The Experts below are selected from a list of 6105 Experts worldwide ranked by ideXlab platform

Segere M.l.a. - One of the best experts on this subject based on the ideXlab platform.

  • Vibration-induced settlement of a Slip-Joint connection for offshore wind turbines
    2018
    Co-Authors: Segere M.l.a.
    Abstract:

    The majority of existing offshore wind turbines typically consist of a monopile foundation, a transition piece with a vertically positioned grouted connection, a turbine tower, and a turbine. Of the 2,653 offshore turbines that were installed by the end of 2015, 80 percent are supported by a monopile.Despite the current overwhelming dominance of the monopile, its future application is rather uncertain. Offshore wind turbines have continuously increased in size and have moved to deeper waters; these developments require larger and heavier support structures. It is unlikely that floating structures will be preferred to bottom-founded structures, up to a water depth of 80 m. The question thus becomes whether jackets or monopiles will be used under such conditions? The monopile seems to be losing in this competition, as, to meet the requirements a monopile would have to be extremely large; thus, it may no longer fall within industry limits, both in terms of manufacturing demands and the lifting capacity of dedicated installation vessels. One may wonder whether a single monopile would be necessary, or if a set of intelligently connected smaller length monopiles could suffice. The key to the success of such a concept could be the so-called Slip-Joint connection.A Slip-Joint consists of two conical sections made of steel. This connection does not require any grout and, besides being a connection option for the transition piece and monopile, allows monopiles to be comprised of a number of lighter sections of very large diameters. By employing a Slip-Joint, the applicability of the monopile could be extended to deeper waters and to turbines that have very large rotors and power capacities.Although the Slip-Joint connection has been successfully used for onshore wind turbines in the past, it has not yet been used offshore. One of the challenges in using the Slip-Joint is ensuring a proper fit of the cones despite the imperfections that result from manufacturing tolerances, deformations by pile driving, and the potential damage that may occur during the handling of the cones.In this thesis, it is proposed that a slight difference in the cone angles be used to address the aforementioned imperfections. A steeper cone angle for the transition piece when compared to that of the monopile is proposed. These slightly different cone angles require the upper cone to deform elastically in order to slide down the lower cone during installation. To facilitate the installation process, it is proposed that vibrations be employed in order to cause the upper cone to slide down under its own weight. In order to use this new method of connecting Joints, it will be necessary to investigate the manner in which vibrations influence the relative motions of the two cones that need to achieve stable contact.The objective of this thesis is to investigate the potential of the use of vibrations in the installation and dismounting of a Slip-Joint with slightly different cone angles. The research is conducted by means of numerical modelling and experiments

  • Vibration-induced settlement of a Slip-Joint connection for offshore wind turbines
    2018
    Co-Authors: Segere M.l.a.
    Abstract:

    The majority of existing offshore wind turbines typically consist of a monopile foundation, a transition piece with a vertically positioned grouted connection, a turbine tower, and a turbine. Of the 2,653 offshore turbines that were installed by the end of 2015, 80 percent are supported by a monopile.Despite the current overwhelming dominance of the monopile, its future application is rather uncertain. Offshore wind turbines have continuously increased in size and have moved to deeper waters; these developments require larger and heavier support structures. It is unlikely that floating structures will be preferred to bottom-founded structures, up to a water depth of 80 m. The question thus becomes whether jackets or monopiles will be used under such conditions? The monopile seems to be losing in this competition, as, to meet the requirements a monopile would have to be extremely large; thus, it may no longer fall within industry limits, both in terms of manufacturing demands and the lifting capacity of dedicated installation vessels. One may wonder whether a single monopile would be necessary, or if a set of intelligently connected smaller length monopiles could suffice. The key to the success of such a concept could be the so-called Slip-Joint connection.A Slip-Joint consists of two conical sections made of steel. This connection does not require any grout and, besides being a connection option for the transition piece and monopile, allows monopiles to be comprised of a number of lighter sections of very large diameters. By employing a Slip-Joint, the applicability of the monopile could be extended to deeper waters and to turbines that have very large rotors and power capacities.Although the Slip-Joint connection has been successfully used for onshore wind turbines in the past, it has not yet been used offshore. One of the challenges in using the Slip-Joint is ensuring a proper fit of the cones despite the imperfections that result from manufacturing tolerances, deformations by pile driving, and the potential damage that may occur during the handling of the cones.In this thesis, it is proposed that a slight difference in the cone angles be used to address the aforementioned imperfections. A steeper cone angle for the transition piece when compared to that of the monopile is proposed. These slightly different cone angles require the upper cone to deform elastically in order to slide down the lower cone during installation. To facilitate the installation process, it is proposed that vibrations be employed in order to cause the upper cone to slide down under its own weight. In order to use this new method of connecting Joints, it will be necessary to investigate the manner in which vibrations influence the relative motions of the two cones that need to achieve stable contact.The objective of this thesis is to investigate the potential of the use of vibrations in the installation and dismounting of a Slip-Joint with slightly different cone angles. The research is conducted by means of numerical modelling and experiments.Offshore Engineerin

Rongyao Wang - One of the best experts on this subject based on the ideXlab platform.

  • envelopes for connected operation of the deepwater drilling riser
    Petroleum Exploration and Development, 2012
    Co-Authors: J U Shaodong, Yuanjiang Chang, X U Liangbin, Guoming Chen, Rongyao Wang
    Abstract:

    Abstract The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and Slip Joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex Joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex Joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex Joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible Joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.

  • Envelopes for connected operation of the deepwater drilling riser
    KeAi Communications Co. Ltd., 2012
    Co-Authors: Yuanjiang Chang, Guoming Chen, Xiuquan Liu, Rongyao Wang
    Abstract:

    The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and Slip Joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex Joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex Joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex Joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible Joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded. Key words: deepwater drilling, riser, drilling envelope, non-drilling envelope, EDS actuation envelop

Tsutomu Kawabe - One of the best experts on this subject based on the ideXlab platform.

  • catheter flow sensor with temperature compensation for tracheal intubation tube system
    Sensors and Actuators A-physical, 2014
    Co-Authors: Mitsuhiro Shikida, Kazuhiro Yoshikawa, Takuya Matsuyama, Yudai Yamazaki, Miyoko Matsushima, Tsutomu Kawabe
    Abstract:

    Abstract A micro-electro-mechanical systems catheter flow sensor was integrated into the tracheal intubation tube system to prevent the insertion of the tube into the esophagus. A temperature sensing mechanism was integrated into the catheter flow sensor to compensate for the temperature change in air during flow-rate measurement, and the sensor was placed on the inside the Slip Joint by using an adapter produced using a molding process. The relationship between the sensor output and flow rate was evaluated, and closely matched sensor outputs for both the forward and backward flows were obtained. The tracheal tube in the modified system was inserted into the air passage of a rabbit, and the air flow passing through the tube was directly measured using the integrated catheter flow sensor in real time. By adding the temperature compensation mechanism, the volumes of the expired- and inspired-air almost matched. We believe that a doctor will easily be able to evaluate whether the tube is inserted into the bronchi or the esophagus when using the modified system.

Yuanjiang Chang - One of the best experts on this subject based on the ideXlab platform.

  • envelopes for connected operation of the deepwater drilling riser
    Petroleum Exploration and Development, 2012
    Co-Authors: J U Shaodong, Yuanjiang Chang, X U Liangbin, Guoming Chen, Rongyao Wang
    Abstract:

    Abstract The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and Slip Joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex Joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex Joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex Joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible Joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded.

  • Envelopes for connected operation of the deepwater drilling riser
    KeAi Communications Co. Ltd., 2012
    Co-Authors: Yuanjiang Chang, Guoming Chen, Xiuquan Liu, Rongyao Wang
    Abstract:

    The common critical criterion and nonlinear search method were adopted for the study of connected operation envelopes of deepwater drilling riser and a riser-wellhead-conductor integral finite element model was established. The combination parameters of drilling platform offset, current speed and Slip Joint stroke were used to determine the riser operability envelopes. The results show that the drilling envelope has an upconing shape and is limited by lower flex Joint angle when the surface current speed is low (less than 1.0 m/s). In downstream direction, when the current speed increases, the rotation angle of the lower flex Joint increases and the allowable maximum offset of the platform reduces, but in upstream direction, the conditions will be opposite. When surface current speed exceeds 1.0 m/s, the drilling envelope is limited by upper flex Joint angle. When it is in upstream direction, the increase of current flow will increase the rotor angle of the upper flexible Joint and reduce the drilling envelope rapidly. The non-drilling envelope and emergency disconnect sequence (EDS) actuation envelope are mainly subject to the maximal equivalent stress of the conductor and they will drift towards the upstream direction with the increase of current speed. In addition, through the analysis on influence factors of connection window operation of riser, the tensile force at the top could be increased and drilling fluid density could be reduced properly, so that the drilling envelope could be expanded. Key words: deepwater drilling, riser, drilling envelope, non-drilling envelope, EDS actuation envelop

M L A Segeren - One of the best experts on this subject based on the ideXlab platform.

  • vibration assisted installation and decommissioning of a Slip Joint
    Engineering Structures, 2020
    Co-Authors: Alessandro Cabboi, M L A Segeren, Hayo Hendrikse, A V Metrikine
    Abstract:

    Abstract The structural failure of grouted connections for offshore wind turbines focused the industrial attention towards different and innovative solutions to guarantee a safe connection between the monopile foundation and the turbine tower. An alternative option to the traditional grouted Joint is a direct steel-to-steel connection, also called a Slip-Joint which was sporadically used for onshore wind turbines. To such regard, a proof of concept is illustrated concerning a new installation and decommissioning technique of a Slip-Joint. The key aspect of the proposed method is to guarantee a proper fit and sound contact of the Slip-Joint by means of vibration-assisted settlements. Therefore, the effectiveness of applying a harmonic excitation during the installation and decommissioning procedure is experimentally investigated using a 1:10 scaled model of the Slip-Joint. During the dynamic tests, the applied static load and the settlements of the Joint are monitored using load cells, displacement sensors and strain gauges placed both inside and outside the conical surfaces. For the installation tests, the results show that settlement occurs when applying a harmonic load at specific forcing frequencies. All the vibration-induced settlements tend to stabilize in time, indicating that a sound contact through vibration-assisted installation can be achieved. In a similar way, the decommissioning proved to be effective at certain forcing frequencies. According to all the tests performed during this experimental campaign, both the installation and decommissioning tests showed to be more sensitive to the forcing frequency rather than to the dynamic forcing amplitude.

  • investigation of a Slip Joint connection between the monopile and tower of an offshore wind turbine poster
    EWEA 2013: Europe's Premier Wind Energy Event Vienna Austria 4-7 Febraury 2013, 2013
    Co-Authors: M L A Segeren, E Lourens
    Abstract:

    To circumvent current industry problems related to the settling of grouted connections, a steel-to-steel or Slip Joint connection is proposed for fitting a transition piece onto an installed monopile foundation. In the first part of this contribution, a simplified dynamic analysis of the installation of such a Joint is considered. Assuming velocity dependent Coulomb friction, Slip-stick equations of motion are derived for a simplified 1-D model of the Joint, and the Slip distance under self weight and resulting overlap lengths are calculated for different initial cone angles and friction coefficients. It is concluded that even for small initial cone angles, small angle differences between the top and bottom cone, and low friction coefficients, the tangential displacement caused by the self weight is insufficient to reach the desired contact overlap. In the second part of this contribution, the static capacities (axial and bending) of the Joint in the in-place situation are determined by means of a FE model. Contact analyses are performed based on the ideal situation in which the two parts of the Joint is initially in full contact. Of the parameters varied in these analyses, small cone angles and large overlaps are identified as most conducive to a succesfull transferral of the loads from the transition piece to the monopile. Given the uncertainty on the friction coefficient, it is then also recommended to use a cone angle of 1? and preferably an overlap > 1.5D.