A Numerical Analysis of Tonal Acoustics in Rotor-Stator Interactions

Rangwalla, Akil A.; M., M.

doi:10.1006/jfls.1993.1037

Cited by 22 publications

(6 citation statements)

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“…and the quantity is added to both sides of equation ( 22), then equation ( 22) becomes (24) where , ( )/ , ( )/ , and ( )/ . Equation ( 24) is approximately factored and written in primitive variable form; it is solved as a series of sweeps in each coordinate direction…”

Section: Description Of the Unsteady Aerodynamics Codementioning

confidence: 99%

“…Ozyoruk and Long [23] use a high-order spatial scheme with the Euler or Navier-Stokes equations combined with a Kirchhoff surface to propagate the pre-assumed duct acoustic modes forward from the fan face to the far field. Rangwalla and Rai [24] used the time-accurate thin-layer Navier-Stokes equations to both generate and propagate duct acoustic modes that arise from a 2D rotor-stator interaction. A rescaling strategy was adopted to reduce the number of blades necessary to represent the correct blade-to-vane ratio.…”

Section: Introductionmentioning

confidence: 99%

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Ducted-Fan Engine Acoustic Predictions Using a Navier–stokes Code

Rumsey

Biedron

Farassat

et al. 1998

Journal of Sound and Vibration

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A Navier-Stokes computer code is used to predict one of the ducted-fan engine acoustic modes that results from rotor-wake/stator-blade interaction. A patched sliding-zone interface is employed to pass information between the moving rotor row and the stationary stator row. The code produces averaged aerodynamic results downstream of the rotor that agree well with a widely used average-passage code. The acoustic mode of interest is generated successfully by the code and is propagated well upstream of the rotor; temporal and spatial numerical resolution are fine enough such that attenuation of the signal is small. Two acoustic codes are used to find the far-field noise. Near-field propagation is computed by using Eversman's wave envelope code, which is based on a finite-element model. Propagation to the far field is accomplished by using the Kirchhoff formula for moving surfaces with the results of the wave envelope code as input data. Comparison of measured and computed far-field noise levels show fair agreement in the range of directivity angles where the peak radiation lobes from the inlet are observed. Although only a single acoustic mode is targeted in this study, the main conclusion is a proof-of-concept: Navier-Stokes codes can be used both to generate and propagate rotor-stator acoustic modes forward through an engine, where the results can be coupled to other far-field noise prediction codes.

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Section: Description Of the Unsteady Aerodynamics Codementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Ducted-Fan Engine Acoustic Predictions Using a Navier–stokes Code

Rumsey

Biedron

Farassat

et al. 1998

Journal of Sound and Vibration

View full text Add to dashboard Cite

show abstract

“…The inflow and outflow grids extended approximately 15 chord lengths upstream and downstream of the turbine respectively. The axial spacing increased with distance from the turbine to damp the amplitudes of propagating wave modes as prescribed by Rangwalla and Rai (1993). The total number of points in the grid system (shown in Figure 4) is 77,581.…”

Section: Grid Systemmentioning

confidence: 99%

Performance Improvement Through Indexing of Turbine Airfoils: Part 2 — Numerical Simulation

Griffin

Hüber

Sharma

1995

Volume 1: Turbomachinery

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An experimental/analytical study has been conducted to determine the performance improvements achievable by circumferentially indexing succeeding rows of turbine stator airfoils. A series of tests was conducted to experimentally investigate stator wake clocking effects on the performance of the space shuttle main engine (SSME) alternate turbopump development (ATD) fuel turbine test article (TTA). The results from this study indicate that significant increases in stage efficiency can be attained through application of this airfoil clocking concept. Details of the experiment and its results are documented in part 1 of this paper. In order to gain insight into the mechanisms of the performance improvement, extensive computational fluid dynamics (CFD) simulations were executed. The subject of the present paper is the initial results from the CFD investigation of the configurations and conditions detailed in part 1 of the paper. To characterize the aerodynamic environments in the experimental test series, two-dimensional (2D), time-accurate, multistage, viscous analyses were performed at the TTA midspan. Computational analyses for five different circumferential positions of the first stage stator have been completed. Details of the computational procedure and the results are presented. The analytical results verify the experimentally demonstrated performance improvement and are compared with data whenever possible. Predictions of time-averaged turbine efficiencies as well as gas conditions throughout the flow field are presented. An initial understanding of the turbine performance improvement mechanism based on the results from this investigation is described.

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“…4±8, the focus of the computations was the prediction of global aerodynamic characteristics. Rangwalla and Rai 9 compared the numerically calculated tonal acoustics with theoretical values for a two-dimensional rotor±stator interaction. Emphasis was placed on the effects of boundary conditions and boundary extent; however, the effect of the patched sliding-zone interface on the accuracy of simulating the passage of acoustic waves was not explored.…”

Section: Introductionmentioning

confidence: 98%

Computation of Acoustic Waves Through Sliding-Zone Interfaces

Rumsey

1997

AIAA Journal

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The effect of a patched sliding-zone interface on the transmission of acoustic waves is examined for two-and three-dimensional model problems. A simple but general interpolation scheme at the patched boundary passes acoustic waves without distortion, provided that a suf® ciently small time step is taken. A guideline is provided for the maximum permissible time step or zone speed that gives an acceptable error introduced by the sliding-zone interface.

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A Numerical Analysis of Tonal Acoustics in Rotor-Stator Interactions

Cited by 22 publications

References 0 publications

Ducted-Fan Engine Acoustic Predictions Using a Navier–stokes Code

Ducted-Fan Engine Acoustic Predictions Using a Navier–stokes Code

Performance Improvement Through Indexing of Turbine Airfoils: Part 2 — Numerical Simulation

Computation of Acoustic Waves Through Sliding-Zone Interfaces

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