LIQUID LAYER CHARACTERISTICS IN STRATIFIED ATOMIZATION FLOW

Measurements of liquid film thickness, liquid-to-wall shear stress, pr essure drop and visual observations have been carried out in a 50.8 mm i.d. horizontal pipe flow loop. Attention was paid to the lateral var iation of the liquid properties by making measurements at location THE TA = 0-degree (pipe bottom) and THETA = 45-degrees Statistical analysi s of liquid film records led to the determination of local mean thickn ess, RMS values as well as of other wave characteristics (wave amplitu de, intermittency, etc.) useful in computing gas-liquid interface fric tion. These data were complemented by similar statistical information from the shear stress measurements. The gas-liquid interface was found to deviate significantly from the usually assumed flat profile. A new result obtained here is that a small film thickness is associated wit h reduced local shear stress; i.e. that a lateral mean shear stress va riation exists in this flow regime. In general, larger intensities of wall stress fluctuations are measured in thin films; e.g. at THETA = 4 5-degrees as compared to THETA = 0-degree (thicker film).Power spectra of film thickness and of shear stress display similarities indicative of the effect of waves on wall stress. There is also evidence suggest ing that damping of interfacial waves takes place in relatively thick films. Probability densities of local layer thickness and of wall stre ss exhibit striking similarities indicative of a substrate on which a moving wavy layer develops. Using the above new data, improved estimat es of the interfacial friction factor f(i) are obtained. The data exhi bit a linear dependence of f(i) on the liquid layer Reynolds number, a s in previous studies. An expression relating an equivalent interface roughness to wave characteristics is also presented.