Axial fans are widely used for various cooling device due to their ability to produce high flow rate to keep system cool. At the same time, the noise generated by these fans causes one of the most serious problems. There are many studies and experiments for fan performance and noise have been perfomed. But there is little research to design fan system considering both performance and noise because of difficulty in obtaining unsteady information about the flow field around the fan system. The objective of this study is to develop an axial fan system design program composed of two design stages considering performance and noise. The program is composed of concept design and preliminary design. Basic fan geometry is generated depending on the performance requirements. Performance curve, velocity distribution and OSPL(overall sound pressure level) are obtained in concept design module. In the preliminary design, a time marching free wake analysis is employed in the flow calculations and the acoustic analogy is used for the discrete fan noise. The effect of fan case is included in the flow calculation. An acoustic pressure is obtained with the unsteady aerodynamic information calculated in the free wake analysis.
In this study, aerodynamic and acoustic calculations are carried out on the automotive cooling fan and system using the design program. Effects of various design parameters are studied through the free wake analysis and experiments. It carried out that sweep angle and chord length, distance between the case and fan, shape of the case are important parameters. Better performance and noise characteristic are obtained for the new design fan using the methodology. Furthermore through the modification of the fan system geometry parameters, the fan system produce more flow rate and become less noisy.
