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Data publikacji: 4 czerwca 2021
Data aktualizacji: 27 lipca 2024

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1

Harris, P. K. "Erosion in centrifugal compressor impellers". Thesis, Cranfield University, 1996. http://dspace.lib.cranfield.ac.uk/handle/1826/10622.

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An experimental and theoretical study of erosion in centrifugal compressor impellers is presented. An experimental rig using laser anemometry techniques was employed to create a database of particle restitution ratios for a range of materials. This data was unique in that the particle rebound was measured in a quiescent condition where the aerodynamic effects had been minimised, and also parametric factors not previously available were included. These values were incorporated into the existing Particle Trajectory Code developed by Cranfield University and Rolls Royce PLC. The code is used to calculate the trajectories of discrete particles in three dimensional gas turbine geometries, and the ensuing erosion. It was modified to include the effects of the periodic boundary conditions, particle fragmentation, splitter blades, and variations in inlet dust concentration profile. Flowfield calculations were performed on a Rolls Royce GEM-2 and splittered GEM-60 impeller, which both represent the high pressure stage of the axial + centrifugal compression system of GEM engines. A procedure developed by Tourlidakis, for the analysis of steady viscous flow in high speed centrifugal compressors with tip leakage, was used to generate the flowfields. The GEM-2 impeller flowfield was analysed at 1009c speed, and validated with calculations and measurements which had been taken for previous projects. Simulated erosion data under the same conditions was checked using practical results obtained in a Rolls Royce PLC Helicopter Engine Environmental Protection Programme, and good agreement was achieved. In order to provide a qualitative, experimental assessment of erosion, a GEM-60 impeller was coated with four layers of paint of different colours. Two sizes of quartz particle, each at three different vane heights, were then seeded into the impeller while it was run cold at (the maximum) 70% speed. The erosion patterns generated compared well with the results generated by the Particle Trajectory Code.
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2

Visser, Franciscus Cornelis. "On the flow in centrifugal impellers". Enschede : University of Twente [Host], 1996. http://doc.utwente.nl/32024.

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3

Rose, Martin George. "Flow in centrifugal water pump impellers". Thesis, University of Cambridge, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253798.

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4

Початко, Тетяна Володимирівна, Татьяна Владимировна Початко, Tetiana Volodymyrivna Pochatko i M. Voshchenko. "Technological regulations of the multistage pump impellers". Thesis, Sumy State University, 2016. http://essuir.sumdu.edu.ua/handle/123456789/47236.

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Almost half of all energy produced in the country feeds the rotary machines - pumps and compressors. Their usage in all industries is a wide range, depending on their function. Moreover, the current challenges require the energy efficiency of such units’ designs, increasing the requirements for vibration performance, reliability and impermeability. Nowadays the types of manufacturing systems, based on knowledgebased technologies, output the information to the level of the most important resource. They make it a growing factor of production efficiency. Information resource status has become an integral part of the production process alone with material factors of production.
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5

Adkins, Douglas Ray Brennen Christopher E. Brennen Christopher E. "Analyses of hydrodynamic forces on centrifugal pump impellers /". Diss., Pasadena, Calif. : California Institute of Technology, 1986. http://resolver.caltech.edu/CaltechETD:etd-03262007-111453.

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6

Morris, Mary Beth. "Flow randomness and tip losses in transonic rotors". Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-07212009-040241/.

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7

Linn, Linsey Margaret. "Heat transfer in mixing vessels using induction heated impellers". Thesis, University of Bradford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253836.

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8

Ferry, William Benjamin Stewart. "Virtual five-axis flank milling of jet engine impellers". Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/993.

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This thesis presents models and algorithms necessary to simulate the five-axis flank milling of jet-engine impellers in a virtual environment. The impellers are used in the compression stage of the engine and are costly, difficult to machine, and time-consuming to manufacture. To improve the productivity of the flank milling operations, a procedure to predict and optimize the cutting process is proposed. The contributions of the thesis include a novel cutter-workpiece engagement calculation algorithm, a five-axis flank milling cutting mechanics model, two methods of optimizing feed rates for impeller machining tool paths and a new five-axis chatter stability algorithm. A semi-discrete, solid-modeling-based method of obtaining cutter-workpiece engagement (CWE) maps for five-axis flank milling with tapered ball-end mills is developed. It is compared against a benchmark z-buffer CWE calculation method, and is found to generate more accurate maps. A cutting force prediction model for five-axis flank milling is developed. This model is able to incorporate five-axis motion, serrated, variable-pitch, tapered, helical ball-end mills and irregular cutter-workpiece engagement maps. Simulated cutting forces are compared against experimental data collected with a rotating dynamometer. Predicted X and Y forces and cutting torque are found to have a reasonable agreement with the measured values. Two offline methods of optimizing the linear and angular feeds for the five-axis flank milling of impellers are developed. Both offer a systematic means of finding the highest feed possible, while respecting multiple constraints on the process outputs. In the thesis, application of these algorithms is shown to reduce the machining time for an impeller roughing tool path. Finally, a chatter stability algorithm is introduced that can be used to predict the stability of five-axis flank milling operations with general cutter geometry and irregular cutter-workpiece engagement maps. Currently, the new algorithm gives chatter stability predictions suitable for high speed five-axis flank milling. However, for low-speed impeller machining, these predictions are not accurate, due to the process damping that occurs in the physical system. At the time, this effect is difficult to model and is beyond the scope of the thesis.
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9

Seyed, Mahmoudi Seyed Mohammad. "Velocity and mixing characteristics of stirred vessels with two impellers". Thesis, King's College London (University of London), 1993. https://kclpure.kcl.ac.uk/portal/en/theses/velocity-and-mixing-characteristics-of-stirred-vessels-with-two-impellers(b0de9b2e-70e2-4133-9d3e-3955562edfb0).html.

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10

Wahba, Waleed A. "Design optimisation of centrifugal pump impellers using parallel genetic algorithm". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10708.

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Computational Fluid Dynamics (CFD) techniques have settled to a stage, where it is possible to gain significant insight into fluid flow processes of turbomachinery. However, the purpose of fluid dynamics naturally goes beyond improved understanding to the aim of improving the performance of the engineering systems. Consequently, the present thesis investigates the use of a automated design optimisation method using CFD. This presents a new design method for a important turbomachinery part, blade profiles of centrifugal pump impellers, based on a shape optimisation algorithm in combination with CFD. The use of genetic algorithms in shape optimisation dose not allow the design engineer to use any derivative information on the evolution of the shape, but only simple evaluation techniques. A optimisation library (GAlib), based on a genetic algorithm (GA), was used. GA controls the evolution of a population of profiles towards an optimum design. The optimisation process can handle simple objectives as well as conicting ones. The fitness value of each population element is evaluated using a CFD flow solver (Mac_LNS) based on nite-difference discretisation of the incompressible, Navier-Stokes (N-S) equations on structured polar-coordinate meshes. A number of design examples have been developed and the behaviour of the genetic algorithm has been tested using different kinds of objective functions. I addition, the algorithm was tested with a multi-objective mction. Bézier curves were selected to represent the impeller profile. A symmetric profile, identical profile for the pressure side (PS) and suction side (SS), was used as a basic shape to generate the population elements. GAlib was modified to run as a parallel algorithm using Message Passing Interface (MPI). It is indicated that parallelisation using MPI is good technique to overcome the time taken by GA and CFD, and quite good optimisation convergence criteria was obtained by using parallelisation. The obtained results show that the genetic algorithm is capable of achieving satisfactory designs of centrifugal impeller blade profiles effectively and with a minimum amount of user expertise.
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11

Whitton, M. J. "Gas liquid mixing in tall vessels fitted with multiple impellers". Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312190.

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12

Wahba, Waleed. "Design optimisation of centrifugal pump impellers using parallel genetic algorithm". Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/10708.

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Computational Fluid Dynamics (CFD) techniques have settled to a stage, where it is possible to gain significant insight into fluid flow processes of turbomachinery. However, the purpose of fluid dynamics naturally goes beyond improved understanding to the aim of improving the performance of the engineering systems. Consequently, the present thesis investigates the use of a automated design optimisation method using CFD. This presents a new design method for a important turbomachinery part, blade profiles of centrifugal pump impellers, based on a shape optimisation algorithm in combination with CFD. The use of genetic algorithms in shape optimisation dose not allow the design engineer to use any derivative information on the evolution of the shape, but only simple evaluation techniques. A optimisation library (GAlib), based on a genetic algorithm (GA), was used. GA controls the evolution of a population of profiles towards an optimum design. The optimisation process can handle simple objectives as well as conicting ones. The fitness value of each population element is evaluated using a CFD flow solver (Mac_LNS) based on nite-difference discretisation of the incompressible, Navier-Stokes (N-S) equations on structured polar-coordinate meshes. A number of design examples have been developed and the behaviour of the genetic algorithm has been tested using different kinds of objective functions. I addition, the algorithm was tested with a multi-objective mction. Bézier curves were selected to represent the impeller profile. A symmetric profile, identical profile for the pressure side (PS) and suction side (SS), was used as a basic shape to generate the population elements. GAlib was modified to run as a parallel algorithm using Message Passing Interface (MPI). It is indicated that parallelisation using MPI is good technique to overcome the time taken by GA and CFD, and quite good optimisation convergence criteria was obtained by using parallelisation. The obtained results show that the genetic algorithm is capable of achieving satisfactory designs of centrifugal impeller blade profiles effectively and with a minimum amount of user expertise.
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13

Kanel, Jeffrey Scott. "Minimum impeller speeds and power requirements for complete dispersion of non-Newtonian liquid-liquid systems in baffled vessels". Thesis, Georgia Institute of Technology, 1986. http://hdl.handle.net/1853/11256.

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14

Mc, Laughlin Declan T. "Gas entrainment into viscous polymer solutions". Thesis, Queen's University Belfast, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252316.

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15

Haam, Seungjoo. "Local heat transfer in a mixing vessel using heat flux sensors". The Ohio State University, 1990. http://rave.ohiolink.edu/etdc/view?acc_num=osu1102528786.

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16

Curran, Stephen J. "Laminar mixing of a yield stress fluid using helical ribbon impellers". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0003/MQ34349.pdf.

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17

Wong, Vui-Hong, i n/a. "Finite Element Analysis and Improvement of Impeller Blade Geometry". Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20030825.150853.

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Stratification of water in large reservoirs occurs in summer, or at anytime in hot climates where the water surface is exposed long-term to sunlight and the water surface is heated. Natural mixing will not occur due to the cooler and denser water always staying at the lower levels. Therefore, mechanical circulators are designed to prevent water quality problems related to stratification and depletion of dissolved oxygen. Impellers that produce the flow in mechanical circulators are available in different sizes and these impellers are designed to produce different flow rates. Due to hydraulic loadings, impellers have to be strong and durable. Loadings on impellers depend on their geometries and therefore, a durable impeller is a good combination of the use of correct materials and good geometry. Long and slender impellers are prone to failure when subjected to high hydrodynamic loadings. Nowadays, designers have very limited information on predicting the stresses on impellers and the deflection patterns of impellers because there are no design rules in designing these impeller blades and there is no such thing as "best geometry". A good impeller blade design is by guesswork and experience. In order to design the geometry that suits this application, trial-and-error finite element analyses have been conducted in this project to minimize stress levels on the blades. This research involves the use of finite element analysis (FEA) to predict stress and deflection of impeller blades used on large (5m diameter) ducted axial flow impellers as the first step in the design process. Then, based on the results, improvements have been done to the models until the final design was made. As far as the author has been able to determine, this has not been researched before. Finite Element Analysis has been used on wind turbine blades, rudders and hulls of boats but not on axial flow impeller blades of the type used in this project. For the purpose of this project, commercial finite element computer program packages STRAND6 and STRAND7 were used as the main analysis tools. A static line load increasing linearly with radius along the blade has been used to simulate the assumed hydrodynamic loading, and applied to all FEA blade models. The analysis results proved the stresses on blades are largely dependant on the blade geometry. From the analysis results, the author modified the stacking arrangement of the FEA elements in order to minimize both the tensile stresses and the displacements of the blades at the tip. Parametric studies have been done in order to obtain the best FEA impeller blade model.
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18

Wong, Vui-Hong. "Finite Element Analysis and Improvement of Impeller Blade Geomtery". Thesis, Griffith University, 2003. http://hdl.handle.net/10072/367302.

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Stratification of water in large reservoirs occurs in summer, or at anytime in hot climates where the water surface is exposed long-term to sunlight and the water surface is heated. Natural mixing will not occur due to the cooler and denser water always staying at the lower levels. Therefore, mechanical circulators are designed to prevent water quality problems related to stratification and depletion of dissolved oxygen. Impellers that produce the flow in mechanical circulators are available in different sizes and these impellers are designed to produce different flow rates. Due to hydraulic loadings, impellers have to be strong and durable. Loadings on impellers depend on their geometries and therefore, a durable impeller is a good combination of the use of correct materials and good geometry. Long and slender impellers are prone to failure when subjected to high hydrodynamic loadings. Nowadays, designers have very limited information on predicting the stresses on impellers and the deflection patterns of impellers because there are no design rules in designing these impeller blades and there is no such thing as "best geometry". A good impeller blade design is by guesswork and experience. In order to design the geometry that suits this application, trial-and-error finite element analyses have been conducted in this project to minimize stress levels on the blades. This research involves the use of finite element analysis (FEA) to predict stress and deflection of impeller blades used on large (5m diameter) ducted axial flow impellers as the first step in the design process. Then, based on the results, improvements have been done to the models until the final design was made. As far as the author has been able to determine, this has not been researched before. Finite Element Analysis has been used on wind turbine blades, rudders and hulls of boats but not on axial flow impeller blades of the type used in this project. For the purpose of this project, commercial finite element computer program packages STRAND6 and STRAND7 were used as the main analysis tools. A static line load increasing linearly with radius along the blade has been used to simulate the assumed hydrodynamic loading, and applied to all FEA blade models. The analysis results proved the stresses on blades are largely dependant on the blade geometry. From the analysis results, the author modified the stacking arrangement of the FEA elements in order to minimize both the tensile stresses and the displacements of the blades at the tip. Parametric studies have been done in order to obtain the best FEA impeller blade model.
Thesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
Full Text
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19

Peron, Yannick L. "Mixing of immobilised cells in bioreactors". Thesis, University of Huddersfield, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.286090.

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20

Fentiman, Nina Jane. "An experimental study of the mixing and hydrodynamic characteristics of hydrofoil impellers". Thesis, King's College London (University of London), 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312993.

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21

Basbug, Salur. "Flow field and mixing in stirred vessels with regular and fractal impellers". Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/58102.

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The goal of this thesis is to explore the potential benefits of fractal objects in dynamic mixing applications. To this end, the performance of an impeller with fractal blades was evaluated and compared to the one with regular, rectangular-shaped blades. Direct Numerical Simulations (DNS) were performed to compute the flow and passive scalar fields inside an unbaffled stirred vessel in the transitional flow regime. It was observed that at Re=1600 the mean power consumption decreases by ca. 8% when the regular blades are replaced by fractal ones. The physical explanation for this reduction was provided by comparing several characteristics of the flows generated by the two types of impellers, such as the pressure distribution on blade surfaces, the time-average recirculation pattern and the trailing vortex system in wake of the blades, the radial transport of angular momentum and the distribution of energy dissipation inside the tank. Furthermore, fluctuations were observed in the power consumption with a peak frequency at ca. three times the impeller rotational speed, for both impeller types. It was discovered that these fluctuations are associated with a periodic event in the wake of the blades, which involves alternating growth and decay of the upper and lower cores of the trailing vortex pair as well as up-and-down swinging motion of the radial jet. Moreover, the mixing time required to homogenize an injected passive scalar was evaluated for both impeller types, at Sc=1. It was observed that the fractal impeller can lead to a shorter mixing time by 10-12%. This result was explained by the differences in characteristics of flow and scalar fields generated by regular and fractal blades. A simple mathematical model was suggested which is able to approximate the decay rate of the passive scalar fluctuations integrated over the tank volume.
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22

John, Arwyn. "A novel reactor with two independently-driven impellers for gas-liquid processing". Thesis, University of Birmingham, 1998. http://etheses.bham.ac.uk//id/eprint/1425/.

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Filamentous micro-organisms, grown in submerged culture, are used in a large number of fermentation processes, such as the production of penicillin and citric acid. Generally, production takes place in baffled sparged vessels agitated by either single or multiple impellers, traditionally Rushton turbines mounted on a common shaft. This configuration is satisfactory for low viscosity systems, e.g. yeast and some bacterial fermentations. However, in cultures of filamentous fungi, as the fermentation time progresses, the broth may become increasingly viscous, and possibly shear thinning, with the consequent onset of dead zones or stagnant regions. The resulting concentration gradients may cause a reduction in the productivity. It may be possible to overcome these problems by using a fermenter which has two independently driven impellers and a cylindrical draft tube (IDDIDT i.e. an acronym for "Independently Driven Dual Impeller with Draft Tube") Studies have been undertaken in a 0.75 m Perspex proto-fermenter employing a Rushton turbine (6RT) and a Scaba 3SHP1 axial flow impeller, with test fluids such as water and CMC, under unaerated and aerated conditions. In order to fully characterise the system, important mixing aspects such as mass transfer (hold-up, k\(_L\)a) and bulk blending (mixing times, circulation time distributions) were investigated and related to the power input from each impeller. At low gas rates, moderately increased hold-up and k\(_L\)a values were observed with the IDDIDT compared to single or dual Rushton turbine systems. At higher gassing rates the performance was similar for all configurations. For the IDDIDT, regardless of the proportion of the total energy dissipation rate contributed by each impeller, the k\(_L\)a was the same. In addition, very rapid mixing times approximately 3 times faster than predicted by correlations for single impeller, single shaft systems and experimentally determined values for the dual Rushton system, were observed. Mixing times could be directly controlled by the 3SHP1 axial flow impeller, and confirmation of the increased exchange flow rate throughout the vessel was achieved via circulation time distribution (CTD) experiments. Since very little data has been published regarding the use of fermentation broths in these systems, hygienic Aspergillus niger fermentations were carried out in the fermenter to clarify any improvements when using the novel reactor and also to highlight any discrepancies in the use of test fluids, such as CMC, as model broths. Although unaerated and aerated power characteristics were similar for both the test fluids and fermentation broths the hold-up values varied considerably, probably due to differing coalescence characteristics. Productivity (g/l/kWh) of batch phase Aspergillus niger fermentations was unaffected by system geometry, at least up to concentrations of circa 15 g/1.
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23

Jery, Belgacem Brennen Christopher E. Brennen Christopher E. Acosta Allan J. Caughey Thomas Kirk. "Experimental study of unsteady hydrodynamic force matrices on whirling centrifugal pump impellers /". Diss., Pasadena, Calif. : California Institute of Technology, 1987. http://resolver.caltech.edu/CaltechETD:etd-03262007-130547.

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24

Lupi, Alessandro. "CFD analysis and redesign of centrifugal impeller flows for rocket pumps". Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06302009-040325/.

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25

Silva, Lima Jose Aldo. "A numerical model for three dimensional viscous flows aimed at centrifugal pump impellers". Thesis, Cranfield University, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332933.

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26

Cui, Dingjun. "An investigation of the performance of small high-speed electric motor/fan units". Thesis, University of Strathclyde, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366918.

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27

Gamez, Victor Manuel. "Mechanics of batch slurry mixing by means of rotating impellers in a cylindrical vessel". FIU Digital Commons, 1998. http://digitalcommons.fiu.edu/etd/3446.

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Two slurries with solids concentration of 5 % (wt) and 20 % (w.), with approximate chemical and physical properties of melter feeds found in the Defense Waste Processing Facility of the Savannah River Site were prepared, characterized and mixed in a cylindrical vessel with impellers of different diameters pumping the flow in two different axial directions. The electrical power consumed by each impeller was measured and compared for both slurries. A sampling mechanism consisting of tubes positioned parallel to the vertical axis of the tank was also implemented to ascertain the level of homogeneity developed in the mix. The effects of the diameter of the sampling tubes and the sampling speed were evaluated for different impeller rotational speeds acting on the two slurries. Different startup techniques from a fully-settled condition were also assessed. Results indicate significantly lower power consumption when the impeller pumps the fluid downwards, more representative samples when the sampling tube diameter and sampling velocity are increased, and the lowest consumption of power at the startup from fully-settled conditions by the injection of air in the bed of solids.
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28

McKinlay, Ryan Neal. "An Investigation into the Performance of Axial Flow Refrigerator Fans". Thesis, University of Canterbury. Mechanical Engineering, 2014. http://hdl.handle.net/10092/9587.

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This work was concerned with the aerodynamic and acoustic performance of small axial flow refrigerator fans. Relevant literature focusing on the principles of fan noise generation and fan system elements that contribute to noise generation was identified and discussed. A plenum chamber test rig was designed and constructed following ISO 10302-1. A range of 200 mm diameter pressed aluminium Air-Drive fans, commonly used in commercial refrigerator systems, were evaluated using the test rig. It was found that the performance of these fans was highly dependent upon the impedance of the system in which they are installed. Indications of rotating stall under high load were observed and shown to significantly increase the noise output of the fan without greatly affecting the air moving capability. A series of novel colour map plots are presented, which allow for a visual interpretation of fan performance over a wide range of operating conditions. A fanpack developed by Wellington Drive Technologies Ltd was evaluated. This fanpack was found to generate significant tonal noise. The design of the fanpack was evaluated and improvements are suggested. Prototype fans were developed from the fanpack based on promising concepts presented in the literature. The performance of four prototype fans was evaluated. The results were disappointing, but proof of concept was demonstrated.
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29

Sossa, Jaime Alberto. "Experimental and computational study of mixing behavior in stirred tanks equipped with side entry impellers". Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/42158.

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The wide applicability of mechanically stirred tanks in industry demands a comprehensive understanding of the physical and chemical phenomena controlling the performance of these fundamental units. The rheological complexity of some industrial fluids can create unfavorable mixing environments like dead zones that limit the contact area among the components being mixed. Also, the complex three dimensional nature of the flow generated by the impellers makes difficult the prediction of the flow properties, especially when the fluid viscosity is a function of the shear rate. Some research groups have investigated mixing flow of these kinds of fluids in conventional stirred tanks with top-entry impellers. But, little has been done to characterize the flow behavior in tanks with side-entry impellers. In order to improve our understanding and provide insight into the flow mixing occurring in stirred tanks with side entry impellers, the flow field generated by different impellers in scale-down vessels filled with glycerine and carbopol solutions, was studied using the flow visualization technique, particle image velocimetry (PIV). Moreover, a computational model was built to predict flow variables and mixing characteristics unattainable with the experimental technique. The capabilities of the model were evaluated based on the velocity fields obtained experimentally. Good agreement was found between the predicted and measured macroscale flow structures and global mixing parameters. However, the models were unable to predict the symmetric flow observed during the experiments at high rotational speeds, likely due to the approach taken to simulate the flow, which provides a steady state velocity profile for one specific impeller location Overall the results showed the formation of dead zones and segregated regions when mixing the non-Newtonian solutions. The size of the dynamic regions and the average velocity near the impeller were improved by increasing the suction area. Likewise, large pitch ratios were found to enhance the active mixing zone and the axial discharge. While, radial discharge and a strong tangential flow arose when the viscous forces dominate the flow. In conclusion, the flow features were defined by the Reynolds number in the vicinity of the impeller and the restrictions imposed by the walls of the vessel.
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30

Nishta, B. V. "Computer analysis of the stress-deformation state of the centrifugal compressor and gas turbine impellers". Thesis, Sumy State University, 2015. http://essuir.sumdu.edu.ua/handle/123456789/40623.

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Impellers are rotating components of a centrifugal compressor and gas turbine. Sometimes they have complex forms. They are mainly loaded by centrifugal forces. The wheels are heavy duty parts, often working for long time and their summary stresses may be so large that the analysis of the conditions of their strength is impossible without considering creep. At the same time the wheels are the most critical parts of machines and saving their strength should be provided with complete reliability. All this is defined by special difficulties and responsibilities of the compressor and turbine wheel strength calculating.
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31

Hari-Prajitno, Danawati. "An experimental study of single, dual and triple wide-blade hydrofoil impellers : power and homogenisation characteristics". Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.625480.

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Unaerated and aerated power and mixing characteristics were studied in two agitated vessels. In one of 56cm diameter (T 56) single impellers with a liquid height giving an aspect ratio AR of 1 and dual and triple 1 impellers (AR = 2) were used in the turbulent region. In the other of61cm diameter (T61), only single impellers at AR = 1 were studied in water and viscous, non-Newtonian sodium carboxymethylcellulose (CMC) solutions, the latter giving Reynolds numbers in the transitional regime. The axial flow hydrofoil impellers used were APV-B2's (B2-30U, B2-30D and B2-45U) and Lightnin' A-315D and A-315U (U - up-pumping; D - down-pumping). Mixing times and homogenisation were also measured in T56 using a decolourisation technique for dual and triple impeller configurations of APV -B2's under unaerated and aerated conditions. The results are compared with radial 6 blade Rushton turbines (6RT).
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Cartwright, Craig David. "Bioprocess intensification : a study of rotating packed bed porous mesh impellers for enhancement of aerobic fermentation processes". Thesis, University of Newcastle Upon Tyne, 2011. http://hdl.handle.net/10443/1312.

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Oxygen transfer can be a rate limiting factor in aerobic fermentation systems. If oxygen concentration becomes insufficient productivity will decrease and the culture will ultimately die. Novel reactor technology such as the Rotating Packed Bed Reactor (RPB) may overcome this traditional limitation. The exploitation of high centripetal forces and highly porous packing material in the RPB in gas-liquid processes is proposed to enhance oxygen transfer by production of fine bubbles. The aim of the enhancement is to ensure that the Dissolved Oxygen (DO) concentration exceeds the demand of the microbial culture utilised. The purpose of the thesis is the development and characterisation of a new HiGEE Bioreactor (HBR) for application to fermentation systems. The work was undertaken in three stages. Initial experiments focused on the mass transfer characterisation of several porous packings intended for use in the HBR. The performance of the packings was evaluated by measuring their oxygen transfer capability, power input and air bubble size produced when employed as impellers in a conventional gas-liquid stirred tank reactor (STR). It was observed that the 11 cm stainless steel Knitted Wire mesh impeller (at a fixed airflow rate of 1.0 vvm, and agitation rate of 400 rpm) produced a KLa value of 0.0312 s-1 compared to KLa of 0.0334 s-1 for the double Rushton turbine at an agitation rate of 1000 rpm and aeration rate of 1.0 vvm but with a significant decrease of about 7000 W m-3 in power. Similarly in the bubble experiments performed, the 11 cm knitted wire impeller could produce bubble diameters as low as 0.15 cm compared to 0.28 cm for the Rushton impeller. Two fermentation systems studied (oxygen transfer optimisation with Escherichia coli K12, and product optimisation with Pseudomonas putida KT2442) further demonstrated that the knitted wire mesh packing could produce a higher biomass concentration due to the enhanced oxygen transfer rate. In the final set of experiments a new HBR was designed and commissioned. A set of hydrodynamic experiments focused on the flooding conditions and bubble sizes produced within the reactor. For both experiments the packing had a profound influence on the results, producing a very fine bubble diameter of 0.361 mm at 1200 rpm with packing compared to 2.50 mm at 1200 rpm without packing whilst also allowing higher throughputs of liquid and gas before flooding occurred. A series of transfer studies also illustrated the effect of packing, with a KLa value of 0.0025 s-1 (no packing) and 0.0030 s-1 (with packing) achieved for an experiment at 1200 rpm. The RPB was then tested to be utilised as a bioreactor by studying the fermentation of P.putida KT2442 to produce polyhydroxyalkonates (PHA).
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Al-Azzawi, Mohammad Mousa. "An advanced finite element system for static and dynamic analysis, with application to the design of radial impellers". Thesis, Cranfield University, 1987. http://dspace.lib.cranfield.ac.uk/handle/1826/5713.

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An advanced finite-element package, tailored to the static and dynamic analysis of radial impellers has been produced. Two families of new elements, one for thin and thick plates and the other for thin and thick shells, have been derived and proved to perform very well within a wide range of structural thicknesses. Static and dynamic economical solvers, two- and three-dimensional mesh generation and plotting, sectorial symmetric analysis, steady state response, transient response, and other programs are part of the large number of facilities available in the package. The finite-element package has been validated by solving a large number of simple case studies and comparing the package results with those obtained from analytical solutions. Two different radial impeller, experimental validation tests have been carried out, the first being the dynamic analysis of a radial impeller using the time averaged holographic technique, and the second the measurement of the steady-state stresses by means of a strain-gauge/slip ring assembly for a rotating impeller. The experimental results have been shown to be in good agreement with those obtained from the package.
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Ігнатьєв, Олександр Савич, Александр Савич Игнатьев, Oleksandr Savych Ihnatiev, Максим Васильович Найда, Максим Васильевич Найда i Maksym Vasylovych Naida. "Теории подобия и регулирование параметров лопастных насосов". Thesis, Сумский государственный университет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45584.

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В современной техники широкое распространение получил метод регулирования параметров лопастного насоса путем подрезки (уменьшение) диаметра рабочего колеса. Это удобный и дешевый способ регулирования. Однако при этом надо учитывать, что во многих конструкциях рабочих колес изменяются лопасти в форме профиля переменного сечения. Как известно, линии тока в подобных рабочих колесах имеют аналогичную форму, и частицы жидкости двигающееся по ним имеют аналогичное направление движения и скорости пропорциональные наружному диаметру рабочего колеса. При этом рассматривается условие, что стенки, ограничивающие русло по которому течет жидкость, не имеют толщины.
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Fuhnwi, Godwin Fonguh. "Computational modelling of a smart impeller actuated by shape memory alloys". Thesis, Cape Peninsula University of Technology, 2011. http://hdl.handle.net/20.500.11838/1288.

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Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2011
Smart (SMA-Shape Memory Alloy) Technology continues to advance rapidly as engineers move closer to and understand better the industrial and commercial needs for SMA. As a matter of fact, all types of products, which exercise some type of control over their function, are rapidly making their way into the marketplace [36] Nonetheless, nowhere has been evidence in the development of a SMA impeller. Unlike traditional impellers with no control over their function and sometimes fixed angle of attack, this paper demonstrates numerical investigations using analytical algorithms (Matrix laboratory programming and excel spread sheet) and advanced computer simulation package, Engineering Fluid dynamics (EFD) into the feasibility of using a smart impeller to study the performance of a pumping system and the best angle of attack for a Shape Memory Impeller. Primarily, Bench mark data and dimensions are obtained from a standard centrifugal pump run on a FM21 demonstration unit. Using the same standard centrifugal pump, and keeping all other dimensions the same but altering the angle of attack, EFD simulations where made. From analytical algorithm and EFD comparison, it was evident that the best angle of attack is 12 degree at the outlet angle with respect to the inlet angle. From EFD results, it is palpable that, by increasing the angle of attack from 35 degree to 45 degree at the outlet there will be huge increase in flow rate by 63.47% There is also a slight decrease in the impeller Torque from 35 degrees to 42 degrees by 0.72%. It is economically feasible to work at an outlet angle of 42 degrees due to increase in efficiency of 62.1% and a drop in torque of 0.72% by varying the outlet angle from 35 degrees to 42 degree. Understanding how critical actuator design is, it should be suggested that any shape memory impeller should never be used in critical components without a prior history of thermal and mechanical loading. Therefore, a NiTi impeller constitutive model can be designed, with impeller blades made from NiTi plates, trained to remember its best angle of attack (Martensitic phase). NiTi shape memory metal alloy (plates-blades) can exist in a two different temperature-dependent crystal structures (phases) called martensite [9](lower temperature-normal pumping condition) and austenite [9] (higher temperature or parent phase-trained best angle of attack.)
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36

Кондусь, Владислав Юрійович, Владислав Юрьевич Кондусь, Vladyslav Yuriiovych Kondus i Ю. О. Матвієнко. "Удосконалення конструкції робочого колеса з метою підвищення енергоефективності вільновихрового насоса". Thesis, Сумський державний університет, 2016. http://essuir.sumdu.edu.ua/handle/123456789/45605.

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Основні тенденції розвитку насособудування обумовлені зниженням загальних витрат, до яких входять інвестиційні витрати на придбання устаткування, а також сума витрат, які несе користувач з моменту купівлі до моменту утилізації обладнання. Джерелом зниження експлуатаційних витрат є підвищення енергоефективності насосного обладнання, що досягається за рахунок підвищення к.к.д. насоса шляхом оптимізації конструкції його проточної частини.
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37

Ma, Zheng. "Impeller Power Draw Across the Full Reynolds Number Spectrum". University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1406766474.

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38

Schemmann, Christoph [Verfasser], Carsten [Akademischer Betreuer] Könke, Carsten [Gutachter] Könke, Tim [Gutachter] Ricken i Marius [Gutachter] Geller. "Optimization of Centrifugal Compressor Impellers by a Multi-fidelity Sampling Method Taking Analytical and Empirical Information into Account / Christoph Schemmann ; Gutachter: Carsten Könke, Tim Ricken, Marius Geller ; Betreuer: Carsten Könke". Weimar : Bauhaus-Universität Weimar, 2019. http://d-nb.info/1195444990/34.

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Schemmann, Christoph [Verfasser], Carsten [Akademischer Betreuer] Könke, Carsten Gutachter] Könke, Tim [Gutachter] [Ricken i Marius [Gutachter] Geller. "Optimization of Centrifugal Compressor Impellers by a Multi-fidelity Sampling Method Taking Analytical and Empirical Information into Account / Christoph Schemmann ; Gutachter: Carsten Könke, Tim Ricken, Marius Geller ; Betreuer: Carsten Könke". Weimar : Bauhaus-Universität Weimar, 2019. http://nbn-resolving.de/urn:nbn:de:gbv:wim2-20190910-39748.

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Buffo, Mariane Molina. "Transferência de oxigênio e cisalhamento em biorreator convencional com diferentes combinações de impelidores". Universidade Federal de São Carlos, 2016. https://repositorio.ufscar.br/handle/ufscar/7933.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
The type and operational conditions of a bioreactor chosen during the production phase of a product of interest affect not only the morphology and growth of filamentous microorganisms but also the product itself. Still the most common process to produce bioproducts is submerged cultures in conventional stirred and aerated bioreactors, with impeller of type six flat-blade turbine, or Rushton turbine (RT), which promotes good mixing and suitable oxygen transfer, but its power consumption is high and it causes high shear rate to the broth creating a hostile environment to the microorganisms. Alternatively, an impeller of the type “Elephant Ear” (EE) is shown in the literature as a “low shear” impeller, more suitable for the cultivation of shear sensitive microorganisms. This impeller creates a mixed flow (axial and radial) of broth with down flow (EEDP) or up (EEUP) depending on its geometry. This study aimed to evaluate the best association of impellers for filamentous fungi cultures in a conventional bioreactor. Initially the volumetric coefficient of oxygen transfer (kLa) and the power consumption of seven different association of impellers were evaluated. The results obtained the factorial design methodology showed that the associations EEDP-EEUP, RT-EEDP, and EEDP-RT, showed the best results regarding the oxygen transfer and the power consumption, being up to 87% more efficient than the standard RT-RT association. Two of the better performing association and the traditional (RT-RT) were selected to be evaluated regarding the shearing, by using empirical equations and the size of the eddies, evaluated by the Kolmogorov microscale. The association that showed higher values on the Kolmogorov scale and least shearing was EEDPEEUP, with shearing up to 60% lower than the RT-RT association. In the last step the effects of shear on the morphology of the fungi Aspergillus niger was evaluated. Short-term cultures (4h) were cultivated so that the cellular growth would not harm the analysis. The results showed that on the culture that used the EEDP-EEUP association the morphological form of cell clumps predominated, while on the culture that used the RT-RT association the morphological form of branched hyphae predominated, suggesting that the RT-RT association causes more shearing and can cause irreversible damage to the fungal cells.
O crescimento celular e a morfologia de microrganismos filamentosos, bem como o produto de interesse são afetados pelo modelo de biorreator e pelas condições de operação adotadas durante a etapa de produção. O processo mais adotado industrialmente para produção de bioprodutos ainda são os cultivos submersos em biorreatores convencionais tipo tanque agitado e aerado, sendo o impelidor tipo turbina de seis pás planas ou turbina de Rushton (RT) o mais utilizado por promover boa mistura e adequada transferência de oxigênio, porém seu consumo de potência é alto além de impor alto cisalhamento ao caldo gerando um ambiente hostil ao microrganismo. Alternativamente, o impelidor tipo “orelha de Elefante” ou “Elephant ear” (EE) é apresentado na literatura como um impelidor de “baixo cisalhamento” mais adequado para o cultivo dos microrganismos sensíveis ao cisalhamento. Esse impelidor promove um escoamento misto (axial e radial) do caldo com escoamento para baixo (EEDP) ou para cima (EEUP) dependendo da sua geometria. O presente trabalho teve como objetivo avaliar as melhores associações de impelidores para cultivos de fungos filamentosos em biorreator convencional. Primeiramente sete diferentes associações foram avaliadas em relação ao coeficiente volumétrico de transferência de oxigênio (kLa) e consumo de energia. Os resultados obtidos utilizando a metodologia de planejamento experimental fatorial mostraram que as configurações EEDP-EEUP, RT-EEDP e EEDP-RT foram as que apresentaram melhores resultados em relação à transferência de oxigênio e consumo de potência, com eficiência até 87% superior à associação padrão RT-RT. Foram então selecionadas duas das associações de melhor desempenho e a tradicional (RT-RT) para serem avaliadas em relação ao cisalhamento, através de equações empíricas e em relação ao tamanho dos turbilhões, avaliado pela microescala de Kolmogorov. A associação que apresentou maiores valores para microescala de Kolmogorov e menor cisalhamento foi a EEDP-EEUP, com cisalhamento até 60% inferior que a observada quando utilizada a associação RT-RT. Na última etapa verificou-se os efeitos do cisalhamento na morfologia do fungo Aspergillus niger. Foram realizados cultivos de curta duração (4 h) para evitar que o crescimento celular prejudicasse a análise. Os resultados mostraram que no cultivo utilizando o sistema EEDP-EEUP predominou a forma morfológica de aglomerados celulares (clumps), enquanto que no cultivo com impelidores Rushton (RT-RT) predominou a forma morfológica de hifas ramificadas, sugerindo um cisalhamento mais intenso provocado por este sistema de agitação, que pode acarretar danos irreversíveis às células fúngicas.
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41

Tarr, David Landon. "Scaling of impeller response to impeller-diffuser interactions in centrifugal compressors". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44924.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Includes bibliographical references (p. 119-121).
A numerical investigation has been conducted to quantify the effect of impeller-diffuser interaction on changes in impeller performance. An assessment is made of the hypothesis that the nondimensional parameter characterizing impeller performance change due to interaction is the ratio of the radial gap between the impeller trailing edge and the diffuser leading edge to the diffuser vane pitch. The time averaged results are found to show no measurable performance change with varying degrees of impeller-diffuser interaction, disproving the hypothesis. Analysis of the flow field shows that changes in loss and blockage due to interaction in the region of the blade leakage flow, which were expected to drive performance change, are negligible. The disproven hypothesis lacks parameters to relate the level of impeller passage unsteadiness to the level of performance change due to interaction, which are shown to be important. The ratio of the unsteady amplitude, of blade leakage velocity or blade loading, to the time average value appears to be a parameter capable of quantifying the impact of unsteadiness on impeller performance change.
by David Landon Tarr.
S.M.
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42

Silva, Jefferson Luiz Grangeiro da. "Analise critica das correlações e parametros fundamentais em sistemas de agitação". [s.n.], 2002. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267607.

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Orientadores: Jose Roberto Nunhez, Efraim Cekinski
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica
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Resumo: O projeto atual de agitadores químicos é essencialmente dependente de relações empíricas, visto que as leis fisicas que regem os fenômenos envolvidos nos processos químicos são expressões cuja solução analítica é ainda desconhecida. Devido a isto, trabalhos experimentais como os compilados por Nagata, (1975), Oldshue, (1983), Sano e Usui, (1985) e Tatterson, (1991) são utilizados como principais referências para o cálculo do consumo de energia destes sistemas de agitação. Este projeto de pesquisa tem por objetivo principal compilar na literatura as principais correlações e trabalhos que são utilizados como base para o cálculo convencional de agitadores utilizados na indústria química, de forma que sejam definidas as melhores correlações através da análise dos parâmetros fundamentais (relações geométricas) no cálculo do Número de Potência, Número de Reynolds, Número de Froude, Número de Fluxo, Número de Mistura e o consumo de Potência de impelidores para os sistemas de agitação. A análise dos parâmetros geométricos será particularmente importante para estágios iniciais de projetos de plantas químicas, quando são necessárias informações da geometria, tanto do tanque como do impelidor (agitador) e, principalmente, do consumo de energia específica destes equipamentos para se estimar o consumo de energia da planta. Os resultados analisados através da utilização das correlações empíricas serão comparados com o Software comercial VISIMIX. Adicionalmente o L-CFD, laboratório de Fluído Dinâmica Computacional, já desenvolveu diversos projetos que analisam a otimização de projeto de reatores de mistura utilizando a Fluido Dinâmica Computacional e este projeto contribui por complementar o conhecimento deste grupo de pesquisa sobre o projeto de agitadores através de cálculos convencionais
Abstract: The design of impellers to date depends on empirical relations, since the physical laws that describe the phenomena involved in the chemical processes are expressions whose analytical solution is still unknown. Experimental works as those compiled by Nagata, (1975), Oldshue, (1983), Sano and Usui, (1985) and Tatterson, (1991) are used as references for energy consumption estimation in these systems. The compilation of the main correlations and the works in the literature that are used as a base to the conventional way to ca1culate the main impellers used in the chemical industry is the main objective of this research; which will allow one to select the better correlations it is carried on by the analysis of fundamental paramenters (geometric relations) for the ca1culation of Power Number, Reynolds Number, Froude Number, Flow Number, Mixing Number and the Power consumption of impellers in these systems. The analysis of the geometrical parameters will be particularly important to the early stages in the design of chemical plants, when informations ofthe tank and ofthe impeller (agitator) geometries and, mainly,about the specific energy consumption of these equipments are needed. The results are analysed using empirical correlations in the literature and are compared with the commercial software VISIMIX. Additionaly the L-CFD, Computational Fluid Dynamics laboratory, has already developed several projetcs to analyse the optimization project of mixing tanks, through the use of Computational Fluid Dynamics. This project contributes to complement the knowledge of this group of research on the design of mixing impellers, through the use of conventional methods
Doutorado
Desenvolvimento de Processos Químicos
Mestre em Engenharia Química
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43

Nataša, Lukić. "Samo-rotirajući impeleri u airlift reaktoru sa spoljašnjom recirkulacijom". Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2017. http://www.cris.uns.ac.rs/record.jsf?recordId=102693&source=NDLTD&language=en.

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Cilj doktorske disertacije je poboljšanje hidrodinamičkih imasenoprenosnih karakteristika airlift reaktora saspoljašnjom recirkulacijom umetanjem samo-rotirajućihimpelera u uzlaznu cev. Uticaj ugradnje samo-rotirajućihimpelera na osnovne hidrodinamičke i masenoprenosneosobine ispitivan je pri radu sa različitim tečnostima idistributorima gasa. Rezultati su tumačeni poređenjemvrednosti za sadržaj gasa u uzlaznoj cevi, za brzinutečnosti u silaznoj cevi, i za zapreminski koeficijentprenosa mase, dobijenih za dve konfiguracije reaktora (sai bez impelera).Rezultati disertacije ukazuju da ugradnja samo-rotirajućihimpelera dovodi do znatnog razbijanja mehurova ismanjenja srednjeg prečnika mehurova gasa, naročito uviskoznim rastvorima karboksimetilceluloze. Prividnabrzina gasa, vrsta tečne faze i tip distributora gasa uvelikoj meri utiču na efikasnost samo-rotirajućih impelera.Dobijene vrednosti sadržaja gasa u uzlaznoj cevi su do47% veće u konfiguraciji sa impelerima u odnosu nakonfiguraciju bez impelera. Iako samo-rotirajući impeleripredstavljaju dodatni otpor proticanju tečnosti, njihovomugradnjom je u svim ispitivanim sistemima postignutorelativno malo smanjenje brzine tečnosti (oko 10%).Zahvaljujući impelerima, zapreminski koeficijent prenosamase uvećan je do 82% pri manjim protocima gasa. Privećim protocima, koji odgovaraju uslovima rada koji sesreću u većini fermentacionih procesa, postignute su oko20-30% veće vrednosti zapreminskog koeficijenta prenosamase.Pored empirijskih modela, u ovom radu uspešno surazvijeni i modeli veštačkih neuronskih mreža kojim sepredviđaju sadržaj gasa u uzlaznoj cevi, brzina tečnosti izapreminski koeficijent prenosa mase za obe konfiguracijeairlift reaktora sa spoljašnjom recirkulacijom.
The aim of this study was intensification ofhydrodynamic and mass transfer properties ofexternal-loop airlift reactor by means of self-agitatedimpellers mounted in the riser section. The influenceof impellers’ insertion on the main hydrodynamicand mass transfer characteristics was investigated forvarious liquid phases and sparger types. The valuesof riser gas holdup, downcomer liquid velocity andvolumetric mass transfer coefficient obtained inconfigurations with and without impellers werecompared.Results showed that the installment of self-agitatedimpellers led to a significant bubble breakage anddecrease of bubble size, especially in viscouscarboxymethylcellulose solutions. The efficiency ofself-agitated impellers was immensely influenced bysuperficial gas velocity, liquid phase, and distributortype. Obtained riser gas holdup values were up to47% higher in the configuration with impellers, incomparison to the configuration wthout impellers.Despite the fact that self-agitated impellersrepresented an obstacle to liquid flow, relatively lowreduction of downcomer liquid velocity was attained(about 10%). Furthermore, the insertion of impellersinduced up to 82% higher values of volumetric masstransfer coefficient at lower superficial gas velocities.At higher superficial gas velocities, i.e. conditionsmainly operated in various fermentation processes,about 20-30% higher values of volumetric masstransfer coefficient were achieved with impellers.In addition to empirical correlations, artificial neuralnetwork models were sucessfully developed topredict riser gas holdup, downcomer liquid velocityand volumetric mass transfer coefficient in bothexternal-loop airlift configurations.
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44

Amundsen, Siren Carstens. "Wet Gas Compression : Impeller Rig". Thesis, Norwegian University of Science and Technology, Department of Energy and Process Engineering, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-9976.

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Wet gas compression technology is of great value to the oil and gas industry for boosting of unprocessed well stream and to reduce investment costs related to equipment and personnel. The growing interest in wet gas compression leads to a general request for accurate performance calculation procedures and proper measurement techniques for multiphase flow metering in compressors. An impeller rig for examination of single-phase and multiphase performance and aerodynamic stability is under construction at the test facility at NTNU. The construction of the compressor rig is behind time due to late deliveries of the compressor components and instrumentation. The performance calculations are therefore based upon one compressor test conducted with dry gas at part-load. The thermodynamic equation of state for ambient air is verified to be consistent with the ideal gas law in the compressor pressure and temperature range. The calculated polytropic performance is calculated with ideal gas assumptions and compared to values estimated by PRO/II. By analyzing the results the sensitivity of the calculation procedures is identified and the suitability for the ideal polytropic performance calculations is validated for the actual compressor test and operating range. A sensitivity analysis is conducted in order to determine the effect of measurement uncertainties on performance calculations. Due to the low pressures involved for the compressor test, the performance calculation procedures are highly sensitive to uncertainties in the pressure measurements. Uncertainties in the temperature measurements will only slightly influence the polytropic head, but have great influence on the polytropic efficiency. The efficiency and operating range of a compressor are constrained by aerodynamic instabilities. This thesis describes the different flow phenomena associated with compressor instability and presents recommendations for suitable instrumentation and measuring techniques. Various visualization techniques are in addition evaluated to determine the suitability for multiphase compressors. Dynamic pressure transducers installed in the inlet and discharge piping are recommended for detection of pressure pulsation throughout the compressor system. Unsteady internal pressure measurements can be obtained from circumferentially distributed pressure transducers at various locations within the compressor components. Vibration probes installed at each end of the rotor are recommended for the vibration measurements. By analyzing the frequency spectrum for the pressure fluctuation and radial vibrations one can identify the type of instability phenomenon that occur. Laser measurement techniques are recommended for the flow visualization in order to obtain information on the main features of the multiphase flow field.

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Ahmed, N. A. "Flow studies in impeller passages". Thesis, Cranfield University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234510.

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Kee, Kim Chung. "Particle impacts on impeller blades". Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624407.

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Forrester, Stephanie E. "Hydrodynamics of a gas-inducing impeller". Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362961.

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Shum, Yu Kwong 1968. "Impeller-diffuser interaction in centrifugal compressors". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8594.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2000.
"February, 2000."
Includes bibliographical references (p. 109-114).
A study has been conducted, using an unsteady three-dimensional Reynolds-averaged Navier-Stokes simulation, to define the effect of impeller-diffuser interaction on the performance of a centrifugal compressor stage. The principal finding from the study was that the most influential aspect of this unsteady interaction was the effect on impeller tip leakage flow . In particular, the unsteadiness due to the upstream potential effect of the diffuser vanes led to larger viscous losses associated with the impeller tip leakage flow. The consequent changes at the impeller exit with increasing interaction were identified as reduced slip, reduced blockage, and increased loss. The first two were beneficial to pressure rise while the third one was detrimental. The magnitudes of the effects were examined using different impeller-diffuser spacings and it was shown that there was an optimal radial gap size for maximum impeller pressure rise. The physical mechanism was also determined: when the diffuser was placed closer to the impeller than the optimum, increased loss overcame the benefits of reduced slip and blockage. The findings provide a rigorous explanation for experimental observations made on centrifugal compressors. The success of a simple flow model in capturing the pressure rise trend indicated that although the changes in loss, blockage and slip were due largely to unsteadiness, the consequent impacts on performance were mainly onedimensional. The influence of flow unsteadiness on diffuser performance was found to be less important than the upstream effect, by a factor of seven in terms of stage pressure rise in the present geometry. It is thus concluded that the beneficial effects of impeller-diffuser interaction on overall stage performance come mainly from the reduced blockage and reduced slip associated with the unsteady tip leakage flow in the impeller.
by Yu Kwong Patrick Shum.
Ph.D.
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Shehata, Hussein A. H. "HVAC systems using flexible fibre impeller fans". Thesis, University of Nottingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297764.

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Arellano-Huacuja, A. "Impeller agitated aerobic bioreactor : influence of impeller design on power consumption and gas hold-up structure in highly viscous liquids". Thesis, University of Reading, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.242329.

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