Boundary Layer Profile Behind Gaseous Detonation as it Affects Reflected Shock Wave Bifurcation

Abstract

The present study explores the flow field created by reflecting detonations using heat transfer and pressure measurements near the location of detonation reflection. Schlieren imaging techniques are used to examine the possibility of shock wave-boundary layer interaction. These measurements are compared to laminar boundary layer theory and a onedimensional model of detonation reflection. Experiments were carried out in a 7.6 m long detonation tube with a rectangular test section using mixtures of stoichiometric hydrogenoxygen with argon dilution of 0, 50, 67, and 83% at an initial pressure of 10, 25, and 40 kPa. Optical observations show that minimal interaction of the reflected shock wave results when propagating into the boundary layer created by the incident wave. The heat transfer rate is qualitatively consistent with the time dependent laminar boundary layer predictions, however the magnitude is consistently larger and substantial (factor of three) peak-to-peak fluctuations are observed. The pressure measurements show good agreement between predicted ideal incident and reflected wave speeds. The pressure amplitudes are under-predicted for no argon dilution cases particularly at 40 kPa, but in reasonable agreement for lower pressures and higher dilutions.

Dynamics of hydrogen–oxygen–argon cellular detonations with a constant mean lateral strain rate

“…The results from Fig.17 indicate that the boundary layer behind H 2 /O 2 /Ar detonations is probably laminar, since the Reynolds number is smaller than the critical one of Re c ≈ 5.0 × 10 5 . This finding concurs with the previous conclusions of Liu et al [43] and Damazo et al [44] that the boundary layer behind stoichiometric H 2 /O 2 detonations is laminar. Therefore, Fay's turbulent boundary layer displacement thickness relation for evaluating the boundary layer induced mass divergence is quesitonable, and moreover, the present experiments can potentially act as a good framework for validating these relations.…”

Laser absorption of nitric oxide for thermometry in high-enthalpy air

“…Note, however, that the pressure rise between the incident shock and the reflected shock is not a step, but rather it occurs over a finite period of time and the pressure rolls off to its steady value. This is due to shock-bifurcation, a well-documented phenomenon in shock tubes with N 2 or air test gas (although it is not limited to only these test gases) [27,28]. Shock bifurcation makes it difficult to resolve measurements during the first 10-50 µs after the reflected shock passes the measurement plane.…”