Propeller pumps, with their capacity for pumping large volumes of water, have long been used for drainage works and stormwater and floodwater control. “Now, with this new technology, we’ve opened up ...

The pump's components include a tiny, rapidly spinning, collapsible impeller that is housed within a collapsible cannula, or tube.

MHDs, which use electromagnetism instead of physical propellers, promise near-silent propulsion, a boon to submarines —and the ships that hunt them. DARPA PUMPs It Getty Images ...