Study on the Frequency-Wave Number Spectrum Calculation Method of Turbulent Boundary Layer of Arbitrary Curved Surface

The turbulent fluctuating pressure on the surface of the vehicle is the main excitation source of flow noise. It is of great significance to study the distribution characteristics of the frequency-wave number spectrum of the turbulent fluctuating pressure for line optimization of the vehicle and the control of flow noise. In this paper, a frequency-wave number spectrum calculation method for turbulent boundary layer fluctuating pressure on a curved surface is investigated. Firstly, the large eddy simulation method is used to calculate the unsteady flow field. After convergence of the flow field, several fluctuating pressure monitoring points are set on the surface of the vehicle along the flow direction to obtain the fluctuating pressure time series. Then Fourier transform is applied to the fluctuating pressure, the frequency domain cross-correlation matrix is calculated at each narrow band, and the wave number spectrum of each narrow band is estimated by array signal processing method. Finally, the wave number spectrum of each narrow band is combined to form a two-dimensional matrix, and the frequency-wave number spectrum of the turbulent fluctuating pressure on the surface of the vehicle is expressed in the form of a pseudo-color image. This method can be used to calculate the frequency-wave number spectrum characteristics of turbulent fluctuating pressure of arbitrary shape, which lays a foundation for the calculation and control of flow noise.