Numerical evaluation of flow conditions in the LENS reflected shock-tunnel facilities

The calculation process of the flowfield of the nozzles of the Calspan-UB Research Center reflected shock tunnel facilities has been described. These calculations utilize a full Navier-Stokes solver based on the robust data-parallel line relaxation method coupled with chemical and vibrational non-equilibrium effects as well as the inclusion of a non-ideal equation of state necessitated by the high pressures in the reservoir of the shock tunnel. The calculation of the reservoir conditions and the modeling of the turbulent boundary layer in the throat region have been found to be the two most significant issues associated with the computation. With the use of the Spalart-Allmaras one-equation model, the error calculated by comparing the solution to measured Pitot pressure profiles in the test section are nominally +/- 5% or less for all the cases considered. In addition to good agreement with the available experimental data, the calculations have proven to be important in the understanding of the flow interactions during the nozzle expansion and have provided a means of evaluating new nozzle throat inserts to generate new capability ranges for the facilities.