The present work reports an extensive analysis of solid fuels ballistic behaviours, and of their possible application to an upper stage mission. The first part of the work dealt with the thermochemical analysis of candidate fuel formulations. Fuel formulations based on hydroxyl-terminated polybutadiene (HTPB) and paraffin (SW)-based fuels were considered. Nitrous oxide (N2O) was taken as oxidizer due to its attractive features (high vapor pressure, stable performance over various oxidizer to fuel ratios). Loaded solid fuel formulations were considered, and their relative grading was performed considering HTPB as a reference. Investigated energetic additives include conventional materials as aluminum, and exotic additves as hydrides. The analyzed figures of merit include the vacuum specific impulse, and the condensed combustion products. The second part of the work carried out the ballistic characterization of a selection of the most promising fuels defined by the thermochemical analysis. The aim of this analysis was the regression rate (rf) evaluation with N2O as oxidizer for the tests. Under the tested experimental conditions (chamber pressure of 1.0 MPa, oxidizer mass flow rate of 6 g/s ), SW loaded with 10 wt% of Al showed the best performance in terms of regression rate ( rf ). Considering HTPB as baseline, the percent rf enhancement of the metallized fuel was 669% . The third part of the work concerned the design of an HRE upper stage. This phase aimed to provide a competitive alternative to liquid bi-propellant engines, typically used for this kind of mission. The system used N2O as the oxidizer, exploiting its characteristics of self pressurizing fluid. Engines capable to produce specific impulse comparable to those of AVUM were identified, yielding under the selected design constraints, a system weight reduction.
Il presente lavoro tratta un'analisi estensiva del comportamento balistico di combustibili solidi per la propulsione ibrida, e della loro possibile applicazione ad uno stadio upper stage di lanciatore. Nella prima parte del lavoro è stata trattata l'analisi termochimica di formulazioni combustibili candidate. Sono state considerate formulazioni basate su polibutadiene a terminazioni idrossiliche (HTPB) e paraffina (SW). L'ossido nitroso (N2O) è stato scelto come ossidante grazie alle sue interessanti caratteristiche (alta tensione di vapore, performance stabili su largo intervallo di valori del rapporto di miscela ossidante/combustibile). Sono state considerate formulazioni additivate, scegliendo HTPB come riferimento per la loro valutazione. Gli additivi energetici studiati includono materiali convenzionali come alluminio, ed additivi non convenzionali come idruri metallici. I parametri di merito analizzati includono l'impulso specifico in vuoto e i prodotti di combustione condensati prodotti nella combustione. La seconda parte del lavoro ha trattato la caratterizzazione balistica di una selezione delle più promettenti formulazioni definite dall'analisi termochimica. L'obiettivo di tale analisi è stata la valutazione del rateo di regressione, considerando N2O come ossidante per i test. Sotto le condizioni sperimentali considerate (pressione di camera di 1 MPa, portata massica di ossidante di 6 g/s), la SW additivata con alluminio al 10% in peso ha mostrato le migliori performance in termini di rateo di regressione (rf). Considerando HTPB come base di riferimento l'incremento percentuale di rateo di regressione è stato del 669%. L'ultima parte del lavoro ha trattato il progetto di un upper stage a motore ibrido. L'obiettivo di questa fase è stato fornire un'alternativa competitiva ai motori a bi-propellente liquido, normalmente usati per tale missione. Il sistema ha utilizzato N2O come ossidante, sfruttando le sue caratteristiche di fluido auto-pressurizzante. Sono stati identificati motori capaci di produrre valori di impulso specifico comparabili ad AVUM, fornendo, sotto i vincoli di progetto scelti, una riduzione di peso del sistema.
Solid fuels ballistics and applications to upper stage propulsion
GENCO, FRANCESCO
2016/2017
Abstract
The present work reports an extensive analysis of solid fuels ballistic behaviours, and of their possible application to an upper stage mission. The first part of the work dealt with the thermochemical analysis of candidate fuel formulations. Fuel formulations based on hydroxyl-terminated polybutadiene (HTPB) and paraffin (SW)-based fuels were considered. Nitrous oxide (N2O) was taken as oxidizer due to its attractive features (high vapor pressure, stable performance over various oxidizer to fuel ratios). Loaded solid fuel formulations were considered, and their relative grading was performed considering HTPB as a reference. Investigated energetic additives include conventional materials as aluminum, and exotic additves as hydrides. The analyzed figures of merit include the vacuum specific impulse, and the condensed combustion products. The second part of the work carried out the ballistic characterization of a selection of the most promising fuels defined by the thermochemical analysis. The aim of this analysis was the regression rate (rf) evaluation with N2O as oxidizer for the tests. Under the tested experimental conditions (chamber pressure of 1.0 MPa, oxidizer mass flow rate of 6 g/s ), SW loaded with 10 wt% of Al showed the best performance in terms of regression rate ( rf ). Considering HTPB as baseline, the percent rf enhancement of the metallized fuel was 669% . The third part of the work concerned the design of an HRE upper stage. This phase aimed to provide a competitive alternative to liquid bi-propellant engines, typically used for this kind of mission. The system used N2O as the oxidizer, exploiting its characteristics of self pressurizing fluid. Engines capable to produce specific impulse comparable to those of AVUM were identified, yielding under the selected design constraints, a system weight reduction.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/134050