Fine Structure of Turbulence in a Boundary Layer with Strong Density Differences
Turbulent flows with strong density differences occur in a number of practical situations including premixed combustion over a strongly heated wall, the re-entry phase of a space shuttle into the atmosphere or the cooling of turbine blades by tangential injection. Although a number of well conducted studies exist on this topic (1,2,3) several questions concerning the detailed structure of the near wall turbulence remain unanswered. That is the case for instance when the mechanism generating the overall turbulent heat transfer is considered. Several investigations have converged to the observation that the heat transfer coefficient is independent of wall flux, even when the former is quite strong and enhances the ejection of low momentum fluid near the wall into the inner layer (3). The mechanism that compensates this phenomena and maintains unaffected the overall heat transfer mechanism is still not clear. The aim of the present investigation is to provide further experimental data obtained in a turbulent boundary layer subject to strong density differences Δρ in order to contribute to the understanding of these complex non equilibrium flows.
KeywordsHeat Transfer Coefficient Heated Wall Heat Transfer Mechanism Premix Combustion Wall Turbulence
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