Nozzle startup in an oncoming flow

Starting of an axisymmetric convergent-divergent nozzle in a hypersonic flow

“…As in [4], the nozzle shape ( Fig. 1) is given by the entry and exit radii R 1 = R 2 = 1.63 and the lengths of the minimum section L 0 , the convergent L c and divergent L d channel sections, and the cylindrical region at the channel entry L e : L 0 = 1, L c = 5, L d = 1.3, and L e = 0.05.…”

“…This starting realizes a supersonic flow only in the divergent section of the nozzle. In [4] the starting in which a supersonic flow is also realized in the convergent section of a convergent-divergent nozzle, that is, in the diffuser. The starting of this type can become necessary in connection, for example, with the solution of the problem of stabilizing detonation combustion of a hydrogen-air mixture entering in the nozzle at a hypersonic velocity [5].…”

“…The steady flow pattern and the freestream Mach number effect on the result of the starting are numerically investigated. As distinct from [4], in the calculations the interaction between the gas flowing out of the nozzle and the external flow is taken into account.…”

Detonation combustion of hydrogen in a convergent-divergent nozzle with a central coaxial cylinder

“…It was numerically shown that the stabilization of detonation combustion in the divergent section of the nozzle requires the nozzle startup with the formation of steady supersonic flow throughout the entire channel. In [2] the starting of an axisymmetric Laval nozzle in a supersonic flow was calculated in a domain bounded by the inside nozzle enclosure. It was shown that in this case a return flow region can be formed near the channel wall in the divergent section.…”

“…In [3] it is proved that in an inviscid gas the oblique shock reflection from the axis of symmetry cannot be regular. The regular interaction obtained in [2] in numerically modeling on the basis of the gasdynamic Euler equations is supposedly the consequence of strong scheme viscosity, while the existence of the near-wall return flow region is due to the boundary conditions imposed on the nozzle exit. These two facts remain open the question of the feasibility of steady detonation combustion of a gas in an axisymmetric convergent-divergent nozzle.…”