Water hammer pressure

Pipeline parameter Pn aV0 2gH maximum water-hammer pressure rise 2 x static pressure Water hammer... 

Another study carried out by these authors [93] modeled the collapsing motion of a single bubble near an electrode surface, and equations for the motion of a spherical gas bubble were obtained. The jet speed and water hammer pressure during jet flow (liquid jet) were calculated, and when the jet speed was 120 m/s, the water hammer pressure was approximately 200 MPa upon the electrode surface. This pressure played an important part in the fineness of the crystal deposits. Mass transfer during the electrode reaction was by turbulent diffusion. The diffusion layer thickness was reduced to approximately 1/10th its size in the presence of the ultrasonic field. The baths contained the ions Cl-, SO -, and Zn2+. The ultrasonic frequency employed in the experiments was 40 kHz and it was seen that ultrasound considerably increased the deposition rate and current efficiency, as well as the smoothness and hardness of the deposit. Microscopy studies showed that the... 

Recently Perusich and Alkire [105] have proposed a mathematical model to determine the reaction and transport between liquid microjets and a reactive solid surface. Conditions were established under which oxide depassivation and repassivation occurs as a function of ultrasonic intensity, surface film thickness, and fluid microjet surface coverage. The model was based on the concept that cavitation induces sufficient momentum and mass transfer rates (water hammer pressures as described earlier) at a surface to create oxide film stresses leading to depassivation. The model was used to evaluate experimental data on the corrosion behavior of iron in sulfuric acid [106,107], Focused ultrasound was used to investigate processes that influence depassivation and repassivation phenomena on pure and cast iron in 2N H2S04 at two ultrasound frequencies and at power intensities of up to 7.8 kW/cm2. 

The underlying premise of the cloud collapse theory is that the first bubbles to collapse are those at the periphery of a cavitation cloud, and they in turn transfer collapse energy to the core of the bubble cluster, thus intensifying water hammer pressures. 

Dawson, F.M., Kalinske, AA. (1939). Methods of calculating water-hammer pressures. Journal of the American Water Works Association 31(11) 1835-1864. 

Water Hammer/Pressure Surge. The effects and calcnlations for water hammer or pressure surge were covered in detail in chapter 3. The following section contains some key design considerations for handling the effects within thermoplastic piping systems. 

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