JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B. Tech II Year FLUID MECHANICS AND HYDRAULIC MACHINERY Previous Question Paper (September/October - 2023 - R15)

Define Kinematic Viscosity and mention its significance.

The pressure in the tyre is gauge pressure or absolute pressure. Justify.

Define the equation of continuity.

Explain the significance of various terms in Bernoulli’s equation.

Write an expression for force exerted by jet on stationary vertical plate?

Write about hydrodynamic force?

Define hydraulic efficiency of a turbine.

Write about work done and efficiency?

Why pumps are generally less efficient than turbines.

Define NPSH.

The space between two square flat parallel plates is filled with oil. Each side of the plate is 60 cm. The thickness of the oil film is 12.5 mm. The upper plate, which moves at 2.5 metre per sec, requires a force of 98.1 N to maintain the speed. Determine: (i) The dynamic viscosity of the oil in poise, and (ii) The kinematic viscosity of the oil in stokes if the specific gravity of the oil is 0.95.

An oil of viscosity 5 poise is used for lubrication between a shaft and sleeve. The diameter of the shaft is 0.5 m and it rotates at 200 r.p.m. Calculate the power lost in oil for a sleeve length of 100 mm. The thickness of oil film is 1.0 mm.

Derive the Euler’s equation of motion along a streamline.

Explain (i) Stream line ii) Irrotational Flow iii) Streak line.

A pumping plant forces water through a 500 mm diameter main, the friction head being 30 metres. In order to reduce the power consumption, it is proposed to lay another main of appropriate diameter along the side of the existing one, so that two pipes may work in parallel for the entire length and reduce the friction head to 10 metres only. Find the diameter of the new main if with the exception of the diameter, it is similar to the existing one in every respect.

A flat plate of 2.0 m width and 4.0 m length is kept parallel to air flowing at a velocity of 5 m/s. Determine the length of plate over which the boundary layer is laminar, shear at the location which boundary layer ceases to be laminar and total force on both sides on that portion of plate where the boundary layer is laminar. Take ρ = 1.2 kg/m³ and ν = 1.47×10^-5 m²/s.

Discuss displacement thickness, energy thickness and momentum thickness.

What do you understand by Boundary Layer? Explain the development of Boundary layer over a flat plate.

Derive the equation for the impact of jet striking a curved plate at the centre when the plate is stationary.

A 15 cm diameter jet of water with a velocity of 15 m/s strikes a plane normally. If the plate is moving with a velocity of 6 m/s in the direction of the jet calculate the work done per second on the plate and the efficiency (η) of energy transfer.

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

What are the different factors to be considered while selecting the site for hydroelectric power plant?

A pelton wheel is required to develop 1800 kW under a net head of 200 m at a speed of 480 rpm. Calculate: (i) the mean diameter of the wheel. (ii) the diameter of the jet. (iii) the number of jets required, assuming the data. Given below: Coefficient of velocity jet, C_v = 0.98, Speed ratio φ = 0.48. The jet diameter ‘d’ to be 1/12 of the mean diameter of the wheel D.

A turbine develops 7725 kW under a head of 28 metres at 140 rpm. Calculate the specific speed of the turbine and state the type of turbine.

A centrifugal pump discharge 560 liters of water per second has to develop a head of 10 meters, the speed of rotation of the impeller being 700rpm. The manometric efficiency is 85% and the loss of head in the pump due to friction is 0.025 v₁² meters of water, where v₁ is the velocity with which the water leaves the impeller. Assume that the velocity of flow through the impeller is constant at 2.50 meters per second and that there is no velocity of whirl at inlet. Determine (i) The diameter of the impeller (ii) the outlet area (iii) The vane angle at the outlet edge of the impeller.

Describe with the help of diagrams the variable speed and constant speed performance curves of a centrifugal pump.