ORCID Profile
0000-0002-9157-3343
Current Organisation
Australian Maritime College
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Publisher: Elsevier BV
Date: 08-2023
Publisher: Elsevier BV
Date: 11-2019
Publisher: ASME International
Date: 16-03-2021
DOI: 10.1115/1.4050210
Abstract: Roll motion of a planing hull can be easily triggered at high speeds, causing a significant change in hydrodynamic pressure pattern, which can threaten the stability of the vessel. Modeling and investigating roll motion of a planing vessel may require a strong coupling between motions in vertical and transverse planes. In the present paper, we have used a mathematical model to analyze the roll of a planing hull by coupling surge, heave, pitch, and roll motions using 2D + T theory to study the effects of roll-induced vertical motions on roll coefficients and response. Mathematically computed forces and moments as well as roll dynamic response of the vessel are seen to be in fair quantitative agreement with experimentally measured values of previously published data. Using the 2D + T method, it has been shown that to model the roll of a planing hull at high speeds, we need to consider the effects of heave, pitch, and surge motions. Through our mathematical modeling, it is found that freedom in vertical motions increases time-dependent roll d ing and added mass coefficients, especially at early planing speeds. The results of dynamic response simulations suggest that freedom in the vertical plane can decrease the roll response.
Publisher: Royal Institution of Naval Architects
Date: 2015
DOI: 10.3940/RINA.IJME.2015.A3.336
Abstract: "Submerged T-foils are an essential forward component of the ride control systems of high speed ferries. A model scale T-Foil for a 2.5m towing tank model of a 112m INCAT Tasmania high-speed wave-piercer catamaran has been tested for both static and dynamic lift performance. The tests were carried out using a closed-circuit water tunnel to investigate the lift and drag characteristics as well as frequency response of the T-Foil. The model T-Foil operates at a Reynolds number of approximately 105, has an aspect ratio of 3.6 and a planform which is strongly tapered from the inboard to outboard end. All of these factors, as well as strut and pivot interference, influence the steady lift curve slope of the model T-foil which was found to be 61% of the value for an ideal aerofoil with elliptic loading. The T-foil dynamic performance was limited primarily by the stepper motor drive system and connection linkage. At the frequency of maximum motion of the 2.5 m catamaran model (about 1.5Hz) the model T-foil has approximately 5% reduction of litude and 15 degrees of phase shift relative to the low frequency response. Only very small limitations arose due to the unsteady lift as predicted by the analysis of Theodorsen. It was concluded that the model scale T-foil performed adequately for application to simulation of a ride control system at model scale."
Publisher: The Society of Naval Architects and Marine Engineers
Date: 03-2017
Publisher: The Society of Naval Architects and Marine Engineers
Date: 20-11-190728635
Publisher: Elsevier BV
Date: 05-2020
Publisher: Elsevier BV
Date: 11-2020
Publisher: SAGE Publications
Date: 15-07-2022
DOI: 10.1177/14750902221111122
Abstract: In this paper the influence of a Ride-Control System (RCS) on the Response Amplitude Operator (RAO) of a full-scale high-speed catamaran was investigated using sea trials data. A T-foil and stern tabs were installed on a Wave-Piercing Catamaran (Incat Tasmania Hull 061) to improve ship motions and passenger comfort. More than 40 total effective hours of sea trials were conducted by the US Navy in 2004, encountering sea states 4–5 in the Atlantic Ocean near the United Kingdom. The reduction in Motion Sickness Incidence (MSI) was estimated in order to examine the effectiveness of the RCS in improving passenger comfort. By comparing the case of active RCS (T-foil plus stern tabs) with the case of active stern tabs only, it was found that the T-foil plays a vital role in the passenger comfort enhancement. Based on ISO recommended MSI calculation of a 2-h seaway, the percentage reduction in MSI was estimated, and hence the effectiveness of the T-foil deployment, along with the influence of speeds, headings, location on board and encountered wave height were analysed. A notable improvement in passenger comfort was observed in the real world bow quartering sea by deploying the RCS. An MSI reduction of 21% in high speeds (30–35 knots, [Formula: see text] 0.6) was observed, which was almost twice the MSI reduction (11%) in low speeds (15–20 knots, [Formula: see text] 0.3). However, in terms of MSI percentage reduction, the ability of T-foil in vessel motion control in oblique seas was found to be limited compared to the results in head seas.
Publisher: Springer Science and Business Media LLC
Date: 03-03-2022
DOI: 10.1007/S00773-022-00876-8
Abstract: T-foil and stern tabs were installed on a wave-piercing catamaran (Incat Tasmania Hull 061) to improve ship motions and passenger comfort. More than 40 total effective hours of sea trials were conducted by the US Navy in 2004, encountering sea states 4–5 in the Atlantic Ocean near the United Kingdom. In this paper the influence of a ride-control system (RCS) on the heave and pitch response litude operator (RAO) of the full-scale high-speed catamaran was investigated using the sea trial data. The reduction in motion sickness incidence (MSI) was estimated in order to examine the effectiveness of the RCS in improving passenger comfort. With the existing control algorithm, the vertical accelerations were found to be best controlled by the active T-foil working together with the active stern tabs, while the pitch RAO was mainly mitigated by deploying only the stern tabs. About a 23% reduction was observed in the peak heave RAO with deployment of an active T-foil. The MSI can be reduced by up to 23% with respect to the cases with stern tabs only, depending on the encountered wave conditions, based on ISO recommendation for MSI calculation of a 2-h seaway passage.
Publisher: Royal Institution of Naval Architects
Date: 06-2020
DOI: 10.3940/RINA.IJME.2020.A2.600
Abstract: Determination of hydrodynamic coefficients is a vital part of predicting the dynamic behavior of an Autonomous Underwater Vehicle (AUV). The aim of the present study was to determine the drag and lift related hydrodynamic coefficients of a research AUV, using Computational and Experimental Fluid Dynamics methods. Experimental tests were carried out at AUV speed of 1.5 m s-1 for two general cases: I. AUV without control surfaces (Hull) at various angles of attack in order to calculate Hull related hydrodynamic coefficients and II. AUV with control surfaces at zero angle of attack but in different stern angles to calculate hydrodynamic coefficients related to control surfaces. All the experiments carried out in a towing tank were also simulated by a commercial computational fluid dynamics (CFD) code. The hydrodynamic coefficients obtained from the numerical simulations were in close agreement with those obtained from the experiments.
Publisher: American Society of Mechanical Engineers
Date: 11-06-2023
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 04-2019
No related grants have been discovered for Javad Mehr.