| Title |
Characteristics of Developing Turbulent Oscillatory Flows in a 180° Curved Duct with a Square Sectional by using a LDV |
| Authors |
Seok-Ju Yun ; Haeng-Nam Lee ; Hyun-Chull Sohn |
| DOI |
http://dx.doi.org/10.6110/KJACR.2015.27.7.344 |
| Keywords |
난류진동유동 ; 속도분포 ; 정사각 곡덕트 ; 진폭 ; 2차 유동 ; 무차원각진동수 ; 위상 Turbulent oscillatory flow ; Velocity distribution ; Square sectional curved duct ; Amplitude ; Secondary flow ; Dimensionless angular frequence ; Phase angle |
| Abstract |
In the present study the characteristics of turbulent oscillatory flows in a square-sectional 180°curved duct were investigated experimentally. A series of experiments for air flow were conducted to measure axial velocity profiles, secondary flow velocity profiles and pressure distributions. The measurements were made by a Laser Doppler Velocimeter (LDV) system with a data acquisition and processing system which includes Rotating Machinery Resolve (RMR) and PHASE software. The results from the experiment are summarized as follows. (1) The maximum velocity moved toward the outer wall from the region of a bend angle of 30°. The velocity distribution had a positive value extended over the total phase in the region of a bend angle of 150°. (2) Secondary flows were generally proportional to the velocity of the main flow. The intensity of the secondary flow was about 25% as much as that in the axial direction. (3) Pressure distributions were effects of the oscillatory Dean number and respective region. |