Potential of surrogate modelling in compressor casing design focussing on rapid tip clearance assessments

2021 ◽  
Vol 125 (1291) ◽  
pp. 1587-1610
Author(s):  
T. Schmidt ◽  
V. Gümmer ◽  
M. Konle
Keyword(s):  
Finite Element ◽  
Design Space Exploration ◽  
Research Work ◽  
Axial Compressor ◽  
Surrogate Models ◽  
Tip Clearance ◽  
Fine Tuning ◽  
Computational Time ◽  
Surrogate Modelling ◽  
Aero Engine

ABSTRACTLosses induced by tip clearance limit decisive improvements in the system efficiency and aerodynamic operational stability of aero-engine axial compressors. The tendency towards even lower blade heights to compensate for higher fluid densities aggravates their influence. Generally, it is emphasised that the tip clearance should be minimised but remain large enough to prevent collisions between the blade tip and the casing throughout the entire mission. The present work concentrates on the development of a preliminary aero-engine axial compressor casing design methodology involving meta-modelling techniques. Previous research work at the Institute for Turbomachinery and Flight Propulsion resulted in a Two-Dimensional (2D) axisymmetric finite element model for a generic multi-stage high-pressure axial compressor casing. Subsequent sensitivity studies led to the identification of significant parameters that are important for fine-tuning the tip clearance via specific flange design. This work is devoted to an exploration of the potential of surrogate modelling in preliminary compressor casing design with respect to rapid tip clearance assessments and its corresponding precision in comparison with finite element results. Reputed as data-driven mathematical approximation models and conceived for inexpensive numerical simulation result reproduction, surrogate models show even greater capacity when linked with extensive design space exploration and optimisation algorithms.Compared with high-fidelity finite element simulations, the reductions obtained in computational time when using surrogate models amount to 99.9%. Validated via statistical methods and dependent on the size of the training database, the precision of surrogate models can reach down to the range of manufacturing tolerances. Subsequent inclusion of such surrogate models in a parametric optimisation process for tip clearance minimisation rapidly returned adaptions of the geometric design variables.

A Study of Large Tip Clearance Flows in an Axial Compressor Blade Row

2006 ◽  
Author(s):  
Richard Williams ◽  
David Gregory-Smith ◽  
Li He
Keyword(s):  
Research Work ◽  
Axial Compressor ◽  
Axial Direction ◽  
Low Pressure ◽  
Tip Clearance ◽  
Computational Method ◽  
Tip Clearance Flow ◽  
Clearance Flow ◽  
End Wall ◽  
Stagger Angle

The tip clearance flow of industrial axial compressor rotors has a significant impact on compressor performance. Most tip clearance flow research work has been undertaken in the earlier low-pressure transonic stages of compressors. The main differences between the earlier (low-pressure) and later (high-pressure) stages include blade profile, stagger angle, Mach number, blade length and tip clearance. The tip clearance in the later stages of an industrial axial compressor is relatively large due to mechanical constraints and short blading. The stagger angle is much lower and so the tip clearance flow is at a higher angle to the (negative) axial direction. In the present work, a computational method has been employed to investigate tip clearance flow from 1% span to 10% span for blading such as that found in the later stages. A pinch tip model is used to model the blade tip in a cascade with a stationary and moving end-wall. It has been found that the tip clearance flow rolls up into a vortex much later than in the earlier stages. The migration of the tip clearance vortex across the passage is much less than for the earlier stages and also the induced vortex is much weaker. Comparisons between a cascade with fixed and moving end-walls are made, the main difference being that the tip clearance flow is stronger with a moving end-wall. The 1% tip clearance flow structure with stationary end-wall is shown to be different from all other cases investigated.

Application of Whole Engine Finite Element Models in Aero-Engine Rotordynamic Simulation Analysis

2007 ◽  
Author(s):  
Jie Hong ◽  
Meng Chen ◽  
Shuguo Liu
Keyword(s):  
Finite Element ◽  
Rotor Dynamics ◽  
Beam Element ◽  
Dynamic Interaction ◽  
Tip Clearance ◽  
Mode Shapes ◽  
Engine Model ◽  
Solid Element ◽  
Model Based ◽  
Aero Engine

The thrust-to-weight ratio of aero-engine is increasing, the structure stiffness is reducing along with its weight, the mechanical exciting force and aerodynamic force become more and more intricate, for these reasons, dynamic interaction of different structures have to be taken into account in aero-engine vibration analysis. In traditional methods, as transfer matrix method and finite element method based on beam element, the rotor is reduced as mass point and beams, so the true dynamic interaction between the disk and shaft can’t be calculated. In this paper, MSC/NASTRAN was developed by adding the effect of gyroscopic moment to the 8 nodes solid element CHEXA with DMAP (direct matrix abstraction program) language. A rotordynamic analysis of a whole engine model based on three-dimensional (3-D) solid element was performed using the program. Firstly, an unbalance response calculation of the casing was performed to predict the translation function (dynamic stiffness) at the bearing support, as well as their effects on rotor dynamics. In the analysis of solid element models and beam element models, the effects of the coupled disks and shafts vibration as well as the corner stiffness between shafts and disks on rotor dynamics were compared, the results shown that various vibration modes could be accurately calculated using the model based on solid element. A phenomenon of the coupled rotor bending and casing vibration was captured, it was shown the third rotor critical speed of the coupled rotor bending and casing vibration mode was a frequency range. The method to predict critical speeds and mode shapes of the rotor considering dynamic interaction between the rotor and casing was investigated. Finally, a simulation platform for aero-engine dynamic analysis was set up, on which the whole engine model could be found and thermal load or aero force could be considered for different purposes. It was concluded that the true dynamic interaction between the rotor and casing as well as the disk and shaft could be captured using the whole engine model based on solid element. Further more, the foreground of the thermal and tip clearance analysis of turbine blades based on the whole engine model was discussed.

Tip Clearance Effects on Aero-elastic Stability of Axial Compressor Blades

2014 ◽  
Vol 137 (1) ◽  
Author(s):  
Zhizhong Fu ◽  
Yanrong Wang ◽  
Xianghua Jiang ◽  
Dasheng Wei
Keyword(s):  
Research Work ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Elastic Stability ◽  
Tip Clearance ◽  
Key Factors ◽  
Compressor Blades ◽  
Stable Case ◽  
Aerodynamic Damping ◽  
Compressor Rotor

The tip clearance effects on aero-elastic stability of axial compressor blades are investigated with two independent three-dimensional (3D) flutter prediction approaches: energy method and aero-elastic eigenvalue analysis. An axial compressor rotor which has encountered broken fault caused by flutter during the test rig and flight has been analyzed for five tip gap configurations. A consistent conclusion obtained by these two independent approaches shows the variation trend of aerodynamic damping is not monotonic, but aerodynamic damping at the least stable case shows a trend of first decrease and then increase with the rising of tip gap size, which is different from the results of other researchers and can be utilized to understand the conflict between the conclusions of different research work. Apart from the results of tip clearance effects on aero-elastic stability, the employed two methods have revealed the key factors involved in the flutter occurrence from a different perspective.

Improving the Computational Cost for Copied Region Detection in Forensic Images

2016 ◽  
Vol 2 (1) ◽  
pp. 55
Author(s):  
Tu Huynh-Kha ◽  
Thuong Le-Tien ◽  
Synh Ha ◽  
Khoa Huynh-Van
Keyword(s):  
Wavelet Transform ◽  
Euclidean Distance ◽  
Research Work ◽  
Computational Cost ◽  
Correlation Coefficients ◽  
Zernike Moments ◽  
Computational Time ◽  
Discrete Wavelet ◽  
Feature Vectors ◽  
Region Detection

This research work develops a new method to detect the forgery in image by combining the Wavelet transform and modified Zernike Moments (MZMs) in which the features are defined from more pixels than in traditional Zernike Moments. The tested image is firstly converted to grayscale and applied one level Discrete Wavelet Transform (DWT) to reduce the size of image by a half in both sides. The approximation sub-band (LL), which is used for processing, is then divided into overlapping blocks and modified Zernike moments are calculated in each block as feature vectors. More pixels are considered, more sufficient features are extracted. Lexicographical sorting and correlation coefficients computation on feature vectors are next steps to find the similar blocks. The purpose of applying DWT to reduce the dimension of the image before using Zernike moments with updated coefficients is to improve the computational time and increase exactness in detection. Copied or duplicated parts will be detected as traces of copy-move forgery manipulation based on a threshold of correlation coefficients and confirmed exactly from the constraint of Euclidean distance. Comparisons results between proposed method and related ones prove the feasibility and efficiency of the proposed algorithm.

The prediction of vehicle vibration transmitted to the occupant using a modular transfer matrix

2021 ◽  
pp. 107754632199759
Author(s):  
Jianchun Yao ◽  
Mohammad Fard ◽  
John L Davy ◽  
Kazuhito Kato
Keyword(s):  
Finite Element ◽  
Transfer Matrix ◽  
Dynamic Performance ◽  
Complex Structure ◽  
Vehicle Body ◽  
Computational Time ◽  
Accurate Estimation ◽  
Finite Element Models ◽  
Transfer Matrices ◽  
Body Vibration

Industry is moving towards more data-oriented design and analyses to solve complex analytical problems. Solving complex and large finite element models is still challenging and requires high computational time and resources. Here, a modular method is presented to predict the transmission of vehicle body vibration to the occupants’ body by combining the numerical transfer matrices of the subsystems. The transfer matrices of the subsystems are presented in the form of data which is sourced from either physical tests or finite element models. The structural dynamics of the vehicle body is represented using a transfer matrix at each of the seat mounting points in three triaxial (X–Y–Z) orientations. The proposed method provides an accurate estimation of the transmission of the vehicle body vibration to the seat frame and the seated occupant. This method allows the combination of conventional finite element analytical model data and the experimental data of subsystems to accurately predict the dynamic performance of the complex structure. The numerical transfer matrices can also be the subject of machine learning for various applications such as for the prediction of the vibration discomfort of the occupant with different seat and foam designs and with different physical characteristics of the occupant body.

scholarly journals Stiffness Estimation and Equivalence of Boundary Conditions in FEM Models

2021 ◽  
Vol 11 (4) ◽  
pp. 1482
Author(s):  
Róbert Huňady ◽  
Pavol Lengvarský ◽  
Peter Pavelka ◽  
Adam Kaľavský ◽  
Jakub Mlotek
Keyword(s):  
Boundary Condition ◽  
Finite Element ◽  
Boundary Conditions ◽  
Model Updating ◽  
Element Model ◽  
Computational Time ◽  
Stiffness Coefficients ◽  
First Case ◽  
Numerical Approaches

The paper deals with methods of equivalence of boundary conditions in finite element models that are based on finite element model updating technique. The proposed methods are based on the determination of the stiffness parameters in the section plate or region, where the boundary condition or the removed part of the model is replaced by the bushing connector. Two methods for determining its elastic properties are described. In the first case, the stiffness coefficients are determined by a series of static finite element analyses that are used to obtain the response of the removed part to the six basic types of loads. The second method is a combination of experimental and numerical approaches. The natural frequencies obtained by the measurement are used in finite element (FE) optimization, in which the response of the model is tuned by changing the stiffness coefficients of the bushing. Both methods provide a good estimate of the stiffness at the region where the model is replaced by an equivalent boundary condition. This increases the accuracy of the numerical model and also saves computational time and capacity due to element reduction.

scholarly journals Image-based semi-multiscale finite element analysis using elastic subdomain homogenization

Meccanica ◽  
2021 ◽  
Author(s):  
J. Jansson ◽  
K. Salomonsson ◽  
J. Olofsson
Keyword(s):  
Finite Element ◽  
Analytical Method ◽  
Effective Properties ◽  
Reference Model ◽  
Computational Time ◽  
Component Level ◽  
Element Analysis ◽  
Model Fidelity ◽  
Multiscale Finite Element ◽  
Anisotropic Elastic

AbstractIn this paper we present a semi-multiscale methodology, where a micrograph is split into multiple independent numerical model subdomains. The purpose of this approach is to enable a controlled reduction in model fidelity at the microscale, while providing more detailed material data for component level- or more advanced finite element models. The effective anisotropic elastic properties of each subdomain are computed using periodic boundary conditions, and are subsequently mapped back to a reduced mesh of the original micrograph. Alternatively, effective isotropic properties are generated using a semi-analytical method, based on averaged Hashin–Shtrikman bounds with fractions determined via pixel summation. The chosen discretization strategy (pixelwise or partially smoothed) is shown to introduce an uncertainty in effective properties lower than 2% for the edge-case of a finite plate containing a circular hole. The methodology is applied to a aluminium alloy micrograph. It is shown that the number of elements in the aluminium model can be reduced by $$99.89\%$$ 99.89 % while not deviating from the reference model effective material properties by more than $$0.65\%$$ 0.65 % , while also retaining some of the characteristics of the stress-field. The computational time of the semi-analytical method is shown to be several orders of magnitude lower than the numerical one.

scholarly journals Practical Prediction of the Boil-Off Rate of Independent-Type Storage Tanks

2021 ◽  
Vol 9 (1) ◽  
pp. 36
Author(s):  
Dong-Ha Lee ◽  
Seung-Joo Cha ◽  
Jeong-Dae Kim ◽  
Jeong-Hyeon Kim ◽  
Seul-Kee Kim ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Environmentally Friendly ◽  
Fuel Tank ◽  
Computational Time ◽  
Insulation Material ◽  
Element Analysis ◽  
Vertical Temperature Profile ◽  
Space Efficiency ◽  
Key Aspects

Because environmentally-friendly fuels such as natural gas and hydrogen are primarily stored in the form of cryogenic liquids to enable efficient transportation, the demand for cryogenic fuel (LNG, LH) ships has been increasing as the primary carriers of environmentally-friendly fuels. In such ships, insulation systems must be used to prevent heat inflow to the tank to suppress the generation of boil-off gas (BOG). The presence of BOG can lead to an increased internal pressure, and thus, its control and prediction are key aspects in the design of fuel tanks. In this regard, although the thermal analysis of the phase change through a finite element analysis requires less computational time than that implemented through computational fluid dynamics, the former is relatively more error-prone. Therefore, in this study, a cryogenic fuel tank to be incorporated in ships was established, and the boil-off rate (BOR), measured considering liquid nitrogen, was compared with that obtained using the finite element method. Insulation material with a cubic structure was applied to the cylindrical tank to increase the insulation performance and space efficiency. To predict the BOR through finite element analysis, the effective thermal conductivity was calculated through an empirical correlation and applied to the designed fuel tank. The calculation was predicted to within 1% of the minimum error, and the internal fluid behavior was evaluated by analyzing the vertical temperature profile according to the filling ratio.

scholarly journals Application of micro-computer tomography and inverse finite element analysis for characterizing the visco-hyperelastic response of bulk liver tissue using indentation

2021 ◽  
Vol 3 (5) ◽  
Author(s):  
Rajeswara R. Resapu ◽  
Roger D. Bradshaw
Keyword(s):  
Finite Element ◽  
Liver Tissue ◽  
Loading Rate ◽  
Time Dependent ◽  
Nonlinear Material ◽  
Computational Time ◽  
List Type ◽  
Prony Series ◽  
Time Dependent Behaviour ◽  
Dependent Behaviour

Abstract In-vitro mechanical indentation experimentation is performed on bulk liver tissue of lamb to characterize its nonlinear material behaviour. The material response is characterized by a visco-hyperelastic material model by the use of 2-dimensional inverse finite element (FE) analysis. The time-dependent behaviour is characterized by the viscoelastic model represented by a 4-parameter Prony series, whereas the large deformations are modelled using the hyperelastic Neo-Hookean model. The shear response described by the initial and final shear moduli and the corresponding Prony series parameters are optimized using ANSYS with the Root Mean Square (RMS) error being the objective function. Optimized material properties are validated using experimental results obtained under different loading histories. To study the efficacy of a 2D model, a three dimensional (3D) model of the specimen is developed using Micro-CT of the specimen. The initial elastic modulus of the lamb liver obtained was found to 13.5 kPa for 5% indentation depth at a loading rate of 1 mm/sec for 1-cycle. These properties are able to predict the response at 8.33% depth and a loading rate of 5 mm/sec at multiple cycles with reasonable accuracy. Article highlights The visco-hyperelastic model accurately models the large displacement as well as the time-dependent behaviour of the bulk liver tissue. Mapped meshing of the 3D FE model saves computational time and captures localized displacement in an accurate manner. The 2D axisymmetric model while predicting the force response of the bulk tissue, cannot predict the localized deformations.

Modal Analysis of the Axial Compressor Blade: Advanced Time-Dependent Electronic Interferometry and Finite Element Method

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Mykhaylo Tkach ◽  
Serhii Morhun ◽  
Yuri Zolotoy ◽  
Irina Zhuk
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Finite Element ◽  
High Reliability ◽  
Axial Compressor ◽  
Time Dependent ◽  
Experimental Setup ◽  
Vibration Modes ◽  
Compressor Blades ◽  
Isoparametric Finite Element

AbstractNatural frequencies and vibration modes of axial compressor blades are investigated. A refined mathematical model based on the usage of an eight-nodal curvilinear isoparametric finite element was applied. The verification of the model is carried out by finding the frequencies and vibration modes of a smooth cylindrical shell and comparing them with experimental data. A high-precision experimental setup based on an advanced method of time-dependent electronic interferometry was developed for this aim. Thus, the objective of the study is to verify the adequacy of the refined mathematical model by means of the advanced time-dependent electronic interferometry experimental method. The divergence of the results of frequency measurements between numerical calculations and experimental data does not exceed 5 % that indicates the adequacy and high reliability of the developed mathematical model. The developed mathematical model and experimental setup can be used later in the study of blades with more complex geometric and strength characteristics or in cases when the real boundary conditions or mechanical characteristics of material are uncertain.

Sign in / Sign up

Export Citation Format

Share Document