JNTU
JNTU B.Tech II FLUID MECHANICS II Previous Question Paper (May - 2019 - R16)
Note: This question paper contains two parts A and B. Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B consists of 5 Units. Answer any one full question from each unit.
Part A
Find the discharge through a rectangular channel of width 2 m, having bed slope of 4 in 8000. The depth of flow is 1.5 m and take the value of N in Manning’s formula as 0.012.
Answer
Given: Width (B) = 2 m, Depth (y) = 1.5 m, Slope (S) = 4/8000 = 0.0005, Manning's N = 0.012. Area (A) = B × y = 2 × 1.5 = 3 m2. Wetted perimeter (P) = B + 2y = 2 + 2(1.5) = 5 m. Hydraulic radius (R) = A/P = 3/5 = 0.6 m. Using Manning's formula: V = (1/N) × R2/3 × S1/2 = (1/0.012) × (0.6)2/3 × (0.0005)1/2 = 83.33 × 0.711 × 0.02236 = 1.325 m/s. Discharge (Q) = A × V = 3 × 1.325 = 3.975 m3/s.
What do you understand by surges and how would you classify them?
Answer
A surge is a sudden change in the depth of flow in an open channel caused by a rapid change in the discharge or boundary conditions. They are classified into:
- Positive surges: Where the depth of flow increases (e.g., a bore).
- Negative surges: Where the depth of flow decreases (e.g., a sudden opening of a sluice gate).
State the advantages of model testing.
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List out the merits and demerits of distorted models.
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Find the force exerted by a jet of water of diameter 65 mm on a stationary flat plate, when the jet strikes the plate normally with velocity of 20 m/s.
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A jet of water of 4.5 cm diameter, moving with a velocity of 20 m/s, strikes a hinged square plate of weight 98.1 N at the centre of the plate. The plate is of uniform thickness. Find the angle through which the plate will swing.
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Define specific speed? State its significance in the study of hydraulic machines.
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Differentiate between an inward and an outward flow reaction turbine.
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What are the advantages of centrifugal pump over reciprocating pumps?
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Explain the terms-load factor, utilization factor and capacity factor.
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Part B
State and prove the conditions under which the rectangular section of open channel will be most economical.
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Explain the term hydraulic jump. Derive an expression for the depth of hydraulic jump in terms of the upstream Froude number.
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What do you mean by dimensionless numbers? Describe any four dimensionless numbers.
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In the model test of a spillway the discharge and velocity of flow over the model were 2.5 m3/s and 1.5 m3/s respectively. Calculate the velocity and discharge over the prototype which is 36 times the model size.
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Describe Buckingham’s method or π-theorem to formulate a dimensionally homogeneous equation between the various physical quantities effecting a certain phenomenon.
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Show that for a curved radial vane, the work done per second is given by, ρaV1 [Vw1 u1 ± Vw2 u2]
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A jet of water 75 mm diameter having a velocity of 20 m/s, strikes normally a flat smooth plate. Determine the thrust on the plate (a) if the plate is at rest, (b) if the plate is moving in the same direction as the jet with a velocity of 5 m/s. Also find the work done per second on the plate in each case and the efficiency of the jet when the plate is moving.
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What is governing and how it is accomplished for different types of water turbines?
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A pelton wheel has to be designed for the following data. Power to be developed = 6,000 kW. Net head available = 300 m; speed = 550 r.p.m; Ratio of jet diameter to wheel diameter = 1/10; and overall efficiency = 85%. Find the number of jets; diameter of the jet; diameter of the wheel and the quantity of water required.
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What is the difference between single-stage and multistage pumps? Describe multistage pump with impeller in parallel.
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A three stage single centrifugal pump has impeller 400 mm in diameter and 20 mm wide at outlet. The vanes are curved back at the outlet at 450 and reduced the circumferential area by 10 percent: The manometric efficiency is 90 percent and the overall efficiency is 80 percent. The pump is running at 1000 r.p.m. and delivering 0.05 m3/s. Determine:
Head generated by the pump
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Shaft power required to run the pump
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