A Theoretical and Experimental Investigation on Ejector Acoustics and Ejector Silencer Design

Ejectors are common devices used across many industries, however, they are often plagued by the presence of low frequency pressure pulsations causing both broadband and tonal noise. This thesis presents a theoretical and experimental investigation into the acoustics of an ejector-silencer combination with the emphasis placed on silencer design. More specifically, the noise generated by jet noise, the diffuser and natural modes are explained and estimated. The noise generation mechanisms of impingement tones and edgetones are presented but accurate predictions are found to be hard to make. An outline of the experimental facility is followed by the mechanical, acoustical and aerodynamic design details of the roughly 70:1 ejector scale model. A detailed analysis on the primary nozzle control and calibration is presented before diving into an aerodynamic and acoustic characterization of both the ejector and the wind tunnel facility. From experimentation, it is found that the placement of a perforated