Modélisation du transfert thermique dans des propergols composites avec et sans particules d'aluminium

International audienceOn présente des méthodes et des résultats de modélisation sur le transfert thermique dans des échantillons de propergols composites à base de liant en polybutadiène (PBHT) et de particules de perchlorate d'ammonium (PA) et d'aluminium (Al). Le transfert de chaleur est simulé grâce à l'approche des volumes finis. On applique différentes méthodes de discrétisation des échantillons et plusieurs formulations pour la conductivité thermique moyenne dans le calcul des flux. On montre que le choix de la bonne méthode de modélisation est crucial pour une évaluation correcte de la conductivité thermique effective des échantillons

Ablation rate calculation of thermal insulations in segmented solid propellant rocket motors

Communication to : AIAA/SAE/ASME/ASEE 29th Joint Propulsion Conference and Exhibit, Monterey, CA (USA), June 28-30, 1993 ; published by AIAA (AIAA 93-1884)SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1993 n.131 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

High-order computation of burning propellant surface and simulation of fluid flow in solid rocket chamber

International audienceIn this paper, we present a numerical approach for predicting fluid flows in solid rocket motor (SRM) chambers. We use a novel high-order technique to track the burning grain surface. Spectral convergence toward the exact burning surface is achieved thanks to Fourier differentiation. In addition, we make use of a body-fitted mesh deforming with the burning surface and present a method to avoid manual remeshing. We describe several methods to deform the volume mesh and to keep good mesh element quality during the computation. We then couple the surface and volume approaches. The resulting coupled method is able to handle the formation of geometric singularities on the burning surface while keeping constant surface and volume mesh topology. This geometrical approach is integrated into a complex code for compressible, multi-species, turbulent flow simulations. Applications to the simulation of the internal flow in realistic solid rocket motors with complex grain geometry are then presented

Effects of convection errors on compressible turbulence simulations

Communication to : 1st AFOSR I.C. on DNS and LES, Ruston (USA), August 4-8, 1997SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1997 n.183 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Numerical simulation of the combustion of a single aluminium particle in air

Communication to : 5th international symposium on special topics in chemical propulsion, Stresa (Italie), June 18-22, 2000SIGLEAvailable from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2002 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Numerical simulations of vortex shedding phenomenon in a SRM using two approaches

Communication to : 32nd AIAA/ASME/SAE/ASEE joint propulsion conference, Lake Buena Vista, FL (USA), July 1-3, 1996SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.1996 n.163 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Numerical simulation of the combustion of a single aluminium droplet in propellant gas environment

Communication to : 2nd European conference on launcher technology, space solid propulsion, Rome (Italie), November 21-24, 2000Available from INIST (FR), Document Supply Service, under shelf-number : 22419, issue : a.2001 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

Détection des atomes de fer par spectrocopie d'émission et de fluorescence induite par laser en flammes de propergols solide.

International audiencePlanar laser-induced fluorescence on atomic iron is investigated in this paper, and a measurement strategy is proposed to monitor the fluorescence of iron atoms with good sensitivity. A model is proposed to fit the experimental fluorescence spectra, and good agreement is found between simulated and experimental spectra. Emission and laser-induced fluorescence measurements are performed in the flames of ammonium perchlorate composite propellants containing iron-based catalysts. A fluorescence signal from iron atoms after excitation at 248 nm is observed for the first time in propellant flames. Images of the spatial distribution of iron atoms are recorded in the flame in which turbulent structures are generated. Iron fluorescence is detected up to 1.0 MPa, which opens the way to application in propellant combustion.L'imagerie de fluorescence induite par laser est appliquée aux atomes de fer et une stratégie pour leurs mesurer avec une bonne sensibilité est présentée dans cet article. Un modèle est développé pour calculer les spectres de fluorescence et un bon accord est trouvé entre les spectres calculés et expérimentaux. Les mesures en émission et en fluorescence induite par laser sont effectuées dans des flammes de propergols composites à base de perchlorate d'ammonium dopés avec des catalyseurs ferriques.Le signal de fluorescence induit par l'excitation laser à 248 nm des atomes de fer est observé pour la première fois dans les flammes de propergol. La répartition spatiale des atomes de fer est visualisée en flamme dont les structures turbulentes sont forcées. La fluorescence du fer est détectée jusqu'à 1,0 MPa, ce qui ouvre des perspectives de visualisation d'écoulements de gaz de combustion de propergols solides

Numerical Simulation of 3D Unsteady Flowfield in Aft-Finocyl Solid Rocket Motor

The flowfield inside the second solid stage of the European launch vehicle VEGA is simulated with a full 3D unsteady flow solver in order to characterize the unsteadinesses, aero-acoustics and dynamics loads resulting from the growth of complex vorticity patterns in the internal flow of the aft-finocyl solid rocket motor. The analysis considers different configurations during the firing of the solid stage: the first one corresponds to an advanced stage of combustion, when the aft-part of the propellant grain is almost completely burnt out and the aft-end cavity is almost empty of propellant; the second one corresponds to an early stage of combustion, with a large burning surface and a small internal volume available for the flow. The first configuration is computed for different motor geometrical conditions: a symmetric case, a case with an imposed small angle of nozzle gimbaling and a case with an imposed propellant grain offset with respect to motor assembly. The second configuration is analyzed considering a small angle of nozzle gimbaling. The rotation of the gimbaled nozzle, as well as the propellant grain offset are imposed in such a way to remove any symmetry in the motor geometry. The motor configuration advanced into the firing shows the presence of low-level limit cycle oscillations of the flowfield at high frequency, resulting into the generation of lateral force oscillations of the order of one percentage of the generated thrust. This peculiar behavior is not altered by the perturbation of the motor geometry due to the imposed nozzle gimbaling; whereas it is slightly modified in terms of lower characteristic frequencies and lower amplitude of the oscillations, for the case with the imposed propellant grain offset. The presence of such flowfield fluctuations is caused by the onset of unstable sound generating vortical structures along the motor axis, that produce pressure fluctuations and that are coupled with acoustic waves. The motor configuration early into the firing, instead, does not show any significant of flow instability