• Fire Science and Engineering
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• v.23 no.1
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• pp.33-39
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• 2009

In this study, the combustion properties, which are called the reaction-to-fire's performance, of sandwich panels were tested and analyzed according to both ISO 5660 (cone calorimeter method) and EN 13823 (SBI). Several variables including ignition time, mass loss, heat release rate, smoke production rate and $O_2$ density about four sandwich panels and four core materials (thermal insulation material) were evaluated. Combustion properties' similarity and difference of sandwich panels and core materials were compared by materials and test methods respectively. Finally test results were evaluated by Japanese standard building code, National Building code of Canada and EN 13501-1 as well.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.128-135
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• 2007

Combustion characteristics of full-scale gas generators were studied experimentally by changing the injector number installed at the injector head. Three full-scale gas generators were utilized; they have same total mass flow rate but mass flow rates per injector are different. Thirteen, nineteen and thirty seven injectors, which have internal-mixing and double-swirl characteristics, are distributed in injector heads, respectively. The results showed that pressure fluctuations in the gas generators with 13 and 19 injectors didn't occur around longitudinal resonant frequency, however longitudinal-mode pressure fluctuation appeared slightly in the gas generator with 37 injectors. As the number of injectors increased, deviations of temperature distribution in the combustion chamber decreased gradually, but the damage of injector LOx posts became a little severe.

• Journal of the Korean Society of Combustion
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• v.19 no.4
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• pp.14-20
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• 2014

In the present study, an annular combustor for a 500 W class micro gas turbine generator was designed and its characteristics were investigated by using both numerical and experimental methods. For this purpose, geometrical configurations of the annular combustor were determined in the aspect of the aerodynamic and chemical consideration. Also, fluid flow and pressure drop characteristics in the combustor were numerically studied by using commercial tool, FLUENT. Based on the numerical results, the diameter and the angle of air admission holes in the primary zone were chosen to be 2.5 mm and $30^{\circ}$, respectively. Finally, an integrated test unit, which consisted of a compressor, combustor, turbine, and motor/generator, was developed in order to measure the combustor efficiency. As the temperature difference between the combustor inlet and the turbine inlet or the air mass flow rate increased, the combustor efficiency increased and it was over 90% when the air mass flow rate was larger than 7.30 g/s. It was shown that the annular combustor developed in this study met the design requirement for a 500 W class micro gas turbine generator.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.696-701
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• 2018

The nitrogen oxides generated during combustion reactions have a great influence on the generation of acid rain and fine dust. As an NOx reduction method, exhaust gas recirculation combustion using Coanda nozzles capable of recirculating a large amount of exhaust gas with a small amount of air has recently been utilized. In this study, for the burner outlet with dual end opening, the use of a recirculation burner was investigated for the distribution of the pressure, streamline, temperature, combustion reaction rate and nitrogen oxides using computational fluid analysis. The gas mixed with the combustion air and the recirculated exhaust gas flow in the tangential direction of the circular cylinder burner, so that there is a region with low pressure in the vicinity of the fuel nozzle exit. As a result, a reverse flow is formed in the central portion of the burner near the center of the circular cylinder burner and the exhaust gas is discharged to the outside region of the circular cylinder burner. The combustion reaction occurs on the right side of the burner and the temperature and NOx distribution are relatively higher than those on the left side of the burner. It was found that the average NOx production decreased from an air flow ratio of 1.0 to 1.5. When the air flow ratio is 1.8, the NOx production increases abruptly. It is considered that the NOx production reaction increases exponentially with temperature when the air ratio is more than 1.5 and the NOx production reaction rate increases rapidly on the right-hand side of the burner.

• Fire Science and Engineering
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• v.30 no.4
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• pp.65-72
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• 2016

This study examined the generation of combustion toxic gases of pinus rigida specimens processed with bis-(dimethylaminomethyl) phosphinic acid (DMDAP), bis-(diethylaminomethyl) phosphinic acid (DEDAP), and bis-(dibutylaminomethyl) phosphinic acid (DBDAP). Each pinus rigida plate was coated three times with 15 wt.% flame retardants in an aqueous solution. The specimens were then dried at room temperature. The production of combustion toxic gases was investigated using a cone calorimeter (ISO 5660-1). The first time to peak mass loss rate ($1^{st}-TMLR_{peak}$) processed with the chemical additives decreased to 5.9 from 41.2% compared with the unprocessed specimen. The second time to the peak mass loss rate ($2^{nd}-TMLR_{peak}$) for the processed specimens was decreased 1.8% for DMDAP and 5.3% for DBDAP and increased 1.8% for DEDAP. The peak carbon monoxide ($CO_{peak}$) production was 1.5 to 2.0 times higher than that of the unprocessed plate. The peak carbon dioxide ($CO_{2peak}$) production was reduced 0.01 times for DMDAP and increased 1.15 to 1.19 times for DEDAP and DBDAP compared with the unprocessed specimens. In particular, the oxygen concentration was much higher than 15%, which can be fatal to humans and the resulting hazard can be eliminated. Overall, the combustion toxicity of flammable gas were increased partially by the chemical additives compared with those of the unprocessed plate.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.258-261
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• 2003

The optimal design and combustion analysis of the gas generator for Liquid Rocket Engine (LRE) were performed. A fuel-rich gas generator in open cycle turbopump system was designed for 101on1 in thrust with RP-1/LOx combination. The optimal design was done for maximizing specific impulse of main combustion chamber with constraints of combustion temperature and power matching in turbopump system. Results of optimal design show the dimension of length, diameter, and contraction ratio of gas generator. The configuration of the gas generator and the condition for performance which can maximize the objective function were determined and found to meet the design constraints. Also, the combustion analysis was conducted to evaluate the performance of designed chamber and injector of gas generator. And the effect of the turbulence ring was investigated on the mixing enhancement in the chamber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1121-1126
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• 2010

This study is to investigate the effects of aromatics and T90 for low cetane number (CN) fuels on combustion and exhaust emissions in low-temperature diesel combustion. We use a 1.9-L common rail direct injection diesel engine at 1500 rpm and 2.6 bar BMEP. Low temperature diesel combustion was achieved via a high external EGR rate and strategic injection control. The tested fuels four sets: the aromatic content was 20% (A20) or 45% (A45) and the T90 temperature was $270^{\circ}C$ (T270) or $340^{\circ}C$ (T340) with CN 30. Given the engine operating conditions, the T90 was the stronger factor on the ignition delay time, resulting in a longer ignition delay time for higher T90 fuels. All the fuels produced nearly zero PM because of the extension of the ignition delay time induced by the low cetane number. The aromatic content was the main factor that affected the NOx and the NOx increased with the aromatic content.

• Applied Chemistry for Engineering
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• v.27 no.1
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• pp.39-44
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• 2016

This study was to investigate the characteristics of combustion toxic gases of pinus rigida specimens treated with chemical additives such as pyrophosphoric acid (PP)/ammonuium ion ($NH_4{^+}$), methylenepiperazinomethyl-bis-phosphonic acid (PIPEABP) and $PIPEABP/NH_4{^+}$. Each pinus rigida plates was painted in three times with 15 wt% of each chemical additives in the aqueous solution. After drying these specimens at room temperature, the production of combustion gases and smoke was examined by the cone calorimeter (ISO 5660-1). As a result, the peak mass loss rate time (PMLR time) treated with chemicals was delayed upto 10.5~47.4% compared to that of using untreated specimen. In addition, the peak production of carbon monoxide ($CO\;_{peak}$) of 32.1~71.4% and total smoke release rate (TSRR) of 15.6~43.6% for test pieces treated with the chemical additive were higher than that of using the virgin plate. In particular, for the specimens treated with the chemical additive, the rate of smoke release (RSR) 29.4~41.5% was obtained higher than that of untreated plate except the specimen treated with $PP/4NH_4{^+}$. It can thus be concluded that the treatment using the chemical additive could partially increase the combustion-retardation properties of the species when compared to those of the virgin plate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.11
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• pp.2150-2158
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• 1992

This study was carried out to investigate the flow structure and mixing process of a cross mixing flow formed by two round jets with respect to the ratio of mass flow rate. This flow configuration is of great practical relevance in a variety of combustion systems, and the flow behaviour of a cross jet defends critically on the ratio of mass flow rate and the cross angle. The mass flow rate ratios of two different jets were controlled as 1.0, 0.8, 0.6, and 0.4, and the crossing angle of two round jets was fixed at 45 degree. The velocities issuing from jet nozzle with an exit diameter of 20mm were adjusted to 40m/s, 32m/s, 24m/s, and 16m/s, and the measurements have been conducted in the streamwise range of $1.1X_0$to $2.5X_0$ by an on-line measurement system consisted of a constant temperature type two channel hot-wire anemometry connected to a computer analyzing system. The original air flow was generated by a subsonic wind tunnel with reliable stabilities and uniform flows in the test section. For the analysis of the cross mixing flow structure in the downstream region after the cross point, the mean velocity profiles, the resultant velocity contours, and the three-dimensional profiles depending upon the mass flow rate ratio have been concentrately studied.

• Advances in aircraft and spacecraft science
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• v.4 no.3
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• pp.281-296
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• 2017

The axial-injection end-burning hybrid rocket proposed twenty years ago by the authors recently recaptured the attention of researchers for its virtues such as no ${\zeta}$ (oxidizer to fuel mass ratio) shift during firing and good throttling characteristics. This paper is the first report verifying these virtues using a laboratory scale motor. There are several requirements for realizing this type of hybrid rocket: 1) high fuel filling rate for obtaining an optimal ${\zeta}$; 2) small port intervals for increasing port merging rate; 3) ports arrayed across the entire fuel section. Because these requirements could not be satisfied by common manufacturing methods, no previous researchers have conducted experiments with this kind of hybrid rocket. Recent advances in high accuracy 3D printing now allow for fuel to be produced that meets these three requirements. The fuel grains used in this study were produced by a high precision light polymerized 3D printer. Each grain consisted of an array of 0.3 mm diameter ports for a fuel filling rate of 98% .The authors conducted several firing tests with various oxidizer mass flow rates and chamber pressures, and analysed the results, including ${\zeta}$ history, using a new reconstruction technique. The results show that ${\zeta}$ remains almost constant throughout tests of varying oxidizer mass flow rates, and that regression rate in the axial direction is a nearly linear function of chamber pressure with a pressure exponent of 0.996.