Observations on the normal reflection of gaseous detonations
Experimental results are presented examining the behavior of the shock wave created when a gaseous detonation wave normally impinges upon a planar wall. Gaseous detonations are created in a 7.67-m-long, 280-mm-internal-diameter detonation tube instrumented with a test section of rectangular cross section enabling visualization of the region at the tube-end farthest from the point of detonation initiation. Dynamic pressure measurements and high-speed schlieren photography in the region of detonation reflection are used to examine the characteristics of the inbound detonation wave and outbound reflected shock wave. Data from a range of detonable fuel/oxidizer/diluent/initial pressure combinations are presented to examine the effect of cell-size and detonation regularity on detonation reflection. The reflected shock does not bifurcate in any case examined and instead remains nominally planar when interacting with the boundary layer that is created behind the incident wave. The trajectory of the reflected shock wave is examined in detail, and the wave speed is found to rapidly change close to the end-wall, an effect we attribute to the interaction of the reflected shock with the reaction zone behind the incident detonation wave. Far from the end-wall, the reflected shock wave speed is in reasonable agreement with the ideal model of reflection which neglects the presence of a finite-length reaction zone. The net far-field effect of the reaction zone is to displace the reflected shock trajectory from the predictions of the ideal model, explaining the apparent disagreement of the ideal reflection model with experimental reflected shock observations of previous studies.
© 2017 Springer-Verlag GmbH Germany. Received: 7 February 2017. Revised: 5 June 2017. Accepted: 6 June 2017. First Online: 26 June 2017. Communicated by N. Smirnov. The authors would like to thank Jeff Odell for his enthusiastic help in designing the splitter plate, Bahram Valiferdowsi for his tireless energetic support in assembling the experiment, and Frank Kosel of Specialised Imaging for providing a demonstration of the SIMD16 camera. We thank Knut Vaagsaether and Daj Bjerketvedt of Telemark University College for their assistance in interpreting our model, particularly Knut for his numerical simulations.
Accepted Version - damazo_detreflect_sw.pdf