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Flywheel Question with answer, Study notes of Theory of Machines

Techno India UniversityTheory of Machines

Flywheel question with answer to understand the topic clearly , various type of questions are there to understand

Typology: Study notes

2013/2014

Available from 07/11/2023

rajesh-kumar-80
rajesh-kumar-80 🇮🇳

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1. What is flywheel?
A flywheel is a heavy body rotating about its axis. It acts as a reservoir of energy which is stored in the form of
kinetic energy. The extra energy is stored during the idle stroke of the driven machinery and released during the
working stroke. Thus, flywheel controls the fluctuations of speed during each cycle of the driven machinery.
2. What are the functions of flywheel in a machine?
The primary function of a flywheel is:
a. To absorb energy when demand of energy id less than the supply
b. To give out energy when demand of energy is more than the supply.
3. What types of stresses are set up in the flywheel rims?
a. Tensile stress due to the centrifugal force
b. Tensile bending stress due to restraint of the arms
c. Shrinkage stresses due to the unequal rate of cooling of casting.
4. What are the various types of flywheels?
a. Solid disc type
b. Rimmed type with either arms or solid web
Solid disc type flywheel is rarely used because they have less capacity of storing energy.
Rimmed type flywheels with arms are preferred because they can store more energy. Small rimmed type
flywheels are manufactured with solid web or holes drilled in the web.
5. Why flywheels are used in punching machines?
Use of flywheel in punching machine is due to the following reasons:
a. It decreases the variation of speed during each cycle of punching machine.
b. It decreases the fluctuation of speed due to difference in output and input
c. It stores energy during idle stroke and releases during working stroke.
6. Why flywheel is used in IC engines?
In IC engine or stem engine the energy is developed during the power stroke, no energy is developed during
suction, compression and exhaust strokes in 4 stroke engines. It helps the crank shaft to run at uniform speed by
performing its primary function
7. What is the difference in the function of governor and a flywheel?
Governor regulates the mean speed of an engine when there are variations in load by changing the supply of
working fluid. Flywheel does not maintain a constant speed. It reduces the fluctuations.
8. Coefficient of fluctuation of speed is ———— of maximum fluctuation of speed and the mean speed
Ratio
9. Due to centrifugal forces acting on the rim, the flywheel arms will be subjected to ————- stresses
Tensile
10. Why flywheel arm is usually elliptical?
This shape helps in more section modulus for the dame weight. This results in more strength than circular
section
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1. What is flywheel? A flywheel is a heavy body rotating about its axis. It acts as a reservoir of energy which is stored in the form of kinetic energy. The extra energy is stored during the idle stroke of the driven machinery and released during the working stroke. Thus, flywheel controls the fluctuations of speed during each cycle of the driven machinery. 2. What are the functions of flywheel in a machine? The primary function of a flywheel is: a. To absorb energy when demand of energy id less than the supply b. To give out energy when demand of energy is more than the supply. 3. What types of stresses are set up in the flywheel rims? a. Tensile stress due to the centrifugal force b. Tensile bending stress due to restraint of the arms c. Shrinkage stresses due to the unequal rate of cooling of casting. 4. What are the various types of flywheels? a. Solid disc type b. Rimmed type with either arms or solid web Solid disc type flywheel is rarely used because they have less capacity of storing energy. Rimmed type flywheels with arms are preferred because they can store more energy. Small rimmed type flywheels are manufactured with solid web or holes drilled in the web. 5. Why flywheels are used in punching machines? Use of flywheel in punching machine is due to the following reasons: a. It decreases the variation of speed during each cycle of punching machine. b. It decreases the fluctuation of speed due to difference in output and input c. It stores energy during idle stroke and releases during working stroke. 6. Why flywheel is used in IC engines? In IC engine or stem engine the energy is developed during the power stroke, no energy is developed during suction, compression and exhaust strokes in 4 stroke engines. It helps the crank shaft to run at uniform speed by performing its primary function 7. What is the difference in the function of governor and a flywheel? Governor regulates the mean speed of an engine when there are variations in load by changing the supply of working fluid. Flywheel does not maintain a constant speed. It reduces the fluctuations. 8. Coefficient of fluctuation of speed is ———— of maximum fluctuation of speed and the mean speed Ratio 9. Due to centrifugal forces acting on the rim, the flywheel arms will be subjected to ————- stresses Tensile 10. Why flywheel arm is usually elliptical? This shape helps in more section modulus for the dame weight. This results in more strength than circular section

11. Under what consideration the shaft for a flywheel is designed? It is designed under shear stresses produced due to the combined action of torsion and bending moment. 12. In a flywheel, the major axis of the elliptical section of the arm is the plane of rotation. Write done the reason for this arrangement. The arms may have to carry the full torque load due to high inertia of the flywheel when the energy input to its shaft is cut off. The arm may be assumed as a cantilever fixed at the hub and carrying the load at the rim end. This bending moment lies in the plane of rotation of the flywheel. Therefore, the major axis of the arms must be parallel to the tangential force F acting on the flywheel. Bending moment on the arm, M = F(R-dh/2) F = t/(nR) Where n = number of arms Section modulus of arm, Z = (π/32) b1a

Bending stress σb = M/Z

13. On what basis the material of flywheel is selected? a. High tensile strength b. High fatigue strength c. Low shrinkage 14. What are the advantages of having elliptical section of flywheel arm? The flywheel arms are made of elliptical with major axis twice the minor axis. The major axis lies in the plane of rotation and provides double the resistance against bending moment. 15. Difference between flywheel and governor - A flywheel is used to mitigate cyclic fluctuations in available energy but a governor is used to adjust the supply of fuel as per the load. - The energy stored in the flywheel is kinetic which is 100% available but the governor mechanism involves friction. - The flywheel is not used when cyclic fluctuation of energy is small or negligible. - While a governor is necessary for all the types of engines because it limits the fuel supply as per demand. - If we have constant load then the governor will remain idle but due to cyclic fluctuations in energy available, the flywheel will always work. - Governor has no influence in cyclic fluctuations in energy and flywheel has no influence on the mean speed of an engine. 16. Define the following terms - Coefficient of Fluctuation of Speed, coefficient of steadiness, fluctuation of energy, maximum fluctuation of energy, Coefficient of Fluctuation of Energy - Coefficient of fluctuation of speed: The difference between the maximum and minimum speeds during a cycle is called the maximum fluctuation of speed. The ratio of the maximum fluctuation of speed to the mean speed is called coefficient of fluctuation of speed.

are called fluctuation of energy. The areas BbC, CcD, DdE etc. represent fluctuations of energy. A little consideration will show that the engine has a maximum speed either at q or at s. This is due to the fact that the flywheel absorbs energy while the crank moves from p to q and from r to s. On the other hand, the engine has a minimum speed either at p or at r. The reason is that the flywheel gives out some of its energy when the crank moves from a to p and from q to r. The difference between the maximum and the minimum energies is known as maximum fluctuation of energy Coefficient of Fluctuation of Energy It is defined as the ratio of the maximum fluctuation of energy to the work done per cycle. It is usually denoted by CE.