Active absorption of acoustic pulse in waveguide

Abstract

Object and purpose of research. A numerical model is taken as example to consider an active method of absorption for a short acoustic signal from reflecting boundary. Analysis is carried out on a model of virtual waveguide with rigid walls where the pulse with tonal content at one end and active absorption of the same at the other end is simulated. The purpose of studies is to assess the achievable method efficiency using a specific problem of signal absorption. Subject matter and methods. Signal propagation is estimated by finite element method using numerical model. The numerical calculations were verified by known analytical solutions according to the theory of wave propagation in waveguides. Main results. A numerical model is used as example to highlight the key tasks which have to be solved in the design of active signal absorption tools. Detailed consideration is given to the constraints of the waveguide model and acoustic signal to achieve the 9 dB efficiency obtained based on study results. Conclusion. The specific problem is taken to show that it is practically impossible to achieve full absorption of a short signal without reflection using only active methods. Conditions and ways of their implementation are identified without which it is impossible to achieve any significant effect by active absorption method.

Keywords

• helmholtz equation
• cylindrical waveguide
• acoustic pulse
• active cancellation methods
• active acoustic absorption