An Experimental and Theoretical £ Investigation of Annular Steam ...

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3.1..j. ~ > . Tabular Test Sections 10 and 20. The tubular
test section 20, with an inner diameter of 20 mm, is shown in
fig. 3.5.
The siK-1ion area is made in the same manner as in the annular
test section. Both the upper and the lower power clamps are
movable for the whole length of the tube. The wall is provided
with holes for needle contact probes and tubes for pressure-drop
measurements.
The tubular test section 10 is constructed in the same way
as test section 20.
3.1.4. Power Supplies
The electrical power to the test sections and steam generator
is delivered from two 250 kW thyristor-controlled dc power
supplies and one 165 kW vario transformer.
The dc power supplies are ASEA type YNVD, giving 100 V,
2500 A each. Because of severe problems with electric noise in
the measuring channels, it was necessary to install two filterinductances
to reduce the superimposed ac-components from these
supplies. (Cf. Cortzen (1976)). Each of the filters has an inductance
of 150 ull at 250 A and 34 utt at 2500 A.
3.1.5. Pressure-Drop Measurement Equipment
The axial pressure gradient in the test sections was determined
by means of electric differential pressure transducers
(dp-cells), type Rosemount model 1151 DP.
The pressure range is -10 kPa to + 190 kPa with an accuracy
of ± C.5 kPa.
In the annular test sections, there are 8 pressure taps
placed 0.5 m apart. The upper pressure tap is placed immediately
below the outlet, the lowest 3.5 m below. The partial pressure
drops between the taps and the total pressure drop were measured
by means of 8 dp-cells.
In the tubular test sections, the pressure taps located from
the outlet and down to 1.0 m below are placec 0.25 m apart. From
1.0 m to 4.0 m below, the distance between the taps is 0.5 m.
Thus, in the tubular test section, 1 total and 10 partial pressure
drops were measured.