Improving ducting to increase cooling performance of high-end web servers subjected to significant thermal shadowing – an experimental and computational study

A critical requirement in implementation of air cooling for rack mount servers is management of airflow to ensure that all components, especially critical devices such as CPUs, receive adequate flow as per requirement. In addition, component locations within the chassis play a vital role in passage of airflow and affect the overall system resistance. In this paper, sizeable improvement in chassis ducting is targeted to counteract effects of thermal shadowing in a dual-socket Open Compute web server wherein a CPU is located directly downstream from another. An experimentally-calibrated detailed CFD model of the server is deployed to parameterize design and location of the duct with the objective of understanding the effect of flow bypass on CPU die temperatures and fan power consumption. Enhancements achieved are tested experimentally by constructing a prototype of the improved chassis and reported with 23.4-39.6% savings in fan power consumption, 21.6-26% reduction in fan speeds, and 31.3-37.3% savings in flow rate required by the server. 6.4% to 16.7% reduction in acoustics noise levels caused by server fans is also presented.