Acoustic resonance phenomena in bypass channels for air in aviation engines

The existence of axiradial acoustic resonance oscillations of the main air flow in bypass channels of aviation engines is demonstrated theoretically and experimentally. Numerical and analytical methods are used to determine the frequency of the acoustic resonance oscillations for the lowest modes of open and closed bypass channels of the PS-90A engine. Experimental investigations reveal new acoustic resonance phenomena arising in the air flow in the cavities of the bypass channels in the main duct of this engine owing to instability of the main air flow. The results of numerical, analytical, and experimental studies of the resonance frequencies reached in the flow in the bypass cavities in the main duct of the PS-90A engine are found to be in reasonable agreement. As a result, the types of the resonance oscillations in the bypass channels can be accurately described.