| Title |
A Study on the Transitional Flows in a Concentric Annulus with Rotating Inner Cylinder |
| Keywords |
Transitional flow ; 천이유동 ; Concentric annulus ; 동심환형부 ; Pressure losses ; 압 력손실 ; Rotating flow ; 회전유동 ; Critical Reynolds number ; 임계 레이놀즈수 |
| Abstract |
The present experimental and numerical investigations are performed for the characteristics of transitional flow in a concentric annulus with a diameter ratio of 0.52, whose outer cylinder is stationary and inner one rotating. The pressure losses and skin- friction coefficients have been measured for the fully developed flow of water and glycerine- water solution(44%) with the inner cylinder rotating at speed of 0～600rpm, respectively. The transitional flow has been examined by the measurement of pressure losses to reveal the relation of the Reynolds and Rossby numbers with the skin-friction coefficients. The occurrence of transition has been checked by the gradient changes of pressure losses and skin- friction coefficients with respect to the Reynolds numbers. The increasing rate of skin-friction coefficient due to the rotation is uniform for laminar flow regime, whereas it is suddenly reduced for transitional flow regime and, then, it is gradually declined for turbulent flow regime. |