Thermo-hydraulic performance and RSM-based optimization of a bio-inspired OctaMush turbulator in turbulent pipe flow

In this study, a novel bio-inspired turbulator, named the OctaMush turbulator, was experimentally investigated to enhance turbulent convective heat transfer in a circular tube under constant heat flux conditions. Experiments were performed using water within a Reynolds number from of 8000 to 15,000, while the effects of turbulator number and leg number were systematically examined. The thermal and hydraulic performances were evaluated in terms of the Nusselt number, friction factor, and performance evaluation criterion (PEC). The results demonstrated that the proposed turbulator significantly improved heat transfer compared to bare and supported tube configurations. The maximum Nusselt number enhancement reached approximately 149.6%, whereas PEC values remained above unity for all tested cases, varying between 1.19 and 1.62. FCCD-based Response Surface Methodology (RSM) was employed to statistically analyze the thermo-hydraulic performance and optimize PEC. The developed quadratic model showed high prediction capability with R2, Adj-R2, and Pred-R2 values of 99.14%, 98.37%, and 91.14%, respectively. Optimization analysis revealed that the optimum operating condition was obtained at Re = 12000, turbulator number ≈2.5, and leg number = 8, corresponding to a predicted PEC value of 1.3748. The obtained results confirm that the proposed bio-inspired OctaMush geometry offers a promising approach for thermo-hydraulic enhancement in turbulent internal flow applications.