G L M Van Der Schrieck

Chapter 1.8 & 5.1.11 G L M Van Der Schrieck

This Book is derived from Chapters 1.8 and 5.1.11 of my main book: "Dredging Technology Book 1: The Basics". It contains 3 hydraulic topics: 1 Water jet theory2 Nozzle design 3 Ejector pump theoryAbove the water level a water jet looks very impressive, but as soon as the water jet is submerged under water the energy of the water jet dissipates very quickly in the surrounding water. Already at a short distance of only 12 times the nozzle diameter the water jet velocity is reduced to 50% and the resulting water jet pressure is reduced to only 25%!It is very important to have a smooth pipeline and nozzle design with friction losses as low as possible . Part 1 of the book deals with these aspects. The major advantage of the Ejector pump is the absence of fast moving parts. And when applying also a suction mouth just a fraction smaller than the inner pipeline diameter than there will be hardly any clogging in the pipeline. However the effective use of an Ejector Pump is less simple than the use of a normal piston pump or a centrifugal pump. The book shows and explains the Ejector Pump Characteristic which is totally different from a centrifugal pump characteristic. Also the limited maximum efficiency of 29% is much lower than the usual 80% efficiency for centrifugal pumps.