Gain and loss mechanisms for neutral species in low pressure fluorocarbon plasmas by infrared spectroscopy

2012 ◽  
Vol 30 (5) ◽  
pp. 051308 ◽  
Author(s):  
Caleb T. Nelson ◽  
Lawrence J. Overzet ◽  
Matthew J. Goeckner
Keyword(s):  
Infrared Spectroscopy ◽  
Low Pressure ◽  
Neutral Species ◽  
Fluorocarbon Plasmas ◽  
Gain And Loss ◽  
Loss Mechanisms

scholarly journals The Role of Reverse Transcriptase in Intron Gain and Loss Mechanisms

2011 ◽  
Vol 29 (1) ◽  
pp. 179-186 ◽  
Author(s):  
Noa E. Cohen ◽  
Roy Shen ◽  
Liran Carmel
Keyword(s):  
Reverse Transcriptase ◽  
Intron Gain ◽  
Gain And Loss ◽  
Loss Mechanisms

Steady and unsteady numerical investigation of flow interaction between low-pressure turbine blade, intermediate turbine duct and power turbine vane

2018 ◽  
Vol 232 (23) ◽  
pp. 4312-4331
Author(s):  
Jie Gao ◽  
Xuezheng Liu ◽  
Xudong Zhao ◽  
Weiliang Fu ◽  
Guoqiang Yue ◽  
...  
Keyword(s):  
Turbine Blade ◽  
Low Pressure ◽  
Secondary Flows ◽  
Fast Fourier Transformation ◽  
Intermediate Turbine Duct ◽  
Low Pressure Turbine ◽  
Flow Interaction ◽  
Power Turbine ◽  
Turbine Vane ◽  
Loss Mechanisms

Flows in an intermediate turbine duct connecting low-pressure turbines and power turbines are very complex, affected by the upstream low-pressure turbine flow structures. Non-uniformities originating from the duct with struts also affect the power turbine inflow conditions, resulting in reduced efficiency. The present investigation is done to clarify the flow and loss mechanisms within the intermediate turbine duct and the power turbine. Steady and unsteady numerical investigations of the flow interaction between low-pressure turbine blade, intermediate turbine duct and power turbine vane were conducted. Effects of upstream low-pressure turbine blade on intermediate turbine duct flow fields and loss characteristics, and that of intermediate turbine duct with big and small struts on power turbine aerodynamics are explored. The generation and propagation of wake and secondary flows through the whole configuration are described. The fast Fourier transformation analyses of the flow in the low-pressure turbine blade, intermediate turbine duct and power turbine vane are also presented. Results from the steady and unsteady investigations show complex flow patterns resulted from blade–strut–vane flow interactions, which are not obtainable from intermediate turbine duct-only or power turbine-only simulations. The intermediate turbine duct has a great amplifying influence on the distorted inflow, and the inlet flow with upstream wakes and secondary flows introduces a high-loss area along the casing at intermediate turbine duct exit. Detailed results are presented and discussed for the flow physics and loss mechanisms as well as the unsteady flow evolution through the low-pressure turbine blade, intermediate turbine duct and power turbine vane.

A Methodology for a Detailed Loss Prediction in Low Pressure Steam Turbines

2017 ◽  
Author(s):  
Marius Grübel ◽  
Robin M. Dovik ◽  
Markus Schatz ◽  
Damian M. Vogt
Keyword(s):  
Boundary Layer ◽  
Evaluation Method ◽  
Three Dimensional ◽  
Low Pressure ◽  
Steam Turbines ◽  
Cfd Simulations ◽  
Depth Analysis ◽  
Pressure Steam ◽  
The Impact ◽  
Loss Mechanisms

An evaluation method for CFD simulations is presented, which allows an in-depth analysis of different loss mechanisms applying the approach of entropy creation proposed by Denton. The entropy creation within each single mesh element is determined based on the entropy flux through the cell faces and therefore the locations, where losses occur, can be identified clearly. By using unique features of the different loss mechanisms present in low pressure steam turbines, the losses are categorized into boundary layer, wake mixing and shock losses as well as thermodynamic wetness losses. The suitability of the evaluation method is demonstrated by means of steady state CFD simulations of the flow through a generic last stage of a low pressure steam turbine. The simulations have been performed on streamtubes extracted from three-dimensional simulations representing the flow at 10 % span. The impact of non-equilibrium steam effects on the overall loss composition of the stator passage is investigated by comparing the results to an equilibrium steam simulation. It is shown, that the boundary layer losses for the investigated case are of similar magnitude, but the shock and wake losses exhibit significant differences.

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