Transition Experiments on Blunt Bodies with Distributed Roughness in Hypersonic Free Flight
Transition Experiments on Blunt Bodies with Distributed Roughness in Hypersonic Free Flight
复制标题
高超声速自由飞行中分布粗糙度钝体的转变实验
DOI：
10.2514/6.2007-306
复制
发表时间：
2007
影响因子：
27.7
通讯作者：
D. Prabhu
中科院分区：
文献类型：
--
作者：
D. Reda;M. Wilder;D. Bogdanoff;D. Prabhu
Blunt-body geometries were flown through carbon dioxide in the NASA Ames Hypervelocity Free Flight Aerodynamic Facility to investigate the influence of distributed surface roughness on transition to turbulence in CO2-dominated atmospheres, such as those of Mars and Venus. Tests were also performed in air for direct comparison with archival results. Models of hemispherical and spherically-blunted large-angle conical geometries were flown at speeds between 2.8 km/s and 5.1 km/s and freestream pressures between 50 Torr and 228 Torr. Transition fronts were determined from global surface heat flux distributions measured using thermal imaging techniques. Distributed surface roughness was produced by grit-blasting the model surfaces. Real-gas Navier–Stokes solutions were used to calculate non-dimensional correlating parameters at the measured transition onset locations. Transition-onset locations correlated well with a constant roughness Reynolds number based on the mean roughness element height. The critical roughness Reynolds number for transition onset determined for flight in CO2 was 223 ± 25%. This mean value is lower than the critical value of 250 ± 20% previously-established from tests conducted in air, but within the bounds of the expected measurement uncertainty.
