Littérature scientifique sur le sujet « Turbine di Bassa Pressione »

La risonanza magnetica per immagine dell'emorragia subaracnoidea ha un ruolo ben definito nelle fasi subacute: l'efficacia della TC si riduce velocemente, mentre l'accuratezza diagnostica della RM aumenta per l'evidente accorciamento del T1 legato alla metemoglobina ed alla lisi cellulare. La velocity di produzione di metemoglobina e di lisi eritrocitaria sono in relazione con la riduzione della concentrazione locale di glucosio. Nel sistema subaracnoideo una molecola soluta può seguire i gradienti di concentrazione: la concentrazione di glucosio non può, perciò, abbassarsi velocemente, come nelle raccolte parenchimali. Comunque, anche se l'iperintensita in T1 è chiaramente dipendente dalla concentrazione, è possibile riconoscere un'emorragia subaracnoidea anche a basse concentrazioni sangue/liquor, come abbiamo riscontrato in 2 pazienti. Nelle fasi iperacute ed acute la sensibilità della RM è basata principalmente sulla riduzione del T2 causata dalla formazione di deossiemoglobina, mentre il segnale in T1 non subisce importanti modificazioni: la bassa velocity di riduzione della pressione parziale di ossigeno negli spazi subaracnoidei rende difficile distinguere miscele sangue-liquor dal liquor puro. Perciò la diagnosi RM di ESA può essere difficile, come abbiamo riscontrato in due pazienti, ma i coaguli possono offrire un utile ausilio semeiologico. Nelle fasi precoci il segnale dell'ESA è completamente modificato dai processi coagulativi, a causa di un chiaro accorgimento del T1, che diviene evidente durante la retrazione del coagulo. Questo carattere può essere considerato un utile marker in vivo di ESA acuta: è stato cosi possibile valutare una lieve iperintensità silviana in un'ESA acuta altrimenti negativa. D'altra parte bisogna considerare che la coagulazione di miscele sangue/liquor a influenzata da vari fattori biochimici, fisici e topografici, e quindi può presentare aspetti molto differenti e necessita di un esame accurato per essere dimostrata.

Gli animali velenosi sono quelli che hanno un meccanismo per iniettare veleno. Diversi veleni o veleno possono causare dolore, rottura dei vasi sanguigni, ustioni, vesciche, edemi, lesioni necrotiche, emorragia, vomito nel sangue, presenza di sangue nelle urine, sanguinamento nel naso, sudorazione intensa, bassa pressione sanguigna, ipotermia e problemi neurologici. Lo scopo di questo articolo è quello di mostrare il numero di incidenti causati da animali velenosi tra il 2010 e il 2014 in Brasile. Considerate cause trascurate di malattie, gli incidenti causati da animali velenosi richiedono una maggiore attenzione per la salute pubblica. Ragni, scorpioni e serpenti sono i principali causari di questi incidenti. Tra i bambini, i ragazzi sono i più colpiti e la mancanza di supervisione nelle attività quotidiane è una delle principali cause di questo problema. La produzione di siero per il trattamento degli incidenti odidisi in Brasile è accentuata e la quantità prodotta è in grado di coprire il numero totale di casi nel paese. Tuttavia, esiste un problema per quanto riguarda la distribuzione di questo siero, poiché le aree della popolazione indigena e le regioni di località remote non hanno un’adeguata disponibilità, consentendo conseguenze negative per gli individui in questione, aumentando la possibilità di decessi per questo tipo di incidenti.

Low-pressure/high-temperature (LP/HT) metamorphic belts are characterised by rocks that experienced abnormal heat flow in shallow crustal levels (T > 600 °C; P < 4 kbar) resulting in anomalous geothermal gradients (60-150 °C/km). The abnormal amount of heat has been related to crustal underplating of mantle-derived basic magmas or to thermal perturbation linked to intrusion of large volumes of granitoids in the intermediate crust. In particular, in this latter context, magmatic or aqueous fluids are able to transport relevant amounts of heat by advection, thus favouring regional LP/HT metamorphism. However, the thermal perturbation consequent to heat released by cooling magmas is responsible also for contact metamorphic effects. A first problem is that time and space relationships between regional LP/HT metamorphism and contact metamorphism are usually unclear. A second problem is related to the high temperature conditions reached at different crustal levels. These, in some cases, can completely erase the previous metamorphic history. Notwithstanding this problem is very marked in lower crustal levels, petrologic and geochronologic studies usually concentrate in these attractive portions of the crust. However, only in the intermediate/upper-crustal levels of a LP/HT metamorphic belt the tectono-metamorphic events preceding the temperature peak, usually not preserved in the lower crustal portions, can be readily unravelled. The Hercynian Orogen of Western Europe is a well-documented example of a continental collision zone with widespread LP/HT metamorphism, intense crustal anatexis and granite magmatism. Owing to the exposure of a nearly continuous cross-section of the Hercynian continental crust, the Sila massif (northern Calabria) represents a favourable area to understand large-scale relationships between granitoids and LP/HT metamorphic rocks, and to discriminate regional LP/HT metamorphic events from contact metamorphic effects. Granulite-facies rocks of the lower crust and greenschist- to amphibolite-facies rocks of the intermediate-upper crust are separated by granitoids emplaced into the intermediate level during the late stages of the Hercynian orogeny. Up to now, advanced petrologic studies have been focused mostly in understanding P-T evolution of deeper crustal levels and magmatic bodies, whereas the metamorphic history of the shallower crustal levels is poorly constrained. The Hercynian upper crust exposed in Sila has been subdivided in two different metamorphic complexes by previous authors: the low- to very low-grade Bocchigliero complex and the greenschist- to amphibolite-facies Mandatoriccio complex. The latter contains favourable mineral assemblages in order to unravel the tectono-metamorphic evolution of the Hercynian upper crust. The Mandatoriccio complex consists mainly of metapelites, meta-arenites, acid metavolcanites and metabasites with rare intercalations of marbles and orthogneisses. Siliciclastic metasediments show a static porphyroblastic growth mainly of biotite, garnet, andalusite, staurolite and muscovite, whereas cordierite and fibrolite are less common. U-Pb ages and internal features of zircons suggest that the protoliths of the Mandatoriccio complex formed in a sedimentary basin filled by Cambrian to Silurian magmatic products as well as by siliciclastic sediments derived from older igneous and metamorphic rocks. In some localities, metamorphic rocks are injected by numerous aplite/pegmatite veins. Small granite bodies are also present and are always associated to spotted schists with large porphyroblasts. They occur along a NW-SE trending transcurrent cataclastic fault zone, which represents the tectonic contact between the Bocchigliero and the Mandatoriccio complexes. This cataclastic fault zone shows evidence of activity at least from middle-Miocene to Recent, indicating that brittle deformation post-dated the Hercynian orogeny. P-T pseudosections show that micaschists and paragneisses of the Mandatoriccio complex followed a clockwise P-T path characterised by four main prograde phases: thickening, peak-pressure condition, decompression and peak-temperature condition. During the thickening phase, garnet blastesis started up with spessartine-rich syntectonic core developed within micaschists and paragneisses. Coevally (340 ± 9.6 Ma), mafic sills and dykes injected the upper crustal volcaniclastic sedimentary sequence of the Mandatoriccio complex. After reaching the peak-pressure condition (≈4 kbar), the upper crust experienced a period of deformation quiescence marked by the static overgrowths of S2 by Almandine-rich-garnet rims and by porphyroblasts of biotite and staurolite. Probably, this metamorphic phase is related to isotherms relaxation after the thickening episode recorder by the Rb/Sr isotopic system (326 ± 6 Ma isochron age). The post-collisional period was mainly characterised by decompression with increasing temperature. This stage is documented by the andalusite+biotite coronas overgrown on staurolite porphyroblasts and represents a critical point of the metamorphic history, since metamorphic rocks begin to record a significant thermal perturbation. Peak-temperature conditions (≈620 °C) were reached at the end of this stage. They are well constrained by some reaction textures and mineral assemblages observed almost exclusively within paragneisses. The later appearance of fibrolitic sillimanite documents a small excursion of the P-T path across the And-Sil boundary due to the heating. Stephanian U-Pb ages of monazite crystals from the paragneiss, can be related to this heating phase. Similar monazite U-Pb ages from the micaschist combined with the lack of fibrolitic sillimanite suggest that, during the same thermal perturbation, micaschists recorded temperatures slightly lower than those reached by paragneisses. The metamorphic history ended with the crystallisation of cordierite mainly at the expense of andalusite. Consequently, the Ms+Bt+St+And+Sill+Crd mineral assemblage observed in the paragneisses is the result of a polyphasic evolution and is characterised by the metastable persistence of the staurolite in the stability fields of the cordierite. Geologic, geochronologic and petrographic data suggest that the thermal peak recorded by the intermediate/upper crust could be strictly connected with the emplacement of large amounts of granitoid magmas in the middle crust. Probably, the lithospheric extension in the relatively heated crust favoured ascent and emplacement of granitoids and further exhumation of metamorphic rocks. After a comparison among the tectono-metamorphic evolutions of the different Hercynian crustal levels exposed in Sila, it is concluded that the intermediate/upper crustal level offers the possibility to reconstruct a more detailed tectono-metamorphic history. The P-T paths proposed for the lower crustal levels probably underestimate the amount of the decompression. Apart from these considerations, the comparative analysis indicates that P-T paths at various crustal levels in the Sila cross section are well compatible with a unique geologic scenario, characterized by post-collisional extensional tectonics and magmas ascent.

Low-pressure/high-temperature (LP/HT) metamorphic belts are characterised by rocks that experienced abnormal heat flow in shallow crustal levels (T > 600 °C; P < 4 kbar) resulting in anomalous geothermal gradients (60-150 °C/km). The abnormal amount of heat has been related to crustal underplating of mantle-derived basic magmas or to thermal perturbation linked to intrusion of large volumes of granitoids in the intermediate crust. In particular, in this latter context, magmatic or aqueous fluids are able to transport relevant amounts of heat by advection, thus favouring regional LP/HT metamorphism. However, the thermal perturbation consequent to heat released by cooling magmas is responsible also for contact metamorphic effects. A first problem is that time and space relationships between regional LP/HT metamorphism and contact metamorphism are usually unclear. A second problem is related to the high temperature conditions reached at different crustal levels. These, in some cases, can completely erase the previous metamorphic history. Notwithstanding this problem is very marked in lower crustal levels, petrologic and geochronologic studies usually concentrate in these attractive portions of the crust. However, only in the intermediate/upper-crustal levels of a LP/HT metamorphic belt the tectono-metamorphic events preceding the temperature peak, usually not preserved in the lower crustal portions, can be readily unravelled. The Hercynian Orogen of Western Europe is a well-documented example of a continental collision zone with widespread LP/HT metamorphism, intense crustal anatexis and granite magmatism. Owing to the exposure of a nearly continuous cross-section of the Hercynian continental crust, the Sila massif (northern Calabria) represents a favourable area to understand large-scale relationships between granitoids and LP/HT metamorphic rocks, and to discriminate regional LP/HT metamorphic events from contact metamorphic effects. Granulite-facies rocks of the lower crust and greenschist- to amphibolite-facies rocks of the intermediate-upper crust are separated by granitoids emplaced into the intermediate level during the late stages of the Hercynian orogeny. Up to now, advanced petrologic studies have been focused mostly in understanding P-T evolution of deeper crustal levels and magmatic bodies, whereas the metamorphic history of the shallower crustal levels is poorly constrained. The Hercynian upper crust exposed in Sila has been subdivided in two different metamorphic complexes by previous authors: the low- to very low-grade Bocchigliero complex and the greenschist- to amphibolite-facies Mandatoriccio complex. The latter contains favourable mineral assemblages in order to unravel the tectono-metamorphic evolution of the Hercynian upper crust. The Mandatoriccio complex consists mainly of metapelites, meta-arenites, acid metavolcanites and metabasites with rare intercalations of marbles and orthogneisses. Siliciclastic metasediments show a static porphyroblastic growth mainly of biotite, garnet, andalusite, staurolite and muscovite, whereas cordierite and fibrolite are less common. U-Pb ages and internal features of zircons suggest that the protoliths of the Mandatoriccio complex formed in a sedimentary basin filled by Cambrian to Silurian magmatic products as well as by siliciclastic sediments derived from older igneous and metamorphic rocks. In some localities, metamorphic rocks are injected by numerous aplite/pegmatite veins. Small granite bodies are also present and are always associated to spotted schists with large porphyroblasts. They occur along a NW-SE trending transcurrent cataclastic fault zone, which represents the tectonic contact between the Bocchigliero and the Mandatoriccio complexes. This cataclastic fault zone shows evidence of activity at least from middle-Miocene to Recent, indicating that brittle deformation post-dated the Hercynian orogeny. P-T pseudosections show that micaschists and paragneisses of the Mandatoriccio complex followed a clockwise P-T path characterised by four main prograde phases: thickening, peak-pressure condition, decompression and peak-temperature condition. During the thickening phase, garnet blastesis started up with spessartine-rich syntectonic core developed within micaschists and paragneisses. Coevally (340 ± 9.6 Ma), mafic sills and dykes injected the upper crustal volcaniclastic sedimentary sequence of the Mandatoriccio complex. After reaching the peak-pressure condition (≈4 kbar), the upper crust experienced a period of deformation quiescence marked by the static overgrowths of S2 by Almandine-rich-garnet rims and by porphyroblasts of biotite and staurolite. Probably, this metamorphic phase is related to isotherms relaxation after the thickening episode recorder by the Rb/Sr isotopic system (326 ± 6 Ma isochron age). The post-collisional period was mainly characterised by decompression with increasing temperature. This stage is documented by the andalusite+biotite coronas overgrown on staurolite porphyroblasts and represents a critical point of the metamorphic history, since metamorphic rocks begin to record a significant thermal perturbation. Peak-temperature conditions (≈620 °C) were reached at the end of this stage. They are well constrained by some reaction textures and mineral assemblages observed almost exclusively within paragneisses. The later appearance of fibrolitic sillimanite documents a small excursion of the P-T path across the And-Sil boundary due to the heating. Stephanian U-Pb ages of monazite crystals from the paragneiss, can be related to this heating phase. Similar monazite U-Pb ages from the micaschist combined with the lack of fibrolitic sillimanite suggest that, during the same thermal perturbation, micaschists recorded temperatures slightly lower than those reached by paragneisses. The metamorphic history ended with the crystallisation of cordierite mainly at the expense of andalusite. Consequently, the Ms+Bt+St+And+Sill+Crd mineral assemblage observed in the paragneisses is the result of a polyphasic evolution and is characterised by the metastable persistence of the staurolite in the stability fields of the cordierite. Geologic, geochronologic and petrographic data suggest that the thermal peak recorded by the intermediate/upper crust could be strictly connected with the emplacement of large amounts of granitoid magmas in the middle crust. Probably, the lithospheric extension in the relatively heated crust favoured ascent and emplacement of granitoids and further exhumation of metamorphic rocks. After a comparison among the tectono-metamorphic evolutions of the different Hercynian crustal levels exposed in Sila, it is concluded that the intermediate/upper crustal level offers the possibility to reconstruct a more detailed tectono-metamorphic history. The P-T paths proposed for the lower crustal levels probably underestimate the amount of the decompression. Apart from these considerations, the comparative analysis indicates that P-T paths at various crustal levels in the Sila cross section are well compatible with a unique geologic scenario, characterized by post-collisional extensional tectonics and magmas ascent.

Scopo di questo lavoro di tesi risulta essere quello di cercare di studiare e verificare la fattibilità dell’utilizzo della tecnologia ORC per un’applicazione differente, in linea con i principi di funzionamento e le peculiarità che caratterizzano questo tipo di tecnologia: si è cercato di progettare un impianto ORC alimentato da fonte solare, per mezzo di collettori termici, capace di produrre potenza meccanica utile da sfruttare non più per la semplice generazione elettrica (generatore elettrico azionato dalla rotazione dell’albero collegato all’espansore), ma da trasferire ad un compressore calettato sullo stesso albero che può così alimentare una sorta di gruppo frigo a compressione; in questo modo si riesce ad utilizzare il calore prodotto dalla fonte solare per produrre un effetto frigorifero utile da poter sfruttare, similmente alle varie applicazioni di solar cooling esistenti. Questo ciclo moto-operatore solare riesce ad auto-alimentarsi senza bisogno di energia elettrica dall’esterno, sfruttando solamente la potenza meccanica sviluppata dall’espansione del fluido organico in turbina, capace di trascinare compressore e pompa e dare un effetto frigorifero in uscita, configurandosi così come impianto da poter utilizzare potenzialmente anche in remoto e in grado di apportare un effetto utile essenzialmente in maniera “gratuita”, sfruttando solamente la radiazione solare incidente sui collettori.

The trend of CO2 emission limit and fuel saving due to the oil price increase and are important drivers for engines development. The engine auxiliary devices electrification (g.e fuel pump) is a way to reduce the energy consumption, because it becomes possible to control them depending on engine operation point, this kid of management can be applied to the electric low-pressure pump. Usually the fuel delivery is performed at the maximum flow rate and a pressure regulator discharges the exceeding fuel amount inside the rail (gasoline engine) or upstream of the high pressure pump (common rail diesel engine). In this work it has been investigated the fuel saving achievable through a proper control of the electric fuel pump on a small common rail diesel engine, and a control architecture is proposed. The aim was to maximize the fuel economy without any impact on pressure control in the engine transient conditions. L'andamento del limite di emissioni di CO2 e il risparmio di carburante dovuto all'aumento del prezzo del petrolio sono fattori importanti per lo sviluppo dei motori. I dispositivi ausiliari, come la pompa del carburante, sono un modo per ridurre il consumo energetico, in quanto diventa possibile controllarli a seconda del punto di funzionamento del motore, questo tipo di gestione può essere applicato alla pompa elettrica a bassa pressione. Solitamente la portata del combustibile viene eseguita alla portata massima e un regolatore di pressione si scarica la quantità eccedente di carburante all'interno del rail (motore a benzina) o a monte della pompa a alta pressione (common rail motore diesel). In questo lavoro è stato studiato il risparmio di combustibile ottenibile attraverso un adeguato controllo della pompa elettrica del carburante su un piccolo motore diesel common rail e viene proposta una architettura di controllo. Lo scopo è quello di massimizzare il risparmio di carburante, senza alcun impatto sul controllo della pressione nelle condizioni transitorie del motore.

Atrial fibrillation (AF) is a common arrhythmia characterized by irregular ventricular response. During AF, beat-to-beat variability of arterial pressure (AP) is increased because of continuous changes in filling time, stroke volume and contractility. Only a few studies have analyzed short-term AP variability during AF but they were mainly focused on the effects of respiration. We therefore analyzed short-term systolic (S), diastolic (D) and mean (M) AP variability by autoregressive method and an FFT-based spectral estimation (Welch periodogram) in 26 patients with persistent AF before and after restoration of sinus rhythm by electrical cardioversion. A low frequency (LF) component (central frequency 0.07±0.02 Hz, mean±standard deviation) of SAP variability was observed in 23 out of 26 patients during AF. Frequency analysis of DAP and MAP also showed a LF component with a central frequency of 0.08±0.03 Hz (20 patients) and 0.07±0.03 Hz (25 patients), respectively. After recovery of sinus rhythm, we found significant reduction in mean SAP, DAP and MAP variability in all frequency bands. Squared coherence between SAP and heart rate variability after recovery of sinus rhythm revealed a weak and strong coupling within, respectively, LF and HF frequency bands. These data indicate that in patients with AF, in spite of an absence of rhythmical oscillation in RR interval time series, it is possible to observe a LF component in SAP, DAP and MAP variability signals. These 0.1 Hz fluctuations reflect the influence of the sympathetic fibres acting on the cardiovascular system. During atrial fibrillation (AF), ventricular response is highly irregular and thus the beat-to-beat variation of blood pressure is increased because of variations in filling time and in contractility. Aim of the present study is to investigate the short-term dynamics of RR and SAP series in patients with AF, during rest and tilt, and after restoration of sinus rhythm. We computed symbolic sequences of the three phases, as they retain important features of the dynamics generated by the underlying control system. Then we applied a method based on rank order statistics of symbolic sequences to investigate the profile of different types of dynamics. The linguistic distance (range 0–1) between sequences represents a measure of similarity to assess whether the different physiological states are reflected on the dynamics of RR and SAP series. The distance between rest and tilt phases is 0.06 ± 0.02 for RR series, meaning they are very similar, while it is 0.21 ± 0.13 for SAP series, showing a difference in the short term dynamics. RR mean decreases during tilt (738 ± 164 vs. 692 ± 152 ms, p < 0.05, rest vs. tilt), while mean SAP is not significantly different (101 ± 20 vs. 104 ± 14 mmHg, rest vs. tilt). Comparing AF and sinus rhythm, both RR and SAP series result different in terms of the computed distance. SAP short-term dynamics seem to significantly change when comparing rest and tilt phases, while RR series remain unchanged. Moreover, RR mean but not SAP series significantly decreased during tilt.

La tesi "Analisi del ciclo di lavorazione e dei costi di trattamenti termici" è stata svolta in collaborazione con l'azienda PASELLO TRATTAMENTI TERMICI s.r.l. che si occupa di trattamenti termici dei metalli per conto terzi. L’obiettivo è svolgere l’analisi del ciclo di lavorazione e dei costi di due prodotti ricevuti in conto lavoro dall’azienda, confrontando i trattamenti termici di cementazione in atmosfera e a bassa pressione. Nel capitolo 1 sono descritti i tratti generali dell’azienda, le risorse produttive di cui dispone e come vengono gestite l’identificazione e la tracciabilità dei prodotti durante il processo produttivo. Nel capitolo 2 viene analizzato il ciclo di lavorazione in atmosfera di un prodotto del cliente Sarbo Spa, sottoposto al trattamento termico di cementazione in atmosfera. Dunque vengono descritti il trattamento termico e le caratteristiche principali dei pezzi. Allo stesso modo, nel capitolo 3, viene analizzato il ciclo di lavorazione in bassa pressione di un prodotto del cliente Seven Diesel Spa, sottoposto al trattamento termico di cementazione a bassa pressione. Nel capitolo 4 viene svolta l’analisi dei costi, secondo la logica “full costing”, tenendo distinti i due ordini e determinando il costo industriale. Vengono analizzati gli investimenti nelle due linee, i costi di ammortamento, i costi dei materiali di consumo, i costi di manodopera e i costi dei gas di processo, fino a determinare il costo totale di fornata per la cementazione in atmosfera e per la cementazione a bassa pressione, e quindi l’euro al chilo e al pezzo dei due ordini. Inoltre è quantificata l’incidenza dei costi in percentuale sul costo totale di fornata. Nella conclusione viene sottolineato il fatto che, nonostante l’investimento in una linea innovativa come quella a bassa pressione sia superiore rispetto a quello per la linea in atmosfera, se si considera l’intero processo produttivo, risulta più conveniente la cementazione in bassa pressione.

Nell’elaborato vengono descritti ed analizzati i cicli reali e le irreversibilità nelle turbomacchine: i compressori centrifughi, le turbine radiali, le turbine a gas e le turbine a vapore. Gli obiettivi sono analizzare e trattare le tipologie principali delle perdite energetiche e i modelli principali per calcolare le perdite di trattamento delle irreversibilità. In questa tesi sono descritte le tipologie di perdite energetiche e le perdite di pressione totali relative alle turbomacchine e sono riportare le simulazioni eseguite mediante Ansys Fluent, un software per disegnare le strutture dei componenti delle macchine a fluido e analizzare la termo-fluidodinamica durante il funzionamento delle turbomacchine.

L’infissione nel fondale marino di pali in acciaio di grandi dimensioni costituenti la sottostruttura delle turbine eoliche provoca la nascita e la propagazione di un campo di vibrazioni inquinanti. Tali vibrazioni, le quali possono raggiungere elevate distanze, se al di sopra di particolari soglie di intensità, possono causare danni temporanei o permanenti, di natura fisiologica o comportamentale, alle forme di vita acquatiche circostanti il sito di collocamento dell’elemento strutturale. Tuttavia, diverse soluzioni sono state ideate per ridurne gli effetti nocivi: una di queste è il sistema air-bubble curtain. Tramite questo elaborato, si procede, in un primo momento, allo studio ed all’approfondimento delle equazioni governanti il problema vibro-acustico unitamente all’interazione con il sistema di dissipazione. Successivamente, si sfrutta il software di calcolo COMSOL Multiphysics per la creazione dei modelli necessari allo studio delle caratteristiche del sistema dissipativo. L’indagine ha interessato i parametri di distanza dal palo di fondazione, spessore della cortina di bolle, frazione di volume d’aria nella miscela, numero degli strati attorno al palo e forma di modellazione. Si è così riscontrato che il fattore che incide maggiormente sull’attenuazione del segnale è la frazione di volume d’aria nella miscela acqua-aria (poco influiscono spessore ed il numero di strati). Tuttavia, un’adeguata distanza tra dispositivo e sorgente sonora garantisce un’efficace azione smorzante unitamente ad uno spazio di lavoro modesto. L’assunzione di una forma più prossima a quella reale lascia comunque dei dubbi relativamente ad una maggiore efficacia.

The present thesis deals with the generation of innovative design solutions for reducing aerodynamic losses in Low-Pressure Turbines through the combined use of Artificial Neural Networks and CFD (Computational Fluid Dynamics). In particular, a lean model for optimizing blade airfoils in a multi-row environment and the development of a passive control device for reducing secondary losses are presented. The first procedure allows building a 1.5 stage by starting from a single blade profile, which is one of the main focuses of low TRL (Technology Readiness Level) design activities. In the obtained setup, two airfoil aerodynamic optimizations are performed by considering steady and unsteady conditions separately. The evaluation of the unsteady phenomena proves to be critical already at the considered blade design stage. Indeed, such practice allows achieving better aerodynamic performance and reducing the blade count per row. The second part of the thesis explains the blade fence development, which has been performed in collaboration with Avio Aero and Università degli Studi di Genova (UniGE). Such shelf-like devices are applied onto the blade surface to hinder the generation of secondary flows. The blade fence shape is the result of numerical aerodynamic optimizations so that the devices determine the reduction not only of the secondary loss but also of the flow turning deviation at the vane outlet. Such beneficial effects are also confirmed by the results of the experimental campaign conducted by UniGE on linear cascades.