  Simulations of a supersonic, premixed, reacting flow over a wedge were
performed to investigate the effect of a boundary layer on the wedge surface on
ignition and stability of oblique detonation waves (ODWs). Two computational
domains were used: one containing a wedge of a single angle with a straight
after-body, and the other containing a double-angle wedge geometry. Both
domains were channels with a supersonic inflow of stoichiometric hydrogen-air
and a nonreflecting outflow, and the wedge was modeled using an immersed
boundary method. The compressible reactive Navier-Stokes equations were solved
using a high-order numerical algorithm on an adapting grid. Inviscid and
viscous wedge surfaces were modeled using slip and no-slip adiabatic boundary
conditions, respectively. Inviscid wedge surface cases are presented for a
range of inflow conditions and compared to previous work outlining several
different ODW structures. An ignition criterion is established as an accurate
method of predicting the formation of an ODW for a given inflow temperature,
Mach number, wedge angle, and length of the inviscid wedge surface. A viscous
wedge surface is then considered for a Mach 5 inflow at temperatures of 600 K,
700 K, and 800 K. The 600 K flow ignites in the boundary layer, but does not
detonate, while the 700 K and 800 K flows ignite and form ODWs. It was
determined that ODW formation depends on the degree of augmentation of the
leading oblique shock wave by the burning boundary layer and that ODW formation
is therefore predictable based on the ignition criterion. The 700 K flow
produces a unique oscillatory mode of a receding ODW followed by a redetonation
event occurring near the leading edge. A mechanism for this cycle, which
repeats indefinitely, is proposed.
