Multiple High Performance Dual Redundant or DR FanTM Modules Optimized For 1U Server Processor Upgrade Program

This paper provides an update on the development, optimization, and commercialization of the series fan technology first introduced at iMAPS Boston, in November, 2003 (reference "high performance dual redundant (DR) fan modules - installing a diffuser element to optimize the series fan configuration", p. 517), and subsequently highlighted by microelectronics reliability (reference "Investigation of increased performance of close stacked tube axial fans due to the inclusion of a diffuser element", accepted for publication). The performance of closely coupled series axial fans is investigated in this paper. Performance may be increased even further beyond the theoretical two fan limit by optimizing the geometry of the channel between the two fans and introducing a flow control element, thereby minimizing the required distance between the two fans. In particular, the use of a primary fan with an output stator is investigated, allowing the overall length of a 40 mm dual redundant (DR) fan module to be reduced to an industry standard 56 mm when used with asymmetrical fans. Multiple such modules may be installed in parallel to further increase performance and reliability. Results are reported for a six module installation in a commercially available 1U server. The goal being to facilitate a processor upgrade program for the server manufacturer, without requiring any further cabinet upgrades. Further, the solution produces less acoustic noise and requires less power than the existing fan setup