Component-based model to predict aerodynamic noise from high-speed trains

The aerodynamic noise produced by train pantographs and bogies is significant for typical speeds of modern high-speed trains. In order to reduce the negative environmental impact of high-speed train noise, the aerodynamic noise should be tackled in an early stage of the train design. In recent years, Computational Fluid Dynamics (CFD) and Computational AeroAcoustics (CAA) models have been developed in order to predict aerodynamic noise but they are very computationally-intensive. In this thesis, a semi-empirical component-based model is developed for quick prediction of the aerodynamic noise radiated by a high-speed train pantograph and bogie. The overall noise from the pantograph and bogie is obtained as the incoherent sum of the contributions predicted from the individual components. The model empirical constants are obtained using an experimental database built from data found in the literature and noise tests carried out during this work to evaluate the effect of different geometries and inflow conditions. For the pantograph, the struts are approximated as cylinders with a particular cross-section. To extend the available database, anechoic wind tunnel noise tests were carried out using cylinders with different cross-sections for different configurations. The predictions are compared with available noise measurements using a full-size pantograph showing good agreement. For the bogie case, the prediction model is developed by identifying each of the bogie components with simple shapes. Anechoic wind tunnel noise measurements were carried out using simple shapes to determine the empirical constants of the model. Additionally, scale train car body and bogie mock-ups were used, allowing for model validation and also providing useful information on the dependence on different factors of the aerodynamic noise generation in the bogie region. The results show the potential of the model to be used as an engineering tool to predict aerodynamic noise from train pantographs and bogies, allowing the effect of design modifications of components to be assessed and low-noise technology to be developed.