Velocity profiling in hydrotransport
CEDA Dredging Days 2017 - Sustainable Dredging - Continued Benefits
van der Spek A.M., Fernald M., Bailey T.
Abstract: An algorithm for the calculation of the rate of ﬂow from a ﬁve sensor velocity proﬁler was developed. The algorithm produces ﬂow rate values that are to within a few percent of available reference ﬂow rate values for polydisperse sand up to the point where a stationary sand bed is laid down. An operational deﬁnition of sanding slurry ﬂows is formulated. Based on this deﬁnition a metric, a ζ value, is developed as the ratio of the absolute value of the velocity gradient (shear rate) near the bottom of the pipe to the absolute value of the velocity gradient (shear rate) near the top of the pipe. This ζ value appears to be a useful early warning quantity in polydisperse sand slurry ﬂow but completely fails to indicate sanding behavior in monodisperse sand slurry ﬂow. Field experience of the ﬁve sensor array velocity proﬁler in a big bore hydro-transport line is presented showing the behavior of the meter under conditions representative of the ﬂow of sand and water mixtures in practical conditions.
Key words: velocity proﬁle, polydisperse, monodisperse, shear rate, stratiﬁcation