Fluid Mechanics (Part-4) (General Engineering) (SSC JE)

Pelton turbine–Pelton turbine or wheel is a tangential flow impulse turbine which is based on kinetic energy and pressure is constant. The pelton wheel extracts energy from the impulse of moving water as opposed to water's dead weight. It is work on high head and low flow rate.

Francis turbine–It is a inward flow reaction turbine, which is based on kinetic and pressure energy. Flow of water through the blades combines both radial and axial flow.

Kaplan turbine–It is a propeller type reaction turbine. It is used for low head high discharge flow of water is axial through the blades.

Streamline is defined as an imaginary line within the flow. Tangent act any point on it indicates the velocity at that point. Streamline flow is more likely for liquids having low density and high viscosity.

Streak line–It is a locus of the temporary locations of all particles that have passed through a fixed point in the flow field at any instant of time.

Note–Streamline, path line and streak line are identical in case of steady flow.

Bernoulli's equation–In an ideal incompressible fluid when the flow is steady and continuous the sum of pressure energy, potential energy and kinetic energy is constant along a streamline.
• It states that an decrease in the velocity of fluid occurs simultaneously with increase in static pressure or fluid potential vice versa.

Orifice is an small opening or hole of any cross-section on the side or at the bottom of a tank through which a fluid is flowing orifice is used to measuring the rate of flow of fluid.
Hydraulic or orifice co-efficients–

The following are the assumption made in the derivation of Bernoulli's equation–
1. The fluid is ideal and viscosity is zero.
2. The fluid is homogeneous and incompressible.
3. The flow is steady.
4. The flow is irrotational.
5. The flow is continuous steady and along the streamline.
6. The flow is one dimensional. Bernoulli's equation–
• The Bernoulli's equation is applied to venturimeter orifice meter and pitot tube.

According to Newton's law of viscosity, shear stress is directly proportional to the rate of deformation or velocity gradient across the flow.

Centrifugal pump–The hydraulic energy in the form of pressure energy. If the mechanical energy is converted into pressure energy by means of centrifugal force acting on the fluid, then hydraulic machine is called centrifugal pump.
Applications of centrifugal pump
• Agricultural and irrigation purpose
• In petroleum installation to pump oil
• Hydraulic control system
• Transfer raw material
• Pumping of water in buildings
• Fire fighting.