HEAT&MASS TRANSF. (LL) W/CONNECT<CUSTOM>
6th Edition
ISBN: 9781266141652
Author: CENGEL
Publisher: MCG
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Find : 1. dynamic load on each bearing due to the out-of-balance couple; and 2. kinetic energy of
the complete assembly.
[Ans. 6.12 kg: 8.7 N-m]
L
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3.
4.
5.
1.
2.
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DO YOU KNOW?
Why is balancing of rotating parts necessary for high speed engines?
Explain clearly the terms "static balancing' and 'dynamic balancing'. State the necessary conditions
to achieve them.
Discuss how a single revolving mass is balanced by two masses revolving in different planes.
Chapter 21: Balancing of Rotating Masses .857
Explain the method of balancing of different masses revolving in the same plane.
How the different masses rotating in different planes are balanced?
OBJECTIVE TYPE QUESTIONS
The balancing of rotating and reciprocating parts of an engine is necessary when it runs at
(a) slow speed
(b) medium speed (c) high speed
A disturbing mass, attached to a rotating shaft may be balanced by a single mass m, attached in
the same plane of rotation as that of my such that
(a)
(b) F
For static…
Provide a real-world usage example of the following:
Straightness
Circularity
Parallelism
What specific tools, jigs, and other devices are used to control the examples you provided?
856 Theory of Machines
5.
A shaft carries five masses A, B, C, D and E which revolve at the same radius in planes which are
equidistant from one another. The magnitude of the masses in planes A, C and D are 50 kg, 40 kg
and 80 kg respectively. The angle between A and C is 90° and that between C and D is 135°
Determine the magnitude of the masses in planes B and E and their positions to put the shaft in
complete rotating balance.
[Ans. 12 kg, 15 kg; 130° and 24° from mass A in anticlockwise direction]
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- 4. The distributed load in Figure 4 varies linearly from 3wo per unit length at A to wo per unit length at B and the beam is built in at A. Find expressions for the shear force V and the bending moment M as functions of x. 3W0 Wo A L Figure 4 2 Barrow_forward1. The beam AB in Figure 1 is subjected to a uniformly distributed load wo = 100 N/m. Find the axial force N, the shear force V and the bending moment M at the point D which is midway between A and B and illustrate their directions on a sketch of the segment DB. wo per unit length A D' B all dimensions in metersarrow_forward5. Find the shear force V and the bending moment M for the beam of Figure 5 as functions of the distance x from A. Hence find the location and magnitude of the maximum bending moment. w(x) = wox L x L Figure 5 Barrow_forward
- Dry atmospheric air enters an adiabatic compressor at a 20°C, 1 atm and a mass flow rate of 0.3kg/s. The air is compressed to 1 MPa. The exhaust temperature of the air is 70 degrees hottercompared to the exhaust of an isentropic compression.Determine,a. The exhaust temperature of the air (°C)b. The volumetric flow rate (L/s) at the inlet and exhaust of the compressorc. The power required to accomplish the compression (kW)d. The isentropic efficiency of the compressore. An accounting of the exergy entering the compressor (complete Table P3.9) assuming that thedead state is the same as State 1 (dry atmospheric air)f. The exergetic efficiency of the compressorarrow_forwardA heat pump is operating between a low temperature reservoir of 270 K and a high temperaturereservoir of 340 K. The heat pump receives heat at 255 K from the low temperature reservoir andrejects heat at 355 K to the high temperature reservoir. The heating coefficient of performance ofthe heat pump is 3.2. The heat transfer rate from the low temperature reservoir is 30 kW. The deadstate temperature is 270 K. Determine,a. Power input to the heat pump (kW)b. Heat transfer rate to the high-temperature reservoir (kW)c. Exergy destruction rate associated with the low temperature heat transfer (kW)d. Exergy destruction rate of the heat pump (kW)e. Exergy destruction rate associated with the high temperature heat transfer (kW)f. Exergetic efficiency of the heat pump itselfarrow_forwardRefrigerant 134a (Table B6, p514 of textbook) enters a tube in the evaporator of a refrigerationsystem at 132.73 kPa and a quality of 0.15 at a velocity of 0.5 m/s. The R134a exits the tube as asaturated vapor at −21°C. The tube has an inside diameter of 3.88 cm. Determine the following,a. The pressure drop of the R134a as it flows through the tube (kPa)b. The volumetric flow rate at the inlet of the tube (L/s)c. The mass flow rate of the refrigerant through the tube (g/s)d. The volumetric flow rate at the exit of the tube (L/s)e. The velocity of the refrigerant at the exit of the tube (m/s)f. The heat transfer rate to the refrigerant (kW) as it flows through the tubearrow_forward
- Water enters the rigid, covered tank shown in Figure P3.2 with a volumetric flow rate of 0.32L/s. The water line has an inside diameter of 6.3 cm. The air vent on the tank has an inside diameterof 4.5 cm. The water is at a temperature of 30°C and the air in the tank is at atmospheric pressure(1 atm) and 30°C. Determine the air velocity leaving the vent at the instant shown in the figurearrow_forwardUsing method of sections, determine the force in member BC, HC, and HG. State if these members are in tension or compression. 2 kN A 5 kN 4 kN 4 kN 3 kN H B C D E 3 m F 2 m -5 m 5 m- G 5 m 5 m-arrow_forwardDetermine the normal stresses σn and σt and the shear stress τnt at this point if they act on the rotated stress element shownarrow_forward
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