Showing papers on "Burn rate (chemistry) published in 1980"

Review of Composite Propellant Burn Rate Modeling

Abstract: Steady-state combustion modeling of composite solid propellants is discussed with emphasis on the Beckstead-Derr-Price (BDP) model The BDP model and some revisions are considered with respect to the analysis of monomodal ammonium perchlorate/inert binder propellants: topics examined include continuity relations, surface area relations, characteristic surface dimension, flame heights, and energy balance Application of the BDP model to more complicated propellants containing multiple active ingredients is described These propellants include multimodal, mixed oxidizer, active binder, aluminized, catalyzed, and nitramine propellants Example cases of modeling (with comparison to experimental data) are presented, and strengths and weaknesses of current modeling approaches are evaluated

Model for double-base propellant combustion

Abstract: The Beckstead-Derr-Price (BDP) monopropellant model that was originally developed as a limiting case for composite propellants has been modified and applied to double-base propellants. The work was performed with the intent of applying the model to modern double-base systems of interest in rocket propulsion. Therefore, the model has been developed to predict burn rate as a function of pressure, initial temperature, and the double-base binder energy. The model has been compared to a set of experimental data covering a wide range of pressures, initial temperatures, and binder energy with excellent agreement. A comparison with 81 test conditions resulted in 96% of the predictions within ± 10% of the data and a maximum error of 12%. All of the calculated rates, sensitivities, and combustion parameters using the double-base model appear to be consistent with available experimental data. The quantitative predictions of the model varying pressure, initial temperature, and binder energy are considered a significant advance in the state of the art.

Use of Closed Vessel as a Constant Pressure Apparatus for the Measurement of the Rate of Burning of Propellants

Abstract: A method for the determination of burning rates of propellants whose from function is unknown is introduced. The method consists of burning in the closed vessel, a known charge weight of the test propellant alongwith a known pressure which remains nearly constant during the burning of the test propellant whose web size is the only quantity required for the evaluation of its rate of burning. The test propellants burns at near constant pressure conditions just as in the strand burner technique. This method can be applied to any unknown propellant of any shape whose web size can be measured and very large webs also can be used. In addition, the measurement of the records and the computation are very simple.

Effect of HMX on the combustion response function

Abstract: Over a pressure range of 3.5-7 MPa and a frequency range of 500-2000 Hz and compared to propellants having equivalent energy and burn rate, HMX produces less pressure-coupled acoustic driving than AP and is equivalent to NC/TMETN. Formation of carbonaceous combustion products indicates that binder decomposition does not follow equilibrium thermochemistry, and that this is aggravated by fuel richness or the absence of AP.

Modular instrumentation system for real-time measurements and control on reciprocating engines

Abstract: An instrumentation system was developed for reciprocating engines. Among the parameters measured are the indicated mean effective pressure, or theoretical work per cycle, and the mass fraction burn rate, a measure of the combustion rate in the cylinder. These computations are performed from measured cylinder pressure and crankshaft angle and are available in real time for the experimenter. A 100 or 200 consecutive-cycle sample is analyzed to reduce the effect of cyclic variations in the engine. Data are displayed in bargraph form, and the mean and standard deviation are computed. Other instruments are also described.

Analytical Model of High-pressure Burning Rates in a Transient Environment

Abstract: A transient ballistics and combustion model is derived to represent the closed vessel experiment that is widely used to characterize the high pressure burning rates of solid propellants. The model is applied to explain why burning rates deduced from the closed vessel are in basic agreement with those measured from an equilibrium strand burner in the case of homogeneous propellants, but differ significantly in the case of nitramine composite propellants. Thermal profile time lag effects become small at high pressure because the burning rates become high. However, the development of the burning surface structure of those nitramine propellants which exhibit shifts in pressure exponent causes the mass burning rate to lag and then exceed the equilibrium value. It is necessary to consider this mechanism in applications dealing with high pressures and pressurization rates.

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.

Dynamic Burning Effects in the Combustion of Solid Propellants with Cracks, and the Use of Granular Bed Combustion Models

Abstract: : This report is a facsimile of a report submitted by Systems Associates, Pennsylvania State University, under Contract N60530-79C-0006 and maintains the original format. It includes the study of dynamic burning effects in the combustion of solid propellants with cracks, and the use of granular bed combustion codes for solving hazard problems in rocket propulsion systems. The Zeldovich quasi-steady flame model was used in the evaluation of the dynamic burning effect. The dynamic burning rate was obtained by solving the transient heat conduction equation for the solid propellant and using the Zeldovich map for determining the heat feedback. Results indicate a stronger dynamic burning response for a higher pressurization rate, larger energy storage in the propellant, and lower initial pressure. A dynamic burning-rate augmentation function was developed to facilitate the incorporation of the transient burning effect into the crack combustion code. The augmentation function is in close correlation with results obtained from the finite difference method over the broad range of conditions studied. The mobile and fixed granular bed combustion codes (MGBC and FGBC), users manuals for these two programs, sample input data, and output listing were delivered to NWC.