Investigation of flow field and convective heat transfer of narrow-clearance Taylor-Couette-Poiseuille flow with limited axial length

In industrial applications, Taylor-Couette-Poiseuille (TCP) flows are usually characterized by limited axial scope and eccentricity. The aerodynamic and thermal performance characteristics of these flows strongly depend on the coupling between the end leakage and axial throughflow. This study addressed the flow field and convective heat transfer characteristics of limited-length TCP flows (limited TCP flows); the rotational Reynolds number ranged from 590 to 1110, eccentricity ratio ranged from 0.3 to 0.7, dimensionless clearance height ranged from 0.016 to 0.04, and axial Reynolds number ranged from 0 to 70. Axial throughflow induced upstream movement of the high-pressure zone and downstream movement of the low-pressure zone along the axial direction, constituting a novel finding. The shearing flow's static pressure was sinusoidal in the angular direction, with the maximum and minimum at theta = 0.73 pi and theta = 1.08 pi, respectively. For 0.375 < Z/L < 0.625, the line-averaged Nusselt number remained almost unchanged, whereas it increased sharply near the end of the clearance. The pressure and the Nusselt number increased as the rotational Reynolds number, eccentricity, and axial Reynolds number increased, and decreased as the dimensionless clearance height increased. At Re-a = 80, axial throughflow dominated the limited TCP flow. Compared with the limited Taylor-Couette flow, the axial throughflow increased the initial pressure of the gas film. In the central section, the angular distance between the maximal and minimal static pressures was smaller than for limited Taylor-Couette flow. The pressure and Nusselt number curves for the limited TCP flow were center-asymmetrical. Within the parametric range considered in this study, the limited TCP flow was almost laminar in the clearance, while it is highly turbulent as approaching to. Taylor vortices emerged near the clearance inlet but disappeared near the clearance outlet, distinct from the limited Taylor-Couette flow.