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.

Electrical Control of Solid Propellant Burning

Abstract: The possibility of varying at will the rate of burning of solid propellants, after ignition, by the use of electric fields, is considered. Two methods seem possible; varying the normal burning rate and varying the rate of flame spread over surfaces. The latter, which can be used to control the total consumption rate by varying the rate at which ‘internal area’ can be opened up, is shown to be by far the most promising. Ionic winds can be used to increase it by making the propellant one electrode, or decrease it by using an electrode contacting the flame, in an enclosed system, so as to maintain the propellant surface cool by a flow of entrained air. In simple systems at atmospheric pressure increases of about 200 fold and decreases of approx. 10 fold, with respect to the unperturbed value, are achieved. Theory indicates that larger effects should be possible at the higher pressures relevant to combustion in rockets.

Measurement of Steady State and Transient Solid Propellant Burning Rates with Microwaves.

Abstract: : A microwave continuous measurement technique has been utilized to measure burning rates of a CTPB and AP composite solid propellant during steady state and rapid decompression. A microwave signal oscillating at a known source frequency is passed through the end of a burning propellant strand opposite the burning surface and allowed to reflect off the burning surface which is receding at some unknown velocity. By continuously comparing the phse angle of this reflected signal with the phase angle of another signal oscillating at the original source frequency, a relative phase angle between the two signals is obtained. The rate of change of this relative phase angle with time is proportional to the propellant's burning rate. Accurate (plus or minus 10 percent) continuous burning rate data was obtained and shown to be within capabilities of the system for dP/dt values less than about 2500 psi/second. (Modified author abstract)

Low burn rate motor propellant

Abstract: A low burn rate motor propellant containing hydroxyl terminated polybutade, HMX and hexanedioldimerate polymer.

Cycle-By-Cycle Variation in Spark Ignition Internal Combustion Engines

Abstract: : The primary objective of this work was to extend the engine cycle simulation used by the Oxford Internal Combustion Engine Group to enable it to perform cycle-by-cycle modelling. A literature review concluded that the most appropriate metric for quantifying the cyclic variation was the coefficient of variation of the indicated mean effective pressure, and that for zero dimensional computer simulations, the most sensible parameter to perturb for cycle-by-cycle modelling was the burn rate. Modelling attempts using burn rate information alone resulted in an under-prediction of the cyclic variability exhibited by the engine. The work then examined a two-zone polytropic process model in an attempt to improve burn rate estimation. The model proved unreliable for burn rate calculations. The Rassweiler and Withrow method was then modified to include both the compression and expansion indices throughout the combustion period. The technique proved viable, but was not used because the slow burn up of the significant crevice mass in the experimental engine made calculation of an accurate expansion index doubtful. A further cause of the under-prediction in cyclic variability was postulated to be incomplete combustion, which is not detected by the burn rate model. A completeness of combustion parameter was derived from information contained in the Rassweiler and Withrow analysis. This parameter was used along with burn rate variations to perturb the cycle simulation and resulted in good cycle-by-cycle agreement between the experimental data and the modelled data in terms of mean effective pressure, maximum pressure, and the phasing of maximum pressure. Cyclic measurements of NO showed that the technique did not predict the cyclic variability in NO formation, and this was attributed to the sensitivity of NO formation to parameters that were not allowed to vary on a cyclic basis within the model (such as residuals).