The main challenges in transport aviation of our time are the reduction of pollutant emission and noise, demanding the development of new technologies able to comply with sustainability requirements. As a result, hybrid-electric powertrains are becoming more and more an enticing choice for companies. The advantage of this technology is given by the possibility to reduce noise and pollution near cities and airports thanks to full electric low altitude flight, in case of ICE based PGS or to a full zero-emission mis-sion in case of fuel cells powered by hydrogen (if produced through electrolysis start-ing from energy of renewable sources). The main purpose of this work is to develop an optimization tool able to preliminary design the aircraft while reducing the powertrain weight to its minimum. Through this procedure the resulting aircraft would be more appealable and competitive, exploiting the hidden potential of this technology. The optimized aircraft should comply with the certification requirements while weighting less than the starting aircraft designed by Hyperion®, a software developed by the Department of Aerospace Science and Tech-nology of the Politecnico di Milano. To do so, a code in MATLAB® was developed. The tool simulates the whole mission that the aircraft is designed to fly while it optimizes the power share between fuel cells and battery in order to reduce the power train weight. Many linear and nonlinear constraints are taken into account by fmincon (an already implemented MATLAB® tool) during this process. In order to study a wider number of cases: liquid hydrogen tank sizing and fuel cells efficiency tool were inte-grated in HyperionOptimal function, while other tools were developed in this occasion such as battery charge and discharge and windmilling recharging simulators. With the intention of validate the new implemented tool, 3 possible retrofit of Dornier 228 (A19a, A18b and A19c respectively) and 3 of ATR 72 aircraft (A70a, A70b and A70c respectively) were studied. Each of the retrofit differs from the other 2 by its value of power density of the fuel cells. This choice is taken with the purpose of showing how the results of the optimizer change when the battery technology becomes more or less appealing. These two classes of aircraft fly two different types of mission, following dif-ferent regulations (CS23 and CS25 respectively) and are thought for a different pur-pose. Furthermore, A70 aircraft were tested also in case of Liquid Hydrogen technology and with windmilling manoeuvre possibility.
La principale sfida dell'aviazione civile moderna riguarda la riduzione dell'inquinamento, compreso l'inquinamento acustico. Una possibile soluzione a questa richiesta di sostenibilità e rispetto per l'ambiente è senz'altro la tecnologia ibrida-elettrica abbinata all'utilizzo di idrogeno come carburante. Questa tecnologia permette di rispettare le richieste sempre più stringenti delle normative lasciando spazio a future implementazioni totalmente "green" in grado di avere impatto zero sull'ambiente. Per questo scopo è stato sviluppato un ottimizzatore basato sul metodo a gradiente inverso in grado di ridurre al minimo il peso del "powertrain" di aerei ibridi-elettrici che sfruttino come carburante idrogeno liquido o gassoso. Attraverso questo disegno preliminare ottimo è possibile raggiungere risultati che sfruttino al meglio il potenziale di questa tecnologia rendendola più competitiva sul mercato. l'ottimizzatore simula la missione di volo e in funzione dei consumi ottimizza la suddivisione della potenza richiesta alle celle a combustibile e alle batterie così da ridurre il peso totale. Per la sua realizzazione sono state implementate o introdotte varie funzioni in grado di dimensionare i serbatoi (nel caso di idrogeno liquido), simulare la carica e la scarica delle batterie, quantificare le performance delle celle a combustibile (in modo accurato se pur preliminare) e simulare l'intera missione di volo comprensiva di alcune varianti come il volo in planata o la ricarica tramite "windmilling".
Optimal approach to the preliminary sizing of hydrogen-driven transport aircraft
Del GRANO, MASSIMILIANO
2020/2021
Abstract
The main challenges in transport aviation of our time are the reduction of pollutant emission and noise, demanding the development of new technologies able to comply with sustainability requirements. As a result, hybrid-electric powertrains are becoming more and more an enticing choice for companies. The advantage of this technology is given by the possibility to reduce noise and pollution near cities and airports thanks to full electric low altitude flight, in case of ICE based PGS or to a full zero-emission mis-sion in case of fuel cells powered by hydrogen (if produced through electrolysis start-ing from energy of renewable sources). The main purpose of this work is to develop an optimization tool able to preliminary design the aircraft while reducing the powertrain weight to its minimum. Through this procedure the resulting aircraft would be more appealable and competitive, exploiting the hidden potential of this technology. The optimized aircraft should comply with the certification requirements while weighting less than the starting aircraft designed by Hyperion®, a software developed by the Department of Aerospace Science and Tech-nology of the Politecnico di Milano. To do so, a code in MATLAB® was developed. The tool simulates the whole mission that the aircraft is designed to fly while it optimizes the power share between fuel cells and battery in order to reduce the power train weight. Many linear and nonlinear constraints are taken into account by fmincon (an already implemented MATLAB® tool) during this process. In order to study a wider number of cases: liquid hydrogen tank sizing and fuel cells efficiency tool were inte-grated in HyperionOptimal function, while other tools were developed in this occasion such as battery charge and discharge and windmilling recharging simulators. With the intention of validate the new implemented tool, 3 possible retrofit of Dornier 228 (A19a, A18b and A19c respectively) and 3 of ATR 72 aircraft (A70a, A70b and A70c respectively) were studied. Each of the retrofit differs from the other 2 by its value of power density of the fuel cells. This choice is taken with the purpose of showing how the results of the optimizer change when the battery technology becomes more or less appealing. These two classes of aircraft fly two different types of mission, following dif-ferent regulations (CS23 and CS25 respectively) and are thought for a different pur-pose. Furthermore, A70 aircraft were tested also in case of Liquid Hydrogen technology and with windmilling manoeuvre possibility.| File | Dimensione | Formato | |
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2021_12_DelGrano.pdf
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https://hdl.handle.net/10589/183637