My case is transient, supersonic( inviscid flow), compressible flow. In methodology of STAR-CD, "stagnation enthalpy" is recommened as thermal calcualation. And we must determine stagnation temperature. But in my case temperature in INLET is varied from 300 to 5000K. How do I determine stagnation temperature? So, I used the "thermal enthalpy" option about above case. Isn't this result resonable?

You should obtain good results with thermal enthalpy. Since the flow is high-speed, I would suggest total enthalpy, but I doubt the results will be much different. I don't think you can use stagnation enthalpy unless all the inflow boundaries have the same total enthalpy, which they don't in your case.

Thank you for kind answer, Richard.