Jawaharlal Nehru Technological University Hyderabad B.Tech II MECHANICS OF FLUIDS AND HYDRAULIC MACHINES Previous Question Paper (February -2024 - R13)

Determine the intensity of shear of an oil having viscosity = 1 Poise. The oil is used for lubricating the clearance between a shaft of diameter 10 cm and its journal bearing. The clearance is 1.5 mm and the shaft rotates at 150 r.p.m.

An inverted U-tube manometer is connected to two horizontal pipes A and B through which water is flowing. The vertical distance between the axes of these is 30 cm. When an oil of specific gravity 0.8 is used as a gauge fluid, the vertical heights of water columns in the two limbs of the inverted manometer (when measured from the respective center lines of the pipes) are found to be same and equal to 35 cm. Determine the difference of pressure between the pipes.

What are the gauge pressure and absolute pressure at a point 3 m below the free surface of a liquid having a density of 1.53 × 10³ kg/m³, if the atmospheric pressure is equivalent to 750 mm of mercury? The specific gravity of mercury is 13.6 and density of water = 1000 kg/m³.

What is the difference between U-tube differential manometers and inverted U-tube differential manometers? Where are they used?

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 a 20 cm pipe, if the average velocity in a 30 cm diameter pipe is 2 m/s.

A 45^o reducing bend is connected in a pipeline, the diameters at the inlet and outlet of the bend being 600 mm and 300 mm respectively. Find the force exerted by water on the bend if the intensity of pressure at the inlet to bend is 8.829 N/cm² and the rate of flow of water is 600 litres/s.

Write the assumptions in Bernoulli’s theorem.

Distinguish between: (i) Steady flow and unsteady flow, (ii) uniform and non-uniform flow, (iii) rotational and irrotational flow.

A plate of 600 mm length and 400 mm wide is immersed in a fluid of sp. gr. 0.9 and kinematic viscosity = 10^-4 m²/s. The fluid is moving with a velocity of 6 m/s. Determine (i) boundary layer thickness, and (ii) drag force on one side of the plate.

What do you mean by separation of boundary layer? What is the effect of pressure gradient on boundary layer separation?

Oil with a free stream velocity of 2 m/s flows over a thin plate 2 m wide and 2 m long. Calculate the boundary layer thickness and the shear stress at the trailing endpoint and determine the total surface resistance of the plate. Take specific gravity as 0.86 and kinematic viscosity as 10^-5 m²/s.

The rate of flow of water through a horizontal pipe is 0.2 m³/s. The diameter of the pipe which is 175 mm is suddenly enlarged to 350 mm. The pressure intensity in the smaller pipe is 11.772 N/cm². Determine: (i) Loss of head due to sudden enlargement, (ii) pressure intensity in the large pipe.

Water is flowing through a pipe at the end of which a nozzle is fitted. The diameter of the nozzle is 100 mm and the head of water at the center nozzle is 100 m. Find the force exerted by the jet of water on a fixed vertical plate. The coefficient of velocity is given as 0.95.

A Pelton wheel is having a mean diameter of 1 m and is running at 1000 r.p.m. The net head on the Pelton wheel is 700 m. if the side clearance angle is 15^o and discharge through nozzle is 0.1 m³/s, find: (i) Power is available at the nozzle, and (ii) Hydraulic efficiency of the turbine.

A 7.5 cm diameter jet having a velocity of 30 m/s strikes a flat plate, the normal of which inclined at 45^o to the axis of the jet. Find the normal pressure on the plate: (i) when the plate is stationary, and (ii) when the plate is moving with a velocity of 15 m/s and away from the jet. Also determine the power and efficiency of the jet when the plate is moving.

What is a draft tube? Why is it used in a reaction turbine? Describe with a sketch two different types of draft tubes.

A centrifugal pump delivers water against a net head of 14.5 meters and a design speed of 1000 r.p.m. The vanes are curved back to an angle of 30^o with the periphery. The impeller diameter is 300 mm and the outlet width is 50 mm. Determine the discharge of the pump if manometric efficiency is 95%.

Define the terms: suction head, delivery head, static head, and manometric head.

What is a reciprocating pump? Describe the principle and working of a reciprocating pump with a neat sketch. Why is a reciprocating pump not coupled directly to the motor? Discuss the reason in detail.

How does the specific speed of a centrifugal pump differ from that of a turbine?