JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD B.Tech II Year II Semester DYNAMICS OF MACHINES Previous Question Paper (May - 2019 - R16)

The rotor of the turbine of a ship has a mass of 2500 kg and rotates at a speed of 3200 rpm counter-clockwise when viewed from stern. The rotor has radius of gyration of 0.4m. Determine the gyroscopic couple and its effect when (a) The ship steers to the left in a curve of 80m radius at a speed of 15 knots (b) The ship pitches 5 degrees above and 5 degrees below the normal position and the bow is descending with its maximum velocity. The pitching motion is simple harmonic with a periodic time of 40 seconds.

Discuss the effect of gyro couple on Aero plane while taking right turn. An aero plane makes a complete half circle of 50 meters radius, towards left when flying at 200 km/hr. The rotary engine and the propeller of the plane have a mass. Find the gyroscopic couple on the plane and state its effect on it. What will be the effect, if the aero plane turns to its right instead of to the left?

A conical pivot with angle of cone as 100 degrees supports a load of 18 KN. The external radius is 2.5 times the internal radius. The shaft rotates at 150 rpm. If the intensity of pressure is to be 300 KN/m2 and coefficient of friction as 0.05, what is the power lost in working against the friction?

In a belt transmission dynamometer, the driving pulley rotates at 300 rpm. the distance between the centre of the driving pulley and the dead mass is 800mm. the diameter of each of the driving as well as the intermediate pulleys is equal to 360 mm. find the value of the dead mass required to maintain the lever in a horizontal position when the power transmitted is 3KW. Also find its value when the belt just begins to slip on the driving pulley, coefficient of friction being 0.25 and maximum tension in the belt 1200N.

A Hartnell governor having a central sleeve spring and two right-angled bell crank levers operates between 290 r.p.m. and 310 r.p.m. for a sleeve lift of 15 mm. The sleeve arms and the ball arms are 80 mm and 120 mm respectively. The levers are pivoted at 120 mm from the governor axis and mass of each ball is 2.5 kg. The ball arms are parallel to the governor axis at the lowest equilibrium speed. Determine : (a) loads on the spring at the lowest and the highest equilibrium speed and (b) stiffness of the spring.

The torque exerted on the crank-shaft of a two stroke engine is given by the equation: T (N-m) = 14500 + 2300 sin 2θ – 1900 cos 2θ Where θ is the crank angle displacement from the inner dead centre. Assuming the resisting torque to be constant, determine: (a) the power developed when the speed is 150 r.p.m and the moment of inertia of the flywheel if the total fluctuation of speed is not to exceed 1% of the mean speed. (b) the angular acceleration of flywheel when the crank has turned through 30 degrees from the inner dead centre.

A shaft carries four rotating masses A, B, C and D in this order along its axis. The mass A may be assumed to be concentrated at radius of 18 cm, B of 24 cm, C of 12 cm and D of 15 cm. The masses of B, C and D are 30 kg, 50 kg and 40 kg respectively. The planes containing B and C are 30 cm apart. The angular spacing of the planes containing C and D are 90 and 210 degrees respectively relative to B measured in the same plane. If the shaft and masses are to be in complete dynamic balance, find: (a) the mass and the angular position of mass A (b) the position of planes A and D.

The cranks of a two-cylinder uncoupled inside cylinder locomotive are at right angles and are 300 mm long. The distance between the center lines of the cylinder is 650 mm. The wheel centre lines are 1.6 m apart. The reciprocating mass per cylinder is 300 kg. The driving wheel diameter is 1.8 m. If the hammer blow is not to exceed 45 kN at 100 km/hr, determine: (a) the fraction of the reciprocating masses to be balanced, (b) the variation in tractive effort. (c) the maximum swaying couple.

Describe the method of finding the natural frequency of torsional vibrations for a three rotor system.

The vibrations of a cantilever are given by y= yl(1- cos(pi*x/2l)). Calculate the frequency with following data for the cantilever using Rayleigh’s method. Modulus of elasticity of the material 2×10^11 N/m2. Second moment of area about bending axis 0.02 m4, mass = 6× 10^4 kg, length = 30m.