Oral questions collection v1

Page 1

Waterjet (WJ -AWJ) • Inverted osmosis In order to understand what inverted osmosis is, we need first to study what osmosis is. Osmosis is a process according to which water moves from the solution with lowest concentration to the one with higher concentration through a semi permeable membrane. This process implies having a difference of pressure known as osmosis pressure. With inverted osmosis we mean the process in which we apply an external pressure higher to the osmotic pressure to the more concentrated solution to make it pass through the se mipermeable membrane and have obtain a less concentrated solution. This process is performed in most of the waterjet technologies in order to improve even more the quality of the water to be used inside the system. usually this is the third step that it is done in order to purify the water which is taken from the water network. The other two main steps are: 1. Deionization and softening = in this case the water passes through a cationic resin that reduces the concentration of ions of calcium and magnesium. Con temporary other types of resins are used in order to reduce the presence of chlorides and sulphates to reach a natural pH. 2. Filtering =the water passes through an activated charcoal filter to reduce the suspended particles as the residual chlorine • P-curves of waterjet and power of the waterjet. The hydraulic power of the water can be computed with the following equation: 𝑃ℎ𝑦𝑑𝑟=1 2𝑚̇𝑤𝑣𝑗 2 • Provide the formula related to water compressibility and the plot in which we compare the different speed (compressible and non-compressible) with respect to the pressure - Demonstration how to obtain jet velocity expression The theoretical speed of the water jet leaving the primary nozzle 𝑣𝑡ℎ,𝑐, considering water as a compressible…