As a consequence of the recent global focus to break down the industrial polluting emissions, technical progress and research have received an important booster from the restrictive regulations ratified by the majority of the most industrialised and, therefore, most polluting countries. Among the several technologies under investigation in maritime sector, an interesting cost-effective use of a wind-assisted propulsion system such as the Flettner rotors can be considered a relevant alternative to diesel engines for general cargo ships, as well as for ferries operating in particularly windy seas. This is why, in fact, all the physical and geometric factors regarding a cargo ship chosen as case-study for this work have been taken into consideration. Indeed, a two-rotor configuration has been considered as installed in a longitudinal manner and with a mutual 15D distance. The present work has been dedicated to the creation of a Power Prediction Program, with the aim to study and optimise the use of Flettner rotors as an alternative to diesel engines on general cargo ships. The created code has been built up in a MATLAB environment to collect some weather information and execute several simulations from a departure to an arrival harbour. As an output of these simulations, the best track on a geographical map is provided to users. From an aerodynamical point of view, the data collected in a Wind Tunnel campaign on models of rotors in Milan were used. To speed up the amount of the required mathematical calculations, while aiming to optimise the usage of the Flettner rotors, the vessel under exam has been firstly considered in a 1-DOF model. However, this first approximation can be considered reductive for a ship, whose trade routes cross seas and oceans, which can be very often stormy and put the manoeuvrability and intact stability of the ship to the test. This is why, a description of the procedures that the code implements for the verification of the manoeuvrability criteria required by the SOLAS regulations and a 6-DOF study was applied in the code. Thanks to the PPP created and described in this analysis, the reduction in diesel consumption represents the driving factor for the calculation by the software of the best route to be suggested to the users of the code. The principal consequences of the reduction of diesel consumption are of fundamental importance in the research and in the commercial field: reduction of CO_2 and NO_x emissions and lower fuel costs for the same time required for the track. In order to evaluate the profit provided by the implementation of Flettner rotors aboard vessels, these results will be the basis for the verification of the minimum criteria imposed by the world regulatory apparatus, by calculating the Energy Efficiency Design Index and verifying how it varies with the use of Flettner rotors. Regarding fuel consumption reduction, an economic analysis of the savings guaranteed by the use of rotors and a forecast of the return on investment for their installation was carried out. As a matter of fact, punctual considerations were made about the several parameters chosen to describe the economic assessments. Lastly, several simulations varying the routes in terms of length, position of the initial and final harbours on a global scale, range of ship speed and rotor dimensions, were carried out to forecast the best wind solution to optimise the return on investment related to the installation of Flettner towers. Several graphs representing the outputs of the calculations are available at the end of the present work, with a discussion on the related advantages and disadvantages. In general, the further the arrival point, the stricter the time in years necessary to cover the initial investment and the bigger the rotor diameter, the more effective the rotor contribution to the ship propulsion. Considering the evident benefits, this work aims to depict how Flettner rotors are a valid solution in terms of both the environmental asset and the economic benefits, considering the free-of-charge use of the wind power, and the payback period estimations deriving from its appropriate usage.
In conseguenza della recente attenzione globale all’abbattimento delle emissioni inquinanti industriali, il progresso tecnologico e la ricerca hanno ricevuto un importante impulso dalle normative ratificate dalla maggior parte dei paesi più industrializzati e, quindi, più inquinanti. Tra le numerose tecnologie allo studio nel settore marittimo, un interessante utilizzo economicamente vantaggioso di un sistema di propulsione assistito dal vento è rappresentato dai rotori di Flettner, che può essere considerato un'alternativa rilevante ai motori diesel per le navi general cargo, così come per i traghetti che operano in aree particolarmente ventose. Nel presente studio, infatti, sono stati presi in considerazione i fattori fisici e geometrici riguardanti una nave da carico, scelta come case-study, e si è considerata una configurazione a doppio rotore. Il presente lavoro è stato dedicato alla creazione di un programma di previsione della potenza (PPP), con l'obiettivo di studiare e ottimizzare l'uso dei rotori di Flettner come alternativa ai motori diesel. Il codice creato è stato realizzato in ambiente MATLAB, per effettuare delle simulazioni sulle tratte coperte dalle navi, dal porto di partenza a quello di arrivo. Come risultato di queste simulazioni, viene fornito il percorso migliore su una mappa geografica. Dal punto di vista aerodinamico sono stati utilizzati i dati raccolti in una campagna in Galleria del Vento del POLIMI su modelli in scala di due rotori. Per accelerare la quantità di calcoli matematici richiesti, garantendo allo stesso tempo l’ottimizzazione dell'utilizzo dei rotori Flettner, la nave in esame è stata inizialmente considerata in un modello 1-DOF. Questa prima approssimazione può però essere considerata riduttiva. Per questo motivo nel codice è stata resa disponibile una descrizione delle procedure che il codice implementa per il calcolo della resistenza all’avanzo in uno studio a sei gradi di libertà. Grazie al PPP realizzato e descritto in questa analisi, la riduzione del consumo di gasolio rappresenta il fattore trainante per il calcolo da parte del software del percorso migliore da suggerire come output. Le principali conseguenze della riduzione del consumo di gasolio sono di fondamentale importanza nella ricerca e nel campo commerciale: riduzione delle emissioni di CO_2 e NO_x e riduzione dei costi del carburante a parità di tempo impiegato. Al fine di valutare il profitto fornito dall’implementazione dei rotori Flettner a bordo delle navi, questi risultati hanno costituito la base per la verifica dei criteri minimi imposti dall’apparato normativo mondiale, calcolando l’EEDI e verificando come esso varia con l’utilizzo di rotori di Flettner. Per quanto riguarda la riduzione del consumo di carburante, è stata effettuata un'analisi economica del risparmio garantito dall'uso dei rotori e una previsione del ritorno sull'investimento per la loro installazione. Infine, sono state effettuate numerose simulazioni variando le rotte in termini di lunghezza, posizione dei porti iniziale e finale su scala globale, intervallo di velocità della nave e dimensioni del rotore, per studiare la variazione del ritorno dell'investimento relativo alla installazione dei rotori. Alla fine del documento sono disponibili diversi grafici che rappresentano i risultati dei calcoli, con una discussione sui relativi vantaggi e svantaggi. In generale, più lontano è il punto di arrivo, minore è il tempo necessario per coprire l'investimento iniziale, e maggiore è il diametro del rotore, più efficace è il contributo del rotore alla propulsione della nave. Considerando i risultati ottenuti, questo lavoro mira a descrivere come i rotori Flettner siano una valida soluzione sia in termini di sostenibilità ambientale che di benefici economici, considerando sia la gratuità dell’energia eolica, e i ridotti periodi di ammortamento derivanti da un suo uso appropriato.
A power prediction program for the optimisation of the usage of Flettner rotors aboard ships
ANGELINI, GIANLUCA
2023/2024
Abstract
As a consequence of the recent global focus to break down the industrial polluting emissions, technical progress and research have received an important booster from the restrictive regulations ratified by the majority of the most industrialised and, therefore, most polluting countries. Among the several technologies under investigation in maritime sector, an interesting cost-effective use of a wind-assisted propulsion system such as the Flettner rotors can be considered a relevant alternative to diesel engines for general cargo ships, as well as for ferries operating in particularly windy seas. This is why, in fact, all the physical and geometric factors regarding a cargo ship chosen as case-study for this work have been taken into consideration. Indeed, a two-rotor configuration has been considered as installed in a longitudinal manner and with a mutual 15D distance. The present work has been dedicated to the creation of a Power Prediction Program, with the aim to study and optimise the use of Flettner rotors as an alternative to diesel engines on general cargo ships. The created code has been built up in a MATLAB environment to collect some weather information and execute several simulations from a departure to an arrival harbour. As an output of these simulations, the best track on a geographical map is provided to users. From an aerodynamical point of view, the data collected in a Wind Tunnel campaign on models of rotors in Milan were used. To speed up the amount of the required mathematical calculations, while aiming to optimise the usage of the Flettner rotors, the vessel under exam has been firstly considered in a 1-DOF model. However, this first approximation can be considered reductive for a ship, whose trade routes cross seas and oceans, which can be very often stormy and put the manoeuvrability and intact stability of the ship to the test. This is why, a description of the procedures that the code implements for the verification of the manoeuvrability criteria required by the SOLAS regulations and a 6-DOF study was applied in the code. Thanks to the PPP created and described in this analysis, the reduction in diesel consumption represents the driving factor for the calculation by the software of the best route to be suggested to the users of the code. The principal consequences of the reduction of diesel consumption are of fundamental importance in the research and in the commercial field: reduction of CO_2 and NO_x emissions and lower fuel costs for the same time required for the track. In order to evaluate the profit provided by the implementation of Flettner rotors aboard vessels, these results will be the basis for the verification of the minimum criteria imposed by the world regulatory apparatus, by calculating the Energy Efficiency Design Index and verifying how it varies with the use of Flettner rotors. Regarding fuel consumption reduction, an economic analysis of the savings guaranteed by the use of rotors and a forecast of the return on investment for their installation was carried out. As a matter of fact, punctual considerations were made about the several parameters chosen to describe the economic assessments. Lastly, several simulations varying the routes in terms of length, position of the initial and final harbours on a global scale, range of ship speed and rotor dimensions, were carried out to forecast the best wind solution to optimise the return on investment related to the installation of Flettner towers. Several graphs representing the outputs of the calculations are available at the end of the present work, with a discussion on the related advantages and disadvantages. In general, the further the arrival point, the stricter the time in years necessary to cover the initial investment and the bigger the rotor diameter, the more effective the rotor contribution to the ship propulsion. Considering the evident benefits, this work aims to depict how Flettner rotors are a valid solution in terms of both the environmental asset and the economic benefits, considering the free-of-charge use of the wind power, and the payback period estimations deriving from its appropriate usage.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/216293