Improving Turbine Stage Efficiency and Sealing Effectiveness Through Modifications of the Rim Seal Geometry

2012 ◽  
Author(s):  
I. Popović ◽  
H. P. Hodson
Keyword(s):  
Large Scale ◽  
Outer Part ◽  
Turbine Stage ◽  
Linear Cascade ◽  
Seal Design ◽  
Swirl Velocity ◽  
Different Types ◽  
Recirculation Zones ◽  
Secondary Air ◽  
Stage Efficiency

This paper presents an investigation of a range of engine realistic rim seals starting from a simple axial seal to different types of overlapping seals. The experiments were performed in a large-scale linear cascade equipped with a secondary air system capable of varying independently both the mass fraction as well as the swirl velocity of the leakage air. The experimental results were also complemented by CFD to provide better insight in the flow physics. It has been found that the key feature of the rim seals that affect their impact on overall loss generation and their ability to provide good sealing effectiveness was the location and the size of the recirculation zones within the rim seal. The requirements for good sealing and reduced spoiling effects on the main gaspath flow often led to contradictory designs. In general, the recirculation zones were found to improve sealing by reducing the effect of the pitchwise (circumferential) variation in the pressure distribution due to the blade’s potential field, and thus reduce ingestion. However, at the same time the recirculation zones tend to increase the loss generation. The best compromise was found when the outer part of the seal and its interface with the rotor platform was as smooth as possible to minimize the spoiling losses, while the recirculation zones were confined to the inner part of the seal to maintain acceptable levels of sealing effectiveness. A new rim seal design, which utilizes the best attributes of the above mentioned designs was developed. Linear cascade tests showed the losses due to the leakage-mainstream interaction were reduced by 33% compared to the datum seal design. Further validation was performed by examining the new configuration using unsteady full-stage calculations under engine realistic conditions. These calculations suggest an improvement of nearly 0.2% in the stage efficiency.

Improving Turbine Stage Efficiency and Sealing Effectiveness Through Modifications of the Rim Seal Geometry

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
Ivan Popovíc ◽  
Howard P. Hodson
Keyword(s):  
Large Scale ◽  
Outer Part ◽  
Turbine Stage ◽  
Linear Cascade ◽  
Seal Design ◽  
Swirl Velocity ◽  
Different Types ◽  
Recirculation Zones ◽  
Secondary Air ◽  
Stage Efficiency

This paper presents an investigation of a range of engine realistic rim seals starting from a simple axial seal to different types of overlapping seals. The experiments were performed in a large-scale linear cascade equipped with a secondary air system capable of varying independently both the mass fraction as well as the swirl velocity of the leakage air. The experimental results were also complemented by computationally fluid dynamics (CFD) to provide better insight in the flow physics. It has been found that the key feature of the rim seals that affect their impact on overall loss generation and their ability to provide good sealing effectiveness was the location and the size of the recirculation zones within the rim seal. The requirements for good sealing and reduced spoiling effects on the main gaspath flow often led to contradictory designs. In general, the recirculation zones were found to improve sealing by reducing the effect of the pitchwise (circumferential) variation in the pressure distribution due to the blade's potential field, and thus reduce ingestion. However, at the same time the recirculation zones tend to increase the loss generation. The best compromise was found when the outer part of the seal and its interface with the rotor platform was as smooth as possible to minimize the spoiling losses, while the recirculation zones were confined to the inner part of the seal to maintain acceptable levels of sealing effectiveness. A new rim seal design, which utilizes the best attributes of the above mentioned designs was developed. Linear cascade tests showed the losses due to the leakage-mainstream interaction were reduced by 33% compared to the datum seal design. Further validation was performed by examining the new configuration using unsteady full-stage calculations under engine realistic conditions. These calculations suggest an improvement of nearly 0.2% in the stage efficiency.

The Effect of Secondary Air Injection on the Performance of a Transonic Turbine Stage

2002 ◽  
Author(s):  
S. Girgis ◽  
E. Vlasic ◽  
J.-P. Lavoie ◽  
S. H. Moustapha
Keyword(s):  
Turbine Stage ◽  
Cfd Simulations ◽  
Secondary Air Injection ◽  
Flow Test ◽  
Mainstream Flow ◽  
Purge Flow ◽  
Simulated Test ◽  
Transonic Turbine ◽  
Secondary Air ◽  
Stage Efficiency

This paper presents results of rig testing of a transonic, single stage turbine with various modifications made to the injection of secondary air into the mainstream. Results show that significant improvements in stage efficiency can be realized by optimizing the injection of upstream disk purge and rotor upstream shroud leakage flow into the mainstream flow. Results of CFD simulations of the rotor upstream disk purge flow test conditions and closely simulated test geometry agree well with test data.

Improving Turbine Efficiency Using Non-Axisymmetric End Walls: Validation in the Multi-Row Environment and With Low Aspect Ratio Blading

2002 ◽  
Author(s):  
N. W. Harvey ◽  
G. Brennan ◽  
D. A. Newman ◽  
M. G. Rose
Keyword(s):  
Turbine Stage ◽  
Flow Conditions ◽  
Original Design ◽  
Linear Cascade ◽  
Hp Model ◽  
Low Aspect Ratio ◽  
Turbine Efficiency ◽  
Met Expectations ◽  
End Wall ◽  
Stage Efficiency

This paper describes how the Intermediate Pressure (IP) turbine model rig of the Rolls-Royce Trent 500 engine was redesigned by applying non-axisymmetric end walls to both the vane and blade passages. The blading aerofoil shapes, the turbine operating point and the overall flow conditions were unaltered from the original design. The results from testing of the model rig are presented and compared with those obtained previously for the datum design. A feature of this is that the IP turbine was tested in a “two-shaft” arrangement with the (upstream) Trent 500 High Pressure (HP) model turbine. Previously, non-axisymmetric end wall profiling had been shown to achieve a 0.59 ± 0.25% improvement in the stage efficiency of the Trent 500 HP model turbine when tested as a single stage, Rose et al. [1]. This had exceeded the design expectation of 0.4% improvement, Brennan et al. [4] — based on previous linear cascade research at Durham University, see Harvey et al. [2] and Hartland et al. [3]. The IP and HP turbines with profiled end walls were tested together, while for the datum test both model turbines had blading with axisymmetric end walls. The results have met expectations with an improvement in the IP turbine stage efficiency of 0.9 ± 0.4% at the design point. The turbine characteristics are shown to change significantly from the datum test.

Overview of Subsynchronous Oscillation in Grid-connected Wind Farm

2020 ◽  
Vol 13 (7) ◽  
pp. 969-979
Author(s):  
Xu Pei-Zhen ◽  
Lu Yong-Geng ◽  
Cao Xi-Min
Keyword(s):  
Power Systems ◽  
Wind Turbine ◽  
Large Scale ◽  
Wind Farm ◽  
Wind Farms ◽  
Induction Generator ◽  
Future Research ◽  
Stable Operation ◽  
Subsynchronous Oscillation ◽  
Different Types

Background: Over the past few years, the subsynchronous oscillation (SSO) caused by the grid-connected wind farm had a bad influence on the stable operation of the system and has now become a bottleneck factor restricting the efficient utilization of wind power. How to mitigate and suppress the phenomenon of SSO of wind farms has become the focus of power system research. Methods: This paper first analyzes the SSO of different types of wind turbines, including squirrelcage induction generator based wind turbine (SCIG-WT), permanent magnet synchronous generator- based wind turbine (PMSG-WT), and doubly-fed induction generator based wind turbine (DFIG-WT). Then, the mechanisms of different types of SSO are proposed with the aim to better understand SSO in large-scale wind integrated power systems, and the main analytical methods suitable for studying the SSO of wind farms are summarized. Results: On the basis of results, using additional damping control suppression methods to solve SSO caused by the flexible power transmission devices and the wind turbine converter is recommended. Conclusion: The current development direction of the SSO of large-scale wind farm grid-connected systems is summarized and the current challenges and recommendations for future research and development are discussed.

Situational Breakdowns

2019 ◽  
Author(s):  
Anne Nassauer
Keyword(s):  
United States ◽  
Large Scale ◽  
Contextual Factors ◽  
The United States ◽  
Social Outcomes ◽  
Dynamic Processes ◽  
Collective Decisions ◽  
Different Types ◽  
The Impact

This book provides an account of how and why routine interactions break down and how such situational breakdowns lead to protest violence and other types of surprising social outcomes. It takes a close-up look at the dynamic processes of how situations unfold and compares their role to that of motivations, strategies, and other contextual factors. The book discusses factors that can draw us into violent situations and describes how and why we make uncommon individual and collective decisions. Covering different types of surprise outcomes from protest marches and uprisings turning violent to robbers failing to rob a store at gunpoint, it shows how unfolding situations can override our motivations and strategies and how emotions and culture, as well as rational thinking, still play a part in these events. The first chapters study protest violence in Germany and the United States from 1960 until 2010, taking a detailed look at what happens between the start of a protest and the eruption of violence or its peaceful conclusion. They compare the impact of such dynamics to the role of police strategies and culture, protesters’ claims and violent motivations, the black bloc and agents provocateurs. The analysis shows how violence is triggered, what determines its intensity, and which measures can avoid its outbreak. The book explores whether we find similar situational patterns leading to surprising outcomes in other types of small- and large-scale events: uprisings turning violent, such as Ferguson in 2014 and Baltimore in 2015, and failed armed store robberies.

scholarly journals Transcriptional and morphological profiling of parvalbumin interneuron subpopulations in the mouse hippocampus

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lin Que ◽  
David Lukacsovich ◽  
Wenshu Luo ◽  
Csaba Földy
Keyword(s):  
Large Scale ◽  
Cell Types ◽  
Rna Seq ◽  
Neuronal Identity ◽  
Parvalbumin Interneurons ◽  
Different Types ◽  
Parvalbumin Interneuron ◽  
Cam Profile ◽  
Developmental Domains

AbstractThe diversity reflected by >100 different neural cell types fundamentally contributes to brain function and a central idea is that neuronal identity can be inferred from genetic information. Recent large-scale transcriptomic assays seem to confirm this hypothesis, but a lack of morphological information has limited the identification of several known cell types. In this study, we used single-cell RNA-seq in morphologically identified parvalbumin interneurons (PV-INs), and studied their transcriptomic states in the morphological, physiological, and developmental domains. Overall, we find high transcriptomic similarity among PV-INs, with few genes showing divergent expression between morphologically different types. Furthermore, PV-INs show a uniform synaptic cell adhesion molecule (CAM) profile, suggesting that CAM expression in mature PV cells does not reflect wiring specificity after development. Together, our results suggest that while PV-INs differ in anatomy and in vivo activity, their continuous transcriptomic and homogenous biophysical landscapes are not predictive of these distinct identities.

scholarly journals FlsnRNA-seq: protoplasting-free full-length single-nucleus RNA profiling in plants

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Yanping Long ◽  
Zhijian Liu ◽  
Jinbu Jia ◽  
Weipeng Mo ◽  
Liang Fang ◽  
...  
Keyword(s):  
Single Cell ◽  
Cell Walls ◽  
Large Scale ◽  
Full Length ◽  
Cell Level ◽  
Root Cells ◽  
Rna Profiling ◽  
Different Types ◽  
Long Read ◽  
Single Nucleus

AbstractThe broad application of single-cell RNA profiling in plants has been hindered by the prerequisite of protoplasting that requires digesting the cell walls from different types of plant tissues. Here, we present a protoplasting-free approach, flsnRNA-seq, for large-scale full-length RNA profiling at a single-nucleus level in plants using isolated nuclei. Combined with 10x Genomics and Nanopore long-read sequencing, we validate the robustness of this approach in Arabidopsis root cells and the developing endosperm. Sequencing results demonstrate that it allows for uncovering alternative splicing and polyadenylation-related RNA isoform information at the single-cell level, which facilitates characterizing cell identities.

scholarly journals Accessible Routes Integrating Data from Multiple Sources

2020 ◽  
Vol 10 (1) ◽  
pp. 7
Author(s):  
Miguel R. Luaces ◽  
Jesús A. Fisteus ◽  
Luis Sánchez-Fernández ◽  
Mario Munoz-Organero ◽  
Jesús Balado ◽  
...  
Keyword(s):  
Information System ◽  
Data Model ◽  
Large Scale ◽  
Heterogeneous Data ◽  
Multiple Sources ◽  
Heterogeneous Data Sources ◽  
Different Types ◽  
Software Sensors ◽  
The City

Providing citizens with the ability to move around in an accessible way is a requirement for all cities today. However, modeling city infrastructures so that accessible routes can be computed is a challenge because it involves collecting information from multiple, large-scale and heterogeneous data sources. In this paper, we propose and validate the architecture of an information system that creates an accessibility data model for cities by ingesting data from different types of sources and provides an application that can be used by people with different abilities to compute accessible routes. The article describes the processes that allow building a network of pedestrian infrastructures from the OpenStreetMap information (i.e., sidewalks and pedestrian crossings), improving the network with information extracted obtained from mobile-sensed LiDAR data (i.e., ramps, steps, and pedestrian crossings), detecting obstacles using volunteered information collected from the hardware sensors of the mobile devices of the citizens (i.e., ramps and steps), and detecting accessibility problems with software sensors in social networks (i.e., Twitter). The information system is validated through its application in a case study in the city of Vigo (Spain).

scholarly journals Posture and Health: Are the Biomechanical Postural Evaluation and the Postural Evaluation Questionnaire Comparable to and Predictive of the Digitized Biometrics Examination?

2021 ◽  
Vol 18 (7) ◽  
pp. 3507
Author(s):  
Giovanni Barassi ◽  
Edoardo Di Simone ◽  
Piero Galasso ◽  
Salvatore Cristiani ◽  
Marco Supplizi ◽  
...  
Keyword(s):  
Emotional Disorders ◽  
Healthy Subjects ◽  
Large Scale ◽  
Quantitative Investigation ◽  
Evaluation Questionnaire ◽  
Evaluation Form ◽  
Margin Of Error ◽  
Different Types ◽  
Biomechanical Evaluation ◽  
Postural Tone

Background: Postural tone alterations are expressions of myofascial and, therefore, of structural, visceral, and emotional disorders. To prevent these disorders, this study proposes a quantitative investigation method which administers a postural evaluation questionnaire and a postural biomechanical evaluation to 100 healthy subjects. Methods: The reliability of the method is studied by comparing both assessments with digitized biometrics. In addition, 50 subjects undergo the biomechanical evaluation form twice, by four different operators, to study the intraoperative repeatability. Results: The results show a satisfactory overlap between the results obtained with the postural evaluation questionnaire and the postural biomechanical evaluation compared to computerized biometrics. Furthermore, intraoperative repeatability in the use of the biomechanical evaluation form is demonstrated thanks to a minimal margin of error. Conclusions: This experience suggests the importance of undertaking this path in both the curative and the preventive sphere on a large scale and on different types of people who easily, and even unknowingly, may face dysfunctional syndromes, not only structural and myofascial but also consequently of the entire body’s homeostasis.

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