Particle Concentration Measurement and Flow Regime Identification in Multiphase Pipe Flow Using a Generalised Dual-frequency Inversion Method

An acoustic particle concentration measurement method, originally developed for marine sediment, in which the backscattered energy received by emitter-receiver transducers in the megahertz range is used to construct concentration profiles in suspensions of solid particles in a carrier fluid is applied to suspensions of general engineering interest. Four particle species with range of densities and sizes are used. Concentration profiles in horizontal, turbulent pipe flow at a Reynolds number of 50,000 and three nominal volume fractions are presented for each particle species, using experimentally determined acoustic coefficients, in order to isolate the influence of particle size and density on transport and settling in solid-liquid multiphase flows. It is clear from the results that the method allows the degree of segregation in real suspensions and slurries to be measured, and has a range of potential applications in the nuclear and minerals processing industries, for example. Lastly, the limiting conditions of the method are explored through the concept of an acoustic penetration depth.