Measurements in merging flow

Abstract

Previous measurements of the velocity field in the vicinity of two intersecting submerged turbulent jets provided evidence that, contrary to the usual assumptions, intersecting flows may not necessarily be combined using vector addition of velocities or momentum flux densities. To gather additional experimental evidence on the details of the velocity field near the intersection of two submerged turbulent jets, this study measured time average velocity magnitudes and directions of two perpendicular intersecting axisymmetric submerged turbulent incompressible air jets of approximately equal strength. Because of the need to detect reverse flows, a three-dimensional pitot-type probe was used. This could sense yaw and pitch angles as well as velocity magnitudes. Two sets of measurements were taken. The more detailed set was confined to the plane of the nozzles, the less detailed set obtained cross-sectional data at four stations, three of these being in the observed reverse flow. The data show that the reverse flow spreads much more rapidly perpendicular to the nozzle plane than in the nozzle plane, whereas the forward flow is fairly symmetric. , Similarity profiles were found in both the forward and reverse flows. In the forward flow the distribution was essentially Gaussian. This was also true in the backward flow in the direction normal to the plane of the nozzles. In the plane of the nozzles the backward flow profiles were close to semi-elliptical or semi-circular, depending on the scales for plotting.U.S. Department of the InteriorU.S. Geological SurveyOpe