Probabilistic FE-Analysis of Cooled High Pressure Turbine Blades: Part B — Probabilistic Analysis

2019 ◽  
Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger
Keyword(s):  
High Pressure ◽  
Cooling System ◽  
Probabilistic Method ◽  
Turbine Blades ◽  
Fe Analysis ◽  
Parametric Models ◽  
Fe Model ◽  
High Pressure Turbine ◽  
Mesh Morphing ◽  
The Impact

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.

Probabilistic Finite Element Analysis of Cooled High-Pressure Turbine Blades—Part B: Probabilistic Analysis

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Cooling System ◽  
Probabilistic Method ◽  
Fe Analysis ◽  
Parametric Models ◽  
Fe Model ◽  
High Pressure Turbine ◽  
Mesh Morphing ◽  
The Impact

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.

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

2019 ◽  
Author(s):  
Lars Högner ◽  
Matthias Voigt ◽  
Ronald Mailach ◽  
Marcus Meyer ◽  
Ulf Gerstberger
Keyword(s):  
High Pressure ◽  
Optical Measurement ◽  
Cooling System ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Fe Analysis ◽  
Parametric Models ◽  
High Pressure Turbine ◽  
Element Analysis ◽  
Cooling Passage

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.

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
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
High Pressure ◽  
Cooling System ◽  
Measurement Techniques ◽  
Turbine Blades ◽  
Parametric Models ◽  
High Pressure Turbine ◽  
Element Analysis ◽  
Cooling Passage

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.

Pulsating Cooling System for High Pressure Turbine Blades

2010 ◽  
Author(s):  
Marcos González ◽  
Guillermo Paniagua ◽  
Bayindir Saracoglu ◽  
Andrés Tiseira
Keyword(s):  
High Pressure ◽  
Cooling System ◽  
Turbine Blades ◽  
High Pressure Turbine

Gradient-Based Adjoint and Design of Experiment CFD Methodologies to Improve the Manufacturability of High Pressure Turbine Blades

2016 ◽  
Author(s):  
Giulio Zamboni ◽  
Gabriel Banks ◽  
Simon Bather
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Turbine Blades ◽  
Aerodynamic Performance ◽  
Correlation Factor ◽  
Control Points ◽  
High Pressure Turbine ◽  
Flow Capacity ◽  
Profile Tolerance ◽  
The Impact

The tolerance of a turbine blade aerofoil is determined by the requirements to achieve an aerodynamic performance in operation. In fact, the manufacturing tolerance applied to the profile is driven by the effects of geometrical non-conformances on the efficiency and flow capacity of the aerofoil. However, this tolerance also has an impact on the ease with which the aerofoil can be manufactured, with tighter tolerance leading to lower manufacturing conformity. This paper details the application of an adjoint RANS solver and the according series of Design of Experiments (DoE) CFD calculations for a high pressure turbine blade to the above problem. There are two aims of this work; the first is to show that simpler linear CFD perturbation can be used to evaluate the effect of the geometric non-conformance. The second is to validate the spatial geometric correlation factor of the control points used in the manufacturing process on the performance evaluation with DoE techniques. This also verified the applicability of the adjoint CFD techniques; in fact the adjoint CFD calculation is an order of magnitude less computationally expensive than a large series of DoE RANS CFD calculations. The results confirm that the peak suction area is the most critical control region for the effect on the efficiency and flow capacity. Moreover, the CFD investigations show that a significant level of correlation exists between the influence factors at different control points. This suggests that not only the amount of geometric deviation but also the stream surface variation of profile tolerance significantly influence the final aerodynamic performance. The results from this calculation allow the creation of a 3D sensitivity map which will be used during the manufacturing of the aerofoil to optimise the control of the spatial distribution of the geometric non-conformance and to directly assess the expected performance effect during the manufacturing quality inspection. The methodology detailed in this paper shows how the CFD adjoint methods could be used for improved manufacturability of turbine blades ensuring that the critical characteristic features are controlled on the surface, relaxing the profile tolerance on those surface areas where the impact on the aerodynamic performance is predicted to be lower.

Thermodynamic Aspects of Designing the New Siemens High Pressure Steam Turbine With Overload Valve for Supercritical Applications

2006 ◽  
Author(s):  
Frank Deidewig ◽  
Michael Wechsung
Keyword(s):  
High Pressure ◽  
Mass Flow ◽  
Cooling System ◽  
Point Of View ◽  
Internal Cooling ◽  
High Pressure Turbine ◽  
Axial Thrust ◽  
High Efficient ◽  
Main Steam ◽  
The Impact

Huge coal fueled power plants in the 1000MWel class are requiring high efficient steam turbines which can handle supercritical steam conditions up to 300bar and 600°C. Besides these boundary conditions, the capability for stabilising the grid fluctuations is also one key requirement. Siemens is focussing on this topic by using the so-called overload valve(s), which enhance the maximum amount of main steam mass flow entering the high-pressure turbine by use of additional valve(s). Using this technique, a power increase in the range of up to 20% is theoretically achievable. Siemens PG has collected a lot of positive service experiences throughout the past decades with this technique, and therefore this principle is being well established in the field. The connection between the additional steam mass flow passing through the overload valve and the standard blading path is somewhat downstream from the first stage. These connecting points can be varied (for this current turbine design) — if necessary — between the third and fifth stage after the turbine inlet. From an economic point of view, the approach of extending the power range via overload valves is even better than throttling the whole machine during standard operating condition and opening the valves fully at certain peak load requirements. Historically based, Siemens designs and manufactures reaction stages, ‘reaction turbines’, which must be thrust compensated via a separate piston to equalize and reduce the overall axial thrust down to a small number. Increasing the main steam temperatures up to the previously mentioned levels makes the internal cooling device of this thrust equilibrium piston a major key point for the whole turbine. No external cooling pipe-work or special materials are required. In Figure 1, a longitudinal cross-section 3D-view of the newly designed high-pressure turbine is drawn. The outer casing — at the steam inlet regime — is cast steel of 10% chromium content with significantly reduced wall thickness, whereas the outer casing at the hp-exhaust is a 1% chromium steel. The thrust-balancing piston on the shaft can be identified on the right hand side near the steam inlet channel. As noted further on, the steam outlet channels are both connected to the lower part of the turbine, whereas the inlet chambers are located at 3 o’clock and 9 o’clock, respectively. The outer casing has no horizontal splitting line; the turbine is being built as a barrel-design. This paper deals with the described turbine regarding the major design criteria from the thermodynamic point of view. Based on several calculations, the following design topics were covered: • Developing a turbine-internal cooling system for the thrust equilibrium/balancing piston as well as for the inner and outer casing. • Evaluation of staged piston with new internal cooling system adjusted for the impact on heat rate. • Quantification of all related mass flows, temperatures and pressures. • Axial thrust calculation to determine the required diameters of the staged piston. • General remarks concerning efficiency behaviour of hp-turbines with different geometrical designs.

Investigation Into Coupling Techniques for a High Pressure Turbine Blade Tip

2015 ◽  
Author(s):  
Stefano Caloni ◽  
Shahrokh Shahpar
Keyword(s):  
High Pressure ◽  
Temperature Distribution ◽  
Cooling System ◽  
Convective Zone ◽  
Fe Model ◽  
Internal Cooling ◽  
Cfd Model ◽  
Coupled Simulation ◽  
High Pressure Turbine ◽  
First Case

In this paper the aero-thermal performance of a high pressure turbine rotor blade is investigated, making use of coupled and uncoupled simulations. The fluid domain is solved via Finite Volume analyses whilst Finite Elements are used in the solid domain. In the CFD model, a temperature distribution is imposed as a boundary condition at the interfaces between the fluid and the solid domain. In the corresponding FE model, a convective zone is applied. The parameters of the convective zone are computed from the CFD analysis. In the uncoupled simulations, the convective zone can make use of a two or three parameters model. In the first case, a linear relation between the heat flux and the wall temperature is assumed, whilst in the second model a parabolic relation is adopted. In the coupled simulation, an iterative process is used where the temperature distribution in the CFD model and the parameters of the convective zone in the FE model are updated at every iteration. The aforementioned three models are applied to a shroudless blade with and without an internal cooling system. When the blade is uncooled, all three methods offer a close prediction of the temperature reached by the component. However, when the blade is internally cooled the convective zone based on two parameters fails to provide a trustworthy prediction. The three-parameter convective zone, on the other hand, shows a closer agreement with the coupled simulation. The couple simulation is then applied to investigate the performance of three different tip configurations, a simple cavity, a novel contoured cavity and a tip with a small winglet. The small winglet shows a significant improvement in aerodynamic performance as well as a reduction in the operative temperature.

Experimental Investigation of Two Competitive High Pressure Turbine Blade Cooling Systems

2017 ◽  
Author(s):  
Sergiy Risnyk ◽  
Andriy Artushenko ◽  
Igor Kravchenko ◽  
Sergii Borys
Keyword(s):  
High Pressure ◽  
Turbine Blade ◽  
Film Cooling ◽  
Cooling System ◽  
Turbine Blades ◽  
Turbine Rotor ◽  
High Pressure Turbine ◽  
Cooling Systems ◽  
Turbine Blade Cooling ◽  
Blade Cooling

Aeroengine high-pressure turbine (HPT) is the key engine component. HPT blade must withstand high inlet temperatures and mechanical loads providing the necessary level of the efficiency. To achieve these objectives effective and complex blade cooling systems (internal convective and film cooling) are used in the HPT design. The objective of this project is to design and investigate the aeroengine HPT blade cooling system that is able to withstand the blade inlet gas temperature level of approx. 1900K but with the minimal cooling airflow amount. HPT blade of the aeroengine with unducted fan (UDF) was taken as a baseline design, namely, the monocrystal blade with a convective multipass system and the film cooling. Advanced HPT blade inter-wall cooling system was designed, investigated and compared with the typical baseline HPT blade. In the advanced HPT blade inter-wall cooling system special types and structure of cooling channels are used. Both types of cooling systems were investigated experimentally in the turbine rotor of the high temperature core engine. Measurements of turbine blades temperatures were performed using crystal temperature sensors (CTS). HPT blades with two competitive cooling systems incorporated with CTS (0,2–0,3 mm size) were installed in the turbine rotor of the core engine and tested on the engine Maximal rate. After tests and the engine disassembly CTSs were extracted and the characteristics of the CTS crystal lattice were transcribed in temperature values. Thermal state of both two competitive cooling systems was validated by experimental data. Numerical and experimental results obtained in the research of HPT blade cooling system are presented in the article. Aeroengine high pressure turbine blade cooling systems designs are described.

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