• Journal of the Korean Society of Propulsion Engineers
• /
• v.16 no.6
• /
• pp.23-31
• /
• 2012

Present work deals three families of $SiO_2$ gelling agents which have been used to produce gel fuel based on Kerosene. Jet A-1 is chosen as fuel where power-law rheological model is used to confirm whether or not the gelification is achieved depending on the %wt of gellant. It was confirmed that the produced jelly-like substance have shear-thinning effect, and that its apparent viscosity increases as $SiO_2$ concentration increases. Compared to other gellants, gel with Aerosil(R) R972 fits most to the power-law model, while gels with Silica 230 and Silica 530 deviate from the power-law model. The rheological characteristics behaved differently depending on the mixing method(vortex mixing and manual mixing) when gellant concentration is increased.

• Nuclear Engineering and Technology
• /
• v.54 no.5
• /
• pp.1914-1928
• /
• 2022

To improve the heat transfer efficiency of the reactor fuel assembly, it is necessary to accurately calculate the two-phase flow boiling characteristics and the critical heat flux (CHF) in the fuel assembly. In this paper, a Eulerian two-fluid model combined with the extended wall boiling model was used to numerically simulate the 5 × 5 fuel rod bundle with spacer grids (four sets of mixing vane grids and four sets of simple support grids without mixing vanes). We calculated and analyzed 11 experimental conditions under different pressure, inlet temperature, and mass flux. After comparing the CHF and the location of departure from the nucleate boiling obtained by the numerical simulation with the experimental results, we confirmed the reliability of computational fluid dynamic analysis for the prediction of the CHF of the rod bundle and the boiling characteristics of the two-phase flow. Subsequently, we analyzed the influence of the spacer grid and mixing vanes on the void fraction, liquid temperature, and secondary flow distribution. The research in this article provides theoretical support for the design of fuel assemblies.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• v.y2005m4
• /
• pp.359-363
• /
• 2005

In SCRamjet engine, combustion occurs in supersonic flow with airbreathing. SCRamjet is characterized by very short combustion time in combustor, so it is very important to be mixing the air and fuel in short duration. Several methods are suggested for mixing enhancement. Among these, cavity is selected to study for enhancement of mixing. The numerical simulation is performed in the case of freestream Mach number of 2.5 and cavity located in front of fuel jet injection. CFD-Fastran, commercial code with three-dimensional Navier-Stokes equation with the Menter SST turbulence model were used. The results are obtained validate experiment results for same condition. Therefore, the numerical results show the mixing enhancement characteristics with a cavity.

• 한국연소학회:학술대회논문집
• /
• 2012.11a
• /
• pp.201-204
• /
• 2012

Combustion characteristics of boiler fuels made of bio-oil and light-oil were experimentally investigated. Bio-oil was obtained by fast pyrolysis of woody biomass. Emulsion fuel made by mixing bio-oil (up to 30wt%) with light-oil and surfactant was completely burnt, resulting in the formation of combusted gas containing CO concentration less than 10ppm. Simple mixtures of bio-oil and light-oil with separate delivery lines also gave nice combustion characteristics.

• Journal of the Korean Society of Safety
• /
• v.27 no.1
• /
• pp.20-25
• /
• 2012

The purpose of the study is to assess the extinguishing concentration of inert gases in engine nacelle fire. The experiment was performed with a two dimensional rectangular bluff body stabilized flames, where the fuel was ejected to counter flow and co-flow against an oxidizer stream. Two inert gases, $CO_2$ and $N_2$, were used for extinguishing agent in the oxidizer and methane was used for fuel. The main experimental parameters were the direction of injecting fuel, the kinds of agent and the velocity ratio between air and fuel streams, which controlled the mixing characteristic near bluff body and the strength of recirculation zone in the downstream. The result shows the flame structure and the mode were strongly dependent with fuel/air ratio and the fuel jet direction. For both flow configurations, the extinguishing concentration of $CO_2$ was smaller than the $N_2$ because of the large heat capacity of $CO_2$. However, the concentration of inert gasesat blowout was much smaller than those in the cup burner and coflow jet diffusion flames, which implies that the extinction mechanism of bluff body stabilized flames was mainly due to the aerodynamic aspect. Compared to co-flow fuel injection, the extinguishing concentration of inert gases under counter flow configuration was lower. The effect of direction might result from the mixing characteristic and strength of recirculation zonearound a bluff body. More details should be investigated for the characteristic of recirculation zone in the wake of bluff body using the LES(Large Eddy Simulation).

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.1
• /
• pp.220-227
• /
• 2010

The manufacturing of the solid fuel using wastes has been studied on the purpose of the reduction of green house gases and the profit-making as alternative fuel, and thus, it has become as technically improved as to be used as business. However, the production of solid fuel with multi-wastes combination needs a caution while the solid fuel with one-waste has not a significant component change. This study analyzes the solid fuel components through the practical plant experiment to the various wastes. The resulted data shows a different pattern than the theoretical one in the component analysis, and it can be concluded that the adequate uniform mixing has a great influence on the manufacturing of the solid soil.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.21 no.2
• /
• pp.395-400
• /
• 2017

The paper discussed the air-to-fuel ratio control of automotive fuel-injection systems using the cerebellar model articulation controller(CMAC) neural network. Because of the internal combustion engines and fuel-injection's dynamics is extremely nonlinear, it leads to the discontinuous of the fuel-injection and the traditional method of control based on table look up has the question of control accuracy low. The advantages about CMAC neural network are distributed storage information, parallel processing information, self-organizing and self-educated function. The unique structure of CMAC neural network and the processing method lets it have extensive application. In addition, by analyzing the output characteristics of oxygen sensor, calculating the rate of fuel-injection to maintain the air-to-fuel ratio. The CMAC may easily compensate for time delay. Experimental results proved that the way is more good than traditional for petrol control and the CMAC fuel-injection controller can keep ideal mixing ratio (A/F) for engine at any working conditions. The performance of power and economy is evidently improved.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.5 no.5
• /
• pp.67-72
• /
• 1997

The purpose of this study os to investigate how the natural gas in fuel blend influences the polutant emission of diesel engine. Four stroke cycle single cylinder engine is used for this experiment and four kind of fuel blends were made. Fuel blends show four different torque ratios between diesel oil and natural gas, which are 4 : 0. 3 : 1, 2 : 2 and 1 : 3. The constituents of exhaust gases of engine are analyzed for every fuel blend. The experimental results say that the mixing of natural gas into diesel fuel is an very effective way to reduce the amount of soot in the exhaust gas.

• Journal of the Korean Society of Combustion
• /
• v.4 no.1
• /
• pp.85-93
• /
• 1999

Experimental study on a porous ceramic liquid fuel combustor is performed. Compact burner with low pollutant emission and high combustion efficiency is realized through the use of porous ceramic materials of high porosities. The use of porous ceramic materials in burner material results in rapid vaporization of liquid fuel and enhancement in mixing process, and thus nearly premixed combustion of liquid fuel is achieved instead of diffusion and partially premixed combustion method, which is often used and apt to produce high pollutant emissions such as CO, NOx and soot. With this enhanced vaporization and premixing method of liquid fuel vapor and air, it is found that enhanced combustion process with intense radiation output and better emission characteristics in NOx, CO and soot emission, compared to other conventional liquid fuel burning method, are possible.

• Journal of the Korean Society of Combustion
• /
• v.12 no.2
• /
• pp.20-25
• /
• 2007

The supersonic combustion experiments are carried out using T3 free-piston shock tunnel. Hydrogen Fuel is injected in the cavity parallel with air(or nitrogen) flow. The equivalence ratios in this study are 0.132 and 0.447. Experimental measurements use OH-PLIF near the cavity and pressures in the combustor. For parallel fuel injection case, direct fuel add into cavity leads to increase of cavity pressure. And Flame exists just near the bottom wall for low equivalent ratio. There is no flame in the cavity because of no mixing in it. Compared to the inclined fuel injection, ignition delay length is longer for low equivalence ratio in both case. OH distribution is not a single line but a repeatable fluctuation flame structure by turbulence. Pressure distributions have nothing to do with the fuel injection position.