Physical modeling and correlation of separation length in hypersonic laminar ramp flows

To predict the separation length in hypersonic laminar flows over a ramp, the concepts of disturbance strength and anti-disturbance strength are introduced to characterize the key factors influencing boundary layer separation. It is found that the separation length is controlled by a normalized disturbance strength. Based on that, an analytical formula is derived to correlate the separation length with incoming flow conditions and ramp angle, which can predict the location of the separation under various flow and geometry conditions. The new correlation is compared to numerical simulations and experiments as well as the correlations in previous studies, confirming the suitability and effectiveness of the present analysis.