A Study On The Application Of Active Control On The Staggered Structure Insulation Windows With Natural Ventilation

This thesis focuses on the application of active control on natural ventilation and sound insulation window which is constructed by staggering the external and internal openings of a spaced double glazing window. Firstly, a new acoustical model is proposed based on the research of existed natural ventilation and sound insulation window which is constructed by staggering the external and internal openings of a spaced double glazing window. The model can be used to investigate the sound field in the non-normal incidence condition. An FEM model and some experimental tests are both carried out to prove the validity of the model, which is proved effective. The sound field inside the window can be studied with this new model.Secondly, the sound field inside the window is studied under the condition of the incident of plane waves with different incident angles. The situations with different sound absorption materials attached inside the window are also considered with the new model. The sound field is affected by different incident angles and higher frequencies are more easily affected than lower frequencies. Changes of the inner sound field with different sound absorption materials attached inside the window show that the sound field tends to be smoother with the materials of higher absorption coefficient.Last, the feedforward active noise control technology is applied on the natural ventilation window which staggers the external and internal openings of a spaced double glazing window. The active noise control technology brings 10 dB extra noise reduction for the broadband noise from 0 Hz to 1600 Hz. It seems that changing the noise source location has little influence on the noise reduction results with the fixed filter coefficient. The field test also proves that the effect of using active noise control system would be comparable to that of a closed single layer window. The natural ventilation window with the staggered structure and active control technique can achieve higher noise reduction and has great practical value in the future.