Dom 1st Series Qp.docx

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MES INSTITUTE OF TECHNOLOGY & MANAGEMENT, CHATHANNOOR

ME-S6

SECOND SERIES EXAMINATION, APRIL 2019 ME304 DYNAMICS OF MACHINERY Time: 2 Hrs Max Marks: 40

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Answer any two questions

1.

a. Differentiate between the usage of flywheel in engines and punching presses.

4marks

b. There will be no effect of gyroscopic-couple acting on the body of a ship due to rolling. Why? 4marks c. A riveting machine is driven by a constant torque 3 kW motor. The moving parts including the flywheel are equivalent to 150 kg at 0.6 m radius. One riveting operation takes 1 second and absorbs 10 000 N-m of energy. The speed of the flywheel is 300 r.p.m. before riveting. Find the speed immediately after riveting. How many rivets can be closed per minute? 12 marks 2.

a. Define Swaying couple.

3marks

b. A single cylinder, single acting, four stroke gas engine develops 20 kW at 300 r.p.m. The work done by the gases during the expansion stroke is three times the work done on the gases during the compression stroke, the work done during the suction and exhaust strokes being negligible. If the total fluctuation of speed is not to exceed ± 2 per cent of the mean speed and the turning moment diagram during compression and expansion is assumed to be triangular in shape, find the moment of inertia of the flywheel. 10marks c. An aeroplane makes a complete half circle of 50 metres radius, towards left, when flying at 200 km per hr. The rotary engine and the propeller of the plane has a mass of 400 kg and a radius of gyration of 0.3 m. The engine rotates at 2400 r.p.m. clockwise when viewed from the rear. Find the gyroscopic couple on the aircraft and state its effect on it. 7marks 3.

a. What are the applications of gyroscopic couple? Write down the expression for gyroscopic couple acting on the aeroplane? 3marks b. Explain about different types of motions of a navel ship, while considering gyroscopic couple? 5marks c. The mass of the turbine rotor of a ship is 20 tonnes and has a radius of gyration of 0.60 m. Its speed is 2000 r.p.m. The ship pitches 6° above and 6° below the horizontal position. A complete oscillation takes 30 seconds and the motion is simple harmonic. Determine the following: 1. Maximum gyroscopic couple, 2. Maximum angular acceleration of the ship during pitching, and 3. The direction in which the bow will tend to turn when rising, if the rotation of the rotor is clockwise when looking from the left. 12marks

4.

a. Explain about the effect of gyroscopic couple acting on a two wheel drive?

4marks

b. Define Hammer blow. How can reduce the effect of hammer blow in a locomotive? 4marks c. A four wheeled motor car of mass 2000 kg has a wheel base 2.5 m, track width 1.5 m and height of centre of gravity 500 mm above the ground level and lies at 1 metre from the front axle. Each wheel has an effective diameter of 0.8 m and a moment of inertia of 0.8 kg-m2 . The drive shaft, engine flywheel and transmission are rotating at 4 times the speed of road wheel, in a clockwise direction when viewed from the front, and is equivalent to a mass of 75 kg having a radius of gyration of 100 mm. If the car is taking a right turn of 60 m radius at 60 km/h, find the load on each wheel. 12marks

Scheme of valuation a. Differentiate usage of flywheel in engines and punching presses. 2+ 2 marks b. Explain about rolling action in ship 4marks c. Find Speed of the flywheel immediately after riveting N = 257.6 r.p.m. Number of rivets that can be closed per minute 18 rivets 6+6 = 12 marks 2. a. Swaying couple. 3marks b. Find Tmean = 637Nm , ∆E = 10081Nm, I = 255.2 kg-m2 3+4+3 = 10 marks c. Find I= 36kg-m2, ωP = 1.11 rad/s ,C= 10.046 kN-m , explain gyroscopic couple effect on aeroplane. 2+2+3+3 = 10marks 3. a. applications of gyroscopic couple? Write down the expression for gyroscopic couple acting on the aeroplane 2+1 = 3marks b. Different types of motions of a navel ship pitching, steering, rolling 5 marks c. 1. Maximum gyroscopic couple, 4marks 2. Maximum angular acceleration of the ship during pitching, 4marks 3. Gyroscopic effects 3marks 4. a. gyroscopic couple acting on a two wheel 4marks b. Explain Hammer blow. and how can reduce it in a locomotive 2+2 =4marks c. Find : W1= 5886 N, =W2 = 3924 N ,ωW = 41.675 rad /s , ωP = 0.278 rad /s, CW = 37.1Nm, P / 2 = 12.37 N, 4marks CE = 34.7 Nm, F / 2 = 6.94 Nm, CO = 4631.5Nm, Q / 2 = 1543.83N, 4marks Load on the front wheel 1= 4322.86 N, wheel 2= 7435.26 N, wheel 3= 2374.74 N, wheel 4= 5487.14 N 4marks . 4+4+4 =12marks 1.

Prepared by

Academic Coordinator

HOD