The cross-correlation flow measurement technique is a promising method
in the two phase flow measurement field. Further research is conducti
ng to utilize this technique in the measurement in paper industry. Emp
hasis is placed on the design of the polarity correlator for flow meas
urement, the accuracy of metering and the analysis of correlator chara
cteristics. The paper presents a state-sequenced polarity structure of
the simple digital correlator with variable length pre-delay based on
a sophisticated microprocessor. The dynamic data tracking feature aut
omatically adjusts clock of the hardware and time constant to compensa
te for rapid fluctuations in flow rate. The variable length pre-delay
expands the flow velocity range to be measured and saves the calculati
on time. Finally the paper also presents the test that the ultrasonic
flowmeter including an ultrasonic double sensor and the correlator ope
rated in a 33.7 mm diameter tube in which pulp suspension was flowing.
The experiment indicates that the cross-correlation velocity is linea
rly proportional to the reference flow velocity measured by magnetic f
lowmeter. All the designed automatic features operated satisfactorily.