What are the possible types of flow in open
channel with respect to space and time?
A. steady
and unsteady flow
B. uniform and non uniform flow
What is Compressibility?
It is the property
by virtue of which fluids undergoes a change in volume under the action of
external pressure.
What is Newton’s law of Viscosity?
According to
Newton’s law of viscosity the shear force F acting between two layers of fluid
is proportional to the difference in their velocities du and area A of the
plate and inversely proportional to the distance between them.
What is cohesion and adhesion in fluids?
Cohesion is due to
the force of attraction between the molecules of the same liquid.
Adhesion is due to
the force of attraction between the molecules of two different liquids or
between the molecules of the liquid and molecules of the solid boundary
surface.
State momentum of
momentum equation?
It states that the
resulting torque acting on a rotating fluid is equal to the rate of change of
moment of momentum.
What is momentum
equation?
It is based on the
law of conservation of momentum or on the momentum principle It states that, the net force acting on a fluid
mass is equal to the change in momentum of flow per unit time in that
direction.
What is known by
governing of a turbine?
Governing of a
turbine is defined as the operation by which the speed of the turbine is kept
constant under all conditions of working. It is done by oil pressure generator.
Explain gross head.
The difference
between head race level and tail race level when no water is flowing is known
as gross head.
Explain net head.
It is defined as the
head available at the inlet of turbine .If Hf is the loss due to friction
between water and penstock then net head
H=Hg-Hf
What is breaking
jet?
When the nozzle is
completely closed ,the amount of water striking the runner reduces to zero but
the runner due to inertia goes on revolving for a long time to stop the runner
in a short time a small nozzle is provided which direct the jet of water on the
back of vanes .This jet of water is called breaking jet.
What is jet ratio?
It is the ratio of
pitch diameter (D) to the diameter of jet (d).
What is Draft tube?
A tube or pipe of
gradually increasing area is used for discharging water from the exit of the turbine to the tail race
is called draft tube.
What is Degree of
Reaction (R)?
It is defined as the
ratio of change of pressure energy inside the runner to the change of total
energy outside the runner.
What is radial
discharge?
This means the angle
made by absolute velocity with the tangent on the wheel is 90 and the component
of whirl velocity is zero.
What is Francis
turbine?
Inward flow reaction
turbine having radial discharge at outlet is known as Francis turbine
What is propeller
turbine?
This is an example
of axial flow reaction turbine. Here the vanes are fixed to the hub and are not
adjustable.
What is Kaplan
turbine?
This is an example
of axial flow reaction turbine. Here the vanes are not fixed to the hub and are
adjustable.
What are the uses of
draft tube?
1.
The net head on the turbine increases.
2. Due to increase in net head the power and efficiency of the turbine
also increases.
3. The large amount of rejected
kinetic energy is converted in to useful pressure energy
What are types of
draft tube?
1. Conical draft tube
2. Simple elbow tube
3. Moody spreading tube
4. Draft tube with circular inlet
and rectangular outlet.
What is Hydraulic
Efficiency?
It is defined as the
ratio of power delivered to the runner to the power supplied at the inlet.
What is mechanical
efficiency?
It is defined as the
ratio of power at the shaft of the turbine to the power delivered by the water
to runner.
What is volumetric
efficiency?
It is defined as the
ratio of volume of water actually striking the runner to the Volume of water
supplied to the runner.
What is overall
efficiency?
It is defined as the
ratio of shaft power by water power.