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.

The Combustion of HMX

Abstract: The burn rate of HMX was measured at high pressures (p more than 1000 psi). The self deflagration rate of HMX was determined from 1 atmosphere to 50,000 psi. The burning rate shows no significant slope breaks.

Measurements and ALE3D Simulations for Violence in a Scaled Thermal Explosion Experiment with LX-10 and AerMet 100 Steel

Abstract: We completed a Scaled Thermal Explosion Experiment (STEX) and performed ALE3D simulations for the HMX-based explosive, LX-10, confined in an AerMet 100 (iron-cobalt-nickel alloy) vessel. The explosive was heated at 1 C/h until cookoff at 182 C using a controlled temperature profile. During the explosion, the expansion of the tube and fragment velocities were measured with strain gauges, Photonic-Doppler-Velocimeters (PDVs), and micropower radar units. These results were combined to produce a single curve describing 15 cm of tube wall motion. A majority of the metal fragments were captured and cataloged. A fragment size distribution was constructed, and a typical fragment had a length scale of 2 cm. Based on these results, the explosion was considered to be a violent deflagration. ALE3D models for chemical, thermal, and mechanical behavior were developed for the heating and explosive processes. A four-step chemical kinetics model is employed for the HMX while a one-step model is used for the Viton. A pressure-dependent deflagration model is employed during the expansion. The mechanical behavior of the solid constituents is represented by a Steinberg-Guinan model while polynomial and gamma-law expressions are used for the equation of state of the solid and gas species, respectively. A gamma-law model is employed for the air in gaps, and a mixed material model is used for the interface between air and explosive. A Johnson-Cook model with an empirical rule for failure strain is used to describe fracture behavior. Parameters for the kinetics model were specified using measurements of the One-Dimensional-Time-to-Explosion (ODTX), while measurements for burn rate were employed to determine parameters in the burn front model. The ALE3D models provide good predictions for the thermal behavior and time to explosion, but the predicted wall expansion curve is higher than the measured curve. Possible contributions to this discrepancy include inaccuracies in the chemical models, integration of the momentum equation, and representation of the interfaces in the gaps. Two model problems were used to explore the effects of parameter variations on the fracture and fragmentation of AerMet 100 tube sections driven by the deflagration of LX-10. For the range of parameters considered, the model fragment sizes are of the same scale as the measured sizes.

Gas generation with high pressure sensitivity exponent propellant

Abstract: Gas generator apparatus usable with a ducted rocket propellant having a high exponent burn rate, a burn rate that is burn chamber pressure sensitive to a greater degree than are normally used propellants. The gas generator includes elementary pressure regulating elements and apparatus for damping movement of the pressure regulating elements to remove oscillatory components of motion therefrom. Burn rate operating point determination and the stability characteristics thereof are described along with the effects of variations in propellant burn rate exponent and regulating element parameters.

Castable double base propellants with compounds containing group IIA metal ions as ballistic modifers

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. It has been found that Group IIA metal salts, such as calcium carbonate and strontium carbonate, are capable of modifying the burn rate of propellants without resorting to lead as a burn rate additive. Accordingly, the use of from about 0.5% to about 5.0% Group IIA metal salt is taught as effective burn rate modifiers in propellants, in order provide non-toxic means for modifying the propellant burn rate.

Principle and Realizable Approach of Variable Burning Rate Propellant

Abstract: According to the interior ballistic performance of guns, a concept of variable-burning rate propellant was put forward, the fundamental principle of this propellant was discussed and the technologic way to realize the principle was explained.In order to realize the variable-burning rate ,the propellant has two layers ,inner layer's burning rate is higher than the outer layer's. The results show that two-layered variable-burning rate propellant has wishful discharge rule and good properties of progressive combustion.The propellant has the advantages of high energy,universal applicability and high security.