M. Rat

Bio: M. Rat is an academic researcher. The author has an hindex of 1, co-authored 1 publications receiving 12 citations.

Explosion thermique (cook off) des propergols solides

Abstract: Le document que nous presentons fait le point sur les premiers travaux effectues par le Centre de Recherches du Bouchet de la SNPE, sur les phenomenes d'explosion thermique, destines a etudier la stabilite des propergols solides. Ces travaux nous ont permis de mettre au point une methodologie d'essais pour mesurer assez precisement, les valeurs des constantes cinetiques et physiques des propergols et d'etablir, pour des blocs pleins et cylindriques de propergol composite aluminise, un modele empirique. Ce modele empirique (calque sur le modele theorique de Zinn et Mader(1) qui, experimentalement, ne s'adapte qu'aux explosifs) est susceptible de prevoir, a partir d'un nombre limite d'experiences, les temperatures critiques et les temps d'induction, quelle que soit la taille des blocs de propergol.

Development of Modern Solid Propellants

Abstract: ECAUSE of their relative simplicity, solid-propellant rockets came intouselongbeforeliquid-propellantrockets.Evenifthe initial uses of solid propellants in the form of blackpowder might have been in peaceful e reworks, history quickly mentioned them in connection with guns, e re arrows, and other types of armaments. This characteristic of being an “ old technology” and the connectionwith military devices probablypartially explains why, centuries later, thevisionariesofspacetraveltended to look to liquid systems, leavingthesolidrocketintheroleofanordnancedevice.Infacttheir strong orientation toward liquids was probably a consequence of a lack of vision of the future technology. And, in fact, during the e rst thousand years there was very limited progress in solid propellants, and this, of course, led to small hopes of achieving the high impulses of big rocket motors. The invention of composite propellants removed the impulse limitations in the middle of the 20th century. Ed Price 1 wrote that “ the history of solid rockets is very special for its spirit of people making things to happen.” We will see how the key people in the development of modern solid propellants had morethananyotherqualitythatofentrepreneurs.(Typicalexamples like the creation of Aerojet and the development of Thiokol will be describedlater.)Also,inmanyaspectsthepeopledealingwithsolids have often been inventors and self-made men, whereas the people involved in liquids were or considered themselves to be scientists and members of the academia. Of course, science always followed, butthischaracteristicofbeing asortofinvention,andsometimesthe characters of the inventors, might have contributed to some lower considerationforsolid-propellanttechnology,whichwassometimes considered a black art. Theinitialdevelopmentofcontemporarysolidpropellantsismore or less an American story, but the rest of the world followed, and some innovations in the technology came from outside the United States. Prehistory, inventions, inventors, science, technology, uses and applications, and development in the world should be covered inthispaper.Wehope thatthereaderwillexcuse theauthorforallof the imperfections and omissions: lack of information— mainly related to cone dentiality, either for security reasons or for proprietary reasons, extension of the task, limitation of space, loss of historical traces and archives, should be generally responsible. 2 Finally,it might be useful to remember a few points that are often forgotten by people not directly involved in solid-propellants technology and which justie es a high level of consideration for it. In a solid rocket

Energetic insensitive propellants for solid and ducted rockets

Abstract: After stating that propellants used on operational missiles do not yet meet all insensitive munition (IM) recommendations of the official French document, Instruction Nr 2060 DGA, IPE, characteristics of new formulations of composites and low-signature propellants are discussed. Butacene®, a prepolymer with grafted combustion catalyst species, reduces the sensitivity and reactivity of high-burning rate composite propellants when submitted to thermal hazards (or threats) without any loss of energetic performance in the operational temperature range. For minimum-smoke propellants, the use of energetic binders places limitations on both the amount of explosive fillers (nitramine) and the sensitivity of the energetic plasticizers to avoid the bore effect (with delayed shock-to-detonation transition phenomena) and losses in performance may have to be allowed. Other results obtained on extruded double-base propellants (SD 1175 and SD 1178), and gas-generator propellants show that it may be possible to design a motor that meets all the MIL-STD 2105 IM requirements. It is concluded that some progress is expected to be made in the near future using new energetic molecules such as hexanitrohexaazaisowurtzitane (CL-20), polyazidoglycidvie and hydrazinium nitroformate (mainly in minimum smoke propellant) to produce both high performance and high immunity levels.

Hydroxyl-terminated polymers obtained by free radical polymerization — Synthesis, characterization, and applications

Abstract: This article surveys methods and mechanisms of synthesis and characterization of hydroxytelechelic polymers by the free radical process. Some practical applications have been considered.

Cook-off test and numerical simulation of AP/HTPB composite solid propellant

Abstract: A small-scale cook-off experimental apparatus is designed to study the thermal security problem of ammonium perchlorate/hydroxyl-terminated polybutadiene (AP/HTPB) propellant. Both fast and slow cook-off tests are carried out. Then a cook-off model is established according to the apparatus, and compared with the experimental results. The theoretical calculation results are in good agreement with the experimental data. On this basis, the numerical predictions of cook-off properties of a solid rocket motor are performed at different heat fluxes. Results show that the initial cook-off response locations of AP/HTPB propellants all occur in the annular region on the outer wall of the propellant near the nozzle under the three kinds of heating flux conditions. The insulating effect of the insulating layer in the motor increases as the heat flux is increasing. When the heat flux is 10 3 W m −2 , 10 4 W m −2 and 10 5 W m −2 , the ignition delay time is 5071.5s, 348.5s and 41.0s, with the corresponding ignition temperature of 533.89 K, 554.97 K and 590.07 K, and the shell temperature of 521.38 K, 597.08 K and 837.92 K during the ignition near the nozzle. It can be concluded that the ignition delay time of the propellant is significantly shortened, and the ignition temperature as well as the shell temperature during the ignition near the nozzle increases gradually when the heat flux is increasing.

Three-Dimensional Simulation of Base Bleed Unit with AP/HTPB Propellant in Fast Cook-off Conditions

Abstract: In this work, a three-dimensional unsteady heat transfer model of base bleed unit with trilobite ammonium perchlorate (AP)/hydroxyl-terminated polybutadiene (HTPB) composite solid propellant is presented to analyze the cook-off characteristics. According to the two-step chemical reaction of AP/HTPB propellant, a small-scale cook-off test is established. A comparison of the experimental and calculated results is made to verify the rationality of the computation model. On this basis, a cook-off numerical simulation of the base bleed unit at the heating rates of 0.33, 0.58 and 0.83 K/s is presented to investigate the ignition and initiation characteristics. The results show that the ignitions occur on the head face of the AP/HTPB propellant and near the internal gas chamber in these conditions. As the heating rate increases, the runaway time decreases and the ignition temperature rises.