Aerodynamic and Acoustic Optimization of Axial Fans for Locomotive Cooling Systems

Abstract

The aerodynamic and acoustic performance of a locomotive cooling module is optimized by a new design strategy for the fan unit. The fan selection or development of the cooling modules is usually based on the specific design point but without consideration of installation effects. The new approach considers the fan development in a more integrated manner. A simplified 1:4 model of the cooling system is constructed and used for system analysis, numerical flow simulations, and experimental validation. The subsequent fan and guide vane optimization is based on numerical simulations embedded in an optimization algorithm taking installation effects into account. The noise emitted by the fan is addressed by a smoothed inflow velocity profile, a new blade sweep strategy, the reduction of secondary flows, and the reduction of fan size and rotational speed. The optimized fan unit is then integrated into the non-simplified full-scale system. Experiments reveal an energy saving of 20% and an overall sound power level reduction of 6 dB with even higher reduction of the tone at blade passing frequency. All results are discussed with respect to transferability to other cooling modules. It is found that a set of general design recommendations originates from this work, whereas the optimization loops would need to be repeated for other cooling module types.