A New Analytical Model of a Centrifugal Compressor and Validation by Experiments

2010 ◽  
Vol 26 (1) ◽  
pp. 37-45 ◽  
Author(s):  
H. Pourfarzaneh ◽  
A. Hajilouy-Benisi ◽  
M. Farshchi
Keyword(s):  
Conceptual Design ◽  
Centrifugal Compressor ◽  
Experimental Studies ◽  
Design Tool ◽  
Operating Conditions ◽  
Experimental Results ◽  
Design Phase ◽  
Robust Model ◽  
Conceptual Design Phase ◽  
Wide Range

AbstractIn the conceptual design phase of a turbocharger, where emphasis is mainly on parametric studies, before manufacturing and tests, a generalized and robust model that implies over a wide range properly, is unavoidable. The critical inputs such as compressor maps are not available during the conceptual design phase. Hence, generalized compressor models use alternate methods that work without any supplementary tests and can operate on wide range. One of the common and applicable modeling methods in design process is the ‘Dimensionless Modeling’ using the constant coefficient scaling (CCS). This method almost can predict the compressor characteristics at design point. However, at off design conditions, error goes up as mass flow and speed parameters increase. Therefore, the results are not reliable at these points. In this paper, a variable coefficient scaling (VCS) method is described. Then, a centrifugal compressor is modeled using the VCS method. To evaluate the model and compare it with the experimental results, some supplementary experiments are performed. Experimental studies are carried out on the compressor of a S2B model of the Schwitzer turbocharger in the turbocharger Lab., at Sharif University of Technology. The comparison between the experimental results and those obtained by the VCS method indicates a good agreement. It also suggests that the present model can be used as an effective design tool for all operating conditions.

Elastohydrodynamic Film Thickness in Concentrated Contacts: Part 2: Correlation of Experimental Results with Elastohydrodynamic Theory

1986 ◽  
Vol 200 (3) ◽  
pp. 219-226 ◽  
Author(s):  
R J Chittenden ◽  
D Dowson ◽  
C M Taylor
Keyword(s):  
Film Thickness ◽  
Experimental Studies ◽  
Elastohydrodynamic Lubrication ◽  
Operating Conditions ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Dimensionless Parameters ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Computational Procedures

The existence of a coherent film of lubricant between highly loaded machine elements has been recognized for many years. Over this period of time measurements of film thickness have gone hand in hand with theoretical analyses in the field now known as elastohydrodynamic lubrication. The experimental techniques of capacitance, electrical resistance and X-ray measurement have been supplemented by the use of optical interferometry while the analytical expressions obtained with the use of elegant simplifications have been superseded by those developed from extensive and comprehensive computational procedures. These developments in experimental techniques have yielded a substantial number of measurements of both minimum and central film thickness. Likewise, the advent of the digital computer has allowed the derivation of a large number of solutions to the problem of elastohydrodynamic lubrication of concentrated contacts. All these results, covering a wide range of geometrical conditions, are to be found in the literature, yet little attempt appears to have been made to assemble a representative set of experimental data to permit a detailed evaluation of the theoretical formulae for elliptical contacts. The second part of this paper therefore considers the correlation between a number of experimental studies covering a wide range of operating conditions and geometries, and the predictions of recent elastohydrodynamic theory. Some of the important aspects of each set of experimental results are then considered and examples are provided which illustrate the following points: 1. Good estimates of lubricant film thickness may be obtained from the theoretical expressions recently derived, even when the dimensionless parameters involved are outside the ranges considered in the derivation of the formulae. 2. The discrepancies which exist between theoretical predictions and some of the measured film thicknesses are nevertheless quite large, even when the dimensionless parameters are within their usual limits. On the whole there is good agreement between experiment and theory, while the general trend of the results indicates that theoretical predictions may underestimate the minimum film thickness by about 10 per cent and the central film thickness by about 25 per cent. This measure of agreement is quite remarkable when the extreme difficulty of interpreting the magnitudes of effective and very thin mean film thicknesses between machined components in various forms of experimental equipment is considered.

Conceptual Design of a Positively Engaged Continuously Variable Transmission

2008 ◽  
Author(s):  
Ryan R. Dalling ◽  
B. Levi Haupt ◽  
Robert H. Todd
Keyword(s):  
Product Development ◽  
Conceptual Design ◽  
Continuously Variable Transmission ◽  
Operating Conditions ◽  
Product Development Process ◽  
Design Phase ◽  
Concept Generation ◽  
Conceptual Design Phase ◽  
Concept Evaluation ◽  
Variable Transmission

Previous research and publications at Brigham Young University have established the new positive engagement continuously variable transmission (PECVT) family of continuously variable transmissions (CVTs). Various embodiments of PECVTs have been identified and surveyed; resulting in the identification of the behavior termed the non-integer tooth problem. Additional research has been conducted to further explore the non-integer tooth problem and identify a feasible solution to the problem through the use of a product development method. This publication will address the conceptual design phase of the product development process for a PECVT. This will include: the identification of the operating conditions of a PECVT, i.e. further detail of the non-integer tooth problem, identification of required characteristics for a solution, design specifications, concept generation, concept evaluation, and concept selection. The conceptual design phase will result in a conceptual solution which will satisfy the identified characteristic requirement and designs specifications.

Accuracy of Analytical Engine Weight Estimation During the Conceptual Design Phase

2010 ◽  
Author(s):  
Fabian Donus ◽  
Reinhold Schaber ◽  
Klaus-Juergen Schmidt ◽  
Stephan Staudacher
Keyword(s):  
Conceptual Design ◽  
Estimation Method ◽  
Design Tool ◽  
Parameter Study ◽  
Test Case ◽  
Design Phase ◽  
Weight Estimation ◽  
Geometric Models ◽  
Conceptual Design Phase ◽  
Engine Design

This paper addresses the quality of weight estimation that can be achieved in the early design phase and illustrates the significance of the results for conceptual engine design. A study was undertaken to determine the accuracy of weight estimation during the conceptual design phase. To this end, different engines were modeled using the preliminary design tool MOPEDS. The estimation method used to generate the results is based on geometric models for the considered component parts that have been calibrated as closely as possible to the existing geometries. Furthermore, the modeled part weights provided by MOPEDS have been compared to the real part weights to assess the uncertainty of the estimation method. The deviations are discussed to identify where an improvement of the method could be profitable with regard to a better overall estimation. It has been shown that for some hardware the estimation method is already very accurate, whereas some parts have geometric models that require improvement to realize an overall high quality. One of the calibrated engine models was used additionally as the basis for a parameter study to determine the accuracy of the part weight estimation method using MOPEDS in automatic design mode. The results showed that the deviation in the overall component mass for each test case was nearly constant during this study.

scholarly journals Application of Noise Certification Regulations within Conceptual Aircraft Design

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 210
Author(s):  
Michel Nöding ◽  
Lothar Bertsch
Keyword(s):  
Conceptual Design ◽  
Aircraft Design ◽  
Low Noise ◽  
Operating Conditions ◽  
Published Data ◽  
Design Phase ◽  
Simulation Process ◽  
Research Activities ◽  
Conceptual Design Phase ◽  
Conceptual Aircraft Design

ICAO Annex 16 regulations are used to certify the acoustic performance of subsonic transport aircraft. Each aircraft is classified according to the measured EPNL levels at specific certification locations along the approach and departure. By simulating this certification process, it becomes possible to identify all relevant parameters and assess promising measures to reduce the noise certification levels in compliance with the underlying ICAO regulations, i.e., allowable operating conditions of the aircraft. Furthermore, simulation is the only way to enable an assessment of novel technology and non-existing vehicle concepts, which is the main motivation behind the presented research activities. Consequently, the ICAO Annex 16 regulations are integrated into an existing noise simulation framework at DLR, and the virtual noise certification of novel aircraft concepts is realized at the conceptual design phase. The predicted certification levels can be directly selected as design objectives in order to realize an advantageous ICAO noise category for a new aircraft design, i.e., simultaneously accounting for the design and the resulting flight performance. A detailed assessment and identification of operational limits and allowable flight procedures for each conceptual aircraft design under consideration is enabled. Sensitivity studies can be performed for the relevant input parameters that influence the predicted noise certification levels. Specific noise sources with a dominating impact on the certification noise levels can be identified, and promising additional low-noise measures can be applied within the conceptual design phase. The overall simulation process is applied to existing vehicles in order to assess the validity of the simulation resultsfcompared to published data. Thereafter, the process is applied to some DLR low-noise aircraft concepts to evaluate their noise certification levels. These results can then be compared to other standard noise metrics that are typically applied in order to describe aircraft noise, e.g., SEL isocontour areas. It can be demonstrated that certain technologies can significantly reduce the noise impact along most of an approach or departure flight track but have only a limited influence on the noise certification levels and vice versa. Finally, an outlook of the ongoing developments is provided, in order to apply the new simulation process to supersonic aircraft. Newly proposed regulations for such concepts are implemented into the process in order to evaluate these new regulations and enable direct comparison with existing regulations.

Laminar Flamelet Based NOx Predictions for Gas Turbine Combustors

2014 ◽  
Author(s):  
Mohan Sripathi ◽  
Sundar Krishnaswami ◽  
Allen M. Danis ◽  
Shih-Yang Hsieh
Keyword(s):  
Flame Front ◽  
Gas Turbine ◽  
Design Tool ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Design Phase ◽  
Species Transport ◽  
Gas Turbine Combustors ◽  
Low Emission ◽  
Wide Range

Stringent emissions regulations have led engine manufacturers to focus on fuel-efficient low emission technologies. Basic understanding and modeling of fundamental mechanisms governing formation and destruction of NOx, CO and UHC is essential to reduce pollutant emissions. Recent advances in turbulent combustion modeling have enabled designers to use CFD as a design tool for evaluating low emission concepts at the conceptual design phase. Prediction of pollutant NOx for gas turbine combustors has proven successful for design validation applications. The challenge is to provide quick and accurate estimates of NOx for application to gas turbine combustor preliminary design phase, which can be characterized by multiple design changes, varying operating conditions and a variety of fuel staging concepts. NOx formation processes are typically slow compared to the fast hydrocarbon oxidation reactions. As a result, NOx predictions are typically performed as a post-processing step on thermal field obtained from reacting flow simulations. This work builds on prior work on flamelet approach [1,3] by suitably blending it with FLUENT®’s species transport. NOx production within gas turbine combustors has contributions from two major sources: flame front & post-flame thermal NO. The flame front contributions are obtained from flamelet based computations involving detailed chemistry whereas the slow evolution of post-flame NOx is tracked by explicitly solving for NO species transport. The closure of turbulence-chemistry-interactions is derived from Girimaji’s [2] assumed PDF closure using temperature-composition correlations. A Gaussian PDF shape is used with mean and variance of temperatures accounting for the first and second moments, required for PDF weighting computations. The formulation has been validated against SANDIA D flame, and then extended to GE Aviation’s fielded combustors over a wide range of operating conditions, with errors within 11% at Take-Off condition. The model has also been used for pre-test predictions on a number of combustors under development.

Applying Function-Based Failure Propagation in Conceptual Design

2007 ◽  
Author(s):  
Daniel Krus ◽  
Katie Grantham Lough
Keyword(s):  
Risk Analysis ◽  
Product Design ◽  
Conceptual Design ◽  
Functional Model ◽  
Thermal Control ◽  
Design Phase ◽  
Historical Knowledge ◽  
Conceptual Design Phase ◽  
Failure Propagation ◽  
Potential Risks

When designing a product, the earlier the potential risks can be identified, the more costs can be saved, as it is easier to modify a design in its early stages. Several methods exist to analyze the risk in a system, but all require a mature design. However, by applying the concept of “common interfaces” to a functional model and utilizing a historical knowledge base, it is possible to analyze chains of failures during the conceptual phase of product design. This paper presents a method based on these “common interfaces” to be used in conjunction with other methods such as Risk in Early Design in order to allow a more complete risk analysis during the conceptual design phase. Finally, application of this method is demonstrated in a design setting by applying it to a thermal control subsystem.

Experimental Studies on Cooling Effectiveness of the Double-Decker Air Jet Impingement With Film Outflow

2007 ◽  
Author(s):  
Junkui Mao ◽  
Wen Guo ◽  
Zhenxiong Liu ◽  
Jun Zeng
Keyword(s):  
Infrared Radiation ◽  
Experimental Studies ◽  
Jet Impingement ◽  
Experimental Results ◽  
Thermal Camera ◽  
Local Cooling ◽  
Cooling Effectiveness ◽  
Air Jet ◽  
Double Decker ◽  
Wide Range

Experiments were carried out to investigate the cooling effectiveness of a lamellar double-decker impingement/effusion structure. Infrared radiation (I.R.) thermal camera was used to measure the temperature on the outside surface of the lamellar double-decker. Experimental results were obtained for a wide range of governing parameters (blowing rate M (0.0017∼0.0066), the ratio of the jet impingement distance to the diameter of film hole H/D (0.5∼1.25), the ratio of the distance between the jet hole and film hole to the diameter of the film hole P/D (0, 3, 4), and the material of double-decker (Steel and Copper)). It was observed that the local cooling effectiveness η varies with all these parameters in a complicated way. All the results show that higher cooling effectiveness η is achieved in larger blowing rate cases. A certain range of H/D and P/D can be designed to result in the maximum cooling effectiveness η. And η is less sensitive to the material type compared with those parameters such as H/D, M and P/D.

Variantenreiche Fabrikplanung*/Variant-based factory planning - Automatically generated simulation models to support factory engineering

2017 ◽  
Vol 107 (09) ◽  
pp. 640-646
Author(s):  
J. Jaensch ◽  
A. Neyrinck ◽  
A. Lechler ◽  
A. Prof. Verl
Keyword(s):  
Energy Efficiency ◽  
Conceptual Design ◽  
Simulation Models ◽  
Design Phase ◽  
Factory Planning ◽  
Cycle Times ◽  
Automated Generation ◽  
Conceptual Design Phase

Maschinen und besonders Anlagen werden meist in individuellen Prozessen entwickelt. Bereits in der Angebots- und Konzeptionsphase werden im direkten Austausch mit dem Auftraggeber unterschiedliche Varianten diskutiert und iteriert. Zur Bewertung der Varianten sind neben den Anschaffungskosten unter anderem laufzeitabhängige Größen wie Taktzeiten und Energieeffizienz zu untersuchen. Der Beitrag stellt einen Ansatz zur simulationsbasierten Untersuchung für die automatisierte Variantengenerierung von Anlagen vor.   The development of machines or plants is a very individual process. Within the conceptual design phase, many different variants have to be discussed with customers and adapted to their needs. For a decent evaluation of the different variants, many parameters beyond static values such as costs are important. Term-dependent values like cycle times and energy efficiency also have to be investigated. This paper presents a method for the automated generation of plant variants based on simulation.

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