Burning rate definition

The prediction of burning-rate characteristics, on the other hand, has not been possible. This has caused rocket designers to adopt a trial-and-error approach to the development of specific propellants to meet specific mission requirements. In an effort to reduce the large development effort required for each new propulsion system, considerable basic research effort has been directed toward the definition and quantitative characterization of propellant combustion mechanisms. The ultimate objective of this effort is to provide methods for predicting the burning-rate characteristics of particular propellant formulations. 

The change of burning rate by the change of initial propellant temperature changes the equilibrium pressure pc in a rocket motor. Thus, one needs to introduce the temperature sensitivity of pressure in the combustion chamber,, similar to the definition of op ... 

The NFPA 430 classification system, the fire hazard behavior of liquid and solid oxidizers that can increase the burning rate or cause spontaneous ignition of a combustible material. Also, the reactivity behavior of liquid and solid oxidizers includes those that can undergo a self-sustained decomposition or an explosive reaction. The definitions used to define liquid and solid oxidizer classes can be subject to interpretation. The NFPA 430 classification system is based on the Technical Committee s evaluation of available scientific and technical data, actual experience, and it s considered opinion. A listing of typical liquid and solid oxidizers by class can be found in the Appendix of NFPA 430. The oxidizers listed are assumed to be pure materials unless otherwise specified. 

Figures (see Table 8.1) were given for the neutron activity of the plutonium obtained from the different plants. The first figure given for the Windscale piles is the burn up in the reactor, which could be expressed as a percentage — 5% of the atoms have been burned up . This is not easy to measure, so an alternative definition is used, which is the amount of thermal energy produced per ton (or tonne) of fissile material. Thus 200 MWD is 200 megawatt days, equivalent to 200 X 10 W x86,400 s = 1.7 x 10 J. By modern standards, these burn rates are very low. A 1% burn up is very approximately equal to 10,000 MWD/T.

Some chemicals can react with themselves or with other chemicals to burn or explode to release their chemical energy. The distinction between burning or exploding depends on the rate of reaction according to the following definitions ... 

Although a laminar flame speed. S L is a physicochemical and chemical kinetic property of the unbumed gas mixture that can be assigned, a turbulent flame speed. S T is, in reality, a mass consumption rate per unit area divided by the unbumed gas mixture density. Thus,. S r must depend on the properties of the turbulent field in which it exists and the method by which the flame is stabilized. Of course, difficulty arises with this definition of. S T because the time-averaged turbulent flame is bushy (thick) and there is a large difference between the area on the unbumed gas side of the flame and that on the burned gas side. Nevertheless, many experimental data points are reported as. S T. 

Following the conclusions of Bowman [1], then, from the definition of prompt NO, these sources of prompt NO in hydrocarbon fuel combustion can be identified (1) nonequilibrium O and OH concentrations in the reaction zone and burned gas, which accelerate the rate of the thermal NO mechanism (2) a reaction sequence, shown in Fig. 8.7, that is initiated by reactions of hydrocarbon radicals, present in and near the reaction zone, with molecular nitrogen... 

Fig. 6.21 Definition of super-rate, plateau, and mesa burnings of a catalyzed double-base propellant.

A kinetic analysis of the results, based on (17) and its O+OH analog, is in satisfactory agreement with observations on a wide variety of flames. These flames are relatively cool, and the concentrations of H and OH exceed their equilibrium values even in the burned gases, so that the observed sodium emission is definitely chemiluminescent. The third order rate coefficients for excitation by H+H and H+OH are estimated to be 8 x 109 and 2x 1010 l2.mole-2.sec-1, corresponding to an efficiency near unity per triple collision. The possible importance of mechanisms of the type (14,15) has not been carefully studied. 

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