Simulation of Large and Complex Structures With Multiple Contacts and Wear

1992 ◽  
Author(s):  
B. S. Bagepalli ◽  
S. Dinc ◽  
B. Jlidi ◽  
I. Imam ◽  
J. Barnes ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Analytical Models ◽  
Contact Friction ◽  
Complex Structures ◽  
Accelerometer Data ◽  
Mechanism Analysis ◽  
Evaluation Tool ◽  
Simulation Code ◽  
Multiple Contacts ◽  
Field Samples

Abstract This paper deals with the simulation methodology of large and complex structures with multiple contacts and wear. The methodology developed is used to evaluate the dynamics and wear of gas turbine combustors. A unified approach of representing multiple rigid/elastic bodies with numerous contacts is developed. Representation is made, too, of the changing nature of these contacts — both geometric and material. The entire methodology is implemented in a generic and easy-to-use simulation code which serves as a useful generic design/analysis evaluation tool MAP (Mechanism Analysis Program). Appropriate analytical models for inter-material constitutive laws — both incremental (contact friction, pressure, damping, etc.) and cumulative (wear theories) — are incorporated in the tool. As applications of this approach, dynamic simulations of two different gas turbine combustor designs are run, and comparisons are made with real systems. Excellent correlations have been obtained, both with respect to laboratory test (accelerometer) data, and wear patterns at various contacts and junctions on field samples.

GATE: A Simulation Code for Analysis of Gas-Turbine Power Plants

1989 ◽  
Author(s):  
M. R. Erbes ◽  
R. R. Gay ◽  
A. Cohn
Keyword(s):  
Heat Transfer ◽  
User Interface ◽  
Power Plant ◽  
Gas Turbine ◽  
Graphical User Interface ◽  
Power Plants ◽  
Analytical Models ◽  
Simulation Studies ◽  
Simulation Code ◽  
Complex Design

The GATE (GAs Turbine Evaluation) code has been developed to evaluate the design and off-design performance of existing and advanced gas-turbine-based systems for power plant applications. By combining an intuitive, graphical user interface with detailed analytical models for the thermodynamic, heat-transfer and fluid-mechanical processes within gas-turbine-based power plants, GATE can be used by novices as well as experts for complex design and simulation studies. It can model a variety of gas turbine configurations and cooling technologies, and users can also interactively design and analyze an associated steam bottoming cycle. The basic formulations used in GATE are presented here, along with sample cases demonstrating the power and flexibility of the code.

scholarly journals Children’s moderate-to-vigorous physical activity on weekdays versus weekend days: a multi-country analysis

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Keith Brazendale ◽  
◽  
Michael W. Beets ◽  
Bridget Armstrong ◽  
R. Glenn Weaver ◽  
...  
Keyword(s):  
Physical Activity ◽  
Weight Status ◽  
Vigorous Physical Activity ◽  
Normal Weight ◽  
Analytical Models ◽  
Accelerometer Data ◽  
Inclusion Criteria ◽  
Total Wear ◽  
Valid Data ◽  
Country Analysis

Abstract Purpose The Structured Days Hypothesis (SDH) posits that children’s behaviors associated with obesity – such as physical activity – are more favorable on days that contain more ‘structure’ (i.e., a pre-planned, segmented, and adult-supervised environment) such as school weekdays, compared to days with less structure, such as weekend days. The purpose of this study was to compare children’s moderate-to-vigorous physical activity (MVPA) levels on weekdays versus weekend days using a large, multi-country, accelerometer-measured physical activity dataset. Methods Data were received from the International Children’s Accelerometer Database (ICAD) July 2019. The ICAD inclusion criteria for a valid day of wear, only non-intervention data (e.g., baseline intervention data), children with at least 1 weekday and 1 weekend day, and ICAD studies with data collected exclusively during school months, were included for analyses. Mixed effects models accounting for the nested nature of the data (i.e., days within children) assessed MVPA minutes per day (min/day MVPA) differences between weekdays and weekend days by region/country, adjusted for age, sex, and total wear time. Separate meta-analytical models explored differences by age and country/region for sex and child weight-status. Results/findings Valid data from 15 studies representing 5794 children (61% female, 10.7 ± 2.1 yrs., 24% with overweight/obesity) and 35,263 days of valid accelerometer data from 5 distinct countries/regions were used. Boys and girls accumulated 12.6 min/day (95% CI: 9.0, 16.2) and 9.4 min/day (95% CI: 7.2, 11.6) more MVPA on weekdays versus weekend days, respectively. Children from mainland Europe had the largest differences (17.1 min/day more MVPA on weekdays versus weekend days, 95% CI: 15.3, 19.0) compared to the other countries/regions. Children who were classified as overweight/obese or normal weight/underweight accumulated 9.5 min/day (95% CI: 6.9, 12.2) and 10.9 min/day (95% CI: 8.3, 13.5) of additional MVPA on weekdays versus weekend days, respectively. Conclusions Children from multiple countries/regions accumulated significantly more MVPA on weekdays versus weekend days during school months. This finding aligns with the SDH and warrants future intervention studies to prioritize less-structured days, such as weekend days, and to consider providing opportunities for all children to access additional opportunities to be active.

scholarly journals Metamodels of a gas turbine powered marine propulsion system for simulation and diagnostic purposes

2015 ◽  
Vol 12 (1) ◽  
pp. 1-14 ◽  
Author(s):  
U. Campora ◽  
M. Capelli ◽  
C. Cravero ◽  
R. Zaccone
Keyword(s):  
Gas Turbine ◽  
Response Surfaces ◽  
Propulsion System ◽  
Direct Simulation ◽  
Analysis Method ◽  
Simulation Code ◽  
Marine Propulsion ◽  
Performance Reduction ◽  
Input Variables ◽  
Marine Propulsion System

The paper presents the application of artificial neural network for simulation and diagnostic purposes applied to a gas turbine powered marine propulsion plant. A simulation code for the propulsion system, developed by the authors, has been extended to take into account components degradation or malfunctioning with the addition of performance reduction coefficients. The above coefficients become input variables to the analysis method and define the system status at a given operating point. The simulator is used to generate databases needed to perform a variable selection analysis and to tune response surfaces for both direct (simulation) and inverse (diagnostic) purposes. The application of the methodology to the propulsion system of an existing frigate version demonstrate the potential of the approach.

scholarly journals Minimal Structural ART Neural Network and Fault Diagnosis Application of Gas Turbine

2016 ◽  
Vol 10 (1) ◽  
pp. 13-22
Author(s):  
Qingyang Xu
Keyword(s):  
Neural Network ◽  
Fault Diagnosis ◽  
Gas Turbine ◽  
Cognitive Process ◽  
Simple Structure ◽  
High Efficiency ◽  
Complex Structures ◽  
Resonance Theory ◽  
Adaptive Resonance ◽  
Binary Input

Adaptive Resonance Theory (ART) model is a special neural network based on unsupervised learning which simulates the cognitive process of human. However, ART1 can be only used for binary input, and ART2 can be used for binary and analog vectors which have complex structures and complicated calculations. In order to improve the real-time performance of the network, a minimal structural ART is proposed which combines the merits of the two models by subsuming the bottom-up and top-down weight. The vector similarity test is used instead of vigilance test. Therefore, this algorithm has a simple structure like ART1 and good performance as ART2 which can be used for both binary and analog vector classification, and it has a high efficiency. Finally, a gas turbine fault diagnosis experiment exhibits the validity of the new network.

scholarly journals Impact of compressed air energy storage demands on gas turbine performance

2020 ◽  
pp. 095765092090627 ◽  
Author(s):  
Uyioghosa Igie ◽  
Marco Abbondanza ◽  
Artur Szymański ◽  
Theoklis Nikolaidis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Ratio ◽  
Engine Performance ◽  
Compressed Air ◽  
Design Stage ◽  
Simulation Code ◽  
Ratio Distribution ◽  
Stall Margin ◽  
Industrial Gas Turbines

Industrial gas turbines are now required to operate more flexibly as a result of incentives and priorities given to renewable forms of energy. This study considers the extraction of compressed air from the gas turbine; it is implemented to store heat energy at periods of a surplus power supply and the reinjection at peak demand. Using an in-house engine performance simulation code, extractions and injections are investigated for a range of flows and for varied rear stage bleeding locations. Inter-stage bleeding is seen to unload the stage of extraction towards choke, while loading the subsequent stages, pushing them towards stall. Extracting after the last stage is shown to be appropriate for a wider range of flows: up to 15% of the compressor inlet flow. Injecting in this location at high flows pushes the closest stage towards stall. The same effect is observed in all the stages but to a lesser magnitude. Up to 17.5% injection seems allowable before compressor stalls; however, a more conservative estimate is expected with higher fidelity models. The study also shows an increase in performance with a rise in flow injection. Varying the design stage pressure ratio distribution brought about an improvement in the stall margin utilized, only for high extraction.

A High-Fidelity Real-Time Simulation Code of Gas Turbine Dynamics for Control Applications

2002 ◽  
Author(s):  
S. M. Camporeale ◽  
B. Fortunato ◽  
M. Mastrovito
Keyword(s):  
Mathematical Model ◽  
Real Time ◽  
Gas Turbine ◽  
Dynamic Behavior ◽  
Computational Time ◽  
High Fidelity ◽  
Simulation Code ◽  
Real Time Simulation ◽  
Time Simulation ◽  
The Mathematical Model

A novel high-fidelity real-time simulation code based on a lumped, non-linear representation of gas turbine components is presented. The aim of the work is to develop a general-purpose simulation code useful for setting up and testing control equipments. The mathematical model and the numerical procedure are specially developed in order to efficiently solve the set of algebraic and ordinary differential equations that describe the dynamic behavior of the gas turbine engine. The paper presents the model and the adopted solver procedure. The code, developed in Matlab-Simulink using an object-oriented approach, is flexible and can be easily adapted to any kind of plant configuration. For high-fidelity purposes, the mathematical model takes into account the actual composition of the working gases and the variation of the specific heats with the temperature, including a stage-by-stage model of the air-cooled expansion. Simulation tests of the transients after load rejection have been carried out for a single-shaft heavy-duty gas turbine and a double-shaft industrial engine. Time plots of the main variables that describe the gas turbine dynamic behavior are shown and the results regarding the computational time per time step are discussed.

Dynamic Behaviour of a Vertical Natural Circulation Two Pressure Stage HRSG Behind a Heavy Duty Gas Turbine

2000 ◽  
Author(s):  
Georg N. Stamatelopoulos ◽  
Karl Ponweiser ◽  
Heimo Walter ◽  
Wladimir Linzer ◽  
Hubert Neßler ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Behaviour ◽  
Natural Circulation ◽  
Operational Reliability ◽  
Combined Cycle ◽  
Thermal Engineering ◽  
Simulation Code ◽  
Pressure Stage ◽  
Cold Starts

Modern combined cycle gas turbines are highly flexible in their operation, concerning start up, load change and shut down. Heat Recovery Steam Generators (HRSG) arranged downstream of the Gas Turbine (GT) are forced to operate in such a way, that the gas turbine operation is not restricted by them. Therefore, they should be designed for a high cycling capability with typical values in the range of 200 to 250 cold starts, 1000 warm and 2500 hot starts for their typical 25 year life span. Cold starts are defined as a standstill period of over 120 hours, warm starts to a weekend shutdown and hot starts to an overnight shut down. AE Energietechnik GmbH (AE), a Babcock Borsig Power company has specialized in designing, erecting and commissioning vertical natural circulation multiple pressure stage HRSGs. The vertical design combines simplicity and low investment costs with performance reliability and high availability. In order to forecast the dynamic behaviour of such a HRSG, AE has supported the development of a dynamic simulation code at the Institute of Thermal Engineering (ITW) located at the Vienna University of Technology. This finite volume code enables the prediction of velocities, pressures and temperatures for several dynamic processes of the HRSG. In the present paper computational results of starts and load changes will be presented for a vertical natural circulation HRSG. Furthermore, several design optimization changes which where made in order to increase operational reliability and availability will be demonstrated. Finally, practical applications of already constructed HRSG will be discussed and conclusions will be drawn.

Thermodynamic Performance Analyses of Mixed Gas-Steam Cycle (1): Performance Prediction Method

1998 ◽  
Author(s):  
Kirk Hanawa
Keyword(s):  
Gas Turbine ◽  
Performance Prediction ◽  
Gas Turbines ◽  
Prediction Method ◽  
Design Stage ◽  
Inlet Temperature ◽  
Evaluation Tool ◽  
Operational Parameters ◽  
Mixed Gas ◽  
Linear Differential

There are various papers relevant to the improvement ideas of gas turbine cycles, which in general discuss only optimum one-point cycle analysis.*1,*2,*6 It is, accordingly, unclear whether such improvement concepts can be applied into existing gas turbines or not. It might be difficult to incorporate such ideas, in the case of yielding significant changes for operation modes. And it may be essential to assess improvement ideas, from view points of applicability to existing gas turbine models.*3 This paper introduces the performance analysis method of simplified small perturbation procedure, showing thermodynamic behaviors based upon the component characteristics, and resultant influences due to settled operation parameters, like ambient temperature & pressure, turbine inlet temperature, etc. The established method might be used as a rule of thumb for the performance prediction when introducing water and/or steam injection into GTs, where operational parameters’ changes are defined under multi-linear differential equations. This is easy to compile in the computer as Lotus 1-2-3 or Exel to evaluate whether every parameter is within the limit or not, offering very helpful performance evaluation tool for the conceptual design stage.

Wheel Box Test Aeromechanical Verification of New First Stage Bucket With Integrated Cover Plates for MS5002 GT

2019 ◽  
Author(s):  
Marco Mariottini ◽  
Nicola Pieroni ◽  
Pietro Bertini ◽  
Beniamino Pacifici ◽  
Alessandro Giorgetti
Keyword(s):  
Gas Turbine ◽  
Oil And Gas ◽  
Oil And Gas Industry ◽  
Response Assessment ◽  
Operating Conditions ◽  
Analytical Models ◽  
Gas Industry ◽  
Improved Performance ◽  
Cover Plates

Abstract In the oil and gas industry, manufacturers are continuously engaged in providing machines with improved performance, reliability and availability. First Stage Bucket is one of the most critical gas turbine components, bearing the brunt of very severe operating conditions in terms of high temperature and stresses; aeromechanic behavior is a key characteristic to be checked, to assure the absence of resonances that can lead to damage. Aim of this paper is to introduce a method for aeromechanical verification applied to the new First Stage Bucket for heavy duty MS5002 gas turbine with integrated cover plates. This target is achieved through a significantly cheaper and streamlined test (a rotating test bench facility, formally Wheel Box Test) in place of a full engine test. Scope of Wheel Box Test is the aeromechanical characterization for both Baseline and New bucket, in addition to the validation of the analytical models developed. Wheel Box Test is focused on the acquisition and visualization of dynamic data, simulating different forcing frequencies, and the measurement of natural frequencies, compared with the expected results. Moreover, a Finite Elements Model (FEM) tuning for frequency prediction is performed. Finally, the characterization of different types of dampers in terms of impact on frequencies and damping effect is carried out. Therefore, in line with response assessment and damping levels estimation, the most suitable damper is selected. The proposed approach could be extended for other machine models and for mechanical audits.

Fracture Failure Mechanism Analysis of LP Second Stage Blades of a Gas Turbine

2014 ◽  
Vol 492 ◽  
pp. 76-85
Author(s):  
Ben Wu Liu ◽  
Jian Jun Wang ◽  
Hui Yi Yuan
Keyword(s):  
Gas Turbine ◽  
Structure Design ◽  
Structure Characteristic ◽  
Mechanism Analysis ◽  
Compressor Blades ◽  
Manufacturing Defects ◽  
Root Cause ◽  
Second Stage ◽  
Fracture Failure ◽  
Metallurgical Structure

To systematically study the root cause of the fracture failure on a gas turbine LP(low pressure) second stage blade, the damage impression, fractography, material composition and metallurgical structure of the fractured section were studied. Vibration characteristic calcultaion analysis to the blade was performed under considering the working condition and structure characteristic. The analysis results revealed that the LP second stage Blade fracture is high cycled fracture (HCF), and mainly caused by furrowed manufacturing defects close to the fatigue source. Preventive measures were presented accordingly. The studied work is valuable for being a reference to fracture failure analysis and structure design for gas compressor blades.

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