Design of Optimum Acoustic Treatment for Rectangular Ducts With Flow

Motsinger, R. E.; Kraft, R. E.; Zwick, J.W.

doi:10.1115/76-gt-113

Cited by 13 publications

(12 citation statements)

References 3 publications

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“…Current emphasis is on the optimization of wall treatment alone to minimize aerodynamic losses and weight penalties in aircraft applications. The attenuation achieved is very sensitive to the source modal characteristics used as input (78,79). Input cases of interest range from a limited number of modes associated with tone noise from periodic blade row interactions, to multi-modal situations associated with random processes exciting all the modes the duct can support.…”

Section: Exhaust Radiationmentioning

confidence: 99%

Aircraft Turbofan Noise

Groeneweg

Rice

1983

Volume 5: Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; Process Industries

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Recent advances in the understanding of turbofan noise generation and suppression in aircraft engines are reviewed with particular emphasis on NASA research. The review addresses each link in the chain of physical processes which connect unsteady flow interactions with fan blades to far field noise. Mechanism identification and description, duct propagation, radiation and acoustic suppression are discussed. Recent advances in the experimental technique of fan inflow control assure that in-flight generation mechanisms are not ma.,ked by extraneous sources in static tests. Rotor blade surface pressure and wake velocity measurements aid the determination of the types and strengths of the generation mechanisms. Approaches to predicting or measuring acoustic mode content, optimizing treatment impedance to maximize attenuation, translating impedance into porous wall structure and interpreting far field directivity patterns are illustrated by comparisons of analytical and experimental results. A persistent theme of the review is the interdependence of source and acoustic treatment design to minimize far field noise. Areas requiring further research are discussed and the relevance of aircraft turbofan results to quieting other turbomachinery installations is addressed.

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Section: Exhaust Radiationmentioning

confidence: 99%

Aircraft Turbofan Noise

Groeneweg

Rice

1983

Volume 5: Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education; Process Industries

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“…A lot of work on acoustic liner optimization had been done by researchers to reduce the propagation of turbomachinery noise in the ducted regions of turbofan engines. [16][17][18][19][20][21][22][23][24] On the other hand, optimized the geometry of intake is the other effective way to control the fan noise by adjusting the propagation paths of fan noise. The basic idea of the intake shape optimization is to minimize the far field acoustic radiation by controlling the geometry of an engine duct.…”

Section: Introductionmentioning

confidence: 99%

A continuous adjoint-based aeroacoustic shape optimization for multi-mode duct acoustics

Qiu¹

2017

Proceedings of the Institution of Mechanical Engineers, Part C:

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A multi-mode adjoint-based optimization method is proposed for the noise reduction optimization in multi-mode duct acoustics problems. The objective is to minimize the amplitude of sound from an inlet duct on the wall and integral line while maintaining the aerodynamic performance. The complete detailed derivation of the adjoint equations and their corresponding adjoint boundary conditions are presented firstly based on the multi-mode linear Euler equations. With the solved adjoint variables, the final expression of the cost function gradient with respect to the design variables is formulated. The sensitivity derivative computed by the continuous adjoint method is validated by comparing with that obtained using finite difference method. Up to 50 design variables are involved in the adjoint optimization to ensurely provide an adequate design space. And a quasi-Newton Broyden–Fletcher–Goldfarb–Shanno algorithm is utilized to determine an improved intake duct geometry based on the objective function gradient provided by the adjoint solution. Finally, two multi-mode optimization of a typical inlet duct confirms the flexibility of the multi-mode adjoint-based framework and the efficiency of the multi-mode adjoint-based technique.

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“…An effective way of reducing aero-engine noise is by using acoustic liners. [14][15][16][17][18] Due to weight limits, it has become difficult to achieve further noise reduction by acoustic liners. An alternative technology being considered in recent years is to optimize the shape of turbofan duct.…”

Section: Introductionmentioning

confidence: 99%

Turbofan duct geometry optimization for low noise using remote continuous adjoint method

Qiu

Liu

2014

Proceedings of the Institution of Mechanical Engineers, Part C:

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In this paper, a remote continuous adjoint-based acoustic propagation (RABAP) method is proposed for low noise turbofan duct design. The goal is to develop a set of adjoint equations and their corresponding boundary conditions in order to quantify the influence of geometry modifications on the amplitude of sound pressure at a near-field location. The governing equations for the 2.5D acoustic perturbation equation solver (APE) formulation for duct acoustic propagation is first introduced. This is followed by the formulation and discretization of the remote continuous adjoint equations based on 2.5D APE. The special treatment of the adjoint boundary condition to obtain sensitivities derivatives is also discussed. The theory is applied to acoustic design of an axisymmetric fan bypass duct for two different tone noise radiations. The 2.5D APE is further validated using comparisons to an experiment data of the TURNEX nozzle geometry. The implementation of the remote continuous adjoint method is validated by comparing the sensitivity derivative with that obtained using finite difference method. The result obtained confirms the effectiveness and efficiency of the proposed RABAP framework.

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Design of Optimum Acoustic Treatment for Rectangular Ducts With Flow

Cited by 13 publications

References 3 publications

Aircraft Turbofan Noise

Aircraft Turbofan Noise

A continuous adjoint-based aeroacoustic shape optimization for multi-mode duct acoustics

Turbofan duct geometry optimization for low noise using remote continuous adjoint method

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