Numerical simulation of thermoacoustic instability in Rijke tube

The influence of three different states on the thermoacoustic instability characteristics of Rijke tube was compared in order to reseach the influencing factors of thermoacoustic oscillation by using the Rijke tube model with stack as the heat source. The thermoacoustic oscillations are numerically simulated from the start-up to the saturation state, and the effects of the temperature on the dynamic viscosity and the thermal conductivity are compared. The results show gravity has a greater influence than the thermoacoustic oscillation caused by thermal buoyancy, and it is related to the inner balance of the tube after the gravity and the temperature gradient caused by the protrusion and the temperature gradient caused by the reduction of the amplitude dissipation. For the comprehensive comparison of the two variable parameters, it is found that when the viscosity coefficient changes with temperature and the thermal conductivity is a fixed value, both of them decrease by 49.5% with the temperature change rate. This result far exceeds the viscosity coefficient itself influences. © 2021 Journal of Northwestern Polytechnical University.