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RISS 인기검색어
- 검색키워드
- 저자 : Anirudha Ambekar (검색결과 6 건)
- 무료
- 기관 내 무료
- 유료
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Characterization of display pyrotechnic propellants: Colored light
Ambekar, Anirudha,Kim, Minsung,Yoh, Jack J. Pergamon 2017 Applied thermal engineering Vol. No.
<P><B>Abstract</B></P> <P>Pyrotechnic flames utilized as a source of illumination are typically characterized by the color and the luminous intensity of the flame. In the current study, five display pyrotechnic formulations utilized to produce colored flames have been investigated experimentally and theoretically. The experimental study was focused on photographically recording the colored flame of fireworks propellants burning at ambient conditions in order to quantify the flame color and the luminous intensity. This study reports the application of a digital single reflex camera as a colorimeter as well as a luminance meter. Theoretical estimation of the flame color was carried out by equilibrium thermochemical analysis followed by additive color mixing of the spectral emitters deduced to be present in the combustion products. The experimentally observed chromaticity and theoretical predictions were found to be reasonably close validating the methodology for the color prediction.</P>
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A reduced order model for prediction of the burning rates of multicomponent pyrotechnic propellants
Ambekar, Anirudha,Yoh, Jack J. Pergamon 2018 Applied thermal engineering Vol. No.
<P><B>Abstract</B></P> <P>This study reports a reduced order model for the prediction of the burning rate of pyrotechnic compositions. The combustion process of most pyrotechnics is primarily driven by condensed phase reactions. A priory estimation of the burning rate of pyrotechnics with multiple components may not be possible using the established methods. The study provides a simplified approach based on integral analysis of a proposed combustion wave structure for estimating the burning rate when the pyrotechnic composition, pure component thermo-physical properties, and thermo-kinetics parameter are known. The proposed combustion wave assumes a staged combustion process where the oxidizer undergoes decomposition in a broad reactive zone while fuel combustion occurs in a thin surface region. This approach takes account of the effective thermal conductivity as well as porosity of the pyrotechnic matrix. The pyrotechnic compositions studied here are expected to burn conductively at atmospheric pressure with little or no overpressure. The phenomenology of the combustion process of energetic materials is elucidated, and the reduced order model is validated through a case study.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Reduced order analytical model for burning rate of pyrotechnic compositions. </LI> <LI> Linear burning rate of multi-component granular porous pyrotechnics predicted. </LI> <LI> Conductive combustion regime with primary reactions occurring on the surface. </LI> <LI> Technique accounts for the propellant conductivity, heat of reaction, and porosity. </LI> <LI> Case study predictions for KClO<SUB>4</SUB> and KNO<SUB>3</SUB> based pyrotechnics reasonably accurate. </LI> </UL> </P>
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Characterization of display pyrotechnic propellants: Burning rate
Ambekar, Anirudha,Kim, Minsung,Lee, Woong-Hyun,Yoh, Jack J. Elsevier 2017 Applied thermal engineering Vol.121 No.-
<P><B>Abstract</B></P> <P>The combustion of display pyrotechnic propellants utilized for producing colored light has been studied. The linear burning rates of cylindrical propellant strands were measured using high-speed videography. The experiments were conducted with air at atmospheric pressure as the surrounding medium mimicking the conditions of unconfined aerial combustion typically encountered for these propellants. Five different formulations of display pyrotechnic propellants producing red, green, blue, yellow, and silver color were tested. The flame zone was observed to be situated very close to the propellant surface and the colored flame extended beyond this point. The phenomenology of the combustion process was explained and the combustion process was also studied numerically using a methodology based on the deflagration rate law. The experimentally measured burning rates were utilized in the deflagration rate law to obtain the simulation parameters which may be utilized in hydrocodes for performance prediction and simulation pyrotechnic propellant applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Combustion of display pyrotechnic propellants is studied. </LI> <LI> Linear burning rate of five propellant compositions evaluated in a strand burner. </LI> <LI> Numerical simulation was conducted using a deflagration rate law. </LI> <LI> Experimental burning rates were used to optimize deflagration rate law constants. </LI> </UL> </P>
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Ambekar, Anirudha,Yoh, Jack J. Elsevier 2019 Proceedings of the Combustion Institute Vol.37 No.3
<P>This study reports an experimental investigation into the chemical kinetics of several commercial pyrotechnic compositions. Differential Scanning Calorimetry (DSC) was utilized to elucidate the thermo-kinetic characteristics of four multicomponent pyrotechnic compositions. The combustion process of typical pyrotechnics is primarily driven by condensed phase reactions including processes such as phase change, decomposition, and oxidation. The multicomponent nature of practical pyrotechnics results in a particularly complex interaction between the components when heated. A thermo-kinetic study was performed to simulate the heating experienced by the pyrotechnics before the combustion zone. The physical processes occurring within these temperature limits provide important insight into the overall combustion rate. The non-isothermal DSC experimental technique combined with isoconversional methods, such as Friedman and Starink methods were utilized to evaluate the apparent chemical kinetics parameters for these propellants. The observations from the DSC study and isoconversional kinetic analysis provided an insight into the phenomenology of the combustion process of pyrotechnics. The problem of highly variable activation energy due to the presence of multiple reactions was addressed through a mechanistic deconvolution using nonlinear regression technique. The study confirmed the prominence of oxidizer decomposition on overall combustion reaction kinetics.</P>
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