Parked and Operating Loads Analysis in the Aerodynamic Design of Multi-megawatt-scale Floating Vertical Axis Wind Turbines

A good understanding of aerodynamic loading is essential in the design of vertical axis wind turbines (VAWTs) to properly capture design loads and to estimate the power production. This paper presents a comprehensive aerodynamic design study for a 5 MW Darrieus offshore VAWT in the context of multi-megawatt floating VAWTs. This study systematically analyzes the effect of different, important design variables including the number of blades (N), aspect ratio (AR) and blade tapering in a comprehensive loads analysis of both the parked and operating aerodynamic loads including turbine power performance analysis. Number of blades (N) is studied for 2- and 3-bladed turbines, aspect ratio is defined as ratio of rotor height (H) and rotor diameter (D) and studied for values from 0.5 to 1.5, and blade tapering is applied by means of adding solidity to the blades towards blade root ends, which affects aerodynamic and structural performance. Analyses were carried out using a three-dimensional vortex model named CACTUS (Code for Axial and Crossflow TUrbine Simulation) to evaluate both instantaneous azimuthal parameters as well as integral parameters, such as loads (thrust force, lateral force, and torque loading) and power. Parked loading is a major concern for VAWTs, thus this work presents a broad evaluation of parked loads for the design variables noted above. This study also illustrates that during the operation of a turbine, lateral loads are on par with thrust loads, which will significantly affect the structural sizing of rotor and platform & mooring components.

Development of Iceberg Profiling Technology

Iceberg management on the Grand Banks of Newfoundland, Canada is currently carried out without knowledge of the underwater shape of the iceberg. An iceberg profiling system is being developed to integrate the rapid generation of 3D iceberg shape data with a collection of tools that utilize the data to provide recommendations, intended to improve iceberg management effectiveness. The intent is for the system to be operated by vessel crew with minimal training. The system utilizes a LiDAR and a pole mounted multibeam sonar to profile the iceberg sail and keel, respectively. A vessel equipped with the profiling system circles an iceberg twice to collect a profile, a process that on average requires approximately 15–30 minutes. The data is collected in the form of a point cloud, which must be de-noised and corrected for both drift and rotation of the iceberg. Tools have been developed to assess the stability of the iceberg, and to consider the shape of the iceberg relative to towing net dimensions, to provide guidance to the operator regarding the recommended towing direction to avoid iceberg rolling or net slippage events. Other applications of the profile data include an impact loads analysis tool that determines the distribution of potential iceberg loads in the event of a collision with a given platform, and an operational iceberg drift model that uses the iceberg shape to improve iceberg drift forecasts. Large-scale field programs were carried out in both 2018 and 2019 as part of the development process for the system. Data collected has shown that iceberg characteristics have changed significantly when compared to iceberg profile data collected in the 1980s. For a given iceberg waterline length, the more recent data shows significantly reduced drafts. The 1980s iceberg dataset currently dominates the data used as the basis for assessing iceberg loads on surface facilities and iceberg risk to subsea assets. Reduced iceberg drafts will result in reduced risk to subsea facilities and pipelines. These results and observations demonstrate the usefulness of the iceberg profiling system as an environmental monitoring tool, and the data collected has design and operational applications. The development and capabilities of the system are presented, as well as the comparison of the 1980’s and newer iceberg datasets and implications for iceberg risk to facilities on the Grand Banks and surrounding regions.

ANALISIS BEBAN GEMPA TERHADAP KEKUATAN STRUKTUR BANGUNAN MULTI DEGRRE OF FREEDOME

S t r u c t u r al a n aly sis is pla n n e d p h a s e s o f a b uildin g , e s p e cially t h e hig h b uildin g s . I n t h e a n aly sis o f t h e s t r u c t u r e r e q uir e d t o f a cilit a t e t h e m o d elin g c alc ula tio n s r e fle c t a c t u al c o n ditio n s in t h e field , b o t h in s t r u c t u r e a n d in t h e lo a d e d . B e c a u s e alm o s t all p a r t s o f I n d o n e sia , in clu din g t h e e a r t h q u a k e - pro ne areas is a challenge for civil engineering planning in order to design earthquake resistant buildings. Indonesia has many experienced tremendous earthquake W ritin g t his p r o p o s al is in t e n d e d t o b e a ble t o k n o w t h e s t r e n g t h a n d structure of the response S trength multi degree of freedome, on soft ground, located in Tangerang when worn earthquake lateral loads, analysis is done with the help of the SAP program in 2000 ver.15, to get the style - the style such as: the base shear force, lateral force level, ro lling moment and lateral deviation. D y n a mic a n aly sis w a s c o n d u c t e d u sin g t h e r e s p o n s e s p e c t r u m a n aly sis , mass modeling performed with a lump mass models, the sum of the response variance is reviewed with some combinations, such as: CQC, SRSs and ABSSUM.