### Applied Hydraulic Engineering–2 Marks with Answers ( Part 1 )

Anna University

Department of Civil Engineering

Subject Name: Applied Hydraulic Engineering

Subject Code: CE2253

Year / Sem : 2rd Yr / 4th Sem

Two Marks with Answers (Part 1 out of 3)

1.What do you mean by turbine?

The hydraulic machine which convert the hydraulic energy in to mechanical energy is called turbine

2.Define pump :

It is defined as the hydraulic machine which convert mechanical energy in to hydraulic energy

3.Define sub critical flow:

If the froude number is less than one then the flow is said to be sub critical flow

4.Define critical flow:

If the froude number is less equal to one it is called as critical flow.

5.Define supercritical flow:

If the froude number is greater than one it is called as super critical flow

6. What are the possible types of flow in open channel with respect to space and time?

B,uniform and nonuniform flow

7.what do you know about uniform and non uniform flow?

Uniform flow: If the given length of the channel ,depth ,velocity ,the rate of flow, cross section are constant.

Non Uniform flow: If the given length of the channel ,depth ,velocity ,the rate of flow, cross section are not constant.

8.Define specific energy:

It is defined as energy per unit weight of the liquid with respect to the bottom of the channel.

9.What is meant by wetted perimeter?

The wetted perimeter (p) is the length of the line of intersection of the channel wetted surface with the cross section plan normal to the direction of flow.

10.Define critical depth:

It is defined as the depth of flow of water at which the specific energy is minimum.

11.Define critical velocity:

The velocity of flow at the critical depth is known as critical velocity

12.Define the term most economical section of the channel:

A section of the channel is said to be most economical when the cost of construction of the channel is minimum. But the cost of construction depend up on the excavation and lining to keep the cost minimum The wetted perimeter for a given discharge should be minimum.

If the change in depth in a varying flow is gradual so that the curvature of the streaming line is not excessive such flow is called gradually varying flow.

14.Define Rapidly varying flow

If the curvature in a varied flow is large and depth changes appreciably over short

length it is called rapidly varying flow.

15.Define affux

The maximum increase in water level due to obstruction in the path of flow is known as affux.

16.Define length of backwater curve

The distance along the bed of the channel between the section where water starts raising to the section where water is having maximum height is known as the length of the back water curve

17.Define back water

The profile of the raising water on the upstream side of the dam is called as back water curve.

18.Define hydraulic jump

The raise of water level which takes place due to the transformation of the unstable shooting flow ( super critical flow ) to the stable Streaming flow ( sub critical flow ) is called hydraulic jump.

19. Define cavitations

cavitations is defined as phenomenon of formation of vapour bubbles in a region of a flowing liquid where the pressure in the liquid is falls below than vapour pressure and sudden collapsing of these vapour bubbles in a region of higher pressure.

20. 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.

The difference between head race level and tail race level when no water is flowing is know as gross 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

23. Define Hydraulic Efficiency:

It is defined as the ratio of power delivered to the runner to the power supplied at the inlet.

24. Define 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.

25. Define 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.

26.Define over all efficiency

It is defined as the ratio of shaft power by water power

27.Explain impulse turbine

If at the inlet of the turbine the energy available is only kinetic energy the turbine is known as impulse turbine.

28.Explain Reaction turbine

if at the inlet of the turbine the water possesses kinetic energy as well as pressure energy the turbine is known as reaction turbine.

29.Explian tangential flow turbine

If the water flows along the tangent of the runner, the turbine is known as the tangential flow turbine.

If the water flows in the radial direction through the runner the turbine I called radial flow turbine.

If the water flows radially from inwards to outwards the turbine is known as outward radial flow turbine.

32.Define axial flow turbine

If the water flows through the runner along the direction parallel to the axis of

rotation of the runner the turbine is called axial flow turbine.

33.what is Pelton wheel:

Pelton wheel or Pelton turbine is a tangential flow impulse turbine. The water strikes the bucket along the tangent of the runner . The energy available at the inlet of the Turbine is only kinetic energy.This turbine is used for high heads.

34.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.

35.What is jet ratio?

It is the ratio of pitch diameter (D) to the diameter of jet (d).

36.What is Draft tube?

A tube or pipe of gradually increasing area is used for discharging water from the exit of the tubine to the tail race is called draft tube.

37.Define Degree of Reaction (R)

It is defined as the ratio of change of pressure energy inside the runner to the change of total energy out side the runner.

This means the angle made by absolute velocity with the tangent on the wheel is 90 and the component of whirl velocity is zero.

39.Define Francis turbine:

Inward flow reaction turbine having radial discharge at outlet is known as francis turbine

40.Define propeller turbine:

This is an example of axial flow reaction turbine . Here the vanes are fixed to the hub and are not adjustable.

41.Define Kaplan turbine:

This is an example of axial flow reaction turbine. Here the vanes are not fixed to the hub and are adjustable.

42.What are the use 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 usefull pressure energy

43.What are types of draft tube?

1.conical draft tube

2.simple elbow tube

4.draft tube with circular inlet and rectangular outlet.

44.What are the types of characteristic curves

1.Main characteristic curves

2.Operating characteristic curve

3.Muschel characteristic curves

45.What is specific speed of the turbine?

It is defined as the speed of a turbine which will develop unit power under unit head.

46.Define unit quantities;

Unit quantities are the quantities which are obtained when the head on the turbine are unity.

47.Explain about characteristic curves of a hydraulic turbine

Characteristic curves of a hydraulic turbine are the curves with the help of which the exact behaviour and performance of the turbine under different working conditions can be known.

48.What is meant by conveyance of the channel?

The conveyance of the channel is denoted by k and is given by k=AC (m).

49.Define the term most economical section:

A section of the channel is said to be most economical when the cost of construction of the channel is minimum. But the cost of construction mainly depend up on the excavation and lining to keep the cost minimum ,the wetted perimeter for a given discharge should be minimum.

50.What are the conditions of rectangular channel of best section?

The two conditions are breadth is equal to two times the depth (b=2d) and hydraulic mean depth is equal to half the depth (m=d/2)

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