**4.3 Validation of opposing jet configuration**

Numerical results are compared with the experiment by NASA Langley in 1987 [24]. The radius of the cylinder is 25.4 mm and the thickness of the steel is 12.7 mm [35] (**Figure 9**). The free flow parameters are as follows (**Table 5**).

To investigate the effect of thermal protection systems we carried out a comparison between the opposing jet model and spike model at 26 km under the following free stream conditions illustrated in **Table 6**.

### **Figure 9.**

*Flow field wave structure of opposing jet; (a) our numerical photograph result; (b) experimental Hayashi photograph [24].*


#### **Table 5.**

*Opposing jet free stream boundary condition [35].*

