Experimental investigation of wave run-up and air-gap responses

This paper describes the experimental application of adaptive control to Hybrid Squeeze Film Damper (HSFD) supported rotors. The HSFD has been shown to be an adaptive damper capable of providing infinite damper configurations between short and long damper configurations. Previously, theoretical investigations of the adaptive control of HSFD concentrated on the development of the model reference adaptive control (MRAC) method, as well as development of a nonlinear reference model. Simulations of the performance of the adaptive controller during run-up and coast-down indicated the superior performance of the adaptive controller. In this paper, the adaptive controller is tested on a multi-mode rotor. A test rig is designed and developed using computer control. A simple reference model is investigated consisting of a second order system. Three forms for adaptation gain are studied. The results of the experimental investigation illustrated the performance capabilities of the adaptive controller applied to the HSFD, and moreover indicated the possibility of simple design for the adaptive controller.

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Experimental Study on the Effects of Mooring System on Air Gap Response of Semi-Submersible Platform

Volume 6B: Ocean Engineering ◽

10.1115/omae2020-18814 ◽

2020 ◽

Author(s):

Xu Li ◽

Longfei Xiao ◽

Handi Wei ◽

Mingyue Liu

Keyword(s):

Model Tests ◽

Air Gap ◽

Mooring System ◽

Complex Task ◽

Ocean Engineering ◽

Free Surface Elevation ◽

Mooring Lines ◽

Scaled Model ◽

Air Gap Responses ◽

Floating Platforms

Abstract The air gap response is crucial for the safe design and operation of large-volume floating platforms such as semi-submersible and tension leg platforms. It is a complex task to perform numerical simulation on the air gap response considering the wave free surface elevation and the motions of the floating vessel. Therefore, the prediction of air gap response still relies heavily on model tests. This paper attempts to investigate the effects of the mooring system, especially the effects of the length of mooring lines, on the air gap response of semi-submersible platform based on model tests results. The scaled model of the semi-submersible platform is supported by a symmetric mooring system composed of 8 mooring lines. A set of model tests with different length of mooring lines was performed in the State Key Laboratory of Ocean Engineering basin at Shanghai Jiao Tong University, and the air gap responses of 15 locations were measured using wave probes. The results indicate that the mooring system plays an important role in the air gap response of semi-submersible platform.

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Numerical Study of Air Gap Response and Wave Impact Load on a Moored Semi-Submersible Platform in Predetermined Irregular Wave Train

29th International Conference on Ocean, Offshore and Arctic Engineering: Volume 6 ◽

10.1115/omae2010-20260 ◽

2010 ◽

Author(s):

Xiufeng Liang ◽

Jianmin Yang ◽

Longfei Xiao ◽

Xin Li ◽

Jun Li

Keyword(s):

Impact Load ◽

Numerical Study ◽

Wave Train ◽

Air Gap ◽

Navier Stokes ◽

Design Stage ◽

Wave Impact ◽

Irregular Wave ◽

Run Up ◽

Steep Waves

The importance of understanding air gap response and potential deck impact is well-known in the design stage of semi-submersible platform. The highly non-linear nature of wave elevation around large structures in steep waves makes it difficult to accurately predict wave field under the deck and wave run up along the columns. Present engineering tools for the prediction of air gap response generally based on simplified models. Even the models accounting for nonlinear wave diffraction is not free of uncertainties. A method adopted here couples a Navier-Stokes solver, VOF technique capturing violent free surface and DNV/Seasam predicting motions of moored semi-submersible platform. Air gap response at different locations of the hull was evaluated in predetermined irregular wave train. Wave run up was also measured by wave probes near the columns. Load cells were mounted under the deck of the platform to trace potential deck impact. The predetermined irregular wave train was simulated in a numerical wave tank and verified against physical tank results. Analysis of the air gap response, wave run up and impact loads on the semi-submersible platform were conducted.

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Theoretical and Experimental Investigation of Flex-PCB Air-Gap Windings in Slotless BLDC Machines

IEEE Transactions on Industry Applications ◽

10.1109/tia.2014.2301862 ◽

2014 ◽

Vol 50 (5) ◽

pp. 3153-3160 ◽

Cited By ~ 11

Author(s):

Bruno Dehez ◽

Francois Baudart ◽

Miroslav Markovic ◽

Yves Perriard

Keyword(s):

Experimental Investigation ◽

Air Gap

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Development of Partial Discharge Signal in Ester Oil Impregnated Paper

International Journal of Innovative Technology and Exploring Engineering - Special Issue ◽

10.35940/ijitee.d1898.029420 ◽

2020 ◽

Vol 9 (4) ◽

pp. 2516-2522

Keyword(s):

Experimental Investigation ◽

Power Transformer ◽

Partial Discharge ◽

Statistical Parameter ◽

Dielectric Materials ◽

Mineral Oil ◽

Air Gap ◽

Electrode Configuration ◽

Discharge Activity

Power transformer is the most exorbitant and controversially the most essential equipment. Insulation abortion in transformer can cause stretched term interruption to supply and loss of revenue and the important maintenance procedure. The power transformer consists of organic insulation like Mineral oil, pressboard and paper. In impecunious of bio- degradability and availability, ester oil is replaced by Mineral oil. The partial discharge is a tool for evaluate the insulation atrophy of dielectric materials. In this paper the results of a laboratory based experimental investigation of partial discharge activity in oil – impregnated paper. To guesstimate the statistical parameter for different electrode configuration like different configuration under open air gap condition.

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Nonlinear Amplifications in the Air Gap Response of a Deep Draft Semi-Submersible

Volume 1: Offshore Technology ◽

10.1115/omae2020-18415 ◽

2020 ◽

Author(s):

Anke Song ◽

Yuanlang Cai ◽

Xiaolong Yang

Keyword(s):

Low Frequency ◽

Air Gap ◽

Wave Condition ◽

Amplification Factors ◽

Highly Nonlinear ◽

Wave Basin ◽

Nonlinear Amplification ◽

Diffracted Waves ◽

Air Gap Responses ◽

Incident Waves

Abstract This paper addresses the nonlinear amplifications in the upwelling crests of air gap responses from the wave basin model test of a deep draft semi-submersible in extreme wave condition. Contributions from nonlinear incident waves, vessel motions and wave-body interactions are analyzed separately. Results from the analyses suggest that, nonlinear amplification factors are larger than predictions from second order corrected model for incident and diffracted waves. Low frequency roll and pitch motions will induce larger nonlinear negative vertical motions for points in down-wave area, thus worsen air gap performance. Upwellings are highly related to diffracted wave elevations. Local run-ups due to highly nonlinear wave-body interactions around column walls could result in the nonlinear amplification factors in this area to be up to 230%.

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Linearity and nonlinearity in wave run-up and air-gap response for a semi-submersible platform under irregular wave excitation

Applied Ocean Research ◽

10.1016/j.apor.2020.102218 ◽

2020 ◽

Vol 104 ◽

pp. 102218

Author(s):

Wenyue Lu ◽

Wenhua Zhao ◽

P.H. Taylor ◽

Jianmin Yang ◽

Longfei Xiao ◽

...

Keyword(s):

Air Gap ◽

Wave Excitation ◽

Irregular Wave ◽

Run Up

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Experimental Investigation of Adaptive Control Applied to HSFD Supported Rotors

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1287264 ◽

2000 ◽

Vol 122 (4) ◽

pp. 685-692 ◽

Cited By ~ 12

Author(s):

A. El-Shafei ◽

M. El-Hakim

Keyword(s):

Experimental Investigation ◽

Adaptive Control ◽

Reference Model ◽

Computer Control ◽

Adaptive Controller ◽

Superior Performance ◽

Order System ◽

Squeeze Film ◽

Run Up ◽

Model Reference Adaptive

This paper describes the experimental application of adaptive control to Hybrid Squeeze Film Damper (HSFD) supported rotors. The HSFD has been shown to be an adaptive damper capable of providing infinite damper configurations between short and long damper configurations. Previously, theoretical investigations of the adaptive control of HSFD concentrated on the development of the model reference adaptive control (MRAC) method, as well as development of a nonlinear reference model. Simulations of the performance of the adaptive controller during run-up and coast-down indicated the superior performance of the adaptive controller. In this paper, the adaptive controller is tested on a multi-mode rotor. A test rig is designed and developed using computer control. A simple reference model is investigated consisting of a second order system. Three forms for adaptation gain are studied. The results of the experimental investigation illustrated the performance capabilities of the adaptive controller applied to the HSFD, and moreover indicated the possibility of simple design for the adaptive controller. [S0742-4795(00)01603-3]

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Experimental Investigation of Thermoelectric Power Generation Using Radiative Heat Exchange

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1025-1026.1125 ◽

2014 ◽

Vol 1025-1026 ◽

pp. 1125-1133

Author(s):

Niran Watcharodom ◽

Withaya Puangsombut ◽

Joseph Khedari ◽

Narong Vatcharasatien ◽

Jongjit Hirunlabh

Keyword(s):

Power Generation ◽

Experimental Investigation ◽

Heat Exchange ◽

Waste Heat Recovery ◽

Radiative Heat ◽

Waste Heat ◽

Electrical Power ◽

Air Gap ◽

Radiative Heat Exchange ◽

Thermoelectric Modules

This paper reports experimental investigation of a new concept of waste heat recovery for Thermoelectric Power Generation using Radiative heat exchange principle (TERX). To this end a small scale experimental setup was considered; it was composed of a heated plate, an absorber plate, thermoelectric modules and water cooled heat sink. The dimensions of absorber and heated plates were 0.2 m width and 0.3 m length. The air gap space between the two plates could be adjusted. Ten thermoelectric modules were connected in series parallel (5x2). Tests were made for different air gap spaces and fixed water flow rate (2L/min). A constant electric current (200W) was supplied to the heater of hot plate. Data collected included temperature at various positions and the electrical power generated. Experimental investigation confirmed that using radiative heat exchange principle could be considered for TE waste heat power generation. Increasing air gap decreased the electrical power generated as less radiative heat is absorbed by the thermoelectric modules. Under test conditions, the maximum measured electrical power is 0.3132 W at 0.5 cm of air gap, the corresponding temperature difference between the hot and cool sides of thermoelectric modules was about 35oC. Due to its simplicity of installation as no there is no need for direct contact between the thermoelectric generation set and the source of heat, the proposed concept offers a new alternative for waste heat recovery.

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