Probabilistic Finite Element Analysis of Cooled High-Pressure Turbine Blades—Part A: Holistic Description of Manufacturing Variability

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger

Abstract Modern high-pressure turbine (HPT) blade design stands out due to its high complexity comprising three-dimensional blade features, multipassage cooling system (MPCS), and film cooling to allow for progressive thermodynamic process parameters. During the last decade, probabilistic design approaches have become increasingly important in turbomachinery to incorporate uncertainties such as geometric variations caused by manufacturing scatter and deterioration. Within this scope, the first part of this two-part article introduces parametric models for cooled turbine blades that enable probabilistic finite element (FE) analysis taking geometric variability into account to aim at sensitivity and robustness evaluation. The statistical database is represented by a population of more than 400 blades whose external geometry is captured by optical measurement techniques and 34 blades that are digitized by computed tomography (CT) to record the internal geometry and the associated variability, respectively. Based on these data, parametric models for airfoil, profiled endwall (PEW), wedge surface (WSF), and MPCS are presented. The parametric airfoil model that is based on the traditional profile theory is briefly described. In this regard, a methodology is presented that enables to adapt this airfoil model to a given population of blades by means of Monte Carlo-based optimization. The endwall variability of hub and shroud are parametrized by radial offsets that are applied to the respective median endwall geometry. WSFs are analytically represented by planes. Variations of the MPCS are quantified based on the radial distribution of cooling passage centroids. Thus, an individual MPCS can be replicated by applying adapted displacement functions to the core passage centroids. For each feature that is considered within this study, the accuracy of the parametric model is discussed with respect to the variability that is present in the investigated blade population and the measurement uncertainty. Within the scope of the second part of this article, the parametric models are used for a comprehensive statistical analysis to reveal the parameter correlation structure and probability density functions (PDFs). This is required for the subsequent probabilistic finite element analysis involving real geometry effects.

Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger

Abstract Modern high pressure turbine (HPT) blade design stands out due to its high complexity comprising three-dimensional blade features, multi-passage cooling system (MPCS) and film cooling to allow for progressive thermodynamic process parameters. During the last decade, probabilistic design approaches have become increasingly important in turbomachinery to incorporate uncertainties such as geometric variations caused by manufacturing scatter and deterioration. Within this scope, the first part of this two-part paper introduces parametric models for cooled turbine blades that enable probabilistic FE analysis taking geometric variability into account to aim at sensitivity and robustness evaluation. The statistical database is represented by a population of more than 400 blades whose external geometry is captured by optical measurement techniques and 34 blades that are digitized by computed tomography (CT) to record the internal geometry and the associated variability, respectively. Based on this data, parametric models for airfoil, profiled endwall (PEW), wedge surface (WSF) and MPCS are presented. The parametric airfoil model which is based on traditional profile theory is briefly described. In this regard, a methodology is presented that enables to adapt this airfoil model to a given population of blades by means of Monte-Carlo based optimization. The endwall variability of hub and shroud are parametrized by radial offsets that are applied to the respective median endwall geometry. WSFs are analytically represented by planes. Variations of the MPCS are quantified based on the radial distribution of cooling passage centroids. Thus, an individual MPCS can be replicated by applying adapted displacement functions to the core passage centroids. For each feature that is considered within the present study, the accuracy of the parametric model is discussed with respect to the variability that is present in the investigated blade population and the measurement uncertainty. Within the scope of the second part of this paper (cf. Högner et al. [1]), the parametric models are used for a comprehensive statistical analysis to reveal the parameter correlation structure and probability density functions (PDFs). This is required for the subsequent probabilistic finite element analysis involving real geometry effects.


Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger

Abstract Modern high pressure turbine (HPT) blade design stands out due to high complexity comprising three-dimensional blade features, multi-passage cooling system (MPCS) and film cooling to allow for progressive thermodynamic process parameters. During the last decade, probabilistic design approaches have become increasingly important in turbomachinery to incorporate uncertainties such as geometric variations caused by manufacturing scatter. In part B of this two-part paper, real geometry effects are considered within a probabilistic finite element (FE) analysis that aims at sensitivity evaluation. The knowledge about the geometric variability is derived based on a blade population of more than 400 individuals by means of parametric models that are introduced in part A (cf. Högner et al. [1]). The HPT blade population is statistically assessed which allows for reliable sensitivity analysis and robustness evaluation taking the variability of the airfoil, profiled endwalls (PEW) at hub and shroud, wedge surfaces (WSF) and the MPCS into account. The probabilistic method — Monte-Carlo simulation (MCS) using an extended Latin Hypercube Sampling (eLHS) technique — is presented subsequently. Afterwards, the FE model that involves thermal, linear-elastic stress and creep analysis is described briefly. Based on this, the fully automated process chain involving CAD model creation, FE mesh morphing, FE analysis and post-processing is executed. Here, the mesh morphing process is presented involving a discussion of the mesh quality. The process robustness is assessed and quantified referring to the impact on input parameter correlation. Finally, the result quantities of the probabilistic FE simulation are evaluated in terms of sensitivities. For this purpose, regions of interest are determined, wherein the statistical analysis is conducted to achieve the sensitivity ranking. A significant influence of the considered geometric uncertainties onto mechanical output quantities is observed which motivates to incorporate these in modern design strategies or robust optimization.


2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger

Abstract Modern high-pressure turbine (HPT) blade design stands out due to high complexity comprising three-dimensional blade features, multipassage cooling system (MPCS), and film cooling to allow for progressive thermodynamic process parameters. During the last decade, probabilistic design approaches have become increasingly important in turbomachinery to incorporate uncertainties such as geometric variations caused by manufacturing scatter. In Part B of this two-part article, real geometry effects are considered within a probabilistic finite element (FE) analysis that aims at sensitivity evaluation. The knowledge about the geometric variability is derived based on a blade population of more than 400 individuals by means of parametric models that are introduced in Part A. The HPT blade population is statistically assessed, which allows for reliable sensitivity analysis and robustness evaluation taking the variability of the airfoil, profiled endwalls (PEWs) at hub and shroud, wedge surfaces (WSFs), and the MPCS into account. The probabilistic method—Monte Carlo simulation (MCS) using an extended Latin hypercube sampling (eLHS) technique—is presented subsequently. Afterward, the FE model that involves thermal, linear-elastic stress, and creep analysis is described briefly. Based on this, the fully automated process chain involving computer-aided design (CAD) model creation, FE mesh morphing, FE analysis, and postprocessing is executed. Here, the mesh morphing process is presented involving a discussion of the mesh quality. The process robustness is assessed and quantified referring to the impact on input parameter correlation. Finally, the result quantities of the probabilistic FE simulation are evaluated in terms of sensitivities. For this purpose, regions of interest are determined, wherein the statistical analysis is conducted to achieve the sensitivity ranking. A significant influence of the considered geometric uncertainties onto mechanical output quantities is observed, which motivates to incorporate these in modern design strategies or robust optimization.


2012 ◽  
Vol 538-541 ◽  
pp. 2681-2684
Author(s):  
Zhi Cheng Huang

Took a type of ceramics for daily use vertical type high pressure grouting machine as the object of study, study the stress and strain of its upper and lower mould plates. Established their 3D model by CAD software Pro-E, and then import them into finite element analysis software to analysis the value and distribution of the stress and strain. The analysis results can provide some reference for design, and have some engineering and practical value.


Author(s):  
Z Yi ◽  
WZ Fu ◽  
MZ Li

In order to obtain a higher pressure capacity for the high-pressure die with a larger sample cavity, two types of two-layer split dies with a round cylinder and a quadrate cylinder were designed based on the conventional belt-type die. Finite element analysis was performed to investigate the stress distributions and pressure capacities of the high-pressure dies using a derived Mohr–Coulomb criterion and the von Mises criterion for the cylinder and supporting rings, respectively. As predicted by the finite element analysis results, in the two-layer split dies with a round cylinder, the stress state of the cylinder can be only slightly improved; and the von Mises stress of the first layer supporting ring can be hardly decreased. However, in the two-layer split dies with a quadrate cylinder and sample cavity, the stress state of the cylinder can be remarkably improved. Simultaneously, the von Mises stress of the supporting rings, especially for the first-layer supporting ring, can be also effectively decreased. The pressure capacities of the two-layer split dies with a round cylinder and a quadrate cylinder are 16.5% and 63.9% higher with respect to the conventional belt-type die.


Author(s):  
Joshua Kimtai Ngoret ◽  
Venkata Parasuram Kommula

This paper presents results from modeling of Compressor Turbine (CT) blades for short-haul aircraft fleet occasioned by thermo-mechanical stresses in order to comprehend the occurrence of premature failure. A 3D PT6A-114A engine high pressure (HP) CT blade geometrical model was developed in commercial CAD-SolidWorks, then imported to ANSYS 15.0 environment for finite element analysis (FEA). The CT blade was investigated for transient thermal stresses from heat generated by the combustors and static structural stresses from rotational velocities of the engine which account for 80% of inertial field during flight. The results revealed that the blades could have served for another 1.44% of the time they were in service.


Author(s):  
Prenil Poulose ◽  
Zhong Hu

Strength evaluation and failure prediction on a modern composite wind turbine blade have been conducted using finite element analysis. A 3-dimensional finite element model has been developed. Stresses and deflections in the blade under extreme storm conditions have been investigated for different materials. The conventional wood design turbine blade has been compared with the advanced E-glass fiber and Carbon epoxy composite blades. Strength has been analyzed and compared for blades with different laminated layer stacking sequences and fiber orientations for a composite material. Safety design and failure prediction have been conducted based on the different failure criteria. The simulation error estimation has been evaluated. Simulation results have shown that finite element analysis is crucial for designing and optimizing composite wind turbine blades.


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