Shape optimization of a general bypass duct for tone noise reduction using continuous adjoint method

2013 ◽  
Vol 228 (1) ◽  
pp. 119-134 ◽  
Author(s):  
S Qiu ◽  
WB Song ◽  
H Liu
Keyword(s):  
Shape Optimization ◽  
Design Problem ◽  
Adjoint Method ◽  
Finite Difference Methods ◽  
Acoustic Propagation ◽  
Low Noise ◽  
Design Tool ◽  
Propagation Model ◽  
Adjoint Formulation ◽  
Continuous Adjoint

A novel continuous adjoint-based acoustic propagation method is proposed for low-noise turbofan duct design. A fan bypass duct tonal noise propagation model that is verified by comparison with an analytical solution of the modal radiation from a semi-infinite duct with the shear layer is enhanced with its continuous adjoint formulation, having been applied to design the bypass duct. First, this article presents the complete formulation of the time-dependent optimal design problem. Second, a continuous adjoint-based acoustic propagation method for two-dimensional bypass duct configurations is derived and presented. This article aims at describing the potential of the adjoint technique for aeroacoustic shape optimization. The implementation of the unsteady aeroacoustic adjoint method is validated by comparing the sensitivity derivative with that obtained by finite differences. Using a continuous adjoint formulation, the necessary aerodynamic gradient information is obtained with large computational savings over traditional finite-difference methods. The examples presented demonstrate that the combination of a continuous-adjoint algorithm with a noise prediction method can be an efficient design tool in the bypass duct noise design problem.

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

2014 ◽  
Vol 229 (1) ◽  
pp. 69-90 ◽  
Author(s):  
S Qiu ◽  
H Liu ◽  
WP Li
Keyword(s):  
Adjoint Method ◽  
Near Field ◽  
Acoustic Propagation ◽  
Low Noise ◽  
Adjoint Equations ◽  
Nozzle Geometry ◽  
Special Treatment ◽  
Perturbation Equation ◽  
Continuous Adjoint Method ◽  
Continuous Adjoint

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.

Aerodynamic Optimization Design of Multi-stage Turbine Using the Continuous Adjoint Method

2015 ◽  
Vol 32 (2) ◽  
Author(s):  
Lei Chen ◽  
Jiang Chen
Keyword(s):  
Optimization Design ◽  
Adjoint Method ◽  
Shape Design ◽  
Aerodynamic Optimization ◽  
Aerodynamic Shape ◽  
Adjoint Formulation ◽  
Multi Stage ◽  
Continuous Adjoint Method ◽  
Continuous Adjoint

AbstractThis paper develops a continuous adjoint formulation for the aerodynamic shape design of a turbine in a multi-stage environment based on S

Design of a low noise turbofan duct via an acoustic gradient-enhanced Kriging method

2020 ◽  
pp. 095440622093364
Author(s):  
S Qiu
Keyword(s):  
Shape Optimization ◽  
Adjoint Method ◽  
Kriging Model ◽  
Low Noise ◽  
Adjoint Equations ◽  
Design Parameters ◽  
Kriging Method ◽  
Gradient Information ◽  
Design Variables ◽  
Large Numbers

The Kriging models which are frequently used in aerodynamic shape optimization may become computationally inefficient when solving problems with large numbers of design variables. One solution to this problem would be the application of gradient-enhanced Kriging model. A gradient-enhanced Kriging and acoustic adjoint-method approach to duct acoustic problems is developed, aimed to improve the efficiency and accuracy of the existing Kriging approach at acoustic problems with many design parameters. To our knowledge, it is the first application of gradient-enhanced Kriging for duct acoustic problem. It employs a Kriging response surface in the parameter space, augmented with gradients obtained from the acoustic adjoint equations efficiently. The present paper aims at describing the potential of the gradient-enhanced Kriging method for low noise turbofan duct design. Prior to the optimization process, the implementation of the unsteady aeroacoustic adjoint method in shape optimization is validated by comparing the gradient values with that obtained by finite differences. In this work, the ordinary Kriging model and gradient-enhanced Kriging method are applied firstly to a benchmark functions and the results show that the additional gradient information can significantly enhance the accuracy of Kriging model. And then, the original Kriging-based, adjoint-based and the gradient-enhanced Kriging method are all used to model 50 variable duct acoustic problems, respectively. The test results show that this approach whose gradient information is introduced by using acoustic adjoint method developed from multimode LEE, named as acoustic gradient-enhanced Kriging, can significantly enhance the accuracy of Kriging models when the gradient data are available and thus provide an optimized low noise intake while maintaining the aerodynamic performance.

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