Reduction of external and interior noise, also in view of compliance with legislation
In the past, technical progress made in noise reduction of vehicles was over-compensated by the growth of ground transportation. Given the predicted rate of traffic growth acceptable noise levels can be partly achieved through noise abatement measures (tunnels, barriers), but a substantial part of the reduction has to be achieved through reduction of the noise at source. For this reason the automotive and rail industry (worldwide as well as the European) has initiated a sustained research effort. The European Road Transport Research Advisory Council (ERTRAC) sets “noise reduction” as one of the major goals for future surface transport research: “Noise levels (must be) appropriate to individual locations including quiet zones. ... The research challenge is to deliver low emissions while also meeting ... vehicle performance,....”
The European Rail Research Advisory Council (ERRRAC) identifies very similar future efforts: “Simulation tools for noise assessment, the effectiveness of noise reduction measures .... are all areas for further study.... Deliverables include reduction in noise .... in addition to what will have been achieved through the FP6 projects SILENCE and QCITY.”
Thermodynamic principles require cooling systems for all present and future vehicle power trains. The stringent EU6 emission limits expected to come into effect in 2014 may require up to twice as high cooling power in road vehicles as compared to present technologies. Cooling systems are a major noise source, especially at standstill or stop and go traffic.
According to the latest European standards for interoperability of rail bound traffic within Europe the averaged sound pressure level LpAeq,T must not exceed 75 dB for both, electric power units and power units with internal combustion engines (EU 2005); ISO 3095 (CEN 2005). The research on noise prediction from mobile cooling units is widespread. Several groups in Europe are working on specific items to overcome the existing shortcomings and to extend the predictive methods to this complex application.
The ECOQUEST project is overcoming the fragmentation of research in this particular field. Since all major players in Europe are participating, the project brings the critical mass together which guarantees major achievements in the development and industrial utilization of noise prediction tools for mobile cooling units. Thus the contribution by ECOQUEST requires a European approach. The European dimension of the project is demonstrated by Tab. 3.1. In terms of noise levels, the consortium partners agree that for the locomotive applications, gains of the order of 6-8 dB(A) could be achieved through the thermal management and acoustic optimization procedures, including passive noise control at the source, that will be developed in the project. As for the automotive applications, which have been the subject of optimization for some time already, the consortium aims at a further reduction of 3-4 dB(A).