Pregunta 1
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[blank_start]Fluids[blank_end] are substances that do not permanently resist distortion and, hence, will change their shape.
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[blank_start]Incompressible[blank_end] fluids are those that are inappreciably affected by changes in pressure, e.g. most liquids.
Pregunta 3
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[blank_start]Compressible[blank_end] fluids are those that are appreciably affected by changes in pressure, e.g. most gases.
Pregunta 4
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[blank_start]Fluid statics[blank_end] is the branch of momentum transfer concerned with fluids at rest.
Pregunta 5
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[blank_start]Fluid dynamics[blank_end] is the branch of momentum transfer concerned with fluids in motion.
Pregunta 6
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[blank_start]Newton’s Law of Viscosity[blank_end] roughly states that there is a linear relation between shear stress and rate of shear, and that the proportionality constant is the viscosity.
Pregunta 7
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[blank_start]Kinematic viscosity[blank_end] is the ratio of viscosity to density.
Pregunta 8
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[blank_start]Newtonian[blank_end] fluids are those that obey Newton’s Law of Viscosity, i.e. have constant viscosities.
Pregunta 9
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[blank_start]Non-Newtonian[blank_end] fluids are those having viscosities as a function of shear rate.
Pregunta 10
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Gases and low molecular weight liquids are generally [blank_start]Newtonian[blank_end] fluids.
Pregunta 11
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[blank_start]Laminar[blank_end] flow is the type of flow at low velocities where the layers of fluid seem to slide by one another without eddies or swirls being present.
Pregunta 12
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[blank_start]Turbulent[blank_end] flow is the type of flow at higher velocities where eddies are present giving the fluid a fluctuating nature.
Pregunta 13
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The [blank_start]Reynold’s Number[blank_end] is the ratio of the kinetic or inertial forces and viscous forces.
Pregunta 14
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For a straight circular pipe, values less than [blank_start]2100[blank_end] indicates laminar flow, and above [blank_start]4000[blank_end] indicates turbulent flow.
Pregunta 15
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Frictional losses in the entrance region are [blank_start]larger[blank_end] than those of the same length of fully developed flow.
Pregunta 16
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[blank_start]Mach[blank_end] number is the ratio of the fluid velocity to the speed of sound or acoustic velocity.
Pregunta 17
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For Mach number greater than 1, flow is [blank_start]supersonic[blank_end]. If equal to 1, flow is [blank_start]critical or sonic[blank_end] and the velocity equals the local speed of sound. If less than 1, flow is [blank_start]subsonic[blank_end].
Pregunta 18
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The ratio of heat capacities for air is typically [blank_start]1.4[blank_end].
Pregunta 19
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[blank_start]Venturi[blank_end] meters are often used to measure flows in large lines, such as city water systems. For ordinary industrial installations, they are relatively expensive and takes considerable amount of space. The [blank_start]orifice[blank_end] meter overcomes the disadvantages of this meter but in exchange for a much larger head or power loss.
Pregunta 20
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For incompressible fluids, the compressibility factor, Y is essentially equal to [blank_start]1[blank_end].
Pregunta 21
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Generally, the word “[blank_start]pump[blank_end]” designates a machine or device for moving an incompressible fluid.
Pregunta 22
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These are devices for moving gas (usually air).
Respuesta
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Fans
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Blowers
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Compressors
-
Pumps
Pregunta 23
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[blank_start]Fans[blank_end] discharge large volumes of gas at low pressures of the order several hundred mm of water.
Pregunta 24
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[blank_start]Blowers[blank_end] and [blank_start]compressors[blank_end] discharge gases at higher pressures.
Pregunta 25
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In pumps and fans, the pressure of the fluid does not change appreciably, and [blank_start]incompressible[blank_end] flow can be assumed.
Pregunta 26
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If the pressure on the liquid in the suction line drops to the vapor pressure, some of the liquid flashes into vapor. This is called [blank_start]cavitation[blank_end].
Pregunta 27
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The [blank_start]reciprocating[blank_end] and [blank_start]rotary[blank_end] pumps can be used to very high pressures, whereas [blank_start]centrifugal[blank_end] pumps are limited in their head and are used for low pressures.
Respuesta
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reciprocating
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rotary
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centrifugal
Pregunta 28
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In general, in chemical and biological processing plants, [blank_start]centrifugal[blank_end] pumps are primarily used.
Pregunta 29
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The most common method of moving small volumes of gas at low pressures is by means of [blank_start]fans[blank_end].
Pregunta 30
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[blank_start]Incompressible flow[blank_end] theory can be used to calculate the power of fans.
Pregunta 31
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Non-Newtonian fluids can be divided into two broad categories on the basis of their shear stress/shear rate behavior:
• Shear stress is independent on time or duration of shear ([blank_start]time-independent[blank_end])
• Shear stress is dependent on time or duration of shear ([blank_start]time-dependent[blank_end])
Respuesta
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time-independent
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time-dependent
Pregunta 32
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These are the simplest because they differ from Newtonian fluids only in that their linear relationship does not go through the origin.
Examples: peat slurries, margarine, chocolate mixtures, grease, soap, grain-water suspensions, toothpaste, paper pulp, and sewage sludge
Pregunta 33
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The majority of non-Newtonian fluids are in this category.
The apparent viscosity decreases with increasing shear rate.
Examples: polymer solutions, greases, starch suspensions, mayonnaise, biological fluids, detergent slurries, and paints.
Pregunta 34
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These fluids are far less common than pseudoplastics.
The apparent viscosity increases with increasing shear rate.
Examples: corn flour-sugar solutions, wet beach sand, starch in water, potassium silicate in water, and some solutions containing high concentrations of powder in water.
Pregunta 35
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These fluids exhibit a reversible decrease in shear stress with time at a constant rate of shear.
Pregunta 36
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These fluids exhibit a reversible increase in shear stress with time at a constant rate of shear.