scholarly journals A New Approach for Centrifugal Impeller Preliminary Design and Aerothermal Analysis

2018 ◽  
Vol 140 (5) ◽  
Author(s):  
Fangyuan Lou ◽  
John C. Fabian ◽  
Nicole L. Key
Keyword(s):  
Sensitivity Study ◽  
Operating Conditions ◽  
New Method ◽  
Centrifugal Impeller ◽  
Preliminary Design ◽  
New Approach ◽  
Relative Diffusion ◽  
Wide Range ◽  
Effectiveness Parameter ◽  
Selection Of

This paper introduces a new approach for the preliminary design and aerothermal analysis of centrifugal impellers using a relative diffusion effectiveness parameter. The relative diffusion effectiveness is defined as the ratio of the achieved diffusion to the maximum available diffusion in an impeller. It represents the quality of the relative diffusion process in an impeller. This parameter is used to evaluate impeller performance by correlating the relative diffusion effectiveness with the impeller isentropic efficiency using the experimental data acquired on a single-stage centrifugal compressor (SSCC). By including slip, which is appropriate considering it is an inviscid effect that should be included in the determination of maximum available diffusion in the impeller, a linear correlation between impeller efficiency and relative diffusion effectiveness resulted for all operating conditions. Additionally, a new method for impeller preliminary design was introduced using the relative diffusion effectiveness parameter, in which the optimal design is selected to maximize relative diffusion effectiveness. While traditional preliminary design methods are based on empirical loss models or empirical knowledge for selection of diffusion factor (DF) in the impeller, the new method does not require any such models, and it also provides an analytical approach for the selection of DF that gives optimal impeller performance. Validation of the method was performed using three classic impeller designs available in the open literature, and very good agreement was achieved. Furthermore, a sensitivity study shows that the method is robust in that the resulting flow angles at the impeller inlet and exit are insensitive to a wide range of blockage factors and various slip models.

scholarly journals A Proposed New Approach for the Assessment of Selected Operating Conditions of the High Voltage Cable Line

Energies ◽  
2020 ◽  
Vol 13 (20) ◽  
pp. 5275
Author(s):  
Michał Borecki
Keyword(s):  
Correction Factor ◽  
External Environment ◽  
Extreme Temperature ◽  
Operating Conditions ◽  
Positive Temperature ◽  
Cable Line ◽  
Line System ◽  
New Approach ◽  
Selection Of ◽  
Calculation Models

Calculation models for the selection of cable lines used for expansion and modernization in the energy system and energy transmission planning are recognized tools supporting decision-making in both the energy sector and energy policy. At the same time, the above calculation models contain a large number of correction factors taking into account the temperature of the external environment at various points, the mutual influence of which is not taken into account. This means limitations to today’s common approaches to solutions, especially with regard to the required safety buffer for cable line selection. To meet this challenge, this article presents a parameter that takes into account the change and difference in temperature at various points in the external environment in the analyzed cable line systems. The purpose of this paper was to develop a new approach to the selection of a cable line in order to minimize failure during operation. For this purpose, possible temperature cases that may occur during line operation in different countries and at different rated voltages have been identified. Simulation models for individual cable line layouts were developed and the extreme temperature cases of the line operation for the maximum negative and positive temperature difference between the cable core and the external environment were considered in detail. The development of the curve of the change of the correction factor for the difference in the operating temperature of the cable line will allow for a more precise selection of the cable line parameters and the shortening of the current calculation model in terms of cable selection. In addition, this article presents a comparison of the change in the value of the correction factor from the change in temperature of a selected phase of a cable line system.

Contactless Shaft Torque Detection for Wide Range Performance Measurement of Exhaust Gas Turbocharger Turbines

2013 ◽  
Vol 136 (6) ◽  
Author(s):  
Bernhardt Lüddecke ◽  
Dietmar Filsinger ◽  
Jan Ehrhard ◽  
Bastian Steinacher ◽  
Christian Seene ◽  
...  
Keyword(s):  
Internal Combustion Engine ◽  
Combustion Engine ◽  
Internal Combustion ◽  
Sensitivity Study ◽  
Operating Conditions ◽  
Measuring System ◽  
Sensor Calibration ◽  
Torque Measurement ◽  
Wide Range ◽  
Shaft Torque

Turbochargers develop away from an auxiliary component—being “off the shelve”—towards an integrated component of the internal combustion engine. Hence, increased attention is paid to the accuracy of the measured turbine and compressor maps. Especially turbine efficiency measurement under engine-relevant operating conditions (pulsed flow) is recently receiving increased attention in the respective research community. Despite various turbine map extrapolation methods, sufficient accuracy of the input test data is indispensable. Accurate experimental data are necessary to achieve high quality extrapolation results, enabling a wide range and precise prediction of turbine behavior under unsteady flow conditions, determined by intermittent operation of the internal combustion engine. The present work describes the first application of a contactless shaft torque measurement technique—based on magnetostriction—to a small automotive turbocharger. The contactless torque measuring system is presented in detail and sensor principle as well as sensor calibration are illustrated. A sensitivity study regarding sensor position influences onto sensor signal proves the robustness and very good repeatability of the system. In the second part of the paper, steady state experimental results from operation on a conventional hot gas test stand over a wide map range are presented. These results are validated against full turbine stage (adiabatic as well as diabatic) CFD results as well as against “cold” efficiency measurements, based on measured inlet and outlet temperatures. The influence and relevance of bearing friction for such measurements is underlined and the improvements on this matter—achieved by direct torque measurement—are demonstrated.

scholarly journals Using depolarization to quantify ice nucleating particle concentrations: a new method

2017 ◽  
Vol 10 (12) ◽  
pp. 4639-4657 ◽  
Author(s):  
Jake Zenker ◽  
Kristen N. Collier ◽  
Guanglang Xu ◽  
Ping Yang ◽  
Ezra J. T. Levin ◽  
...  
Keyword(s):  
Standard Procedure ◽  
Diffusion Chamber ◽  
Operating Conditions ◽  
Ice Crystals ◽  
New Method ◽  
State University ◽  
Analysis Method ◽  
Colorado State University ◽  
Nominal Size ◽  
Wide Range

Abstract. We have developed a new method to determine ice nucleating particle (INP) concentrations observed by the Texas A&M University continuous flow diffusion chamber (CFDC) under a wide range of operating conditions. In this study, we evaluate differences in particle optical properties detected by the Cloud and Aerosol Spectrometer with POLarization (CASPOL) to differentiate between ice crystals, droplets, and aerosols. The depolarization signal from the CASPOL instrument is used to determine the occurrence of water droplet breakthrough (WDBT) conditions in the CFDC. The standard procedure for determining INP concentration is to count all particles that have grown beyond a nominal size cutoff as ice crystals. During WDBT this procedure overestimates INP concentration, because large droplets are miscounted as ice crystals. Here we design a new analysis method based on depolarization ratio that can extend the range of operating conditions of the CFDC. The method agrees reasonably well with the traditional method under non-WDBT conditions with a mean percent error of ±32.1 %. Additionally, a comparison with the Colorado State University CFDC shows that the new analysis method can be used reliably during WDBT conditions.

Upgrading of the STP Uithoorn: treatment of nutrient rich wastewater from horticulture

2005 ◽  
Vol 52 (4) ◽  
pp. 81-90 ◽  
Author(s):  
P. Piekema ◽  
R. Neef
Keyword(s):  
Primary Treatment ◽  
Preliminary Design ◽  
Operational Control ◽  
Tertiary Treatment ◽  
Wide Range ◽  
High Loading Rate ◽  
Stage System ◽  
Nutrient Discharge ◽  
Selection Of ◽  
System Choice

The STP Uithoorn will be upgraded to accommodate the treatment of wastewater from a growing population and to meet more stringent nutrient discharge limits in 2006. In 2003 a system choice and preliminary design was made for the upgrading. A special feature is the nutrient rich wastewater flow from the rapidly developing horticulture in the area. Since the future loads from horticulture are highly uncertain, flexibility of the STP after upgrading is an important issue. A three stage system was selected: improved physical-chemical primary treatment, secondary treatment by activated sludge, and tertiary treatment by denitrifying filters. In this way an important part of the existing infrastructure can be reused, and flexibility is assured by constructing the tertiary treatment in modules and by providing a wide range of operational control possibilities. In this paper the process of system choice and selection of type of tertiary treatment are described, as well as the optimisation of the existing treatment. In order to determine the feasibility of allowing a high loading rate on the existing secondary clarifiers, a two-dimensional hydraulic model of the clarification process was used.

scholarly journals Heavy Duty Gas Turbine Simulation: A Compressor IGV Airfoil Off-Design Characterization

2010 ◽  
Author(s):  
Carlo Carcasci ◽  
Riccardo Da Soghe ◽  
Andrea Silingardi ◽  
Pio Astrua ◽  
Stefano Traverso
Keyword(s):  
Operating Conditions ◽  
Cfd Analysis ◽  
Plant Behavior ◽  
Wide Range ◽  
Loss Coefficients ◽  
Heavy Duty Gas Turbine ◽  
Set Up ◽  
System Configurations ◽  
Profile Loss ◽  
Selection Of

The correct simulation of power plant behavior over a variety of operating conditions has to be extremely detailed in order to provide reliable help to the turbomachinery developers. The latter instance implies for designers and commercial personnel to be equipped with reliable calculation tools (in-house developed or commercial). In particular, Performance Analysis Codes (PACs) allow the designers to analyze different system configurations. To predict off-design behavior, these codes need to be not limited to thermodynamic analysis, but also able to perform a simplified description of each component that require a specific set of correlations. The selection of suitable correlation sets for compressor IGV airfoils could be very difficult. This paper deal with a procedure based on 2D-CFD analysis to provide a reliable evaluation of compressor IGV airfoils deviation and profile loss coefficients in a wide range of operating condition. The analysis were set up on the IGV of the Ansaldo Energia AE94.3A compressor and the developed correlations were successfully implemented in an in-house PAC called ESMS.

scholarly journals On the Selection of Optimal Propeller Diameter for a 120m Cargo Vessel

2018 ◽  
Author(s):  
Jennie Andersson ◽  
Robert Gustafsson ◽  
Arash Eslamdoost ◽  
Rickard E. Bensow
Keyword(s):  
Open Water ◽  
Operating Conditions ◽  
Series Data ◽  
Preliminary Design ◽  
Optimum Diameter ◽  
Viscous Losses ◽  
Computational Fluid Dynamics Cfd ◽  
Propulsion Unit ◽  
Hydrodynamic Effects ◽  
Selection Of

In the preliminary design of a propulsion unit the selection of propeller diameter is most commonly based on open water tests of systematic propeller series. The optimum diameter obtained from the propeller series data is however not considered to be representative for the operating conditions behind the ship, instead a slightly smaller diameter is often selected. We have used computational fluid dynamics (CFD) to study a 120m cargo vessel with an integrated rudder bulb-propeller hubcap system and a 4-bladed propeller series, to increase our understanding of the hydrodynamic effects influencing the optimum. The results indicate that a 3-4 % smaller diameter is optimal in behind conditions in relation to open water conditions at the same scale factor. The reason is that smaller, higher loaded propellers perform better together with a rudder system. This requires that the gain in transverse kinetic energy losses thanks to the rudder overcomes the increase in viscous losses in the complete propulsion system.

Modeling Biomass Gasification: A New Approach to Utilize Renewable Sources of Energy

2008 ◽  
Author(s):  
M. Vaezi ◽  
M. Passandideh-Fard ◽  
M. Moghiman ◽  
M. Charmchi
Keyword(s):  
Selection Procedure ◽  
Calorific Value ◽  
Gas Temperature ◽  
New Approach ◽  
Wide Range ◽  
Specific Biomass ◽  
Thermochemical Equilibrium ◽  
Biomass Materials ◽  
Gasification Efficiency ◽  
Selection Of

Thermochemical equilibrium modeling is the basis of the numerical method implemented in this study to predict the performance of a biomass gasifier. To validate the model, a close agreement is shown between numerical and experimental results. The model is then used in order to optimize the selection procedure of a specific biomass for a certain application. For this purpose, the minimum and maximum amount of carbon, hydrogen, and oxygen for 55 different biomass materials are extracted to calculate the range of variation of oxygen content and carbon/hydrogen ratio. The influences of such variations on syngas characteristics are then studied. Syngas characteristics are comprised of syngas calorific value, outlet gas temperature, gasification efficiency, and the volume of syngas obtained. The results are plotted in a generalized format that may be used for a wide range of biomass materials. These plots can be used for the selection of a biomass material based on desired conditions. Therefore, the developed model in this study provides a tool for design optimization of a biomass downdraft gasifier.

Design charts for the selection of acoustical enclosures for diesel engine generator sets

2003 ◽  
Vol 217 (3) ◽  
pp. 329-336 ◽  
Author(s):  
T. A. Osman
Keyword(s):  
Diesel Engine ◽  
Insertion Loss ◽  
Design Stage ◽  
Preliminary Design ◽  
Generating Sets ◽  
Design Charts ◽  
Wide Range ◽  
Preliminary Design Stage ◽  
Generator Sets ◽  
Selection Of

It has been realized that attenuation of the noise radiated from diesel engine generating sets is a challenge for the designer. The enclosure, which may be designed for noise reduction, has to allow for the flow of the necessary amount of air. The present work is an attempt to tackle such a contradictory problem. A mathematical model is developed to predict the enclosure design configuration. The parameters affecting the insertion loss, such as enclosure and silencer dimensions, number of baffles, and sound absorption material specifications are taken into account. To verify the developed model, experimental measurements based on ISO 8528 part 10 are conducted. Four different generating sets covering a wide range of power rating are employed. The effect of changing each parameter on the insertion loss is studied separately for the chosen range. Design charts, based on the results of the present investigation, are constructed to facilitate the section of a proper acoustical enclosure configuration at the preliminary design stage.

Performance Prediction of Centrifugal Impellers Using a Two-Zone Model

2008 ◽  
Author(s):  
Ian Britton ◽  
J. E. Donald Gauthier
Keyword(s):  
Performance Prediction ◽  
Pressure Ratio ◽  
Model Development ◽  
Computer Code ◽  
Centrifugal Impeller ◽  
Zone Model ◽  
Preliminary Design ◽  
Wide Range ◽  
Mass Flow Rates ◽  
Isentropic Efficiency

This paper outlines the methodology and theory required for the development of a computer code for the performance prediction of centrifugal impellers. The theory is blended from two main sources on two-zone model development. The equations provided show a simplified version of previous two-zone models published while maintaining a similar level of accuracy in the prediction of pressure ratio and isentropic efficiency. The idea behind the development of the algorithm is the production of an impeller map which can be used in the preliminary design phase with a minimum amount of input information, namely basic geometry which could be determined from simple design point calculations. Validation of the model was performed against compressor maps and geometries available in the literature. It was subsequently shown that with the blending of inlet, diffusion ratio and two-zone models, a centrifugal impeller model was constructed which agreed well over a wide range of rotational speeds and mass flow rates.

Statistical Sensitivity Study of Frequency Mistuning on the Prediction of the Flutter Boundary in a Transonic Fan

2016 ◽  
Author(s):  
Atsushi Tateishi ◽  
Toshinori Watanabe ◽  
Takehiro Himeno ◽  
Mizuho Aotsuka ◽  
Takeshi Murooka
Keyword(s):  
Aerodynamic Force ◽  
Sensitivity Study ◽  
Dominant Mode ◽  
Operating Conditions ◽  
Modal Properties ◽  
Numerical Predictions ◽  
Wide Range ◽  
Damping Rate ◽  
Flutter Boundary ◽  
Transonic Fan

This paper aims at quantifying the stabilization effect of mistuning in transonic fan flutter. The results are used to support the evaluation of flutter boundary and to clarify the reason for the mismatch observed in the numerical predictions reported in our previous study. Mistuning is modeled by the deviation of blade-mode frequency, and the stability analysis of vibrating blades is formulated as an eigenproblem of the equation of motion including self-excited aerodynamic force obtained by fluid-structure interaction simulations. Statistics about the modal properties are obtained by Monte Carlo simulation. The change in the averaged damping rate and flutter boundary is evaluated in a wide range of mistuning levels and operating conditions. Nominal levels of mistuning due to manufacturing tolerance have little effect to the flutter boundary because the decline in aerodynamic damping is very steep. Therefore, the accuracy associated with the computational fluid dynamics is likely to have caused the mismatch in the flutter boundary. Histograms of modal properties show that the inter-blade phase angle and blade amplitudes in flutter mode can be highly scattered, even if the level of mistuning is nominal. For largely mistuned cases, new crests which do not exist in nominal cases appear in the eigenvalue histogram. They were found to be highly-localized, single-blade dominant mode.

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