Towing tank test with down thrust methodologyHydrodynamic Laboratory, model basin, University of ... more Towing tank test with down thrust methodologyHydrodynamic Laboratory, model basin, University of Naples Federico II
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
Abstract Laboratory measurements are performed to find the performance in calm water of a planing... more Abstract Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
One of the most efficient methods of reducing drag on planing craft is the use of transverse step... more One of the most efficient methods of reducing drag on planing craft is the use of transverse step on the bottom of a hull. Applying steps on the hull reduces the contact area with water and as a result, it reduces drag of the craft. Planing craft are able to have one or two transverse steps. In this paper, numerical hydrodynamic performance of the stepped planing craft and its step height effect is investigated by making use of finite volume method (FVM). The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with the standard k-ε turbulence model and volume of fluid equations are solved to simulate transient turbulent free surface flow surrounding the hull by ANSYS-CFX. In order to predict the motion of the craft, equations of two degrees of freedom for rigid body are coupled with governing equations of fluid flow. In order to validate the numerical model presented in this paper, the obtained numerical results are compared with the available experimental data. The numerical results obtained for drag, dynamic trim, rising of center of mass and the pressure distribution on the body at different speeds and different heights of the steps are presented and discussed.
Flettner Rotors (FR) are spinning cylinders, which produce fluid dynamic lift by using the Magnus... more Flettner Rotors (FR) are spinning cylinders, which produce fluid dynamic lift by using the Magnus Effect. The Magnus force can be much greater in magnitude than the wing lifting force, given the same projected area and dynamic air pressure. The FR was used for ship's propulsion system in the 1920's. Nowadays, the FR is being seriously examined due to the necessity of renewable resources use. Since several months, the Dipartimento di Ingegneria Industriale of the Università degli Studi di Napoli "Federico II" has started a research about preliminary analysis for marine application of FR through Unsteady Reynolds Average Navier Stokes (U-RANS) simulations for 3D flow past a full-scale rotating [1]. The aerodynamic forces, Lift (L), Drag (D) and Aerodynamic Efficiency (L/D) of a FR are the response variables and are influenced by the following control factors: Spin Ratio (SR), i.e. the ratio of circumferential-cylinder-velocity-to-free streamvelocity; Aspect Ratio (AR), i.e. the ratio between the cylinder length and diameter; Endplate Ratio (De/D 0), i.e. ratio between the endplates diameter and cylinder diameter; In this work, a preliminary assessment of numerical setup has been conducted by comparison with experimental investigation carried out by Badalamenti and Prince at City University of London and published in [2], [3]. The tested cylinder has AR = 5.1, D 0 = 0.0889 m, De/D 0 = 2. A statistical approach based on Design of Experiment (DoE) has been applied to the testing program of FR in order to evaluate the functional relationship and the interaction between the control factors SR, AR and De/D 0 which influence the response variables L, D and L/D. All tests are developed through U-RANS simulations for 3D flow past rotating cylinder. The U-RANS simulations have been performed by using the commercially available flow simulation software CD-Adapco STAR CCM+ v. 9.06.009.
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
It is well known that the dynamic of the stepped hull in real scale is rather complex and it’s no... more It is well known that the dynamic of the stepped hull in real scale is rather complex and it’s not easy to predict that using empirical or mathematical approaches, and by the numerical and experimental way as well. Moreover, there is a huge lack in the literature of data related to sea trials of the stepped hull. Furthermore, the reliability of full-scale CFD simulations is not widely proven and validated especially for high speed and planing hull. For these several reasons, in this paper, the authors are focused on the comparison of the results carried out from model experimental tests performed in the model basin, full-scale CFD simulations, and sea trial tests. The performed simulations in full-scale have been compared to the extrapolated experimental tests and the sea-trial results. Moreover, the dynamic trim angle and the dynamic wetted surface have been taken into account to assess the reliability of the full-scale simulation performed. The stepped hull considered is a Mito 31...
The main goal of the Ph.D. dissertation is to underline how a statistical approach in the plannin... more The main goal of the Ph.D. dissertation is to underline how a statistical approach in the planning and executive phases of the experimental activities, as well as the monitoring of complex systems can both bring real innovations in the maritime field and a higher efficiency in the results. After drawing up the Kyoto protocol, the International Maritime Organization (IMO), the UN Agency in charge for legal questions dealing with the maritime sector, has approved and ratified many measures to reduce the CO2 emissions of ships. For this reason since January 1st, 2013 a higher energy efficiency for ships is required, to be achieved through design and operation choices. During the study for the dissertation it could be shown how the application of appropriate statistical frameworks allowed to meet the goals of recent requirements. In the design step the experiment planning allowed to give designers of high speed crafts information about geometrical details of the stepped hulls. Moreover,...
The competitiveness of the shipping market and the Kyoto Protocol have been urging shipping compa... more The competitiveness of the shipping market and the Kyoto Protocol have been urging shipping companies to pay increasing attention to ship energy efficiency improvement and CO 2 emission reduction. At the same time, new monitoring data acquisition technologies on modern ships have brought to a navigation data overload that need to be correctly handled by shipping companies to make decisions. For this purpose, a novel approach based on the Partial Least-Squares (PLS) regression is introduced for ship fuel consumption monitoring at each voyage. PLS regression naturally deals with complex, correlated and noisy data that usually do not fulfil classical regression model requirements. Moreover, via the contribution plot and the Hotelling control chart for scores , an engineering approach to fault-detection is presented in order to give practical indications on anomalies and/or further navigation variables that need to be technologically investigated.
Laboratory measurements are performed to find the performance in calm water of a planing hull wit... more Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
This work addresses the experimental and numerical study of a stepped planing hull and the relate... more This work addresses the experimental and numerical study of a stepped planing hull and the related fluid dynamics phenomena typically occurring in the stepped hull in the unwetted aft body area behind the step. In the last few years, the interest in high-speed planing crafts, with low weight-to-power ratios, has been increasing significantly, and, in such context, naval architects have been orienting toward the stepped hull solution. Stepped planing hulls ensure good dynamic stability and seakeeping qualities at high speeds. This is mainly due to the reduction of the wetted area, which is caused by the flow separation occurring at the step. This paper presents the experimental results of towing tank tests in calm water on a single-step hull model, which is the first model of a new systematic series. The same flow conditions are analyzed via Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES), with different moving mesh techniques (overset/chimera and morphing gri...
Transportation Research Part D: Transport and Environment
Abstract New regulations in the shipping sector aim to give greater transparency to operations an... more Abstract New regulations in the shipping sector aim to give greater transparency to operations and public access to CO2 emissions data. EU regulation 2015/757 became mandatory in January 2018 and urges shipping companies to set up systems for daily monitoring, reporting and verification (MRV) of emissions for individual ships. Manual acquisition and handling of emissions data may be allowed (e.g. bunker fuel delivery note, bunker fuel tank monitoring), but is adversely affected by uncertainty due to human intervention and will eventually be unusable for monitoring purposes. However, the massive amounts of navigation data acquired by multi-sensor systems installed on-board of modern ships have great potential to aid compliance with regulations but their use is hampered by the lack of effective analytical methods in the maritime literature. This work demonstrates a statistical framework and automatic reporting system for fuel consumption monitoring that addresses the MRV requirements needed to comply with the regulations. The framework has been applied to the Grimaldi Group’s Ro-Ro Pax cruise ships and is shown, in addition, to be capable of supporting fault detection as well as verifying CO2 savings achieved after energy efficiency initiatives.
Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts... more Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower sur...
In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by... more In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in...
Towing tank test with down thrust methodologyHydrodynamic Laboratory, model basin, University of ... more Towing tank test with down thrust methodologyHydrodynamic Laboratory, model basin, University of Naples Federico II
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
Abstract Laboratory measurements are performed to find the performance in calm water of a planing... more Abstract Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
One of the most efficient methods of reducing drag on planing craft is the use of transverse step... more One of the most efficient methods of reducing drag on planing craft is the use of transverse step on the bottom of a hull. Applying steps on the hull reduces the contact area with water and as a result, it reduces drag of the craft. Planing craft are able to have one or two transverse steps. In this paper, numerical hydrodynamic performance of the stepped planing craft and its step height effect is investigated by making use of finite volume method (FVM). The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with the standard k-ε turbulence model and volume of fluid equations are solved to simulate transient turbulent free surface flow surrounding the hull by ANSYS-CFX. In order to predict the motion of the craft, equations of two degrees of freedom for rigid body are coupled with governing equations of fluid flow. In order to validate the numerical model presented in this paper, the obtained numerical results are compared with the available experimental data. The numerical results obtained for drag, dynamic trim, rising of center of mass and the pressure distribution on the body at different speeds and different heights of the steps are presented and discussed.
Flettner Rotors (FR) are spinning cylinders, which produce fluid dynamic lift by using the Magnus... more Flettner Rotors (FR) are spinning cylinders, which produce fluid dynamic lift by using the Magnus Effect. The Magnus force can be much greater in magnitude than the wing lifting force, given the same projected area and dynamic air pressure. The FR was used for ship's propulsion system in the 1920's. Nowadays, the FR is being seriously examined due to the necessity of renewable resources use. Since several months, the Dipartimento di Ingegneria Industriale of the Università degli Studi di Napoli "Federico II" has started a research about preliminary analysis for marine application of FR through Unsteady Reynolds Average Navier Stokes (U-RANS) simulations for 3D flow past a full-scale rotating [1]. The aerodynamic forces, Lift (L), Drag (D) and Aerodynamic Efficiency (L/D) of a FR are the response variables and are influenced by the following control factors: Spin Ratio (SR), i.e. the ratio of circumferential-cylinder-velocity-to-free streamvelocity; Aspect Ratio (AR), i.e. the ratio between the cylinder length and diameter; Endplate Ratio (De/D 0), i.e. ratio between the endplates diameter and cylinder diameter; In this work, a preliminary assessment of numerical setup has been conducted by comparison with experimental investigation carried out by Badalamenti and Prince at City University of London and published in [2], [3]. The tested cylinder has AR = 5.1, D 0 = 0.0889 m, De/D 0 = 2. A statistical approach based on Design of Experiment (DoE) has been applied to the testing program of FR in order to evaluate the functional relationship and the interaction between the control factors SR, AR and De/D 0 which influence the response variables L, D and L/D. All tests are developed through U-RANS simulations for 3D flow past rotating cylinder. The U-RANS simulations have been performed by using the commercially available flow simulation software CD-Adapco STAR CCM+ v. 9.06.009.
Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is repres... more Towing Tank Test of a high speed hull for Rigid Inflatable Boats (RIB). This hull model is representative hull for typical pleasure or military high speed crafts. This model is the hull number C03, one of the eight models of a systematic series tested at the Towing Tank Facility of the University of Naples Federico II, Department of Industrial Engineering. Speed test at Volumetric Froude Number of 3.898. Hull lenght 0.935 m
It is well known that the dynamic of the stepped hull in real scale is rather complex and it’s no... more It is well known that the dynamic of the stepped hull in real scale is rather complex and it’s not easy to predict that using empirical or mathematical approaches, and by the numerical and experimental way as well. Moreover, there is a huge lack in the literature of data related to sea trials of the stepped hull. Furthermore, the reliability of full-scale CFD simulations is not widely proven and validated especially for high speed and planing hull. For these several reasons, in this paper, the authors are focused on the comparison of the results carried out from model experimental tests performed in the model basin, full-scale CFD simulations, and sea trial tests. The performed simulations in full-scale have been compared to the extrapolated experimental tests and the sea-trial results. Moreover, the dynamic trim angle and the dynamic wetted surface have been taken into account to assess the reliability of the full-scale simulation performed. The stepped hull considered is a Mito 31...
The main goal of the Ph.D. dissertation is to underline how a statistical approach in the plannin... more The main goal of the Ph.D. dissertation is to underline how a statistical approach in the planning and executive phases of the experimental activities, as well as the monitoring of complex systems can both bring real innovations in the maritime field and a higher efficiency in the results. After drawing up the Kyoto protocol, the International Maritime Organization (IMO), the UN Agency in charge for legal questions dealing with the maritime sector, has approved and ratified many measures to reduce the CO2 emissions of ships. For this reason since January 1st, 2013 a higher energy efficiency for ships is required, to be achieved through design and operation choices. During the study for the dissertation it could be shown how the application of appropriate statistical frameworks allowed to meet the goals of recent requirements. In the design step the experiment planning allowed to give designers of high speed crafts information about geometrical details of the stepped hulls. Moreover,...
The competitiveness of the shipping market and the Kyoto Protocol have been urging shipping compa... more The competitiveness of the shipping market and the Kyoto Protocol have been urging shipping companies to pay increasing attention to ship energy efficiency improvement and CO 2 emission reduction. At the same time, new monitoring data acquisition technologies on modern ships have brought to a navigation data overload that need to be correctly handled by shipping companies to make decisions. For this purpose, a novel approach based on the Partial Least-Squares (PLS) regression is introduced for ship fuel consumption monitoring at each voyage. PLS regression naturally deals with complex, correlated and noisy data that usually do not fulfil classical regression model requirements. Moreover, via the contribution plot and the Hotelling control chart for scores , an engineering approach to fault-detection is presented in order to give practical indications on anomalies and/or further navigation variables that need to be technologically investigated.
Laboratory measurements are performed to find the performance in calm water of a planing hull wit... more Laboratory measurements are performed to find the performance in calm water of a planing hull with two swept steps. Furthermore, a mathematical model, based on the 2D+T theory, is adapted to provide a fast and accurate simulation for performance prediction of this craft. The trim angle of the vessel is seen to reach to two peaks, one in pre-planing and on in the early planing speed, then converges to a small value around 2 degrees. A small wetted area is seen to appear near the chine of the middle body of the vessel at early planing speed. Laboratory measurements and mathematical computations are seen to be in good agreement, especially at very high-speeds. Overall, the mathematical model is found to be a useful tool for performance prediction of boats with swept steps, which can have different, but better performance in comparison with stepless and boats with transverse steps.
This work addresses the experimental and numerical study of a stepped planing hull and the relate... more This work addresses the experimental and numerical study of a stepped planing hull and the related fluid dynamics phenomena typically occurring in the stepped hull in the unwetted aft body area behind the step. In the last few years, the interest in high-speed planing crafts, with low weight-to-power ratios, has been increasing significantly, and, in such context, naval architects have been orienting toward the stepped hull solution. Stepped planing hulls ensure good dynamic stability and seakeeping qualities at high speeds. This is mainly due to the reduction of the wetted area, which is caused by the flow separation occurring at the step. This paper presents the experimental results of towing tank tests in calm water on a single-step hull model, which is the first model of a new systematic series. The same flow conditions are analyzed via Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulations (LES), with different moving mesh techniques (overset/chimera and morphing gri...
Transportation Research Part D: Transport and Environment
Abstract New regulations in the shipping sector aim to give greater transparency to operations an... more Abstract New regulations in the shipping sector aim to give greater transparency to operations and public access to CO2 emissions data. EU regulation 2015/757 became mandatory in January 2018 and urges shipping companies to set up systems for daily monitoring, reporting and verification (MRV) of emissions for individual ships. Manual acquisition and handling of emissions data may be allowed (e.g. bunker fuel delivery note, bunker fuel tank monitoring), but is adversely affected by uncertainty due to human intervention and will eventually be unusable for monitoring purposes. However, the massive amounts of navigation data acquired by multi-sensor systems installed on-board of modern ships have great potential to aid compliance with regulations but their use is hampered by the lack of effective analytical methods in the maritime literature. This work demonstrates a statistical framework and automatic reporting system for fuel consumption monitoring that addresses the MRV requirements needed to comply with the regulations. The framework has been applied to the Grimaldi Group’s Ro-Ro Pax cruise ships and is shown, in addition, to be capable of supporting fault detection as well as verifying CO2 savings achieved after energy efficiency initiatives.
Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts... more Flow structure is a crucial point for the conceptual design of Wing-in-Ground effect (WIG) crafts. In this study, pressure distributions around a compound wing, velocity and the turbulent intensity distribution in the wake area after trailing of the wing, have been investigated numerically. Computational simulations were completed regarding various angles of attack in-ground-effect. Two parts made up the compound wing: The first composed by one rectangular wing in the center, the second composed by a reverse taper wing, consisting of an anhedral angle at the side. A realizable k-ε turbulent model exhibited the flow field in the physical domain about the wing surface. The numerical results of the compound wing were validated using the data provided by wind tunnel tests. The flow structures around the compound wing were compared with that of a rectangular wing for different conditions. It was found that the pressure distribution on the rectangular wing was weaker than at the lower sur...
In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by... more In the current article, the hydrodynamic forces of single-stepped planing hulls were evaluated by an analytical method and compared against towing tank tests. Using the 2D + T theory, the pressure distribution over the wedge section entering the water and the normal forces acting on the 2D sections have been computed. By integrating the 2D sectional normal forces over the entire wetted length of the vessel, the lift force acting on it has been obtained. Using lift forces as well as the consequence pitch moment, the equilibrium condition for the single-stepped planing hull is found and then resistance, dynamic trim, and the wetted surface are computed. The obtained hydrodynamic results have been compared against the experimental data and it has been observed that the presented mathematical model has reasonable accuracy, in particular, up to Froude number 2.0. Furthermore, this mathematical model can be a useful and fast tool for the stepped hull designers in the early design stage in...
Uploads
Papers by Luigi Vitiello