Fluid Pressure Response at the Straight Pipe Outlet Under Random Axial Vibration

This paper investigates the fluid pressure response at the outlet of a vertical fluid delivery straight pipe under random axial vibration. Based on the classical fluid–structure interaction (FSI) 4-equation model and forced vibration theory, the FSI equations of motion of the pipe under random axial vibration are established. Then, the variance of the pressure response at the pipe outlet is solved by combining the pseudo-excitation method and the characteristic line method. The correctness of the proposed method is verified by comparing the results obtained by the proposed method with the Monte Carlo simulation method. Since the pseudo-excitation method can directly obtain the pressure variance without many sample calculations, the method in this paper has high computational efficiency. The influence laws of fluid velocity, pressure, pipe structural parameters, and power spectral density of random vibration on the pressure response of pipe outlet are analyzed. The results show that the effect of random axial vibration on the fluid pressure response at the pipe outlet is significant and cannot be ignored. Increasing the pipe's inner diameter or shortening the pipe's length is beneficial in reducing the fluctuation of the pressure response at the outlet of the pipe. The analytical method in this paper can effectively analyze the outlet pressure of the pipe under random axial excitation and can provide a theoretical basis for reducing the fluid pressure fluctuation in the pipe under random vibration.