First, what kind of impeller and pump is this? I mostly see centrifugal impellers in the net.
I googled about this but didn't find direct reference to it. Most are about centrifugal pumps. Although I managed to find a video that discussed something similar to it. But in the following, the vane is flexible and the upper wall seals it and the presenter says it creates negative pressure right at the part pointed by the screwdriver. However, in the impeller above, the vanes are solid and not flexible, so where is the negative pressure created that suck the water and how is the cavitation performance of the above?