Error Sensor Placement for Active Control of an Axial Cooling Fan Error Sensor Placement for Active Control of an Axial Cooling Fan
A weakness of the current near-field modeling process is that a point monopole source is used to characterize the acoustic noise from an axial cooling fan, which may have multipole characteristics. A more complete characterization of fan noise may be obtained using a procedure based on the work of Martin and Roure [J. Sound Vib. 201 (5), 577–593 (1997)]. Pressure values are obtained over a hemisphere in the far field of a primary source and the contributions from point source distributions up to the second order, centered at the primary source, may be calculated using a multipole expansion. The source information is then used in the aforementioned theoretical near-field calculation of pressure. The error sensors are positioned using the complete fan characterization. The global far-field attenuation for the multipole expansion model of fan noise is compared to that of previous experiments. Results show that the multipole expansion model yields a more accurate representation the near field, but is not successful in achieving greater sound power reductions in the far field.
School:Brigham Young University
School Location:USA - Utah
Source Type:Master's Thesis
Keywords:fan cooling fans axial noise control active anc modeling model error sensor placement near field pressure sensors mapping multipole expansion spherical harmonics multipoles
Date of Publication:09/18/2007