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Prepared by :-

KORAT NIRAV (11ME045)

RIPAL MARAVIA (11ME036)

terms used in fluid flows

(1) Path line :- The path traced by a single fluid in motion over a period of time is called its path line. If an individual particle of fluid is coloured, it will define its path line. Thus the path line shows the direction of the velocity of the same particle at successive instant of time.

(2) Streak line or filament line :- It is instantaneous picture of all the fluid particles in the flow which have passed through a given fixed point. Injecting a stream of dye into a liquid, or smoke into a gas, the result will be streak line.

(3) Stream line :- A streamline is an imaginary line drawn through the flow field in such a way that the velocity vector of the fluid at each and every point on the streamline is tangent to the streamline at that instant. Since at any point on a streamline the velocity is tangential to the streamline, so the component of velocity at right angles to the streamline is always zero. Thus there can be no flow occuring across any streamline. Streamlines cannot ever cross each other. If they cross, the fluid particle will have two velocities at the point of intersection and that is physically impossible.

(4) Stream tube :- It may be defined as a tubular space formed by the collection of streamlines passing through the perimeter of a closed curve. Since there is no flow across a streamline, the fluid inside the stream tube cannot escape through its walls, and behaves as if it were contained in an imaginary pipe.

Types of fluid flows(1) Steady flow :- It is defined as that type of flow in which the fluid characteristics like pressure, velocity, density, etc. at a point do not change with respect to time.

(2) Unsteady flow :- It is defined as the flow in which the fluid characteristics like pressure, velocity, density, etc. at a point changes with respect to time.

(3) Uniform flow :- It is defined as that type of flow in which the flow parameters like pressure, velocity, density, etc. at a given time do not change with respect to space.

(4) Non-Uniform flow :- The flow in which the flow parameters like pressure, velocity, density, etc. at a given time change with respect to time.

(5) Laminar flow :- The flow in which the fluid particles move in layers or lamina with one layer sliding over the another is called laminar flow.

(6) Turbulent flow :- The flow in which the fluid particles move in zigzag way is called the turbulent flow.

(7) One dimensional flow :- It is that type of flow in which the flow parameters such as pressure, velocity and elevation are the function of time and one space coordinates only.

(8) Two dimensional flow :- It is a type of flow in which the flow parameters are the function of time and two coordinate of space.

(9) Three dimensional flow :- It is that type of flow in which the flow parameters vary in all the three directions, the stream lines are space curves.

Venturiemeter The Venturiemeter was invented by

Clements Hershel in 1887 and has been named in the honour of an Italian Engineer Venturi.

It is a device used for measuring the rate of flow of a fluid flowing through a pipe.

The working principle of Venturiemeter is based on Bernoulli’s equation.

venturiemeter

The venturiemeter consists of three parts :

(i)A short converging part(ii)Throat(iii)Diverging part

Uses of venturiemeter Venturiemeter is used to measure the speed of fluid.

Air flows through a venturie channel of a carburetor in automobiles

At throat, pressure being low, the fluid is sucked in and proper mixture of air and fuel is made available for combustion.

Venturiemeters used in daily life

Venturiemeters used in daily life

orificemeter Pipe orifice is a device used for measuring the rate for

measuring the rate of flow of a fluid through a pipe.

It is also called orifice meter or orifice plate.

The orifice meter consists of a thin, circular plate with a hole in it.

The plate is held in the pipeline between two flanges.

Pipe orifice is a cheaper device as compared to venturiemeter.

It also works on the same principle as of venturiemeter.

orificemeter

The orifice diameter is kept generally 0.5 times the diameter of the pipe, though it may vary from 0.4 to 0.8 times the pipe diameter.

The orificemeter is as shown in the fig.

Orifice meters used in daily life

Modern orifice meters discovered

If the available head of liquid is less than five times the diameter or vertical dimension of orifice, the orifice is called large orifice.

If the head of liquid from the center of orifice is more than five times the diameter or vertical dimension of orifice, the orifice is called small orifice.

In case of small orifice, the velocity in the entire cross section of the jet is considered to be constant and discharge can be calculated by Q=Cd x a x .

Nowadays, orifice meters are used instead of venturiemeter. Thus orifice meters have replaced venturiemeters.

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