Adaptive Flow Field Thermal Modeling Techniques for Turbine Rotor-Stator Cavities

2013 ◽  
Author(s):  
Jose Maria Rey Villazón ◽  
Martin Berthold ◽  
Arnold Kühhorn
Keyword(s):  
Sensitivity Analysis ◽  
Flow Field ◽  
Boundary Conditions ◽  
Thermal Modeling ◽  
Turbine Rotor ◽  
Special Focus ◽  
Fe Model ◽  
Preliminary Design ◽  
Design Assessment ◽  
The Impact

At preliminary design stages of the turbine discs design process, reducing uncertainty in the thermal prediction of critical parts models is decisive to bid a competitive technology in the aerospace industry. This paper describes a novel approach to develop adaptive thermal modeling methods for non-gaspath turbine components. The proposed techniques allow automated scaling of disc cavities during preliminary design assessment of turbine architectures. The research undertaken in this work begins with an overview of the past investigations on the flow field in cavities of the air system surrounding the turbine discs. A theoretical approach is followed to identify the impact of the design geometry and operation parameters of a simplistic rotor-stator cavity, with special focus on swirl and windage effects. Then, a parametric CFD process is set up to conduct sensitivity analysis of the flow field properties. The CFD sensitivity analysis confirmed the parameter influences concluded from the theoretical study. The findings from the CFD automated studies are used to enhance the boundary conditions of a thermal FE-model of an actual high pressure turbine. The new set of thermal boundary conditions adapts the flow field to changes in the cavity parameters. It was found that the deviation to experimental data of the traditional preliminary modeling technique is about 4 times higher as the deviation of the CFD-enhanced technique. When running the FE-model through a transient cycle, the results from the CFD-enhanced method are significantly closer to the test data than those from the traditional method, which suggests there is high potential for using these adaptive thermal techniques during turbine preliminary design stages.

Automated Thermal and Stress Preliminary Analyses Applied to a Turbine Rotor

2016 ◽  
Author(s):  
Maxime Moret ◽  
Alexandre Delecourt ◽  
Hany Moustapha ◽  
Francois Garnier ◽  
Acher-Igal Abenhaim
Keyword(s):  
Design Process ◽  
Turbine Rotor ◽  
Tip Clearance ◽  
Conceptual System ◽  
Preliminary Design ◽  
Design Phase ◽  
Detailed Design ◽  
Turbine Engine ◽  
Cad Models ◽  
The Impact

The use of Multidisciplinary Design Optimization (MDO) techniques at the preliminary design phase (PMDO) of a gas turbine engine allows investing more effort at the pre-detailed phase in order to prevent the selection of an unsatisfactory concept early in the design process. Considering the impact of the turbine tip clearance on an engine’s efficiency, an accurate tool to predict the tip gap is a mandatory step towards the implementation of a full PMDO system for the turbine design. Tip clearance calculation is a good candidate for PMDO technique implementation considering that it implies various analyses conducted on both the rotor and stator. As a first step to the development of such tip clearance calculator satisfying PMDO principles, the present work explores the automation feasibility of the whole analysis phase of a turbine rotor preliminary design process and the potential increase in the accuracy of results and time gains. The proposed conceptual system integrates a thermal boundary conditions automated calculator and interacts with a simplified air system generator and with several conception tools based on parameterized CAD models. Great improvements were found when comparing this work’s analysis results with regular pre-detailed level tools, as they revealed to be close to the one generated by the detailed design tools used as target. Moreover, this design process revealed to be faster than a common preliminary design phase while leading to a reduction of time spent at the detailed design phase. By requiring fewer user inputs, this system decreases the risk of human errors while entirely leaving the important decisions to the designer.

The impact of boundary conditions in free flow field step electrophoresis

1989 ◽  
Vol 10 (10) ◽  
pp. 697-704 ◽  
Author(s):  
Ariane Heydt ◽  
Richard A. Mosher
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Free Flow ◽  
The Impact

Adaptive Preliminary-Design Workflow for Aero Engine Secondary Air System Cavities With an Application Case of Windage and Heat Transfer in a Rotor-Stator Cavity With Axial Through Flow

2018 ◽  
Author(s):  
Toni Wildow ◽  
Hubert Dengg ◽  
Klaus Höschler ◽  
Jonathan Sommerfeld
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Design Stage ◽  
Design Parameters ◽  
Preliminary Design ◽  
Geometry Model ◽  
Through Flow ◽  
Air System ◽  
Secondary Air ◽  
The Impact

At the preliminary design stage of the engine design process, the behaviour and efficiency of different engine designs are investigated and evaluated in order to find a best matching design for a set of engine objectives and requirements. The prediction of critical part temperatures as well as the reduction of the uncertainty of these predictions is decisive to bid a competitive technology in aerospace technology. Automated workflows and Design of Experiments (DOE) are widely used to investigate large number of designs and to find an optimized solution. Nowadays, technological progress in computational power as well as new strategies for data handling and management enables the implementation of large DOEs and multi-objective optimizations in less time, which also allows the consideration of more detailed investigations in early design stages. This paper describes an approach for a preliminary-design workflow that implements adaptive modelling and evaluation methods for cavities in the secondary air system (SAS). The starting point for the workflow is a parametric geometry model defining the rotating and static components. The flow network within the SAS is automatically recognized and CFD and Thermal-FE models are automatically generated using a library of generic models. Adaptive evaluation algorithms are developed and used to predict values for structural, air system and thermal behaviour. Furthermore, these models and evaluation techniques can be implemented in a DOE to investigate the impact of design parameters on the predicted values. The findings from the automated studies can be used to enhance the boundary conditions of actual design models in later design stages. A design investigation on a rotor-stator cavity with axial through flow has been undertaken using the proposed workflow to extract windage, flow field and heat transfer information from adiabatic CFD calculations for use in thermal modelling. A DOE has been set up to conduct a sensitivity analysis of the flow field properties and to identify the impact of the design parameters. Additionally, impacts on the distribution of the flow field parameters along the rotating surface are recognized, which offers a better prediction for local effects in the thermal FE model.

Analysis of Lumped Deterministic Source Terms and Their Sub-Components in a Stage 1 High Pressure Turbine Rotor

2008 ◽  
Author(s):  
Jon Ratzlaff ◽  
Paul D. Orkwis ◽  
Christopher Noll ◽  
Gary Steuber
Keyword(s):  
Flow Field ◽  
Time Series Data ◽  
Turbine Rotor ◽  
Series Data ◽  
Numerical Dissipation ◽  
Source Terms ◽  
Governing Equations ◽  
High Pressure Turbine ◽  
Stage 1 ◽  
The Impact

A GE proprietary code has been used to extract the Lumped Deterministic Source Terms (LDSTs) for the five governing equations: continuity, r, θ, z-momentum, and energy; as well as the two turbulence equations, from a converged unsteady time-averaged flow field. LDSTs are the opposite of the fluxes contained in the solution residuals for a time averaged flow field. They describe the cumulative effects of unsteadiness contained in the time-averaged solution. It has been shown that the addition of these terms to the steady residual operator in this code will drive the solution to the time averaged unsteady solution. The contributions of the LDST components, i.e. the residuals from the Euler, viscous and numerical dissipation, were studied to assess how they build the total LDST. Another approach to computing the inviscid source terms directly from time series data was also compared to the respective total and shows that the LDSTs are composed primarily of the inviscid component terms. In addition, attaining a time-averaged solution with a steady solver has been found to be sensitive to the boundary conditions. Results from one boundary condition set are presented in an error form to gauge the impact on the solution.

Setup, Validation and Probabilistic Robustness Estimation of a Model for Prediction of LCF in Steam Turbine Rotors

2016 ◽  
Author(s):  
David Pusch ◽  
Matthias Voigt ◽  
Konrad Vogeler ◽  
Peter Dumstorff ◽  
Henning Almstedt
Keyword(s):  
Boundary Conditions ◽  
Steam Turbine ◽  
Elastic Stress ◽  
Turbine Rotor ◽  
Sensitivity Study ◽  
Fe Model ◽  
Model Accuracy ◽  
Steam Turbine Rotor ◽  
Steam Parameters ◽  
Probabilistic Robustness

Flexibility and availability together with fast startup times become more and more important for steam turbine operation. Exact knowledge about the turbine components stresses and lifetime consumption during transient operation is a prerequisite in order to meet these requirements. A transient FE model of an intermediate pressure steam turbine rotor was generated, allowing the prediction of temperature and elastic stress field during turbine startup, load changes and shutdown. Operating data of the steam parameters and of a thermocouple inside the wall of the turbine inner casing were used to indirectly validate the thermal FE model in order to reproduce the measured metal temperatures in a proper accuracy. Subsequently a probabilistic sensitivity study was performed in order to identify the influence of scattering or not well known boundary conditions on the calculated lifetime consumption of the steam turbine rotor during a cold start. This in fact provides information about the accuracy of the prediction. The results of the sensitivity study also help to improve the model accuracy by identifying the boundary conditions with the largest impact on lifetime prediction uncertainty, i.e. the boundary conditions that need further investigation.

scholarly journals Stress field sensitivity analysis in a sedimentary sequence of the Alpine foreland, northern Switzerland

Solid Earth ◽  
2015 ◽  
Vol 6 (2) ◽  
pp. 533-552 ◽  
Author(s):  
T. Hergert ◽  
O. Heidbach ◽  
K. Reiter ◽  
S. B. Giger ◽  
P. Marschall
Keyword(s):  
Mechanical Properties ◽  
Sensitivity Analysis ◽  
Stress Field ◽  
Boundary Conditions ◽  
Plastic Material ◽  
Empirical Relationship ◽  
Relevant Parameter ◽  
Sedimentary Sequence ◽  
Alpine Foreland ◽  
The Impact

Abstract. The stress field at depth is a relevant parameter for the design of subsurface constructions and reservoir management. Yet the distortion of the regional stress field due to local-scale features such as sedimentary and tectonic structures or topography is often poorly constrained. We conduct a stress sensitivity analysis using 3-D numerical geomechanical modelling with an elasto-plastic material law to explore the impact of such site-specific features on the stress field in a sedimentary sequence of the Swiss Alpine foreland. The model's dimensions are 14 × 14 × 3 km3 and it contains 10 units with different mechanical properties, intersected by two regional fault zones. An initial stress state is established involving a semi-empirical relationship between the ratio of horizontal to vertical stress and the overconsolidation ratio of argillaceous sediments. The model results indicate that local topography can affect the stress field significantly to depths greater than the relief contrasts at the surface, especially in conjunction with horizontal tectonic loading. The complexity and frictional properties of faults are also relevant. The greatest variability of the stress field arises across the different sedimentary units. Stress magnitudes and stress anisotropy are much larger in stiffer formations such as massive limestones than in softer argillaceous formations. The stiffer formations essentially carry the load of the far-field forces and are therefore more sensitive to changes of the boundary conditions. This general characteristic of stress distribution in the stiff and soft formations is broadly maintained also with progressive loading towards the plastic limit. The stress field in argillaceous sediments within a stack of formations with strongly contrasting mechanical properties like in the Alpine foreland appears to be relatively insensitive to changes in the tectonic boundary conditions and is largely controlled by the maximum stiffness contrast with respect to the load-bearing formations.

scholarly journals Stress field sensitivity analysis in a sedimentary sequence of the Alpine foreland, Northern Switzerland

2015 ◽  
Vol 7 (1) ◽  
pp. 711-756 ◽  
Author(s):  
T. Hergert ◽  
O. Heidbach ◽  
K. Reiter ◽  
S. B. Giger ◽  
P. Marschall
Keyword(s):  
Mechanical Properties ◽  
Sensitivity Analysis ◽  
Stress Field ◽  
Boundary Conditions ◽  
Plastic Material ◽  
Empirical Relationship ◽  
Relevant Parameter ◽  
Sedimentary Sequence ◽  
Alpine Foreland ◽  
The Impact

Abstract. The stress field at depth is a relevant parameter for the design of subsurface constructions and reservoir management. Yet the distortion of the regional stress field due to local-scale features such as sedimentary and tectonic structures or topography is often poorly constrained. We conduct a stress sensitivity analysis using 3-D numerical geomechanical modelling with an elasto-plastic material law to explore the impact of such site specific features on the stress field in a sedimentary sequence of the Swiss Alpine foreland. The model's dimensions are 14 km × 14 km × 3 km and it contains ten units with different mechanical properties, intersected by two regional fault zones. An initial stress state is established involving a semi-empirical relationship between the ratio of horizontal to vertical stress and the overconsolidation ratio of argillaceous sediments. The model results indicate that local topography can affect the stress field significantly to depths greater than the relief contrasts at the surface, especially in conjunction with horizontal tectonic loading. The complexity and frictional properties of faults are also relevant. The greatest variability of the stress field arises across the different sedimentary units. Stress magnitudes and stress anisotropy are much larger in stiffer formations such as massive limestones than in softer argillaceous formations. The stiffer formations essentially carry the load of the far-field forces and are therefore more sensitive to changes of the boundary conditions. This general characteristic of stress distribution in the stiff and soft formations is broadly maintained also with progressive loading towards the plastic limit. The stress field in argillaceous sediments within a stack of formations with strongly contrasting mechanical properties like in the Alpine foreland appears to be relatively insensitive to changes in the tectonic boundary conditions and is largely controlled by the maximum stiffness contrast with respect to the load-bearing formations.

Chemical Transport Facilitated by Multiphase Flow Systems1

1985 ◽  
Vol 17 (9) ◽  
pp. 1-12 ◽  
Author(s):  
Carl G. Enfield
Keyword(s):  
Organic Carbon ◽  
Boundary Conditions ◽  
Transport Equation ◽  
Fluid Phase ◽  
Chemical Transport ◽  
Facilitated Transport ◽  
Organic Fraction ◽  
Dispersive Transport ◽  
Transformation Of Variables ◽  
The Impact

Relatively immobile chemicals have been observed moving significantly faster than anticipated from hydrophobic theory. A theory is developed considering transport in three mobile fluid phases which can be used to describe this facilitated transport. The convective dispersive transport equation is solved utilizing a transformation of variables which permits utilizing existing solutions covering a wide variety of boundary conditions. The impact of the facilitated transport is demonstrated for one case where the soils organic carbon is 10%. If 2% of the fluid phase is an organic fraction, the theory developed projects that hydrophobic theory may underestimate mobility by more than 100 times. At concentrations of dissolved organic carbon normally observed in nature (5 - 10 mg/l), a measurable increased mobility is anticipated for the very immobile compounds like dioxins.

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