UPS system, the Kinetic Energy Storage System (KESS). In this new architecture, the kinetic accumulator is removed from the main drivetrain. The short-term energy storage function is taken over by a standalone flywheel operating under vacuum with magnetic bearings, which provides a longer ride-through time than the integrated accumulator. The new system consists of a genset comprising an MTU core engine, an electromagnetic clutch, a flywheel and a synchronous alternator, combined with this standalone flywheel energy storage unit.

This thesis presents the mechanical design and structural validation of the genset. The flywheel is dimensioned to meet an inertia requirement of 561 kg.m^2 and validated by finite element analysis under three load cases, with a maximum von Mises stress of 234 MPa remaining below the yield strength of S355J2. The taper lock, the electromagnetic clutch and the bearings are selected based on the requirements of the application. The intermediate shafts are dimensioned based on both static and dynamic. The dynamic safety is assessed using ROSS, confirming that the first critical speed at 2253 RPM is safely above the operating speeds. Finally, the housing is validated through an iterative structural and modal analysis. Geometric modifications are applied to meet the structural requirements, and the modal analysis confirms a safety margin of 26.3% on the third axial mode with respect to the operating frequency of 30 Hz