Krish Thiagarajan - Academia.edu (original) (raw)

Uploads

Papers by Krish Thiagarajan

Journal of Marine Science and Technology

Journal of Offshore Mechanics and Arctic Engineering

The aim of this paper is to establish a simple approach to experimentally study the mooring line ... more The aim of this paper is to establish a simple approach to experimentally study the mooring line damping in shallow water, where snap loading may occur more frequently. Experimental measurements were conducted in a wave basin at a scale of 1:50, which corresponds to a full scale of 28 m water depth. A chain made by stainless steel was used, and the tension force at the fairlead was measured by tension gages. Moreover, the line geometry, touchdown point speed, and mooring line velocity were derived from image processing techniques. Surge motions at fairlead were driven from a programmable wavemaker. Regular surge motions with different frequencies and pretensions were tested in this system in order to investigate the quasi-static and dynamic behaviors of the mooring chain. In the quasi-static test, the mooring line keeps a typical catenary shape, and its indicator diagram exhibits a smooth-closed curve. In the dynamic test, the mooring line is fully lifted from the seabed, and it cyc...

Journal of Thermal Science and Engineering Applications

A thermodynamic analysis of the two-phase physics involving a liquid–vapor combination has been s... more A thermodynamic analysis of the two-phase physics involving a liquid–vapor combination has been studied under the regime of conjugate heat and mass transfer phenomena. An experiment has been designed and performed to estimate the interfacial mass transfer characteristics of a liquid–vapor system by varying the liquid temperature. The experimental setup consists of an instrumented tank partially filled with water and maintained at different temperatures. The evaporation of liquid from the interface and the gaseous condensation has been quantified by calculating the interfacial mass transfer rate for both covered and uncovered tanks. The dependence of interfacial mass transfer rate on the liquid–vapor interfacial temperature, fractional concentration of the evaporating liquid, the surface area of the liquid vapor interface, and the fill level of the liquid has been established through the present experimental study. An estimation of the overall mass transfer rate from the interface du...

ANZIAM Journal

This study outlines the estimation of entropy generation of a stored liquid-vapour combination. A... more This study outlines the estimation of entropy generation of a stored liquid-vapour combination. A salient feature of the present study is the incorporation of a separated flow model for the calculation of entropy generated by a diabatic two phase system. Equations of state corresponding to different thermodynamic equilibria are used for these calculations. Two distinct expressions are proposed for the determination of the total entropy generated by the diabatic saturated two phase system that comprise liquid and ullage regions. The dissipative energy losses in various liquid-ullage systems is quantified through the derived mathematical relations obtained for the overall entropy generated by the system. These developed expressions form the basis of an experimental determination of the entropy generation rate. A parametric study on temperature influencing entropy generation has been performed in the context of different thermal transport mechanisms.

Journal of Offshore Mechanics and Arctic Engineering

Model tests were conducted on three generic floating wind turbine systems in 2011 and reported in... more Model tests were conducted on three generic floating wind turbine systems in 2011 and reported in a series of papers at the 31st Ocean, Offshore, and Arctic Engineering Conference in 2012. These tests were conducted at the MARIN facility in The Netherlands, by a consortium of universities, government research organizations, and industry. As part of the testing program, decay tests in platform pitch were conducted with and without wind forcing. It was found that for spar and semisubmersible type structures, resonant pitch motion was damped due to wind in storm sea conditions. The nonlinear decay motion of a floating wind turbine platform is modeled using a one degree-of-freedom nonlinear oscillation equation about a mean offset angle. Attention is paid to the turbine thrust coefficient and its variability with respect to oncoming flow speed, which in turn is affected by the structure pitch motion. The equation of motion reveals that the mean offset position has an important role in t...

Journal of Offshore Mechanics and Arctic Engineering

Environmental conditions created by winds blowing oblique to the direction of the waves are neces... more Environmental conditions created by winds blowing oblique to the direction of the waves are necessary to conduct some survivability tests of offshore wind turbines. However, some facilities lack the capability to generate quality waves at a wide range of angles. Thus, having a wind generation system that can be rotated makes generating winds that blow oblique to the waves possible during survivability tests. Rotating the wind generation system may disrupt the flow generated by the fans because of the effect of adjacent walls. Closed or semiclosed wind tunnels may eliminate the issue of wall effects, but these types of wind tunnels could be difficult to position within a wave basin. In this work, a prototype wind generation system that can be adapted for offshore wind turbine testing is investigated. The wind generation system presented in this work has a return that minimizes the effect that the walls could potentially have on the fans. This study characterizes the configuration of ...

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 1, Parts A and B, 2004

Model tests were conducted on two 1: 100 scaled models of a typical concrete gravity substructure... more Model tests were conducted on two 1: 100 scaled models of a typical concrete gravity substructure at the University of Western Australia. The two models had dimensions 0.5 m length× 0.5 m width with the first model being a sealed closed bottom box of height 0.1 m and the second model being an open bottom box with skirt length of 0.1 m. The open bottom model had the capacity to hold an air cushion with dimensions 0.49 m width× 0.49 m length× 0.08 m height. Each model was floated at a constant draft of 0.1 m and tested in water ...

Computer Methods in Applied Mechanics and Engineering, Jul 1, 2009

... coupling between the pressure and velocity fields and also helps to impose the incompressibil... more ... coupling between the pressure and velocity fields and also helps to impose the incompressibility of the ... the number of neighboring particles the accuracy of the SPH method can be improved, the computational ... In SPH calculations the particles are moved by integration of (21).

Computational Mechanics, 2011

In this paper, sloshing phenomenon in a rectangular tank under a sway excitation is studied numer... more In this paper, sloshing phenomenon in a rectangular tank under a sway excitation is studied numerically and experimentally. Although considerable advances have occurred in the development of numerical and experimental techniques for studying liquid sloshing, discrepancies exist between these techniques, particularly in predicting time history of impact pressure. The aim of this paper is to study the sloshing phenomenon experimentally and numerically using the Smoothed Particle Hydrodynamics method. The algorithm is enhanced for accurately calculating impact load in sloshing flow. Experiments were conducted on a 1 : 30 scaled two-dimensional tank, undergoing translational motion along its longitudinal axis. Two different sloshing flows corresponding to the ratio of exciting frequency to natural frequency were studied. The numerical and experimental results are compared for both global and local parameters and show very good agreement.

Ships and Offshore Structures, 2016

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 1, Parts A and B, 2005

ABSTRACT

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 1, Parts A and B, 2005

ABSTRACT

Journal of Marine Science and Technology

Journal of Offshore Mechanics and Arctic Engineering

The aim of this paper is to establish a simple approach to experimentally study the mooring line ... more The aim of this paper is to establish a simple approach to experimentally study the mooring line damping in shallow water, where snap loading may occur more frequently. Experimental measurements were conducted in a wave basin at a scale of 1:50, which corresponds to a full scale of 28 m water depth. A chain made by stainless steel was used, and the tension force at the fairlead was measured by tension gages. Moreover, the line geometry, touchdown point speed, and mooring line velocity were derived from image processing techniques. Surge motions at fairlead were driven from a programmable wavemaker. Regular surge motions with different frequencies and pretensions were tested in this system in order to investigate the quasi-static and dynamic behaviors of the mooring chain. In the quasi-static test, the mooring line keeps a typical catenary shape, and its indicator diagram exhibits a smooth-closed curve. In the dynamic test, the mooring line is fully lifted from the seabed, and it cyc...

Journal of Thermal Science and Engineering Applications

A thermodynamic analysis of the two-phase physics involving a liquid–vapor combination has been s... more A thermodynamic analysis of the two-phase physics involving a liquid–vapor combination has been studied under the regime of conjugate heat and mass transfer phenomena. An experiment has been designed and performed to estimate the interfacial mass transfer characteristics of a liquid–vapor system by varying the liquid temperature. The experimental setup consists of an instrumented tank partially filled with water and maintained at different temperatures. The evaporation of liquid from the interface and the gaseous condensation has been quantified by calculating the interfacial mass transfer rate for both covered and uncovered tanks. The dependence of interfacial mass transfer rate on the liquid–vapor interfacial temperature, fractional concentration of the evaporating liquid, the surface area of the liquid vapor interface, and the fill level of the liquid has been established through the present experimental study. An estimation of the overall mass transfer rate from the interface du...

ANZIAM Journal

This study outlines the estimation of entropy generation of a stored liquid-vapour combination. A... more This study outlines the estimation of entropy generation of a stored liquid-vapour combination. A salient feature of the present study is the incorporation of a separated flow model for the calculation of entropy generated by a diabatic two phase system. Equations of state corresponding to different thermodynamic equilibria are used for these calculations. Two distinct expressions are proposed for the determination of the total entropy generated by the diabatic saturated two phase system that comprise liquid and ullage regions. The dissipative energy losses in various liquid-ullage systems is quantified through the derived mathematical relations obtained for the overall entropy generated by the system. These developed expressions form the basis of an experimental determination of the entropy generation rate. A parametric study on temperature influencing entropy generation has been performed in the context of different thermal transport mechanisms.

Journal of Offshore Mechanics and Arctic Engineering

Model tests were conducted on three generic floating wind turbine systems in 2011 and reported in... more Model tests were conducted on three generic floating wind turbine systems in 2011 and reported in a series of papers at the 31st Ocean, Offshore, and Arctic Engineering Conference in 2012. These tests were conducted at the MARIN facility in The Netherlands, by a consortium of universities, government research organizations, and industry. As part of the testing program, decay tests in platform pitch were conducted with and without wind forcing. It was found that for spar and semisubmersible type structures, resonant pitch motion was damped due to wind in storm sea conditions. The nonlinear decay motion of a floating wind turbine platform is modeled using a one degree-of-freedom nonlinear oscillation equation about a mean offset angle. Attention is paid to the turbine thrust coefficient and its variability with respect to oncoming flow speed, which in turn is affected by the structure pitch motion. The equation of motion reveals that the mean offset position has an important role in t...

Journal of Offshore Mechanics and Arctic Engineering

Environmental conditions created by winds blowing oblique to the direction of the waves are neces... more Environmental conditions created by winds blowing oblique to the direction of the waves are necessary to conduct some survivability tests of offshore wind turbines. However, some facilities lack the capability to generate quality waves at a wide range of angles. Thus, having a wind generation system that can be rotated makes generating winds that blow oblique to the waves possible during survivability tests. Rotating the wind generation system may disrupt the flow generated by the fans because of the effect of adjacent walls. Closed or semiclosed wind tunnels may eliminate the issue of wall effects, but these types of wind tunnels could be difficult to position within a wave basin. In this work, a prototype wind generation system that can be adapted for offshore wind turbine testing is investigated. The wind generation system presented in this work has a return that minimizes the effect that the walls could potentially have on the fans. This study characterizes the configuration of ...

23rd International Conference on Offshore Mechanics and Arctic Engineering, Volume 1, Parts A and B, 2004

Model tests were conducted on two 1: 100 scaled models of a typical concrete gravity substructure... more Model tests were conducted on two 1: 100 scaled models of a typical concrete gravity substructure at the University of Western Australia. The two models had dimensions 0.5 m length× 0.5 m width with the first model being a sealed closed bottom box of height 0.1 m and the second model being an open bottom box with skirt length of 0.1 m. The open bottom model had the capacity to hold an air cushion with dimensions 0.49 m width× 0.49 m length× 0.08 m height. Each model was floated at a constant draft of 0.1 m and tested in water ...

Computer Methods in Applied Mechanics and Engineering, Jul 1, 2009

... coupling between the pressure and velocity fields and also helps to impose the incompressibil... more ... coupling between the pressure and velocity fields and also helps to impose the incompressibility of the ... the number of neighboring particles the accuracy of the SPH method can be improved, the computational ... In SPH calculations the particles are moved by integration of (21).

Computational Mechanics, 2011

In this paper, sloshing phenomenon in a rectangular tank under a sway excitation is studied numer... more In this paper, sloshing phenomenon in a rectangular tank under a sway excitation is studied numerically and experimentally. Although considerable advances have occurred in the development of numerical and experimental techniques for studying liquid sloshing, discrepancies exist between these techniques, particularly in predicting time history of impact pressure. The aim of this paper is to study the sloshing phenomenon experimentally and numerically using the Smoothed Particle Hydrodynamics method. The algorithm is enhanced for accurately calculating impact load in sloshing flow. Experiments were conducted on a 1 : 30 scaled two-dimensional tank, undergoing translational motion along its longitudinal axis. Two different sloshing flows corresponding to the ratio of exciting frequency to natural frequency were studied. The numerical and experimental results are compared for both global and local parameters and show very good agreement.

Ships and Offshore Structures, 2016

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 1, Parts A and B, 2005

ABSTRACT

24th International Conference on Offshore Mechanics and Arctic Engineering: Volume 1, Parts A and B, 2005

ABSTRACT