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    Investigation on effect of centrifugal compressor volute cross-section shape on performance and flow field

    , Article Proceedings of the ASME Turbo Expo ; Volume 8, Issue PARTS A, B, AND C , 2012 , Pages 871-880 ; 9780791844748 (ISBN) Mojaddam, M ; Benisi, A. H ; Movahhedy, M. R ; Sharif University of Technology
    2012
    Abstract
    In this article, the effects of volute cross section shape and centroid profile of a centrifugal compressor volute were investigated. The performance characteristics of a turbocharger compressor were obtained experimentally by measuring rotor speed and flow parameters at the inlet and outlet of the centrifugal compressor. The three dimensional flow field model of the compressor was obtained numerically solving Navier- Stokes equations with SST turbulence model. The compressor characteristic curves were plotted. For model verification, the results were compared with experimental data, showing good agreement. Modification of a volute was performed by introducing a shape factor for volute cross... 

    Optimization of electrical power in multistage centrifugal compressors

    , Article 2011 IEEE International Conference on Control System, Computing and Engineering, ICCSCE 2011, Penang, 25 November 2011 through 27 November 2011 ; 2011 , Pages 193-197 ; 9781457716423 (ISBN) Mohammadi, H ; Kermani, M ; Sharif University of Technology
    Abstract
    Over the time, multistaging has proved to have some great benefits such as less electrical usage, so, nowadays; optimization of the electrical power usage in centrifugal compressors is an important issue to lead to the least usage of power. In this paper, we present a novel algorithm that provides this desire; it also shows different arrangement of the stages for the considered compressor. Simple single-stage compressor pressure ratio is normally limited by constraints of both aerodynamic and structural types. Reaching to minimum power leads to the least usage of electrical power. In this paper, we utilize theoretical relations which are extracted and have been presented a novel numerical... 

    Inertial particle focusing in serpentine channels on a centrifugal platform

    , Article Physics of Fluids ; Volume 30, Issue 1 , 2018 ; 10706631 (ISSN) Shamloo, A ; Mashhadian, A ; Sharif University of Technology
    American Institute of Physics Inc  2018
    Abstract
    Inertial particle focusing as a powerful passive method is widely used in diagnostic test devices. It is common to use a curved channel in this approach to achieve particle focusing through balancing of the secondary flow drag force and the inertial lift force. Here, we present a focusing device on a disk based on the interaction of secondary flow drag force, inertial lift force, and centrifugal forces to focus particles. By choosing a channel whose cross section has a low aspect ratio, the mixing effect of the secondary flow becomes negligible. To calculate inertial lift force, which is exerted on the particle from the fluid, the interaction between the fluid and particle is investigated... 

    Investigation of a centrifugal compressor and study of the area ratio and TIP clearance effects on performance

    , Article Journal of Thermal Science ; Volume 17, Issue 4 , December , 2008 , Pages 314-323 ; 10032169 (ISSN) Nili Ahmadabadi, M ; Hajilouy Benisi, A ; Durali, M ; Ghadak, F ; Sharif University of Technology
    2008
    Abstract
    In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was... 

    Experimental & numerical investigation of a centrifugal compressor and numerical study of the area ratio and tip clearance effects on the performance characteristic

    , Article 2008 ASME Turbo Expo, Berlin, 9 June 2008 through 13 June 2008 ; Volume 6, Issue PART B , 2008 ; 9780791843161 (ISBN) Nili Ahmadabadi, M ; Hajilouy Benisi, A ; Durali, M ; Motavalli, S. M ; Sharif University of Technology
    American Society of Mechanical Engineers(ASME)  2008
    Abstract
    In this research, the centrifugal compressor of a turbocharger is investigated experimentally and numerically. Performance characteristics of the compressor were obtained experimentally by measurements of rotor speed and flow parameters at the inlet and outlet of the compressor. Three dimensional flow field in the impeller and diffuser was analyzed numerically using a full Navier-Stokes program with SST turbulence model. The performance characteristics of the compressor were obtained numerically, which were then compared with the experimental results. The comparison shows good agreement. Furthermore, the effect of area ratio and tip clearance on the performance parameters and flow field was... 

    Performance of elevated energy pile groups with different pile spacing in clay subjected to cyclic non-symmetrical thermal loading

    , Article Renewable Energy ; Volume 172 , 2021 , Pages 998-1012 ; 09601481 (ISSN) Ng, C. W. W ; Farivar, A ; Gomaa, S. M. M. H ; Shakeel, M ; Jafarzadeh, F ; Sharif University of Technology
    Elsevier Ltd  2021
    Abstract
    There is an increasing interest and use of energy foundation worldwide. Full-scale tests, physical model tests at one Earth's gravity and at elevated gravity in a geotechnical centrifuge and numerical simulations have been widely reported in the literature. Almost all studies have focused on single energy piles (EPs) and pile groups subjected to symmetrical thermal loads, although it is not unusual to have energy pile groups stressed by non-symmetrical thermal loads. In this study, a series of non-symmetrical thermal loading centrifuge model tests were conducted in saturated soft clay (OCR = 1.7), which is much vulnerable to temperature changes. The tests aim to investigate the effects of... 

    Theoretical and experimental investigation of design parameter effects on the slip phenomenon and performance of a centrifugal compressor

    , Article Scientia Iranica ; Volume 28, Issue 1 , 2021 , Pages 291-304 ; 10263098 (ISSN) Rajabpour, S ; Hajilouy Benisi, A ; Manzari, M. T ; Sharif University of Technology
    Sharif University of Technology  2021
    Abstract
    Numerous studies have investigated driving equations used to predict the slip factor in centrifugal compressors so far. Inevitably, through these studies, the ow field characteristics have been simplified and the effects of the related parameters have been neglected. The present study, experimentally and numerically, investigates the slip phenomenon in a specific centrifugal compressor with complex blade curves and splitter blades, considering the main effective parameters such as the number of blades, exit angle, etc. To this end, a three-dimensional simulation of the viscous flow field of the compressor via an appropriate turbulence method was performed. In addition, an experimental study... 

    The Simulation and Active Control of a Centrifugal Compressor to Improve Compressor Performance & Reduce Energy Consumption

    , M.Sc. Thesis Sharif University of Technology Jokar, Ali (Author) ; Ghofrani, Mohammad Bagher (Supervisor) ; Zomordian, Rozbeh (Supervisor)
    Abstract
    In this thesis, we consider the simulation and active control of a centrifugal compressor in during surge occurrence. Surge, as an aerodynamic instability in compressors, causes to severe decrease of efficiency and loss of energy and with stabilizing the compressor in this condition, efficiency and system reliability increase. Nowadays, anti surge systems are used for surge avoidance in different industrials. They recycle the compressed gas from compressor down-stream to up-stream in instability condition and cause to exit the operation point from unstable zone. In this thesis, at first compression system is modeled based on Greitzer model and governing equation of compressor shaft in surge... 

    Aerodynamic Optimization of a Four Stage Centrifugal Flow Compressor

    , M.Sc. Thesis Sharif University of Technology Mohammadi Yengejeh, Saba (Author) ; Ghorbanian, Kaveh (Supervisor)
    Abstract
    The performance of centrifugal compressors deviates from its best design point and reaches lower efficiencies by time and conversion of input gas properties such as the pressure, temperature, and mixture characteristics. By the fact that each designed compressor should have a wide range of functionality, redesign and optimization processes take place. One of the challenging methods for improving the performance of centrifugal compressors is to modify aerodynamic passage of gas in impellers in order to achieve better pressure ratio and efficiency. The aims of the current study are to evaluate geometry properties of the blades of the first or the second impeller and even the whole compressor... 

    Evaluation of variable permeability model in simulation of seismic behavior of uniform level and gently sloping sand layers

    , Article Earth Sciences Research Journal ; Volume 24, Issue 3 , 2020 , Pages 328-336 Ghassemi, A ; Seyfi, S ; Shahir, H ; Sharif University of Technology
    Universidad Nacional de Colombia  2020
    Abstract
    In this study, a fully coupled dynamic finite element model was employed for numerical simulation of the response of level to gently sloping saturated sand layers subjected to cyclic loading. This model utilized a critical state two-surface-plasticity constitutive model to simulate the cyclic behavior of sandy soil. Moreover, a recently proposed variable permeability function was implemented in the numerical model to reflect the effects of soil permeability variations during the liquefaction phenomenon. The numerical model was validated by simulating a number of well-documented geotechnical centrifuge tests with different relative density of sand, base acceleration time history, and surface... 

    Experimental and numerical investigation of a centrifugal compressor

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 447-458 ; 9780791849170 (ISBN) Karrabi, H ; Hajilouy Benisi, A ; Nili Ahmadabadi, M ; Sharif University of Technology
    2010
    Abstract
    In this research, centrifugal compressor of a gas turbine is investigated experimentally and numerically. Operation line of the compressor as a component of the gas turbine is obtained experimentally by measurements of impeller rotational speed, and flow parameters at the compressor inlet and outlet during the gas turbine operation. The flow field inside the impeller and diffusers are analyzed numerically using a full 3D Navier-Stokes program with SST turbulence model. Boundary conditions for the numerical simulation are specified from the experimental measurements. The operation line of the compressor is obtained numerically, which is compared with that of the experimental results, and... 

    A novel QUASI-3D design method for centrifugal compressor meridional plane

    , Article Proceedings of the ASME Turbo Expo, 14 June 2010 through 18 June 2010 ; Volume 7, Issue PARTS A, B, AND C , 2010 , Pages 919-931 ; 9780791844021 (ISBN) Nili Ahmadabadi, M ; Durali, M ; Hajilouy Benisi, A ; Sharif University of Technology
    Abstract
    This paper is concerned with a quasi-3D design method for centrifugal compressor impeller in the meridional plane. The method links up a novel inverse design algorithm, called Ball-Spine Algorithm (BSA), and a quasi-3D analysis code. The Euler equation is solved on the meridional plane for a numerical domain of which some unknown boundaries (hub and shroud) are iteratively modified under the BSA until a prescribed pressure distribution is reached. In BSA, the unknown walls are composed of a set of virtual balls that move freely along the specified directions called spines. The difference between target and current pressure distribution causes to deform flexible boundary at each modification... 

    Estimating liquefaction-induced settlement of shallow foundations by numerical approach

    , Article Computers and Geotechnics ; Volume 37, Issue 3 , April , 2010 , Pages 267-279 ; 0266352X (ISSN) Shahir, H ; Pak, A ; Sharif University of Technology
    2010
    Abstract
    Occurrence of liquefaction in saturated sand deposits underlying foundation of structure can cause a wide range of structural damages starting from minor settlement, and ending to general failure due to loss of bearing capacity. If the bearing capacity failure is not the problem, reliable estimation of the liquefaction-induced settlement will be of prime importance in assessment of the overall performance of the structure. Currently, there are few procedures with limited application in practice for estimation of settlement of foundations on liquefied ground. Therefore, development of a general relationship is important from the practical viewpoint. In this paper, the dynamic response of... 

    A new analytical model of a centrifugal compressor and validation by experiments

    , Article Journal of Mechanics ; Volume 26, Issue 1 , 2010 , Pages 37-45 ; 17277191 (ISSN) Pourfarzaneh, H ; Hajilouy Benisi, A ; Farshchi, M ; Sharif University of Technology
    2010
    Abstract
    In 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... 

    Effect of splitter leading edge location on performance of an automotive turbocharger compressor

    , Article Energy ; Volume 123 , 2017 , Pages 511-520 ; 03605442 (ISSN) Moussavi, S. A ; Hajilouy Benisi, A ; Durali, M ; Sharif University of Technology
    Elsevier Ltd  2017
    Abstract
    Design of centrifugal compressors can be accomplished using methods provided in text books and open literature. In this general approach, after determination of dimensions in meridional plane, blade profiles are designed using aerodynamic methods. Then, some blades are trimmed at the beginning to avoid inlet blockage. But there is no clear guidance on how this trimming must be performed. With this widely implemented method, splitter blades have the same profile as main ones. In this research, blade profiles and dimensions of the compressor impeller are not changed while the effect of changes in the position and angle of splitters leading edge are investigated. An optimization scheme is... 

    Validity of menard relation in dynamic compaction operations

    , Article Proceedings of the Institution of Civil Engineers: Ground Improvement ; Volume 162, Issue 1 , 2009 , Pages 37-45 ; 17550750 (ISSN) Ghassemi, A ; Pak, A ; Shahir, H ; Sharif University of Technology
    2009
    Abstract
    Dynamic compaction (DC) is a common soil improvement technique, used extensively worldwide. DC treatment design is usually based upon empirical relations and past experience. The common problem with all empirical relations is oversimplification of the mechanisms, and the use of parameters that are highly dependent on engineering judgement. In this paper, a developed finite-element code is used for modelling the impact behaviour of dry and moist sandy soil. The code is verified against the results of centrifuge tests. Then the validity of the popular Menard empirical relation for determination of improvement depth in DC design is investigated. The effect of initial relative density, tamper... 

    Numerical simulation of mixing and heat transfer in an integrated centrifugal microfluidic system for nested-PCR amplification and gene detection

    , Article Sensors and Actuators, B: Chemical ; Volume 283 , 2019 , Pages 831-841 ; 09254005 (ISSN) Naghdloo, A ; Ghazimirsaeed, E ; Shamloo, A ; Sharif University of Technology
    Elsevier B.V  2019
    Abstract
    Nucleic acid amplification via polymerase chain reaction (PCR) is one of the essential and powerful methods used in a myriad of bio-assays in clinical laboratories. Application of microfluidic devices in biologically-related processes like PCR can result in the usage of less volume of reactant samples and reduce the processing time. By implementing PCR systems on centrifugal microfluidic platforms, automation and portability can be easily achieved. Although several methods have been developed, most of them are still dealing with challenges of the required high processing time. This study presents the numerical simulation of a fully automated PCR system with the goal of enhancing the mixing... 

    Experimental and theoretical investigation of centrifugal compressor performance characteristics

    , Article Proceedings of the ASME Turbo Expo, 9 June 2008 through 13 June 2008, Berlin ; Volume 6, Issue PART B , 2008 ; 9780791843161 (ISBN) Motavalli, M ; Hajilouy Benisi, A ; Nili Ahmadabadi, M ; International Gas Turbine Institute ; Sharif University of Technology
    2008
    Abstract
    Prediction of compressor performance is a basic step in design of this turbomachine, while designer can optimize plan by considering various conditions and calculating machine performance. Flow field in centrifugal compressor is threedimensional and intricate. Since 2-D and 3-D methods are very costly, consequently the mean line method usually is used for predicting compressor performance. The energy loss coefficients are used for this method. Because of the intricacy in flow and analysis of losses, most energy loss coefficients are attained by experimental procedures, however just some of them are determined according to theory and nature of the flow field. The purpose of this work is... 

    A new detection chamber design on centrifugal microfluidic platform to measure hemoglobin of whole blood

    , Article SLAS Technology ; Volume 26, Issue 4 , 2021 , Pages 392-398 ; 24726303 (ISSN) Mahmodi Arjmand, E ; Saadatmand, M ; Eghbal, M ; Bakhtiari, M. R ; Mehraji, S ; Sharif University of Technology
    SAGE Publications Inc  2021
    Abstract
    Undoubtedly, microfluidics has been a focal point of interdisciplinary science during the last two decades, resulting in many developments in this area. Centrifugal microfluidic platforms have good potential for use in point-of-care devices because they take advantage of some intrinsic forces, most notably centrifugal force, which obviates the need to any external driving forces. Herein, we introduce a newly designed detection chamber for use on microfluidic discs that can be employed as an absorbance readout step in cases where the final solution has a very low viscosity and surface tension. In such situations, our chamber easily eliminates the air bubbles from the final solution without... 

    Numerical investigation of the effects of soil densification on the reduction of liquefaction-induced settlement of shallow foundations

    , Article Scientia Iranica ; Volume 16, Issue 4 A , 2009 , Pages 331-339 ; 10263098 (ISSN) Shahir, H ; Pak, A ; Sharif University of Technology
    2009
    Abstract
    The liquefaction phenomenon is usually accompanied by a large amount of settlement. Based on the observations made in past earthquakes, ground improvement by densification is one of the most useful approaches to reduce the liquefaction-induced settlement. Currently, there is no analytical solution for evaluation of the amount of settlement and tilting of footings that are constructed on densified ground surrounded by liquefiable soil. A number of factors, such as underlying soil properties, dimensions of the footing and earthquake loading characteristics, cause the problem to become complicated. In this paper, the dynamic response of shallow foundations on both liquefiable and...