Evaluation of a second order simulation for  Sterling engine design and optimisation

This paper reports on the investigation of the simulation accuracy of a second order Stirling cycle simulation tool as developed by Urieli (2001) and improvements thereof against the known performance of the GPU-3 Stirling engine. The objective of this investigation is to establish a simulation tool to perform preliminary engine design and optimisation.The second order formulation under investigation simulates the engine based on the ideal adiabatic cycle, and parasitic losses are only accounted for afterwards. This approach differs from third order formulations that simulate the engine in a coupled manner incorporating non-idealities during cyclic simulation. While the second order approach is less accurate, it holds the advantage that the degradation of the ideal performance due to the various losses is more clearly defined and offers insight into improving engine performance. It is therefore particularly suitable for preliminary design of engines.Two methods to calculate the performance and efficiency of the data obtained from the ideal adiabatic cycle and the parasitic losses were applied, namely the method used by Urieli and a proposed alternative method. These two methods differ essentially in how the regenerator and pumping losses are accounted for.The overall accuracy of the simulations, especially using the proposed alternative method to calculate the different operational variables, proved to be satisfactory. Although significant inaccuracies occurred for some of the operational variables, the simulated trends in general followed the measurements and it is concluded that this second order Stirling cycle simulation tool using the proposed alternative method to calculate the different operational variables is suitable for preliminary engine design and optimisation.

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Probabilistic Analysis of a Turbofan Secondary Flow System

Volume 4: Turbo Expo 2004 ◽

10.1115/gt2004-53197 ◽

2004 ◽

Cited By ~ 2

Author(s):

David Cloud ◽

Ethan Stearns

Keyword(s):

Secondary Flow ◽

Probabilistic Analysis ◽

Flow System ◽

Engine Performance ◽

Root Cause ◽

Engine Design ◽

Bearing Loads ◽

Input Variables ◽

Time Required ◽

Individual Input

This paper documents a probabilistic analysis of the secondary flow system in a modern commercial turbofan engine. The purpose of this analysis is to investigate the variability in the high and low rotor bearing loads and total secondary flow due to the inherent uncertainty in manufacturing processes and engine performance. In addition to quantifying the variability in bearing load and secondary flow, the sensitivity of the parameters to individual input variables is determined. The system was found to behave linearly, resulting in negligible mean shifts due to input variation. The importance of correlation among the performance parameters will be addressed, as well as the effects of different correlations. Methods used to reduce the time required for the analysis will also be discussed. This type of analysis has many applications in cost reduction, engine design, optimization, and root cause analysis that will be covered in this paper.

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Statistical analysis of second order effects variation with the stories height of reinforced concrete buildings

Revista IBRACON de Estruturas e Materiais ◽

10.1590/s1983-41952017000200005 ◽

2017 ◽

Vol 10 (2) ◽

pp. 333-357

Author(s):

D.M. OLIVEIRA ◽

N.A. SILVA ◽

C.C. RIBEIRO ◽

S.E.C. RIBEIRO

Keyword(s):

Reinforced Concrete ◽

Statistical Analysis ◽

Second Order ◽

Order Effects ◽

Reinforced Concrete Buildings ◽

First Order ◽

Concrete Buildings ◽

Ideal Situation ◽

Second Order Effects ◽

The Ideal

Abstract In this paper the simplified method to evaluate final efforts using γ z coefficient is studied considering the variation of the second order effects with the height of the buildings. With this purpose, several reinforced concrete buildings of medium height are analyzed in first and second order using ANSYS software. Initially, it was checked that the (z coefficient should be used as magnifier of first order moments to evaluate final second order moments. Therefore, the study is developed considering the relation (final second order moments/ first order moments), calculated for each story of the structures. This moments relation is called magnifier of first order moments, "γ", and, in the ideal situation, it must coincide with the γ z value. However, it is observed that the reason γ /γ z varies with the height of the buildings. Furthermore, using an statistical analysis, it was checked that γ /γ z relation is generally lower than 1.05 and varies significantly in accordance with the considered building and with the presence or not of symmetry in the structure.

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The impact of channel fin width on electrical characteristics of Si-FinFET

International Journal of Electrical and Computer Engineering (IJECE) ◽

10.11591/ijece.v12i1.pp201-207 ◽

2022 ◽

Vol 12 (1) ◽

pp. 201

Author(s):

Yousif Atalla ◽

Yasir Hashim ◽

Abdul Nasir Abd. Ghafar

Keyword(s):

Threshold Voltage ◽

Field Effect ◽

Field Effect Transistor ◽

Environmental Temperature ◽

Simulation Tool ◽

Electrical Characteristics ◽

Working Temperature ◽

Effect Transistor ◽

The Impact ◽

The Ideal

<span>This paper studies the impact of fin width of channel on temperature and electrical characteristics of fin field-effect transistor (FinFET). The simulation tool multi-gate field effect transistor (MuGFET) has been used to examine the FinFET characteristics. Transfer characteristics with various temperatures and channel fin width (W<sub>F</sub>=5, 10, 20, 40, and 80 nm) are at first simulated in this study. The results show that the increasing of environmental temperature tends to increase threshold voltage, while the subthreshold swing (SS) and drain-induced barrier lowering (DIBL) rise with rising working temperature. Also, the threshold voltage decreases with increasing channel fin width of transistor, while the SS and DIBL increase with increasing channel fin width of transistor, at minimum channel fin width, the SS is very near to the best and ideal then its value grows and going far from the ideal value with increasing channel fin width. So, according to these conditions, the minimum value as possible of fin width is the preferable one for FinFET with better electrical characteristics.</span>

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Model Based Design and Optimization for Large Bore Engines: Some Industrial Case Studies

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2017-3554 ◽

2017 ◽

Author(s):

Prashant Srinivasan ◽

Sanketh Bhat ◽

Manthram Sivasubramaniam ◽

Ravi Methekar ◽

Maruthi Devarakonda ◽

...

Keyword(s):

System Design ◽

Case Studies ◽

Control Strategy ◽

Internal Combustion Engines ◽

Cost Optimization ◽

Engine Performance ◽

Design And Optimization ◽

Model Based ◽

Performance Requirements ◽

Engine Design

Large bore reciprocating internal combustion engines are used in a wide variety of applications such as power generation, transportation, gas compression, mechanical drives, and mining. Each application has its own unique requirements that influence the engine design & control strategy. The system architecture & control strategy play a key role in meeting the requirements. Traditionally, control design has come in at a later stage of the development process, when the system design is almost frozen. Furthermore, transient performance requirements have not always been considered adequately at early design stages for large engines, thus limiting achievable controller performance. With rapid advances in engine modeling capability, it has now become possible to accurately simulate engine behavior in steady-states and transients. In this paper, we propose an integrated model-based approach to system design & control of reciprocating engines and outline ideas, processes and real-world case studies for the same. Key benefits of this approach include optimized engine performance in terms of efficiency, transient response, emissions, system and cost optimization, tools to evaluate various concepts before engine build thus leading to significant reduction in development time & cost.

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Paper 4: The Effect of Combustion Chamber Shape and Other Engine Design Factors on Exhaust Emissions

Proceedings of the Institution of Mechanical Engineers Conference Proceedings ◽

10.1243/pime_conf_1968_183_078_02 ◽

1968 ◽

Vol 183 (5) ◽

pp. 133-144 ◽

Cited By ~ 1

Author(s):

P. L. Dartnell ◽

C. L. Goodacre ◽

P. V. Lamarque

Keyword(s):

Combustion Chamber ◽

Engine Performance ◽

Exhaust System ◽

Exhaust Emissions ◽

Intake Manifold ◽

Valve Timing ◽

Mixture Formation ◽

Engine Design ◽

Basic Engine ◽

Design Factors

A Heron combustion chamber engine of 2 litre capacity has been utilized to investigate the effect of combustion chamber shape, increased mixture movement, valve timing, mixture formation, and reaction in the exhaust system on engine performance and level of exhaust emissions using the seven-mode U.S. Federal cycle. Such factors as carburettor weakening and limitation of intake manifold vacuum during overrun have been included in this investigation, and it has been shown that it is possible to reduce exhaust emissions and also satisfy the current U.S. requirements with an engine giving acceptable performance, improved economy, and unaffected reliability. Much of the information reported may be negative in terms of improvement to exhaust emissions by detailed engine design. Nevertheless, some positive conclusions have been reached as a result of this work, and it is hoped that this will draw forth more informed discussion than the authors have been able to assemble from the work attempted with one basic engine.

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On the maximum efficiency of the ideal regenerative stirling cycle

Journal of Contemporary Physics (Armenian Academy of Sciences) ◽

10.3103/s1068337210030072 ◽

2010 ◽

Vol 45 (3) ◽

pp. 137-139 ◽

Cited By ~ 2

Author(s):

R. M. Abrahamian

Keyword(s):

Maximum Efficiency ◽

Stirling Cycle ◽

The Ideal

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NFCSim: A Dynamic Fuel Burnup and Fuel Cycle Simulation Tool

Nuclear Technology ◽

10.13182/nt05-4 ◽

2005 ◽

Vol 151 (1) ◽

pp. 35-50 ◽

Cited By ~ 6

Author(s):

Erich A. Schneider ◽

Charles G. Bathke ◽

Michael R. James

Keyword(s):

Fuel Cycle ◽

Fuel Burnup ◽

Simulation Tool ◽

Cycle Simulation

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Exhaust System Gas-Dynamics in Internal Combustion Engines

ASME 2006 Internal Combustion Engine Division Spring Technical Conference (ICES2006) ◽

10.1115/ices2006-1444 ◽

2006 ◽

Cited By ~ 5

Author(s):

R. Pearson ◽

M. Bassett ◽

P. Virr ◽

S. Lever ◽

A. Early

Keyword(s):

Gas Dynamics ◽

Internal Combustion Engines ◽

Engine Performance ◽

Exhaust System ◽

Combustion Engines ◽

Cycle Simulation ◽

Model Following ◽

Analytical Tools ◽

Empirical Approaches ◽

Engine Cycle

The sensitivity of engine performance to gas-dynamic phenomena in the exhaust system has been known for around 100 years but is still relatively poorly understood. The nonlinearity of the wave-propagation behaviour renders simple empirical approaches ineffective, even in a single-cylinder engine. The adoption of analytical tools such as engine-cycle-simulation codes has enabled greater understanding of the tuning mechanisms but for multi-cylinder engines has required the development of accurate models for pipe junctions. The present work examines the propagation of pressure waves through pipe junctions using shock-tube rigs in order to validate a computational model. Following this the effects of exhaust-system gas dynamics on engine performance are discussed using the results from an engine-cycle-simulation program based on the equations of one-dimensional compressible fluid flow.

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