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To gather test data of the nonequilibrium flow in CO2 and investigate the influence of the two-temperature nonequilibrium model on numerical simulations, measurements of shock standoff distances over hypersonic spheres in CO2 have been taken in the hypervelocity ballistic ranges of the Hypervelocity Aerodynamics Institute, China Aerodynamics Research and Development Center. Corresponding numerical simulations using the two-temperature model were also performed. The measurements were made for spheres with diameters of 10 mm and 20 mm, flight velocities between 2.122 and 4.220 km/s, and ambient pressures between 2.42 and 14.74 kPa. Test flow fields were visualized by the shadowgraphy for the measurement of shock standoff distances. The shock standoff distances generally decrease as ρR (freestream density × radius of the model, namely the binary scaling parameter) increases. The flow is mainly nonequilibrium when ρR is of the order of 10−4 kg/m2, and the two-temperature nonequilibrium model is applicable for the calculation of the flow field under such conditions. When ρR increases to the order of 10−3 kg/m2, the flow approaches the equilibrium state.

In order to obtain the position changes of model flying freely with hypervelocity on the ballistic range, China Aerodynamics Research and Development Center (CARDC) applied the binocular vision technique to measure the model position. The binocular measurement stations were installed besides the room along the model flying direction, which would be calibrated and aligned to the global base reference coordinate system before the test. When the flying model with coded marking points on surface entered the measurement field, it would be illuminated by the extended laser beam with the pulse width of smaller than 10 ns, meanwhile, the two images of the target were obtained by the cameras. The model position was obtained by identifying and calculating coded marking points after the test. Based on solving the key technologies of obtaining clear images of the target, calibrating and aligning binocular measurement stations, dealing the model surface color and making marking points, the vision measurement system of the model position was accomplished on the 200 m free flight ballistic range of CARDC. The position changes of the 20° circular cone with the length of 165 mm were obtained by the vision measurement system, and the drag index and dynamic derivative of which were obtained by identifying, and the trend of the identified results were basic consistency with those on the G-Range of Arnold Engineering Development Center (AEDC). Meanwhile, the widespread application of vision imaging technique was validated by the test. Two new measurement technologies were developed. The first one was obtaining the image sequences, the other was obtaining the image of the target and shadow image at the same measurement field simultaneously. The image of the target for the debris cloud of aluminum sphere impacting aluminum plate at hypervelocity was obtained successfully.

To provide experimental data for validation of numerical simulations, measurement of shock stand-off distances over spheres in CO2 has been made in the hypervelocity ballistic range of Hypervelocity Aerodynamics Institute, China Aerodynamic Research and Development Center. The models were spheres with a diameter of 10 mm. The flight speeds were between 2.122 km/s and 4.220 km/s, with ambient pressures between 2.42 kPa and 12.3 kPa. The shock stand-off distance was measured using shadowgraph. Results revealed that high-temperature gas effect is more obvious in CO2 than in air, while two-temperature nonequilibrium model can basically reproduce the shock stand-off distances over spheres under present test conditions. The flow over spheres of present test is speculated to be mainly nonequilibrium. The accuracy and capability of two-temperature nonequilibrium model in CO2 may differ with different flow speeds and pressures, which need to be further investigated.

To investigate the angle of attack (AOA) effect of hypersonic boundary layer transition on slightly blunted cone, China Aerodynamics Research and Development Center has conducted a series of ballistic free flight experiments on 5° half angle circular cones. The projectile is 110 mm long with surface roughness between 0.46 μm and 0.77 μm. Six shots were taken under Mach 6 and separated unit Reynolds numbers, and the AOA varied between 0.2° and 7.9°. Results showed that the transition shifted upward to the nose tip on the leeside and afterward to the bottom on the windside within small AOA of less than 3°. When the angle got further increased, the moving direction of the transition on the windside reversed toward the nose tip but will not exceed the leeside in present results with nose tip radius of less than 0.4 mm. The transition Reynolds number without AOA was about 4.7 × 106, and there was a noticeable decrement with AOA, which may relate with both pressure gradient and wall heating difference.

To measure the shock stand-off distance for spheres with flight speeds above 5 km/s in air and provide experimental data for validation of theory and numerical methods, measurement of shock stand-off distance for hypersonic sphere has been conducted in the hypervelocity ballistic range of China Aerodynamic Research and Development Center. The measurement was made for spheres with diameters of 8, 10, 12 and 15 mm, flight speeds between 5.08 and 6.49 km/s, and ambient pressures between 1.5 and 6.3 kPa. The shock stand-off distance was measured using transient shadowgraph and schlieren. The measurement error was analyzed and found to be between about ±3\(\%\) and ±8\(\%\). Under present test conditions, the flow near the stagnation point is speculated to be primarily nonequilibrium. The shock stand-off distance near stagnation point increases as the binary scaling parameter \(\rho \)R increases. The data match well with previous investigations of similar conditions. Different values of \(\rho \)R may have different influence on the state of the flow with different speed near the stagnation point.

The impact of NOAA satellite sounding data on PRC's weather prediction model has been investigated using both 1979 FGGE and December 1987 datasets. Two experiments, NOSAT and SAT were conducted. Seven areas deemed to have adequate conventional data for definition of “truth,” were chosen to compute the verification statistics. The impact of satellite data was then assessed by changes in S1 skill score and root mean square errors for 24 and 48 h forecasts of sea level pressures and 500 mb height. A positive impact on rms errors of up to 11.5% was observed over land for SLP and 8% over ocean for 500 mb height for forecast period of 48 h. Some areas, however, show little or no improvement.

The impact of NOAA satellite sounding data on the numerical analysis and forecast system of the People's Republic of China has been investigated. Four experiments were conducted. They are: (1) NOSAT; which uses conventional data only and provides benchmark statistics for the performance of the forecast model, (2) SAT; which includes satellite and conventional data (3) ALLSAT; which uses satellite data only, except for conventional surface data required to define the 1000 mb height reference level, and (4) DATGUESS; which uses the ALLSAT analysis as the first guess to which conventional dat are then added. Seven areas deemed to have adequate conventional data for definition of truth. The impact of satellite data was then assessed by computing systematic errors, changes in S1 skill score and root mean square errors for 24 and 48 h forecasts of Sea Level Pressure (SLP) and 500 mb height. Overall, the Chinese model is found to underforecast the strength of features in the mean SLP fields, i.e., pressures are too low near high pressure systems and too high near low pressure systems. The same type of pattern is also seen in the mean 500 mb height forecast. In general, satellite data have been shown to reduce systematic error near where the data have been introduced in the vicinity of low pressure systems. A positive impact on root-mean-square errors of up 10 11.5% was observed over land for SLP and 8% over ocean for 500 mb height for forecast period of 48 h. However, only a meager increase of 5.5% in S1 skill score was observed at SLP for 48 h forecast over oceans.