Topic
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.
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01 Dec 2001
TL;DR: In this paper, the authors examined the physical meaning of dynamic vivacity and theoretically explored the behavior of dynamic volumetric surface area for conventionally ignited charges of various geometries, including layered propellant charges.
Abstract: : Historically, dynamic vivacity has been used extensively in propellant lot acceptance. More recently, dynamic vivacity has been used in the analysis of closed chamber experimental data to assess propellant grain surface area behavior during combustion. The objective of this report is to: (a) examine the physical meaning of dynamic vivacity; (b) theoretically explore the behavior of dynamic vivacity for conventionally ignited charges of various geometries, including layered propellant charges; and (c) determine the appropriate method for applying dynamic vivacity to electrothermal-chemical (ETC) closed chamber data. The results presented indicate that dynamic vivacity is a robust statistic for assessing grain surface area behavior during combustion as long as the burn rate exponent in Vielle's Law is between approximately 0.7 and 1.0. if the burn rate exponent is greater than 1.0, the nature of the propellant surface area deduced from the dynamic vivacity appears to be distorted. In these cases, the dynamic vivacity always indicates a progressive grain geometry. From the cases studied, it appears that grain fracture during combustion will not significantly change the dynamic vivacity results unless the original grain possess a progressive grain geometry and the fractured grain pieces are relatively large. Finally, it appears that ETC ignition does not impact the shape of the dynamic vivacity curve but only affects the magnitude of the curve.
14 citations
09 Jul 2006
14 citations
19 Oct 2014
TL;DR: In this article, the effects of combustion chamber geometry and wall conditions on thermal stratification and HCCI combustion were investigated in a single cylinder, gasoline-fueled, HCCIC engine.
Abstract: Thermal stratification of the unburned charge in the cylinder has a profound effect on the burn characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine. Experimental data was collected in a single cylinder, gasoline-fueled, HCCI engine in order to determine the effects of combustion chamber geometry and wall conditions on thermal stratification and HCCI combustion. The study includes a wall temperature sweep and variations of piston top surface material, piston top geometry, and compression ratio. The data is processed with a traditional heat release routine, as well as a post-processing tool termed the Thermal Stratification Analysis, which calculates an unburned temperature distribution from heat release. For all of the sweeps, the 50% burned point was kept constant by varying the intake temperature. Keeping the combustion phasing constant ensures the separation of the effects of combustion phasing from the effects of wall conditions alone on HCCI and thermal stratification.The results for the wall temperature sweep show no changes to the burn characteristics once the combustion phasing has been matched with intake temperature. This result suggests that the effects of wall temperature on HCCI are mostly during the gas-exchange portion of the cycle. The ceramic coatings were able to very slightly decrease the thermal width, increase the burn rate, increase the combustion efficiency, and decrease the cumulative heat loss. The combustion efficiency increased with the lower surface area to volume ratio piston and the lower compression ratio. Lastly, the compression ratio comparison showed a noticeable effect on the temperature distribution due to the effect of pressure on ignition delay, and the variation of TDC temperature required to match combustion phasing.Copyright © 2014 by ASME and General Motors
14 citations
TL;DR: In this article, the effect of various analytical methods on the nonlinear equation of the launching of a single-stage rocket with variable mass was investigated, including differential transformation method (DTM), homotopy perturbation method (HPM) and least square method (LSM).
14 citations
TL;DR: In this paper, composite solid propellant is prepared using tri-modal Ammonium perchlorate (AP) containing coarse, fine and ultrafine fractions of AP with average particle size (APS) 340, 40 and 5μm respectively, in various compositions and their rheological, mechanical and burn rate characteristics are evaluated.
14 citations