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.

Nozzleless rocket motor

Abstract: A solid rocket motor for accelerating a payload comprises a motor casing and a solid propellant matrix, utilizing a high burn-rate fuel. The use of a high burn rate fuel allows the rocket motor to operate in an end-burning fashion without the use of a constricting aperture to increase the back-pressure upon the burn-front of the fuel matrix. The exhaust gas produced from combustion of the propellant matrix exits directly to the ambient environment through a simple aperture without the use of an expansion nozzle. By eliminating the mass of the nozzle and allowing the use of lighter, less structurally robust motor casings, the needed acceleration of the vehicle can be achieved while using less propellant and a lighter launch vehicle.

Use of the nonlinear dynamical system theory to study cycle-to-cycle variations from spark ignition engine pressure data

Abstract: Cycle-to-cycle variations in the pressure evolution within the cylinder of a spark ignition engine has long been recognized as a phenomenon of considerable importance. In this work, use of tools borrowed to the nonlinear dynamical system theory to investigate the time evolution of the cylinder pressure is explored. By computing a divergence rate between different pressure cycles versus crank angle, four phases during the combustion cycle are exhibited. These four phases may be identified with the four common phases evidenced by burn rate calculations [1]. Starting from phase portraits and using Poincare sections, we also study correlations between peak pressures, IMEP and the durations from ignition to appearance of a flame kernel. Accounting for the fact that, during the ignition phase of the combustion cycle, trajectories in a plane projection of the reconstructed phase portrait associated with cycles in the case of motored engine cannot be distinguished from trajectories corresponding to combustion cycles, we estimate the duration of the ignition phase without any prior assumption on the combustion processes. Fluctuations of ignition phase lengths have been found to be correlated with IMEP standard deviations.

A Comparison of Barrel-Heating Processes for Granular and Stick Propellant Charges.

Abstract: : The natural flow channels offered by propelling charges composed of bundles of stick propellant significantly reduce the resistance to gas flow when compared to that of granular propellant charges, virtually eliminating potentially damaging pressure waves in the gun chamber. However, this same feature which reduces pressure waves may also result in more propellant remaining in the chamber, burning behind the origin of rifling, and perhaps increasing barrel erosion. In this study, a two-phase flow interior ballistic code (NOVA) is employed to compare propellant motion and heat transfer processes for ballistically-equivalent stick and granular propellant charges. A large difference in the motion of the solid phase during ignition and combustion is predicted for the two configurations, leading ultimately to an approximately 300 K higher maximum wall temperature for the stick propellant charge.