Underexpanded jet for testing laser-based combustion diagnostics

The design, construction, and operation of an underexpanded jet facility de veloped as a test flowfield for laser-based supersonic combustion diagnosti cs are described. The continuous-running device accelerates hot gases from a 160-kPa, 2000-K, stoichiometric H-2/Air combustion chamber through a 3.15 -mm i.d., alumina tube into a 11-kPa chamber. The resulting underexpanded j et of flame species provides a range of flowfield parameters (11 = 1-4, T = 1700-500 K, P = 72.8-2.7 kPa, and rho = 0.12-0.004 kg/m(3)) typical of pra ctical supersonic combustion experiments. The modeling of the jet flowfleld using an axisymmetric Navier-Stokes code is also described.