Train pass-by noise source characterization and separation tools for cost-effective vehicle certification

Periodic Reporting for period 2 - TRANSIT (Train pass-by noise source characterization and separation tools for cost-effective vehicle certification)

Okres sprawozdawczy: 2021-06-01 do 2023-02-28

Train designs should no longer have to compromise comfort for speed. Improving passenger ride comfort and reducing the environmental impact of railway vehicles is a priority, with noise control topping the list. However, certification and authorisation procedures are currently costly and time-consuming, while the application of complex materials to reduce vehicles' weight and fulfil energy efficiency needs affects noise insulation. The EU-funded TRANSIT project is a consortium of universities, research institutions and companies specialising in railway noise and vibration, aiming to provide the railway sector with instruments and methods that will reduce interior noise in vehicles, at the same time developing advanced methods that will facilitate virtual testing and lead to more economical vehicle certification and authorisation procedures. TRANSIT will create new methods and tools that will give a better understanding and quantification of the contribution of the different sources to the total train pass-by noise. These methods and tools will reduce the costs and efforts required for certification testing, greater comparability and reproducibility of test results and ultimately improved competitiveness for the EU rail industry and increased social acceptance of railways leading to modal shift.

TRANSIT aims at realizing a break-through in virtual testing and virtual certification by developing validated source characterization, exterior noise simulation models, and measurement-based separation techniques.

The methods and tools developed in TRANSIT have been evaluated in measurement campaigns, leading to several significant steps towards virtual testing and virtual certification. Source characterization methods including installation effects and geometric uncertainties are developed for roof and under-vehicle sources, showing a good agreement with measurement results. Novel methods to estimate source directivity from (high-speed) pass-by measurements are proposed and tested, leading to promising results. For wheel-rail noise separation a method for roughness separation is proposed and demonstrated, eliminating the need to perform rail roughness measurements, which minimizes track access time. The methods proposed in TRANSIT will now be further developed such that these can be employed within the railway community. These innovations include improved acoustic performance of air conditioning ducts and panel structures with innovative materials. These innovations will contribute towards an decreased time and effort require for vehicle certification and authorization by use of virtual testing. This will speed up the design of trains with improved passenger ride comfort, reduced interior noise and reduced environmental impact.

To reach the aforementioned aim of TRANSIT, five high level objectives have been specified. These five high level objectives have been mapped onto 6 work packages. In section 1.2 the work carried out per work package is presented, this section will continue with an update in the context of the high level objectives.

Reduce rail vehicle noise certification lead time and costs, and lower operator’s track occupation requirement for testing by providing accurate virtual certification tools. Validated procedures for source characterization have been developed and tested on generic sources. Together with FINE-2, two additional test objects have been selected, and characterized. Different calculation models for these tools have been compared. [WP1]

Reduce the need for a TSI-compliant track by developing and demonstrating accurate separation and transposition techniques. Separation methods (PBA-based, TWINS-based and ATPA-based) have been enhanced, tested at MdM and in measurement campaigns with FINE-2. Successful tests for separating track and wheel contributions for the various test vehicle, as well as wheel/rail roughness separation. Transposition techniques have been assessed with a positive outcome. [WP3]

Derive a more precise and better-founded definition of acoustic requirements for equipment suppliers, reducing time and cost. Equivalent models to describe source sound power and directivity and the corresponding measurement techniques are developed, based on existing standards (e.g. ISO 3744) as far as possible. The validation of the methods on railway acoustic sources have been assessed as part of the measurement campaign.. [WP1]

Improve source quantification for noise mapping and a more accurate assessment of noise abatement measures. Methods for pass-by source separation and track-vehicle separation have been developed and evaluated during the measurement campaigns with FINE-2. The experimental validation, therefore, includes tests on metro train (October 2021), regional train (March 2022), high-speed train (Sept 2022). Estimates for rolling noise, equipment noise, traction noise and aerodynamic noise contributions have been successfully derived and pass-by source separation methods have been validated. [WP2&WP3]

Enable lighter vehicles, thus lower energy consumption, while maintaining high levels of interior acoustic comfort. Two material design concepts have been selected by FINE-2 and optimized by TRANSIT. One of the concepts (a sound reduction device) performs very promising in simulation. Small-scale lab experiments have been performed in an impedance tube and in a duct section, the performance of the sound reduction device does not meet the expected performance based on the simulations. [WP4]

The developed methods, experiments and results have been presented and discussed at the TRANSIT final conference and others.

The research conducted in the TRANSIT project has made progress beyond the state-of-the-art in several areas related to, amongst others, reducing rail vehicle noise and improving acoustic comfort.
TRANSIT’s results will contribute to faster (virtual) certification by implementing the developed methods into tools that can characterize the source of noise. Various methods to do so have been compared. The more precise and better-founded definitions of acoustic requirements for suppliers will reduce time and costs. The validation of the used methods, using equivalent models, have been assessed as part of the TRANSIT + FINE-2 measurement campaign.
Using the developed separation and transposition techniques, the need for a TSI-compliant track is reduced and will reduce certification workload. The separation techniques have shown positive outcomes towards separating track (roughness) and wheel contributions.
Two material design concepts (selected by FINE-2, optimized by TRANSIT) have been simulated and assessed in small-scale lab experiments. These sound reduction devices have been found to contribute to lighter vehicles, thus lower energy consumption, while maintaining high levels of interior acoustic comfort.

Overall, the progress made in the TRANSIT project contributes to predicting noise and vibration, characterizing their sources, and, thereby, addressing the objectives of the Shift2Rail R&I Programme. The potential impacts include reducing certification lead time and costs, improving acoustic requirements definition, enabling more accurate noise assessment, and enhancing interior acoustic comfort in lighter rail vehicles.

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Periodic Reporting for period 2 - TRANSIT (Train pass-by noise source characterization and separation tools for cost-effective vehicle certification)

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