Burn rate (chemistry)

About: Burn rate (chemistry) is a research topic. Over the lifetime, 847 publications have been published within this topic receiving 8908 citations. The topic is also known as: Burning rate.

Smokeless GAP-RDX Composite Rocket Propellants Containing Diaminodinitroethylene (FOX-7)

Abstract: Composite rocket propellants prepared from nitramine fillers (RDX or HMX), glycidyl azide polymer (GAP) binder and energetic plasticizers are potential substitutes for smokeless double-base propellants in some rocket motors. In this work, we report GAP-RDX propellants, wherein the nitramine filler has been partly or wholly replaced by 1,1-diamino-2,2-dinitroethylene (FOX-7). These smokeless propellants, containing 60% energetic solids and 15% N-butyl-2-nitratoethylnitramine (BuNENA) energetic plasticizer, exhibited markedly reduced shock sensitivity with increasing content of FOX-7. Conversely, addition of FOX-7 reduced the thermochemical performance of the propellants, and samples without nitramine underwent unsteady combustion at lower pressures (no burn rate catalyst was added). The mechanical characteristics were quite modest for all propellant samples, and binder-filler interactions improved slightly with increasing content of FOX-7. Overall, FOX-7 remains an attractive, but less than ideal, substitute for nitramines in smokeless GAP propellants.

Development of erosive burning models for cfd predictions of solid rocket motor internal environments

Abstract: Four erosive burning models, equations (11) to (14). are developed in this work by using a power law relationship to correlate (1) the erosive burning ratio and the local velocity gradient at propellant surfaces; (2) the erosive burning ratio and the velocity gradient divided by centerline velocity; (3) the erosive burning difference and the local velocity gradient at propellant surfaces; and (4) the erosive burning difference and the velocity gradient divided by centerline velocity. These models depend on the local velocity gradient at the propellant surface (or the velocity gradient divided by centerline velocity) only and, unlike other empirical models, are independent of the motor size. It was argued that, since the erosive burning is a local phenomenon occurring near the surface of the solid propellant, the erosive burning ratio should be independent of the bore diameter if it is correlated with some local flow parameters such as the velocity gradient at the propellant surface. This seems to be true considering the good results obtained by applying these models, which are developed from the small size 5 inch CP tandem motor testing, to CFD simulations of much bigger motors.

Burn rate modification of solid propellants with bismuth trioxide

Abstract: Propellant formulations are provided which include non-toxic burn rate modifiers. In order to produce a usable propellant formulation, it is necessary to control the burn rate of the propellant. Failure to adequately control the propellant burn rate often results in unacceptable performance of the propellant. For example, during the operation of a rocket motor, or similar device which contains a propellant, the propellant may produce operating pressures which are too high or too low for the intended purpose of the device. It has often been the practice to add lead to rocket motor propellants in order to modify the burn rate and to maintain the burn rate within acceptable parameters. Lead, however, is known to be toxic and a pollutant. Accordingly, it is desirable to replace the lead in the formulation. It has been found herein that bismuth trioxide is capable of modifying the burn rate of propellants without resorting to lead as a burn rate additive. Accordingly, the use of bismuth trioxide is taught as effective burn rate modifiers in propellants, in order provide non-toxic means for modifying the propellant burn rate.

Method for control of subsurface coal gasification

Abstract: The burn front in an in situ underground coal gasification operation is controlled by utilizing at least two parallel groups of vertical bore holes disposed in the coalbed at spaced-apart locations in planes orthogonal to the plane of maximum permeability in the coalbed. The combustion of the coal is initiated in the coalbed adjacent to one group of the bore holes to establish a combustion zone extending across the group while the pressure of the combustion supporting gas mixture and/or the combustion products is regulated at each well head by valving to control the burn rate and maintain a uniform propagation of the burn front between the spaced-apart hole groups to gasify virtually all the coal lying therebetween.