**5.1 Spike effect**

We observed that the shock wave scattered along the length and decreases the temperature in the vehicle nose surface from 1254 to a value of 1053 k from spike nose to the body nose respectively as noticed in **Figure 10**. The presence of the spike, blunt transforms the bow shock into a weaker conical shock.

**Figure 10.**

*Blunt spike temperature distribution.*

**Figure 12.** *Blunt spike pressure distribution.*

*Aero Heating Optimization of a Hypersonic Thermochemical Non-Equilibrium Flow… DOI: http://dx.doi.org/10.5772/intechopen.101659*

**Figure 13.** *Blunt spike density distribution.*

The high-speed flow traveled to the blunt body shoulder as shown in **Figure 11**, result in a reattached shock formation with a high-pressure zone in **Figure 12**, the unfavorable pressure gradient inverses the gas flow to the spike nose. Thus, a circumfluence zone was generated around the spick and the blunt body nose which induce a lower velocity than that after the conical shock, generating a shear layer.

represented in **Figure 13**, which reduces some of the fluid in the circumfluence area. So, the combined effect of the reduced foreshock and the recirculation zone on the main body can result in significant reductions in aero heating estimated by 16.67%.
