Validation of Solver program SPARC, with real-state measurements over an airfoil RAE-2822

Abstract

The aim of this investigation is to validate the test case of a transonic compressible flow in steady state over a RAE-2822 airfoil by means of computational fluid dynamics, CFD. A structured mesh in C-form surrounds the airfoil and meets the requirements of required y+. The two-dimensional study is carried out modifying different calculation configurations available in the solver, SPARC: flow model, dissipation, accuracy, and state of multigrid for which the solution is accepted. The flow conditions are Reynolds 6.5e6, Mach 0.729 and angle of attack 2.31°. The pressure coefficient (Cp) is compared against experimental data available from test case 6 in “Aerofoil RAE 2822 – Pressure distributions, and boundary layer and wake measurements”, contained in the “AGARD Report AR 138, 1979” [1]. In order to validate the results a smooth curve of pressure coefficient is accomplished to conduct the comparisons against the experimental data [1], and also against two other validations carried out by NASA with the solvers NPARC and WIND [3]. The study reveals good validating results, particularly for the Spalart-Allmaras model, and for its configurations in numerical-method schemes JST (Jameson-Schmidt-Turkel), JST83, and SLIP (Symmetric limited positive scheme) all three combined with dissipations of Standard Accuracy, and High Stability. However, the software yields solutions for the High Accuracy artificial dissipation for the lower multigrids in some cases; it has not been capable to compute any solution when the AUSM numerical method was selected; for the Matrix-Diss configuration some anomalies in the third multigrid-level occur; and for the K-ω model no satisfactory solution is obtained.