Evaluation of Dynamic Burn Rate from the Extinction Compliance of Solid Rocket Motors
01 Mar 2007-Journal of Spacecraft and Rockets (American Institute of Aeronautics and Astronautics (AIAA))-Vol. 44, Iss: 2, pp 453-456
About: This article is published in Journal of Spacecraft and Rockets.The article was published on 2007-03-01. It has received 3 citations till now. The article focuses on the topics: Extinction (optical mineralogy) & Burn rate (chemistry).
Citations
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TL;DR: In this paper, the influence of surface orientation and attitude on the burn rate of a solid rocket motor was examined using a series of burning tests with different grain orientations, viz., vertical, inverted and horizontal.
Abstract: Experimental studies have been carried out using the in-house developed propellant samples at the atmospheric conditions to examine the influence of propellant surface orientation / attitude on burn rate. A series of burning tests are conducted with different grain orientations, viz., vertical, inverted and horizontal. We have observed 5 % burn rate augmentation on end-burning grains when the burning surface evolution was against the earth gravity compared to the normal vertical candle burning condition. We conjectured that the coupled effects of the instantaneous variations of the propellant burning surface attitude and the flight acceleration during the mission could alter the flame structure due to the local gravitational influence, which in turn alter the burn rate. This paper throws light for developing a suitable gravitational force dependant burn rate model for improving the performance prediction of solid rocket motors for aerospace applications.
2 citations
Cites background from "Evaluation of Dynamic Burn Rate fro..."
...Literature review reveals that the solid propellant burn rate modelling has developed to a point where it can and does make contributions to combustion research and practical propellant development [1-13]....
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19 Jan 2023
TL;DR: Kumar et al. as mentioned in this paper showed that relatively high and low viscosities are susceptible for flow choking in reacting flow systems, and the boundary layer blockage factor causing flow choking will be enhanced due to the significant flow turbulence.
Abstract: The decisive demonstration of the roots and aftermaths of the boundary layer persuaded flow choking (Sanal flow choking) and/or streamtube flow choking in non-reacting flows (V.R.S.Kumar et al., Physics of Fluids, 34(4), 2022, https://aip.scitation.org/doi/10.1063/5.0086638) and humans circulatory system (V.R.S.Kumar et al., Physics of Fluids, 34(10), 2022, https://aip.scitation.org/doi/10.1063/5.0105407) sheds lights on the diagnostic investigation of deflagration-to-detonation-transition (DDT) and asymptomatic explosions in internal and free external flows. An exact mathematical model derived from the compressible flow theory is reproduced herein to forecast the lower-critical-detonation-index (LCDI) in reacting flow systems (V.R.S.Kumar et al., Scientific Reports, 2021, https://www.nature.com/articles/s41598-021-94450-8). The closed-form analytical model reveals that comparatively high-viscosity and low heat capacity ratio of the leading species are prone to Sanal flow choking and/or streamtube flow choking in both internal and external flows. The three-dimensional (3D) and two-dimensional (2D) in silico reacting flow simulation results show that Sanal flow choking and sonic fluid throat effect assert the threshold condition of detonation and explosions. In silico studies further reveal that relatively high and low viscosities are susceptible for flow choking in reacting flow systems. The boundary layer blockage factor causing flow choking will be enhanced due to the significant flow turbulence because of high Reynolds number at a relatively low viscosity. We concluded that the undesirable shock wave followed by pressure-overshoot leading to detonation and/or explosion often observed in reacting flow systems due to Sanal flow choking and/or streamtube flow choking can be annulled judiciously by contravening the sonic fluid throat effect by retaining the total-to-static pressure ratio unceasingly lesser than the LCDI. The concept of sonic fluid throat effect reported herein reconfirms the Chapman–Jouguet (1899) condition of detonation propagation and ceases. In silico results presented herein ascertained that the theoretical discovery of Sanal flow choking and/or streamtube flow choking is a “paradigm shift” in predicting physics of detonation chemistry. Briefly, the theoretical discovery of the phenomenon of sonic fluid throat effect due to streamtube compression (pinching) in yocto to yotta scale reacting flow systems and beyond encompasses disruptive technologies at the cutting edge to elucidate century-long unanswered research questions in fundamental science and it further sheds light on exploring the basic cause(s) of detonation, environmental and supernova explosions.
1 citations
08 Jul 2007
References
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TL;DR: In this article, the authors reexamined the classical, linearized quasi-steady theory of unsteady combustion of homogeneous solid propellants (both pressure-and radiation-driven) and showed that it is physically impossible to obtain a zero Jacobian (δ or ns) parameter for pressure-driven combustion except perhaps in plateau regions.
52 citations
TL;DR: A microwave Doppler shift system, with increased resolution over earlier microwave techniques, was developed for measuring the regression rates of solid propellants during rapid pressure transients (104 to 10 5 IN cirr-sec) as mentioned in this paper.
Abstract: A microwave Doppler shift system, with increased resolution over earlier microwave techniques, was developed for measuring the regression rates of solid propellants during rapid pressure transients (104 to 10 5 IN cirr-sec). The system was used in two different transient combustion experiments: a rapid depressurization bomb and in the high-frequency acoustic pressure environment of a T-burner. In the rapid depressurization tests the measured apparent regression rates generally fell near or below the steady-state rate at the corresponding pressure and exhibited oscillations in tests near the critical depressurization rates for extinguishment. Unreasonably high oscillatory regression rates were obtained in the T-burner experiments. The results of a set of parameteric calculations indicated that flame ionization effects could be of sufficient magnitude to account for these anomalies. A direct comparison of the analytical predictions and experimental results yielded the conclusion that flame ionization effects probably produced some errors in the absolute values, but not the general characteristics, of the rapid depressurization regression rate measurements.
36 citations
TL;DR: In this paper, the results of a combined theoretical and experimental study of the process in which solid-propellant combustion is terminated by a rapid drop in pressure were presented. And the results were then compared to the predictions of the theoretical model that was based on the assumption that extinction occurs when the heat absorption by the solid propellant exceeds the heat transfer to the solid- propellant from the combustion gas.
Abstract: This paper presents the results of a combined theoretical and experimental study of the process in which solid-propellant combustion is terminated by a rapid drop in pressure. Experimentally, propellant burning in a small rocket motor was subjected to a rapid pressure drop when an auxiliary nozzle was suddenly opened. Such tests were run with varying nozzle sizes for the auxiliary nozzle, and the boundary between extinction and nonextinction was determined. The results were then compared to the predictions of the theoretical model that was based on the assumption that extinction occurs when the heat absorption by the solid propellant exceeds the heat transfer to the solid propellant from the combustion gas. In general, the theoretical predictions agreed well with both the experimental results gathered in this program and those published by other investigators.
26 citations
18 citations
TL;DR: In this article, a transient internal ballistics model was developed incorporating nonsteady continuity and energy equations for the chamber, non-steady energy equation for the propellant condensed phase, and a modified Zeldovich heat feedback function.
Abstract: Solid rocket performance during rapid pressure excursions differs greatly from predictions based on steady-state burning rate data. Rapid pressurization (150-250 kpsi/sec) following a sudden throat area decrease in a low L* combustor produces pressure overshoots of 10% and indicated burning rate overshoots in excess of 50%. A transient internal ballistics model was developed incorporating nonsteady continuity and energy equations for the chamber, nonsteady energy equation for the propellant condensed phase, and a modified Zeldovich heat feedback function for the propellant (which for the conditions considered is known to burn with a thin quasi-steady reaction zone). Sensitivity analyses using the model indicate that accurate surface temperature and temperature sensitivity data are needed. With reasonable estimates of surface reaction zone temperature and measurements of temperature sensitivity of burning rate, good agreement between the measured and the calculated p vs t was found for a nonmetallized composite propeliant in a low L* combustor. High pressure exponent, high temperature sensitivity of burning rate, high dAJdt, low burning rate, and low L* prominently increase the dynamic effects.
16 citations