JNTU B.Tech II FLUID MECHANICS AND HEAT TRANSFER Previous Question Paper (December - 2018 - R13)

The stream function ψ = 4xy in which y is in cm² per second and x and y are in meters describe the incompressible flow between the boundary which is a curve of equation xy=3, and point B lies on curve, and point A lies on x axis, at x=3. Calculate:

a) velocity at B

b) Convective acceleration at B

c) Flow per unit width across AB.

The velocity component in a two dimensional flow field for an incompressible fluid are expressed as u = 2/3 x³ - 2xy²; v = 2x²y - 2/3 y³

a) Show that these functions represent a possible case of an irrotational flow.

b) Obtain an expression for stream function.

c) Obtain an expression for velocity potential ɸ.

Derive the Euler’s equation of motion subjected to pressure and body forces in all the three perpendicular directions.

A 0.3 m by 0.15 m venturimeter is mounted on a vertical pipe with flow upwards. 63 lit/s of oil of specific gravity 0.8 and dynamic viscosity 1 poise flows through the pipeline. The throat section is 0.1 m above the inlet section. What is the pressure difference between the inlet and the throat?

A thin walled copper tube of outside metal radius r = 0.01 m carries steam at 400 K. It is inside a room where the corresponding air temperature is 300K. The tube is insulated with magnesia insulation of approximate thermal conductivity 0.07 W/m K.

Steady state one dimensional conduction occurs in a rod of constant thermal conductivity k and of variable cross section area A_x = A_oe^ax where A_o and a are constant. The length of the rod is L. The lateral surface of the rod is well insulated. The surfaces at x= 0 and x = L are kept at constant temperatures of T1 and T2 respectively. Find the expressions for:

What are the physical implications of the dimensionless numbers?

Engine oil at 70⁰C flows with a velocity of 2 m/s over a 4 m long flat plate whose temperature is 20⁰C. Determine the rate of heat transfer per unit width of the plate. The properties of engine oil at mean film temperature of 45⁰C are given as ρ = 870 kg/m³, ν = 2.4 × 10^-4 m²/s, k = 0.14 W/m K, Pr = 2.8 × 10³.

A vertical plate 60 cm high and 30 cm wide is maintained at a temperature of 95⁰C in a room where the air is 20⁰C and 1 atm. The walls of the rooms are also at 20⁰C. Assume that ε = 0.8 for the plate how much radiant heat is lost by the plate.

Water enters counter flow double pipe heat exchanger at 35⁰C flowing at the rate of 0.8 kg/s. It is heated by oil (c_p = 1.88 kJ/kg K) flowing at the rate of 1.5 kg/s from an inlet temperature of 120⁰C. For an area of 15 m² and overall heat transfer coefficient of 350 W/m² K, determine the total heat transfer rate. Take the specific heat of water as 4.18 kJ/kg K.