Numerical Analysis of Combustion Chamber from Vibro-acoustic Coupling Characteristics Point of View

Purpose In this research, the vibro-acoustic coupling characteristic of the combustion chamber is investigated numerically. The governing equations consist of three main parts: the forced vibrations of the chamber shell (due to acoustic pressure fluctuations), the wave equation, and the interaction at the contact surface of the structure and the fluid (acoustic pressure and acceleration of the chamber). Methods As a finite element simulation, ABAQUS software simulates the proposed model (solving the linearized equations of motion), and frequencies and mode shapes of instabilities are calculated. Results The results show a reasonable agreement between the predicted values of dominant frequencies in the present model and those calculated by previous studies. Body temperature and thickness are considered parameters affecting the pressure frequency response and variations in dominant frequencies of the combustor, which are two sets of single-variable controlled experiments which may lead to sufficient credibility of the conclusion. According to the results, increasing the structure thickness makes the structure harder and reduces the maximum pressure amplitude. Also, the structure becomes softer with increasing body temperature. However, these findings are obvious and maybe less considerable, but these beneficial results offer sufficient material of archival value in the design process of the combustion chamber. The maximum pressure amplitude increases, reaches its maximum value at 427 ℃, and decreases. The results obtained are confirmed with similar works with appropriate accuracy. Conclusion It is found that the hardening of the structure reduces the amplitude of acoustic pressure fluctuations, which is valid for any structure when its stiffness is increased. Also, increasing the structure’s thickness can be considered a desirable approach in designing the combustion chamber by considering various limitations.