Publications
The aero-hydrodynamic interference impact on the NREL 5-MW floating wind turbine experiencing surge motion
Mar 1, 2024Journal Ocean Engineering
Publisher Elsevier
DOI https://doi.org/10.1016/j.oceaneng.2024.116970
Volume 295
The present work seeks to explore how the surge response of a semi-submersible platform affects the aerodynamic performance and wake properties of a 5-MW Floating Offshore Wind Turbine (FOWT) when subjected to fully coupled wind-wave load conditions. In order to attain a more comprehensive understanding of the impact of platform surge displacement, a comparative analysis of the aerodynamic performance and wake characteristics was conducted. This analysis involved comparing a floating turbine experiencing surge motion with a conventional floating turbine operating under stable fixed-platform conditions. This simulation employs an overset mesh technique to accurately capture the impact of the semi-submersible platform's surge response on both the aerodynamic behavior and wake properties. Furthermore, the integration of Dynamic Fluid Body Interaction (DFBI) and Volume of Fluid (VOF) approaches is utilized to precisely understand the aero-hydrodynamic interaction and simulate the water-air interface surface. A thorough analysis was conducted to assess aerodynamic performance, catenary analysis, and hydrodynamic reactions by comparing the results obtained from CFD simulations with those acquired from the FAST and OrcaFlex codes. The CFD findings indicate a significant impact of the platform surge response on the apparent wind velocity perpendicular to the rotor plane, which arises from the combined effects of the incoming wind velocity and surge-induced velocity. Moreover, the velocity recovery of the wake flow downstream of the rotor is faster during surge motion than that of the fixed-bottom turbine. The importance of this finding is especially relevant in wind farm scenarios marked by diminished aerodynamic interference between adjacent turbines. Furthermore, CFD investigations and visualizations are carried out on shedding vortices in the wake, tower-blade tip interference, and tension force of the mooring lines. These aspects cannot be adequately captured using potential codes. Graphical abstract
Couette-Poiseuille flow over a backward-facing step: Investigating hydrothermal performance and irreversibility analysis
Jan 1, 2024Journal Case Studies in Thermal Engineering
Publisher Elsevier
DOI https://doi.org/10.1016/j.csite.2023.103954
Volume 53
The present study investigates the hydrothermal performance of Couette-Poiseuille flow over a backward-facing step. With a focus on the irreversibility analyses, the study sheds light on the flow behavior and explores the impact of key parameters, including Reynolds number, and wall terminal velocities. The study investigates a range of laminar Reynolds numbers between 100 and 800, as well as wall terminal velocities, Ut between −3 and 3. Notably, the results reveal a unique flow structure appears at negative Ut, where multiple separation zones (bounces) form downstream of the step. The number of bounces depends on both Re and Ut. An enhancement in the Nusselt number can be observed as the value of -Ut increases, which can be directly correlated to the increase in the number of bounces and the decrease in the reattachment length. On the contrary, the increase in the +Ut results in a decrease in heat transfer, driven by the increase in the reattachment length. The thermal performance factor, TPF shows an improvement for Re of 200 and 400 at Ut of −0.5, while TPF worsens as the value of -Ut increases due to the pressure drop induced by separation bubbles. Thermal entropy generation was identified as the main source of irreversibility processes for all cases
Experimental Study and 3D Optimization of Small-Scale Solar-Powered Radial Turbine Using 3D Printing Technology
Aug 9, 2023Journal machines
Publisher MDPI
DOI https://doi.org/10.3390/machines11080817
Small-Scale Turbines (SSTs) are among the most important energy-extraction-enabling technologies in domestic power production systems. However, owing to centrifugal forces, the high rotating speed of SSTs causes excessive strains in the aerofoil portions of the turbine blades. In this paper, a structural performance analysis is provided by combining Finite Element Methods (FEM) with Computational Fluid Dynamics (CFD). The primary objective was to examine the mechanical stresses of a Small-Scale Radial Turbine (SSRT) constructed utilizing 3D printing technology and a novel plastic material, RGD 525, to construct a SSRT model experimentally. After introducing a suitable turbine aerodynamics model, the turbine assembly and related loads were translated to a structural model. Subsequently, a structural analysis was conducted under various loading situations to determine the influence of different rotational speed values and blade shapes on the stress distribution and displacement. Maximum von Mises and maximum main stresses are significantly affected by both the rotor rotational speed and the working fluid input temperature, according to the findings of this research. The maximum permitted deformation, on the other hand, was more influenced by rotational speed, while the maximum allowable fatigue life was more influenced by rotating speed and fluid intake temperature. Also, the region of the tip shroud in the rotor had greater deflection values of 21% of the blade tip width. Keywords: small-scale turbine; FEA; 3D printing; stress distribution; RGD 525