Hydraulic transients water hammer

Transient Flows in Hydraulic Circuits Water Hammers... 

Cavitation Loosely regarded as related to water hammer and hydraulic transients because it may cause similar vibration and equipment damage, cavitation is the phenomenon of collapse of vapor bubbles in flowing liquid. These bubbles may be formed anywhere the local liquid pressure drops below the vapor pressure, or they may be injected into the liquid, as when steam is sparged into water. Local low-pressure zones may be produced by local velocity increases (in accordance with the Bernoulli equation see the preceding Conservation Equations subsection) as in eddies or vortices, or near boundary contours by rapid vibration of a boundary by separation of liquid during water hammer or by an overall reduction in static pressure, as due to pressure drop in the suction line of a pump. 

Rich was considered an authority on the design of hydro-electric power plants, and overall hydraulic engineering. Over a career of almost sixty years he was in charge of design of major installations in the eastern USA. He was credited for designing such notable works as the Conowingo Hydropower Project, the Fort Peck Project, the Cape Cod Ship Canal, the Marimbondo Hydroelectric Project in Brazil, or the St. Lawrence Power Project. He was known for a number of textbooks and papers. These include Hydraulic transients, and a chapter in the Handbook of applied hydraulics, edited by Calvin Victor Davis (1877-1946). He was an expert of water hammer phenomena and related hydraulic transients. 

Streeter made a lasting impact on the field of computational fluid transients. With Evan B. Wylie (1931-) he wrote three books on this topic, namely Hydraulic transients in 1967, Fluid transients in 1982, and Fluid transients in systems in 1993. A paper dealing with computer analysis on water hammer was published as early as in 1963, thereby popularizing the computer-based method of characteristics combined with specific time intervals. At that time the predicted variables did not accurately attenuate because of numerical interpolations. In the mid-1960s, the effect of turbo-machinery on water hammer analysis was accounted for, given its relevance for the industry. 

Hydraulic Transients in Pipes. Unsteady flow in pipe networks can be gradual therefore, it can be modeled as a series of steady solutions in an extended period simulation, mostly usefiil for water-quality analysis. However, abrupt changes in a valve position, a sudden shutoff of a pump because of power failure, or a rapid change in demand could cause a hydrauUc transient or a water hammer that travels back and forth in the system at high speed, causing large pressure fluctuations that could cause pipe rupture or collapse. 

This chapter deals only with established regime (steady-state) flows in a hydranhc circuit. In this framewoik, we emphasize the difference between flows in convergent and divergent pipes, discuss the effect of turbulence on pipe flows, and tackle the problem of cavitation. Transient flows in hydraulic circuits will be dealt with in Chapter 6, when discussing water hammer phenomena. 

The EMTP was based on the Schnyder-Bergeron method [54,55] of traveling-wave analysis in a hydraulic system, well known as a water hammer [52, 53, 54, 55, 56-57]. The Schnyder-Bergeron method was introduced to the field of electrical transients by Frey and Althammer [25]. The method was incorporated with a nodal analysis method by representing all of the circuit elements by a lumped resistance and the current source by Dommel [26]. This is the origin of the EMTP [9,11]. 

System Design Dampening Based on hydraulic transient analysis (water hammer) and modeling thereof [4,] polymer melt delivery systems can be modeled and analyzed for flow and pressure transients [5.] The results provide information on how to optimize a melt delivery system for minimum transmission of flow oscillation to the die. 

A computer program for calculating fluid hammer phenomena in sodium and water circuits of the CEFR has been prepared by Qinghua University. Due to the pool hydraulic properties, there is no any fluid hammer phenomenon at some transient conditions (Table 4)... 

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