Numerical Investigation of the Effects of Different Turbulators on Heat Transfer in an Internal Flow System

Abstract

In this study, the effects of different turbulator geometries—specifically spring-type and twisted-tape turbulators—on heat transfer and flow characteristics in internal pipe systems were investigated using the Computational Fluid Dynamics (CFD) method. A straight pipe with a length of 1020 mm and a diameter of 12.7 mm was used as the reference model. Three different pitch lengths were evaluated for each turbulator type: 23 mm, 43 mm, and 63 mm for the springs, and 115 mm, 215 mm, and 315 mm for the twisted-tapes. The geometry and meshing were prepared using Gambit software, while numerical simulations were conducted in ANSYS Fluent, employing the Standard k-ε turbulence model. The CFD results demonstrated that the inclusion of turbulators significantly enhanced heat transfer compared to the plain pipe. The highest Nusselt numbers (Nu) were obtained with the shortest-pitch configurations, namely the 23 mm spring and the 115 mm twisted-tape. However, this enhancement was accompanied by an increase in the friction factor (f) and pressure drop, particularly as the turbulator density increased. Temperature distribution analysis revealed that in the plain pipe, cold fluid accumulated toward the center, whereas in turbulated configurations, heat distribution became more uniform and wall temperatures were reduced. Pressure field analysis also showed that decreasing the pitch of springs and twisted-tapes led to greater resistance and increased pressure loss along the pipe. The results are in strong agreement with both experimental observations and relevant literature, underscoring the importance of turbulator geometry and arrangement in optimizing the thermo-hydraulic performance of internal pipe flows.