NUMERICAL UNCERTAINTIES IN TRANSONIC FLOW CALCULATIONS FOR AEROFOILS WITH BLUNT TRAILING EDGES

Numerical uncertainties are quantified for calculations of transonic f low around a divergent trailing edge (DTE) supercritical aerofoil. The Reynolds-averaged Navier-Stokes equations are solved using a lineariz ed block implicit solution procedure and mixing-length turbulence mode l. This procedure has reproduced measurements around supercritical aer ofoils with blunt trailing edges that have shock, boundary layer and s eparated regions. The present effort quantifies numerical uncertainty in these calculations using grid convergence indices which are calcula ted from aerodynamic coefficients, shock location, dimensions of the r ecirculating region in the wake of the blunt trailing edge and distrib utions of surface pressure coefficients. The grid convergence index is almost uniform around the aerofoil, except in the shock region and at the point where turbulence transition was fixed. The grid convergence index indicates good convergence for lift but only fair convergence f or moment and drag and also confirms that drag calculations are more s ensitive to numerical error.