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.

Numerical Study of Erosive Burning in Multidimensional Solid Propellant Modeling

Abstract: Using numerical simulations, the combustion response of heterogeneous solid propellants to an imposed crossflow velocity field are examined. It is shown that this model flow is useful to capture the influence of shear flow in the so-called erosive burning phenomenon observed in actual experiments. Previous numerical studies on a model quarter-plane problem and on homogeneous solid propellants have shown that the presence of shear in the crossflow plays a role in increasing the heat transfer to the propellant surface, thus enhancing the burn rate. In the current work, the response of twoand three-dimensional packs to an imposed velocity field are first examined for different propellant morphologies and at different pressures. The imposed velocity field has its root in a separate nonreactive multiscale analysis. It is shown that, with the model flow, the variations of the erosive burning rate with shear parameters are captured, the trends being in line with experimental results. Furthermore, a comparison with experimental results present in the literature is examined, where it is shown that the results compare qualitatively well with the experiments using the estimated shear rates from the experiment. These results suggest that the influence of the shear flow on the primary diffusion flame may be a leading factor in the erosive burning effect.

Some Problems in the Unsteady Burning of Solid Propellants

Abstract: : The model of uniformly distributed combustion in the gas phase is used as the basis for examining several features of unsteady burning. As a zeroth approximation the flame zone begins at the solid-gas interface and responds linearly and quasi-statistically to changes of pressure only. Three deviations from this behavior are then examined: the combustion zone is displaced from the surface, the energy release responds to fluctuations of temperature and the response is not quasi-static. It appears that the assumption that the burning begins immediately at the surface can lead to significant changes, more important than the assumption that the energy release responds to changes of pressure only, especially in the interpretation of experimental data. The problem of nonquasi-static behavior, i.e., processes in the gas phase do not follow precisely impressed changes of pressure, is formulated as an expansion in frequency. Approximate results seem to be consistent with existing information.

Effect of Protrusion in the Enhancement of Regression Rate in Hybrid Rocket

Abstract: It has been reported in literature that the use of protrusion in the combustion chamber of a hybrid rocket motor enhances the regression rate. This study reports careful experiments conducted to show that the improvement in burn rate with protrusions is only up to a certain fraction of the overall burn time. From the results obtained, it is seen that an X/L of 0.5 is the best location for a graphite protrusion. The protrusions are also shown to increase the combustion eciency by as much as 45 % when placed at an X/L of 0.5. This, more than the improvement in the regression rate is very useful, especially for small scale motors whose combustion eciencies are otherwise very low.