Turbulence Modelling effects on Tandem Cylinder Interaction Flow and Analysis of Installation effects on broadband noise using Chimera Technique

摘要

The NASA tandem cylinder benchmark case (L/D = 3.7) is studied numerically using novel variants of DES - the Delayed Detached Eddy Simulation (DDES) and the Improved Delayed Deteched Eddy Simulation (IDDES). The flow Mach number is 0.1285 and the Reynolds number is set to 166.000 to match th corresponding experiments at the NASA Langley Research Center (Jenkins et al., Lockard et al.). Incompressible simulations are carried out on a mandatory grid from the EC ATAAC project with approx. 9.5 million cells with a spanwise extent of 3.0D and flow normal domain extent of approx. 17.8D with symmetry boundary condition to mimic the closed experimental test section. In a second step a compressible IDDES simulation is done to evaluate the broadband noise of the configuration. Measurements are available from the QFF open jet facility. To capture the installation effects a combined grid of above mentioned cylinder core grid and a single stream jet grid is used. The communication between the grids is done by an overset chimera technique. The noise in the farfield is calculated by a standard FW-H method. The IDDES approach is designed to extend the LES region of the original DES approach (hybrid RANS/LES) from Spalart et. al. (1997) to the turbulent boundary layer, as proposed first by Travin et. al. in 2006. The non-zonal blending occures therefore inside the boundary layer - the RANS model acts as a wall model for the LES. The comparison of the simulations show the improvement of the results by using a IDDES.