Mechanical EngineeringDepartment, Ferdowsi University of Mashhad
Mechanical Engineering Department, Ferdowsi University of Mashhad
Mecanical Engineering, erdowsi University of Mashhad
A quad inserted into a turbulent boundary layer of a flat plate and its effect on average heat transfer and the friction coefficient is studied. To optimize this effect, the edge sizes and distance of the quad from the flat plate are continually modified. In each case, simultaneously the heat transfer enhancement and reduction in skin friction are analyzed. For optimization, the genetic algorithm technique is employed and the results of each step of progress studied by following the Pareto curves. Physical domain is divided into control volumes, over which flow equations are discretized. To deal with the turbulence, several turbulence schemes are examined and appearance of flow features and stability in hard environments are monitored. The RNG k - ε turbulence model proved to give reliable solutions and stability to all the 1,600 cases under consideration. Based on the Pareto curve and with no single exceptions of the cases studied, results show that as the heat transfer coefficient rises, the skin friction falls simultaneously; in other words, there is an inverse relation between heat transfer enhancement and skin friction. Conclusion also made that the rate of heat transfer enhancement is more sensitive to modification on small area quads than those of large ones. Since the experimental validation of too many cases was impractical, random comparison between some numerical results and wind tunnel experiments is performed. The comparison showed that the numerical results are strongly in agreement with the experiments.