About deep well jet pumps:
Above the surface is a standard impeller-diffuser type pump. The output of the diffuser is split, and half to three-fourths of the water is sent back down the well through the Pressure Pipe. At the end of the pressure pipe the water is accelerated through a cone-shaped nozzle at the end of the pressure pipe.
Then the water goes through a Venturi in the Suction Pipe. The venturi has two parts: the Venturi Throat, which is the pinched section of the suction tube; and above that is the venturi itself which is the part where the tube widens and connects to the suction pipe. The venturi speeds up the water causing a pressure drop which sucks in more water through the intake at the very base of the unit. The water goes up the Suction Pipe and through the impeller -- most of it for another trip around to the venturi to keep the deep well jet pump working.
