Adjoint-Based Inverse Design of Axial Compressor Airfoils

2021 ◽  
Author(s):  
Christophe Geuens ◽  
Tom Verstraete
Keyword(s):  
Inverse Problem ◽  
Inverse Method ◽  
Axial Compressor ◽  
Direct Methods ◽  
Velocity Profiles ◽  
Inverse Methods ◽  
Design Methods ◽  
Operating Conditions ◽  
Inverse Design ◽  
Blade Shape

Abstract Design methodologies for axial compressor airfoils have undergone significant changes over the past decades. While inverse design methods have played a significant historical role, today they are mostly replaced by direct methods. Inverse methods do impose either the desired pressure or velocity distribution and search for the corresponding blade profile, in contrast to direct methods which modify directly the blade shape to reduce losses. Inverse methods therefore require the designer to know pressure or velocity profiles which provide low losses, and are as such mostly effective only in the hands of an experienced designer. Inverse methods, however, pose some advantages: through setting velocity profiles which feature good off-design performance, the computational cost for the design of profiles can be significantly reduced compared to direct methods, which require to simulate multiple operating points. Additionally, inverse methods offer a way to adapt blades for experimental testing if the wind tunnel imposes restrictions on e.g. Mach number, allowing for similar boundary layer conditions. Finally, inverse methods can be used to deduce the blade geometry from measured or published velocity distributions. Within this article, we aim to verify the use of inverse methods by applying more recent optimisation techniques to the inverse problem. Specifically, we test the performance of an inverse method that uses a gradient based technique to solve the inverse problem. The merits of the inverse method are investigated for different use cases. It is found that conventional, direct design methods are preferred for design improvement, although more expensive. The inverse method is, however, well-suited for adapting existing profiles to altered operating conditions, and for reproducing the blade shape based on published data.

Cold Blade Profile Generation Methodology for Compressor Rotor Blades Using FSI Approach

2017 ◽  
Author(s):  
Kirubakaran Purushothaman ◽  
Sankar Kumar Jeyaraman ◽  
Ajay Pratap ◽  
Kishore Prasad Deshkulkarni
Keyword(s):  
Aspect Ratio ◽  
Rotor Blade ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Rotor Blades ◽  
Blade Profile ◽  
Interaction Technique ◽  
Compressor Rotor ◽  
Blade Shape ◽  
Blade Geometry

This paper describes a methodology for obtaining correct blade geometry of high aspect ratio axial compressor blades during running condition taking into account of blade untwist and bending. It discusses the detailed approach for generating cold blade geometry for axial compressor rotor blades from the design blade geometry using fluid structure interaction technique. Cold blade geometry represents the rotor blade shape at rest, which under running condition deflects and takes a new operating blade shape under centrifugal and aerodynamic loads. Aerodynamic performance of compressor primarily depends on this operating rotor blade shape. At design point it is expected to have the operating blade shape same as the intended design blade geometry and a slight mismatch will result in severe performance deterioration. Starting from design blade profile, an appropriate cold blade profile is generated by applying proper lean and pre-twist calculated using this methodology. Further improvements were carried out to arrive at the cold blade profile to match the stagger of design profile at design operating conditions with lower deflection and stress for first stage rotor blade. In rear stages, thermal effects will contribute more towards blade deflection values. But due to short blade span, deflection and untwist values will be of lower values. Hence difference between cold blade and design blade profile would be small. This methodology can especially be used for front stage compressor rotor blades for which aspect ratio is higher and deflections are large.

On the Coupling of Inverse Design and Optimization Techniques for Turbomachinery Blade Design

2006 ◽  
Author(s):  
Duccio Bonaiuti ◽  
Mehrdad Zangeneh
Keyword(s):  
Mechanical Design ◽  
Design Method ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Optimization Techniques ◽  
Operating Conditions ◽  
Inverse Design ◽  
Design Parameters ◽  
Optimization Strategy ◽  
Design And Optimization

Optimization strategies have been used in recent years for the aerodynamic and mechanical design of turbomachine components. One crucial aspect in the use of such methodologies is the choice of the geometrical parameterization, which determines the complexity of the objective function to be optimized. In the present paper, an optimization strategy for the aerodynamic design of turbomachines is presented, where the blade parameterization is based on the use of a three-dimensional inverse design method. The blade geometry is described by means of aerodynamic parameters, like the blade loading, which are closely related to the aerodynamic performance to be optimized, thus leading to a simple shape of the optimization function. On the basis of this consideration, it is possible to use simple approximation functions for describing the correlations between the input design parameters and the performance ones. The Response Surface Methodology coupled with the Design of Experiments (DOE) technique was used for this purpose. CFD analyses were run to evaluate the configurations required by the DOE to generate the database. Optimization algorithms were then applied to the approximated functions in order to determine the optimal configuration or the set of optimal ones (Pareto front). The method was applied for the aerodynamic redesign of two different turbomachine components: a centrifugal compressor stage and a single-stage axial compressor. In both cases, both design and off-design operating conditions were analyzed and optimized.

scholarly journals Inverse Method of Centrifugal Pump Blade Based on Gaussian Process Regression

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Renhui Zhang ◽  
Xutao Zhao
Keyword(s):  
Inverse Problem ◽  
Gaussian Process ◽  
Centrifugal Pump ◽  
Cross Validation ◽  
Gaussian Process Regression ◽  
Inverse Methods ◽  
Shape Parameters ◽  
Problem Model ◽  
Blade Shape ◽  
Mean Square Errors

The inverse problem is always one of the important issues in the field of fluid machinery for the complex relationship among the blade shape, the hydraulic performance, and the inner flow structure. Based on Bayesian theory of posterior probability obtained from known prior probability, the inverse methods for the centrifugal pump blade based on the single-output Gaussian process regression (SOGPR) and the multioutput Gaussian process regression (MOGPR) were proposed, respectively. The training sample set consists of the blade shape parameters and the distribution of flow parameters. The hyperparameters in the inverse problem models were trained by using the maximum likelihood estimation and the gradient descent algorithm. The blade shape corresponding to the objective blade load can be achieved by the trained inverse problem models. The MH48-12.5 low specific speed centrifugal pump was selected to verify the proposed inverse methods. The reliability and accuracy of both inverse problem models were confirmed and compared by implementing leave-one-out (LOO) cross-validation and extrapolation characteristic analysis. The results show that the blade shapes within the sample space can be reconstructed exactly by both models. The root mean square errors of the MOGPR inverse problem model for the pump blade are generally lower than those of the SOGPR inverse problem model in the LOO cross-validation. The extrapolation characteristic of the MOGPR inverse problem model is better than that of the SOGPR inverse problem model for the correlation between the blade shape parameters can be fully considered by the correlation matrix of the MOGPR model. The proposed inverse methods can efficiently solve the inverse problem of centrifugal pump blade with sufficient accuracy.

Inverse Design of Radial Compressor Components by Modern CFD

2000 ◽  
Author(s):  
R. A. Van den Braembussche ◽  
J. Antolin ◽  
R. Thygesen
Keyword(s):  
Velocity Distribution ◽  
Inverse Method ◽  
Three Dimensional ◽  
Inverse Methods ◽  
Inverse Design ◽  
Centrifugal Impeller ◽  
Design Criteria ◽  
Radial Compressor ◽  
Inlet Guide Vanes ◽  
Return Channel

Abstract The use of a three-dimensional inverse method for the design of inlet guide vanes, a centrifugal impeller and return channel is demonstrated. The geometry of the different components are iteratively defined until a prescribed velocity distribution is obtained. The procedure and design criteria for each component are described and the final result is presented. The advantages, disadvantages and problems related to the use of inverse methods are discussed.

3D Viscous Inverse Design of Turbomachinery Using One-Equation Turbulence Model

2016 ◽  
Author(s):  
Jinguang Yang ◽  
Yan Liu ◽  
Xiaofang Wang ◽  
Hu Wu
Keyword(s):  
Turbulence Model ◽  
Inverse Method ◽  
Turbulence Models ◽  
Search Method ◽  
Exhaustive Search ◽  
Inverse Design ◽  
Target Point ◽  
Distance Calculation ◽  
Wall Distance ◽  
Blade Shape

Inverse method is a very efficient method in turbomachinery aerodynamic design. It takes blade aerodynamic loading as input, and the blade shape and the flow field are computed when calculation converged. However most current inverse methods model turbulent eddy viscosity by Baldwin-Lomax (BL) model or similar approximation, which does not involve local wall distance as a model parameter. Most one- and two-equation turbulence models are not that case, and local wall distance is needed in turbulent work variable(s) transport equation formulation. The usual wall distance computing procedure is the so called “exhaustive search method”, which is a time-consuming process. When a flow solver running in analysis mode, the wall distance calculation is not a problem, it can be computed once and stored for subsequent use. But for design mode, this computation intensive process becomes a big challenge. For an inverse design run, the blade shape is updated periodically for about 400 times, if wall distances is re-computed for each blade shape update, the time cost is very appreciable. That is the reason that prohibits the application of higher order (one- and two-equation, compared to BL model) turbulence models in inverse method. In this paper, a novel wall distance calculation method is proposed. The new method transforms the distance searching problem into a length optimization problem, and the steepest descent method is used to find the minimal length from a target point to a wall face. Numerical experiments show that the method can reduce the computing time to approximately 1/10 of the exhaustive search method. Based on this, together with an enhanced blade update method and Spalart-Allmaras turbulence model, a 3D viscous redesign of an axial fan rotor is conducted. Final results demonstrate the effectivity of the proposed method.

scholarly journals Phase-to-pattern inverse design paradigm for fast realization of functional metasurfaces via transfer learning

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Ruichao Zhu ◽  
Tianshuo Qiu ◽  
Jiafu Wang ◽  
Sai Sui ◽  
Chenglong Hao ◽  
...  
Keyword(s):  
Transfer Learning ◽  
Electromagnetic Waves ◽  
Inverse Method ◽  
Inverse Design ◽  
Learning Network ◽  
Design Paradigm ◽  
Simulation And Experiment ◽  
Meta Atom ◽  
Trained Network ◽  
Input Phase

AbstractMetasurfaces have provided unprecedented freedom for manipulating electromagnetic waves. In metasurface design, massive meta-atoms have to be optimized to produce the desired phase profiles, which is time-consuming and sometimes prohibitive. In this paper, we propose a fast accurate inverse method of designing functional metasurfaces based on transfer learning, which can generate metasurface patterns monolithically from input phase profiles for specific functions. A transfer learning network based on GoogLeNet-Inception-V3 can predict the phases of 28×8 meta-atoms with an accuracy of around 90%. This method is validated via functional metasurface design using the trained network. Metasurface patterns are generated monolithically for achieving two typical functionals, 2D focusing and abnormal reflection. Both simulation and experiment verify the high design accuracy. This method provides an inverse design paradigm for fast functional metasurface design, and can be readily used to establish a meta-atom library with full phase span.

Comparative Life Cycle Assessment of Different Gas Turbine Axial Compressor Water Washing Systems

2020 ◽  
Author(s):  
Ilaria Dominizi ◽  
Serena Gabriele ◽  
Angela Serra ◽  
Domenico Borello
Keyword(s):  
Life Cycle Assessment ◽  
Life Cycle ◽  
Gas Turbine ◽  
Axial Compressor ◽  
Operating Conditions ◽  
Energy Field ◽  
Water Washing ◽  
Before And After ◽  
Reduce Emissions ◽  
Global Threat

Abstract Nowadays the climate change is widely recognized as a global threat by both public opinion and industries. Actions to mitigate its causes are gaining momentum within all industries. In the energy field, there is the necessity to reduce emissions and to improve technologies to preserve the environment. LCA analyses of products are fundamental in this context. In the present work, a life cycle assessment has been carried out to calculate the carbon footprint of different water washing processes, as well as their effectiveness in recovering Gas Turbine efficiency losses. Field data have been collected and analyzed to make a comparison of the GT operating conditions before and after the introduction of an innovative high flow online water washing technique. The assessments have been performed using SimaPro software and cover the entire Gas Turbine and Water Washing skids operations, including the airborne emissions, skid pump, the water treatment and the heaters.

scholarly journals Effectiveness Testing of an Inverse Method for Balancing Nonlinear Rotordynamic Systems

2018 ◽  
Author(s):  
Sergio G. Torres Cedillo ◽  
Philip Bonello ◽  
Ghaith Ghanim Al-Ghazal ◽  
Jacinto Cortés Pérez ◽  
Alberto Reyes Solis
Keyword(s):  
Inverse Problem ◽  
Inverse Method ◽  
Linear Connection ◽  
The Other ◽  
Squeeze Film ◽  
Squeeze Film Damper ◽  
Operational Conditions ◽  
Non Invasive ◽  
Highly Nonlinear ◽  
Aero Engine

Modern aero-engine structures typically have at least two nested rotors mounted within a flexible casing via squeeze-film damper (SFD) bearings. The inaccessibility of the HP rotor under operational conditions motivates the use of a non-invasive inverse problem procedure for identifying the unbalance. Such an inverse problem requires prior knowledge of the structure and measurements of the vibrations at the casing. Recent work by the authors reported a non-invasive inverse method for the balancing of rotordynamic systems with nonlinear squeeze-film damper (SFD) bearings, which overcomes several limitations of earlier works. However, it was not applied to a common practical configuration wherein the HP rotor is mounted on the casing via just one weak linear connection (retainer spring), with the other connections being highly nonlinear SFDs. The analysis of the present paper considers such a system. It explores the influence of the condition number and how it is affected as the number of sensors and/or measurement speeds is increased. The results show that increasing the number of measurement speeds has a far more significant impact on the conditioning of the problem than increasing the number of sensors. The balancing effectiveness is reasonably good under practical noise level conditions, but significantly lower than obtained for the previously considered simpler configurations.

A New Loss and Deviation Model for Axial Compressor Inlet Guide Vanes

2013 ◽  
Author(s):  
Milan Banjac ◽  
Milan V. Petrovic ◽  
Alexander Wiedermann
Keyword(s):  
Guide Vane ◽  
Thickness Distribution ◽  
Axial Compressor ◽  
Algebraic Model ◽  
Operating Conditions ◽  
Inlet Guide Vane ◽  
Viscous Effects ◽  
Through Flow ◽  
Trailing Vortices ◽  
Compressor Inlet

This paper describes a new universal algebraic model for the estimation of flow deflection and losses in axial compressor inlet guide vane devices. The model deals with nominal flow and far-off-design operating conditions in connection with large stagger angle adjustments. The first part of the model considers deflection and losses in 2D cascades, taking into account the main cascade geometry parameters and operating conditions, such as Mach number and stagger adjustment. The second part of the model deals with additional deviation and losses due to secondary flow caused by the endwall viscous effects and by the trailing vortices. The model is developed for NACA65 airfoils, NACA63-A4K6 airfoils and airfoils having an NACA65 thickness distribution on a circular-arc camber line. It is suitable for application in 1D or 2D through-flow calculations for design and analysis cases. The development of the method is based on systematic CFD flow calculations for various cascade geometries and operating parameters. The comparison of correlation results with experimental data for several test cases shows good agreement.

Sign in / Sign up

Export Citation Format

Share Document