TIME-DOMAIN NUMERICAL-SIMULATION OF A FLOW-IMPEDANCE TUBE

An efficient method has been developed for. the application of the sur face acoustic impedance condition in time-domain solutions of aeroacou stic problems, such as the broadband-frequency simulation of a flow-im pedance tube, The basis for this method is the standard impedance cond ition stated in the frequency domain as the particle displacement cont inuity equation. The development of the time-domain impedance conditio n follows the relations among the frequency. z-, and discrete-time dom ains and a rational function representation of the impedance in the z- domain. The resultant impedance condition consists of finite, infinite -impulse-response type, digital filter operations in the time domain, which is very suitable to computational aeroacoustics algorithms. This paper describes the present approach and discusses the time-domain nu merical simulations of the NASA Langley how-impedance tube with a cons tant depth ceramic tubular liner. Both single and broadband-frequency simulations are performed. Excellent agreement is shown with experimen tal data at various frequencies and flow conditions. (C) 1998 Academic Press.