An experimental study on natural convection in the annuli between two horizontal elliptic cylinders

수평타원 환상공간에서의 자연대류에 관한 실험적 연구

Experimental study has been carried out on natural convection in the annuli formed by two isothermal horizontal inner and outer elliptic cylinders with uniform gap. The eccentricities of inner and outer elliptic cylinder and the gap ratio for the experimental model were 0.5078, 0.389 and 0.363 respectively. The temperature distributions were obtained through the analysis of interferograms which were taken by Mach-Zehnder interferometer in the range of Rayleigh number (Ra$_{L}$) from 0.34*10$^{4}$ to 3.07*10$^{4}$. It showed that flow was laminar when Ra$_{L}$.leg. 2.5 *10$^{4}$, while above the range of Rayleigh number we could get information on the fluctuation of interference fringe. Therefore, the upper limit of Ra$_{L}$ for the correlation equation of mean equivalent conductivity in reference(1) is confirmed. The flow pattern could be visualized by simple smoke test. The comparison of streamlines, isotherms, temperature distributions and local equivalent heat conductivity between existing numerical and present experimental results showed good agreement.ement.

본 연구는 이중벽용기에서 볼 수 있는 환상공간에 관한 자연대류 연구로서 용기속에 들어있는 유체의 열차폐를 위한 최적의 가스두께를 측정하기 위하여 필요한 지식을 얻기위한 열전달 연구이다.