Chemical reactions of fuel combustion and nitrous-oxide decomposition used to generate and heat the test gas in a high-enthalpy short-duration facility

Operation of a short-duration high-enthalpy facility with a double plenum chamber with reproduction of natural values of stagnation pressure and physical stagnation enthalpy in the incoming flow is studied. The test gas is heated by burning the following compositions in the first chamber: hydrogen or propane (three-component initial mixture: fuel + air + compensating oxygen) or a combination of these fuels with nitrous oxide (four-component initial mixture: fuel + nitrous oxide + air + compensating oxygen or compensating nitrogen). For all fuels, the composition of the initial mixture pumped into the first chamber ensures generation of a flow with the mass fraction of oxygen equal to the mass fraction of oxygen in atmospheric air $(0.231)$. Computations are performed for the range of Mach numbers $\mathrm{M}_{\mathrm{H}}= 4-7$ and a flight trajectory with a dynamic pressure of $\approx0.6$ bar.