Numerical Analysis of Dilution Holes Deterioration Impacting the Performance of a V2500 Combustor

2020 ◽  
Author(s):  
Marco Konle ◽  
Ludovic de Guillebon ◽  
Lukas Schäflein
Keyword(s):  
Film Cooling ◽  
Operation Time ◽  
Test Cases ◽  
Air Jets ◽  
Individual Variations ◽  
Wide Range ◽  
Aero Engine ◽  
High Level ◽  
The Impact ◽  
Combustor Liner

Abstract In aero engine combustors, dilution air jets are used to additionally tailor the temperature field, the emissions, and the turbine inlet profile. These jets are entering the combustion chamber at different axial and circumferential locations through dedicated holes in the combustor liners. By deterioration, the diameters of these holes can significantly change over operation time. To evaluate the impact of such deterioration in the MRO context, the authors created a numerical model of a V2500 aero engine combustor and analyzed the impact. The data of dilution holes deterioration is based on the nominal design according the engine manual and the deviation measured for three engine combustors during maintenance inspection. The processes inside an aero engine combustor are very complex. To achieve most reliable information, a multi-physics approach was chosen for this evaluation. Validated in the past with a wide range of different academic test cases as well as industrial combustor test rigs, the evaluation allows conclusive analyses of the described deterioration. Back-to-back comparisons of individual variations reveals the most significant dilution holes row and give information about potential local shifts in combustor liner heat loads as well as in the exit profiles. Especially the distortion of the film cooling by the local interaction with the dilution jets could be observed. Since the deterioration of the dilution holes measured for the three combustors inspected is very small compared to the nominal design, the authors payed a lot of attention also on analyzing the model sensitivity. Increasing the spatial resolution, the plausibility of the numerical results were checked by analyzing the flow splits and the dilution jets penetration. The final step was the variation of the dilution holes individually and combined and the evaluation of resulting temperature distribution at the combustor liners and changes in the exit profile. Due to the fact that a multi-physics solver developed in the framework of OpenFOAM could be used, the authors could do these quite intensive CFD studies highly parallelized and, thus, in an acceptable time. The scalability of the solver reported already in former publications could be shown also in this application to the real engine combustor with a high level of complexity.

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1979 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

Account of Film Turbulence for Predicting Film Cooling Effectiveness in Gas Turbine Combustors

1980 ◽  
Vol 102 (3) ◽  
pp. 524-534 ◽  
Author(s):  
G. J. Sturgess
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Engine Combustion ◽  
Turbulence Effects ◽  
The Impact ◽  
Combustor Liner

The paper deals with a small but important part of the overall gas turbine engine combustion system and continues earlier published work on turbulence effects in film cooling to cover the case of film turbulence. Film cooling of the gas turbine combustor liner imposes certain geometric limitations on the coolant injection device. The impact of practical film injection geometry on the cooling is one of increased rates of film decay when compared to the performance from idealized injection geometries at similar injection conditions. It is important to combustor durability and life estimation to be able to predict accurately the performance obtainable from a given practical slot. The coolant film is modeled as three distinct regions, and the effects of injection slot geometry on the development of each region are described in terms of film turbulence intensity and initial circumferential non-uniformity of the injected coolant. The concept of the well-designed slot is introduced and film effectiveness is shown to be dependent on it. Only slots which can be described as well-designed are of interest in practical equipment design. A prediction procedure is provided for well-designed slots which describes growth of the film downstream of the first of the three film regions. Comparisons of predictions with measured data are made for several very different well-designed slots over a relatively wide range of injection conditions, and good agreement is shown.

scholarly journals Thoughts Unlocked by Technology—a Survey in Germany About Brain-Computer Interfaces

NanoEthics ◽  
2021 ◽  
Author(s):  
J. R. Schmid ◽  
O. Friedrich ◽  
S. Kessner ◽  
R. J. Jox
Keyword(s):  
Online Survey ◽  
Brain Activity ◽  
Disruptive Technology ◽  
Human Machine Interaction ◽  
Initial Development ◽  
Wide Range ◽  
Classic Form ◽  
The One ◽  
High Level ◽  
The Impact

AbstractA brain-computer interface (BCI) is a rapidly evolving neurotechnology connecting the human brain with a computer. In its classic form, brain activity is recorded and used to control external devices like protheses or wheelchairs. Thus, BCI users act with the power of their thoughts. While the initial development has focused on medical uses of BCIs, non-medical applications have recently been gaining more attention, for example in automobiles, airplanes, and the entertainment context. However, the attitudes of the general public towards BCIs have hardly been explored. Among the general population in Germany aged 18–65 years, a representative online survey with 20 items was conducted in summer 2018 (n = 1000) and analysed by descriptive statistics. The survey assessed: affinity for technology; previous knowledge and experience concerning BCIs; the attitude towards ethical, social and legal implications of BCI use and demographic information. Our results indicate that BCIs are a unique and puzzling way of human–machine interaction. The findings reveal a positive view and high level of trust in BCIs on the one hand but on the other hand a wide range of ethical and anthropological concerns. Agency and responsibility were clearly attributed to the BCI user. The participants’ opinions were divided regarding the impact BCIs have on humankind. In summary, a high level of ambivalence regarding BCIs was found. We suggest better information of the public and the promotion of public deliberation about BCIs in order to ensure responsible development and application of this potentially disruptive technology.

Application of Reliability Based Design and Assessment to Maintenance and Protection Decisions for Natural Gas Pipelines

2010 ◽  
Author(s):  
Maher Nessim ◽  
Howard Yue ◽  
Joe Zhou
Keyword(s):  
Public Awareness ◽  
Test Cases ◽  
Natural Gas Pipelines ◽  
Reliability Based Design ◽  
Wide Range ◽  
Awareness Programs ◽  
Detailed Assessment ◽  
Pipeline Failure ◽  
The Impact ◽  
Practical Implications

This paper describes a detailed assessment that was carried out to investigate the practical implications of using the Reliability Based Design and Assessment (RBDA) methodology, as described in Annex O of CSA Z662, as a basis for evaluating existing pipelines and making decisions on maintenance planning and damage prevention strategies. Two key pipeline failure threats are addressed, namely corrosion and equipment impact. The assessment was based on a number of test cases covering a wide range of diameters, grades, pressures, location classes and corrosion severities. The reliability levels associated with these cases were calculated as a function of time and compared to the reliability targets. Cases that did not meet the targets were re-analyzed with increasingly enhanced maintenance measures until the targets were met. Maintenance actions considered included higher maintenance frequencies and more stringent repair criteria for corrosion, and enhancements to such parameters as right-of-way patrol frequency and condition, public awareness programs and dig notification response for equipment impact. The results demonstrate that the reliability targets can be met through the implementation of reasonable and practical maintenance measures for the cases considered. The impact of using RBDA on the expected failure rates is discussed. In addition, the diameter and class ranges of pipelines requiring enhanced maintenance over the current norm are identified.

Experimental Investigation of the Flow Field and the Heat Transfer on a Scaled Cooled Combustor Liner With Realistic Swirling Flow Generated by a Lean-Burn Injection System

2014 ◽  
Author(s):  
Antonio Andreini ◽  
Gianluca Caciolli ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Fabio Turrini
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Film Cooling ◽  
Swirling Flow ◽  
Injection System ◽  
Lean Burn ◽  
Real Geometry ◽  
Slot Film Cooling ◽  
The Impact ◽  
Combustor Liner

Lean burn swirl stabilized combustors represent the key technology to reduce NOx emissions in modern aircraft engines. The high amount of air admitted through a lean-burn injection system is characterized by very complex flow structures such as recirculations, vortex breakdown and processing vortex core, that may deeply interact in the near wall region of the combustor liner. This interaction and its effects on the local cooling performance make the design of the cooling systems very challenging, accounting for the design and commission of new test rigs for detailed analysis. The main purpose of the present work is the characterization of the flow field and the wall heat transfer due to the interaction of a swirling flow coming out from real geometry injectors and a slot cooling system which generates film cooling in the first part of the combustor liner. The experimental setup consists of a non-reactive three sector planar rig in an open loop wind tunnel; the rig, developed within the EU project LEMCOTEC, includes three swirlers, whose scaled geometry reproduces the real geometry of an Avio Aero PERM (Partially Evaporated and Rapid Mixing) injector technology, and a simple cooling scheme made up of a slot injection, reproducing the exhaust dome cooling mass flow. Test were carried out imposing realistic combustor operating conditions, especially in terms of reduced mass flow rate and pressure drop across the swirlers. The flow field is investigated by means of PIV, while the measurement of the heat transfer coefficient is performed through Thermochromic Liquid Crystals steady state technique. PIV results show the behavior of flow field generated by the injectors, their mutual interaction and the impact of the swirled main flow on the stability of the slot film cooling. TLC measurements, reported in terms of detailed 2D heat transfer coefficient maps, highlight the impact of the swirled flow and slot film cooling on wall heat transfer.

scholarly journals The Use of Enhanced Nozzle Maps for Gas-Turbine Performance Modelling

2021 ◽  
Author(s):  
Aws A. Al-Akam ◽  
Theoklis Nikolaidis ◽  
David G. MacManus ◽  
Alvise Pellegrini
Keyword(s):  
Three Dimensional ◽  
Flow Characteristics ◽  
Engine Performance ◽  
Exhaust System ◽  
Limited Range ◽  
Performance Modelling ◽  
Essential Components ◽  
Wide Range ◽  
Aero Engine ◽  
The Impact

Abstract The use of a simulation tool to predict the aero-engine performance before committing to a final engine design has become one of the most cost-saving approaches in this field. However, most of these tools are based on low fidelity thermodynamic models, which are incapable of fully capturing the impact of three-dimensional flow characteristics. An aero-engine exhaust-system is one of the essential components that affect the engine performance. Currently, engine performance models tend to utilize simplified nozzle performance maps. These maps typically provide information over a very limited range of nozzle geometries, which may not apply to the wide range of architectures and designs of aeroengines. The current paper presents a methodology for the development of nozzle performance maps, which takes into account the aerodynamic and the geometric parameters of the nozzle design. The methodology is based on the reduced-order models. These models are integrated into a zero-dimensional engine performance code to improve the accuracy of its thrust calculation. The impact of the new thrust model on the overall engine performance and the operating point is analysed and discussed. The results showed that the implementation of the modified maps, which take into account the flow characteristics and the geometry of the nozzle, affects the thrust calculation. In a typical case of a turbofan operating at cruise conditions, the net thrust estimation with the modified nozzle maps showed a difference of 0.2%, compared with the simple nozzle maps. The new thrust calculation method has the advantage in capturing the multidimensional impact of the flow of the nozzle as compared with the conventional one. Furthermore, the implementation of the new method reduces the uncertainties introduced by a simplified nozzle model and, consequently, it can support the decision-making process in the design of the engine.

The impact of professional capital on educational excellence and equality in Estonia

2016 ◽  
Vol 1 (3) ◽  
pp. 237-252 ◽  
Author(s):  
Maie Kitsing ◽  
Alan Boyle ◽  
Hasso Kukemelk ◽  
Jaan Mikk
Keyword(s):  
Education System ◽  
International Student ◽  
Student Assessment ◽  
General Level ◽  
Content Type ◽  
Professional Capital ◽  
International Student Assessment ◽  
Wide Range ◽  
High Level ◽  
The Impact

Purpose – Estonia’s results in programme for international student assessment (PISA) studies between 2006 and 2012 showed both high-level attainment and social equity. The combination of excellence and equity makes Estonia stand out from other countries. The purpose of this paper is to explore the wide range of factors that influence Estonian students’ performance in these tests and note how professional capital fits into the overall picture. Design/methodology/approach – First the authors present a brief analysis of the outcomes in terms of the PISA results. Then the authors describe a wide range of contextual factors in Estonia such as: the country’s general level of human development; historical and cultural factors; demographics and social factors. These are the inputs to the education system. Finally the authors explore the interplay between features of the education system itself – the schooling processes – and note the impact of professional capital. Findings – The authors judge that the interplay between professional capital with other factors that work in harmony explains why the system is highly effective. This coherence is not accidental; it is the outcome of a series of deliberate reforms and investment over a single generation. Originality/value – Between 2009 and 2012 Estonia increased its share of top performers in PISA tests while, at the same time, reduced the proportion of low performers. This is commonly referred to as “raising the bar and closing the gap”. Individual schools struggle to close attainment gaps between different groups of students. Estonia is one of a very small number of countries to achieve both excellence and equality across the whole national system.

Experimental and Theoretical Investigation of Thermal Effectiveness in Multiperforated Plates for Combustor Liner Effusion Cooling

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Alessio Picchi ◽  
Lorenzo Tarchi ◽  
Fabio Turrini
Keyword(s):  
Film Cooling ◽  
Cooling System ◽  
Fluid Dynamic ◽  
Density Ratio ◽  
Heat Removal ◽  
Correlative Analysis ◽  
Pattern Shape ◽  
The Impact ◽  
Combustor Liner ◽  
Overall Effectiveness

State-of-the-art liner cooling technology for modern combustors is represented by effusion cooling (or full-coverage film cooling). Effusion is a very efficient cooling strategy based on the use of multiperforated liners, where the metal temperature is lowered by the combined protective effect of the coolant film and heat removal through forced convection inside each hole. The aim of this experimental campaign is the evaluation of the thermal performance of multiperforated liners with geometrical and fluid-dynamic parameters ranging among typical combustor engine values. Results were obtained as the adiabatic film effectiveness following the mass transfer analogy by the use of pressure sensitive paint, while the local values of the overall effectiveness were obtained by eight thermocouples housed in as many dead holes about 2 mm below the investigated surface. Concerning the tested geometries, different porosity levels were considered: such values were obtained by both increasing the hole diameter and pattern spacing. Then the effect of the hole inclination and aspect ratio pattern shape were tested to assess the impact of typical cooling system features. Seven multiperforated planar plates, reproducing the effusion arrays of real combustor liners, were tested, imposing six blowing ratios in the range 0.5–5. Additional experiments were performed in order to explore the effect of the density ratio (DR=1;1.5) on the film effectiveness. Test samples were made of stainless steel (AISI304) in order to achieve the Biot number similitude for the overall effectiveness tests. To extend the validity of the survey a correlative analysis was performed to point out, in an indirect way, the augmentation of the hot side heat transfer coefficient due to effusion jets. Finallyv,in order to address the thermal behavior of the different geometries in the presence of gas side radiation, additional simulations were performed considering different levels of radiative heat flux.

Effect of Hole Geometry on the Thermal Performance of Fan-Shaped Film Cooling Holes

2005 ◽  
Vol 127 (4) ◽  
pp. 718-725 ◽  
Author(s):  
Michael Gritsch ◽  
Will Colban ◽  
Heinz Schär ◽  
Klaus Döbbeling
Keyword(s):  
Thermal Performance ◽  
Film Cooling ◽  
Density Ratio ◽  
Geometrical Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Wide Range ◽  
Cooling Hole ◽  
Hole Geometry ◽  
The Impact

This study evaluates the impact of typical cooling hole shape variations on the thermal performance of fan-shaped film holes. A comprehensive set of experimental test cases featuring 16 different film-cooling configurations with different hole shapes have been investigated. The shape variations investigated include hole inlet-to-outlet area ratio, hole coverage ratio, hole pitch ratio, hole length, and hole orientation (compound) angle. Flow conditions applied cover a wide range of film blowing ratios M=0.5 to 2.5 at an engine-representative density ratio DR=1.7. An infrared thermography data acquisition system is used for highly accurate and spatially resolved surface temperature mappings. Accurate local temperature data are achieved by an in situ calibration procedure with the help of thermocouples embedded in the test plate. Detailed film-cooling effectiveness distributions and discharge coefficients are used for evaluating the thermal performance of a row of fan-shaped film holes. An extensive variation of the main geometrical parameters describing a fan-shaped film-cooling hole is done to cover a wide range of typical film-cooling applications in current gas turbine engines. Within the range investigated, laterally averaged film-cooling effectiveness was found to show only limited sensitivity from variations of the hole geometry parameters. This offers the potential to tailor the hole geometry according to needs beyond pure cooling performance, e.g., manufacturing facilitations.

scholarly journals HUMAN RESOURCES MANAGEMENT OF HEI THROUGH THE FORMATION OF EFFECTIVE HR POLICY

2020 ◽  
Vol 5 (158) ◽  
pp. 58-63
Author(s):  
N. Mushchynska ◽  
N. Matvieieva
Keyword(s):  
Higher Education ◽  
Human Resources ◽  
Teacher Development ◽  
Human Resources Management ◽  
Future Research ◽  
Resources Management ◽  
Wide Range ◽  
Constructive Work ◽  
High Level ◽  
The Impact

There is a dearth of research in literature examining how people are managed in higher education institu-tions in Ukraine. This paper explores how universities manage their traditional personnel management system. The problems of formation of HR policy of the institution of higher education (HEI) in the context of its main direc-tions are investigated. In the conditions of critical lack of financial resources, the organizational bases to in-crease the efficiency of application of HRM system in HEI are considered. Our findings reveal some steps to help HEI in their long way to establish a modern HRM system. The basic perspective research directions which will allow implementing modern concepts of HRM in the academic environ-ment are proposed. Among them are rejection of the paradigm student - graduate student - teacher within one HEI and assessment of scientific and pedagogical staff through 3 blocks: effectiveness; competence; potential for teacher development. The need and implications for future research are identified. The most perspective is the role of the positive OCB (Organisational Citizenship Behaviour) as a wide range of individual actions that go beyond assigned tasks because it is associated with constructive work that employees do of their own choice and benefits the company. As an effective motivational tool could be used the perception of the impact of different types of re-search and learning support by different categories of participants in the educational and scientific environment. It is also recommended to pay special attention to the creation of a high level of employee loyalty. The insights from this study would be of value to the management of universities. Keywords: human resources policy (HR policy), human resources management (HRM), institution of higher education (HEI).

Sign in / Sign up

Export Citation Format

Share Document