MARINE VII : proceedings of the VII International Conference on Computational Methods in Marine Engineering, 2017
Due to their higher motion amplitudes and instabilities, numerical simulations of planing hulls u... more Due to their higher motion amplitudes and instabilities, numerical simulations of planing hulls using Computational Fluid Dynamics (CFD) codes are more difficult than that of displacement ships. Indeed, for an accurate evaluation of the hydrodynamic performances of planing craft, the high-fidelity estimation of the pressure field around the hull is crucial. For this reason, validations and comparisons with experimental data are still important to identify the guidelines for both simulation settings and mesh generation. In this paper, two commercial packages will be compared focusing on a resistance case for the parent hull model (C1 hull) from the Naples Systematic Series (NSS) at four Froude numbers (Fr). The NSS is a new systematic series of hard chine hulls intensively tested in planing and semiplaning speed range, De Luca et al. [1]. It has been chosen for the hull form: it is characterized by a warped bottom and a sectional area curve significantly different from the prismatic hulls. These differences amplify the difficulties in finding out the exact pressure distribution on the bottom and, consequently, make the evaluation more stringent. The Unsteady Reynolds-Averaged Navier-Stokes flow solvers results are validated using these benchmark experimental data. Also, grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) follow the recommendations published in the verification and validation (V&V) study from De Luca et al. [2]. Hence, the two software are more compared on different features such as the mesh deformation, the overset method, and the correction of numerical ventilation classically observed below the hull. The results show that both software can provide consistent values and that new guidelines are now identified to improve the reliability of the simulations.
This work is strictly related with the paper " The Naples Warped Hard Chine Hulls Systematic... more This work is strictly related with the paper " The Naples Warped Hard Chine Hulls Systematic Series – First Part: Resistance in Still Water" presented at this same Symposium. The aim of this work is to show the results of the numerical evaluation of the hull-propeller interactions obtained by the commercial RANSE Computational Fluid Dynamic software CD-ADAPCO Star CCM+. In literature there is a significant lack of experimental data on wake and thrust fraction magnitude especially regarding medium and high speed vessels. This is due to the high costs and to the reduced reliability of the tests carried out with small models whose dimensions are constrained by the high Froude numbers. In spite of the high model speed, the smallness of the models induces small Reynolds numbers and therefore not negligible scale effects on propellers dynamic (laminar flow) and on wake intensity. In this paper a numerical analysis has been performed on the parent hull of the series. In particula...
Amid a global effort in reducing the shipping ecologic impact, the study of the particular case o... more Amid a global effort in reducing the shipping ecologic impact, the study of the particular case of added resistance of high speed vessels cruising in a seaway has been approached by a very limited number of authors. In this study, we provide a comprehensive and systematic assessment of the added resistance of a planing hull in regular waves. The data are analyzed in both the time and frequency domains in order to fully characterize the added resistance and highlight its correlation with hull motions. It is found that peak added resistance modulation occurs for shorter waves with respect to the peak average added resistance, and slenderness is beneficial only in terms of modulation. Nonlinearity of both the average and first harmonic amplitude is also shown. In addition, results of the phase analysis show a correlation between the added resistance phase and average added resistance.
The wake waves generated by the steady movement of a planing hull are analyzed by means of towing... more The wake waves generated by the steady movement of a planing hull are analyzed by means of towing tank tests. Two sets of waves, including divergent and transverse waves, are identified and then analyzed. The wave period of the divergent waves is seen to decrease by the increase in speed of the vessel. These waves are seen to damp temporally. The mechanisms that lead to damping of the divergent wave were found to depend on the wave orbital Reynolds number in semi-planing regime, though that of in-planing regime is a function of the Reynolds number of the boat. The wake angle is seen to decrease with the increase in Froude number, the rate of which becomes relatively large in-planing regime. Transverse waves are captured through measurements, and it is shown that while their period is longer than those of the divergent waves, they are not noticeably damped. Throughout the spectral analysis, it is demonstrated that divergent waves reach a higher level of nonlinearity by the increase i...
The Italian Navy has performed a feasibility study about a new OPV (Offshore Patrol Vessel), char... more The Italian Navy has performed a feasibility study about a new OPV (Offshore Patrol Vessel), characterized by very high maximum speeds and a large differences between cruise and full speed. In this study, an attempt has been developed to adequately identify hull forms and to determine the maximum effectiveness of interceptor device to be applied on the displacing hull. Simulations have been carried out by using the RANSE code CD-Adapco STAR CCM+ v. 9.06. To take into account the low reliability of numerical simulations to predict the interceptor’s effectiveness, the towing tank experiences, carried out by INSEAN-CNR Rome on the reference hull form, have been compared with the numerical simulations. Finally, different configurations of hulls have been analyzed to minimize resistance. In addition, for the same aim, different mesh sizes and turbulence models have been tested. In brief, this work is divided into the following parts: • towing tank test experiences; • choice of the more reliable numerical procedure (by validation with towing tank test); • optimization of the hull forms in relation to drag resistance evaluated for the two operational speeds; • identification of interceptor suitable size to be applied to the final hull form. Tests and numerical simulations have been performed for a length model of 8.3 m (14.931 scale), i.e., Reynolds Number (Re) > 2.1 × 107.
This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small... more This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small craft. The main aspects considered are the available propulsion systems, energy storage, and dock battery charging. This underlying activity is part of the KISS project, a research and development program in the frame of the EU-funded “Piano Operativo Regionale CALABRIA FESR-FSE 2014–2020 ASSE I–PROMOZIONEDELLA RICERCA E DELL’INNOVAZIONE”, which is aimed at designing and building a physical prototype. Its hull form is based on previous research conducted by the authors, and the powering performances were preliminarily predicted by CFD simulation. The KISS project represents a successful example of an electric small craft with performances and a mission profile comparable to competitors with conventional propulsion. Such a target has been achieved by a concurrent design that considers the hull form, engine, propulsion system, and energy storage onboard. Safety issues and the regulatory f...
Full scale seakeeping trials are rare, especially planing hull and are in general focused in stud... more Full scale seakeeping trials are rare, especially planing hull and are in general focused in studying bottom pressures, accelerations and vibrations. In this paper, a comprehensive description of the experimental setup and analysis of full scale seakeeping trials propulsion data of a 65 ft planing pleasure yacht is presented. Torque and rpm have been measured on both propeller shafts during seakeeping trials in mild sea conditions, along with hull motions and accelerations. Correlations between hull motions and propulsion data are discussed, both in the time and frequency domain. Further tests on a shaft sample have been carried out in order to validate its mechanical properties and hence quantitative results regarding shaft torque. The main novelty of the present work lays in a detailed analysis of the propulsion system response of a planing pleasure yacht in mild weather conditions.
La tesi affronta lo studio degli interceptor. La principale funzione di questi e la riduzione del... more La tesi affronta lo studio degli interceptor. La principale funzione di questi e la riduzione della resistenza all'avanzamento delle navi veloci. Dispositivi basati su principi simili sono stati applicati in altri contesti (aeronautici, automobilistici, ecc.). Si e ritenuto utile affrontare questo studio per la insufficiente conoscenza della dinamica determinata dall'interferenza interceptor-carena, diversa a causa della presenza dell'interfaccia aria-acqua. Ad oggi, in ambito navale, l'argomento non e mai stato affrontato con procedure sperimentali sistematiche. I risultati ottenuti hanno evidenziato e giustificato la grande efficacia di questi dispositivi se applicati correttamente. La quantita di dati sperimentali ottenuti ha consentito un sostanziale arricchimento della banca dati disponibile in letteratura. In fine, la comprensione del modello fisico ha permesso l’elaborazione di geometrie non convenzionali ed innovative che magnificano le caratteristiche propri...
Abstract The unsteady planing motion in waves is a complicated problem, that can lead to uncomfor... more Abstract The unsteady planing motion in waves is a complicated problem, that can lead to uncomfortable riding situation and structural damages due to large wave-induced dynamic responses and vertical accelerations. In the current research, this problem is investigated using different approaches, including towing tank tests, Computational Fluid Dynamics (CFD), and the 2D + t model. Results obtained from all three approaches are compared against each other in details. The spectral analysis shows that all motions can be nonlinear, but CFD and 2D + t model may predict weaker nonlinear behaviour at higher speed, especially for the case of vertical accelerations corresponding to longer waves. Interestingly, the vertical acceleration found by 2D + t model is seen to be under-predicted at moderate and long wavelengths and to be over-predicted at short waves. The values of sectional forces found by 2D + t model were compared against CFD results, showing that, while the 2D + t model computes smaller sectional forces, it can also compute negative sectional forces near the bow of the vessel at short waves when the boat exits the water. The emergence of negative sectional forces is likely to be the reason why the 2D + t model over-predicts the vertical acceleration in short waves.
In the context of marine application of computational fluid dynamic (CFD), it is well known that ... more In the context of marine application of computational fluid dynamic (CFD), it is well known that the numerical simulations of planing craft are significantly less reliable than that of displacement ships. For this reason, it is important to perform a comprehensive approach to the verification and validation (V&V) methodology and procedures for simulating CFD planing craft. In the first part of this paper, an assessment of the accuracy and effectiveness of different simulation setups and techniques for planing craft is performed. In the second part, the results of the V&V study are reported for three different hull models at four Froude numbers (Fr). The Unsteady Reynolds-Averaged Navier-Stokes code results were validated using benchmark experimental data obtained for three hull models characterized by systematic variation of the length to beam ratio. Grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) were conducted using the main error and uncertainty estimation methods available in the literature. The same procedures were followed for the profiles of the wave patterns. The results showed that there was improved reliability of the numerical simulation of the planing craft in terms of the errors and uncertainties, related to the predictions of resistance, running attitude, and wave pattern. The results of the V&V study highlighted the fact that modeling of the planing craft is a critical point to improve the reliability of the numerical simulation.
Nav 2012 17th International Conference on Ships and Shipping Research, Dec 9, 2012
Data published in 2011 on unconventional interceptors (the Double Interceptors System and the Spl... more Data published in 2011 on unconventional interceptors (the Double Interceptors System and the Split Interceptors) obtained in the towing tank of the Dipartimento di Ingegneria Navale of Naples, point out the high potentiality of these devices. This paper shows data of new tests, performed on D.I.S. and S.I. fitted on three different hull forms. The tests have confirmed the high resistance reductions and the extension of the high efficiency speed range of the hulls. A 20 deg deadrise prismatic and two warped hulls have been tested to evaluate the effects of three different amount of twist of the bottom on the interceptor's efficiency. The warped models are characterized also by different L/B ratios to detect the border effects on the high pressure zone due to the forward device of the D.I.S. . Tests have been performed in the speed range 1.3 5×10 6 . On models fitted with the D.I.S . , longitudinal instability phenomena have been observed at lower speed than the typical ones expected on bare hulls due to purposing. This instability has been related to the ventilation's level downstream the forward device. The experimental procedure has been improved to study in dept these dynamic instability phenomena.
Nav 2012 17th International Conference on Ships and Shipping Research, Dec 9, 2012
The aim of this paper is to present the working principle of an automatic speed and pitch control... more The aim of this paper is to present the working principle of an automatic speed and pitch controller for CPP. The advantage of this kind of propellers becomes relevant when the ship operates in speed and loading conditions quite different from the designed ones; generally the master acts on fixed pairs of propeller pitch and revolution speed, defined in the design stage. In previous works, the authors considered a rpm and pitch control based on direct torque measurements and an offline optimization process, that generated a surface of optimum working points with respect of Kt/J 2 and other parameters. A critique to this method may be that, in this way, the uncertainties on model data affects the optimum working point estimate. In this paper the optimization problem is solved by applying an extremum seeking technique, based on real-time torque shaft (as in the previous work), speed and consumption measurements. Moreover, in order to improve the wake data for the simulated test cases, a series of self-propulsion towing tank tests in different model load condition are carried out.
International Journal of Small Craft Technology, 2018
Abstract –This work reports the flow analysis in the hull-stern region and the hull-propeller int... more Abstract –This work reports the flow analysis in the hull-stern region and the hull-propeller interactions of a Fast Displacement hull using the commercial URANS code CD Adapco Star CCM+. In the present study resistance and selfpropulsion test simulations were conducted to get self-propulsion factors (the wake and thrust deduction factors), using the Computational Fluid Dynamics (CFD) techniques. The computational results were compared with the benchmark towing tank data. The simulation of self-propulsion test is a non-trivial task for the high speed craft, in particular defining the correct trim and so the correct wake field. The reliability of the results is strictly connected to the high quality of the resistance test simulation and to the propeller-modelling method. The purpose of the current study is to provide reliable and fast results of self-propulsion test simulation for the Fast Displacement hulls. For these reasons, starting from different propeller-modelling method (i.e. the Actuator Disk and the Fully Discretized Propeller) the results were compared in terms of accuracy and computational effort.
MARINE VII : proceedings of the VII International Conference on Computational Methods in Marine Engineering, 2017
Due to their higher motion amplitudes and instabilities, numerical simulations of planing hulls u... more Due to their higher motion amplitudes and instabilities, numerical simulations of planing hulls using Computational Fluid Dynamics (CFD) codes are more difficult than that of displacement ships. Indeed, for an accurate evaluation of the hydrodynamic performances of planing craft, the high-fidelity estimation of the pressure field around the hull is crucial. For this reason, validations and comparisons with experimental data are still important to identify the guidelines for both simulation settings and mesh generation. In this paper, two commercial packages will be compared focusing on a resistance case for the parent hull model (C1 hull) from the Naples Systematic Series (NSS) at four Froude numbers (Fr). The NSS is a new systematic series of hard chine hulls intensively tested in planing and semiplaning speed range, De Luca et al. [1]. It has been chosen for the hull form: it is characterized by a warped bottom and a sectional area curve significantly different from the prismatic hulls. These differences amplify the difficulties in finding out the exact pressure distribution on the bottom and, consequently, make the evaluation more stringent. The Unsteady Reynolds-Averaged Navier-Stokes flow solvers results are validated using these benchmark experimental data. Also, grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) follow the recommendations published in the verification and validation (V&V) study from De Luca et al. [2]. Hence, the two software are more compared on different features such as the mesh deformation, the overset method, and the correction of numerical ventilation classically observed below the hull. The results show that both software can provide consistent values and that new guidelines are now identified to improve the reliability of the simulations.
This work is strictly related with the paper " The Naples Warped Hard Chine Hulls Systematic... more This work is strictly related with the paper " The Naples Warped Hard Chine Hulls Systematic Series – First Part: Resistance in Still Water" presented at this same Symposium. The aim of this work is to show the results of the numerical evaluation of the hull-propeller interactions obtained by the commercial RANSE Computational Fluid Dynamic software CD-ADAPCO Star CCM+. In literature there is a significant lack of experimental data on wake and thrust fraction magnitude especially regarding medium and high speed vessels. This is due to the high costs and to the reduced reliability of the tests carried out with small models whose dimensions are constrained by the high Froude numbers. In spite of the high model speed, the smallness of the models induces small Reynolds numbers and therefore not negligible scale effects on propellers dynamic (laminar flow) and on wake intensity. In this paper a numerical analysis has been performed on the parent hull of the series. In particula...
Amid a global effort in reducing the shipping ecologic impact, the study of the particular case o... more Amid a global effort in reducing the shipping ecologic impact, the study of the particular case of added resistance of high speed vessels cruising in a seaway has been approached by a very limited number of authors. In this study, we provide a comprehensive and systematic assessment of the added resistance of a planing hull in regular waves. The data are analyzed in both the time and frequency domains in order to fully characterize the added resistance and highlight its correlation with hull motions. It is found that peak added resistance modulation occurs for shorter waves with respect to the peak average added resistance, and slenderness is beneficial only in terms of modulation. Nonlinearity of both the average and first harmonic amplitude is also shown. In addition, results of the phase analysis show a correlation between the added resistance phase and average added resistance.
The wake waves generated by the steady movement of a planing hull are analyzed by means of towing... more The wake waves generated by the steady movement of a planing hull are analyzed by means of towing tank tests. Two sets of waves, including divergent and transverse waves, are identified and then analyzed. The wave period of the divergent waves is seen to decrease by the increase in speed of the vessel. These waves are seen to damp temporally. The mechanisms that lead to damping of the divergent wave were found to depend on the wave orbital Reynolds number in semi-planing regime, though that of in-planing regime is a function of the Reynolds number of the boat. The wake angle is seen to decrease with the increase in Froude number, the rate of which becomes relatively large in-planing regime. Transverse waves are captured through measurements, and it is shown that while their period is longer than those of the divergent waves, they are not noticeably damped. Throughout the spectral analysis, it is demonstrated that divergent waves reach a higher level of nonlinearity by the increase i...
The Italian Navy has performed a feasibility study about a new OPV (Offshore Patrol Vessel), char... more The Italian Navy has performed a feasibility study about a new OPV (Offshore Patrol Vessel), characterized by very high maximum speeds and a large differences between cruise and full speed. In this study, an attempt has been developed to adequately identify hull forms and to determine the maximum effectiveness of interceptor device to be applied on the displacing hull. Simulations have been carried out by using the RANSE code CD-Adapco STAR CCM+ v. 9.06. To take into account the low reliability of numerical simulations to predict the interceptor’s effectiveness, the towing tank experiences, carried out by INSEAN-CNR Rome on the reference hull form, have been compared with the numerical simulations. Finally, different configurations of hulls have been analyzed to minimize resistance. In addition, for the same aim, different mesh sizes and turbulence models have been tested. In brief, this work is divided into the following parts: • towing tank test experiences; • choice of the more reliable numerical procedure (by validation with towing tank test); • optimization of the hull forms in relation to drag resistance evaluated for the two operational speeds; • identification of interceptor suitable size to be applied to the final hull form. Tests and numerical simulations have been performed for a length model of 8.3 m (14.931 scale), i.e., Reynolds Number (Re) > 2.1 × 107.
This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small... more This paper reviews a state-of-the-art zero emission propulsion system for a battery-powered small craft. The main aspects considered are the available propulsion systems, energy storage, and dock battery charging. This underlying activity is part of the KISS project, a research and development program in the frame of the EU-funded “Piano Operativo Regionale CALABRIA FESR-FSE 2014–2020 ASSE I–PROMOZIONEDELLA RICERCA E DELL’INNOVAZIONE”, which is aimed at designing and building a physical prototype. Its hull form is based on previous research conducted by the authors, and the powering performances were preliminarily predicted by CFD simulation. The KISS project represents a successful example of an electric small craft with performances and a mission profile comparable to competitors with conventional propulsion. Such a target has been achieved by a concurrent design that considers the hull form, engine, propulsion system, and energy storage onboard. Safety issues and the regulatory f...
Full scale seakeeping trials are rare, especially planing hull and are in general focused in stud... more Full scale seakeeping trials are rare, especially planing hull and are in general focused in studying bottom pressures, accelerations and vibrations. In this paper, a comprehensive description of the experimental setup and analysis of full scale seakeeping trials propulsion data of a 65 ft planing pleasure yacht is presented. Torque and rpm have been measured on both propeller shafts during seakeeping trials in mild sea conditions, along with hull motions and accelerations. Correlations between hull motions and propulsion data are discussed, both in the time and frequency domain. Further tests on a shaft sample have been carried out in order to validate its mechanical properties and hence quantitative results regarding shaft torque. The main novelty of the present work lays in a detailed analysis of the propulsion system response of a planing pleasure yacht in mild weather conditions.
La tesi affronta lo studio degli interceptor. La principale funzione di questi e la riduzione del... more La tesi affronta lo studio degli interceptor. La principale funzione di questi e la riduzione della resistenza all'avanzamento delle navi veloci. Dispositivi basati su principi simili sono stati applicati in altri contesti (aeronautici, automobilistici, ecc.). Si e ritenuto utile affrontare questo studio per la insufficiente conoscenza della dinamica determinata dall'interferenza interceptor-carena, diversa a causa della presenza dell'interfaccia aria-acqua. Ad oggi, in ambito navale, l'argomento non e mai stato affrontato con procedure sperimentali sistematiche. I risultati ottenuti hanno evidenziato e giustificato la grande efficacia di questi dispositivi se applicati correttamente. La quantita di dati sperimentali ottenuti ha consentito un sostanziale arricchimento della banca dati disponibile in letteratura. In fine, la comprensione del modello fisico ha permesso l’elaborazione di geometrie non convenzionali ed innovative che magnificano le caratteristiche propri...
Abstract The unsteady planing motion in waves is a complicated problem, that can lead to uncomfor... more Abstract The unsteady planing motion in waves is a complicated problem, that can lead to uncomfortable riding situation and structural damages due to large wave-induced dynamic responses and vertical accelerations. In the current research, this problem is investigated using different approaches, including towing tank tests, Computational Fluid Dynamics (CFD), and the 2D + t model. Results obtained from all three approaches are compared against each other in details. The spectral analysis shows that all motions can be nonlinear, but CFD and 2D + t model may predict weaker nonlinear behaviour at higher speed, especially for the case of vertical accelerations corresponding to longer waves. Interestingly, the vertical acceleration found by 2D + t model is seen to be under-predicted at moderate and long wavelengths and to be over-predicted at short waves. The values of sectional forces found by 2D + t model were compared against CFD results, showing that, while the 2D + t model computes smaller sectional forces, it can also compute negative sectional forces near the bow of the vessel at short waves when the boat exits the water. The emergence of negative sectional forces is likely to be the reason why the 2D + t model over-predicts the vertical acceleration in short waves.
In the context of marine application of computational fluid dynamic (CFD), it is well known that ... more In the context of marine application of computational fluid dynamic (CFD), it is well known that the numerical simulations of planing craft are significantly less reliable than that of displacement ships. For this reason, it is important to perform a comprehensive approach to the verification and validation (V&V) methodology and procedures for simulating CFD planing craft. In the first part of this paper, an assessment of the accuracy and effectiveness of different simulation setups and techniques for planing craft is performed. In the second part, the results of the V&V study are reported for three different hull models at four Froude numbers (Fr). The Unsteady Reynolds-Averaged Navier-Stokes code results were validated using benchmark experimental data obtained for three hull models characterized by systematic variation of the length to beam ratio. Grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) were conducted using the main error and uncertainty estimation methods available in the literature. The same procedures were followed for the profiles of the wave patterns. The results showed that there was improved reliability of the numerical simulation of the planing craft in terms of the errors and uncertainties, related to the predictions of resistance, running attitude, and wave pattern. The results of the V&V study highlighted the fact that modeling of the planing craft is a critical point to improve the reliability of the numerical simulation.
Nav 2012 17th International Conference on Ships and Shipping Research, Dec 9, 2012
Data published in 2011 on unconventional interceptors (the Double Interceptors System and the Spl... more Data published in 2011 on unconventional interceptors (the Double Interceptors System and the Split Interceptors) obtained in the towing tank of the Dipartimento di Ingegneria Navale of Naples, point out the high potentiality of these devices. This paper shows data of new tests, performed on D.I.S. and S.I. fitted on three different hull forms. The tests have confirmed the high resistance reductions and the extension of the high efficiency speed range of the hulls. A 20 deg deadrise prismatic and two warped hulls have been tested to evaluate the effects of three different amount of twist of the bottom on the interceptor's efficiency. The warped models are characterized also by different L/B ratios to detect the border effects on the high pressure zone due to the forward device of the D.I.S. . Tests have been performed in the speed range 1.3 5×10 6 . On models fitted with the D.I.S . , longitudinal instability phenomena have been observed at lower speed than the typical ones expected on bare hulls due to purposing. This instability has been related to the ventilation's level downstream the forward device. The experimental procedure has been improved to study in dept these dynamic instability phenomena.
Nav 2012 17th International Conference on Ships and Shipping Research, Dec 9, 2012
The aim of this paper is to present the working principle of an automatic speed and pitch control... more The aim of this paper is to present the working principle of an automatic speed and pitch controller for CPP. The advantage of this kind of propellers becomes relevant when the ship operates in speed and loading conditions quite different from the designed ones; generally the master acts on fixed pairs of propeller pitch and revolution speed, defined in the design stage. In previous works, the authors considered a rpm and pitch control based on direct torque measurements and an offline optimization process, that generated a surface of optimum working points with respect of Kt/J 2 and other parameters. A critique to this method may be that, in this way, the uncertainties on model data affects the optimum working point estimate. In this paper the optimization problem is solved by applying an extremum seeking technique, based on real-time torque shaft (as in the previous work), speed and consumption measurements. Moreover, in order to improve the wake data for the simulated test cases, a series of self-propulsion towing tank tests in different model load condition are carried out.
International Journal of Small Craft Technology, 2018
Abstract –This work reports the flow analysis in the hull-stern region and the hull-propeller int... more Abstract –This work reports the flow analysis in the hull-stern region and the hull-propeller interactions of a Fast Displacement hull using the commercial URANS code CD Adapco Star CCM+. In the present study resistance and selfpropulsion test simulations were conducted to get self-propulsion factors (the wake and thrust deduction factors), using the Computational Fluid Dynamics (CFD) techniques. The computational results were compared with the benchmark towing tank data. The simulation of self-propulsion test is a non-trivial task for the high speed craft, in particular defining the correct trim and so the correct wake field. The reliability of the results is strictly connected to the high quality of the resistance test simulation and to the propeller-modelling method. The purpose of the current study is to provide reliable and fast results of self-propulsion test simulation for the Fast Displacement hulls. For these reasons, starting from different propeller-modelling method (i.e. the Actuator Disk and the Fully Discretized Propeller) the results were compared in terms of accuracy and computational effort.
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Papers by Fabio de Luca
Displacement hull using the commercial URANS code CD Adapco Star CCM+. In the present study resistance and selfpropulsion
test simulations were conducted to get self-propulsion factors (the wake and thrust deduction factors), using
the Computational Fluid Dynamics (CFD) techniques. The computational results were compared with the benchmark
towing tank data. The simulation of self-propulsion test is a non-trivial task for the high speed craft, in particular
defining the correct trim and so the correct wake field. The reliability of the results is strictly connected to the high
quality of the resistance test simulation and to the propeller-modelling method. The purpose of the current study is to
provide reliable and fast results of self-propulsion test simulation for the Fast Displacement hulls. For these reasons,
starting from different propeller-modelling method (i.e. the Actuator Disk and the Fully Discretized Propeller) the results
were compared in terms of accuracy and computational effort.
Displacement hull using the commercial URANS code CD Adapco Star CCM+. In the present study resistance and selfpropulsion
test simulations were conducted to get self-propulsion factors (the wake and thrust deduction factors), using
the Computational Fluid Dynamics (CFD) techniques. The computational results were compared with the benchmark
towing tank data. The simulation of self-propulsion test is a non-trivial task for the high speed craft, in particular
defining the correct trim and so the correct wake field. The reliability of the results is strictly connected to the high
quality of the resistance test simulation and to the propeller-modelling method. The purpose of the current study is to
provide reliable and fast results of self-propulsion test simulation for the Fast Displacement hulls. For these reasons,
starting from different propeller-modelling method (i.e. the Actuator Disk and the Fully Discretized Propeller) the results
were compared in terms of accuracy and computational effort.