Duct Mode Measurements on the TFE731-60 Full Scale Engine

Sutliff, Daniel L.; Konno, Kevin E.; Heidelberg, Laurence J.

doi:10.2514/6.2002-2564

Cited by 11 publications

(7 citation statements)

References 4 publications

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“…The right-hand side vector {b} is partitioned accordingly. The matrix A can then be written in the form [20] and straightforward elimination of the terms below the main diagonal leads to [21] where…”

Section: High-performance Implementationmentioning

confidence: 99%

“…To conduct the numerical experiments, the modal composition of the acoustic signal inside the duct in terms of spinning modes is used to specify the source. Rotating rake measurements of these modes have been performed on an isolated engine by Sutliff, Konno and Heidelberg [21]. However, for the maximum power condition at which the experimental data were collected, modal data is not available.…”

Section: Introductionmentioning

confidence: 99%

“…In lack of an exact definition, the source is specified using modal data at a somewhat lower power setting for which the rotor tip speed is also supersonic. Even in this case, due to interference with the rake wake, the data for the rotor-locked mode, expected to be the dominant mode at large power settings, is contaminated in the measurements presented by Sutliff [21]. Under these circumstances, in order to gain insight into the propagation characteristics of the different spinning modes, several source definitions have been considered.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Computation of Engine Noise Propagation and Scattering off An Aircraft

Stănescu

Hussaini

et al. 2002

International Journal of Aeroacoustics

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Section: High-performance Implementationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computation of Engine Noise Propagation and Scattering off An Aircraft

Stănescu

Hussaini

et al. 2002

International Journal of Aeroacoustics

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“…Previous usage of the rotating rake measured only modes generated by rotor-stator vane interactions and were analyzed using the hardwall, plug flow solution. [16][17][18][19] In one application, the secondary interaction of the rotor-statorstrut interaction was detected, 20 but this was also a single rotational source, in a hardwall duct. Recently, the technique has been extended to include the solutions for lined ducts with plug flow 21 by analytically solving for the cylindrical wave equation with impedance boundary conditions at the inner and outer duct walls.…”

Section: Introductionmentioning

confidence: 99%

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Sutliff

2017

International Journal of Aeroacoustics

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The rotating rake mode measurement system was developed and implemented at the NASA Glenn Research Center in the 1990s to measure turbofan duct acoustic modes. The system is a radial rake with distributed microphones that is inserted into the duct and continuously rotates about the centerline. The rotating rake mode measurement system provides a complete map of the acoustic duct modes present in a ducted fan and has been used on a variety of test articles: from a low-speed concept test rig to full-scale production turbofan engines. Prior rotating rake mode measurement system measurements have occurred in environments with a single rotating source interacting with a stationary source to produce duct modes at the fan rotor harmonics. A recent test of a scale model high-speed research fan in the NASA 9 Â 15 ft Low Speed Wind Tunnel had two rotating sources, a rotor fan and a booster fan, on the same shaft. The interaction of the two rotating sources generated scattering at the harmonic sum and difference tones, and modal scattering at a given fan harmonic. Rotating rake mode measurement system data were acquired from this high-speed fan model which provided a database to allow for validation of the duct mode analysis technique expansion and experimental evidence of the scattering phenomenon. In this paper, modes from the two different sources and associated stationary surfaces from a sample fan condition were reported and compared to analytical predictions, in order to validate the ability of the rotating rake mode measurement system to measure scattered modes. Sample modal content of the booster fan tone and its harmonics tones are presented as well as the sum and difference interaction between the rotor and booster fans.

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“…Rice, et al 4 showed that the modal structure of the sound in the duct also determines the directivity of far field noise propagation; and Thomas,et al 5 demonstrated that the far field noise radiation can be used to estimate the modal structure in the duct. Various methods to measure noise in the engine and decompose it into the modal structure have been developed; including a rotating rake of microphones 6 , surface-mounted microphones in the inlet 7 , or a duct extension. 8 Heidelberg, et al 9 investigated the effect that modeshape has on acoustic performance of a liner.…”

Section: Introductionmentioning

confidence: 99%

Development of an Experimental Rig for Investigation of Higher Order Modes in Ducts

Gerhold¹,

Cabell

Brown

2006

12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference)

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Continued progress to reduce fan noise emission from high bypass ratio engine ducts in aircraft increasingly relies on accurate description of the sound propagation in the duct. A project has been undertaken at NASA Langley Research Center to investigate the propagation of higher order modes in ducts with flow. This is a two-pronged approach, including development of analytic models (the subject of a separate paper) and installation of a laboratory-quality test rig. The purposes of the rig are to validate the analytical models and to evaluate novel duct acoustic liner concepts, both passive and active. The dimensions of the experimental rig test section scale to between 25% and 50% of the aft bypass ducts of most modern engines. The duct is of rectangular cross section so as to provide flexibility to design and fabricate test duct liner samples. The test section can accommodate flow paths that are straight through or offset from inlet to discharge, the latter design allowing investigation of the effect of curvature on sound propagation and duct liner performance. The maximum air flow rate through the duct is Mach 0.3. Sound in the duct is generated by an array of 16 high-intensity acoustic drivers. The signals to the loudspeaker array are generated by a multi-input/multi-output feedforward control system that has been developed for this project. The sound is sampled by arrays of flush-mounted microphones and a modal decomposition is performed at the frequency of sound generation. The data acquisition system consists of two arrays of flush-mounted microphones, one upstream of the test section and one downstream. The data are used to determine parameters such as the overall insertion loss of the test section treatment as well as the effect of the treatment on a modal basis such as mode scattering. The methodology used for modal decomposition is described, as is a description of the mode generation control system. Data are presented which demonstrate the performance of the controller to generate the desired mode while suppressing all other cut on modes in the duct.

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Duct Mode Measurements on the TFE731-60 Full Scale Engine

Cited by 11 publications

References 4 publications

Computation of Engine Noise Propagation and Scattering off An Aircraft

Computation of Engine Noise Propagation and Scattering off An Aircraft

Interaction and scattered mode measurement in a mixed bypass/core duct with multiple rotating sources

Development of an Experimental Rig for Investigation of Higher Order Modes in Ducts

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