S. R

Bio: S. R is an academic researcher. The author has co-authored 4 publications.

Analysis of Spar with Floating Dock

Abstract: The installation of wind turbines at offshores is a complex and arduous task. The floating dock concept is the current method for installing an offshore wind turbine which is discussed in details in this paper. This paper investigates a floating dock that provides shielding to the spar foundation while installing a 5 MW wind turbine at the offshore site. The floating dock of 60 m inner diameter and 85 m length is analyzed using ANSYS AQWA software for calculating the Heave Response Amplitude Operator (RAO). Viscous damping is provided as an external damping matrix in the hydrodynamic diffraction analysis of ANSYS AQWA. It is noticed that viscous damping plays a major role in the analysis. The behavior of Spar with and without dock is analyzed. It can be observed that the floating dock helps in reducing the heave RAO of the Spar.

Rock Type And Berthing Velocity Of 80000t Vessel On Design Of Berthing Structure

Abstract: A berthing structure is a port and harbour structure to which the vessel is securely berthed and moored. The design of berthing structures depends on various factors such as vessel characteristics, embedded soil/rock, the berthing velocity which depends on site and berthing conditions. The behaviour of the berthing structure for different grades of embedded rocks and different berthing velocities is studied through numerical analysis using STAAD PRO. In order to carry out conceptual design the embedment length of pile is to be assumed. The fixity depth and embedment length for piles in rock is assumed based on the requirements of long flexible piles as per IS 2911 Part 1/Sec2. The berthing force for different berthing velocity corresponding to site and berthing condition as per IS 4651 code and analysis of pile supported berthing structure for five grades of weathered rocks are carried out. For each type of rock, as the berthing velocity increases, the increment in diameter of the pile is more compared to the increment in the length of the pile. For each berthing velocity, as quality of rock increases, decrement in the embedded length of pile is more compared to decrement in diameter which leads to decreased slenderness ratio of pile and less lateral deflection of pile. The design charts are also developed for fixity depth, embedment depth, percentage of steel, diameter of pile etc satisfying the crack width limit for berthing structure with four rows of pile considering all possible load combination.

Computational hydrodynamics of an offshore intake well with curtain wall

Abstract: The wave-structure interaction of an offshore intake well with a curtain wall is computationally investigated with regular waves. The simulation is done using ANSYS-FLUENT, Computational Fluid Dynamics (CFD) tool. The computational domain is governed by continuity and the Reynolds Averaged Navier-Stokes (RANS) equations and modeled in a Cartesian grid system. The combination of structured and unstructured mesh is used to discretize the simulation domain. The numerical model is developed based on the pressure-based transient solver, and the Volume of Fluid (VOF) technique is selected to trace the free surface elevation. The simulations are performed using the 1:20 scale model by varying wave period (T) and wave steepness (H/L). The run-up on the seaward face and pressure on both sides of the curtain wall are measured. The numerical run-up shows good agreement with the experiments for the d/L range of 0.15 to 0.36. The pressure on both sides decreases with increased d/L values and follows the same trend as experiments.

FOTOAN: A Novel Deepwater Anchoring System

Abstract: The lack of energy resources in shallow water depths made deepwater energy resources exploration as an important step. Deepwater energy devices like floating offshore wind turbines (FOWT), hybrid and integrated energy systems, and mobile offshore drilling units often need anchoring support, which is adaptable to all marine conditions. There are several marine anchor types like drag anchors, suction anchors and self-installing anchors, in which dynamically embedded anchors are popular due to the simple installation procedure. In the taut-leg or vertical mooring systems, these dynamically embedded anchor's performance is unsatisfactory. Also, their excess pore pressure dissipation time after installation in NC clay is higher, which made them lesser attractive. Despite its simplicity, this anchoring concept has not gained widespread acceptance for the above-mentioned reasons. Hence, the present work described the novel anchoring concept of foldable torpedo anchor (FOTOAN) and their working mechanism, theoretical capacity estimation and installation sequence in detail. A limited comparative laboratory study of the FOTOAN to the traditional torpedo anchor in soft clay shows the FOTOAN to be more efficient. In the vertical mooring systems, the performance is improved by 3.5 – 5 times. Thus, the FOTOAN has been promised as an efficient technique for deepwater anchoring applications. Also, the installation sequence of FOTOAN with the aid of two anchor handling vessels (AHV-1 & AHV-2) are presented as an example case study.