Development of a Far-Field Noise Estimation Model for an Aircraft Auxiliary Power Unit

Ahmed, Umair; Ali, Fakhre; Jennions, Ian K.

doi:10.1109/access.2021.3112390

Cited by 7 publications

(8 citation statements)

References 29 publications

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“…The authors have initiated research on the development of a microphone-based condition monitoring solution by first considering the far-field noise as a probable source of information about the health of the system. This led to the development of a far-field noise estimation model [7]. Sensitivity analysis has been performed using the developed model to quantify the effect of APU component degradation on the far-field noise.…”

Section: A Backgroundmentioning

confidence: 99%

“…The use of microphones is also common for noise measurements [4], its effect on airline employees [5], and the design of noise abatement solutions [6]. A recent study employed far-field microphone data to develop and validate a far-field noise estimation model for the complete range of APU operating conditions [7].…”

Section: B Literature Reviewmentioning

confidence: 99%

“…The Boeing 737-400 APU is a single-shaft gas turbine engine with a load compressor and a generator to support pneumatic and electrical loads (Fig. 1 in [7]). The APU has two centrifugal compressors (one for the power section and one for APU pneumatic system) with 17 impellers each, while the radial turbine has 14 blades.…”

Section: Boeing 737-400 Apu Operationmentioning

confidence: 99%

“…This is achieved by varying the SCV angles by changing the current through the SVTM, from 50mA for BL ON NL to a maximum of 95mA for BL ON LD conditions. The effects of load conditions on the APU thermodynamic parameters and the far-field noise have already been discussed [7].…”

Section: Boeing 737-400 Apu Operationmentioning

confidence: 99%

“…The setup also includes a camera facing the FADEC display for recording TOil, IGV angle, output pressure from the Load Compressor, and SVTM current. For mass flow through the bleed valve (ṁBleed) and load compressor (ṁLC), appropriate relationships have been used, details of which have been previously reported [7]. The complete dataset was acquired over a period of five months.…”

Section: B Experimental Data Collectionmentioning

confidence: 99%

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Evaluation of Aircraft Auxiliary Power Unit Near-Field Acoustics for Condition Monitoring

2022

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This paper presents a comprehensive evaluation of the near-field acoustics of an aircraft auxiliary power unit (APU), based on experimental data acquired from an in-situ APU. The aim is to establish whether near-field acoustics can be implemented for online condition monitoring. The APU of Cranfield University's demonstrator aircraft, a Boeing 737-400, has been instrumented to acquire acoustics (near-field and far-field) and vibration data in synchronization with aircraft state parameters under a wide range of operating conditions. The acquired data is first implemented to determine the efficacy of employing nearfield / far-field microphones, and vibration sensors, to monitor the combustion noise and tonal frequency levels from the APU components. Subsequently, an evaluation of the broadband characteristics of the vibroacoustic data and its variations against APU states and performance parameters is conducted based on several categories of feature extraction techniques. The findings suggest that nearfield acoustics lacks the ability to capture the combustion noise process. In addition, the tonal frequencies are also lost due to the level of background noise, fluctuations in the APU speeds, and scattering effects. For the same reasons, the phase couplings occurring between the signals generated by the APU components cannot be detected using acoustic data. Nevertheless, the overall analysis substantiates that the near-field acoustic data can be used to predict the APU operating states and has the potential to be implemented for developing APU performance parameter estimation models to enable condition monitoring.

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Section: A Backgroundmentioning

confidence: 99%