Investigating the effects of different innovative turbulators on the turbulent flow field and heat transfer of a multi-phase hybrid nanofluid

This study investigates the heat index by combining factors affecting the enhancement of heat transfer, including the modeling of three turbulators with 3D innovative geometries, hybrid nanofluid, including Cu and Al 2 O 3 , and high Reynolds numbers. Using the Eulerian method and the phase-coupled simple algorithm, a 3D tube in which turbulators with different sizes were embedded along with a hybrid nanofluid with a two-phase view were investigated. The geometry of rectangular turbulator is a = 1 cm, b = 3, 5, and 7 cm, and L = 40 cm, and geometry of twisted rectangular turbulator is like rectangular turbulator, and each part has a 5-cm length; also, the geometry of triangular turbulator is considered with b = 3, 5, and 7 cm, and L = 40 cm. In the two-phase view, because each phase can have a different velocity gradient and a different temperature gradient, the results were close to the experimental results. The results indicated that turbulators, hybrid nanofluid, and Reynolds number influenced heat transfer rate enhancement; for the rectangular turbulator, changing the turbulator size, volume fraction, and Reynolds number from the minimum values to the maximum values increased heat transfer by 49.17%. The same conditions increased heat transfer for the twisted rectangular and triangular turbulators by 44.28% and 45.19%, respectively. The proposed factors are practical and can be beneficial in heat transfer and fluid mechanics. Overall, at minimum conditions Re = 15,000 and φ = 0% up to maximum conditions Re = 25,000 and φ = 4% for rectangular, twisted rectangular, and triangular turbulators increasing heat transfer rates of 79.49%, 97.5%, and 82.45% have been observed, respectively.