Wall Heat Load in Unsteady and Pulsating Combustor Flow

Despite the high interest in unsteady heat transfer phenomena, there is a fundamental lack of experimental and numerical work in this field. Moreover, the development of turbulence heat transfer models rely on the availability and accuracy of near wall data which are very difficult or even impossible to be measured. In recent years DNS has shown the capability to be used as a so called “numerical experiment” and has been applied to fill the gap between models and accurate data. In the present project DNS simulations were performed for a simple channel configuration with heat transfer. For the steady channel flow, the DNS results are validated against experimental data and very fine resolved DNS simulations available in the literature. Results are also shown and discussed for an unsteady pulsating flow. Neither numerical nor experimental results are available for the pulsating case involving heat transfer. In order to address the needs of turbulence modelling of unsteady near wall turbulent scalar transport the budget of the turbulent kinetic energy and its dissipation rate together with the budget of the turbulent temperature variance and its dissipation rate were determined at different time phases and for different values of the amplitude and frequency parameters. Thus, the present DNS database can be highly useful for future unsteady heat transfer closure development.