سال انتشار: ۱۳۸۶
محل انتشار: سومین کنفرانس بین المللی مدیریت جامع بحران در حوادث غیرمترقبه
تعداد صفحات: ۱۲
HARIRI ASLI-KAVEH – B.E OF MECHANICAL ENGINEERING – M.E OF SYSTEM ENGINEERING STUDENT OF PHD IN MECHANICAL ENGINEERING
Water hammer (or, more generally, fluid hammer) is a Disaster pressure surge or wave caused by the kinetic energy of a fluid in motion when it is forced to stop or change direction suddenly. It depends on the fluid compressibility where there are sudden changes in pressure due to interpenetration of two fluids such as water & vapor. Mechanical engineers frequently encounter the flow of a mixture of two fluids in pipes. Liquid-gas or liquid-vapor mixtures are encountered in condensers and evaporators, gas-liquid reactors, and combustion systems. Several factors can contribute to water hammer such as: Improperly sized piping in relation to water flow velocity High water pressure with no pressure-reducing valve Straight runs that are too long without bends; Poor strapping of piping system to structure No dampening system in place to reduce or absorb shockwaves. For example, if a valve is closed suddenly at an end of a pipeline system a water hammer wave propagates in the pipe. Moving water in a pipe has kinetic energy proportional to the mass of the water in a given volume times the square of the velocity of the water. Geometry information systems can eliminate water hammer during abnormal operations. Abnormal operations include things like initial startup and power out conditions in Earthquake. For these abnormal circumstances it is important to have safety equipment installed. Equipment that will help during a power outage includes surge tanks, gas vessels, surge anticipator valves, and pressure relief valves. Variable speed pumps have computerized electronic controls and are only as dependable as other electronic devices such as computers, cell phones, and televisions link to GIS. By application of pipeline geo reference coordination in database under GIS management and data exchange between receiver and transducer from pipeline to programmable logic control “plc, all of the system can be on- line controlled by transmitting pulls to valves and pump station and sure tank and protected from water hammer disaster.