Experimental study on spatiotemporal correlation and similarity law of transonic buffeting loads

Abstract

The spatiotemporal correlation of transonic buffet, driven by strong shock waves and boundary-layer separation, plays a critical role in causing structural vibrations in launch vehicles. To investigate this correlation, a wind tunnel experiment was conducted to measure the time-frequency characteristics of wall fluctuation pressures. The phase array approach was employed to obtain the spatial correlation of buffeting load. The results indicate that the low-frequency hydrodynamic modes dominate the separation flow and shock oscillation, while the attached flow is predominantly influenced by broadband acoustic modes. The space-time correlation analysis reveals that the peak buffeting load, for typical flows, results from the convergence of energy beneath the turbulent boundary layer. Furthermore, a similarity law for the spatial correlation of buffeting load was derived and validated by the measurement data. Based on the measured buffeting load data, an improved W–F (Wavenumber–Frequency spectrum) model with scaling spatiotemporal correlation was developed. This model serves as a theoretical foundation for predicting buffeting loads under flight conditions.