EXPERIMENTAL INVESTIGATION OF SPATIAL CONCENTRATION SPECTRA OF A SOLID IN A SLURRY IN HORIZONTAL PIPELINE FLOW

Slurry flow problems confront a broad range of industries, including those involved in power generation, mining, petroleum and gas production, chemical and petrochemical manufacture, metals manufacture, environmental issues, hydrology and fossil energy conversion. The present understanding of two-phase liquid-solid mixtures, and even their simplest fully developed flows in pipes and channels, is not completely satisfactory. Progress in understanding the results of laboratory experiments must take into account the complicated flow pattern phenomena that exist and which are directly associated with spatial and temporal distribution of the component concentration. Any two-phase measurement techniques and instrumentation developments are particularly important, and in this aspect, especially, development of the concentration measurements in liquid-solid two-phase flows is essential in order to develop experimental research. Such a measurement system is related to a description of mixture turbulence and flow pattern, and may be a significant step towards the building of a tool for the quantitative study of the phenomena. This paper presents the experimental data for sand-water flow in a pipe. The goal is to measure in situ concentration with a developed capacitive system; that is, a system of measuring capacitors placed tangential to the mixture flow and on the surface of the channel walls in a non-obstructive manner. The experiments were conducted using the capacitive technique for measurements of spatial concentration, its time fluctuations and its space distribution. The measurement system was developed, built, calibrated, and used successfully in this investigation. Using this system, responding to changes of capacitance with spatial concentration of slurry, time spectra of spatial concentration fluctuations in turbulent slurry flows in horizontal pipe have been measured. This paper demonstrates the applicability of the technique for spatial concentration distribution in time and space measurements as well as the reverse model for correlation between the spatial concentration and its distribution. A fast response, linearized capacitive concentration measurement system has been used to obtain statistical measurements in naturally fluctuating sand-water flow in a horizontal pipe. It is demonstrated that the concentration fluctuation frequency may be used as an objective and quantitative flow pattern discriminator for two-phase flow.