<正> Unsteady supersonic base flows around threeafterbodies,cylindrical(Cy),boattailed(BT)and three-step(MS),are investigated in this paper.Reynolds-averagedNavier-Stokes(RANS)and two RANS/LES(large-eddysimulation)hybrid methods,detached eddy simulation(DES)and delayed-DES(DDES),are used to predict the base flowcharacteristics around the baseline Cy afterbody.All theRANS and hybrid methods are based on the two-equationSST(shear-stress transport)model with compressible correc-tions(CC).According to the comparison of measurements,both DES and DDES can produce more satisfactory resultsthan RANS.RANS can only present the 'stable' flow pat-terns,while the hybrid methods can demonstrate unsteadyflow structures.DDES and DES results are little differentfrom one another although the latter exhibits better agree-ment with the experiment.DES is taken to investigate the5~ BT and three-step afterbodies.The mean flow data andthe instantaneous turbulent coherent structures are comparedagainst available measurements.
Zhixiang Xiao Song Fu School of Aerospace Engineering,Tsinghua University, 100084 Beijing, China
