Thivant M.,Vibratec |
Andersson P.B.U.,Chalmers University of Technology |
Guyader J.-L.,INSA Lyon
Acta Acustica united with Acustica
This paper proposes the intensity potential approach for prediction of high-frequency sound power radiation.The approach is based on the Helmholtz decomposition of the vector field of time-averaged sound intensity into its irrotational and rotational components. The local power balance in a lossless medium is expressed in terms of the irrotational component only, and results in the Poisson equation for a scalar intensity potential of this component only. The approach gives an exact expression for the sound power through any closed surface in terms of the irrotational component, provided that the boundary conditions are correct. The approach is evaluated by exploring the two intensity components in three canonical examples, and by comparison to measured data with special focus on directivity aspects. It is concluded that the intensity potential approach is relevant, in particular for high-frequency sound fields from multiple sources that are uncorrelated and broadbanded. However, the intensity is generally overestimated in the shadow zones and underestimated in the directly exposed regions. Further, peaks in narrow frequency bands associated with interference of waves are ignored. © S. Hirzel Verlag. Source
Dupont J.-B.,Vibratec |
Lanfranchi V.,CNRS Electromechanical Laboratory of Compiegne
Proceedings - 2014 International Conference on Electrical Machines, ICEM 2014
A simulation methodology is described in this paper. It consists in a multi-physical approach to simulate the dynamic forces and noise radiated by electric motors. The principle is first to calculate the excitation due to electromagnetic phenomena using an electromagnetic finite element solver. This excitation is then projected onto the structure mesh of the stator in order to calculate its dynamic response and the radiated sound power. This paper focuses on the possibility to include in this simulation the defects related to a real machine such as static eccentricity or dynamic eccentricity in order to enhance its accuracy. The excitations are analyzed in terms of excitation content (frequency content and spatial distribution) and the consequences on the sound power radiated by the machine are discussed. © 2014 IEEE. Source
Agency: Cordis | Branch: FP7 | Program: BSG-SME | Phase: SME-2012-1 | Award Amount: 1.51M | Year: 2012
Recent trends in European housing and demographics have had a significant effect on the European domestic appliances sector, in particular for laundry. A growth in single occupancy, an increase in multi-dwelling buildings (flats) and a fall in household floor space have all driven an increase in the purchase of combined washer-dryers, growing at 9% p.a. However, washer-dryers are inefficient, using as much as 50% more energy to wash and dry a load than separate systems. This is a concern both for energy consumption and cost for the user - estimated 15 million washer-dryers consume 18 TWh of electricity worth 300m and indirectly emit 10,000 tonnes of CO2 each year. As well as energy efficiency, washer-dryers also have practical limitations. Due to the small drum size of the machine compared to a dedicated tumble dryer, it is not possible to dry a full wash load in one go, adding to cost and significantly reducing convenience. LoWash will address these issues by creating a highly energy-efficient machine capable drying a complete wash load without user intervention. It will achieve this by combing an innovative hydraulic load balancing drum with a unique passive/active heat pump drying chain to create a washer-dryer capable of washing and drying a complete 7kg load without removing any of it from the machine. It will do this using <50% of the energy required by current washer dryers. Realising this vision would provide a 34m market opportunity to our consortium for washer-dryers. The technology can also be applied to standalone washing machines and tumble driers, which would more than double the market potential. In the process, LoWash will save 16 GWh of electricity over 5 years.
Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: SST.2011.2.5-1. | Award Amount: 3.21M | Year: 2011
ACOUTRAIN will simplify and improve the acoustic certification process of new rolling stock, in particular relating to the TSI Noise. Today the need of conformity assessment for a new vehicle according to the TSI Noise represents a significant element of both cost and time to market due to the need to carry out expensive and time consuming tests. The goal of the proposed project is to speed up the product authorisation by introducing some elements of virtual testing while retaining the same degree of reliability and accuracy. A successful simplification of the TSI conformity assessment process would result in a strengthening of the competitiveness of the European railway sector. The risk of not developing such a simplification would be that the expense of excessive certification of new products could hamper the introduction of new innovations. The major outcome of the ACOUTRAIN project will be a new certification process including some elements of virtual testing. This will be ready for inclusion in the next full revision of the TSI Noise, planned in 2013. The R&D work program will be implemented with the following objectives: WP1- establishment of procedures for a virtual certification of acoustic performances of freight and passenger trains; WP2 -an improvement and harmonization of the rolling noise characterization process; WP3 -establishment of methodologies to measure other noises sources; WP4 - a methodology to validate global tools for pass-by noise and standstill noise predictions so that they can be used as part of future certification; and WP5 - a validation of the procedure range for the virtual noise certification. A significant part of the project is dedicated to the relationship with the Notify Bodies and Authorities to ensure that the objectives of the project are well connected with their expectations.
Nielsen J.C.O.,Chalmers University of Technology |
Mirza A.,Bombardier |
Cervello S.,Lucchini RS S.p.A. |
Huber P.,PROSE GmbH |
And 3 more authors.
International Journal of Rail Transportation
Wheel out-of-roundness (OOR) and unsprung mass are key railway vehicle parameters influencing the dynamic wheel‒rail contact loads and inducing ground-borne vibration. For a given combination of vehicle speed, track/soil conditions and wheel/rail irregularity level, reducing the unsprung mass leads to a reduction in contact loads and vibration at frequencies above the resonance of the wheelset on the primary suspension. Guidelines for reducing unsprung mass are presented, including alternative designs for the wheelset and the suspension of the mechanical drive system. For locomotives and powered bogies, the potential for reduced vibration level is 2-4 dB by improving the drive suspension design. Based on an extensive field measurement campaign, where the influence of several different types of vehicle on vibration level was measured, it was found that the maximum vibration levels were generated by freight locomotives. For several freight locomotives of the same type, a high statistical variance (up to 20 dB) in measured vibration level was observed indicating a significant spread in wheel tread conditions and OOR. Early detection of out-of-round wheels and corrective wheel maintenance are important measures to reduce vibration levels. © 2015 Taylor & Francis. Source