Effcient numerical simulation of dense gas flows past airfoils and wings

Dense gases are single-phase vapors whose properties deviate significantly from the ideal gas law, operating at temperatures and pressures of the order of magnitude of the critical ones. Bethe-Zel’dovich-Thompson (BZT) fluids, which can be commercially available heat transfer fluids, form a particular class of dense gases for which nonclassical gasdynamic behaviors are theoretically predicted: they display a Fundamental Derivative of Gasdynamics Γ=1+ρc∂c∂ρS , with ρ the fluid density, c the sound speed, and S the entropy, that becomes negative in a range of thermodynamic conditions above the liquid/vapor coexistence curve. In that case, the compression shocks of the perfect gas theory violate the entropy inequality and are therefore inadmissible. Such non-classical phenomena have several practical outcomes: prominent among them is an active research effort to reduce losses caused by wave drag and shock/boundary layer interactions in turbomachines and nozzles, with particular application to Organic Rankine Cycles (ORCs). The complexity of setting up experimental studies with such dense gases has motivated the development of numerical tools to analyze their performance, assess their interest and define their optimal conditions of use. This study deals with the extension to dense gas flow computations of a low-cost preconditioned implicit scheme previousy developed for perfect gas flows.