Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Three-dimensional numerical investigation of single- and two-phase flows in blind-tee pipes
Hefu Zhang1, Fenghui Han1, 2*, Yuxiang Liu1, Zhe Wang1 and Wenhua Li1, 22

1 Marine Engineering College, Dalian Maritime University
National Center for International Research of Subsea Engineering Technology and Equipment, Dalian Maritime University
Dalian, Liaoning, ChinaAccording to the open literature, previous studies are mainly focused on
the applications of blind-tee pipes in erosive environments, while theflow mixing physics for multiphase flow measurements have not yet
been thoroughly investigated in details. Chen et al. (2006) investigates
the relative erosion severity between plugged tees and elbows for dilutegas/solid two-phase flow where the pressure is close to the atmosphericpressure. Pouraria et al. (2017) and Duarte et al. (2020) carried out
numerical studies to access the relative erosions in blind tees, andindicated that the erosion rate was significantly affected by the pipe
diameter, flow velocity and mass loading of the fluid. Hjertaker et al.
(2018) characterized the effectiveness of blind tee mixing using a highspeed gamma-ray tomograph. Razali et al. (2021) and Ma et al. (2021)
carried out experimental investigation to study the flow-mixing effect of
the blind tee installed at the test section entrance. Liu et al. (2021) studied
the internal flow characteristics of the jumper tubes with blind tees
installed at different positions. Millington (2016) investigated the mixingconditions of gas-oil two-phase fluid flowing into the blind tee in thecase of vertically downstream installation of venturi pipes. Bluestein(2019) presented an experimental and computational comparison of theturbulent flow field for a sharp 90 degree elbow and plugged tee junction.
Ong et al. (2017) studied some configurations of blind-tees at Re=1000.
Han et al. (2020) investigated the effects of blind-tee length, endstructure shape and flow velocity on the mixing condition inside blindtee pipes. However, none of them provide detailed flow physics insideblind-tee pipes about local two-phase flow parameters.

ABSTRACT
Blind-tee is an important component in offshore piping systems for themultiphase flow mixing and measurements of oil and gas products. In
this paper, a three-dimensional numerical study has been performed on
the single and two-phase flows in the pipelines with blind tees in orderto analyze the mixing conditions. The effects of blind-tee pipes on thegas-liquid bubble flow in different orientations are investigated, anddetailed comparisons are made to reveal the differences between thesingle and two-phase flows in blind tees. It can help to further understandthe multiphase flow physics and mixing conditions in blind-tee pipes.

KEY WORDS: Blind-tee pipe; flow mixing; multiphase flow; threedimensional simulation.
INTRODUCTION
The pipe fittings and joints occur very often in offshore and subsea
piping systems, which are applied to change the flow direction of oil andgas products. The common pipe fittings and joints include elbows(Crawford, et al., 2009; Dutta, et al., 2016), blind tees (Han, et al., 2020),
T-junctions and Y-junctions (Beneš, et al., 2013; Su, et al., 2018), which
would show different flow characteristics with each other (Maurya, et al.,2021). The flow characteristics inside these connections need to bestudied in order to provide theoretical basis for an appropriate flowengineering design.

The objective of the present study is to analyze the mixing conditions ofmultiphase flow characteristics in blind-tee pipes. To this end, a threedimensional computational fluid dynamics study has been performed on
the single and multiphase flows in the pipelines with blind tees inturbulent flow regime. Firstly, the single-phase liquid flow in a typicalblind-tee pipe is simulated to reveal the flow characteristics both insideand downstream the blind-tee section by analyzing the streamlines,
velocity profiles and swirl intensity (Sudo, et al., 1998; Sudo, et al., 2000;
Sudo, et al., 2001). Then, the Eulerian-Eulerian model coupled with themultiple size group model is adopted for the two-phase flow simulations,and the numerical study is carried out on the gas-liquid bubble flow tofigure out the multiphase flow physics inside the blind-tee pipes (Ishiiand Kim, 2004). The effects of blind tees on the gas-liquid flow inAmong various geometric configurations of the connections for theprocess piping systems, blind tees are applied to promote the mixing
condition in the technologies of multiphase flow meters and also widelyused instead of standard elbows in industrial practice. Most multiphaseflow meters on these pipelines require an upstream blind tee to promote
the mixing condition of the incoming gas-liquid flow for an accurate
determination of individual phase fraction and flow rate (Brister, 2013;
Pinguet, et al., 2014). Furthermore, blind tees are widely used instead ofstandard elbows in industrial practice to reduce the corrosion and erosion
caused by particles (Chen, et al., 2006; Zhou, et al., 2022). Thus, theinterest of this study is focused on simulating the flow in blind-tee pipes.

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