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정적 연소실에서 성층화된 혼합기 조건하의 점화 전극사이 당량비 측정과 연소 특성에 미치는 영향
배상수,이기철,민경덕,Bae, Sang-Su,Lee, Gi-Cheol,Min, Gyeong-Deok 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.10
To investigate only the effects of the stratified mixture distribution on initial flame propagation and combustion characteristics, the instantaneous equivalence ratio in the spark plug gap and combustion pressure were measured simultaneously In a constant volume chamber, To induce the stratified propane-air mixture distribution near the spark plug, counter-flow typed mixture injection system was used under the constant mean equivalence ratio $\Phi$$\_$mean/= 1.0 The instantaneous equivalence ratio was measured by a single-shot Raman scattering with narrow-band KrF excimer laser. The measuring error was within the limit of $\pm$ 3.5% provided that the proposed method was applied to the measured Raman signals. Judging from mass fraction burned derived from the measured pressure, the optimum combustion characteristics were shown under the condition that the local equivalence ratio in the spark plug was near 1.28$\pm$0.04, and these characteristics were more remarkable at the initial stage of combustion.
상세화학반응기구를 이용한 탄화 수소 및 메탄을 층류 화염 속도 모델링
배상수,민경덕,Bae, Sang-Su,Min, Gyeong-Deok 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.10
In order to be applicable to the combustion modelling of stratified charged combustion like that of - lean burn and GDI engine, the correlations of laminar burring velocities fur several hydrocarbon fuels and methanol are needed over a wide range of equivalence ratio, pressure and temperature. In this study, these correlations are modeled in the 1311owing form based on the experimental and Muller\`s modeling results for several fuels, where $\alpha$, ξ, and ξ are functions of pressure and temperature, $S_{L}$ =$\alpha$ exp[-ξ($\Phi$-$\Phi$$_{m}$)$^{2}$ -exp {-ζ($\Phi$-$\Phi$$_{m}$)}-ζ($\Phi$-$\Phi$$_{m}$)]. By using the results calculated by PREMIX code with Sloane\`s detailed chemical reaction mechanism for propane, it is verified that the coefficients of the abode modeling can be determined by considering laminar burning velocity data only in a range of equivalence ratio less than $\Phi$$_{m}$. Therefore, Muller\`s modeling results can be adopted leer modeling of the pressure and temperature dependency. Compared with the results of the existing Keck'and Gulder's models, those of the present one showed the good agreement of the recent experimental data, especially in the range of lean and rich sides.s.des.s.
상류 후류의 발달 주파수가 하류 익형의 비정상 경계층 거동에 미치는 영향
배상수(Sang Su Bae),강동진(Dong Jin Kang) 한국전산유체공학회 1999 한국전산유체공학회 학술대회논문집 Vol.1999 No.-
The effects of the frequency of upstream gust on the unsteady boundary characteristics on a downstream blade was simulated by using a Navier-Stokes code. The Navier-Stokes code is based on an unstructured finite volume method and uses a low Reynolds k-e turbulence model to close the momentum equations. The MIT flapping foil experiment set-up is used to simulate the interaction between the upstream wake and a blade. The frequency of the upstream wake is simulated by varying rate of pitching motion of the flapping airfoils. Three reduced frequencies. 3.62. 7.24. and 10.86. are simulated. As the frequency increases. the unsteady fluctuation on the surfaces of the downstream hydrofoil is shown to decrease while the upstream flapper wake has larger first harmonics of y-velocity component. The unsteady vortices are shown to interact with each other and. as a result, the upstream wake becomes undiscernible inside the inner layer. The turbulence kinetic energy shows asimilar behavior. Limiting streamlines around the trailing edge of the flapper are shown to conform with the unsteady Kutta condition for a round trailing edge. while limiting streamlines around the trailing edge of the hydrofoil conforms with the unsteady Kutta condition for a sharp edge.