使下列文字符合学术表达方式   Fig. 9. shows the turbulent kinetic energy (TKE) distribution at the axial section of the test section. From the figure, it can be seen that the TKE close to the boundary-flow zone is much higher than that in the core-flow zone, which is attributed to the longitudinal swirl generated by the fluid passing through the bionic ribs to enhance the fluid disturbance. Higher TKE contributes to the disruption of the temperature boundary layer and accelerates the convective heat transfer, which indicates that more kinetic energy is consumed in the main flow direction and more pump power is required to maintain the fluid flow. The TKE of the W-SS enhanced tube is significantly higher than that of the N-SS enhanced tube, which indicates that the boundary-flow zone of the W-SS enhanced tube mixes more adequately with the core-flow zone, thus accelerating the convective heat transfer between the tube and the fluid. This is also the reason why the wall surface Nu of the W-SS enhanced tube is higher than that of the N-SS enhanced tube (Fig. 7(b)) and the temperature distribution is more uniform in the W-SS enhanced tube (Fig. 6). Therefore, The TKE enhancement in the enhanced tube is caused by multi-longitudinal swirls induced by the bionic ribs, and the increase in heat transfer capacity is directly related to the TKE enhancement. The above indicates that the increase of the TKE in the W-SS enhanced tube originates from the split seam structure of the shark skin bionic design.