That's a water impeller that goes inside a water pump.

它是个排水叶轮，放在水泵里的。

Three large impeller fans quietly channel air from front to back, while a blower pulls heat from the memory.

三个大型叶轮扇空气从前部引到后部，而一个则带走内存的散热。

The pump is a brushless DC motor, constructed from a PCB, a control chip, and a stator on the dry side, a barrier in the middle, and then the permanent magnet rotor and impeller on the liquid side.

泵是一款无刷直流电，由干侧的电路板、控制芯片和定子，中间的隔板， 以及液侧的永磁转子和叶轮组成。