Jawaharlal Nehru Technological University Hyderabad B.Tech II MECHANICS OF FLUIDS AND HYDRAULIC MACHINES Previous Question Paper (December - 2017 - R15)

Distinguish between cohesion and adhesion.

Explain absolute pressure and gauge pressure.

What is meant by rotational and irrotational flows?

Explain surface and body forces.

Explain critical Reynold’s number as applied to boundary layer.

Explain HGL and TEL with the help of a figure.

What is a surge tank?

With examples, differentiate hydrostatic and hydrodynamic force.

What is NPSH?

Explain the classification of pumps.

Differentiate between: (i) Liquids and gases, (ii) Real fluid and ideal fluids, (iii) Specific weight and specific volume of a fluid.

Determine the intensity of shear of an oil having viscosity = 1.2 poise and is used for lubrication in the clearance between a 10 cm diameter shaft and its journal bearing. The clearance is 1.0 mm and shaft rotates at 200 r.p.m.

What is the difference between dynamic viscosity and kinematic viscosity. State their units of measurements.

Glycerin has a density of 1260 kg/cu.m and a kinematic viscosity of 0.00183 m²/sec. What shear stress is required to deform this fluid at a strain rate of 10⁴/s?

Define the terms: (i) Path line (ii) Streak line (iii) Stream line, and (iv) Stream tube.

Water is flowing through a pipe having diameters 30 cm and 15 cm at the bottom and upper end respectively. The intensity of pressure at the bottom end is 29.43 N/cm² and the pressure at the upper end is 14.715 N/cm². Determine the difference in datum head if the rate of flow through pipe is 50 lit/s.

Define the equation of continuity. Obtain an expression for continuity equation for a three dimensional flow.

A 40 cm diameter pipe, conveying water, branches into two pipes of diameter 30 cm and 20 cm respectively. If the average velocity in the 40 cm diameter pipe is 3 m/s. find the discharge in this pipe. Also determine the velocity in 20 cm pipe if the average velocity in 30 cm diameter pipe is 2 m/s.

Explain with the help of a neat sketch, the formation of boundary layer over a flat plate.

A horizontal pipe of diameter 400 mm is suddenly contracted to a diameter of 200 mm. The pressure intensities in the large and smaller pipe is given as 14.715 N/cm² and 12.753 N/cm² respectively. If Cc = 0.62, find the loss of head due to contraction. Also determine the rate of flow of water.

How is the drag and lift force caused on a body immersed in a moving fluid?

A pipe of diameter 300 mm and length 1000 m connects two reservoirs, having difference of water levels as 15 m. Determine the discharge through the pipe. If an additional pipe of diameter 300 mm and length 600 m is attached to the last 600 m length of the existing pipe, find the increase in the discharge. Take f = 0.02 and neglect minor losses.

State and explain momentum equation. What are the practical applications of it?

A Pelton wheel is to be designed for the following specifications. Power = 735.75 kW S.P, Head = 200 m, Speed = 800 r.p.m., η° = 0.86 and jet diameter is not to exceed one-tenth the wheel diameter. Determine: (i) Wheel diameter, (ii) The number of jets required, and (iii) Diameter of the jet. Take Cv=0.98 and speed ratio =0.45.

Derive an expression for the force exerted by a jet of water on an inclined fixed plate in the direction of the jet.

A Kaplan turbine working under a head of 25 m develops 16000 kW shaft power. The outer diameter of the runner is 4 m and hub diameter is 2 m. The guide blade angle is 35°. The hydraulic and overall efficiency are 90% and 85% respectively. If the velocity of whirl is zero at outlet, determine runner vane angles at inlet and outlet, and speed of turbine.

Define a centrifugal pump. Explain the working of a single-stage centrifugal pump with sketches.

Find the number of pumps required to take water from a deep well under a total head of 156 m. Also the pumps are identical and are running at 1000 r.p.m. The specific speed of each pump is given as 20 while the rated capacity of each pump is 150 litre/s.

Differentiate between the volute casing and vortex casing for the centrifugal pump.

A centrifugal pump runs at 1540 rpm and discharges 120 lps against a head of 25 m. If the diameter of the impeller is 25 cm and its width is 8 cm, find the vane angle at the outer periphery. The manometric efficiency of the pump is 75%.