DOI: 10.1615/TSFP6
VORTICAL FLOW FEATURES IN A HEMISPHERICAL CAVITY ON A FLAT PLATE
要約
This paper presents the results of numerical and experimental researches of generation of flow oscillations which are caused by interaction of the hydrodynamic and hydroacoustic phenomena inside a three-dimensional spherical cavity. The results of numerical and physical simulation of vortex movement features are shown inside a dimple and in its near wake. The symmetric and asymmetric large-scale vortical systems inside a cavity are find out depending on the flow regime, and location and periodicity of their break up are shown. The evolution of tornado-like vortices subjected to a switch mechanism that results in appearance of infra low-frequency modulating transversal oscillations of vortex motion inside the dimple. Discrete peaks are find out in spectral dependencies of pressure and velocity fluctuations. These local rises of the velocity and pressure fluctuation levels correspond to rotating frequency of the vortex systems inside the cavity, their breakup frequency, wake mode frequency of oscillations of cavity vortical movement, caused by a hydrodynamic resonance, and also self-sustained shear layer frequency of oscillations inside the dimple, which corresponded to a hydroacoustic resonance. The form and sizes of the quasi-stable largescale vortex structures, the region of their origin and stages of development are submitted. Instantaneous and averaged characteristics of wall pressure fluctuations of vortical movement inside the cavity and in its near wake differ from each other, from nonlinear interaction of vortical structures with each other and streamlined surface.