a b s t r a c tA shock-expansion tube (SET) is one of the major ground test facilities to generate really high-enthalpy and hypervelocity test flows. However, the strong shock wave may give rise to chemically non-equilibrium characteristic flow feature in a SET. In addition, the test time duration of a SET is extremely short which leads to difficulties in measurements and flow diagnostics. It is therefore appropriate to consider employing CFD approach, coupled with available experimental data, to determine the characteristic of the test flow in a SET. The dispersion-controlled dissipative scheme (DCD) is used for our simulation of chemically non-equilibrium flows associated with a SET. In this paper, the several numerical issues which occur in the computational investigation of the test flow in our SET facility are discussed. A new flux splitting algorithm based on local characteristics is worked out for the DCD scheme to mitigate any spurious oscillations. With the mentioned updated DCD scheme, the computed results compare well with the experimental data provided for validation.