Open AccessThe article analyses a design procedure for the gas-dynamic energy separation device and shows that its performance efficiency is mainly dependent on the temperature recovery factor values r.
As a result of the performed analysis it was found, that the r values depend on a wide range of parameters, namely Mach and Reynolds number values, gas flow type, axial pressure gradient presence and its magnitude, surface relief, etc. At the same time Prandtl number is the parameter, which has the greatest effect on the r value.
A review of correlations available in publications to calculate r values is conducted for Prandtl number values equal to or less than 1 (which is consistent almost with all pure gases and their mixtures) and the obtained calculation results are compared with analytical expressions and available experimental data (for laminar and turbulent air flows, turbulent helium and hydrogen-argon mixture flow).
It is shown that for laminar boundary layer the correlation of square root of Prandtl number is in good agreement with the experimental and analytical data.
For turbulent flows the most widely known correlations were studied, and it was found, that for Prandtl number values equal to or less than 1 all of them lead to errors of at least 10 % and more.
A new correlation for r calculation with respect to Prandtl number is proposed with maximum error of 1,5 % for Prandtl number values equal to or less than 1.