Investigation on compression ramp with surface V-groove for scramjet combustor

An experimental investigation was undertaken to study the shock structure and wall pressure distribution in a laboratory model of a scramjet combustor with a wall-mounted un-swept compression ramp. The ramp surface was provided with a V-groove and the semi-groove angle (SGA) was varied from 87.5° to 70° in the experiments. Some numerical simulations were also performed to study the possible enhancement of vorticity behind the ramp aft surface (RAS) as a result of the presence of V-groove on the ramp surface. A combustor inlet total pressure of 1000 kPa was maintained with air as medium for all the cold flow experiments in the present investigation. The laboratory model had a 50-mm long constant area section followed by a 150-mm long diverging section. A constant inclination of 2° to the bottom wall was made by the combustor top wall in the diverging section. A constant width of 25 mm throughout the length of the rectangular cross-sectional combustor was maintained. The entry Mach number to the combustor inlet (M_e) was 2.55. Schlieren images of shock structure in the internal flow and wall pressure (p_w) distributions were obtained from the experiments. A significant enhancement in vorticity in the symmetry plane immediately downstream of the un-swept ramp with surface V-groove (semi-groove angles between 70° and 80°) over the plain un-swept and swept ramp configurations (without groove) was observed from the numerical computations.