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Spectral methods have previously been applied to analyze a multitude of vibration and acoustic problems due to their high computational efficiency. However, their application to interior structural acoustics systems has been limited to the analysis of a single plate coupled to a fluid-filled cavity. In this work, a general multidomain spectral approach is proposed for the eigenvalue and steady-state vibroacoustic analyses of interior structural-acoustic problems with discontinuous boundaries. The unified formulation is derived by means of a generalized variational principle in conjunction with the spectral discretization procedure. The established framework enables one to easily accommodate complex systems consisting of both a structure assembly and a built-up cavity with moderate geometric complexities and to effectively analyze vibroacoustic behaviors with sufficient accuracy at relatively high frequencies. Two practical examples are chosen to demonstrate the flexibility and efficiency of the proposed formulation: a built-up cavity backed by an assembly of multiple connected plates with arbitrary orientations and a thick irregular elastic solid coupled with a heavy acoustic medium. Comparison to finite element simulations and convergence studies for these two examples illustrate the considerable computational advantage of the method as compared to finite element procedures. [ABSTRACT FROM AUTHOR]

• The role of stator parameters in the propulsion performance and unsteady forces of a pump-jet propulsor is investigated through a numerical simulation. • The shear-stress transport (SST) k–omega turbulence model together with the sliding mesh technique are employed to simulate the three-dimensional unsteady flow. • The line-spectrum amplitudes of the unsteady rotor forces are numerically analyzed. • A method based on time domain statistics is employed to reflect the fluctuating amplitude characteristic of the unsteady pressures on the whole blade surface of the rotor. Rotor-stator interaction of a pump-jet propulsor can induce strong pressure fluctuations and vibrations, which may deteriorate the vibration and acoustic performance and cause damage to the propulsion system at some severe working conditions. In this paper, the role of stator parameters, such as the prewhirl angle, the rotor-stator spacing and the chord length of the stator blades, in the propulsion performance and unsteady forces of a pump-jet propulsor is investigated through a numerical simulation. The shear-stress transport (SST) k–omega turbulence model together with the sliding mesh technique are employed to simulate the three-dimensional unsteady flow. The propulsion performance is obtained from the steady simulation at nine advance ratios. Take the steady result as the initial flow field, the convergence usually occurs in one revolution of the rotor in the unsteady computations. For the unsteady computation analysis, the line-spectrum amplitudes of the unsteady rotor forces are analyzed, and a method based on time domain statistics is employed to reflect the fluctuating amplitude characteristic of the unsteady pressures on the whole blade surface of the rotor. Since the pitch angle of the rotor blade decreases sharply along the radial direction, the velocity circumferential angle is corrected based on the blade pitch angle to reflect the fluctuation of rotor incidence angle in the circumferential direction. [ABSTRACT FROM AUTHOR]