Patent attributes
A method of operating variable pitch fans in series to cool an operating computer system. The method comprises running a first variable pitch fan with blades positioned at an operational pitch to induce airflow through the computer system and through a second variable pitch fan disposed in series with the first fan, and, simultaneously, not running the second variable pitch fan with blades positioned for minimal impedance to the airflow. In response to detecting a failure condition of the first fan, the method includes running the second fan with blades positioned at an operational pitch to induce airflow through the computer system and through the first fan, and, simultaneously, not running the first fan with blades positioned for minimal impedance to the airflow. Preferably, the method includes locking the rotor of a fan that is not running, and locking the blades of the non-running fan in a minimal impedance position.
