Hydraulic Machines may be defined as that Branch of Engineering,which deals with the Machine run by Water under some head,or rising the Water to some higher level.
The Properties of Water at rest and at motion:-
01)Water keeps its surface level,at rest
02)The Water exerts a uniform Pressure in all direction.
03)The Velocity of Water,in a channel,is more at the centre than at the sides.
04)The Velocity of Water is directly proportional to the slope of the channel bed.
05)The Pressure of the Water is equal to its Weight and thus,the Pressure increases with the depth.
The Important Properties of Liquid.
01)Density of Water:-
The mass per unit Volume at a standard Temperature and Pressure is known as Density of Liquid.It is denoted by "rho".
02)Specific Weight of Water:-
The Weight per unit Volume,at standard Temperature and Pressure is known as Specific Weight of Liquid.Denoted by "w"
03)Specific Gravity of Water:-
It is the ratio of its Specific Weight to that of a standard substance at a standard Temperature.
04)Compressibility of Water:-
The variation in its Volume,with the variation in its Pressure is known as Compressibility of Water.The Water is considered to be an incompressible liquid.
05)Surface Tension of Water:-
It is the property of Water,which enables it to resist Tensile Stress.It is due to Cohesion between the Molecules at the surface of a liquid.Drops of rain water sphere because liquid surface has a tendency to reduce its surface as small as possible.
06)Capillarity of Water:-
The Phenomenon of rising Water in the tube of smaller diameter is called the Capillary rise.
07)Viscosity of Water:-
The property of Liquid which controls its rate of flow is known as "Viscosity of Water".
Difference between Mass and Weight.
It is the amount of matter contained in a given body,and does not vary with the change in its position on the Earth's surface.
It is the amount of pull,which the Earth exerts upon a given body,therefore the Weight of the body will vary with its position on the earth's surface.