کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
655486 | 1457642 | 2013 | 14 صفحه PDF | دانلود رایگان |
To study the three-dimensional interfacial structure development in vertical two-phase flow, air–water upflow experiments were performed in a rectangular duct. Various non-uniform two-phase profiles were created by injecting air from individually controlled spargers at the duct inlet into uniformly injected water flow. A four-sensor conductivity probe was used to measure local void fraction, interfacial area concentration, bubble velocity and Sauter mean diameter at three axial locations to record the development of two-phase parameters. Experimental results showed that the lateral development across the wider dimension of the duct was significant with a non-uniform inlet profile when compared to a uniform inlet profile. It is postulated that lift, wall and turbulent forces are the major contributors to the lateral distribution of the two-phase interfacial structures making this an useful experiment for benchmarking three-dimensional two-fluid models. In examining the interfacial area, the shearing-off of group 1 bubbles (defined as the smaller spherical and distorted bubbles) from the skirt region of group 2 bubbles (defined as the bigger cap and churn bubbles), the coalescence of group 2 bubbles due to wake entrainment, and random collision are the major source and sink mechanisms of interfacial area concentration.
► Lateral flow development is significant with a non-uniform inlet profile.
► The major interfacial area sources for group 1 bubbles are shearing-off.
► Wake entrainment and random collision are major group 2 IAC sources.
► Lateral transport of group 1 bubbles is driven by turbulent dispersion.
► Significant lateral forces exist which push group 2 bubbles to the duct center.
Journal: International Journal of Heat and Fluid Flow - Volume 39, February 2013, Pages 173–186