Effect of Particle Size and Loading on Development Region in Two-Phase Flows


Abstract: An experimental study was conducted on the development length of a two-phase flow produced by the loading of solid particles by means of a particle feeder into air flowing through a horizontal pipe. Development length was defined as the sufficient distance downstream of the particle feeder in which a homogeneous particle distribution in air sensed with the variation of local friction factors was attained. The static pressure gradients dP/dx were measured along the test pipe to determine the local friction factors to estimate the development length for a variety of air-solid particle suspensions. Crushed wheat and semolina particles of different size, shape and apparent density were used to determine the influence of physical particle characteristics on the extent of development region. The measurements were conducted in air flow Reynolds number range of 51500\leqRe\leq109000 at particle loading ratios of M_p/M_a, 5%\leq M_p/M_a\leq 30%. In the covered ranges of the variables, development length was found to be a strong function of Re such that an increase in Re caused a decrease in the development length while loading ratio seemed to be of secondary importance. Although the particle size by itself was found to be of not much importance for the size range covered in the experiments, for the critical values of Re (103000) and M_p/M_a(5%) particle size was found to be effective on the development length.

Keywords: Two-Phase Flow, Clean Air Flow, Loading Ratio, Development Length, Friction Factor

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