16 research outputs found
Incipient Separation in Shock Wave Boundary Layer Interactions as Induced by Sharp Fin
The incipient separation induced by the shock wave turbulent boundary layer
interaction at the sharp fin is the subject of present study. Existing theories
for the prediction of incipient separation, such as those put forward by McCabe
(1966) and Dou and Deng (1992), can have thus far only predicting the direction
of surface streamline and tend to over-predict the incipient separation
condition based on the Stanbrook's criterion. In this paper, the incipient
separation is firstly predicted with Dou and Deng (1992)'s theory and then
compared with Lu and Settles (1990)' experimental data. The physical mechanism
of the incipient separation as induced by the shock wave/turbulent boundary
layer interactions at sharp fin is explained via the surface flow pattern
analysis. Furthermore, the reason for the observed discrepancy between the
predicted and experimental incipient separation conditions is clarified. It is
found that when the wall limiting streamlines behind the shock wave becomes\
aligning with one ray from the virtual origin as the strength of shock wave
increases, the incipient separation line is formed at which the wall limiting
streamline becomes perpendicular to the local pressure gradient. The formation
of this incipient separation line is the beginning of the separation process.
The effects of Reynolds number and the Mach number on incipient separation are
also discussed. Finally, a correlation for the correction of the incipient
separation angle as predicted by the theory is also given.Comment: 34 pages; 9 figure