Analysis of the Trafficability of Spherical Internal Detectors in Pipelines

Yue Cui, Hui-Qing Lan, Nan Lin, Ke-Xin Tan, Zhao-Qi Jiang, Xiang-Bin Yang

DOI: https://doi.org/10.64486/m.65.1.10
Online publication date: October 13, 2025

Abstract: This study aims to enhance the motion stability of a spherical internal de-tector within a flow field, thereby preventing jamming or deviations during the in-spection process. Firstly, a fluid-structure interaction model of a spherical detector in a pipeline was built, and flow field calculations were performed for a straight pipe and a 60° elbow with a 600 mm diameter, examining various ball-to-pipe diameter ratios. The analysis, including the flow field and pressure distribution characteris-tics of the spherical internal detector within the pipe configurations, was supple-mented by experimental verification. The findings reveal that the thrust generated by the spherical internal detector correlates positively with the ball-to-pipe diameter ra-tio. However, an excessively high ratio 0.8 led to a rapid decrease in fluid velocity in the wake region and an increase in the radial region. Significantly, when the spher-ical internal detector navigates through a 60° pipe elbow, its angular velocity triples compared to that in a straight pipe section, potentially reducing the detector’s ser-vice life. For 600 mm diameter pipes, it is recommended that the optimal condition is achieved with a ball-to-pipe diameter ratio of 0.6 and an initial fluid flow velocity of 1.5 m/s to extend service life while ensuring optimal trafficability of the spherical internal detector.

Keywords: spherical internal detector; fluid-structure interaction; trafficability; flow velocity; angular velocity

This article is published online first and will appear in Metalurgija, Vol. 65, Issue 1 (2026).