Department of Aerospace Engineering & Applied Mechanics, Indian Institute of Engineering Science and Technology, Shibpur, Howrah-711103, India
The present study expresses the turbulent flow characteristics through a 90° pipe bend using a numerical method by determining the solutions for Reynolds Averaged Navier-Stokes (RANS) expression using the k-ω (SST) turbulence model. For that purpose, numerical analysis has been carried out by solving RANS equations using ANSYS FLUENT 16.2, considering incompressible fluid in turbulent flow conditions. Simulations have been carried out for three different Reynolds number ranging from 1×105 to 10×105 at three different bend curvature ratios (Rc/D = 1, 1.5, and 2). Pipe bends with guide vane are generally used where flow separation and space problem makes an issue in mechanical design. The presence of guide vane inside the bend positively suppressed the flow separation and presence of cross-flow which can cause the engine to run off design, thus reducing the engine efficiency. So, to observe the effect of guide vane and its position on turbulence characteristics, four different positions of guide vane inside the bend are considered in the present study. At first, an analysis was led to make sure that the results obtained from the present numerical model are reliable and in line with previous results obtained from similar published experiments and numerical work. Research has been conducted to find out the impact of Reynolds number, bend curvature ratio and position of guide vane on different turbulence characteristics namely; turbulent kinetic energy, turbulent intensity, and wall shear stress at bend outlet position. In general, the turbulent intensity is found larger for the lower bend curvature ratio at the inner wall curvature side. Results for turbulent kinetic energy have similarities in results with turbulent intensity. Significantly, the wall shear stress represented a strong dependency on the circumferential angle at the bend outlet cross-section, and curvature ratio rather than Reynolds number and guide vane positions.