Impact of forward-facing steps on laminar-turbulent transition in transonic flows without pressure gradient

摘要

The influence of forward-facing steps on the amplification of disturbances in transonic flows is studied numerically. The main goal is to find a function for an additional amplification factor ΔN for a wide range of Mach numbers and step heights, which can be incorporated into the e~N method. In the present study both two-dimensional direct numerical simulation of disturbances as well as linear stability theory is used to gain detailed information on the flow. It is found that ΔN is a function of streamwise position, step location, step height and Mach number. Subsonic and supersonic results show differences in the flow topology and in the N-factor development, but effective ΔN factors are in the same order of magnitude.