The Statistical Energy Analysis Of Vibro-acousitc Response Of Liquid Propellant Rocket Fairing

Fairing is in a broadband high pressure sound field when it is launched, which causes violent vibration of the structure. The sound pressure has bad effects on the inner instruments. Traditional deterministic methods, such as the finite element, limited by the theory and computational cost, their computational efficiency is low and the error is bigger in the high frequency. Statistical energy analysis(SEA) divides the complex system into subsystems, when energy is the basic parameter, the power flow balance equation is used to describe the relationship of the energy transmission between the subsystems. Other responses, such as displacement, velocity, pressure and so on can be obtained from the energy, this method can effectively solve the problem of high-frequency vibration.This paper first introduces the development and research status of statistical energy analysis, the basic principle,the basic parameters and the theoretical and experimental method to solve them are introduced. The modal method is applied to a simply supported rectangular plate and the results are compared with the ones obtained by SEA in order to verify the feasibility of the SEA, finally the limitations of the theory are pointed out.Virtual experiment is carried out on the fairing, random noise excitation is applied to the subsystem in turn, the velocity response of the faring and the sound pressure of the cavity are recorded, the energy of each subsystem is calculated, then according to sound pressure level, the noise power is calculated. Frequency response analysis is conducted on each subsystem, the modal density is calculated by counting modes. Divide full frequency band into octaves, plug sound power, energy of the subsystem, the center frequency into the power flow balance equation, inner loss factors and coupling loss factors of the fairing can be obtained.