1 O ltThe Last Chaptergt Measuring Fluid Flow Rate Fluid Velocity Bernoulli equa tion takes the form of where V is the fluid velocity P is the fluid pressure z is the elevation of the location in ID: 233667
Download Presentation The PPT/PDF document "CHAPTER" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
CHAPTER
1
O
<The Last Chapter>
Measuring Fluid Flow Rate,
Fluid Velocity,Slide2
Bernoulli
equation takes the form of
where
V
is the fluid velocity, P is the fluid pressure, z is the elevation of the location in
the pipe relative to a specified reference elevation (datum),
ρ
is the fluid density, and g is gravitySlide3
The velocities at two axial locations in the duct with different
areas are related through the conservation of mass equation,Slide4
where, A is the duct cross-sectional area and
is the fluid mass flow rate (e.g., kg/s).
For an incompressible fluid, the density is constant.
is usually written
in the form:
Equations can be combined
to obtain an expressionSlide5
T
he
theoretical
basis for a class of flow meters in which the flow rate
is determined from the pressure change caused by variation in the area of a conduit.Slide6Slide7
is used to account for nonide
al
effects.
and a parameter
called the Reynolds number,
which is defined asSlide8
When
z
1
=
z
2
Flow Rate Equation becomes as follows:
Slide9
The Reynolds number is
a
dimensionless parameter,Slide10
The
venturi
,
thus operating
within
the range of data in Table
10.1.Slide11Slide12Slide13Slide14
Coriolis
Mass Flowmeter
The Coriolis force is a force that occurs when dynamicproblems are analyzed within a rotating reference frame. Useful flowmeters
based on
this effect are now widely used in the process industries. Consider a fluid flowing
through the U-shaped tube shown in Figure 10.13(a).The tube is cantilevered out from
a rigidly supported base. An electromechanical driver is used to vibrate the free end of
the tube at its natural frequency in the y direction. The amplitude of this vibration will
be largest at the end of the cantilever and zero at the base. Consider an instant in time
when the tube is moving in the -y direction. The fluid moving through the tube away
from the base will not only have a component of velocity in the x direction but also in
the -y direction, and the magnitude of this y component will increase with distancefrom the
base.As a fluid particle moves along the tube, it is thus accelerating in the -ydirection. This acceleration is caused by a Coriolis force in the -y direction applied by
the tube wall. The resultant reaction on the tube wall is a force, F in the *y direction.For the fluid returning to the base, the y component of fluid velocity is decreasing inthe flow direction. This results in a Coriolis
force on the tube wall in the -y direction.Coriolis Mass Flowmeter The Coriolis force is a force that occurs when dynamic problems
are analyzed within a rotating reference frame. Useful flowmeters based on this effect are now widely used in the process industries. Consider a fluid flowing through the U-shaped tube shown in Figure 10.13(a).The tube is cantilevered out from a rigidly supported base. An
electromechanical driver is used to vibrate the free end of the tube at its natural frequency in the y direction. The amplitude of this vibration will be largest at the end of the cantilever and zero at the base. Consider an instant in time when the tube is moving in the -y direction. The fluid moving through the tube away from the base will not only have a component of velocity in the x direction but also in the -y direction, and the magnitude of this y component will increase with distance from the base
. As
a fluid particle moves along the tube, it is thus accelerating in the -y
direction. This acceleration is caused by a
Coriolis
force in the -y direction applied
by the
tube wall. The resultant reaction on the tube wall is a force, F in the *y
direction. For
the fluid returning to the base, the y component of fluid velocity is decreasing
in the
flow direction. This results in a
Coriolis
force on the tube wall in the -y direction.