Fluid Mechanics: Dec’17 - irfansir.in · Fluid Mechanics: Dec’17 Sem ... What is Kutzbach’s criterion for degree of freedom of plane mechanism? In what ways it differs from

Fluid Mechanics: Dec’17

Sem - VI: Mech / Auto

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Model Paper

K.O.M - Revised Syllabus

Total Marks: 80

N.B

Question No. 1 is compulsory.

Answer any three out of remaining five questions.

Assume suitable data, if required; but justify the same.

Q 1. Attempt any four [20m]

a) What do you mean by Coriolis component of acceleration? With an example explain its direction. b) What is Kutzbach’s criterion for degree of freedom of plane mechanism? In what ways it differs from

Grubler’s criterion? c) In case of gears, prove that; the velocity of sliding is proportional to the distance of the point of contact

from the pitch point. d) Explain: How an Elliptical Trammel can trace ellipse as well as circle. e) Derive Fundamental Equation of Correct Steering.

Q 2. (a) In the Epicyclic Gear train as shown in Fig - 1, a gear C which has teeth cut internally as well as externally is free to rotate on an arm driven by the shaft S1. It meshes with the casing D and internally with the pinion B. The gears have following number of teeth: TB = 24. TC = 32 and TD = 48. Find the velocity ratio between;

i. S1 and S2, when D is fixed. ii. S1 and D, when S2 is fixed.

[10m]

What will be the holding torque required to fix the casing D, if a torque of 300 Nm is applied to shaft S1. Q 2. (b) 2.5 kW power is transmitted by an open belt drive. The linear velocity of the belt is 2.5 m/s. angle of lap on the smaller pulley is 165°. Take coefficient of friction as 0.3. Determine the effect on power transmission for the following cases;

i. Initial tension in the belt is increased by 8%. ii. Angle of lap is increased by 8% by the use of idler pulley for the same speed and same tension on

tight side. iii. Coefficient of friction is increased by 8% by suitable dressing on the friction surface of the belt.

[10m]

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Q 3. (a) The mechanism of a warping machine, as shown in the figure, has the following dimensions: O1A = 100mm, AC = 700mm, BC = 200mm, O3C = 200mm, O2E = 400mm, O2D = 200mm and BD = 150mm. The crank O1A rotates at a uniform speed of 100 rad/s.

[14m]

Find velocity of point “E” of the bell crank lever by; i. IC method.

ii. Relative velocity method.

Q 3. (b) Prove that Hart’s mechanism can trace an exact straight line. [6m]

Q 4. (a) A cam with a minimum radius of 25mm, rotating clockwise at a uniform speed 100 rpm, to give roller follower at the end of a valve rod, motion described below;

i. To raise the valve through 50mm during 120° rotation of cam. ii. To keep the valve fully raised through next 30°.

iii. To lower the valve during the next 60°. iv. To keep the valve closed during rest of the revolution.

Rise of the follower is as per cycloidal motion while fall is as per SHM. Draw displacement, velocity and acceleration diagrams of the follower for one complete revolution of cam. [12m]

Q 4. (b) With a neat sketch; derive an equation for the Path of Contact, Arc of Contact and Contact ratio for the

two gears in mesh. [8m]

Q 5. (a) A 3kg uniform rod rotates in a vertical plane about B. The spring of constant k = 300 N/m and un-stretched length of 120mm is attached to the rod. For the position shown, the angular speed of the rod is 4 rad/s (clockwise). Determine the angular velocity of the rod after it has rotated through 90°.

[10m]

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Q 5. (b) Two gear wheels mesh externally and are to give a velocity ratio of 3:1. The teeth are of involute form, module 6mm, addendum is of one module, pressure angle 20°. The pinion rotates at 90rpm. Determine:

i. No. of teeth on the pinion to avoid interference and the corresponding no. of teeth on the wheel. ii. Length of Path and Arc of contact.

iii. No. of pairs of teeth in contact. iv. Maximum velocity of sliding.

[10m]

Q 6. (a) The driving crank AB of a quick return mechanism as shown in the figure revolves at a uniform speed of 200 rpm; Find the velocity and acceleration of tool box “R”, in the position shown, when the crank makes an angle of 60° with the vertical line of centres PA.

[15m]

What is the acceleration of sliding of the block “B” along the slotted lever PQ. Also find the angular acceleration of link PQ.

Q 6. (b) Explain Chordal action in case of chain drives. [5m]

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Note:

On an average basis; the questions that will be asked in KOM paper would have around 85% of Numerical and Derivation based questions and 15% Theory / Shortnote based questions. Questions will be combination of both.

It is advisable to the students of Revised syllabus; not to keep any chapter as an option. Depending on few chapters only to clear the paper would be too risky in KOM. It may happen that negligible questions

would be asked from those topics.

All the Best for your Subject Preparation

Regular Batch of K.O.M by Irfan sir starts from 13th Jan’18 at Dadar

Documents

Fluid Mechanics: Dec’17 - irfansir.in · Fluid Mechanics: Dec’17 Sem ... What is Kutzbach’s criterion for degree of freedom of plane mechanism? In what ways it differs from