Hydrolock

As water hammer, various physical phenomena are referred to, in which a strong mechanical shock is generated by water. The reason is the very low compressibility of the water, which is about a 20000stel of the bulk modulus of air.

Water hammer in piston engines

In the cylinders of reciprocating engines gases with the initial volume VHub Vrest be compressed into a much smaller residual volume Vrest. The compression ratio is within the normal operating often at 10:1. If there is water in the piston chamber, the residual volume available to the gas at the end of the working stroke (top dead center ) are available, and can even be reduced to zero. This increases the compression ratio at the end of the piston stroke significantly higher values ​​and the acting forces are multiplied. That always means a strong overuse of the components of the compression chamber (piston, cylinder head or head ) as well as the driving parts ( piston rod, connecting rod ).

In the railway transport is denoted by water hammer damage to the cylinder by condensation. When stopping the steam locomotive of in-cylinder steam condenses to water. When restarting, under certain circumstances, the condensation on the side of the exhaust stroke not be pushed out and rips in need of its compressibility mostly the cylinder cover of the bolt off. To avoid water hammer are generally short open when starting the cylinder valves to drain condensation.

As water hammer also a ( quite rare ) is called failure in internal combustion engines, when due to a leak in the head gasket cooling water passes into the compression chamber ( which is designed for the compression of gases ) and then stops abruptly in the compression stroke of the piston - with the risk of a bent connecting rod, the flask breakage and ultimately to an engine failure. Water hammer can also occur in water splashes with internal combustion engines in motor vehicles when the fording of the vehicle is exceeded and water passes through the intake into the compression chambers.

Water hammer in water pipes

As water hammer is also called a pressure surge in a fluid- carrying pipe, which is caused by the sudden closing of a valve at the end of the pipe. The inertia of the water flowing in the pipe here leads to an enormous increase in pressure because the bulk modulus is very large. You can see the flowing cylindrical water column model pictured as moving metal cylinder, which is abruptly stopped on a wall.

A beneficial applications of the pressure surge is the hydraulic ram, in which a large amount of water at low heads is stopped abruptly, to pump a small amount of water to a greater height (see conservation of energy ).

Water hammer can develop by the pressure surge in the water lines a harmful effect shows itself as the leakage in the pipe system or connected equipment within a building. The increase in pressure can be mitigated by water hammer arrester. These are small membrane expansion vessels (MAG ), which are installed in the water line train between the valve and pressure pulse trigger the feeding pressure reducer. The closer the water hammer arrester on the valve, the greater the attenuation of the pressure surge. For multiple surge triggers in different water -pipeline setting it between the division into the strands and the feeding pressure reducer. Alternatively, pressure surges can be reduced by reducing the amount of water flowing through and thus the flow rate to a limited extent. This solution is considered as a transitional state solution because the water flow is reduced at all points of use.

Water hammer in steam systems

This condensation shock is a physical phenomenon that can be observed in pressure increases in steam systems. Within a quantity of steam always are condensation nuclei that can arise from water in an increase in pressure without concomitant increase in temperature smallest drops. This process does not run continuously, but at the phase transition rather suddenly and is a great danger, for example dar. for piping and equipment within a steam power plant

Chuff

This sometimes also referred to as water hammer phenomenon occurs when vapor bubbles implode in water.

Drop impact

This is known as drop impact or drops erosion wear effect occurs when droplets at high speed hit a surface.

Cavitation

Cavitation is a microscopic form of steam blows.