Effects of 90 deg. vertical elbows on two-phase flow parameters
- Department of Mechanical and Nuclear Engineering, The Pennsylvania State University, 230 Reber Building, University Park, PA 16802, (United States)
This study investigates two-phase flow from vertical-upward to horizontal and horizontal to vertical-downward direction through 90 deg. vertical elbows. Specifically, effects of 90 deg. vertical elbows on two-phase pressure drop, development of bubble distribution, and one-dimensional transport of bubble velocity are studied. Pressure measurements are obtained along the test section over a wide range of flow conditions. The two-phase pressure drops across the elbows are modeled using the modified Lockhart-Martinelli correlation which accounts for the minor loss effect. It is demonstrated that the modified Lockhart-Martinelli correlation can predict the pressure loss across elbows with different orientations and angles by varying the minor loss coefficient. A database is established by measuring two-phase flow parameters across 90 deg. vertical elbows using a four-sensor conductivity probe. It is found that immediately downstream of the 90 deg. vertical-upward elbow, the bubbles have a bimodal distribution along the horizontal radius of the pipe cross-section causing a dual-peak in the profiles of local void fraction and interfacial area concentration. As the flow develops, the bimodal bubble distribution dissipates and develops to a single-peaked bubble distribution near the top of the pipe. Immediately downstream of the 90 deg. vertical-downward elbow, a bimodal bubble distribution is also observed near the inner curvature of the elbow. As the flow develops, the bimodal bubble distribution migrates to the pipe center and finally develops to a characteristic center-peaked bubble distribution. For the area averaged void-weighted bubble velocity, it varies significantly in the elbow regions due to the changes in local velocity profile and bubble distribution caused by the elbow effects. (authors)
- Research Organization:
- American Nuclear Society - ANS, Thermal Hydraulics Division, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 22977503
- Resource Relation:
- Conference: ATH 16: International Topical Meeting on Advances in Thermal Hydraulics, New Orleans, LA (United States), 12-16 Jun 2016; Other Information: Country of input: France; 13 refs.; available on CD Rom from American Nuclear Society - ANS, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- Country of Publication:
- United States
- Language:
- English
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