Geology Reference
In-Depth Information
result is simple, following derivations identical to that given in Chapter 8 for
turbine torque, and given by the formula T
mud
= T
air
(U
mud
/U
air
) (Q
mud
/Q
air
)
2
. Self-
spinning “turbosirens” such as that in Figures 9.4c,d, in the leading author's
U.S. Patent 5,831,177, interestingly, do not suffer from static torque problems;
they spin continuously, drawing on the power of the flow in the oncoming flow.
Figure 9.4c,d.
Self-spinning “turbosiren” designed in
wind tunnel and validated in mud flow loop (U.S. Patent 5,831,177).
We next summarize the key procedural steps for siren static torque testing.
These are given to guide engineers new to the test techniques developed thus far
so that all necessary steps are followed.
9.2.2
Siren static torque testing procedure
.
1.
Record the time of day, date, temperature and humidity and describe any
relevant conditions, e.g., exposure to sunshine or cold. The data are used to
determine air density from a suitable physical formula.
2.
Place the siren test fixture in the wind tunnel with the rotor at the
downstream side and remove the electric motor from the siren assembly.
Make sure that the rotor spins freely.
3.
Follow the suggestions of Figure 9.4b. For example, hang a weight W
1
on
the string attached to the circular wire wheel and compute the restoring
torque W
1
R and record the relative angle open between siren stator and
rotor A
1
. Repeat with different weights W
n
which would correspond to
torques T
n
and angles A
n
. Also record the flow rate Q
n
obtained.
4.
Ensure correct torque measurement. Remember that flow rate will change
as the degree of siren closure changes. Rate needs to be monitored
accurately to guarantee reliable predictions for other flow rates.
Periodically increase the flow rate substantially and verify that the
dependence of torque on rate (at the same stator-rotor angle) is quadratic.
5.
What are the highest values of mud weight and mudpump flow rate for this
mud siren in field operations? Denote these by U
mud
and Q
mud
.
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