湍流边界层壁面压力脉动波数频谱的归一化

Wavenumber-frequency spectrum is an important statistical tool for describing characteristics of turbulent boundary layer (TBL) wall-pressure fluctuations. Here, to further understand common characteristics of TBL wall-pressure fluctuations and support constructing prediction model, it is necessary to perform study on normalization of wavenumber-frequency spectrum of TBL wall-pressure fluctuations. Firstly, based on Lighthill equation, the compressible TBL wall-pressure fluctuations wavenumber-frequency spectrum prediction model was established, and the wavenumber-frequency spectrum normalization method was derived using source term optimization. Then, experiments were conducted in a low-speed wind tunnel to measure fluctuating pressure on wall surface of a flat plate turbulent boundary layer. Near-wall velocity distribution characteristics were obtained by using a hot-wire anemometer (HWA) to support construction of normalization method. By using surface arrays, auto-spectrum and wavenumber-frequency spectrum characteristics of TBL wall-pressure fluctuations under different wind speeds were obtained. Finally, based on experimental data, the constructed wavenumber-frequency spectrum normalization method was verified. The study showed that by reasonably optimizing source term in the prediction model, the wavenumber-frequency spectrum normalization method can be constructed; surface arrays can realize measuring auto-spectrum and wavenumber-frequency spectrum of TBL wall-pressure fluctuations, and more correctly reflect relevant characteristics of TBL wall-pressure fluctuations; by normalizing wavenumber-frequency spectrum, the applicability of the normalization method is verified, and it can be considered that the normalized wavenumber-frequency spectrum is independent of Mach number, Reynolds number and so on. This study can provide theoretical support for studying flow-induced noise problems in engineering fields of aviation, navigation and high-speed train.