Estimation of the total mission life of a spacecraft is an important issue for the communication satellite industries. For accurate determination of the remaining mission life of the satellite it is essential to estimate the amount of propellant present in the propellant tank of the spacecraft at various stages of its mission life. Because the annual revenue incurred from a typical commu-nication satellite operating at its full capacity is on the order of millions of dollars, premature removal of spacecraft from their orbits results in heavy losses. Various techniques such as the bookkeeping method, the gas law method, numerical modeling techniques, and use of capacitive sensors have been employed in the past for accurate determination of the amount of propellant present in a spacecraft. First half of the thesis is concerned with sensitivity analysis of the various propellant gauging techniques, that is, estimating the effects of the uncertainty in the instruments employed in the propellant gauging system on the onboard propellant estimation. This sensitivity analysis is done for three existing propellant gauging techniques – gas injection method, book-keeping method and the propellant tank heating method. A comparative study of the precision with which the onboard propellant is estimated by the three techniques is done and the primary source of uncertainty for all the three techniques is identified. It is illustrated that all the three methods — the gas injection method, the book-keeping method and the propellant tank heating method — are inherently indirect methods of propellant gauging, as a consequence of which, the precision with which the three techniques estimate the residual propellant decreases towards the end of mission life of the spacecraft. The second half of the thesis explores the possibility of using a new propellant tank configuration, consisting of a truncated cone centrally mounted within a spherical propellant tank, to measure the amount of liquid propellant present within the tank. The liquid propellant present within the propellant tank orients itself in a geometry, by virtue of its dominant surface tension force in zero-g condition, which minimizes its total surface energy. Study reveals that the amount of liquid propellant present in the tank can thus be estimated by measuring the height of the propellant meniscus within the central cone. It is also observed that, unlike gas law method, bookkeeping method or the propellant tank heating method, where the precision of the estimated propellant fill-fraction decreases towards the end-of-life of the spacecraft, for the proposed new configuration the precision increases.

Hydrazine and monomethylhydrazine are widely used as propellants in aerospace and defense industries. However these chemicals are volatile, carcinogenic, and sensitive to impact, which impose serious threats during their usage. In this thesis, we have demonstrated two novel ways to immobilize hydrazine chemicals. In one approach hydrazine, monomethylhydrazine have been gelled using carbon dioxide. Chemical and structural properties of these gels are studied by NMR (1H, 15N, 13C), diffusion-ordered NMR spectroscopy, and Cryo-HRSEM. Thermal reversibility of these gels is also demonstrated. In another approach, hydrazine, monomethylhydrazine and 1,1-dimethylhydrazine are reacted with 5-methyltetrazole to form ionic liquids. Synthesis of novel tetrazole monomers and polymers, .and new method for encapsulating sodium azide have also reported in this thesis

Thèse (M.Eng.) -- Université du Québec à Chicoutimi, programme extensionné à l'Université du Québec à Rimouski, 2003. / Bibliogr.: f. 107-112. Document électronique également accessible en format PDF. CaQCU

Ce travail se consacre à la simulation numérique tridimensionnelle de suspensions denses, monodispersés, non-inertielles et non-colloïdales. Nous avons pour ce faire développé une méthode numérique basée sur une approche de type domaine fictif. Le modèle inclut également une modélisation détaillée des forces de lubrification ainsi que des forces de contact avec prise en compte des rugosités et du frottement. Un résultat majeur est le rôle important du frottement entre particules sur la rhéologie de la suspension – en particulier sur la viscosité de cisaillement et les contraintes normales – mais aussi sur la viscosité normale ou la diffusion des particules. Le frottement contribue à augmenter fortement la contrainte de contact alors que la contrainte hydrodynamique n’est quasiment pas affectée. Cette contrainte de contact s’avère être la contrainte majoritaire dans les suspensions denses. La prise en compte du frottement dans les simulations permet de se rapprocher notablement des résultats expérimentaux. Le rôle du confinement est également étudié et les parois s’avèrent conduire à une organisation locale marquée de type hexagonal ainsi qu’à un glissement. Cette organisation entraîne des effets sensibles sur les propriétés rhéologiques surtout pour la première différence de contraintes normales N1 qui peut localement devenir positive. Enfin, nous abordons l’impact d’amas percolants de particules dans la suspension. La fraction volumique de percolation se situe entre 0,3 et 0,4 avec un effet marqué de la rugosité, du frottement et de la taille du domaine. / This work is devoted to three-dimensional numerical simulations of monodisperse non-inertial non-colloidal concentrated suspensions. To this end, a numerical method based on a fictitious domain technique is developed. It includes a detailed lubrication model as well as a contact model allowing for particle roughness and friction. One major result is the strong effect of friction on rheology, especially on shear viscosity and normal stresses. It also alters markedly normal viscosity or particle diffusion. Friction acts mostly through an increase in the contact stress since the hydrodynamic stress remains unaffected. This contact stress occurs to be the prevailing stress in dense suspensions. Overall, frictional results are in much better agreement with available experiments. The role of confinement is investigated as well and walls are shown to induce a strong local hexagonal ordering with a significant wall slip. This wall-induced ordering has a notable effect on rheology, especially on the first normal stress difference N1 that can be locally positive. Finally, we have studied the percolation of particle clusters across the suspension. The critical volume fraction is found to be in the range 0.3~0.4, with a significant dependence on roughness, friction, and domain size. Percolating clusters characteristics can globally be described by an isotropic percolation theory, with discrepancies regarding some critical exponents however. The role of percolating clusters on rheology is found to be very limited.

To enable future environmentally friendly access to space by means of solid rocket propulsion a viable replacement to the hazardous ammonium perchlorate oxidizer is needed. Ammonium dinitramide (ADN) is one of few such compounds currently known. Unfortunately compatibility issues with many polymer binder systems and unexplained solid-state behavior have thus far hampered the development of ADN-based propellants. Chapters one, two and three offer a general introduction to the thesis, and into relevant aspects of quantum chemistry and polymer chemistry. Chapter four of this thesis presents extensive quantum chemical and spectroscopic studies that explain much of ADN’s anomalous reactivity, solid-state behavior and thermal stability. Polarization of surface dinitramide anions has been identified as the main reason for the decreased stability of solid ADN, and theoretical models have been developed to explain and predict the solid-state stability of general dinitramide salts. Experimental decomposition characteristics for ADN, such as activation energy and decomposition products, have been explained for different physical conditions. The reactivity of ADN towards many chemical groups is explained by ammonium-mediated conjugate addition reactions. It is predicted that ADN can be stabilized by changing the surface chemistry with additives, for example by using hydrogen bond donors, and by trapping radical intermediates using suitable amine-functionalities. Chapter five presents several conceptual green energetic materials (GEMs), including different pentazolate derivatives, which have been subjected to thorough theoretical studies. One of these, trinitramide (TNA), has been synthesized and characterized by vibrational and nuclear magnetic resonance spectroscopy. Finally, chapter six covers the synthesis of several polymeric materials based on polyoxetanes, which have been tested for compatibility with ADN. Successful formation of polymer matrices based on the ADN-compatible polyglycidyl azide polymer (GAP) has been demonstrated using a novel type of macromolecular curing agent. In light of these results further work towards ADN-propellants is strongly encouraged. / QC 20101103

Ce travail de thèse vise à identifier les mécanismes par lesquels la fraction volumique de charges, la distribution de tailles des charges, le comportement mécanique du liant et les propriétés d’adhésion liant/charge des propergols composites influent sur le comportement mécanique jusqu’à rupture de ces matériaux. Des calculs de microstructures 2D par éléments finis sont mis en œuvre pour caractériser qualitativement l’évolution de la microstructure du composite au cours d’une sollicitation de traction uniaxiale à faible vitesse de déformation. Ils prennent notamment en compte un modèle de zone cohésive pour représenter la décohésion à l’interface liant/charge et un critère original de ruine de la microstructure. Les résultats numériques sont favorablement comparés aux tendances obtenues expérimentalement sur propergols composites industriels et modèles. Par ailleurs, une validation de l’approche qualitative précédente est conduite en effectuant une confrontation quantitative du comportement mécanique et de la variation volumique d’un composite modèle, obtenus par simulation de microstructures 3D et par caractérisations expérimentales. Enfin, la tenue du propergol dans un assemblage propergol/lieur soumis à un test de pelage est étudiée expérimentalement. / This work aims at understanding the relationship between solid propellants particles volume fraction, particles size distribution, binder mechanical properties and binder/particles bonding with the mechanical behavior up to failure of these materials. Finite elements analyses on 2D microstructures are performed in order to qualitatively characterize the microstructure evolution throughout uniaxial tensile loading at small strain rate. These simulations account for the binder/particles debonding with a cohesive zone model and implement an original failure criterion. Simulation and experimental results are consistent. Besides, a quantitative comparison between simulations on 3D microstructures and experimental data is drawn in order to validate the above qualitative results. It is performed on a model composite and compares both the mechanical behavior and the volume variations. At last, the propellant failure during a peeling test of the liner/propellant structure is studied experimentally.

This thesis presents the results and analyses of computational studies on certain problems of combustion instability in solid propellants. Specifically, effects of relaxing certain assumptions made in previous models of unsteady burning of solid propellants are investigated. Knowledge of unsteady burning of solid propellants is essential in studying the phenomenon of combustion instability in solid propellant rocket motors. In Chapter 1, an introduction to different types of unsteady combustion investigated in this thesis, such as 1) intrinsic instability, 2) pressure-driven dynamic burning, 3) extinction by depressurization, and 4) L* -instability, is given. Also, a review of previous experimental and theoretical studies of these phenomena is presented. From this review it is concluded that all the previous studies, which investigated the unsteady combustion of solid propellants, made one or more of the following assumptions: 1) quasi-steady gas-phase (QSG), 2) quasi-steady condensed phase reaction zone (QSC), 3) small perturbations, and 4) unity Lewis number. These assumptions limit the validity of the results obtained with such models to: 1) relatively low frequencies (< 1 kHz) of pressure oscillations and 2) small deviations in pressure from its steady state or mean values. The objectives of the present thesis are formulated based on the above conclusions. These are: 1) to develop a nonlinear numerical model of unsteady solid propellant combustion, 2) to relax the assumptions of QSG and QSC, 3) to study the consequent effects on the intrinsic instability and pressure-driven dynamic burning, and 4) to investigate the L* -instability in solid propellant rocket motors. In Chapter 2, a nonlinear numerical model, which relaxes the QSG and QSC assumptions, is set up. The transformation and nondimensionalization of the governing equations are presented. The numerical technique based on the method of operator-splitting, used to solve the governing equations is described. In Chapter 3, the effect of relaxing the QSG assumption on the intrinsic instability is investigated. The stable and unstable solutions are obtained for parameters corresponding to a typical composite propellant. The stability boundary, in terms of the nondimensional parameters identified by Denison and Baum (1961), is predicted using the present model. This is compared with the stability boundary obtained by previous linear stability theories, based on activation energy asymptotics in the gas-phase, which employed QSC and/or QSG assumptions. It is found that in the limit of large activation energy and low frequencies, present result approaches the previous theoretical results. This serves as a validation of the present method of solution. It is confirmed that relaxing the QSG assumption widens the stable region. However, it is found that a distributed reaction in the gas-phase destabilizes the burning. The effect of non-unity Lewis number on the stability boundary is also investigated. It is found that at parametric values corresponding to low pressures and large flame stand-off distances, small amplitude, high frequency (at frequencies near the characteristic frequency of the gas-phase) oscillations in burning rate appear when the Lewis number is greater than one. In Chapter 4, the effect of relaxing the QSG assumption is further investigated with respect to the pressure-driven dynamic burning. Comparison of the pressure-driven frequency response function, Rp, obtained with the present model, both in the QSG and non-QSG framework, with those obtained with previous linear stability theories invoking QSG and QSC assumptions are made. As the frequency of pressure oscillations approaches zero, |RP| predicted using present models approached the value obtained by previous theoretical studies. Also, it is confirmed that the effect of relaxing QSG is to decrease the |Rp| at frequencies near the first resonant frequency. Moreover, relaxing QSG assumption produces a second resonant peak in |Rp| at a frequency near the characteristic frequency of the gas-phase. Further, Rp calculated using the present model is compared with that obtained by a previous linear theory which relaxed the QSG assumption. The two models predicted the same resonant frequencies in the limit of small amplitudes of pressure oscillations. Finally, it is found that the effect of large amplitude of pressure oscillations is to introduce higher harmonics in the burning rate and to reduce the mean burning rate. In Chapter 5, first the present non-QSC model is validated by comparing its results with that of a previous non-QSC model for radiation-driven burning. The model is further validated for steady burning results by comparing with experimental data for a double base propellant (DBP). Then, the effect of relaxing the QSC assumption on steady state solution is investigated. It is found that, even in the presence of a strong gas-phase heat feedback, QSC assumption is valid for moderately large values of condensed phase Zel'dovich number, as far as steady state solution is concerned. However, for pressure-driven dynamic burning, relaxing the QSC assumption is found to increase |RP| at all frequencies. The error due to QSC assumption is found to become significant, either when |Rp| is large or as the driving frequency approaches the characteristic frequency of the condensed phase reaction zone. The predicted real part of the response function is quantitatively compared with experimental data for DBP. The comparison seems to be better with a value of condensed phase activation energy higher than that suggested by Zenin (1992). In Chapter 6, burning rate transients for a DBP during exponential depressurization are computed using non-QSG and non-QSC models. Salient features of extinction and combustion recovery are predicted. The predicted critical initial depressurization rate, (dp/dt)i, is found to decrease markedly when the QSC assumption is relaxed. The effect of initial pressure level on critical (dp/dt)i is studied. It is found that the critical (dp/dt)i decreases with the initial pressure. Also, the overshoot of burning rate during combustion recovery is found to be relatively large with low initial pressures. However as the initial pressure approached the final pressure, the reduction in initial pressure causes a large increase in the critical (dp/dt)i. No extinction is found to occur when the initial pressure is very close to the final pressure. In Chapter 7, a numerical model is developed to simulate the L* -instability in solid propellant motors. This model includes a) the propellant burning model that takes into account nonlinear pressure oscillations and that takes into account an unsteady gas- and condensed phase, and b) a combustor model that allows pressure and temperature oscillations of finite amplitude. Various regimes of L* -burning of a motor, with a typical composite propellant, namely 1) steady burning, 2) oscillatory burning leading to steady state, 3) oscillatory burning leading to extinction, 4) reignition and 5) chuffing are predicted. The predicted dependence of frequency of L* -oscillations on mean pressure is compared with one set of available experimental data. It is found that proper modeling of the radiation heat flux from the chamber walls to the burning surface may be important to predict the re-ignition. In Chapter 8, the main conclusions of the present study are summarized. Certain suggestions for possible future studies to enhance the understanding of dynamic combustion of solid propellants are also given.

Engineering new solid propellant materials requires optimization of several factors, to include energy density, burn rate, sensitivity, and environmental impact. Equally important is the need for materials that will maintain their mechanical properties and thermal stability during long periods of storage. The nanoscale materials considered in this dissertation are proposed metal additives that may enhance energy density and improve combustion in a composite rocket motor. Density Functional Theory methods are used to determine cluster geometries, bond strengths, and energy densities. The ground-state geometries and electron affinities (EAs) for MnxO?: x = 3, 4, y = 1, 2 clusters were calculated with GGA, and estimates for the vertical detachment energies compare well with experimental results. It was found that the presence of oxygen influences the overall cluster moment and spin configuration, stabilizing ferrimagnetic and antiferromagnetic isomers. The calculated EAs range from 1.29-1.84 eV, which is considerably lower than the 3.0-5.0 eV EAs characteristic of current propellant oxidizers. Their use as solid propellant additives is limited. The structures and bonding of a range of Al-cyclopentadienyl cluster compounds were studied with multilayer quantum mechanics/molecular mechanics (QM:MM) methods. The organometallic Al-ligand bonds are generally 55-85 kcal/mol and are much stronger than Al-Al interactions. This suggests that thermal decomposition in these clusters will proceed via the loss of surface metal-ligand units. The energy density of the large clusters is calculated to be nearly 60% that of pure aluminum. These organometallic cluster systems may provide a route to extremely rapid Al combustion in solid rocket motors. Lastly, the properties of COOH-terminated passivating agents were modeled with the GPW method. It is confirmed that fluorinated polymers bind to both Al(111) and Al(100) at two Al surface sites. The oligomers HCOOH, CH3CH2COOH, and CF3CF2COOH chemisorb onto Al(111) with adsorption energies of 10-45 kcal/mol. The preferred contact angle for the organic chains is 65-85 degrees, and adsorption energy weakens slightly with increasing chain length. Despite their relatively weak adsorption energies, fluorinated polymers have elevated melting temperatures, making them good passivation materials for micron-scale Al fuel particles.

This thesis deals with the experimental and numerical analysis of the water hammer phenomenon generated by the discharge of a pressurized liquid into a pipeline kept under vacuum conditions. This flow configuration induces several multiphase phenomena such as cavitation and gas desorption that cannot be ignored in the water hammer behavior.<p><p>The motivation of this research work comes from the liquid propulsion systems used in spacecrafts, which can undergo fluid hammer effects threatening the system integrity. Fluid hammer can be particularly adverse during the priming phase, which involves the fast opening of an isolation valve to fill the system with liquid propellant. Due to the initial vacuum conditions in the pipeline system, the water hammer taking place during priming may involve multiphase phenomena, such as cavitation and desorption of a non-<p>condensable gas, which may affect the pressure surges produced in the lines. Even though this flow behavior is known, only few studies model the spacecraft hardware configuration, and a proper characterization of the two-phase flow is still missing. The creation of a reliable database and the physical understanding of the water hammer behavior in propulsion systems are mandatory to improve the physical models implemented in the numerical codes used to simulate this flow configuration.<p><p>For that purpose, an experimental facility modeling a spacecraft propulsion system has been designed, in which the physical phenomena taking place during priming are generated under controlled conditions in the laboratory using inert fluids. An extended experimental campaign was performed on the installation, aiming at analyzing the effect of various working parameters on the fluid hammer behavior, such as the initial pressure in the line, liquid saturation with the pressurant gas, liquid properties and pipe configuration. The influence of the desorbed gas during water hammer occurrence is found to have a great importance on the whole process, due to the added compressibility and lower speed of sound by an increasing amount of non-condensable gas in the liquid + gas mixture. This results in lower pressure levels and faster pressure peaks attenuation, compared to fluids without desorption. The two-phase flow was characterized by means of flow visualization of the liquid front at the location where the fluid hammer is generated. The front arrival was found to be preceded by a foamy mixture of liquid, vapor and non-condensable gas, and the pressure wave reflected at the tank may induce the liquid column separation at the bottom end. While column separation takes place, the successive pressure peaks are generated by the impact of the column back against the bottom end.<p><p>The resulting experimental database is then confronted to the predictions of the 1D numerical code EcosimPro/ESPSS used to assess the propulsion system designs. Simulations are performed with the flow configuration described before, modeling the experimental facility. The comparison of the numerical results against the experimental data shows that aspects such as speed of sound computation with a dissolved gas and friction modeling need to be improved. / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Les poudres propulsives pour armes sont des matériaux énergétiques dont la combustion permet l’accélération de projectiles jusqu’à des vitesses importantes. Ces matériaux énergétiques sensibles peuvent être soumis à de fortes contraintes (chocs, impacts et incendies) lors de leur utilisation. Le remplacement de certaines substances entrant dans leur formulation permet de diminuer leur vulnérabilité. En conséquence, ces poudres propulsives présentent une dynamique d’allumage différente. Ce travail de recherches est consacré à l’allumage des poudres propulsives pour armes et se présente en quatre chapitres. Un état de l’art sur le sujet est réalisé. Il porte en particulier sur la phénoménologie de l’allumage, la caractérisation de poudres propulsives, et la modélisation de l’allumage. Deux poudres propulsives sont expérimentalement analysées par thermogravimétrie, calorimétrie et spectrométrie de masse. Cette analyse permet de caractériser les différentes étapes cinétiques de la dégradation thermique de ces poudres propulsives. Un code de modélisation biphasique 2D est développé pour servir de support à la comparaison de modèles d’allumage. Le modèle implémenté décrit la chambre de combustion du canon dans les premières phases du coup de canon, lorsque le lit de poudre propulsive est compacté et que les gaz issus du dispositif pyrotechnique d’allumage le parcourent. Un modèle d’allumage est développé à partir des résultats expérimentaux obtenus au deuxième chapitre. Le code de calcul précédemment évoqué permet de comparer l’influence de différents modèles sur la propagation de l’allumage. / Gun Propellants are energetic materials whose combustion can accelerate projectiles to high speeds. These sensitive energetic materials can be subjected to high stresses (shocks, impacts and fires), potentially able to ignite them. The modification of their chemical formulation reduces such vulnerability. Consequently, these propellants have different ignition dynamics. This work focuses on the ignition of gun propellants and comes in four chapters. A state of the art on the subject is firstly made. It focuses on the phenomenology of the ignition and on energetic materials experimental characterization, and modeling of their ignition. Two gun propellants are experimentally analyzed by thermogravimetry, calorimetry and mass spectrometry. This analysis allows characterizing the various stages of the degradation kinetics of these propellants. A 2D biphasic modeling code was developed to provide support for the comparison of ignition models. It describes the combustion chamber in the early stages of the gun firing, when the propellant bed is compacted and the gases from the pyrotechnic igniter are flowing through it. An ignition model is developed from the experimental data obtained in the second chapter. The previously mentioned modeling code allows comparing the influence of different ignition models on the spreading speed of the ignition signal through the packed bed of propellant.