An ESP pump includes a first centrifugal pump having a first vane design to operate in a clockwise direction, and a second centrifugal pump having a second vane design to operate in a counterclockwise direction, with a submersible induction or permanent magnet motor for driving the first and second centrifugal pumps. The first and second centrifugal pumps being connected to a common shaft.

A pump is provided that reverses polarity of the current to reverse the rotation of an impeller on failure to clear objects that may be blocking the impeller. The pump may have an impeller configured to move fluid through the pump in a common direction regardless of which way the impeller rotates, an electric motor configured to drive the impeller, and a controller configured to detect potential failure of the impeller to rotate, and, in response to detection of the potential failure, reverse polarity of current to the electric motor to reverse rotation of the impeller.

A blood pump with a rotor can be driven to rotate about an axis of rotation for conveying blood. A control is being configured to operate the rotor successively in time, or alternately several times, in a first conveying mode and at least in one second conveying mode. In order to avoid dead water areas in the region of the rotor and possible thrombus formation the direction of rotation of the rotor is reversed in the second conveying mode compared to operation in the first conveying mode.

Various devices, systems, and methods are described herein that provide bi-directional, and even multi-directional airflow within fan systems. These fan systems can be utilized by devices such as datacenter switches to change from one direction of airflow (such as port side inlet) to another direction (such as port side exhaust). This can be done manually by having a multi-directional fan housed within an enclosure that provides access through a hatch door. The multi-directional fan can be removed and reoriented to a second direction, thus providing airflow with the same quality and pressure in multiple directions. Fan changes can also be automated through one or more interlocking rotational gears coupled to the fans within a housing, such that rotating one gear will rotate each of the fans within the housing, thus changing the direction of the airflow. By doing this, only one fan is needed to provide airflow in multiple directions.