Probabilistic Fracture Mechanics for Heavy Duty Gas Turbine Rotor Forgings

2017 ◽  
Author(s):  
Kai Kadau ◽  
Phillip W. Gravett ◽  
Christian Amann
Keyword(s):  
Fracture Mechanics ◽  
High Performance ◽  
Computing Methodology ◽  
Direct Simulation Monte Carlo ◽  
Turbine Rotor ◽  
Heavy Duty ◽  
Element Analysis ◽  
Probabilistic Fracture Mechanics ◽  
Risk Of Failure ◽  
Heavy Duty Gas Turbine

We developed and successfully applied a direct simulation Monte-Carlo scheme to quantify the risk of fracture for heavy duty rotors commonly used in the energy sector. The developed Probabilistic Fracture Mechanics high-performance computing methodology and code ProbFM routinely assesses relevant modes of operation for a component by performing billions of individual fracture mechanics simulations. The methodology can be used for new design and life-optimization of components, as well as for the risk of failure quantification of in service rotors and their re-qualifications in conjunction with non-destructive examination techniques, such as ultrasonic testing. The developed probabilistic scheme integrates material data, ultra-sonic testing information, duty-cycle data, and finite element analysis in order to determine the risk of failure. The methodology provides an integrative and robust measure of the fitness for service and allows for a save and reliable operation management of heavy duty rotating equipment.

Probabilistic Fracture Mechanics for Heavy-Duty Gas Turbine Rotor Forgings

2018 ◽  
Vol 140 (6) ◽  
Author(s):  
Kai Kadau ◽  
Phillip W. Gravett ◽  
Christian Amann
Keyword(s):  
Fracture Mechanics ◽  
High Performance ◽  
Computing Methodology ◽  
Direct Simulation Monte Carlo ◽  
Turbine Rotor ◽  
Heavy Duty ◽  
Element Analysis ◽  
Nondestructive Examination ◽  
Probabilistic Fracture Mechanics ◽  
Heavy Duty Gas Turbine

We developed and successfully applied a direct simulation Monte Carlo (MC) scheme to quantify the risk of fracture for heavy-duty rotors commonly used in the energy sector. The developed probabilistic fracture mechanics (FM), high-performance computing methodology, and code ProbFM routinely assess relevant modes of operation for a component by performing billions of individual FM simulations. The methodology can be used for new design and life optimization of components, as well as for the risk of failure RoF quantification of in service rotors and their requalifications in conjunction with nondestructive examination techniques, such as ultrasonic testing (UT). The developed probabilistic scheme integrates material data, UT information, duty-cycle data, and finite element analysis (FEA) in order to determine the RoF. The methodology provides an integrative and robust measure of the fitness for service and allows for a save and reliable operation management of heavy-duty rotating equipment.

Application of Advanced Probabilistic Fracture Mechanics to Life Evaluation of Turbine Rotor Blade Attachments

1995 ◽  
Author(s):  
H. R. Millwater ◽  
Y.-T. Wu ◽  
J. W. Cardinal ◽  
G. G. Chell
Keyword(s):  
Fracture Mechanics ◽  
Computational Algorithm ◽  
Operating Time ◽  
Turbine Rotor ◽  
Life Assessment ◽  
Inspection Planning ◽  
Element Analysis ◽  
Turbine Rotor Blade ◽  
Probabilistic Fracture Mechanics ◽  
Life Evaluation

This paper describes the application of an advanced probabilistic fracture mechanics computational algorithm with inspection simulation to the probabilistic life assessment of a turbine blade attachment, sometimes referred to as a steeple or fir tree. The life of the steeple is limited by high cycle fatigue. The methodology utilized combines structural finite element analysis, stochastic fatigue crack growth, and crack inspection and repair. The resulting information provides the engineer with an assessment of the probability of failure of the structure as a function of operating time and the effect of the inspection procedure. This information can form the basis of inspection planning and retirement-for-cause decisions.

A new computational method for predicting the thermal bow of a rotor

2018 ◽  
Vol 233 (12) ◽  
pp. 4372-4380 ◽  
Author(s):  
M Zhuo ◽  
LH Yang ◽  
K Xia ◽  
L Yu
Keyword(s):  
Analytical Solution ◽  
Gas Turbine ◽  
Turbine Rotor ◽  
Computational Method ◽  
Practical Significance ◽  
Complex Structures ◽  
Heavy Duty ◽  
Element Analysis ◽  
First Order ◽  
Heavy Duty Gas Turbine

In a heavy-duty gas turbine, when hot rotor is left cooled in standstill condition, thermal bow occurs due to natural convection, which may result in high vibrations in a subsequent restart. Usually, a turning gear is immediately started after shutdown of gas turbine to slowly roll and uniformly cool the rotor in order to prevent thermal bow, which is called turning gear operation. The minimum turning time and the acceptable temperature of wheel space are two important indexes of turning gear operation, and their determination highly depends on accurate prediction of thermal bow. This paper proposes an analytical method to predict the thermal bow behavior of rotors with complex structures and investigates the effect of turning time on thermal bow. First, the general form of analytical solution of rotor thermal bow is derived and validated through both finite element analysis and experiments. Then the analytical solution is applied in a heavy-duty gas turbine to predict the most severe thermal bow behavior of the rotor with no turning gear in operation before standstill. Finally, the effect of turning time on thermal bow is investigated, and the indexes to achieve acceptable thermal bow are discussed. Results show that the shape of thermal bow of the gas turbine rotor is close to the first-order mode shape; the peak of the most severe thermal bow reaches 0.7 mm after 3.8 h of cooling and the decrease of thermal bow is much slower than the increase. Besides, the maximum thermal bow of the rotor due to insufficient turning gear operation presents an exponential decay with turning time and lies in linear relationship with the temperature of the same location. These two relationships help determine the minimum turning time and acceptable temperature of wheel space to attain an acceptable bow and thus have practical significance to develop and optimize turning gear operations.

High-Performance Computing Probabilistic Fracture Mechanics Implementation for Gas Turbine Rotor Disks on Distributed Architectures Including Graphics Processing Units (GPUs)

2021 ◽  
Author(s):  
Mrugesh Gajjar ◽  
Christian Amann ◽  
Kai Kadau
Keyword(s):  
Monte Carlo ◽  
Fracture Mechanics ◽  
Gas Turbine ◽  
Graphics Processing Units ◽  
High Performance ◽  
Message Passing Interface ◽  
Turbine Rotor ◽  
Integration Step ◽  
Probabilistic Fracture Mechanics ◽  
Runge Kutta

Abstract We present an efficient Monte Carlo based probabilistic fracture mechanics simulation implementation for heterogeneous high-performance (HPC) architectures including CPUs and GPUs. The specific application focuses on large heavy-duty gas turbine rotor components for the energy sector. A reliable probabilistic risk quantification requires the simulation of millions to billions of Monte Carlo (MC) samples. We apply a modified Runge-Kutta algorithm in order to solve numerically the fatigue crack growth for this large number of cracks for varying initial crack sizes, locations, material and service conditions. This compute intensive simulation has already been demonstrated to perform efficiently and scalable on parallel and distributed HPC architectures including hundreds of CPUs utilizing the Message Passing Interface (MPI) paradigm. In this work, we go a step further and include GPUs in our parallelization strategy. We develop a load distribution scheme to share one or more GPUs on compute nodes distributed over a network. We detail technical challenges and solution strategies in performing the simulations on GPUs efficiently. We show that the key computation of the modified Runge-Kutta integration step speeds up over two orders of magnitude on a typical GPU compared to a single threaded CPU. This is supported by our use of GPU textures for efficient interpolation of multi-dimensional tables utilized in the implementation. We demonstrate weak and strong scaling of our GPU implementation, i.e., that we can efficiently utilize a large number of GPUs/CPUs in order to solve for more MC samples, or reduce the computational turn-around time, respectively. On seven different GPUs spanning four generations, the presented probabilistic fracture mechanics simulation tool ProbFM achieves a speed-up ranging from 16.4x to 47.4x compared to single threaded CPU implementation.

High-Performance Computing Probabilistic Fracture Mechanics Implementation for Gas Turbine Rotor Disks On Distributed Architectures Including Graphics Processing Units (GPUS)

2021 ◽  
Author(s):  
Mrugesh Gajjar ◽  
Christian Amann ◽  
Kai Kadau
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbine ◽  
Graphics Processing Units ◽  
High Performance ◽  
Message Passing Interface ◽  
Turbine Rotor ◽  
Integration Step ◽  
Distributed Architectures ◽  
Probabilistic Fracture Mechanics ◽  
Runge Kutta

Abstract We present an efficient Monte Carlo (MC) based probabilistic fracture mechanics simulation implementation on heterogeneous high-performance (HPC) architectures including CPUs and GPUs for large heavy-duty gas turbine rotor components for the energy sector. A reliable probabilistic risk quantification requires simulating millions to billions of MC samples. We apply a modified Runge-Kutta algorithm to solve numerically the fatigue crack growth for this large number of cracks for varying initial crack sizes, locations, material and service conditions. This compute intensive simulation was demonstrated to perform efficiently and scalable on parallel and distributed architectures with hundreds of CPUs utilizing Message Passing Interface (MPI). In this work, we include GPUs in parallelization strategy. We develop a load distribution scheme to share one or more GPUs on compute nodes distributed over network. We detail technical challenges and strategies in performing the simulations on GPUs efficiently. We show that the key computation of the modified Runge-Kutta integration step speeds up over two orders of magnitude on a typical GPU compared to a single threaded CPU supported by use of GPU textures for efficient interpolation of multi-dimensional tables. We demonstrate weak and strong scaling of our GPU implementation, i.e., that we can efficiently utilize large number of GPUs/CPUs to solve for more MC samples, or reduce the computational turnaround time, respectively. On seven different GPUs spanning four generations, our probabilistic fracture mechanics simulation tool ProbFM achieves speedups ranging from 16.4x to 47.4x compared to single threaded CPU implementation.

On the Transferability of Probabilistic Fracture Mechanics Results for Scaled 50Hz and 60Hz Heavy Duty Gas Turbine Rotor Disks

2018 ◽  
Author(s):  
Christian Amann ◽  
Kai Kadau ◽  
Peter Gumbsch
Keyword(s):  
Fracture Mechanics ◽  
Gas Turbines ◽  
Volume Ratio ◽  
Transient Behavior ◽  
Turbine Rotor ◽  
The Other ◽  
Heavy Duty ◽  
Design Work ◽  
Probabilistic Fracture Mechanics ◽  
Rotor Design

In the development of heavy duty gas turbines for the energy sector oftentimes the majority of the design work is performed in either the 50 Hz or the 60 Hz size. Many aspects of the designed engine for one market (50 Hz as an example) can then be used to design with significantly reduced effort for the other market (i.e. 60 Hz). For example, most dimensions of rotor components can be geometrically scaled such that centrifugal forces in those massively rotating parts are conserved. This article investigates the transferability of probabilistic fracture mechanics results from one market to the other one. Or in other words: can we perform probabilistic fracture mechanics for the 50 Hz rotor design and deduce the risk of failure for the scaled 60 Hz design (or vice versa)? Multiple challenges must be considered in the transferability including the different volume, surface to volume ratio, as well as the different transient behavior for the smaller 60 Hz design. We address that challenge by building up complexity for a generic rotor design in order to separate the different effects and associated design features. We then discuss several Siemens rotor designs with respect to transferability of probabilistic fracture mechanics results and correlations to deterministic approaches. This work enables the creation of design rules to avoid unnecessary work for scaled 50 Hz/60 Hz market engines and therefore supports the reduction of product development costs.

Application of Advanced Probabilistic Fracture Mechanics to Life Evaluation of Turbine Rotor Blade Attachments

1996 ◽  
Vol 118 (2) ◽  
pp. 394-398 ◽  
Author(s):  
H. R. Millwater ◽  
Y.-T. Wu ◽  
J. W. Cardinal ◽  
G. G. Chell
Keyword(s):  
Fracture Mechanics ◽  
Computational Algorithm ◽  
Operating Time ◽  
Turbine Rotor ◽  
Life Assessment ◽  
Inspection Planning ◽  
Element Analysis ◽  
Turbine Rotor Blade ◽  
Probabilistic Fracture Mechanics ◽  
Life Evaluation

This paper describes the application of an advanced probabilistic fracture mechanics computational algorithm with inspection simulation to the probabilistic life assessment of a turbine blade attachment, sometimes referred to as a steeple or fir tree. The life of the steeple is limited by high cycle fatigue. The methodology utilized combines structural finite element analysis, stochastic fatigue crack growth, and crack inspection and repair. The resulting information provides the engineer with an assessment of the probability of failure of the structure as a function of operating time and the effect of the inspection procedure. This information can form the basis of inspection planning and retirement-for-cause decisions.

Experience With Large Heavy-Duty Gas Turbine Rotors

1981 ◽  
Author(s):  
O. R. Schmoch ◽  
B. Deblon
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Strength Properties ◽  
Operating Conditions ◽  
Material Strength ◽  
Heavy Duty ◽  
Turbine Rotors ◽  
Heavy Duty Gas Turbine ◽  
Response To Temperature

The peripheral speeds of the rotors of large heavy-duty gas turbines have reached levels which place extremely high demands on material strength properties. The particular requirements of gas turbine rotors, as a result of the cycle, operating conditions and the ensuing overall concepts, have led different gas turbine manufacturers to produce special structural designs to resolve these problems. In this connection, a report is given here on a gas turbine rotor consisting of separate discs which are held together by a center bolt and mutually centered by radial serrations in a manner permitting expansion and contraction in response to temperature changges. In particular, the experience gained in the manufacture, operation and servicing are discussed.

Parametric Study on Pressure-Temperature Limit Curve

2016 ◽  
Author(s):  
Shin-Beom Choi ◽  
Han-Bum Surh ◽  
Jong-Wook Kim
Keyword(s):  
Sensitivity Analysis ◽  
Fracture Mechanics ◽  
Crack Depth ◽  
Temperature Limit ◽  
Round Robin ◽  
Robin Problem ◽  
Limit Curve ◽  
Element Analysis ◽  
Probabilistic Fracture Mechanics ◽  
Key Parameter

The final goal of this study is to solve the round-robin problem for the safety of a reactor pressure vessel by adopting a finite element analysis and probabilistic fracture mechanics. To do so, a sensitivity analysis and a deterministic analysis should be conducted. This paper contains the results of the sensitivity analysis as intermediate results of a round-robin problem. Key parameters such as the initial Reference Temperature for Nil Ductility Transition, Ni contents, Cu contents, fluence, and input transient were chosen to conduct the sensitivity analysis. In addition, different values of crack depth to the thickness ratio are considered to develop FE models. Moreover, a series of FE analyses are carried out. As a result, each key parameter has an influence on RTNDT and KIc. This means that the P-T limit curve is shifted. If the value of each key parameter is increased, the P-T limit curve is moved to the right side. Therefore, the operating area of the P-T limit curve should be reduced. The results of this paper will be very helpful in enhancing our understanding of the P-T limit curve. In addition, it will be used to adjust the probabilistic fracture mechanics and solve the round-robin problem.

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