Effect of dimple/protrusion depth on flow structure and heat transfer in a rotating channel with pin fin

In this study, numerical simulations are performed to investigate the effect of the dimple/protrusion depth on the flow structure and heat transfer characteristics in a rotating channel with pin fins. The pin fins are arranged with staggered layout. The longitudinal and transverses pitches of the pin fin are 2.5. The dimples/protrusions are located on the endwall surface between the pin fins. The print diameter of the dimple/protrusion is same as the pin fin. Five different dimple/protrusion depth-to-diameter ratios are investigated, i.e. δ/D=0,0.1,0.2,0.3,0.4. Results of the flow structure, heat transfer on the endwall are included in this study. It is found that the flow structure and heat transfer are sensitive to the rotational Coriolis forces, both on the leading side and trailing side. In the dimpled channel, the area of the low-speed recirculation is increased as the dimple depth increased. The trailing side has higher pressure and TKE compared to the leading side. In addition, the Nu number is high at the trailing side due to the Coriolis forces. In protrusion channel, the pressure is increased at the front of the protrusion as the protrusion depth increases. A counter-rotating vortex is found at the top of the protrusion. The Nusselt number is also higher at the trailing side compared to the leading side.