The increasing depletion of energy resources demands innovative transportation solutions. While conventional pipelines have long addressed environmental and energy challenges, alternative designs, like helical pipelines, offer improved efficiency due to their compact structure, large surface area, and superior mixing capabilities. This study explores the hydrodynamics of rigid spherical and cylindrical capsule transport through helical pipelines, with a focus on analysing velocity, pressure drop, and friction coefficient. The research aims to optimize pipeline design for improved industrial applications by examining local and global flow characteristics. A helical flow loop was built to experimentally validate the boundary conditions applied in the numerical model. The computational domain was discretized using an unstructured mesh approach to ensure flexibility and compatibility with the dynamic mesh technique. The capsules exhibited six-degree-of-freedom (6DOF) motion in a three-dimensional space governed by a user-defined function (UDF) under unsteady turbulent flow through the helical pipeline. The governing equations were solved using the k-ε turbulence model and Reynolds-averaged Navier-Stokes (RANS) equations. This investigation employs both quantitative and qualitative approaches to examine the impact of capsule size, density, flow velocity, pipeline diameter, and the number of helical turns on capsule transport dynamics. The findings pertaining to flow behavior, pressure drop, and capsule velocity suggest that the movement within helical pipes is significantly governed by factors such as specific gravity, capsule dimensions, average flow velocity, and curvature ratio. The velocity of capsules in helical pipelines exceeds that in straight horizontal pipelines by 55%. Capsules characterized by high density undergo the most pronounced inlet pressure drop, progressing toward the outer wall with irregular oscillatory movements, whereas capsules with uniform density exhibit variable pressure drops and transition between the central and inner walls. Capsules with low density demonstrate diminished initial pressure drops but exhibit heightened instability. Variables such as buoyancy effects, secondary flow dynamics, and centrifugal forces play a crucial role in these observed discrepancies. An increase in capsule concentration results in augmented pressure drops while concurrently enhancing flow stability by reducing fluctuations. The experimental results showed a strong correlation with computational fluid dynamics (CFD) predictions, with a deviation of less than 10%. A novel prediction model was developed for spherical and cylindrical capsules to estimate the solid-liquid mixture friction coefficient and capsule velocity ratio. An optimization study was also conducted to minimize total costs, providing a practical framework for pipeline design and industrial applications.
| Date of Award | 18 Aug 2025 |
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| Original language | English |
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| Supervisor | Rakesh Mishra (Main Supervisor) & Naeem Mian (Co-Supervisor) |
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