Important Question And Answer: civil - Applied Hydraulic Engineering - Part 2

51.Write down the conditions for the most economical trapezoidal channel?

1.Half the top width is equal to one of sloping side (b+2 nd)/2=d?(1+n2)

2.Hydraulic mean depth is equal to half the depth.

52.Write down the conditions of most economical circular channel with maximum velocity?

?=128 o 45'

d=0.81D

m=0.3D

53.What do you mean by open channel flow?

1.Open channel flow has a free surface which is subjected to atmospheric pressure.

2.In open channel flow the cross section is irregular.

54.What do you mean by pipe flow?

1.Pipe flow has no free surface and subjected to hydraulic pressure only.

2.The cross section of the flow is fixed

55.List the instrument used to measure open channel flow

1.pitot tube

2.ultrasonic flow instrument.

3.Dropper instrument

4.Gurley instrument.

56.What is the best side slope for trapezoidal channel ?

?=60 o is the best side slope for trapezoidal channel.

57.what do mean by M1 profile?

The most common of all gradually varying flow is of M1 type which is a sub critical flow condition obstructions to flow such as wiers, dams etc…which produce M1 profile.

58.What are the types of flow profile? Mild slope profile

Steep slope profile Critical slope profile Horizontal bed profile Adverse slope profile

59.What do you mean by M2 profile?

The M2 profile occurs at a sudden drop in the bed of the channel in to the ponds or pools or lakes.

60.What do mean by M3 profile?

The M3 profile occurs the flow yielding from a spillway or a sluice gate. 61.What is speed ratio?

U1=??(2gH)

Where U1 - tangential velocity of wheel at inlet

? -speed ratio

H - Head of the turbine.

62.What do you mean by coefficient of velocity?

V1=Cv (2gH)      

V1 = velocity of jet       

Cv     = coefficient of velocity 

H = head of the turbine.

63.What are the main parts of pelton wheel turbine?   

1.       nozzle and flow regulating arrangement    

2.       runner with buckets      

3.       casing

4.       breaking jet

64.What are the main mechanism of Radial flow reaction turbine?

1.casing

2.guide mechanism

3.runner

4.draft tube

65.Define Multistage pump:

If centrifugal pump consists of two or more impellers the pump is called multistage pump. To produce a high head impellers are connected

in series .To produce high discharge impellers are connected in parallel.

66.Define Manometric head:

Manometric head is the head against which a centrifugal pump has to work.

Hm = H_s +h_d +H_fs +H_fd + (vd²/2g)

- manometric head

Hs - suction head

Hd - delivery head

Hfs - friction head loss in suction pipe

Hfd - friction head loss in delivery pipe

67.What is Net Positive Suction Head (NPSH) ?

NPSH is defined as the total head required to make liquid flow through suction pipe to pipe impeller.

68.Define slip of a reciprocating pump and negative slip:

Slip is defined as the difference between theoretical discharge and actual discharge. If actual discharge is greater than theoretical discharge negative value is found this negative value is called negative slip.

69.What do you know coefficient of  discharge?

It is defined as the ratio of actual discharge by theoretical discharge. It is denoted By Cd.

70.What do you know Drop down curve?

The water surface has a convex profile upwards this curve is called drop down curve.

71.What is separation of reciprocating pump?

If the pressure in the cylinder is below the vapour pressure , dissolved gasses will be liberated from the liquid and cavitations will takes place . The continuous flow of liquid will not exit which means separation of liquid takes place. The pressure at which separation takes place is called separation pressure and head corresponding to the separation pressure is called separation pressure head.

72.What is an indicator diagram?

Indicator diagram is the graph between the pressure head and distance traveled by the piston from inner dead center for one complete revolution.

73.What is Air vessel?

Air vessel is a closed chamber containing compressed air in the top portion and liquid at the bottom of the chamber . It is used to obtain a continuous supply of water at uniform rate to save a considerable amount of work and to run the pump at high speed with out separation.

74.What are the assumptions of gradually varying flow profile?

1.Pressure distribution at any section is assumed to be hydrostatic.

2.The velocity distribution at the channel section is fixed

3.The channel is prismatic

4.The roughness coefficient is independent of the depth of flow.

75.What the two cases where distance of the normal depth of flow does not exit?

(a)When the channel bed is horizontal

(b) When the channel bed has a adverse slope.

76.What are the methods used for finding gradually varying flow profile?

1.Direct integration method

2.Numerical method

3.Graphical representation method.

77.What are the classification of hydraulic turbine according to the type of energy at inlet ?

(a)Impulse turbine and  

(b Reaction turbine       

78.What are the types of turbine according to direction of flow through runner?        

(a)Tangential flow turbine      

(b)     Radial flow turbine       

(c)Axial flow turbine     

(d)     Mi  ed flow turbine       

79.What are the types of turbine according to the head at the inlet of the turbine?

(a)high head turbine

(b) medium head turbine

(c)low head turbine

80.What are the types of turbine according to the specific speed of the turbine?

(a)Low specific speed turbine

(b) Medium specific speed turbine

(c)High specific speed turbine.

81.Write down the expression for energy loss due to hydraulic jump?

HL  =   (d2-d1)³  /  (4d1d₂)

Where

HL - energy loss due to hydraulic jump D2 - depth of flow after the jump

D1 -- depth of flow before the jump 82.What do you mean by length of hydraulic jump?

This is defined as the length between the two sections where one section is taken before the hydraulic jump and the second section is taken immediately after the jump.

83.What are the classification of flow in channels?

1.steady flow and un steady flow.

2.uniform flow and non uniform flow.

3.Laminar flow and turbulent flow and

4.sub critical , critical and super critical flow.

84.What are the types of Non uniform flow?

(i)      Rapidly Varied Flow (R.V.F)

(ii)     Gradually Varied Flow (G.V.F)

85.What do you know about laminar and turbulent flow?

Laminar flow: The flow in open channel is said to be laminar if the Reynolds number( Re) is less than 500

Turbulent flow: If the Reynolds number is greater than 2000 it is called turbulent flow.

86.What do you mean by specific energy curve?

It is defined as the curve which shows the variation of specific energy with respect to depth of flow.

87.Write the manometric efficiency of the pump?                  

Manometric efficiency  = (gHm)/(Vw2U2)          

Where                           

Hm -manometric head           

88.Write the expression for over all efficiency ? over all efficiency           

= (?g QHm)/(1000 x P) Where         

Hm - manometric head          

P       - power                

89.What is the minimum speed for starting the centrifugal pump? 

N=(120 ?manVw² D)/(?(D2²-D1²) Where

?man - manometric efficiency

Vw² _- Whirl at out let of the turbine D2 - diameter of impeller at out let

90. Write down the use of centrifugal pump?

1.Used in deep sump and basement

2.The high discharge capacity

3.It is driven by electric motors