Showing papers on "Burn rate (chemistry) published in 1975"

Behavior of Several Catalysts in the Combustion of Solid Propellant Sandwiches

Abstract: Theme T two-dimensional solid propellant sandwich has evolved as a convenient test vehicle for theories dealing with both physical and chemical behavior of composite solid propellant ingredients. It allows detailed observation of the binder-oxidizer interface over a range of test conditions. Sandwiches have been used by several investigators." Hightower and Price used laminated, two-dimensional sandwiches of single crystals of ammonium perchlorate and hydrocarbon binder. They considered this configuration to be "a compromise between the complexity of the three-dimensional 'combustion zone' and the naivety of a one-dimensional approximation." Jones investigated the catalytic behavior of Harshaw Catalyst, Cu 0202 and ferric oxide, Fe2O3 in solid propellant sandwiches of polycrystalline ammonium perchlorate (AP) and carboxyl terminated polybutadiene (CTPB). Hydroxyl terminated polybutadiene (HTPB) was substituted for CTPB and the behavior of the same catalysts over the pressure range 600-3200 psia was investigated. The sandwich vertical burn rate, the normal regression rate of the oxidizer and qualitative details of the deflagration process were obtained by cinephotomacrography. The current study has extended the investigation to include two additional catalysts,

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.

Role of Ferric Oxide Surface Area in Propellant Burn Rate Enhancement (First Step Toward Modeling)

Abstract: : Results of efforts to correlate composite propellant burn rate, ammonium perchlorate particle size distribution, and ferric oxide specific surface and level are presented. Results from laboratory-scale motor firings with HTPB- and CTPB-based propellants containing ferric oxides of 3 to 26.4 m squared/gm were used. The oxides had been prepared by precipitation and by calcination of either ferric sulfate or yellow iron oxide. Outcome of the analysis is a quantitative summarization of a mass of data showing how the several oxides perform in terms of their specific surface and level and as a function of oxidizer particle size distribution. Results indicate Fe2O3 specific surface is more significant at high fine-AP levels than at low fine-AP levels. Efforts to use the correlations in combustion modeling have barely begun. Catalysis probably takes place in the primary diffusion flame located at the AP-binder interface.

Audible and Ultrasonic Acoustic Emissions from Composite Solid Propellants.

Abstract: : The audible and ultrasonic acoustic emissions from deflagrating composite solid propellants were monitored and analyzed to evaluate their potential use as diagnostics of the combustion and as a means for the study of fundamental burning processes. A family of composite HTPB-AP propellants were tested which include a range of AP particle sizes, aluminized and nonaluminized formulations, the effect of the addition of a catalyst, and the presence of an AFCAM aluminum coating. For the audible emissions, the frequency behavior in the 0-10 kHz range can be explained by assuming the gas phase reaction time primarily controls the oscillating frequency. The combustion noise efficiency, cannot be explained by the theories put forth, so the physical makeup of the noise source is presently unknown. Analysis of the ultrasonic emission spectra indicates that there are no distinct spectral features which can be used to identify a particular propellant by its acoustic signature. The rms emission levels, however, can be used as a reliable, nonintrusive means for detecting flaws in the propellant, identifying bad burns, and measuring burn rates. The overall level increases with increasing burn rate and chamber pressure and decreasing particle size. (Author)

Synergistic Effects and Deflagration Analysis in Composite Solid Propellant Combustion

Abstract: : Using four common catalysts the existence and magnitude of synergistic effects upon burn rate are studied with HTPB-AP composite solid propellants. The effect under study is one whereby at a fixed total catalyst loading the mixture of two catalysts would be more effective in burn rate augmentation than a single catalyst. At 2000 psia all possible combinations of catalysts showed synergistic effects but the effects are weak and within the reproducibility range of the experiments. Ferric oxide and iron blue showed synergistic effects only at 300 and 2000 psia over the pressure range 300-2000 psia. Analysis of the effect of binder-oxidizer reactions upon the surface shape of a two-dimensional sandwich has shown that (a) the faster are these reactions the more deeply will the sandwich obtain a V-shape and b) these reactions are generally fast enough to indeed affect the surface shape.