Application of Broadband Receptivity Data to the Amplitude Method for Transition Prediction

Abstract

Conventional hypersonic transition prediction relies upon the highly empirical [Formula: see text] method, which is predicated on theoretical approximations of relative disturbance growth. This does not account for the receptivity mechanism and the high degree of variability present in experimental wind-tunnel conditions, which itself leads to high degrees of variability in transition [Formula: see text] factors. The amplitude method, which better approximates the broadband nature of boundary-layer disturbances, was previously proposed to account for the effects of receptivity. In this study, high-fidelity simulated second-mode receptivity data for two blunt cones at Mach 10 to broadband disturbances are applied to an iterative approximation of the amplitude method tuned for second-mode dominated flows. The studied geometries consist of 9.525- and 5.080-mm-nose-radius 7 deg half-angle straight cones based on experimental cases from Arnold Engineering Development Center’s wind tunnel 9. Amplitude method predictions show improvement over the accuracy of [Formula: see text] estimates using standard threshold [Formula: see text] factors. In particular, the less blunt 5.080 mm cone demonstrates the best agreement due to its stronger second-mode response. The results of this work provide a preliminary framework for applying high-fidelity receptivity simulations to the amplitude method for transition prediction in hypersonic flows.