Radial Distribution of Solids Concentration in Downer

Abstract

Two different radial solids concentration distributions in downer have been reported, i.e. the ˄ shape combining with reverse-core-annulus and the core-annulus structures. The occurrence of these two patterns has not been quantitatively interpreted. In this paper, the aerodynamic theory is used in two-phase flow analysis. A transverse force on the particles, i.e. the Kutta-Joukowski transverse force, is introduced to explain and quantify the formations of these two radial solids concentration distributions in downer. This force is the function of the particle velocity gradient, the slip velocity and the gas density. Based on the available experimental data proposed in the published literatures, the distribution of the Kutta-Joukowski transverse force in downer is discussed. The results show that this force is the main factor for these two profiles occurrence.

Research on Special Stability of Scientific Research Equipment on Oceanographic Research Vessels

“…In principle, vessel navigation speed should not be greater than flow velocity, but in practice, it is difficult to ensure that the former is lower than the latter. According to the Rules and Technical Guidelines for Discharge Measurement by ADCP published by the Office of Surface Water (OSW) of the United States Geological Survey (USGS), the analysis of ADCP error sources [6,7], and relevant statistical data, when the ratio of navigation speed to flow velocity is controlled at 1.3 -2.5, the accuracy of discharge measurement by ADCP can be little influenced. When the ratio of navigation speed to flow velocity exceeds 3, the influence on the measurement accuracy of ADCP will gradually increase.…”