Computational Fluid Dynamics - A Tool for Optimized Fan and Blower Design

The power density in electronic equipment and thus the overall power consumption are increasing continuously. This is especially true for the new technologies in telecommunication systems like the UMTS base stations, where full control over thermal management at any point inside the enclosures is mandatory. Since an improved cooling normally is based on higher air flow rates, acoustic noise becomes more and more relevant, because the installed systems are not accepted if they do not fulfil low noise specifications. For a given forced convection cooled equipment - typically using fans or blowers - a CFD based numerical analysis provides design information which allows sophisticated flow control inside the enclosure. The next step is to use CFD based optimisation of the fans and blowers themselves in order to optimise these building blocks for maximum performance at low noise. This paper shows how the performance of equipment fans and blowers can be optimised by using Computer Simulation during the design phase. Besides the correlation between flow rate and pressure the simulation results provide additional information about the sources for aerodynamic acoustic noise generated by the rotating blades. The target is to integrate fan and blower optimisation into a customised thermal management on system level. Thus concurrent use of modem CFD tools enables sophisticated cooling solutions with control over flow, temperatures and noise simultaneously.