Session: 04-05-02 Subsea Structures & Equipment II

Submission Number: 181693

Configurations' Investigation for a Simultaneous Underwater Cable Laying and Burial Jet Sled (Hydroplow) via CFD 

Simultaneous Lay & Burial (SLB) of subsea power cables is a well-spread installation and protection method in many cases. The SLB Jet Sleds bare jetting nozzles to open-cut the seabed’s soil while being towed forward, with significantly lower tow force required in comparison to traditional subsea ploughs. Such tools are Asso.subsea’s Hydroplow series combining a chamber baring cutting nozzles, with mechanical pulling movement. Jetting nozzles are custom-made, engineered and tailored for Asso.subsea’s project needs, with in-house design, CFD assessment and construction by the company. This tool is investigated in terms of its flow field under operating conditions. The flow field induced post the jetting nozzles is crucial for the effective cutting ability of the tool, especially in cohesive soils such as Clays with higher Undrained Shear Strength (Su/Cu), thus the knowledge of the flow field characteristics is important for assessing many operational parameters and optimizing them.

In the Hydroplow tool investigation presented, eight (8) individual configurations were set for Computational Fluid Dynamics (CFD) assessment with the use of a commercial software (Fluent, Ansys). Configurations are a way to manipulate flow characteristics of the same tool for various types of soil and operational conditions. All configurations are part of a real-scale measurement test carried out on the premises of the company, making each CFD study able to be validated in terms of flow characteristics. Each configuration differentiates tool’s set up in terms of nozzle size (diameter) and “blinded” nozzles’ combination patterns.

All configuration cases were approached as steady-state flow regimes and the flow field values of interest were exported. The critical values investigated were the minimum flow velocity for the cutting nozzles, the mass-flow rate needed in order to build the inlet pressure imposed and -in parallel- the flow velocity in the cleaning nozzles of the Hydroplow. Results were compared with in-situ values from tests carried out by the company for early acceptance of use for the tool where a very good agreement was observed.

At a second level of CFD results’ elaboration, complex phenomena of cavitation were observed in areas of high velocity flow. These areas are of dual interest, since cavitation occurrence is from the one side a drawback for mechanical systems’ life endurance, but from the other side could be beneficial for soil cutting and removal which is the target of tool’s use. An estimation of the relevant operating depth which is the threshold for cavitation’s occurrence is attempted, while a conversation on the benefit or not of cavitation on such tools’ nozzles is long-lasting.

Presenting Author: Gazanfar Sadiq Asso.subsea

Presenting Author Biography: Ghazanfar Sadiq is a Mechanical Design Engineer with a strong background in both mechanical and computer engineering.
He holds a Bachelor’s Degree in Mechanical Engineering from the Technological Institute of Piraeus, followed by a second Bachelor’s Degree in Computer Science from the University of West Attica. He is currently completing his Master’s Degree in Mechanical Engineering at the National Technical University of Athens (NTUA) — the most prestigious engineering university in Greece.
With over nine years of professional experience in design engineering, he began his career at VIOHALCO, one of the largest industrial groups in Greece. During his tenure there, he designed and developed a wide range of heavy industrial machinery for the steel industry — including melting and treatment furnaces, furnace chargers, conveyors, cranes, and piping systems.
Currently, he is part of Asso Subsea's team, a global leader in subsea cable installation and trenching technology. His role involves the design and engineering of subsea trenchers and trenching equipment, integrating both mechanical design and advanced engineering analysis. This position has allowed him to gain significant expertise in Finite Element Analysis (FEA), strengthening his ability to deliver technically sound and innovative engineering solutions.
He integrates creative design principles with analytical engineering methods to deliver efficient and reliable solutions.

Authors:

Gazanfar Sadiq Asso.subsea
Ioannis Sandalis Asso.subsea
Anastasios Kopanidis Asso.subsea