Adaptive quarter wavelength tube tuned by varying air temperature

摘要

An Adaptive Quarter-Wavelength Tube (AQWT) that can be tuned by varying the air temperature was simulated with both a 90° notched and bell-mouth t-piece using Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA). The QWT was tested experimentally to determine the noise reduction that could be achieved at the fundamental firing frequency of an internal combustion engine (ICE). Electrical air heaters injected hot air into the QWT that varied the speed of sound of air and therefore varied the tuned length of the tube. Results showed that the fundamental firing frequency could be attenuated by approximately 5 dB over a 65-75 Hz range by varying the air temperature within the QWT.