| Interfacial waves created by turbulent gas shear have a pronounced influence on the pressure drop and transport rates of multiphase flow systems. This investigation concentrated on two issues that provide an understanding of the fundamental wave mechanisms which determine the distribution of waves and their subsequent effect on the properties of two-phase flow. First, a theoretical spectral equation, which predicts the character of the gas-liquid interface, is derived based on a dynamic energy balance applied over a frequency spectrum and compared to measured values. Secondly, the origin of roll waves was examined with experimental and theoretical methods.; The experiments were conducted in an 8.5m x 30.5cm x 2.54cm horizontal Plexiglas{dollar}sp{lcub}circler{rcub}{dollar} flow channel with the gas Reynolds (R{dollar}sb{lcub}rm G{rcub}{dollar}) number varied between 4000 and 30000 and the liquid Reynolds (R{dollar}sb{lcub}rm L{rcub}{dollar}) number ranging from 30 to 2000. A parallel wire conductance probe technique was employed to acquire wave surface tracings which are subsequently Fourier transformed into frequency spectra.; The development of the spectral equation, which quantitatively reconstructs the interface, involves a spectral energy balance consisting of three competing fundamental phenomena which are wave growth, wave energy dissipation and nonlinear wave interactions. Functions are derived for these processes and their existence supported with experimental spectral data depicting wave growth and interactions. The resulting theoretical spectra compare favorably with experimental frequency spectra.; The origin of roll waves on thick films (R{dollar}sb{lcub}rm L{rcub}{dollar} greater than 200) is experimentally proven to be an unstable long wavelength disturbance present at gas Reynolds numbers well below the R{dollar}sb{lcub}rm G{rcub}{dollar} at which roll waves initially appear. Linear stability theory was applied to the integral forms of the mass and momentum conservation equations and the resulting neutral stability solution coincided with the onset of these long wavelength waves and not the visual roll wave transition as in earlier studies. The origin of thin film (R{dollar}sb{lcub}rm G{rcub}{dollar} less than 200) roll waves was not clear, but the frequency spectra distinctly showed that this mechanism of formation is different from the thick film case and may be associated with a transition from periodic to solitary behavior of the dominant waves. |
