Description
• visualisation of water hammer
• operation of a surge chamber
• determining the sound velocity in water
• GUNT software for displaying the water hammer and oscillations
In structures such as hydroelectric power plants, or in systems for supplying water, changes in flow rate result in pressure fluctuations. For example during startup and shutdown of hydraulic machines or by opening and closing shutoff elements. There is a distinction to be made between rapid pressure changes that propagate with the sound velocity(water hammer) and slow pressure changes caused by mass oscillations. Pipeline systems use air vessels or surge chambers to dampen water hammer and mass oscillations.
MR-HM 156 is used to generate and visualise water hammer in pipes and to demonstrate how a surge chamber works. The trainer contains a pipe section with a ball valve and a surge chamber and a second pipe section with a solenoid valve. In the first experiment a water hammer is produced by rapidly closing the ball valve. The sudden deceleration of the water mass releases kinetic energy,which is converted into potential energy in the surge chamber. The resulting pressure oscillations are measured by a pressure sensor behind the surge chamber and displayed in the software as a pressure curve. The oscillation can also be seen as pendulum movement of the water level in the surge chamber. In the second experiment a rapid closing of the solenoid valve in the second pipe section produces a strong water hammer. The water's kinetic energy is converted into pressure energy. The water hammer and the subsequent oscillations are detected by two pressure sensors in the pipe section and displayed in the software as a pressure curve. The water is supplied and the flow rate measured by the supply unit.
Learning objectives/experiments
• demonstrating water hammer in pipes
• determining the sound velocity in water
• understanding how a surge chamber works
• natural frequency in the surge chamber
Specification
[1] functioning of a surge chamber
[2] pipe section with ball valve and surge chamber
[3] surge chamber designed as transparent PMMA tank
[4] pressure sensor behind the water chamber for measuring the pressure wave
[5] pipe section with solenoid valve and two pressure sensors for measuring water hammer
[6] volumetric flow measurement via supply unit
[7] representation of the pressure curves with GUNT software
[8] GUNT software for data acquisition via USB under Windows 7, 8.1, 10
Technical data
Pipe section for pressure oscillations
• copper
• length: 5875mm, inner diameter: 26mm
• ball valve
• surge chamber, PMMA
Height: 825mm, inner diameter: 50mm
Pipe section for water hammer
• copper
• length: 5875mm, inner diameter: 26mm
• distance between sensors: 3000mm
• solenoid valve, closing time: 20…30ms
Tank: 50L
Supply unit
Pump
• power consumption: 550W
• max. flow rate: 230L/min
• max. head: 11m
Tank: 1x 180L, 1x 40L
Measuring ranges
• pressure (pipe section): 2x 0…16bar abs.
• pressure (surge chamber): 0…0,3bar
230V, 50Hz, 1 phase
230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
UL/CSA optional
LxWxH: 6800x800x2050mm (total)
Weight: approx.155kg
Required for operation
PC with Windows
Scope of delivery
1 trainer with supply unit
1 GUNT software CD + USB cable
1 set of instructional material