Towards Visualisation of Capacity, Bearing Thrust Load and Reaction Variation With Aerofoil Skew in a Gas Turbine

2019 ◽  
Author(s):  
Karthik Srinivasan ◽  
Soumyik K. Bhaumik ◽  
Lakshmanan Valliappan
Keyword(s):  
Gas Turbines ◽  
System Level ◽  
Skew Angle ◽  
Small Deviations ◽  
Pressure Drops ◽  
Performance Targets ◽  
Multi Stage ◽  
The Individual ◽  
The Impact ◽  
Thrust Load

Abstract The requirements in the design of aerofoils for gas turbines are not limited to only meeting the aerothermal performance. A typical scenario for a turbine is to understand the impact of aerofoil skew on capacity, reaction and bearing thrust load. A means to achieve the target capacity could be by skewing the aerofoil. This, however, changes the stage reaction which in turn impacts the bearing thrust load. In the case of a multi stage turbine, the work split between the stages impacts the ratio of pressure drops and hence the contribution of the individual aerofoil rows to the overall capacity and bearing thrust load variation. This paper deals with a generic approach to visualise the variation of capacity and bearing thrust load with aerofoil skew for a stage of interest along with the Constraints that could be potentially imposed on the stage. This methodology provides a useful mapping between parameters which are directly under the aerodynamicist’s control (i.e. aerofoil skew) to module- and system-level behaviours (i.e. capacity, bearing thrust load). It thereby allows informed choices to be made throughout the design process which deliver the turbine aerodynamic performance targets whilst respecting wider system-level constraints. Suitable optimisation within this design space will yield a design that is fundamentally robust to small deviations in skew angle. Additionally, qualitative variation of the gas path static pressure and reaction based on aerofoil skews are explained pictorially to facilitate the understanding.

Life Prediction of Power Turbine Components for High Exhaust Back Pressure Applications: Part I — Disks

2015 ◽  
Author(s):  
Dipankar Dua ◽  
Brahmaji Vasantharao
Keyword(s):  
Steady State ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Life Prediction ◽  
Creep Damage ◽  
Back Pressure ◽  
System Level ◽  
Cyclic Life ◽  
Power Turbine ◽  
The Impact

Industrial and aeroderivative gas turbines when used in CHP and CCPP applications typically experience an increased exhaust back pressure due to pressure losses from the downstream balance-of-plant systems. This increased back pressure on the power turbine results not only in decreased thermodynamic performance but also changes power turbine secondary flow characteristics thus impacting lives of rotating and stationary components of the power turbine. This Paper discusses the Impact to Fatigue and Creep life of free power turbine disks subjected to high back pressure applications using Siemens Energy approach. Steady State and Transient stress fields have been calculated using finite element method. New Lifing Correlation [1] Criteria has been used to estimate Predicted Safe Cyclic Life (PSCL) of the disks. Walker Strain Initiation model [1] is utilized to predict cycles to crack initiation and a fracture mechanics based approach is used to estimate propagation life. Hyperbolic Tangent Model [2] has been used to estimate creep damage of the disks. Steady state and transient temperature fields in the disks are highly dependent on the secondary air flows and cavity dynamics thus directly impacting the Predicted Safe Cyclic Life and Overall Creep Damage. A System-level power turbine secondary flow analyses was carried out with and without high back pressure. In addition, numerical simulations were performed to understand the cavity flow dynamics. These results have been used to perform a sensitivity study on disk temperature distribution and understand the impact of various back pressure levels on turbine disk lives. The Steady Sate and Transient Thermal predictions were validated using full-scale engine test and have been found to correlate well with the test results. The Life Prediction Study shows that the impact on PSCL and Overall Creep damage for high back pressure applications meets the product design standards.

scholarly journals Comparison between 1-D and grey-box models of a SOFC

2019 ◽  
Vol 128 ◽  
pp. 01007
Author(s):  
Ramin Moradi ◽  
Andrea Di Carlo ◽  
Federico Testa ◽  
Luca Del Zotto ◽  
Enrico Bocci ◽  
...  
Keyword(s):  
Power Systems ◽  
Solid Electrolyte ◽  
Gas Turbines ◽  
Internal Combustion Engines ◽  
Box Model ◽  
System Level ◽  
Internal Temperature ◽  
Box Models ◽  
The Impact ◽  
D Model

Solid Oxide Fuel Cells (SOFCs) have shown unique performance in terms of greater electrical efficiency and thermochemical integrity with the power systems compared to gas turbines and internal combustion engines. Nonetheless, simple and reliable models still must be defined. In this paper, a comparisonbetween a grey-box model and a 1-D model of a SOFC is performed to understand the impact of the heat transfer inside the cell on the internal temperature distribution of the solid electrolyte. Hence, a significant internal temperature peak of the solid electrolyte is observed for a known difference between anode and cathode inlet temperatures. Indeed, it highlights the difference between the 1-D model andthe grey-box model regarding the thermal conditioning of the SOFC. Therefore, the results of this study can be used to investigate the reliability of the thermal results of box models in system-level simulations.

VP07 Collaboratively Modelling The Impact Of Interventions Retrospectively

2017 ◽  
Vol 33 (S1) ◽  
pp. 149-149
Author(s):  
Gordon Bache ◽  
Sukh Tatla ◽  
Deborah Simpson
Keyword(s):  
Real World ◽  
Real Data ◽  
System Level ◽  
Local Data ◽  
Real World Data ◽  
Total Saving ◽  
Retrospective Assessment ◽  
Administration Time ◽  
The Individual ◽  
The Impact

INTRODUCTION:A conventional approach to communicating value is to model the budget impact of a medicine and the associated formulations in which it is available to be prescribed. However, such an approach does not demonstrate the actual realization of the proposed impact. This abstract outlines an approach to presenting retrospective data back to healthcare professionals (HCP) that blends assumptions and real-world data. For illustrative purposes, we present the results of an application of the model for subcutaneously delivered trastuzumab in an anonymized trust in Yorkshire and Humber.METHODS:The authors developed a model that examined one calendar year (from April 2014) of redistributed sales data for both the intravenous and subcutaneous formulations of trastuzumab for every National Health Service (NHS) trust in England. A series of baseline assumptions (1) were used to model the resource impact of different formulations such as chair time, HCP time, pharmacy preparation time, consumables, wastage, and other considerations. Impacts were estimated at the individual attendance level and scaled to the caseload. These baseline assumptions could then be overwritten by the individual trust using local data.RESULTS:The site delivered approximately 985 doses of subcutaneous trastuzumab over a period of 12 months from April 2014, which represented about 76 percent of the total number of doses delivered. Chair time is estimated to have reduced by 22 minutes per attendance, resulting in a total saving of 361hours. HCP administration time is estimated to have reduced by 23 minutes per attendance, resulting in a total saving of 378 hours based on changing 985 IV doses to SC therapy.CONCLUSIONS:Blending real data and assumptions to provide a retrospective assessment of actual benefits realized back to HCPs is a powerful tool for demonstrating real-world value at both an individual trust and system level.

Thermo-Fluid Modelling for Gas Turbines—Part I: Theoretical Foundation and Uncertainty Analysis

2009 ◽  
Author(s):  
Konstantinos G. Kyprianidis ◽  
Vishal Sethi ◽  
Stephen O. T. Ogaji ◽  
Pericles Pilidis ◽  
Riti Singh ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Simulation Software ◽  
System Level ◽  
Fluid Models ◽  
Performance Simulation ◽  
Turbine Performance ◽  
Aircraft System ◽  
The Impact ◽  
Made In

In this two-part publication, various aspects of thermo-fluid modelling for gas turbines are described and their impact on performance calculations and emissions predictions at aircraft system level is assessed. Accurate and reliable fluid modelling is essential for any gas turbine performance simulation software as it provides a robust foundation for building advanced multi-disciplinary modelling capabilities. Caloric properties for generic and semi-generic gas turbine performance simulation codes can be calculated at various levels of fidelity; selection of the fidelity level is dependent upon the objectives of the simulation and execution time constraints. However, rigorous fluid modelling may not necessarily improve performance simulation accuracy unless all modelling assumptions and sources of uncertainty are aligned to the same level. Certain modelling aspects such as the introduction of chemical kinetics, and dissociation effects, may reduce computational speed and this is of significant importance for radical space exploration and novel propulsion cycle assessment. This paper describes and compares fluid models, based on different levels of fidelity, which have been developed for an industry standard gas turbine performance simulation code and an environmental assessment tool for novel propulsion cycles. The latter comprises the following modules: engine performance, aircraft performance, emissions prediction, and environmental impact. The work presented aims to fill the current literature gap by: (i) investigating the common assumptions made in thermo-fluid modelling for gas turbines and their effect on caloric properties and (ii) assessing the impact of uncertainties on performance calculations and emissions predictions at aircraft system level. In Part I of this two-part publication, a comprehensive analysis of thermo-fluid modelling for gas turbines is presented and the fluid models developed are discussed in detail. Common technical models, used for calculating caloric properties, are compared while typical assumptions made in fluid modelling, and the uncertainties induced, are examined. Several analyses, which demonstrate the effects of composition, temperature and pressure on caloric properties of working mediums for gas turbines, are presented. The working mediums examined include dry air and combustion products for various fuels and H/C ratios. The errors induced by ignoring dissociation effects are also discussed.

Does training change practice? A survey of clinicians and managers one year after training in trauma-informed care

2017 ◽  
Vol 12 (3) ◽  
pp. 188-198 ◽  
Author(s):  
Theresa Maureen Williams ◽  
Geoffrey Paul Smith
Keyword(s):  
Mental Health ◽  
Behaviour Change ◽  
System Level ◽  
Content Type ◽  
Trauma Informed Care ◽  
Trauma Informed ◽  
One Year ◽  
The Individual ◽  
The Impact ◽  
Drug And Alcohol

Purpose The purpose of this paper is to describe the impact of a trauma-informed care (TIC) training programme on practice at the individual and workplace level in mental health and drug and alcohol services and to examine the implications of using training alone as a strategy for achieving system-level practice change. Design/methodology/approach A total of 271 clinicians and managers from public mental health and drug and alcohol services in Western Australia who had undertaken TIC training were invited to complete an on-line survey 12 months after training. Individual survey items were based on a five-point Likert scale with opportunity being provided for additional comments from respondents. Findings One year post-training, both clinicians and managers reported that training had increased their awareness and knowledge and had a positive impact on their attitudes towards TIC. Clinicians reported a moderate impact on their individual practice and both groups reported very limited success in bringing about change in their workplaces. Workforce development and organisational factors were identified by both clinicians and managers as being barriers to implementation. Research limitations/implications Only 30 per cent of the training participants responded to the survey and it is not possible to determine whether they differed from non-respondents. Findings were based on a self-report survey with no objective measure of behaviour change. Originality/value This “naturalistic” study examines the longer-term impact of training, from the perspective of clinicians and managers, on changing practice at the individual clinician and workplace level. It highlights the critical importance of understanding and addressing contextual factors where collective, coordinated behaviour change is needed in order to effect organisational change.

Human Factoring Healthcare

2014 ◽  
Vol 3 (1) ◽  
pp. 191-195 ◽  
Author(s):  
Kristen Miller ◽  
Tandi Bagian ◽  
Linda Williams
Keyword(s):  
Patient Safety ◽  
Adverse Events ◽  
Human Factors ◽  
Human Error ◽  
System Level ◽  
Department Of Veterans Affairs ◽  
Just Culture ◽  
Safe Patient Care ◽  
The Individual ◽  
The Impact

Even in a just culture, preventable or avoidable adverse events can often be attributed to a failure to follow recognized, evidence-based best practices or guidelines at the individual and/or system level. Investigations of adverse events have heightened the awareness of the need to redesign systems and processes to prevent human error. Despite the existence of considerable information about how to improve care through the application of human factors, healthcare professionals are not provided a means to ensure sufficient education in healthcare human factors and the impact on patient safety. Additionally, even when existing knowledge is taught, providers are challenged to translate and apply knowledge to affect safe patient care. The Department of Veterans Affairs (VA) National Center for Patient Safety (NCPS) Healthcare Human Factors Modules were designed to address these challenges by combining dissemination of existing knowledge and recent research into accessible, hands-on activities that drive home human factors and patient safety competencies. These modules represent an innovative and engaging way to allow providers and administrators alike the ability to advance the shift to systems thinking through high-impact education.

scholarly journals Student engagement, non-completion and pedagogy: Development of a measurement tool

2017 ◽  
Vol 61 (1) ◽  
pp. 40-53 ◽  
Author(s):  
Nicky Dulfer ◽  
Suzanne Rice ◽  
Kira Clarke
Keyword(s):  
Student Engagement ◽  
Large Scale ◽  
Career Guidance ◽  
Small Sample ◽  
System Level ◽  
Dropping Out ◽  
Measurement Tool ◽  
Negative Consequences ◽  
The Individual ◽  
The Impact

A significant body of research documents the negative consequences of dropping out of school for both the individual and society. In attempting to respond to the problem of early school leaving, schools and systems internationally have put in place a range of system-level and local responses such as mentoring, targeted additional career guidance and homework clubs. Unfortunately, these ‘add-ons’ often stop outside the classroom door, and do not consider the impact of teaching practices on students’ engagement in school and their decisions to remain or leave. This article reports on the development of instruments aimed at measuring four constructs that have been shown to be related to student engagement and school completion, namely competence, autonomy, relatedness and an appreciation of subject relevance. Analyses of data from a small sample of Year 9 students ( N = 48) in two Australian secondary schools indicated that, with some adjustments, the research instruments developed provided reliable and valid measures of the four constructs for use in large-scale research with students.

Measurements of the Four-Quadrant Characteristics on a Multi-Stage Turbine

1980 ◽  
Vol 102 (2) ◽  
pp. 316-321 ◽  
Author(s):  
K. Bammert ◽  
P. Zehner
Keyword(s):  
Gas Turbines ◽  
Single Stage ◽  
Operation Conditions ◽  
Multi Stage ◽  
Performance Curves ◽  
Stage Performance ◽  
The Individual ◽  
Four Quadrant ◽  
Operating Points ◽  
Energy Plants

With turbines, operation conditions far from the design range are possible. With gas turbines, in nuclear and solar energy plants in the case of a fault, flow in reverse directions may even occur. For extreme operations insufficient knowledge was available, so measurements were carried out at first on a single-stage turbine and then on a seven-stage turbine, with both the mass flow and the rotor speed systematically varied in the positive (normal direction) and negative ranges (four-quadrant characteristics). The measurement on the seven-stage turbine basically tally with the single-stage measurements. Stage performance curves can be approximately calculated also for four quadrants from the cascade characteristics of the middle section. The calculated curves are compared to the results of the single-stage measurements. During operation far from the design point, the individual stages of a multi-stage turbine work at a wide variety of operating points, so the characteristics of such a turbine have to be determined by the superimposition of the corresponding stage performance curves on each other.

scholarly journals Traffic Congestion Management as a Learning Agent Coordination Problem

2009 ◽  
pp. 261-279 ◽  
Author(s):  
Kagan Tumer ◽  
Zachary T. Welch ◽  
Adrian Agogino
Keyword(s):  
Traffic Congestion ◽  
Traffic Management ◽  
Congestion Management ◽  
System Level ◽  
Multi Agent Systems ◽  
Coordination Problem ◽  
Learning Agent ◽  
Reward Functions ◽  
The Individual ◽  
The Impact

Traffic management problems provide a unique environment to study how multi-agent systems promote desired system level behavior. In particular, they represent a special class of problems where the individual actions of the agents are neither intrinsically “good” nor “bad” for the system. Instead, it is the combinations of actions among agents that lead to desirable or undesirable outcomes. As a consequence, agents need to learn how to coordinate their actions with those of other agents, rather than learn a particular set of “good” actions. In this chapter, the authors focus on problems where there is no communication among the drivers, which puts the burden of coordination on the principled selection of the agent reward functions. They explore the impact of agent reward functions on two types of traffic problems. In the first problem, the authors study how agents learn the best departure times in a daily commuting environment and how following those departure times alleviates congestion. In the second problem, the authors study how agents learn to select desirable lanes to improve traffic flow and minimize delays for all drivers. In both cases, they focus on having an agent select the most suitable action for each driver using reinforcement learning, and explore the impact of different reward functions on system behavior. Their results show that agent rewards that are both aligned with and sensitive to, the system reward lead to significantly better results than purely local or global agent rewards. They conclude this chapter by discussing how changing the way in which the system performance is measured affects the relative performance of these rewards functions, and how agent rewards derived for one setting (timely arrivals) can be modified to meet a new system setting (maximize throughput).

Upgrade of a 16-Stage Industrial Compressor: Part II — Extension of the Analysis Method to the Design Function and Results

2006 ◽  
Author(s):  
Magdy S. Attia
Keyword(s):  
Axial Compressor ◽  
Design Environment ◽  
Axial Compressors ◽  
Performance Targets ◽  
Streamline Curvature ◽  
Multi Stage ◽  
Design Function ◽  
3D Effects ◽  
Compressor Performance ◽  
The Individual

A retrofit package that includes a slightly larger inlet and new, custom diffusion airfoils (CDA) was designed to replace the 16-stage axial compressor. The method used, and presented here, builds on earlier developments and is an extension of the scheme used to predict the compressor performance (Part I). The use of results from single-row 3D CFD, and their implementation into a streamline curvature (Throughflow) code lead to a better understanding of the compressor performance, which in turn lead to a better model of the compressor. This paper shows how the role of this newly developed model has been modified and adapted to the design environment. The 3D CFD results had previously provided a more accurate representation of deviation and losses, particularly at and near the end walls. The Throughflow code, when re-converged for design purposes, generated a much different solution for the individual streamlines than had been previously calculated using correlation or S1S2 analyses. Consequently, the newly generated boundary conditions for designing the individual stream sections, such as inlet and exit Mach numbers and air angles were also quite different. The designer then embarked on tailoring the individual sections to their respective duties under the guidelines of the newly developed method in true custom diffusion fashion. Iterations were conducted to optimize the section and airfoil shapes taking into consideration 3D effects. The end result was a systematic technique for designing multi-stage axial compressors and generating 3D airfoil shapes. The retrofit compressor upgrade package achieved its performance targets and delivered a measured polytropic efficiency of 93.4%.

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