Regularities of thermoacoustic oscillations in Lehmann’s plant with a coolant moving in reverse

Abstract

An approximate method is developed for calculating the instability boundaries, as well as the frequencies and amplitudes, of acoolant’s autooscillations self-excited during its motion in a vertical channel exposed to locally applied heat from a constant power source. Unlike in the classical generators of thermoacoustic oscillations such as the Rijke tube and Lehmann’s plant, it is assumed that the main stationary flow is collinear with the gravity force. In order to exclude the surging nature of the self-oscillations, it is assumed that the flow is created by a supercharger with a monotonically decreasing head-capacity characteristic. The resulting mathematical model makes it possible to theoretically determine the self-excitation conditions of the considered autooscillations and also to evaluate the effect of various parameters on their shape.