**5.4 Jet spike configuration**

To reduce the huge heat load in the small area of the spike nose, we have proposed an assembly between the spike and the opposing jet configuration by introducing a jet into the nose of the spike to protect the nose from the overheating temperatures and minimize the cost of conventional thermal protection systems such as zirconium. **Figure 16** depicts the velocity of the velocity distribution in the analysis models with and without an opposing jet. The spike generates flow separation in the analytical model without an opposing jet, forming a primary recirculation zone in front of the blunt body. The major recirculation zone in the analytical model with opposing jet is substantially larger than in the model without opposing jet. The reason for this is because the recirculation zones generated by the spike and opposing jet squeeze and interfere with one another, resulting in the formation of a third recirculation zone in the middle. A larger main recirculation zone is formed by these three recirculation zones. This configuration limits the overheat load concentrated just in the frontal nose of the spike as shown **Figure 17**, this limits the cost of the thermal protection system needed in the nose area in the case without jet.

**Figure 18** represent the wall temperature for the two configurations spike and the assembly of the two systems, we notice that opposing jet spike have a better effect on the heat flux reduction with 502 K wall temperature compared to the spike configuration with 1205 K in the spike nose area by a reduction estimated by 58.33%.

Instead, the huge reduction in wall temperature is due to the initial jet temperature set of 300 K, where thermal equilibrium occurs between the flow near the wall and the initial jet flow [24].

**Figure 18.** *Wall temperature along with deferent configurations.*
