Water hammer analysis should be performed for normal, emergency and catastrophic operating conditions. Hydraulic transient theory in pressurized networks, a steadystate condition or transient event at one point in the system can affect all other parts of the system. Modelling and transient simulation of water flow in pipelines. Pdf on may 24, 1994, arris s tijsseling and others published the influence of support. It is easier to analyze a system by rigid column theory than by elastic theory. Static and steady hgl versus rigid and elastic transient head envelopes. Water hammer analysis there are computer programs available for analyzing pipeline systems with and without water hammer. Water hammer dissipation in pneumatic slug tests ostendorf. Simple guide for design of air vessels for water hammer. Water hammer effect is normally happening in daily life and only that people not realize it. However, if the water column is internally disturbed, a rigid column model can no longer capture the resulting water hammer pressures and a more complete dynamic model is then required to simulate the key. To fully study structural vibration in these types of applications, engineers must model the coupling mechanisms for fluid structure interaction fsi.
Water hammer is usually recognized by a banging or thumping in water lines. Understanding water hammer ohio awwa state conference presentation september 17, 2004 dan barr, pe 2. Water hammer is part of the larger subject of transient flow or surge analysis. The complexity and intricate physics of water hammer translated into significant. Water hammer definition, causes, factors affecting water. The resultant release of water generated a lowpressure wave resulting in substantial column separation that caused crushing pipe collapse of a significant portion of the upstream pipeline due to the external atmospheric pressure. Derive and use the unsteady incompressible pipeflow. In the case where the fluid is incompressible, then water hammer can be analyzed by different approaches, which is known as the rigid column theory, which ignores compressibility of the fluid and. The water hammer theory and rigid column match, and may be superimposed so long as the former frequency is much faster than that of the latter and the water hammer dissipation is rapid. The italian engineer lorenzo allievi was the first one who successfully investigate the water hammer phenomenon, which water hammer can be analyzed by two different approaches, rigid column theory. The pressure head due caused by the water hammer is p cv0 but for rigid pipe. Rigid water hammer theory and the numerical model for hydraulic transients based on moc are employed to illustrate how the geometric characteristics affect the extreme water hammer pressure, such as the maximum scp. In the analysis they applied both classic waterhammer theory and a. Engineering design guideline fluid flow hydraulic surge rev01all.
For these detailed studies, software from ansys has an outstanding breadth. Wave speed for water, without presence of free air or gas, the more general equation to calculate the water hammer wave speed magnitude in onedimensional flows is watters, 1984. This is to certify that the work in this thesis entitled analysis for water hammer considering the effect of fluid structure interaction in straight pipes by suyash mishra 108me050, has been carried out under my supervision in partial fulfillment of the requirements for the. Predict pressure rise and the speed of waterhammer waves in rigid and non rigid pipes. Water hammer can generate very high pressure transients which could burst a pipe and can generate pipeline vibrations. When the time it takes a valve to close is long compared to the. Closure to discussion of rigid water column theory in water hammer problems 1964, asme j. Investigation of water hammer effect through pipeline system. Equations and charts for solving pressurerise problems by the rigid watercolumn theory are presented with an example of their application.
The basic mechanisms causing water hammer events in pipe systems are introduced. Jul 18, 2015 water hammer is the special case when the flow is stop very rapidly or instantaneously. This paper considers water hammer analysis of pumping systems for control of water in underground mines. Rapid filling analysis of pipelines with undulating. In his work, he analyzed complex geometries and underlined the importance of. Analyzing vibration with acoustic structural coupling. The rigid column theory is a significant factor in the design, construction and operation of pipelines. Jan 03, 2017 when a there is a sudden or instantaneous change of flow in a pipe this causes water hammer. Based on water hammer theory, a numerical model is proposed for simulating rapid filling in the pipe system with undulating profile.
The water hammer coupled model called fsi fourequation model describes the axial dynamic behavior of liquidfilled pipes against a water hammer. Paper open access hydraulic transient simulation and. The elastic liquid column model is used for the systems with relatively long tunnels and penstocks, and systems with rapid transients. Assuming the pipe remains full during the filling and neglecting the air and water interactions, the model is formulated through using the method of the characteristics along with an adaptable computational grid. The result is that the pipes move due to the pressure waves in the water, and thus might strike. Analysis for water hammer considering the effect of fluid. Hydropower plants with kaplan turbines are usually comprised of relatively short inlet and outlet conduits. Severe water hammer is damaging for pipes, pumps and alvves and the issue needs to be closely examined. The first to successfully investigate the water hammer problem was the italian engineer lorenzo allievi which water hammer can be analysed by two different approaches, rigid column theory which ignores compressibility of the fluid and elasticity of the walls of the pipe, of by full analysis including elasticity.
Waterhammer is the term applied to pressure surges set up in this way. Fluid mechanics are consultant hydraulic engineers who can analyse and design for surge and water hammer in. Unsteady flow in pipes autumn 20 objectives 1 recognise the potential for large pressure transients when pipe flow is stopped abruptly. Reports utah water research laboratory january 1971 the behavior of pvc pipe under the action of water hammer pressure waves gary z. When discussing the pressure of a fluid, a distinction has to be made between pressure above atmospheric p bar, absolute pressure p bar a and pressure head h m. Water hammer calculator solving for pressure increase given flow velocity, upstream pipe length, valve closing time and inlet pressure water hammer pressure. Pdf the influence of support rigidity on waterhammer pressures. Water hammer can be particularly dangerous because the increase in pressure can be severe enough to rupture a pipe or cause damage to equipment. Chapter 8 unsteady flow analysis by rigid column method. So, water hammer in the home is rarely more than an irritation. Water hammer, laminar flow, turbulent flow, numerical simulation. Consequently, computer models must consider every pipe that is directly connected to a pressurized system, regardless of administrative or political boundaries. Transient pressures caused by a change of flow rate in conduits are often the cause of bursts. The analysis of sudden valve closure and water hammer can either be done assuming that water is completely incompressible and the pipe totally rigid or by assuming that there will be some compression of the water and some expansion of the pipe.
Owing to the potential damage including that caused by the water hammer effect, it is particularly important to arrangements that use pipelines transporting hazardous or flammable fluids. Allievi 9,10 developed a general theory of water hammer from first principles and. Water hammer causes piping, valves, pipe fixtures, sup. Rigid watercolumn theory in waterhammer problems a commentary has been published. One of the first to successfully investigate the water hammer problem was the italian engineer lorenzo allievi water hammer can be analyzed by two different approachesrigid column theory, which ignores compressibility of the fluid and elasticity of the walls of the pipe, or by a full analysis that includes elasticity. The first chapter describes rigid and eroding projectile penetration including the transition between these two cases.
The magnitude of the pulse water hammer can be analyzed by two di. The latter term suitably reflects the harmful effects that the hammer like blows accompanying the pressure surges can have on pipes and system components. Numeric modelling of water hammer effects in penstocks january 20 abstract water hammer represents a complex hydraulic phenomenon with significant consequences on the proper functioning and safety of operation for pipe and conduit systems. Modelling of dynamic pressure conditions in district. The change in slope is directly proportional to the flow change. Numerical coupled modeling of water hammer in quasirigid thin pipes. Water hammer in hydropower plants can be calculated using either elastic or rigid water hammer theory 23.
R rigid water column theory for uniform gate closure, j. It is the special case when there is a sudden change in flow velocity. Bentley hammer makes this easy by tracking the mass inflow or outflow of air or water at any location and by plotting or animating the resulting total energy at any point and time in the system. Thus for water in a rigid pipe, where the wave celeric is for example 1500 ms, for an. Predict pressure rise and the speed of waterhammer waves in rigid and nonrigid pipes. For hydropower plants with long penstocks the elastic water hammer should be used. Manual collection of surge tank volume and timing data. Experimental and numerical analysis of water hammer during the filling process of pipelines cristiano bombardieri, tobias traudt, chiara man. Modelling and transient simulation of water flow in. The flow is considered to be compressible and the effect of pipe elasticity is taken into account by introducing the bulk modulus of. A dynamic simulation of the water hammer e ects arising from such cases gives aluablev information which can be used.
The first to successfully investigate the water hammer problem was the italian engineer lorenzo allievi which water hammer can be analysed by two different approaches, rigid column theory which ignores compressibility of the fluid and elasticity of the walls of the pipe, of by full analysis including elasticity 3. Water hammer analysis of pumping systems for control of water. In this paper, the water hammer phenomenon in a pipeline is simulated using the full reynoldsaveraged navierstokes equations. The water hammer community is ignorant of the work of kries. The influence of pipeline supports stiffness onto the. This is fortunately the case for permeable aquifers, which are most likely to be tested pneumatically. A practical overview of unsteady pipe flow modeling hydratek. The influence of pipeline supports stiffness onto the water hammer run. Air expands with explosive force, whereas water pressure drops as soon as there is a leak.
The latter term suitably reflects the harmful effects that the hammerlike blows accompanying the pressure surges can have on pipes and system components. Optimal boundary control for water hammer suppression in. Expressions for the wave speed in both an infinite fluid and in a thinwalled pipeline is presented. Studies on water hammer forming on sheet metal works. Therefore incompressible flow or surge theory is sometimes sufficient for the analysis. Sep 08, 2016 water hammer causes and effects if the pipe is suddenly closed or opened at the outlet downstream, the mass of water before the closure is still moving forward with some velocity, building up a high pressure and shock waves and hammering noise. With rigid pipework, vibration theory shows that the maximum force can reach twice the value calculated in equation 3. Part of the civil and environmental engineering commons, and the water resource management commons recommended citation. Usually this occurs when a valve such as a tap or faucet closes quickly.
These are compared with the elastic water column theory and the merits of both are discussed. Predict the time series of events at any point in a pipeline following sudden closure. Although it might seem to be a smooth flow, the water inside the pipe actually churns and tumbles as it moves through. Water hammer was so called because it is usually observed as banging sounds in pipes. The technique has been validated against actual measurements of water hammer pressures and provides acceptable. The resultant release of water generated a lowpressure wave resulting in substantial column separation that caused crushing pipe collapse of a significant portion of the upstream pipeline. Domestically,itcanbecausedsometimesby quickly closing a tap, especially if it is a tap that only requires a 908 turn to close it. This chapter presents unsteady flow analysis by rigid column method. Equations and charts for solving pressurerise problems by the rigid water column theory are presented with an example of their application. However to get the worst type of water hammer, a domestic tap would need to be closed very quickly, as pipe lengths are usually small in houses.
The influence of pipeline supports stiffness onto the water hammer run adam adamkowski 1, slawomir henclik 1, waldemar janicki1, mariusz lewandowski 1 isromac 2016 international symposium on transport phenomena and dynamics of rotating machinery hawaii, honolulu april 1015, 2016 abstract water hammer wh phenomenon may produce various. Closure to discussion of rigid watercolumn theory in waterhammer problems 1964, asme j. On the other hand, there are many situations where it is inaccurate or even dangerous to apply this simplified theory and water hammer theory must be applied. In this regard, waterhammer control strategies typically include i changes within the distribution system e. These are compared with the elastic watercolumn theory and the merits of both are discussed. In both cases, the analysis requires the application of newtons second law which leads to the euler equation. Water hammer can cause pipelines to break if the pressure is high enough. The normal sound of water moving through pipes is a steady, even sound. Rapid filling analysis of pipelines with undulating profiles. The rigid water column theory would indicate an infinitely large head rise if a valve in a pipeline carrying liquid were slammed shut instantaneously. Rigid water column theory in water hammer problems a commentary has been published. Water hammer or hydraulic shock is the momentary increase in pressure inside a pipe caused by a sudden change of direction or velocity of the liquid in the pipe. For rigid or quasirigid structure pipeline, supports these behaviors are well described by the classic. The rigid water hammer theory can be used for this case.
Water hammer commonly occurs when a valve is closed suddenly at an end of a pipeline system, and a pressure wave propagates in the pipe. Rigid watercolumn theory in waterhammer problems journal. The rigid column theory and water hammer theory are the two approaches adopted in pressure transient analysis 1,2,9. Industrially however, water hammer can be much more than a minor irritation. By omitting the bending rigidity of the pipe wall and the inertial effects of the pipe in. The magnitude of the pulse water hammer can be analyzed by. Water hammer also interested physiologists who were studying the circulatory system. Water conveyance system on extreme water hammer during. Introduction the rigid column theory is a significant factor in the design, construction and operation of pipelines. Generally, the maximum transient head envelope calculated by rigid water column theory rwct is a straight line, as shown in the following figure. Webster says a concussion or sound of concussion of moving water against the sides of a containing pipe or vessel.