Water hammer in pipes is a significant problem in engineering as they can cause severe damage to piping, fittings and system components. Water hammer is caused by the inertia effect of the flowing fluid being subjected to an abrupt changes in velocity, when rapidly closing a valve. Therefore, knowledge about the emergence of water hammer is an important aspect of designing pipework systems.
The trainer can be used to study water hammer and pressure waves in long pipelines. Water hammer is generated by closing a valve at the end of the pipe section. The water hammer is then reflected to the beginning of the pipe as an inverted wave. A pressure vessel with air cushion at the start of the pipe section simulates the open beginning of the pipe, so that there is a clear reflection of the wave. In order to achieve reflection times that are large enough, a 60m long pipe section has been installed, which is shaped as a coiled tube to save space.
In experiments, the emergence of water hammer is studied as a function of the valve closing times. The trainer therefore includes two solenoid valves, one with constant closing time and one with adjustable closing time. The resulting pressure oscillations are measured by a pressure sensor and the pressure curve is displayed software.
A valve is used to adjust the flow rate. System pressure and flow rate are displayed. A safety valve protects the system against overpressure.
The well-structured instructional material sets out the fundamentals and provides a step-by-step guide through the experiments.
Learning Objectives / Experiments
Water hammer as a function of flow rate
Water hammer as a function of valve closing time
Display pressure curve
Determine reflection time
Calculation of the velocity of sound in water
Specification
Investigation of water hammer and pressure waves in pipes
Pipe section as coiled tube to save space
Generation of water hammer via solenoid valve with constant closing time
Generation of water hammer via solenoid valve with adjustable closing time
Pressure vessel with air cushion reflects the wave
Safety valve protects against overpressure in the system