LEAM

Acoustical and Mechanical Engineering Laboratory

General description of the activity

The Acoustical and Mechanical Engineering Laboratory is a research centre of the Department of Mechanical Engineering at the Technical University of Catalonia, located in Terrassa.  The center expertise area is the development of noise control techniques focussing both in basic research in acoustics and vibration, and in technology transfer to industry. LEAM has developed technological innovation projects for the industry and public administrations, sometimes as a part of a PhD thesis. The main research areas of LEAM within noise control are:

• Active Noise Control: A  technique that aims to reduce unwanted noise by destructive interference with an additional acoustic field (right), generated electronically.  LEAM is working towards the application of this technique in ducts as a commercial applications (for air conditioning installations), and on the optimization and application of local noise control techniques.
• Environmental Acoustics & Vibrations: LEAM is developing statistical sampling strategies to map noise in urban areas by means of direct measurements. Related to the environmental impact of vibrations, LEAM is working towards the creation of a model of the generation, propagation, and transmission into buildings of train generated vibrations.
• Measurement systems to identify source in noisy environments: Among others, LEAM is developing a system to monitoring aircraft noise in presence of background noise using microphone arrays.
• Noise Emission Control: LEAM applies the knowledge generated in all the other research lines to solve industrial problems related to noise and vibrations control.

Specific areas of research energy field

Wind turbine has been rated as more annoying than transportation noise or industrial noise at comparable noise levels, and the proportion of people annoyed increases more rapidly with the sound pressure level than for the other sources. It is true that wind turbine noise currently affects a relative small portion of the population but the number of people exposed is increasing rapidly and disturbance from wind turbines may be an obstacle for large-scale production. Nowadays mechanical noise in wind turbines have been efficiently reduced by manufacturers. Therefore, aerodynamic noise has become the main source and it will become even more important as the size of the wind turbines increase, because mechanical noise doesn't increase with the size as fast as aerodynamic noise. It is necessary to assess the relative importance of the different aerodynamic noise sources in order to be able to efficiently reduce their contribution. LEAM has developed a linear microphone array to locate and measure sound sources in horizontal axis wind turbines in-situ. Also, LEAM has satisfactorily applied Active Noise Control in order to reduce the ventilation unit noise.