Momentum Transfer Flashcards
The viscosity of a gas
increases with increase in temperature
It is a dimensionless number that characterizes the flows of a fluid in a conduit
Reynolds number
Turbulent flow occurs for cases involving
a. viscous fluid
b. very narrow passages for capillary tube
c. very slow motions
d. none of these
D.
The Reynolds number for ideal fluid flow
Infinity
Formula for mass flow rate
volumetric flow rate (Qv) x density
Formula for volumetric flow rate (Qv)
Velocity x Cross Sectional Area of a Pipe
Formula for mass velocity (G)
mass flow rate/area
Momentum Transfer Chapter in Perryās Handbook
Chapter 6
Actual work formula for pumps (positive work displacement)
Work ideal/ efficiency
Actual work formula for turbines (negative work displacement)
Work ideal x efficiency
When a fluid flows through a reducer in a piping system, the velocity at the outlet end is __ the velocity of the inlet.
More than
The connector used for pipes that must be broken at intervals for maintenance
Union
Which valve is used accurately to regulate the flow of fluids and gases at low flow rates?
Needle valve
Which of the following is NOT true?
a. A pump will operate safely if its NPSH is greater than zero.
b. Fans and blowers are used to transport gases.
c. Pumps and blowers increase the mechanical energy of the fluid.
d. The power loss due to friction in a venturi meter is greater than in an orifice meter.
D.
Which statement is not true?
a. Potential flow is a flow of compressible fluids with no shear.
b. Rotameters are variable-head meters.
c. There are 8 schedule numbers in used for standard pipes.
d. Roughness has no appreciable effect on the friction factor when flow is laminar.
C. (10 schedule numbers are available)
Friction loss formula
FL = (2fLV^2/gcD)
The formula for area of rectangular duct (non-circular conduit)
A= ab/2(a+b)
The formula for the area of annular space (non-circular conduit)
A = pi/4 (D^2-d^2)
The formula for friction loss due to pipe fittings (Ff)
Ff = kfV^2/2gc
The formula for head loss
E = Hg/gc (where H = head loss in length)
Viscous flow is also?
Laminar flow
Equation used for finding f for natural gases?
Weymouth Equation
f = 0.008/D^(1/3)
Formula for viscosity when kinematic viscosity is given
Kinematic viscosity x density
Mach number formula for compressible fluids
V/Vmax
Vmax formula for compressible fluids
Sqrt (RT/MW)
Other formula for Reynolds number
DG/viscosity (where G is mass velocity)
Compression ratio (r) formula
r = nthroot (pressure of last stage compressor/pressure of first stage compressor)
where n is the no. of stages
How do you determine the pressure in between stages of compressors?
Multiply each inlet pressure with the compression ratio
Darcy friction factor (fD) formula
fD = 4f (four times the fanning friction factor)
Formula for delta H in pitot tubes
delta H = Hm ((SGM/SG)-1) (g/gc)
where Hm = manometer reading
SGM = spec. gr. of fluid in manometer
SG = spec. gr. of fluid in pipe
Ratio of V/Vmax for laminar flow
0.5
For the laminar flow of a fluid in a circular pipe of radius R, the Hagen-Poiseuille equation predict the volumetric flowrate to be proportional to
R^4
Pipes having diameter 14 inches or more are designated by their
Outside Diameter
When the flow is laminar
The pressure drop is proportional to the first power of the velocity.
Most commonly used joint in the underground pipe lines is the
Sleeve joint
Schedule number of a pipe, which is a measure of its wall thickness, is given by
1000 Pā/S
Water hammer in a pipeline result from the
rapid pressure change due to a rapid change in the rate of flow.
Molten soap mass is transported by a ____ pump
Gear
Nominal size of the discharge pipe of a pump is usually_____ the nominal size of the inlet pipe.
smaller than
Location of vena-contracta in an orificemeter does not depend upon the
type of orifice
High specific speed of a pump implies that, it is a/an______ pump.
Axial flow
