Method for Measuring APU Inlet and Exhaust Sound Power Levels Under Constrained Testing Conditions

This paper proposes a method for measuring the sound power levels of Auxiliary Power Unit (APU) inlet and exhaust under constrained testing conditions. The method includes placing a baffle between the APU inlet and exhaust ports to reduce mutual interference between the noise sources and using soundproof blankets to cover the APU body to minimize vibration radiation noise. To reduce the influence of environmental reflections on the measurement results, the positions of the APU and microphones are adjusted. Additionally, a data processing method is presented to convert the sound pressure level data from the APU inlet and exhaust microphones into accurate sound power level data. This approach provides theoretical support for precisely measuring the sound power levels of APU inlet and exhaust in constrained environments, reducing the noise contribution from other sound sources that may affect the measurement results by more than 10 dB, offering a robust design entry for effective silencer design and noise control.