Axial Compressor Aerodesign Evolution at General Electric

2002 ◽  
Vol 124 (3) ◽  
pp. 321-330 ◽  
Author(s):  
Leroy H. Smith,
Keyword(s):  
State Of The Art ◽  
Axial Compressor ◽  
Prediction Method ◽  
Design System ◽  
Preliminary Design ◽  
Vector Diagram ◽  
Equilibrium Solutions ◽  
Detailed Design ◽  
The 1960S ◽  
Transonic Airfoil

This paper traces the origins of the GE Design System and how it has evolved from early methods to underlie and supplement present CFD methods, which are not themselves discussed herein. The two main elements of the detailed aero design process are vector diagram establishment and airfoil design. Their evolution is examined, and examples of how they were used to design some early GE compressors of interest are given. By the late 1950s, some transonic airfoil shapes were being custom tailored using internal blade station data from more complete radial equilibrium solutions. In the 1960s, rules for shaping transonic passages were established, and by the 1970s, custom tailoring was done for subsonic blading as well. The preliminary design layout process for a new compressor is described. It involves selecting an annulus shape and blading overall proportions that will allow a successful detailed design to follow. This requires establishment of stage loading limits that permit stall-free operation, and an efficiency potential prediction method for state-of-the-art blading. As design methods evolved, the newer approaches were calibrated with data-match experience, a process that is expected to always be needed.

State-of-the-Art Combustor Design Utilizing the Preliminary Combustor Design System PRECODES

2008 ◽  
Author(s):  
Nima Pegemanyfar ◽  
Michael Pfitzner
Keyword(s):  
Combustion Chamber ◽  
Design Process ◽  
State Of The Art ◽  
Design System ◽  
Preliminary Design ◽  
Residence Times ◽  
Design Phase ◽  
Post Processing ◽  
Design Rules ◽  
Chamber Design

Advanced state-of-the-art gas turbine combustion chamber design requires a multitude of design rules and parameters using a large number of empirical correlations. In order to allow for a more effective use of this knowledge, the preliminary combustor design system PRECODES was developed in the framework of the European research project INTELLECT D.M. (INTEgrated Lean Low Emission CombusTor Design Methodology). The development of PRECODES has already been described by the authors in previous ASME papers [1], [2]. This paper is focused on the results achieved by the application of the system and the demonstration of its potential regarding an automated combustion chamber design. Since the preliminary design of the combustor is performed and optimized fully automatically by the system, the evaluation and comparison of a much higher number of combustor configurations is possible compared to using a manual design process. Moreover detailed CFD analysis is no more limited to the final design phase, but can now be performed early during the preliminary design phase. The CFD results allow for a detailed postprocessing, to check whether all requirements, as derived from the design rules by correlations are satisfied by the configuration (e.g. zonal air/fuel ratios, residence times). The iterative combustor design process loop, as described by the authors in the previous papers [1], [2] has been closed. New, improved combustor design rules have been derived providing a sophisticated combustor design. Different preliminary combustor configurations are produced by the system on the basis of varying performance parameters and geometric requirements, resulting in a variation of the combustor volume, mixing holes sizes and application of different types of mixing holes required to meet the zonal stoichiometries. Some of the configurations have been analysed and compared more specifically using the detailed post-processing capability. An overview of this detailed post-processing analysis and of the data comparison is given in the paper. A promising configuration has been obtained with respect to NOx and CO emissions, at the same time ensuring sufficient residence times for both relight and combustion efficiency requirements.

Structural Analysis of Product and Computer-Aided Assembly Planning in AssemBL Software Package

2018 ◽  
pp. 11-33
Author(s):  
A. N. Bozhko
Keyword(s):  
Computer Aided Design ◽  
State Of The Art ◽  
Graph Model ◽  
Design System ◽  
Assembly Planning ◽  
Complex Products ◽  
Assembly Sequences ◽  
Computer Aided ◽  
Cad Cam ◽  
Aided Design

Computer-aided design of assembly processes (Computer aided assembly planning, CAAP) of complex products is an important and urgent problem of state-of-the-art information technologies. Intensive research on CAAP has been underway since the 1980s. Meanwhile, specialized design systems were created to provide synthesis of assembly plans and product decompositions into assembly units. Such systems as ASPE, RAPID, XAP / 1, FLAPS, Archimedes, PRELEIDES, HAP, etc. can be given, as an example. These experimental developments did not get widespread use in industry, since they are based on the models of products with limited adequacy and require an expert’s active involvement in preparing initial information. The design tools for the state-of-the-art full-featured CAD/CAM systems (Siemens NX, Dassault CATIA and PTC Creo Elements / Pro), which are designed to provide CAAP, mainly take into account the geometric constraints that the design imposes on design solutions. These systems often synthesize technologically incorrect assembly sequences in which known technological heuristics are violated, for example orderliness in accuracy, consistency with the system of dimension chains, etc.An AssemBL software application package has been developed for a structured analysis of products and a synthesis of assembly plans and decompositions. The AssemBL uses a hyper-graph model of a product that correctly describes coherent and sequential assembly operations and processes. In terms of the hyper-graph model, an assembly operation is described as shrinkage of edge, an assembly plan is a sequence of shrinkages that converts a hyper-graph into the point, and a decomposition of product into assembly units is a hyper-graph partition into sub-graphs.The AssemBL solves the problem of minimizing the number of direct checks for geometric solvability when assembling complex products. This task is posed as a plus-sum two-person game of bicoloured brushing of an ordered set. In the paradigm of this model, the brushing operation is to check a certain structured fragment for solvability by collision detection methods. A rational brushing strategy minimizes the number of such checks.The package is integrated into the Siemens NX 10.0 computer-aided design system. This solution allowed us to combine specialized AssemBL tools with a developed toolkit of one of the most powerful and popular integrated CAD/CAM /CAE systems.

Contemporary Methods of Designing Rail Vehicle Running Systems with the Use of CAD and CAM Solutions

2020 ◽  
Vol 64 (187) ◽  
pp. 75-80
Author(s):  
Tomasz Antkowiak ◽  
Marcin Kruś
Keyword(s):  
System Design ◽  
Preliminary Design ◽  
Support Design ◽  
Detailed Design ◽  
Final Shape ◽  
Rail Vehicle ◽  
Design Engineers ◽  
Running System ◽  
Cad Cam

The article discusses the process of designing the running system of a rail vehicle using CAD and CAM tools as the solutions supporting the process. It describes the particular stages of design taking its final shape: from a preliminary design, through a detailed design, ending with the stage of production. Each stage includes a presentation of how CAD and CAM tools are used to support design engineers in their practice. Keywords: running system, design, CAD, CAM

A Legitimacy Crisis of Representative Democracy?

2017 ◽  
Author(s):  
Jacques Thomassen ◽  
Carolien van Ham
Keyword(s):  
Empirical Evidence ◽  
State Of The Art ◽  
Short Description ◽  
The State ◽  
Political Support ◽  
Systematic Fashion ◽  
Research Questions ◽  
The 1960S ◽  
Established Democracies ◽  
Legitimacy Crisis

This chapter presents the research questions and outline of the book, providing a brief review of the state of the art of legitimacy research in established democracies, and discusses the recurring theme of crisis throughout this literature since the 1960s. It includes a discussion of the conceptualization and measurement of legitimacy, seeking to relate legitimacy to political support, and reflecting on how to evaluate empirical indicators: what symptoms indicate crisis? This chapter further explains the structure of the three main parts of the book. Part I evaluates in a systematic fashion the empirical evidence for legitimacy decline in established democracies; Part II reappraises the validity of theories of legitimacy decline; and Part II investigates what (new) explanations can account for differences in legitimacy between established democracies. The chapter concludes with a short description of the chapters included in the volume.

The Impact of Stationarity, Regularity, and Context on the Predictability of Individual Human Mobility

2021 ◽  
Vol 7 (4) ◽  
pp. 1-24
Author(s):  
Douglas Do Couto Teixeira ◽  
Aline Carneiro Viana ◽  
Jussara M. Almeida ◽  
Mrio S. Alvim
Keyword(s):  
State Of The Art ◽  
Human Mobility ◽  
Contextual Information ◽  
Prediction Method ◽  
Mobility Prediction ◽  
Mobility Patterns ◽  
Distinct Cell ◽  
Inherent Nature ◽  
The One ◽  
The Impact

Predicting mobility-related behavior is an important yet challenging task. On the one hand, factors such as one’s routine or preferences for a few favorite locations may help in predicting their mobility. On the other hand, several contextual factors, such as variations in individual preferences, weather, traffic, or even a person’s social contacts, can affect mobility patterns and make its modeling significantly more challenging. A fundamental approach to study mobility-related behavior is to assess how predictable such behavior is, deriving theoretical limits on the accuracy that a prediction model can achieve given a specific dataset. This approach focuses on the inherent nature and fundamental patterns of human behavior captured in that dataset, filtering out factors that depend on the specificities of the prediction method adopted. However, the current state-of-the-art method to estimate predictability in human mobility suffers from two major limitations: low interpretability and hardness to incorporate external factors that are known to help mobility prediction (i.e., contextual information). In this article, we revisit this state-of-the-art method, aiming at tackling these limitations. Specifically, we conduct a thorough analysis of how this widely used method works by looking into two different metrics that are easier to understand and, at the same time, capture reasonably well the effects of the original technique. We evaluate these metrics in the context of two different mobility prediction tasks, notably, next cell and next distinct cell prediction, which have different degrees of difficulty. Additionally, we propose alternative strategies to incorporate different types of contextual information into the existing technique. Our evaluation of these strategies offer quantitative measures of the impact of adding context to the predictability estimate, revealing the challenges associated with doing so in practical scenarios.

A NEW LAYOUT DESIGN SYSTEM FOR MULTICHIP MODULES

1995 ◽  
Vol 06 (03) ◽  
pp. 509-538 ◽  
Author(s):  
BERNHARD M. RIESS ◽  
ANDREAS A. SCHOENE
Keyword(s):  
Efficient Algorithm ◽  
State Of The Art ◽  
Layout Design ◽  
The State ◽  
Design System ◽  
Multichip Modules ◽  
Analytical Technique ◽  
Cut Method ◽  
First Time ◽  
Three Components

A new layout design system for multichip modules (MCMs) consisting of three components is described. It includes a k-way partitioning approach, an algorithm for pin assignment, and a placement package. For partitioning, we propose an analytical technique combined with a problem-specific multi-way ratio cut method. This method considers fixed module-level pad positions and assigns the cells to regularly arranged chips on the MCM substrate. In the subsequent pin assignment step the chip-level pads resulting from cut nets are positioned on the chip borders. Pin assignment is performed by an efficient algorithm, which profits from the cell coordinates generated by the analytical technique. Global and final placement for each chip is computed by the state-of-the-art placement tools GORDIANL and DOMINO. For the first time, results for MCM layout designs of benchmark circuits with up to 100,000 cells are presented. They show a small number of required chip-level pads, which is the most restricted resource in MCM design, and short total wire lengths.

Comparison of Piston Concept Design Solutions for Composite Cycle Engines Part II: Design Considerations

2021 ◽  
Author(s):  
Dimitrios Chatzianagnostou ◽  
Stephan Staudacher
Keyword(s):  
Gas Turbine ◽  
Design Space ◽  
Piston Compressor ◽  
Design System ◽  
Surface Load ◽  
Preliminary Design ◽  
Concept Design ◽  
Piston Engine ◽  
Engine Design ◽  
Cylinder Piston

Abstract Hecto pressure composite cycle engines with piston engines and piston compressors are potential alternatives to advanced gas turbine engines. The nondimensional groups limiting their design have been introduced and generally discussed in Part I [1]. Further discussion shows, that the ratio of effective power to piston surface characterizes the piston thermal surface load capability. The piston design and the piston cooling technology level limit its range of values. Reynolds number and the required ratio of advective to diffusive material transport limit the stroke-to-bore ratio. Torsional frequency sets a limit to crankshaft length and hence cylinder number. A rule based preliminary design system for composite cycle engines is presented. Its piston engine design part is validated against data of existing piston engines. It is used to explore the design space of piston components. The piston engine design space is limited by mechanical feasibility and the crankshaft overlap resulting in a minimum stroke-to-bore ratio. An empirical limitation on stroke-to-bore ratio is based on existing piston engine designs. It limits the design space further. Piston compressor design does not limit the piston engine design but is strongly linked to it. The preliminary design system is applied to a composite cycle engines of 22MW take-off shaft power, flying a 1000km mission. It features three 12-cylinder piston engines and three 20-cylinder piston compressors. Its specific fuel consumption and mission fuel burn are compared to an intercooled gas turbine with pressure gain combustion of similar technology readiness.

Improving a one-dimensional centrifugal compressor performance prediction method

2005 ◽  
Vol 219 (8) ◽  
pp. 653-659 ◽  
Author(s):  
E Swain
Keyword(s):  
Centrifugal Compressor ◽  
Performance Prediction ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Prediction Method ◽  
Compressor Cascade ◽  
One Dimensional ◽  
Compressor Performance ◽  
Cfd Analyses

A one-dimensional centrifugal compressor performance prediction technique that has been available for some time is updated as a result of extracting the component performance from three-dimensional computational fluid dynamic (CFD) analyses. Confidence in the CFD results is provided by comparison of overall performance for one of the compressor examples. The extracted impeller characteristic is compared with the original impeller loss model, and this indicated that some improvement was desirable. The position of least impeller loss was determined using a traditional axial compressor cascade method, and suitable algebraic expressions were derived to match the CFD data. The merit of the approach lies with the relative ease that CFD component performance currently can be achieved and adjusting one-dimensional methods to agree with the CFD-derived models.

The Design Requirement for an Unattended Engine Room Steam Propulsion Plant

1972 ◽  
Vol 9 (02) ◽  
pp. 205-215
Author(s):  
william G. Bullock ◽  
Frank D. Yonika
Keyword(s):  
Preliminary Design ◽  
Design Requirement ◽  
Detailed Design ◽  
Ship Construction ◽  
Engine Room ◽  
Base Reference ◽  
Design Requirements ◽  
Reference Document

This paper is a summary of a report prepared by the Office of Ship Construction to provide a base reference document from which a detailed design for an automated steam propulsion plant will be developed for unattended engine room operation. As the design details are developed, it may be anticipated that some of the concepts and preliminary design requirements discussed herein may be modified and/or changed to reflect these developments. It should also be noted that the concepts and opinions expressed herein are those of the authors and do not necessarily reflect those of the Maritime Administration.

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