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Dissertations / Theses on the topic 'Turbomachinery flow'

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Published: 10 December 2022
Last updated: 28 January 2023

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1

Evers, Ingmar. "Sound generation in turbomachinery flow." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624316.

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2

Ning, Wei. "Computation of unsteady flow in turbomachinery." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/4819/.

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Unsteady flow analysis has been gradually introduced in turbomachinery design systems to improve machine performance and structural integrity. A project on computation of unsteady flows in turbomachinery has been carried out. A quasi 3-D time-linearized Euler/Navier-Stokes method has been developed for unsteady flows induced by the blade oscillation and unsteady incoming wakes, hi this method, the unsteady flow is decomposed into a steady flow plus a harmonically varying unsteady perturbation. The coefficients of the linear perturbation equation are formed from steady flow solutions. A pseudo-time is introduced to make both the steady flow equation and the linear unsteady perturbation equation time-independent. The 4-stage Runge-Kutta time-marching scheme is implemented for the temporal integration and a cell-vertex scheme is used for the spatial discretization. A 1-D/2-D nonreflecting boundary condition is applied to prevent spurious reflections of outgoing waves when solving the perturbation equations. The viscosity in the unsteady Navier- Stokes perturbation equation is frozen to its steady value. The present time-linearized Euler/Navier-Stokes method has been extensively validated against other well- developed linear methods, nonlinear time-marching methods and experimental data. Based upon the time-linearized method, a novel quasi 3-D nonlinear harmonic Euler/Navier-Stokes method has been developed. In this method, the unsteady flow is divided into a time-averaged flow plus an unsteady perturbation. Time-averaging produces extra nonlinear "unsteady stress" terras in the time-averaged equations and these extra terras are evaluated from unsteady perturbations. Unsteady perturbations are obtained by solving a first order harraonic perturbation equation, while the coefficients of the perturbation equation are forraed from time-averaged solutions. A strong coupling procedure is applied to solve the time-averaged equation and the unsteady perturbation equation simultaneously in a pseudo-time domain. An approximate approach is used to linearize the pressure sensors in artificial smoothing
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3

Pelton, Robert John. "One-Dimensional Radial Flow Turbomachinery Performance Modeling." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd2192.pdf.

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4

Khobeiz, Mohamed Hussien. "Numerical simulation of viscous incompressible turbomachinery flow." Thesis, University of Sheffield, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338828.

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5

Kempe, Andreas. "Low coherence interferometry in turbomachinery and flow velocimetry /." Zürich : Laboratory of Fluiddynamics, Swiss Federal Institute of Technology (ETH) Zürich, 2007. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=16962.

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6

Schulte, Volker Benno. "Unsteady separated boundary layers in axial-flow turbomachinery." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/252035.

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7

Wang, Xiao. "A preconditioned algorithm for turbomachinery viscous flow simulation." Diss., Mississippi State : Mississippi State University, 2005. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.

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8

Addison, John Stephen. "Wake-boundary layer interaction in axial flow turbomachinery." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.357704.

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9

Tiow, Wee Teck. "Inverse design of turbomachinery blades in rotational flow." Thesis, University College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325463.

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10

Birch, N. T. "Turbulence and transition modelling in turbomachinery flows." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.379491.

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11

Udrea, Doina Daciana. "High accuracy flow velocity measurements using particle image velocimetry : development and applications." Thesis, University of Warwick, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300743.

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12

Heinlein, Gregory S. "Aerodynamic Behavior of Axial Flow Turbomachinery Operating in Transient Transonic Flow Regimes." The Ohio State University, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=osu1573149943024303.

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13

Ross, Michael McLean. "Photon correlation velocimetry for the fluid flow through turbomachinery." Thesis, University of Leicester, 1988. http://hdl.handle.net/2381/34819.

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This thesis is concerned with the application of photon correlation velocimetry to the design of products which employ rotating components in fluids. Two examples are considered, viz. The development of turbines and compressors for power generation. The development of propulsor design for use on underwater powered vehicles. The former required the measurement of high speed gas flows (up to Mach 1.8) both within cascades and in a model turbine. The latter entailed tests on models in both a water tunnel and a wind tunnel with flow velocities of up to 15 meters per second and 50 meters per second respectively. In each case a 50 nanosecond digital correlator was used and the optical systems were designed to operate within constraints set by this, the nature of the expected flows, the optical access available and the information sought. In all three applications, a backscatter geometry had to be used. Laser Doppler velocimetry was employed in the propulsor design. However, since the upper Doppler frequency limit of the correlator was 10 Mz., the high speeds encountered in the turbine and compressor models necessitated the use of laser transit velocimetry. Details of the systems design, the optics and data reduction software are given. Some experimental results of measurements made within cascades and rotating components are presented and their significance concerning the velocimeters used are discussed. The chief conclusions which are drawn from the work are: In many flow configurations of practical interest in gas and steam turbines, transit velocimetry with photon correlation can be used to measure mean velocity to within 1% and turbulence intensity to within 1%. However, in some regions, particularly where the turbulence intensity exceeds approximately 15%, the results are not easy to interpret. Despite the low upper limit to Doppler frequency that can be managed by the 50 nanosecond correlator, its power in processing low-light-level and noisy signals enabled it to be used effectively with a Doppler velocimeter for the measurement of flows within propulsor blading both in a water tunnel and in a wind tunnel. When used with Doppler velocimetry, the inherent averaging mode of operation of the correlator permitted the measurement of mean velocity to within 1%. It also provided a measure of turbulence intensity, which was self consistent to within 2%, although the relationship between this and the standard deviation of velocity was ambiguous. Analysis of the properties of photon correlation in laser velocimetry indicated scope for future work in two directions. Firstly, photon correlation responds to uncertainties arising from particle and velocity biasing in a different way from other signal processors such as burst counters. By carrying out measurements using both types of processor it may be possible to reduce these uncertainties. Secondly, the power of photon correlation in processing low-light-level signals should permit the use of a convenient backscatter arrangement of a reference beam laser Doppler velocimeter to measure the line-of-sight velocity component.
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14

Lapworth, B. L. "Three dimensional elliptic computations for viscous turbomachinery flows." Thesis, Cranfield University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380466.

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15

Sbardella, Luca. "Simulation of unsteady turbomachinery flows for forced response predictions." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341913.

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16

Longo, Joel Joseph. "Unsteady Turbomachinery Flow Simulation With Unstructured Grids Using ANSYS Fluent." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376875053.

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17

Campobasso, Michele Sergio. "Effects of flow instabilities on the linear harmonic analysis of unsteady flow in turbomachinery." Thesis, University of Oxford, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.409723.

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18

Lien, Fue-Sang. "Computational modelling of 3D flow in complex ducts and passages." Thesis, University of Manchester, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.304550.

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19

Bitter, Jamin J. "One-Dimensional Performance Modeling of Centrifugal Flow Vaned Diffusers." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1711.pdf.

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20

Bell, David Lloyd. "Three dimensional unsteady flow for an oscillating turbine blade." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4794/.

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An experimental and computational study, motivated by the need to improve current understanding of blade flutter in turbomachinery and provide 3D test data for the validation of advanced computational methods for the prediction of this aeroelastic phenomenon, is presented. A new, low speed flutter test facility has been developed to facilitate a detailed investigation into the unsteady aerodynamic response of a turbine blade oscillating in a three dimensional bending mode. The facility employs an unusual configuration in which a single turbine blade is mounted in a profiled duct and harmonically driven. At some cost in terms of modelling a realistic turbomachinery configuration, this offers an important benefit of clearly defined boundary conditions, which has proved troublesome in previous work performed in oscillating cascade experiments. Detailed measurement of the unsteady blade surface pressure response is enabled through the use of externally mounted pressure transducers, and an examination of the techniques adopted and experimental error indicate a good level of accuracy and repeatability to be attained in the measurement of unsteady pressure. A detailed set of steady flow and unsteady pressure measurements, obtained from five spanwise sections of tappings between 10% and 90% span, are presented for a range of reduced frequency. The steady flow measurements demonstrate a predominant two-dimensional steady flow, whilst the blade surface unsteady pressure measurements reveal a consistent three dimensional behaviour of the unsteady aerodynamics. This is most especially evident in the measured amplitude of blade surface unsteady pressure which is largely insensitive to the local bending amplitude. An experimental assessment of linearity also indicates a linear behaviour of the unsteady aerodynamic response of the oscillating turbine blade. These measurements provide the first three dimensional test data of their kind, which may be exploited towards the validation of advanced flutter prediction methods. A three dimensional time-marching Euler method for the prediction of unsteady flows around oscillating turbomachinery blades is described along with the modifications required for simulation of the experimental test configuration. Computationalsolutions obtained from this method, which are the first to be supported by 3D test data, are observed to exhibit a consistently high level of agreement with the experimental test data. This clearly demonstrates the ability of the computational method to predict the relevant unsteady aerodynamic phenomenon and indicates the unsteady aerodynamic response to be largely governed by inviscid flow mechanisms. Additional solutions, obtained from a quasi-3D version of the computational method, highlight the strong three dimensional behaviour of the unsteady aerodynamics and demonstrate the apparent inadequacies of the conventional quasi-3D strip methodology. A further experimental investigation was performed in order to make a preliminary assessment of the previously unknown influence of tip leakage flow on the unsteady aerodynamic response of oscillating turbomachinery blades. This was achievedthrough the acquisition of a comprehensive set of steady flow and unsteady pressure measurements at three different settings of tip clearance. The steady flow measurements indicate a characteristic behaviour of the tip leakage flow throughout the range of tip clearance examined, thereby demonstrating that despite the unusual configuration, the test facility provides a suitable vehicle for the investigation undertaken. The unsteady pressure data show the blade surface unsteady pressure response between 10% and 90% span to be largely unaffected by the variation in tip clearance. Although close examination of the unsteady pressure measurements reveal subtle trends in the first harmonic pressure response at 90% span, which are observed to coincide with localised regions where the tip leakage flow has a discernible impact on the steady flow blade loading characteristic. Finally, some recommendations for further work are proposed
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21

Tourlidakis, A. "Numerical modelling of viscous turbomachinery flows with a pressure correction method." Thesis, Cranfield University, 1992. http://hdl.handle.net/1826/3997.

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A fully elliptic computational method for the analysis of steady viscous flow in high speed subsonic centrifugal compressor impellers with tip leakage, is presented. A generalised curvilinear, non-orthogonal grid is utilised and the timeaveraged Navier-Stokes equations are transformed and expressed in a fully conservative form. The discretisation of the governing equations is performed through finite volume integration. The solution procedure employs a non-staggered variable arrangement and a SIMPLE based method for coupling the velocity and pressure fields. The turbulence effects are simulated with the use of the k-e model, modified to account for rotation and streamline curvature, and the near-wall viscous phenomena are modelled through the wall function method. The numerical model is implemented for the flow prediction in a series of two and three dimensional test cases. Incompressible flow predictions in twodimensional cascades and three-dimensional ducting systems with different geometrical features and inlet conditions are initially performed and the numerical results are compared against available experimental data. The final objective of the present study is achieved through the comparative study of the predictions obtained against the results of Eckardt's experimental investigation of the viscous compressible flow in a high speed radial impeller operating at design condition and in a backswept impeller at design and off-design conditions. In addition, the flow is simulated in the passages of the Rolls Royce GEM impeller which was tested at Cranfield at design and off-design flow rates. A jet/wake pattern was discerned in all the simulated centrifugal compressor cases and a good overall agreement was achieved with the measured wake formation and development; and, encouraging results were obtained on the evolution of the secondary flows. The tip leakage effects influenced the loss distribution, the size and the location of the wake flow pattern at the rotor exit. The effects of the flow mass rate on the detailed flow pattern and on the compressor performance have been well represented. In certain cases, the quality of the present predictions is an improvement over that obtained by other "state-of-the-art" Navier-Stokes solvers. In conclusion, the developed finite volume flow model has captured a large number of complex flow phenomena encountered in the tested impellers and is expected to provide a useful aerodynamic analysis tool for stationary or rotating, axial or radial turbomachinery components.
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22

Kilfoil, Alistair S. R. "Modelling of buoyant flow and heat transfer for turbomachinery rotating disc cavities." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/1028/.

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In the design of a gas turbine engine it is important to have a good prediction ofthe temperature distribution for components ofthe engine. This research work looks at the method ofpredicting air and metal temperatures of the lIP compressor disc drum. It is a common practice to supply cooling air for the turbine disc and blades by passing the air axially between the bores of adjacent discs in the lIP compressor. Some ofthe central axial throughflow is known to enter the compressor interdisc cavities and a parasitic temperature rise occurs in the throughflow air as a result ofthe convective heat transfer. It is important that the heat transfer mechanism within a compressor interdisc cavity is understood, as the engine designer needs to know the temperature ofthe cooling air and the disc temperatures in order to predict the stress and the life of the compressor, and also to predict the seal and blade tip running clearances.In this thesis, computational fluid dynamics (CFD) is used to study the flow and heat mechanism experienced by a gas turbine lIP compressor rotor. A review ofprevious research work and knowledge in the field of rotational buoyancy-driven flow has shown that the flow within the compressor inter-disc cavities is highly three-dimensional and time dependent in nature. Two approaches in the numerical modelling ofthe flow can be considered; one is to use CFD as a tool to model a single inter-disc cavity with axial throughflow in full three dimensions with unsteady flow. Using this approach requires a huge amount ofcomputational memory and time to run the CFD models. A second approach is to break down this complex flow process into separate physical mechanisms and introduce approximate but computationally efficient models for these processes. The second approach has been taken in this thesis, with the aim ofproducing a method that can be incorporated into current design practice. Two underlying flow mechanisms may be identified for this complex flow; the first associated with the flow within the inter-disc cavities and the second associated with the axial throughflow under the compressor disc bores.
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23

Micklow, Gerald J. "Turbomachinery cascade and wake calculation for two-dimensional compressible laminar and turbulent flow." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54244.

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A method is presented for the efficient analytical prediction of the two dimensional laminar or turbulent compressor or turbine cascade blade-to-blade flow field and wake. The scheme utilizes a viscous-inviscid interaction routine combining a two-dimensional full potential cascade flow solver with a two-dimensional compressible boundary layer analysis. The boundary layer analysis can compute in the direct mode with pressure gradient specified or in the inverse mode with "boundary layer mass flux" specified. When calculating with the inverse mode, flow separation can be handled easily. Turbulent flow is treated using an algebraic eddy viscosity model with the modified Levy—Lees transformation applied to capture the growth of laminar and turbulent boundary layers. The boundary layer solution is fully implicit and formally second order accurate. The viscous inviscid coupling is performed utilizing thin airfoil theory. Numerical solutions are presented for several numerical test cases and compared with published test data.
Ph. D.
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24

Herrick, Gregory Paul. "Facilitating higher-fidelity simulations of axial compressor instability and other turbomachinery flow conditions." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-04042008-154030.

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25

Yan, Jin. "The effect of end wall profiling on secondary flow in nozzle guide vanes." Thesis, Durham University, 1999. http://etheses.dur.ac.uk/4312/.

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This thesis presents detailed investigations of the effect of end wall profiling on the secondary flow in a large scale, linear cascade with nozzle guide vanes. The purpose of this project is to look into the secondary flow structure in the linear cascade and the influence of the shaped end wall on the secondary flow. By applying the non-axisymmetric end wall, the secondary flow is reduced compared to the flat end wall data. The yaw angle variation at the exit of the blade passage is reduced. The cascade was designed according to the nozzle guide vane from ALSTOM Energy Ltd. It was manufactured and connected to the low speed wind tunnel in the Thermo- Fluids Lab in Durham. The data acquisition system was designed and commissioned. Five hole probes were designed and calibrated according to the cascade test condition. The flow field with the flat end wall in the cascade was investigated using five hole probes through different traverse slots. Flow visualisations were conducted as well. The secondary flow structure and the loss development in the cascade are understood. Transitional trips were put on the blade surfaces and their effects on the secondary flow were observed. The CFD code was modified to fit the cascade case. It was validated against the Durham standard case and the flat end wall results. Different numerical schemes and turbulence models were evaluated. Different shaped end walls were systematically tested by the CFD code. The best end wall profile was selected and manufactured. It was then tested in the cascade. Detailed investigations by five hole probes, flow visualisation and wall static pressure measurements were conducted. The results were compared to the flat end wall results and the CFD prediction. The secondary flow and the total pressure loss were reduced. The test data in the cascade will supply the evidence and data for the real turbine design. The chosen end wall profile will hopefully be tested in a test turbine.
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26

Giuliani, James Edward. "Jet Engine Fan Response to Inlet Distortions Generated by Ingesting Boundary Layer Flow." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1468564279.

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27

Halbe, Chaitanya Vishwajit. "Effects of Two-Phase Flow in a Multistage Centrifugal Compressor." Diss., Virginia Tech, 2016. http://hdl.handle.net/10919/73305.

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The performance of a vapor compression system is known to be affected by the ingestion of liquid droplets in the compressor. In these multiphase flows, the liquid and the vapor phase are tightly coupled. Therefore the interphase heat, mass and momentum transfer as well as droplet dynamics including droplet breakup and droplet-wall interactions play a vital role in governing these flows. Only thermodynamic analyses or two-dimensional mean-line calculations are not sufficient to gain an in-depth understanding of the complex multiphase flow field within the compressor. The objective of this research was to extend the current understanding of the operation of a multistage centrifugal compressor under two-phase flow conditions, by performing three-dimensional computational analysis. In this work, two-phase flow of a single constituent (refrigerant R134a) through a two-stage, in-line centrifugal compressor was analyzed using CFD. The CFD model accounted for real gas behavior of the vapor phase. Novel user defined routines were implemented to ensure accurate calculations of interphase heat, mass and momentum transfer terms and to model droplet impact on the compressor surfaces. An erosion model was developed and implemented to locate the erosion "hot spots" and to estimate the amount of material eroded. To understand the effects of increasing liquid carryover, the mass flow rate of the liquid phase was increased from 1% to 5% of the vapor mass flow rate. The influence of droplet size on the compressor performance was assessed by varying the droplet diameter at the inlet from 100 microns to 400 microns. The results of the two-phase flow simulations were compared with the simulation involving only the vapor phase. Liquid carryover altered the flow field within the compressor, and as a result, both impellers were observed to operate at off-design conditions. This effect was more pronounced for the second impeller. The overall effects of liquid carryover were detrimental to the compressor performance. The erosion calculations showed maximum erosion potential on the blade and shroud of the first impeller. The results from this investigation provided new and useful information that can be used to support improved design solutions.
Ph. D.
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28

Fordham, Guangli Chen. "A numerical and experimental investigation of two-dimensional compressible turbine tip gap flow." Thesis, University of Cambridge, 1994. https://www.repository.cam.ac.uk/handle/1810/251713.

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29

Sun, Tianrui. "Improved Flutter Prediction for Turbomachinery Blades with Tip Clearance Flows." Licentiate thesis, KTH, Energiteknik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-233770.

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Recent design trends in steam turbines strive for high aerodynamic loading and high aspect ratio to meet the demand of higher efficiency. These design trends together with the low structural frequency in last stage steam turbines increase the susceptibility of the turbine blades to flutter. Flutter is the self-excited and self-sustained aeroelastic instability phenomenon, which can result in rapid growth of blade vibration amplitude and eventually blade failure in a short period of time unless adequately damped. To prevent the occurrences of flutter before the operation of new steam turbines, a compromise between aeroelastic stability and stage efficiency has to be made in the steam turbine design process. Due to the high uncertainty in present flutter prediction methods, engineers use large safety margins in predicting flutter which can rule out designs with higher efficiency. The ability to predict flutter more accurately will allow engineers to push the design envelope with greater confidence and possibly create more efficient steam turbines. The present work aims to investigate the influence of tip clearance flow on the prediction of steam turbine flutter characteristics. Tip clearance flow effect is one of the critical factors in flutter analysis for the majority of aerodynamic work is done near the blade tip. Analysis of the impact of tip clearance flow on steam turbine flutter characteristics is therefore needed to formulate a more accurate aeroelastic stability prediction method in the design phase.Besides the tip leakage vortex, the induced vortices in the tip clearance flow can also influence blade flutter characteristics. However, the spatial distribution of the induced vortices cannot be resolved by URANS method for the limitation of turbulence models. The Detached-Eddy Simulation (DES) calculation is thus applied on a realistic-scale last stage steam turbine model to analyze the structure of induced vortices in the tip region. The influence of the tip leakage vortex and the induced vortices on flutter prediction are analyzed separately. The KTH Steam Turbine Flutter Test Case is used in the flutter analysis as a typical realistic-scale last stage steam turbine model. The energy method based on 3D unsteady CFD calculation is applied in the flutter analysis. Two CFD solvers, an in-house code LUFT and a commercial software ANSYS CFX, are used in the flutter analysis as verification of each other. The influence of tip leakage vortex on the steam turbine flutter prediction is analyzed by comparing the aeroelastic stability of two models: one with the tip gap and the other without the tip gap. Comparison between the flutter characteristics predicted by URANS and DES approaches is analyzed to investigate the influence of the induced vortices on blade flutter characteristics. The multiple induced vortices and their relative rotation around the tip leakage vortex in the KTH Steam Turbine Flutter Test Case are resolved by DES but not by URANS simulations. Both tip leakage vortex and induced vortices have an influence on blade loading on the rear half of the suction side near the blade tip. The flutter analysis results suggest that the tip clearance flow has a significant influence on blade aerodynamic damping at the least stable interblade phase angle (IBPA), while its influence on the overall shape of the damping curve is minor. At the least stable IBPA, the tip leakage vortex shows a stabilization effect on rotor aeroelastic stabilities while the induced vortices show a destabilization effect on it. Meanwhile, a non-linear unsteady flow behavior is observed due to the streamwise motion of induced vortices during blade oscillation, which phenomenon is only resolved in DES results.
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30

Sleiman, Mohamad. "Simulation of 3-D viscous compressible flow in multistage turbomachinery by finite element methods." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/NQ39027.pdf.

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31

Small, Matthew David. "Frequency Domain Methods for Predicting the Transport of Non-Uniform Flow Through Turbomachinery Compressors." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/32293.

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A new method to predict the transport of non-uniform total pressure distributions through an axial flow compressor is presented. The method relies on frequency-domain transformations of total pressure distortion patterns, and the use of digital filter techniques to capture the effect of a blade row on the total pressure distortion. Compressor characteristics, described by a frequency response function, are obtained from experimental data and are related to fundamental blade row flow phenomena. When excited by a total pressure distribution with unknown response, the blade rowâ s frequency response function can serve to predict the downstream total pressure profile. This work covers the application of frequency response functions for turbomachinery blade rows, and includes the development of a process that improves the capability of linear response functions to model nonlinear flow behavior. The process is empirically based and relies on several original correlation parameters. Developed frequency domain modeling methods are applied to a rotor of modern design with promising results.
Master of Science
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32

GUIDOTTI, EMANUELE. "Analysis of the Unsteady Flow in an Aspirated Counter-Rotating Compressor Using the Nonlinear Harmonic Balance Method." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1218690946.

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33

Fitzgerald, Kevin D. "Examination of flow around second-generation controlled diffusion compressor blades in cascade at stall." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 2004. http://library.nps.navy.mil/uhtbin/hyperion/04Jun%5FFitzgerald.pdf.

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34

Albusaidi, Waleed. "Techno-economic assessment of radial turbomachinery in process gas applications." Thesis, Cranfield University, 2016. http://dspace.lib.cranfield.ac.uk/handle/1826/9872.

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This research aims to assess the causes of inefficient and unstable operation of centrifugal compressors and turboexpanders in process gas applications in order to provide a solution for performance restoration and enhancement. It encompasses thermodynamic and flow evaluations to examine the efficiency and operating range improvement options of new units. Besides, this work is complemented by a technoeconomic analysis to provide a rounded outcome from these studies. In order to achieve the desired objectives, a novel integrated approach has been developed to assess the design and performance of multi-stage centrifugal compressors. The proposed systematic methodology involves five basic elements including evaluation of compressor selection, compressor sizing and casing structure, performance prediction at the design and off-design conditions, modelling of efficiency and head deterioration causes; and stage design evaluation. This will contribute towards evaluating the geometrical parameters of the new units’ designs at the early preliminary design phase, and thus, will be useful to identify the options for efficiency and operating range enhancements. For installed units, this approach can be implemented to assess the cause of inefficient and unstable operation by assessing the available operation data. A method was developed to predict the performance curve of multi-stage centrifugal compressor based on a stage stacking technique. This approach considers the advantages of Lüdtke and Casey-Robinson methods with an incorporation of a methodology for compressor selection and sizing to generate more accurate results. To emphasize the validity of the developed model, it has been evaluated for both low and high flow coefficient applications. The obtained results show a significant improvement in the estimated efficiency, pressure ratio, shaft power and operating range as compared with the existing methods. The centrifugal compressor is designed to run under various operating conditions and different gas compositions with the primary objective of high efficiency and reliability. Therefore, a new iterative method has been developed to predict the equivalent compressor performance at off-design conditions. This technique uses the performance parameters at design conditions as a reference point to derive the corresponding performance characteristics at numerous suction conditions with less dependency on the geometrical features. Through a case study on a gas transport centrifugal compressor, it was found that the developed approach can be applied for design evaluation on the expected variation of working conditions, and for the operation diagnosis of installed units as well. Furthermore, a parametric study has been conducted to investigate the effect of gas properties on the stage efficiency, surge margin, and compressor structure. The obtained results support the need for considering the gas properties variation when the off-design performance is derived. To evaluate the impact of internal blockage on the performance parameters, this study proposed an approach to model the effect of non-reactive deposits, which has been qualified using four operation cases and the obtained results are compared with the internal inspection findings from the stage overhauling process. This also covers the influential aspects of flow blockage on the technical and economic values. Since the main challenge here is to analyze the process gas composition in real time, the influences of the non-reactive deposits have been compared with the effect of the unanticipated gas composition change. Subsequently, it has turned out that the pressureratio parameter is not enough to assess the possibility of flow blockage and unexpected gas properties change. Moreover, it was observed that the stage discharge pressure was more sensitive to the fouled aftercooler comparing with suction and internal blockage. However, the effect of contaminated aftercooler on the surge point and discharge pressure and temperature of the upstream stage was found greater than its impact on the shaft power. Thus, a substantial surge margin reduction was detected when the first stage was operating with a fouled aftercooler comparing with the measured reduction as a result of unanticipated gas properties change. Furthermore, a larger pressure ratio drop was measured in the case of liquid carryover which revealed a more significant impact of the two phases densities difference comparing with the gas volume fraction (GVF) effect. The possibility of hydrate formation has been assessed using hydrate formation temperature (HFT) criteria. Additionally, this research highlights a number of challenges facing the selection of typical centrifugal stage design by assessing the contribution of design characteristics on the operating efficiency and stable flow range. Besides, an empirical-based-model was established to select the optimum impeller and diffuser configurations in order to make a compromise decision based on technical and economic perspective. It was concluded that there is no absolute answer to the question of optimum rotor and stator configuration. The preliminary aerothermodynamic evaluation exposed that the selection of the optimum impeller structure is governed by several variables: stage efficiency, pressure loss coefficient, manufacturing cost, required power cost, resonance frequency and stable operating range. Hence, an evaluation is required to compromise between these parameters to ensure better performance. Furthermore, it was argued throughout this study that the decision-making process of the typical stage geometrical features has to be based upon the long-term economic performance optimization. Thus, for higher long-term economic performance, it is not sufficient to select the characteristics of the impeller and diffuser geometry based on the low manufacturing cost or efficiency improvement criterion only. For turboexpanders, a simple and low cost tool has been developed to determine the optimum turboexpander characteristics by analysing the generated design alternatives. This approach was used in designing a turboexpander for hydrocarbon liquefaction process. Moreover, since the turboexpanders are expected to run continuously at severe gas conditions, the performance of the selected turboexpander was evaluated at different inlet flow rates and gas temperatures. It has turned out that designing a turboexpander with the maximum isentropic efficiency is not always possible due to the limitations of the aerodynamic parameters for each component. Therefore, it is necessary to assess the stage geometrical features prior the construction process to compromise between the high capital cost and the high energetic efficiency.
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35

Hariharan, Vivek. "TRANSITIONAL FLOW PREDICTION OF A COMPRESSOR AIRFOIL." UKnowledge, 2010. http://uknowledge.uky.edu/gradschool_theses/44.

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The steady flow aerodynamics of a cascade of compressor airfoils is computed using a two-dimensional thin layer Navier-Stokes flow solver. The Dhawan and Narasimha transition model and Mayle‟s transition length model were implemented in this flow solver so that transition from laminar to turbulent flow could be included in the computations. A method to speed up the convergence of the fully turbulent calculations has been introduced. In addition, the effect of turbulence production formulations and including streamline curvature correction in the Spalart-Allmaras turbulence model on the transition calculations is studied. These transitional calculations are correlated with the low and high incidence angle experimental data from the NASA-GRC Transonic Flutter Cascade. Including the transitional flow showed a trendwise improvement in the correlation of the computational predictions with the pressure distribution experimental data at the high incidence angle condition where a large separation bubble existed in the leading edge region of the suction surface.
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36

Falk, Matilda, and Sabina Hedkrok. "Coordination of the information and material flow of lego products - A case study at Siemens Industrial Turbomachinery AB." Thesis, Linköpings universitet, Kommunikations- och transportsystem, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-122918.

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Studien betraktar informations- och materialflödet för legomaterial på Siemens Industrial Turbomachinery AB i Finspång. Det studerade problemet gäller att det finns en dålig uppfattning bland de anställda om hur flödet och arbetet med lego ser ut, samt dålig kommunikation mellan de inblandade avdelningarna. Genom intervjuer med ansvariga för legomaterialsamt granskning av tidigare dokument har legoflödet kunnat beskrivas. Problematiken på företaget har studerats utifrån teori kring processer och flöden samt kommunikation, integration och koordinering Rapporten presenterar en samordnad bild över arbetet med legomaterial genom en kartläggning med tillhörande flödesschema över informations- och materialflödet för lego inom företaget. I studien har problem med koordination och samarbetet mellan de inblandade avdelningarna identifierats. Rapporten följs upp med förslag på åtgärder och vidare arbete för att lösa problemen.
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37

Bloxham, Matthew Jon. "A Global Approach to Turbomachinery Flow Control: Loss Reduction using Endwall Suction and Midspan Vortex Generator Jet Blowing." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1267472116.

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38

Wan, Bo [Verfasser]. "Development of Numerical Algorithm Based on a Modified Equation of Fluid Motion with Application to Turbomachinery Flow / Bo Wan." Aachen : Shaker, 2012. http://d-nb.info/1052408478/34.

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39

Gagne, Anton. "Effects of Asymmetry and Other Non-Standard Excitations on Structural Dynamic Forced Response Analysis of Turbomachinery Flow-Path Components." Thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-154623.

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A recent paper explored a potential deficiency in the single frequency harmonic response structural dynamic analysis approach typically used to assess a resonant condition in turbomachinery flow path components. This deficiency is prevalent in supersonic flow conditions when non-adjacent stages are present. The previous investigation demonstrated other excitation sources present in complex or supersonic flows could be missed using the typical analysis approach, in some cases leading to large under-prediction of structural response when compared with a baseline transient analysis. This paper presents the results of a follow on study, in which the inclusion of these effects in dynamic analyses is investigated. A representative rotor was created and analyzed for forced response characteristics when individual and combined unsteady content was present. A simple shell and beam 2D model was used to study the forced response behavior using transient and harmonic analyses. The results showed a significant contribution from non-integer forcing as well as from certain integer order forcing. A 3D model was also created for future analysis but did not display the sideband characteristics similar to flow seen in the previous investigation.
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40

Naber, Logan A. "High Pressure Ratio Compressor Performance Design and Optimization." University of Cincinnati / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1626357000628287.

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41

Zetterström, Filippa, and Niklas Ek. "Lead time analysis from order to delivery : A study of lead time in the material flow and the information flow for the aftermarket at Siemens Industrial Turbomachinery AB." Thesis, Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119670.

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Siemens Industrial Turbomachinery AB (SIT) is a company that produces and delivers medium sized industrial gas turbines to customers all over the world and is located in Finspång. The Service section of SIT handles the aftermarket of turbines with both planned and unplanned inspections/repairs. SIT-Service experience that their lead time to customers is too long and a yearly survey with customers confirmed this. Service strives for a higher customer service and since the company suspect that internal processes have safety time built into can time quickly build up. Service has different service lines depending on what kind of maintenance needed and if planned/unplanned. Different options in a combination with several departments involved in these big projects make the flow hard to visualize and makes it complex.This report has studied how SIT-Service can enable a lead time reduction from order to delivery where the flow for Parts was chosen to be mapped and analyzed for one of the service lines. This orientation of the study was partly based on directions from the company and partly delimitations by the writers of the report. Directions from the company were for example to investigate a standard scope and to visualize the flow by mapping it, all with a focus on lead time. Delimitations developed to exclude sales and transportations as well as to only investigate one turbine type and one service line. To be able to follow the flow was a decision made to investigate the flow for Parts.The study has mapped times and activities in the Parts flow from received purchase order (PO) from customer to when parts are ready to leave SIT Finspång. This mapping includes several departments and several transactions in the ERP-system, activities, tasks, queues and uncertainties. The mapping investigated how the lead time was built up by the system and one angle of the mapping was to investigate if the times in the system were consistent with the matching times in reality. To be able to suggest any changes in the Parts flow regarding lead time, the mapping was classified based on value-adding/non-value-adding, wastes, critical chain and bottlenecks. This was followed by a use of different principles in how to enable lead time reduction. These principles were: elimination, simplification, parallelization and a combination of critical chain and bottlenecks.The results and conclusions based on the two analysis parts have been divided into two parts where suggestions in the first one are believed to have a larger impact on the total lead time. This part consists of five big areas of time with several suggestions, from concrete to more general. One of the most important areas is that SIT needs to improve how the company uses the Planned delivery time; to standardize and to make sure that it is used in the same way by all involved which could eliminate unnecessary times built in. Another important area is that the Goods receiving process time could be reduced for a majority of material in the ERP-system since this differs today even if material is handled the same in reality. The second part consisting of 14 smaller areas of suggestions are believed to have a smaller impact on the total lead time but are still considered to be important to implement. All suggestions have an order of implementation which recommends what should be done first for SIT-Service. If the suggestions are implemented is it believed that SIT-Service can shorten the lead time in the Parts flow and also to get a more efficient organization.
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42

LIST, MICHAEL GREGORY. "QUARTER ANNULUS SIMULATIONS OF BLADE ROW INTERACTION AT SEVERAL GAPS AND DISCUSSION OF LOW PHYSICS." University of Cincinnati / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1187025480.

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43

Sanz, Luengo Antonio. "Experimental Investigation of the Influence of Local Flow Features on the Aerodynamic Damping of an Oscillating Blade Row." Licentiate thesis, KTH, Kraft- och värmeteknologi, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-145179.

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The general trend of efficiency increase, weight and noise reduction has derived in the design of more slender, loaded, and 3D shaped blades. This has a significant impact on the stability of fan, and low pressure turbine blades, which are more prone to aeroelastic phenomena such as flutter. The flutter phenomenon is a self-excited, self-sustained unstable vibration produced by the interaction of flow and structure. These working conditions will induce either blade overload, or High Cycle Fatigue (HCF) produced by Limited Cycle Oscillation (LCO). The main objectives of the present work are on the investigation of the aeroelastic properties of a high-lift low-pressure in the light of the local flow features present in such profiles, in nominal and extreme off-design conditions both in high and low subsonic Mach number, for three dif-ferent rigid body modes. In addition, the validity of the linearity assump-tion of the influence coefficient technique has also been investigated, in order to expand the understanding of the physical limits of this assumption. This work has been designed as experimental investigation in the influence coefficient domain focused on a high-lift low-pressure turbine designed by ITP within the framework of the European FP7 project FU-TURE. These experiments have been carried out in the Aeroelastic test rig (AETR), at KTH Stockholm, which consist of an instrumented annular sector cascade with a single oscillating blade. The results acquired have been supported by numerical results provided by a non-propietary commercial software package (ANSYS CFX). The results suggest that the typical three-dimensional effects associated secondary flow features and tip leakage flows have a significant influence on the aeroelastic performance and the cascade stability. However the major influence appears as a consequence of the separation surface on the pressure side which appears at extreme off-design operating conditions. The contribution to stability of this local feature depend on the oscillation mode showing for the axial and torsion mode a neutral stability contribution, which is directly associated with the geometrical properties of the cascade. However, on the circumferential mode this separation surface has a stabilizing effect much more independent of the blade geometry. The study of the linearity assumption of the influence coefficient domain has revealed, that an apparent linear relation between the integrated unsteady response and the vibrational amplitude, does not necessary imply that the local unsteady response is linear with respect to the oscillation amplitude. The results also suggest that the validity of the linearity as-sumption is more sensitive to high oscillation amplitudes at high Mach conditions.

QC 20140609

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44

Johnson, Jesse Scott. "The Effects of Freestream Turbulence on Serpentine Diffuser Distortion Patterns." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3500.

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Serpentine diffusers have become a common feature in modern aircraft as they allow for certain benefits that are impossible with a traditional linear configuration. With the benefits, however, come certain disadvantages, namely flow distortions that reduce engine efficiency and decrease engine surge stability margins. These distortions are now being researched comprehensively to determine solutions for mitigating the adverse effects associated with them. This study investigates how varying the freestream turbulence intensity of the flow entering a serpentine diffuser affects the distortion patterns that are produced by the diffuser. Experiments were performed with a model serpentine diffuser on the Annular Cascade Facility of the Air Force Research Laboratory at Wright-Patterson Air Force Base. Hot wire anemometry was used to measure inlet turbulence, while static pressure probes located axially along the upper and lower surface of the model diffuser and total pressure probes located across the aerodynamic interface plane (AIP) were used to measure the distortion patterns of the flow passing through the diffuser. Varying levels of inlet freestream turbulence, ranging from 0 to 4%, were generated using square and round bar turbulence screens in three distinct test configurations. Axial static pressure measurements indicate that increasing turbulence slightly affects flow separation development downstream of the second turn. This effect is also seen at the AIP where the total pressure recovery increases with increasing level of inlet turbulence in the region of flow separation at the upper surface. The total pressure recovery along the lower surface is also seen to be increased with higher inlet turbulence. However, total pressure recovery increase across the entire AIP is almost negligible. Overall, the inlet freestream turbulence has a minor effect on the distortion patterns caused by the serpentine diffuser when compared with proven active inlet flow control methods.
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45

Heberling, Brian. "A Numerical Analysis on the Effects of Self-Excited Tip Flow Unsteadiness and Upstream Blade Row Interactions on the Performance Predictions of a Transonic Compressor." University of Cincinnati / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ucin150479438822623.

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46

Mårtensson, Jonathan. "Method development for investigation of real effects on flow around vanes." Thesis, Linköping University, Applied Thermodynamics and Fluid Mechanics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-57605.

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In the development of turbo machinery components it's desirable to not spend more time than necessary when setting up aero-thermal calculations to investigate uncertainties in the design. This report aims to describe general thoughts used in the development of an ICEM-mesh script and the possible configurations in the script file which enables the user to build mesh-grids with/without clearance gap at the hub and/or shroud for different blade geometries. It also aims to illustrate the performance analysis made on the Vinci LH2 turbine, a next generation upper stage engine to the Ariane 5 rocket, in which the effect of the tip gap size on the efficiency has been studied.

The calculations made have shown good agreement with experimental data. The efficiency loss due to the mixing of fluid where leakage flow passes the tip gap, which results in growth of a strong vortex, and the fluid passing the blade tip, with almost no work extracted from it, has shown a quite linear efficiency dependence depending on the tip gap size.

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47

Green, Brian Richard. "Time-Averaged and Time-Accurate Aerodynamic Effects of Rotor Purge Flow for a Modern, Rotating, High-Pressure Turbine Stage and Low-Pressure Turbine Vane." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1322535026.

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48

Wan, Bo [Verfasser], Friedrich-Karl [Akademischer Betreuer] Benra, and Siavash H. [Akademischer Betreuer] Sohrab. "Development of Numerical Algorithm Based on a Modified Equation of Fluid Motion with Application to Turbomachinery Flow / Bo Wan. Gutachter: Siavash H. Sohrab. Betreuer: Friedrich-Karl Benra." Duisburg, 2012. http://d-nb.info/1027669212/34.

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49

Fletcher, Nathan James. "Design and Implementation of Periodic Unsteadiness Generator for Turbine Secondary Flow Studies." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright1560810428267352.

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50

Newman, Timothy James. "Towards a silent fan : an investigation of low-speed fan aeroacoustics." Thesis, University of Cambridge, 2015. https://www.repository.cam.ac.uk/handle/1810/251318.

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The noise (unwanted sound) from fans of all sizes, operating in close proximity to people, can be a design constraint due to annoyance or, in the worse cases, health damage. Of the total noise, aeroacoustic noise - produced by unsteadiness in the air - often represents a significant source and is intrinsically linked to the aerodynamic features of the flow field. In this work, the aeroacoustics of low-speed fans are investigated using a compact mixed-flow fan as a test case. The low-speed regime is less developed compared to large-scale, high-speed machines and is increasingly relevant to applications such as micro air vehicles, small wind turbines, and other environmental comfort technologies found in buildings or vehicles. The test case fan Reynolds number is of the order of 104 which is a couple of orders lower than those generally found in gas turbines. Its main sources are therefore best identified experimentally in the absence of proven alternative methods. In order to do this, a way of quantifying fan noise is developed in tandem with control of the aerodynamic operating point. Following a study of sources of the significant broadband and tonal noise, a low-order noise prediction scheme is developed and applied to predict tonal noise with reference to Reynolds number effects. The new, duct-based rig and method has several advantages over the existing sound power measurement rig built to the ISO 5136 standard at Dyson. The approach, which makes no assumptions about the relative power of different modes, has resulted in a rig that is much shorter. Unlike the ISO rig, it is capable of accurate narrow-band tone measurements with sources which excite strong non-plane-wave duct modes (as the modal structure of the sound is determined) for the frequencies of interest. Tests have been carried out at different operating points with a range of geometry modifications produced with 3D printing techniques. In terms of tonal sources which particularly impact sound quality, the mixed-flow impeller alone produces tones due to very high sensitivity to inflow distortion of the mean flow (giving unsteady blade loading). This means that the product inlet must be designed very carefully to optimally condition the flow. Periodicity in the impeller outlet flow produces rotor-stator interaction tones even with a number of guide vanes chosen to satisfy the Tyler-Sofrin theory cut-off criteria. This is thought to be due to abrupt radius change after the guide vanes in the rig (while the theory assumes constant radius). In the product, abrupt radius change also occurs. The sensitivity of the broadband level to inflow turbulence was confirmed to be low in the rig, although the in-product inflow appears much less ideal. The main broadband noise source in rig tests is suggested to be impeller self-noise as only small reductions in rotor-stator interaction noise are achieved with far fewer vanes. The low-order modelling scheme to understand the fundamental unsteady loading noise mechanism compares well to experiments for sample rotor-stator interaction tones. The velocity fluctuations which induce this noise, measured experimentally with a 2D hotwire, are shown to increase in intensity as Reynolds number is reduced towards 104. This is due to a higher importance of viscosity which can give boundary layers that are thicker and liable to laminar separation. Surface treatments such as boundary layer trips could be used to prevent such separation and potentially reduce noise. Based on the thesis findings, further tests, simulations and possible design modifications are suggested to understand and reduce the important noise sources.
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