Indirect combustion noise of auxiliary power units

Tam, Christopher K. W.; Parrish, Sarah; Xu, Jun; Schuster, Bill

doi:10.1016/j.jsv.2012.11.013

Cited by 26 publications

(12 citation statements)

References 10 publications

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“…Only a few investigations dedicated to APU noise have been reported in the literature, sometimes also in order to compare the APU system with the core of an aero-engine. Tam ( [8] and [9]) investigated isolated Honeywell APUs of different size, with respect to the frequency content, angular directivity and also with respect to a distinction between direct (originating in the combustion process itself) and indirect (being generated when entropy or vorticity fluctuations being accelerated or decelerated) combustion noise. Latter distinction was made assuming a common shape of combustion noise spectra, which was claimed to be universal.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Cycle Properties, Noise, and Air Pollutant Emissions of an APS3200 Auxiliary Power Unit

Siebel

Zanger

Huber

et al. 2018

Journal of Engineering for Gas Turbines and Power

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Auxiliary power unit (APU) operators face increasingly stricter airport requirements concerning exhaust gas and noise emission levels. To simultaneously reduce exhaust gas and noise emissions and to satisfy the increasing demand of electric power on board, optimization of the current technology is necessary. Prior to any possible demonstration of optimization potential, detailed data of thermodynamic properties and emissions have to be determined. Therefore, the investigations presented in this paper were conducted at a full-scale APU of an operational aircraft. A Pratt & Whitney APS3200, commonly installed in the Airbus A320 aircraft family, was used for measurements of the reference data. In order to describe the APS3200, the full spectrum of feasible power load and bleed air mass flow combinations were adjusted during the study. Their effect on different thermodynamic and performance properties, such as exhaust gas temperature, pressure as well as electric and overall efficiency is described. Furthermore, the mass flows of the inlet air, exhaust gas and fuel input were determined. Additionally, the work reports the exhaust gas emissions regarding the species CO 2 , CO and NOx as a function of load point. Moreover the acoustic noise emissions are presented and discussed. With the provided data the paper serves as a database for validating numerical simulations and provides a baseline for current APU technology.

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Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Cycle Properties, Noise, and Air Pollutant Emissions of an APS3200 Auxiliary Power Unit

Siebel

Zanger

Huber

et al. 2018

Journal of Engineering for Gas Turbines and Power

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show abstract

“…Other publications revealed the significance of entropy noise for combustion instability [105] even when accounting for entropy wave dispersion and dissipation effects [99]. Tam et al [106] demonstrated the contribution of entropy noise to the noise emission of auxiliary power units (APUs). Finally Knobloch et al [107] provided additional test cases for entropy noise generation in nozzle flows by presenting experimental results from the Hot Acoustic Test Rig (HAT).…”

Section: Fundamental Experimentsmentioning

confidence: 99%

Combustion noise: modeling and prediction

et al. 2019

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This paper reviews both direct and indirect combustion noise. For convenience, they will simply be referred to as combustion noise and entropy noise. Combustion noise has been studied for well over half a century. However, because of the large number of parameters involved and the complexities inherent in the combustion processes, a widely accepted theory has yet to be developed. For this reason, this review focuses primarily on experimental measurements, semi-empirical relations and empirical but practical prediction methodologies. Important characteristic features and empirical correlations of combustion noise based on open flames and engine noise data are highlighted. Plausible generation of entropy noise by the passage of entropy waves through a nonuniform mean flow was first predicted theoretically circa 1970s. But it took forty years for its existence to be confirmed experimentally. Since then, there have been numerous publications on this subject. They are the primary materials of this review. The fundamental experiment and noise generation mechanism will be discussed first. Of great practical importance is whether there is significant generation of entropy waves inside an engine. This issue and new methods for modeling and predicting internally generated engine entropy noise are items that are examined at some length. Recent advances in computational methods especially in large eddy simulation lead us to envision an important role to be played by high-fidelity numerical simulation in future combustion and entropy noise research and prediction. A critical evaluation of a strategy for investigating and predicting the generation and propagation of these noise components from the combustor of an engine to its exhaust is included in this review.

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“…The time-independent solution of equations (1) to (3) has been found analytically, e.g. see Tam et al 23 Therefore, details of the solution will not be shown. We will denote the mean flow variables by an overbar, e.g. "…”

Section: An Initial Value Problem Of Indirect Combustion Noise Generamentioning

confidence: 99%

“…In their study, Schuster and Mendoza 22 investigated such noise component from a Honeywell APU. In a slightly different effort, Tam et al 23 performed computational analysis to determine the frequency ranges over which their Honeywell RE220 APU had a high probability of emitting indirect combustion noise. They then searched their measured in-duct and far-field noise spectra for unexpected peaks in the same frequency ranges.…”

Section: Introductionmentioning

confidence: 99%

The physical processes of indirect combustion noise generation

Tam

Parrish

2018

International Journal of Aeroacoustics

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It is known that a uniform compressible flow supports three types of disturbances. One is entropy wave. These waves are made up of temperature and density fluctuations only. The other two are acoustic waves and vorticity waves. When entropy waves are convected into a nonuniform flow region, they are no longer independent waves. Their presence leads to pressure fluctuations, which result in noise radiation commonly referred to as indirect combustion noise. In the past, because entropy waves and acoustic waves are not independent waves in a nonuniform flow region, the mechanism responsible for the generation of indirect combustion noise had been attributed to mode coupling. That is, there is a coupling of entropy and acoustic modes. This leads to pressure fluctuations and hence noise radiation. The principal objective of the present investigation is to seek a more physical explanation of how indirect combustion noise is generated.

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Indirect combustion noise of auxiliary power units

Cited by 26 publications

References 10 publications

Experimental Investigation of Cycle Properties, Noise, and Air Pollutant Emissions of an APS3200 Auxiliary Power Unit

Experimental Investigation of Cycle Properties, Noise, and Air Pollutant Emissions of an APS3200 Auxiliary Power Unit

Combustion noise: modeling and prediction

The physical processes of indirect combustion noise generation

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