Unsteady supersonic base flows around three afterbodies, cylindrical （Cy）, boattailed （BT） and three-step （MS）, are investigated in this paper. Reynolds-averaged Navier-Stokes （RANS） and two RANS/LES （large-e...Unsteady supersonic base flows around three afterbodies, cylindrical （Cy）, boattailed （BT） and three-step （MS）, are investigated in this paper. Reynolds-averaged Navier-Stokes （RANS） and two RANS/LES （large-eddy simulation） hybrid methods, detached eddy simulation （DES） and delayed-DES （DDES）, are used to predict the base flow characteristics around the baseline Cy afterbody. All the RANS and hybrid methods are based on the two-equation SST （shear-stress transport） model with compressible corrections （CC）. According to the comparison of measurements, both DES and DDES can produce more satisfactory results than RANS. RANS can only present the ＂stable＂ flow pat- terns, while the hybrid methods can demonstrate unsteady flow structures. DDES and DES results are little different from one another although the latter exhibits better agreement with the experiment. DES is taken to investigate the 5° BT and three-step afterbodies. The mean flow data and the instantaneous turbulent coherent structures are compared against available measurements.展开更多
This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic spee...This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic speeds,the formed shock waves are smeared compared to a conical boattailed projectile.Also,there is a reduction of the wake region behind the triangular base and the rear stagnation point is nearer to the projectile base resulting in base drag reduction.Moreover,there is an improvement of the stability of the triangular boattailed projectile since a lower overturning moment is incurred.展开更多
基金supported by the National Natural Science Foundation of China (10502030 and 90505005)Innovation and Support Foundation of Chinese Astronautics
文摘Unsteady supersonic base flows around three afterbodies, cylindrical （Cy）, boattailed （BT） and three-step （MS）, are investigated in this paper. Reynolds-averaged Navier-Stokes （RANS） and two RANS/LES （large-eddy simulation） hybrid methods, detached eddy simulation （DES） and delayed-DES （DDES）, are used to predict the base flow characteristics around the baseline Cy afterbody. All the RANS and hybrid methods are based on the two-equation SST （shear-stress transport） model with compressible corrections （CC）. According to the comparison of measurements, both DES and DDES can produce more satisfactory results than RANS. RANS can only present the ＂stable＂ flow pat- terns, while the hybrid methods can demonstrate unsteady flow structures. DDES and DES results are little different from one another although the latter exhibits better agreement with the experiment. DES is taken to investigate the 5° BT and three-step afterbodies. The mean flow data and the instantaneous turbulent coherent structures are compared against available measurements.
文摘This paper presents a computational study of the air flow past a triangular boattailed projectile.The study shows that there is a single normal shock wave impinges the projectile at transonic speeds.At supersonic speeds,the formed shock waves are smeared compared to a conical boattailed projectile.Also,there is a reduction of the wake region behind the triangular base and the rear stagnation point is nearer to the projectile base resulting in base drag reduction.Moreover,there is an improvement of the stability of the triangular boattailed projectile since a lower overturning moment is incurred.
