MICROPHONE ARRAYS FOR COMPRESSED AIR LEAKAGE DETECTION

Compressed air energy is expensive, but common in industrial manufacturing plant. However, up to 30% of the generated compressed air energy is lost due to leakage. Best practice requires ongoing leak detection and repair. Leak detection in the ultrasonic frequency range using hand held devices is possible only over short distances as associated high-frequency waves with do not propagate well. Pressurized air escaping to ambient also generates frequencies below 20kHz. In this paper, beamforming in the audible frequency range is tested as a tool for localization of compressed air leaks at larger distances. Both advanced time and frequency domain beamforming methods have been implemented in a variety of situations on a laboratory experimental rig with several open blows representing leakage in a noisy environment typical of a factory setting. The advanced time domain broadband beamformer gives clearer initial noise maps than narrowband frequency domain approach as the broadband nature of the leakage is better exploited. The advanced beamforming in frequency domain is more effective in spatial resolution. Based on these initial results it is concluded that the microphone array approach has the potential to be a robust leak identification tool.