• Journal of Mechanical Science and Technology
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• 제15권1호
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• pp.117-124
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• 2001

This paper presents turbulent characteristics of an impinging F-O-O-F type injector in which fuel ad oxidizer impinge on each other to atomize under the different momentum ratio. Water was used as an inert simulant liquid instead of fuel and oxidizer. The droplet size and velocity in the impinging spray flow field were measured using a PDPA. The gradient of the spray half-width(b$_2$) along the long-axis direction declined throughout the entire spray flow field with increasing the momentum ratio from 1.19 to 6.48. However, the gradient of the half-width(b$_1$) along the short-axis direction decreased with increasing the momentum ratio. The turbulence intensity and turbulent kinetic energy were converged into the center of the center of the initial region with increasing the momentum ratio. As the momentum ratio increased from MR=1.19 to MR=6.48, the turbulent shear stress decreased. The results of this study can be used for the design of an impinging type injector for liquid rackets.

• 대한기계학회논문집B
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• 제31권12호
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• pp.1024-1032
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• 2007

The flow characteristics with the impinging angles of defrost nozzle jet inside a commercial vehicle passenger compartment were investigated experimentally by using the two-dimensional duct-nozzle model. The shape of the nozzle contraction was designed according to the curved line of cubic equation to the vertical plan of the flow direction. The impinging angles, defined as the angle between nozzle axis and a vertical line to the windshield, were varied from the $0^{\circ}\;to\;80^{\circ}$. The mean velocity distributions, the half-widths, and the momentum distributions with the cases of both the free jet and the impinging jet onto the dummy windshield were measured. The impinging jet flows similarly with wall jet from $X/b_o=20$, and the impinging angle has an effect on the half-width of the impinging jet. The momentum distributions onto the windshield increased with the increase of impinging angle, and then their inflection point was observed around the impinging angle of $60^{\circ}$.

• 설비공학논문집
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• 제3권5호
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• pp.395-403
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• 1991

The purpose of this investigation was to characterize nucleate boiling and burn-out heat flux for rectangular free jet with saturated water impinging perpendicularly and upward against a flat uniform heat flux surface. Heat flux measured for Reynolds number based on rectangular nozzle width and for aspect ratio. The result of nucleate boiling heat transfer was presented nondimensional experimental equation including Nusselt, Boiling, Subcooling, Reynolds and Weber number. The effect of aspect ratio of heated surface in the burn-out heat flux had not appeared distinctly. But for the same aspect ratio, burn-out heat flux increased linearly with increment of nozzle exit velocity.

• 대한기계학회논문집
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• 제14권3호
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• pp.716-724
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• 1990

본 연구에서는 2차원 경사충돌분류에 대한 실험을 수행하였고, 이 결과를 수] 치해석에 의한 계산치와 비교하였다. 실험에서는 난류특성을 구명하기 위하여 열선 풍속계를 사용해 충돌각의 변화에 따른 평균속도, 각 난류응력성분, 압력등을 측정하 였다.수치해석을 위한 난류모델로는 표준 K-.epsilon.모델을 사용하였다.

• 동력기계공학회지
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• 제13권5호
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• pp.34-39
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• 2009

In this paper, the CFD analysis using various turbulent models has been performed to evaluate which type of turbulent models can predict well the mixing flow structure of $45^{\circ}$ impinging round jet. This CFD analysis has been carried out through the commercial Fluent software. As a result, any of turbulent models cannot predict the experimental results definitely all over the flow range. However, as compared with the experimental results, the turbulent model of realizable(RLZ) k-$\varepsilon$ only predicts well in the limited range between X/$X_0=1.1$ and X/$X_0=2.0$.

• 태양에너지
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• 제18권3호
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• pp.217-228
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• 1998

축류비가 5이고 형상비가 7인 장방형(長方形) 노즐을 사용하여 연직 상향의 3차원 자유 충돌 수분류계를 구성하였다. 수평 충돌판에 상향의 장방형 충돌수분류가 충돌할 때, 보조수를 동반하지 않은 단일수분류 및 보조수를 동반하는 수분류에 대하여 노즐-충돌판 사이의 거리, 노즐출구 속도를 변수로하여 노즐의 긴변 방향과 짧은 변 방향에 대하여 전압 및 정압 분포를 측정하였다. 이때 충돌판상에서 정압이 영이 되는 국소 위치까지의 거리인 충돌 반폭을 구하고, 최고 압력을 나타내는 정체점을 기준으로 무차원 정압 분포식을 제시하였다. 또한 각 실험조건에서 정체점상에서의 충돌속도를 구하였으며, 충돌속도는 노즐-전열면간 거리가 증가함에 따라 감소하며 그 감쇄율은 삼차원 자유 분류의 특성감쇄 영역의 유동 특성을 갖는다.