Review of research on shock standoff distance for hypersonic sphere

Theoretical and experimental researches on shock standoff distance of hypersonic sphere are reviewed.For theoretical research,both theoretical arithmetics and engineering meth-ods can be used for rapid calculation of the shock shape and the standoff distance;while the nu-merical calculations mainly focus on the influence of the thermal and chemical gas models on the calculation results.These calculation methods are based on specific theories and particular experimental conditions,and thus the applicability of these methods is limited.For experimental research,nonequilibrium flow experiments in high enthalpy facilities are the key work at present.The application of the experimental data is worthy of study since each experiment is unique in experi-mental conditions and measuring methods.In addition,there is relatively insufficient experimen-tal data of other gas environments than air (such as CO2 ).The following problems can be further studied:improving the accuracy of theoretical and engineering calculation methods when real-gas effect is taken into account,studying the comprehensive influence of different thermal and chemi-cal gas models and chemical reaction models on the calculation accuracy,enhancing the launching ability of the ballistic range and developing more precise flowfield visualization techniques.