Dissertations / Theses: 'Low pressure turbine material'

1

He, Binyan. "Fatigue crack growth behaviour in a shot peened low pressure steam turbine blade material." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/388077/.

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Williams, Charles P. "Low Pressure Turbine Flow Control with Vortex Generator Jets." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470741489.

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Verona, Claire L. "Stress corrosion cracking of low pressure steam turbine blade and rotor materials." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10165.

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Stress corrosion cracking of a 14 wt% Cr martensitic stainless steel, with commercial names PH-15Cr5Ni, FV520B or X4CrNiCuMo15-5, used for the manufacture of low pressure turbine blades, has been studied with the intention of gaining a better understanding of the processes involved, how they occur and why. Industrially this is very important as stress corrosion cracking is considered to be a delayed failure process, whereby microscopic cracks can potentially propagate through a metal undetected until catastrophic failure occurs. The aim of this work is to establish links between crack length and external factors, such as exposure time, in order to devise a method of dating stress corrosion cracks and therefore predicting their possible occurrence in-service.

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Seumangal, Nicole. "Influence of the heat treatment procedure on the stress corrosion cracking behaviour of low pressure turbine blade material FV566." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/27427.

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Stress corrosion cracking is one of the leading damage mechanisms in low-pressure turbines in the power generation industry; in LP turbine blades it primarily occurs in the last stage blades. The research investigated the influence of tempering temperature on the microstructure, mechanical properties, and stress corrosion cracking properties of 12% chromium FV566 stainless steel, which is used to manufacture LP turbine blades. The standard heat treatment of the steel comprises of austenitising, quenching and double tempering. Austenitising is carried out at 1050°C for one hour - which is sufficiently long to generate a fully austenitic matrix and to dissolve carbon completely. Subsequently, the material is quenched in air. The high level of alloying elements ensures the complete martensitic transformation, with carbon atoms trapped in the matrix and distributed homogeneously. Thereafter, tempering of the material at 580-600°C enhances the ductility and toughness. Tempering replaces the solid solution strengthening of the dissolved carbon with precipitation strengthening by carbides. The final microstructure of the FV566 steel blades is referred to as tempered martensite. van Rooyen showed that for 12% chromium steel tempering at and above 600°C induces passivity of the material against SCC, while tempering of 12% chromium steels at 450-550°C causes sensitisation of the material and the material exhibits intergranular SCC. From such studies, the motivation arises to investigate the impact of heat-treatment parameters - specifically the impact of tempering temperature on the stress corrosion behaviour of the material. The testing methodology comprises heat treatment of FV566 samples at 1050°C for 1 hour, at 350°C for 1 hour, and thereafter tempering for 1 hour at various tempering temperatures. Each stage of heat treatment is followed by air cooling - followed by analysis of the microstructure, mechanical testing and stress corrosion cracking testing of the specimens at the different temper conditions. Stress corrosion testing was divided into two categories. The first set of tests was carried out with U-bend specimens to determine the susceptibility of materials at different heat treatments to SCC, the time taken for SCC to initiate, and the mode of cracking. The second set of tests was conducted to determine the threshold stress intensity, as a function of crack growth rate, for each heat treatment. The SCC failure mechanism observed was intergranular SCC (IGSCC) by anodic dissolution for the 550°C, 560°C, 570°C, 580°C, 590°C, 600°C and 620°C specimens. The material's resistance to SCC improved with increasing tempering temperature. Specimens tempered at 480°C and 550°C were most susceptible to SCC, while specimens tempered at 600°C The material's resistance to SCC improved with increasing tempering temperature. Specimens tempered at 480°C and 550°C were most susceptible to SCC, while specimens tempered at 600°C were immune to SCC in a 4000-hour period. A change in tempering temperature results in a change in the quantity and type of precipitates formed which results in changes in SCC properties of FV566.

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Von, Hagen William J. "Analysis of the L1A, L1M, L2A, and L2F Low-Pressure Turbine Blades Using Large-Eddy Simulation." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1470045392.

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Naicker, Leebashen. "Influence of heat treatment condition on the stress corrosion cracking properties of low pressure turbine blade steel FV520B." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25377.

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Stress corrosion cracking (SCC) is a corrosion phenomenon which continues to plague the power generating industry especially in low pressure (LP) steam turbine blades operating in the phase transition zone. An investigation has therefore been conducted to examine the effect of heat treatment condition on the microstructure, mechanical properties and SCC properties of one such LP turbine blade material, FV520B, used in the steam turbines of coal-fired power stations in South Africa. The three stage heat treatment cycle of the FV520B turbine blades consists of homogenisation at 1020°C for 30 minutes, solution treatment at 790°C for two hours and precipitation hardening at 545°C for six hours. In this study, the precipitation hardening temperature was varied in the range 430-600°C to investigate how this variation would affect the material and SCC properties. Hardness and tensile testing were performed to obtain mechanical properties while the investigative techniques used to characterise the microstructures were light microscopy, dilatometry, X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Stress corrosion susceptibility for the different heat treatment conditions was quantified using U-bend specimens while crack growth rates and threshold stress intensities for SCC (KISCC) were measured using fatigue precracked wedge open loaded (WOL) specimens. Both SCC tests were conducted in a 3.5% NaCl environment maintained at 90°C. XRD results revealed the presence of reverted austenite in the higher tempered specimens due to the precipitation hardening temperature being close to the Ac1 temperature for the material. The presence of reverted austenite was shown to adversely affect mechanical strength and hardness which decreased with increasing precipitation hardening temperature. Light and electron microscopy (SEM and TEM) revealed the presence of Cr-rich precipitates along the prior austenite grain boundaries in all tested heat treatment conditions. The propensity, quantity and size of the Cr-rich precipitates increased as the specimen temper temperature increased. SCC susceptibility was shown to be dependent upon yield strength and decreased as precipitation hardening temperature increased with specimens in the overaged condition showing no cracking after more than 5000 hours in the test environment. WOL testing only produced cracking in the three highest strength specimens after 2000 hours. Crack growth rates and threshold stress intensities were found to be dependent on yield strength and decreased with increasing precipitation hardening temperature. Analysis of fracture surfaces revealed crack propagation along prior austenite grain boundaries in all test heat treatment conditions indicating intergranular stress corrosion cracking (IGSCC) as the dominant cracking mechanism.

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Gompertz, Kyle Adler. "Separation Flow Control with Vortex Generator Jets Employed in an Aft-Loaded Low-Pressure Turbine Cascade with Simulated Upstream Wakes." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243990496.

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TERNER, MATHIEU. "Innovative materials for high temperature structural applications: 3rd Generation γ-TiAl fabricated by Electron Beam Melting." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2527509.

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In the aeronautics industry, the propulsion systems stand among the most advanced and critical components. Over the last 50 years, gas turbine aeroengines were subjected to intensive research to increase efficiency and reduce weight, noise and harmful emissions. Together with design optimization, breakthrough in materials science for structural applications triggered the development of the most advanced gas turbine engines. For low temperatures, basically ahead of the combustion section, lightweight Ti alloys are preferred for their good mechanical properties. For high temperatures instead, Ni-based superalloys exhibit outstanding properties up to very high temperatures despite a rather high material’s density. Research have focused on enhancing to the maximum the potential of materials in gas turbine engines. According to the application, the components experience various mechanical and environmental constraints. Special designs, manufacturing process, material compositions and protective coatings have been developed to push the limits of advanced materials. Nowadays, the attention is focused on innovative materials to replace the existing Ti and Ni based alloys leading to substantial benefits. Light weight composite materials in particular were found very attractive to replace some components’ Ti alloys. At higher temperatures, it is of great interest to replace Ni-based superalloys by materials with lower density and/or higher temperatures applications, which in turn would lead to substantial weight reduction and increase efficiency. At the highest temperatures range, in particular in the combustion chamber and high pressure turbine sections, ceramic based materials offer promising balance of properties. Research are dedicated to overcome the drawbacks of ceramics for such structural applications, and in particular their brittle fracture behavior, by addition of reinforcing fibers. At lower temperatures range, TiAl based intermetallics emerged as very promising materials at half the density of Ni-based superalloys. Significant weight reduction could be achieved by the introduction of TiAl based alloys for rotating components of the compressor and low pressure turbine. 2nd generation γ-TiAl alloys were lately introduced in GE’s GEnx and CFM’s LEAP engines. The present work concerns the fabrication by the additive manufacturing technique Electron Beam Melting of 3rd generation γ-TiAl alloys for high temperatures application in gas turbine aeroengines. EBM, building parts layer by layer according to CAD, offers many advantages compared to other manufacturing processes like casting and forging. Reported by Avio, 2nd generation γ-TiAl alloys have been successfully fabricated by EBM. To increase the material’s potential, the production of 3rd generation γ-TiAl alloys Ti-(45-46)Al-2Cr-8Nb was therefore studied. The optimization of the EBM parameters led to high homogeneity and very low post-processing residual porosity ≤ 1%. The fine equiaxed microstructure after EBM could be tailored towards the desired mechanical properties by simple heat treatment, from equiaxed to duplex to fully lamellar. In particular, a duplex microstructure composed by about 80 % lamellar grains pinned at grain boundaries by fine equiaxed grains was obtained after heat treatment slightly over the α transus temperature. The study showed that addition of a higher amount of Nb significantly increased the oxidation resistance of the material, thus increasing the application temperature range of these γ-TiAl alloys.

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Flage, Alexander Paul. "Computational Investigation of Low-Pressure Turbine Aerodynamics." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27915.

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The design of today?s gas turbine engines is heavily reliant on accurate computational fluid flow models. Creating prototype designs is far more expensive than modeling the design on a computer; however, current turbulence and transitional flow models are not always accurate. Several turbulence and transition models were validated at North Dakota State University by analyzing the flow through a low pressure turbine of a gas turbine engine. Experimental data for these low pressure turbines was provided by the University of North Dakota. Two separate airfoil geometries are analyzed in this study. The first geometry is a first stage flow vane, and the second geometry is an incidence angle tolerant turbine blade. Pressure and heat transfer data were compared between computations and experiments on the turbine blade surfaces. Simulations were conducted with varying Reynolds numbers, Mach numbers, and free stream turbulence intensities and were then compared with experiments.

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Ssebabi, Brian. "Experimental evaluation of a low temperature and low pressure turbine." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86563.

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Thesis (MEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The potential benefits from saving energy have driven most industrial processing facilities to pay more attention to reducing energy wastage. Because the industrial sector is the largest user of electricity in South Africa (37.7% of the generated electricity capacity), the application of waste heat recovery and utilisation (WHR&U) systems in this sector could lead to significant energy savings, a reduction in production costs and an increase in the efficiency of industrial processes. Turbines are critical components of WHR&U systems, and the choice of an efficient and low cost turbine is crucial for their successful implementation. The aim of this thesis project is therefore to validate the use of a turbine for application in a low grade energy WHR&U system. An experimental turbine kit (Infinity Turbine ITmini) was acquired, assembled and tested in a specially designed and built air test bench. The test data was used to characterise the turbine for low temperature (less than 120 Celsius) and pressure (less than 10 bar) conditions. A radial inflow turbine rotor was designed, manufactured and then tested with the same test bench, and its performance characteristics determined. In comparison with the ITmini rotor, the as-designed and manufactured rotor achieved a marginally better performance for the same test pressure ratio range. The as-designed turbine rotor performance characteristics for air were then used to scale the turbine for a refrigerant-123 application. Future work should entail integrating the turbine with a WHR&U system, and experimentally determining the system’s performance characteristics.
AFRIKAANSE OPSOMMING: Die potensiële voordele wat gepaard gaan met energiebesparing het die fokus van industrie laat val op die bekamping van energievermorsing. Die industriële sektor is die grootse verbruiker van elektrisiteit in Suid-Afrika (37.7% van die totale gegenereerde kapasiteit). Energiebesparing in die sektor deur die toepassing van afval-energie-herwinning en benutting (AEH&B) sisteme kan lei tot drastiese vermindering van energievermorsing, ‘n afname in produksie koste en ‘n toename in die doeltreffendheid van industriële prosesse. Turbines is kritiese komponente in AEH&B sisteme en die keuse van ‘n doeltreffende lae koste turbine is noodsaaklik in die suksesvolle implementering van dié sisteme. Die doelwit van hierdie tesisprojek is dus om die toepassing van ‘n turbine in ‘n lae graad energie AEH&B sisteem op die proef te stel. ‘n Eksperimentele turbine stel (“Infinity Turbine ITmini”) is aangeskaf, aanmekaargesit en getoets op ‘n pasgemaakte lugtoetsbank. Die toetsdata is gebruik om die turbine te karakteriseer by lae temperatuur (minder as 120 Celsius) en druk (minder as 10 bar) kondisies. ‘n Radiaalinvloeiturbinerotor is ook ontwerp, vervaardig en getoets op die lugtoetsbank om die rotor se karakteristieke te bepaal. In vergelyking met die ITmini-rotor het die radiaalinvloeiturbinerotor effens beter werkverrigting gelewer by diselfde toetsdruk verhoudings. Die werksverrigtingkarakteristieke met lug as vloeimedium van die radiaalinvloeiturbinerotor is gebruik om die rotor te skaleer vir ‘n R123 verkoelmiddel toepassing. Toekomstige werk sluit in om die turbine met ‘n AEH&B sisteem te integreer en die sisteem se werksverrigtingkarakteristieke te bepaal.

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11

Ding, Bowen. "Aerodynamics of low pressure steam turbine exhaust systems." Thesis, University of Cambridge, 2019. https://www.repository.cam.ac.uk/handle/1810/290137.

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The low pressure (LP) exhaust system presents a promising avenue for improving the performance of large steam turbines. For this reason, LP exhaust systems have attracted the attention of the research community for decades. Nevertheless, we still lack understanding of the flow physics and loss mechanisms in the exhaust system, especially at part-load conditions. It is also unclear how the exhaust system should be designed when its required operating range widens. This thesis provides solutions to these aerodynamic issues through experimental and numerical investigations, and provides tools that could contribute to better designs of LP exhaust systems. Firstly, the Computational Fluid Dynamics (CFD) solver ANSYS CFX was validated against experiments performed on a scaled test rig under representative part-load flow conditions. This validation exposed the weakness of Reynolds-averaged Navier-Stokes (RANS) CFD when there is a highly swirling flow and large separation regions in the exhaust diffuser. To facilitate the numerical studies, a series of tools were also developed. A design suite, ExhaustGen, was used to automate the pre- and post-processing of CFD calculations. The exhaust diffuser was parametrised using "Minimum Energy Curves", which reduce the dimension of parameter space. Further, a suitable stage-hood interface treatment (Multiple Mixing Planes) was chosen to predict the circumferentially non-uniform flow in the exhaust hood at low computational cost. Numerical investigation of the baseline geometry provided insights into the key flow features and loss mechanisms in the exhaust system, over a wide range of operating conditions. In particular, the bearing cone separation was identified as a key source of loss at part-load conditions. The effect of stage-hood interaction on the performance and design of the exhaust system was studied by varying the rotor blade design, which can positively influence system performance. Finally, a global sensitivity study was performed to identify the most influential design parameters of the exhaust hood. These findings allow, for the first time, LP exhaust hood performance maps to be constructed, so that the benefits of choosing a suitable hood geometry and blade design can be revealed. The thesis also offers contribution towards formulating LP exhaust system design guidance for a wide operating range.

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Sharpe, Jacob Andrew. "3D CFD Investigation of Low Pressure Turbine Aerodynamics." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1495872867696744.

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13

Otieno-Alego, Vincent. "Pitting corrosion of low alloy steels in simulated low pressure steam turbine environments." Thesis, Queensland University of Technology, 1993. https://eprints.qut.edu.au/107093/1/T%28S%29%2014%20Pitting%20corrosion%20of%20low%20alloy%20steels%20in%20simulated%20low%20presuure%20steam%20turbine%20environments.pdf.

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This study has examined the pitting tendency of A-470, GFA and S231 turbine rotor disc low alloy steels (LAS) under conditions representative of a contaminated turbine environment. Corrosion potential-time curves and potentiodynamic polarization methods have been used to determine pitting characteristics whilst surface analysis techniques were used to characterize the nature of the passive films formed and the corrosion products in the pits and the surrounding areas. The study demonstrated the suitability of a computerized curve matching routine (SYMADEC) for SYnthesizing, MAtching and DEConvolution of polarization curves typical of those observed for metals exhibiting active-passive behaviour and subsequent film breakdown. Pure iron in nitrogen purged 0.1 M sodium benzoate was chosen as a model system. Potentiodynamic scan rate affects the shape of anodic curves and the influence of this variable on the input parameters required to synthesize an anodic polarization curve was established. Empirical linear relationships were derived over the scan rate selected and this lead to the prediction of curves at other scan rates which were good matches with the experimental curves provided the scan rate was not too far outside the original range chosen. SYMADEC was used to analyze the experimental polarization curves for A-470 steel in a simulated turbine environment. A solution containing 2 ppm NaCl, 2 ppm Na2S04 , 2 ppm NaOH and 5 ppm Si02 was employed as a background electrolyte. The effect of the dissolved oxygen (D02) level on the input parameters used to synthesize curves to match experimental ones obtained in different D02 media was established. Comparison with the same input parameters required to match curves obtained at different potential scan rates showed a similar trend indicating that a comparable polarizing effect can be achieved by increasing the D02 level of the electrolyte.

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14

Reichstein, Georg A. [Verfasser]. "Secondary Circulation in a Low-Pressure Turbine / Georg A. Reichstein." München : Verlag Dr. Hut, 2014. http://d-nb.info/1064559948/34.

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15

Marx, Martin [Verfasser]. "Unsteady Work Processes in a Low Pressure Turbine / Martin Marx." München : Verlag Dr. Hut, 2016. http://d-nb.info/109781775X/34.

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16

Vogt, Damian. "Experimental Investigation of Three-Dimensional Mechanisms in Low-Pressure Turbine Flutter." Doctoral thesis, KTH, Energy Technology, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205.

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The continuous trend in gas turbine design towards lighter, more powerful and more reliable engines on one side and use of alternative fuels on the other side renders flutter problems as one of the paramount challenges in engine design. Flutter denotes a self-excited and self-sustained aeroelastic instability phenomenon that can lead to material fatigue and eventually damage of structure in a short period of time unless properly damped. The design for flutter safety involves the prediction of unsteady aerodynamics as well as structural dynamics that is mostly based on in-house developed numerical tools. While high confidence has been gained on the structural side unanticipated flutter occurrences during engine design, testing and operation evidence a need for enhanced validation of aerodynamic models despite the degree of sophistication attained. The continuous development of these models can only be based on the deepened understanding of underlying physical mechanisms from test data.

As a matter of fact most flutter test cases treat the turbomachine flow in two-dimensional manner indicating that the problem is solved as plane representation at a certain radius rather than representing the complex annular geometry of a real engine. Such considerations do consequently not capture effects that are due to variations in the third dimension, i.e. in radial direction. In this light the present thesis has been formulated to study three-dimensional effects during flutter in the annular environment of a low-pressure turbine blade row and to describe the importance on prediction of flutter stability. The work has been conceived as compound experimental and computational work employing a new annular sector cascade test facility. The aeroelastic response phenomenon is studied in the influence coefficient domain having one blade oscillating in various three-dimensional rigid-body modes and measuring the unsteady response on several blades and at various radial positions. On the computational side a state-of-the-art industrial numerical prediction tool has been used that allowed for two-dimensional and three-dimensional linearized unsteady Euler analyses.

The results suggest that considerable three-dimensional effects are present, which are harming prediction accuracy for flutter stability when employing a two-dimensional plane model. These effects are mainly apparent as radial gradient in unsteady response magnitude from tip to hub indicating that the sections closer to the hub experience higher aeroelastic response than their equivalent plane representatives. Other effects are due to turbomachinery-typical three-dimensional flow features such as hub endwall and tip leakage vortices, which considerably affect aeroelastic prediction accuracy. Both effects are of the same order of magnitude as effects of design parameters such as reduced frequency, flow velocity level and incidence. Although the overall behavior is captured fairly well when using two-dimensional simulations notable improvement has been demonstrated when modeling fully three-dimensional and including tip clearance.

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Burton, Zoe. "Analysis of low pressure steam turbine diffuser and exhaust hood systems." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10531/.

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This thesis concerns the computational modelling of low pressure (LP) steam turbine exhaust hood flows. A test case for LP last stage blades (LSBs) with a full aerodynamic definition and an accompanying exhaust hood was developed which is representative of current industrial practice. The test case geometry is freely available allowing other researchers to build on this work and is the first of its kind. Studies on this Durham Stage and Exhaust Hood Test Case showed the geometry produces a representative flow pattern and performance metrics comparable to other published research. Using the test case, the effect of condenser cooling water pressure gradient on the hood flow was computed for the first time. A generic boundary condition was developed to represent the transverse condenser cooling water flow and, when applied to the test case, was shown to have a larger influence on the flow asymmetry within the hood than the tip leakage jet. This thesis describes the first application of the non-linear harmonic (NLH) method to couple the LSBs to the exhaust hood. This method enabled the circumferential non-uniformity which develops in the exhaust hood to be transferred across the interface to the stage, in half the computational demand of the full annulus frozen rotor approach. The first review of the influence of inlet circumferential asymmetry on the hood flow field highlighted that modelling its effect is not as crucial as indicated in the literature, unless the diffuser axial length is very compact or if off-design flows are to be studied. A series of recommendations and guidelines for the CFD modelling of steam turbine exhaust hood flows based on this work are supplied. Experimental validation of the Durham Stage and Exhaust Hood Test Case and a comparison of full unsteady studies with the NLH method should be the next steps in this research.

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SINGH, NAVTEJ. "A STUDY OF SEPARATED FLOW THROUGH A LOW-PRESSURE TURBINE CASCADE." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1109095348.

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McQuilling, Mark W. "DESIGN AND VALIDATION OF A HIGH-LIFT LOW-PRESSURE TURBINE BLADE." Wright State University / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=wright1189792837.

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20

Antinori, Giulia [Verfasser]. "Uncertainty analysis and robust optimization for low pressure turbine rotors / Giulia Antinori." Aachen : Shaker, 2017. http://d-nb.info/1138179019/34.

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Habermann, Jan [Verfasser]. "Reynolds Stress Anisotropy in a Two-Stage Low-Pressure Turbine / Jan Habermann." München : Verlag Dr. Hut, 2018. http://d-nb.info/1172581606/34.

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Hollon, Brian. "EXPERIMENTAL INVESTIGATION OF SEPARATION IN A LOW PRESSURE TURBINE BLADE CASCADE MODEL." UKnowledge, 2003. http://uknowledge.uky.edu/gradschool_theses/304.

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The flow field around a low pressure turbine blade is examined using smoke-wire flow visualization, static surface pressure measurements, and particle image velocimetry (PIV). The purpose of the experimental study is to investigate the transition and separation characteristics on low pressure turbine blades under low Reynolds number (Re) and varying freestream turbulence intensity (FSTI). A cascade model consisting of 6 Pratt andamp; Whitney PAK-B low pressure turbine blades was examined in a wind tunnel using PIV and flow visualization. Smoke-wire visualization was performed for test section exit angles of 93°, 95°, and 97°, in the range Re = 3 · 104 to 9 · 104 and three levels of FSTI varied with a passive grid. The locations of separation and transition were determined to be approximately 45% and 77% of the suction surface length, respectively, based upon the smoke stream lines observed in the images, and appear to be independent of Re, turning angle, and FSTI. The maximum size of the separation bubble was found to decrease with increasing Re, turning angle, and FSTI. PIV images from three camera views were processed for an exit angle of 95° and a Re range of 3:0 · 104 to 30:0 · 104 and three levels of FSTI. Velocity, vorticity, and reversed flow probability field plots were generated along with velocity, vorticity, and RMS velocity profiles. The point of separation point was determined to be from 63% SSL to 67% SSL. The area of reversed flow was computed for each image pair from camera views 1 and 3, as an approxiamtion of the relative size of the separation region. For low Re and FSTI cases the area was much larger than for higher FSTI cases at any Re. The raw PIV images include some of the rst clear pictures of the turbulent flow structures forming in the unsteady shear layer over the suction surface of low pressure turbine blades. Several movies are compiled that show how the geometry and location of the shear layer evolve in time for a given set of flow conditions.

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Ramakumar, Karthik. "ACTIVE FLOW CONTROL OF LOW PRESSURE TURBINE BLADE SEPARATION USING PLASMA ACTUATORS." UKnowledge, 2006. http://uknowledge.uky.edu/gradschool_theses/359.

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The current study examines plasma actuators as flow control devices. The actuators are placed on a turbine blade profile in a 2D turbine cascade for separation flow control. The configuration involves copper strips separated by a layer of dielectric material, across which an AC electric potential in the range of 5 kHz and 5 kV is applied. The efficiency of the actuator is monitored by measuring power input and flow control effectiveness. Preliminary observations are performed for a quiescent case on a flat plate profile to analyze the average and instantaneous velocities generated by the actuator for varied input parameters, such as waveform shape and frequency. Observations include the generation of starting and standing vortices that may be leveraged for unsteady flow control applications. In the case of turbine flow control, the Pratt andamp; Whitney Pak-B blade profile is used to determine the actuator performance for separation reduction at Reynolds number O(104). The results are compared with flow control on and off states for varied actuator input frequency, power, duty cycle and freestream velocity. Pressure measurements are conducted for the actuated case that show reduced separation and increased main flow velocity. Experimental diagnostics include PIV, 7-hole probe, and smoke-wire flow visualization techniques. Phase locked PIV performed at different forcing frequencies reveals the generation of cross-stream vortices providing re-attachment of the separated flow. During the off periods of the cycle the region of separation is observed to creep back to its original separation point. Various fields-of-view show the structure of these cross-stream vortices at different phases. While the actuator is seen to accelerate the flow in the immediate region of the plasma, the generation of starting vortices demonstrates that unsteady actuation is a more effective form of flow control.

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24

Bury, Mark Eric. "Influence of Reynolds number and blade geometry on low pressure turbine performance." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/50310.

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Cranstone, Alexander William. "Low pressure turbine design for a future high bypass ratio aero-engine." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610530.

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Андріїшин, Mихайло Петрович, Костянтин Іванович Капітанчук, Назар Михайлович Андріїшин, Kostiantyn Kapitanchuk, and Константин Иванович Капитанчук. "Natural gas turbine flow meters calibrations in low gas flow pressure situations." Thesis, Національний авіаційний університет, 2018. http://er.nau.edu.ua/handle/NAU/39801.

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In the article criteria of possible turbine flow meters calibrations with natural gas, parameters fluctuations are determined Article presents experimentation results of natural gas parameters influence on processes that occur in turbine flow meters. In the article criteria of possible turbine flow meters calibrations with natural gas, parameters fluctuations are determined. It is known that metrological parameters of the turbine flow meter in operating systems will deter from certificated values. With pressure, temperature or other fluctuations of a flow physical parameters the flow meter's results will occur within of an error space determined by Reynolds number equation for current flow passing through turbine grille. With Reynolds numbers constant aspect ratio the relative error of a flow meter will stay irrelevant of type of the environment. It is suggested to use this value as a criterion that is not affected by thermodynamic parameters and physical characteristics of an environment but of turbine grille model and mechanical state of a flow meter. Turbine flow meter SM-RI-X-KG1000, DN200 was used for experiment with flow volume varies of 80 m3/h to 1600 m3/h and pressure varies of 100 kPa to 700. Results of theoretical calculations and experimental research data for Reynolds number ratio is shown on a graph of a turbine flow meter speed on pressure dependency. It is determined that the flow meter designed for the low-pressure environment should be calibrated for actual range of operating environment pressure and temperature values
У статті визначено критерії калібрувань турбінних витратомірів природного газу. Запропоновано використовувати значення числа Рейнольдса як критерій, на який не впливає термодинамічні параметри та фізичні характеристики середовища, параметри турбінної решітки. модель і механічний стан витратоміра. Для експерименту використовували турбінний витратомір SM-RI-X-KG1000, DN200 з об'ємом потоку від 80 м3 / год до 1600 м3 / год, а тиск змінювався від 100 кПа до 700. Результати теоретичних розрахунків та даних експериментальних досліджень для числа Рейнольдса показано на графіку швидкості турбінного витратоміра на залежність від тиску. Встановлено, що витратомір, призначений для середовища низького тиску, повинен бути відкалібрований для фактичного діапазону тисків робочого середовища та значень температури
В статье определены критерии калибровок турбинных расходомеров природного газа. Предложено использовать значение числа Рейнольдса как критерий, на который не влияет термодинамические параметры и физические характеристики среды, параметры турбинной решетки. модель и механическое состояние расходомера. Для эксперимента использовали турбинный расходомер SM-RI-X-KG1000, DN200 с объемом потока от 80 м3 / ч до 1600 м3 / ч, а давление изменялось от 100 кПа до 700 Результаты теоретических расчетов и данных экспериментальных исследований для числа Рейнольдса показано на графике скорости турбинного расходомера в зависимости от давления. Установлено, что расходомер, предназначенный для среды низкого давления, должен быть откалиброван для фактического диапазона давлений рабочей среды и значений температуры

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27

Ahmad, Mansoor. "Experimental assessment of droplet impact erosion of low pressure steam turbine blades." Aachen Shaker, 2009. http://d-nb.info/998626953/04.

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28

Schulze, Christian [Verfasser]. "Influence of Combined Inflow Distortions on a Low Pressure Turbine at Low Reynolds Numbers / Christian Schulze." München : Verlag Dr. Hut, 2018. http://d-nb.info/1166482634/34.

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29

Sanders, Darius Demetri. "CFD Modeling of Separation and Transitional Flow in Low Pressure Turbine Blades at Low Reynolds Numbers." Diss., Virginia Tech, 2009. http://hdl.handle.net/10919/29303.

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There is increasing interest in design methods and performance prediction for turbine engines operating at low Reynolds numbers. In this regime, boundary layer separation may be more likely to occur in the turbine flow passages. For accurate CFD predictions of the flow, correct modeling of laminar-turbulent boundary layer transition is essential to capture the details of the flow. To investigate possible improvements in model fidelity, both two-dimensional and three-dimensional CFD models were created for the flow over several low pressure turbine blade designs. A new three-equation eddy-viscosity type turbulent transitional flow model originally developed by Walters and Leylek was employed for the current RANS CFD calculations. Flows over three low pressure turbine blade airfoils with different aerodynamic characteristics were simulated over a Reynolds number range of 15,000-100,000, and predictions were compared to experiments. The turbulent transitional flow model sensitivity to inlet turbulent flow parameters showed a dependence on free-stream turbulence intensity and turbulent length scale. Using the total pressure loss coefficient as a measurement of aerodynamic performance, the Walters and Leylek transitional flow model produced adequate prediction of the Reynolds number performance in the Lightly Loaded blade. Furthermore, the correct qualitative flow response to separated shear layers was observed for the Highly Loaded blade. The vortex shedding produced by the separated flow was largely two-dimensional with small spanwise variations in the separation region. The blade loading and separation location was sufficiently predicted for the Aft-Loaded L1A blade flowfield. Investigations of the unsteady flowfield of the Aft-Loaded L1A blade showed the shear layer produced a large separation region on the suction surface. This separation region was located more downstream and significantly reduced in size when impinged upon by the upstream wakes, thus improving the aerodynamic performance consistent with experiments. For all cases investigated, the Walters and Leylek transitional flow model was judged to be sufficient for understanding the separation and transition characteristics, and superior to other widely-used turbulence models in accuracy of describing the details of the transitional and separated flow. This research characterized and assessed a new model for low Reynolds number turbine aerodynamic flow prediction and design improvement.
Ph. D.

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30

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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31

Schneider, Carsten [Verfasser]. "On the Unsteady Secondary Flow Inside a Low Pressure Turbine Stage / Carsten Schneider." Aachen : Shaker, 2015. http://d-nb.info/1071527738/34.

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32

Kessar, Alexandros. "L2F measurements for low engine order excitations in a high pressure turbine stage /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-376.

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33

Lipfert, Martin [Verfasser]. "Unsteady Aerodynamics of a Low Pressure Turbine at Off-Design Operation / Martin Lipfert." München : Verlag Dr. Hut, 2015. http://d-nb.info/1079768971/34.

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34

Murawski, Christopher G. "Unsteady flows in a two-dimensional linear cascade with low-pressure turbine blades /." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1488192960170437.

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35

Fuhrer, Christopher [Verfasser]. "Numerical Investigation on Spontaneous Condensation in Low-Pressure Steam Turbine Aeroelasticity / Christopher Fuhrer." Düren : Shaker, 2021. http://d-nb.info/1238497632/34.

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36

Jayasuriya, Jeevan. "Experimental Investigations of High Pressure Catalytic Combustion for Gas Turbine Applications." Doctoral thesis, KTH, Kraft- och värmeteknologi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-134445.

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This work is devoted to generate knowledge and high quality experimental data of catalytic combustion at operational gas turbine conditions. The initial task of the thesis work was to design and construct a high pressure combustion test facility, where the catalytic combustion experiments can be performed at real gas turbine conditions. With this in mind, a highly advanced combustion test facility has been designed, constructed and tested. This test facility is capable of simulating combustion conditions relevant to a wide range of operating gas turbine conditions and different kinds of fuel gases. The shape of the combustor (test section) is similar to a “can” type gas turbine combustor, but with significant differences in its type of operation. The test combustor is expected to operate at near adiabatic combustion conditions and there will be no additions of cooling, dilution or secondary supply of air into the combustion process. The geometry of the combustor consists of three main zones such as air/fuel mixing zone, catalytic reaction zone and downstream gas phase reaction zone with no difference of the mass flow at inlet and exit. The maximum capacity of the test facility is 100 kW (fuel power) and the maximum air flow rate is 100g/s. The significant features of the test facility are counted as its operational pressure range (1 – 35 atm), air inlet temperatures (100 – 650 °C), fuel flexibility (LHV 4 - 40 MJ/m3) and air humidity (0 – 30% kg/kg of air). Given these features, combustion could be performed at any desired pressure up to 35 bars while controlling other parameters independently. Fuel flexibility of the applications was also taken into consideration in the design phase and proper measures have been taken in order to utilize two types of targeted fuels, methane and gasified biomass. Experimental results presented in this thesis are the operational performances of highly active precious metal catalysts (also called as ignition catalysts) and combinations of precious metal, perovskites and hexaaluminate catalysts (also called as fully catalytic configuration). Experiments were performed on different catalytic combustor configurations of various types of catalysts with methane and simulated gasified biomass over the full range of pressure. The types of catalysts considered on the combustor configurations are palladium on alumina (Pd/AL2O3), palladium lanthanum hexaaluminate (PdLaAl11O19), platinum on alumina (Pt/AL2O3),and palladium:platinum bi-metal on alumina (Pd:Pt/AL2O3). The influence of pressure, inlet temperature, flow velocity and air fuel ratio on the ignition, combustion stability and emission generation on the catalytic system were investigated and presented. Combustion catalysts were developed and provided mainly by the project partner, the Division of Chemical Technology, KTH. Division of Chemical Reaction Technology, KTH and Istituto di Ricerche sulla Combustione (CNR) Italy were also collaborated with some of the experimental investigations by providing specific types of catalysts developed by them for the specific conditions of gas turbine requirements.

QC 20131125

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37

Ahmad, Mansoor [Verfasser]. "Experimental assessment of droplet impact erosion of low-pressure steam turbine blades / Mansoor Ahmad." Aachen : Shaker, 2009. http://d-nb.info/1161302182/34.

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38

MUTNURI, PAVAN KUMAR. "SIMULATION OF FLOW THROUGH LOW-PRESSURE LINEAR TURBINE CASCADE, USING MULTI-BLOCK STRUCTURED GRID." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1070493086.

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39

Kürner, Matthias [Verfasser]. "The Effect of low Reynolds Number on Transition and Unsteadiness in a Low Pressure Turbine Rig / Matthias Kürner." München : Verlag Dr. Hut, 2014. http://d-nb.info/1052375707/34.

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40

POONDRU, SHIRDISH. "Large-Eddy Simulation and Active Flow Control of Low-Reynolds Number Flow through a Low-Pressure Turbine Cascade." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1204873699.

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41

Nessler, Chase A. "Characterization of Internal Wake Generator at Low Reynolds Number with a Linear Cascade of Low Pressure Turbine Blades." Wright State University / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=wright1270749309.

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42

Cuthbertson, Grant. "An experimental investigation of dropwise and filmwise condensation of low pressure steam in tube banks." Thesis, Heriot-Watt University, 1999. http://hdl.handle.net/10399/1246.

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Research to date has highlighted a number of conditions where dropwise condensation may offer heat transfer enhancements over filmwise condensation. Previous studies have shown at pressures above or around atmospheric, dropwise condensation offers significant benefit over filmwise. However, some of this research suggests that as the system pressure is reduced below atmospheric, the benefits of dropwise condensation diminish rapidly, to the extent that, at pressures around 50mbar the benefits of dropwise over filmwise are minimal. This thesis details a series of experiments which were conducted to investigate the heat transfer and pressure drop distributions in tube bundles during both dropwise and filmwise condensation of steam. The primary objective of the work was to determine the design implications associated with switching the mode of condensation of a electricity generating steam turbine condenser from the current filmwise mode, to dropwise. Experimental data were obtained from a new purpose build apparatus containing seventy-five, 150mm long titanium tubes, arranged in an in line configuration of five columns and fifteen rows. Dropwise and filmwise data were recorded from each row at test cell inlet pressures down to 50mbar using both pure steam and steam air mixtures. Filmwise heat transfer data indicated that, under most conditions, heat transfer coefficients were generally in agreement with those obtained by previous workers. Heat transfer data obtained during dropwise condensation suggested that the benefits of dropwise condensation are not significantly diminished at low pressure, and that, unlike filmwise condensation, inundation has little or no effect in a fifteen row bundle. The data also indicated that the pressure drop characteristics and effects of air are, within experimental error, identical during both modes of condensation and in line with models and theories proposed by previous workers.

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43

McQuilling, Mark. "EXPERIMENTAL STUDY OF ACTIVE SEPARATION FLOW CONTROL IN A LOW PRESSURE TURBINE BLADE CASCADE MODEL." UKnowledge, 2004. http://uknowledge.uky.edu/gradschool_theses/320.

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The flow field around a low pressure turbine (LPT) blade cascade model with and without flow control is examined using ejector nozzle (EN) and vortex generator jet (VGJ) geometries for separation control. The cascade model consists of 6 Pak-B Pratt andamp; Whitney low pressure turbine blades with Re = 30,000-50,000 at a free-stream turbulence intensity of 0.6%. The EN geometry consists of combined suction and blowing slots near the point of separation. The VGJs consist of a row of holes placed at an angle to the free-stream, and are tested at two locations of 69% and 10.5% of the suction surface length (SSL). Results are compared between flow control on and flow control off states, as well as between the EN, VGJs, and a baseline cascade with no flow control geometry for steady and pulsatile blowing. The EN geometry is shown to control separation with both steady and pulsatile blowing. The VGJs at 69% SSL are shown to be much more aggressive than the EN geometry, achieving the same level of separation control with lower energy input. Pulsed VGJs (PVGJ) have been shown to be just as effective as steady VGJs, and results show that a 10% duty cycle is almost as effective as a 50% duty cycle. The VGJs at 10.5% SSL are shown to be inefficient at controlling separation. No combination of duty cycle and pulsing frequency tested can eliminate the separation region, with only higher steady blowing rates achieving separation control. Thus, the VGJs at 69% SSL are shown to be the most effective in controlling separation.

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44

Singh, Gursharanjit. "The study of the interactions between a low pressure steam turbine and axial-radial diffuser." Thesis, Queen Mary, University of London, 2015. http://qmro.qmul.ac.uk/xmlui/handle/123456789/15029.

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Specific power output from a Low Pressure (LP) steam turbine can be enhanced by increasing the stage efficiency or raising its pressure ratio; both methods are interlinked and must be dealt with together. The latter is achieved by connecting to the exhaust diffuser; space and cost constraints often insist the use of an axial-radial diffuser with high levels of diffusion. The present study aims to investigate the interaction between the last-stage blade and the axial-radial diffuser, which can influence the diffuser performance and thus the total work output from the stage. This work is carried out using CFD simulations of a generic last stage low pressure (LP) turbine and axial-radial exhaust diffuser attached to it. In order to determine the validity of the computational method, the CFD predictions are first compared with data obtained from an experimental test facility. A computational study is then performed for different design configurations of the diffuser and rotor casing shapes. The study focuses on typical flow features such as effects of rotor tip leakage flows and subsequent changes in the rotor-diffuser interactions. The results suggest that the rotor casing shape and diffuser configurations influences the rotor work extraction capability and yields significant improvements in the static pressure recovery.

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45

Zhang, Xue Feng. "Separation and transition control on ultra-high-lift low pressure turbine blades in unsteady flow." Thesis, University of Cambridge, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.613985.

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46

Memory, Curtis L. "Turbulent Transition Behavior in a Low Pressure Turbine Subjected to Separated and Attached-Flow Conditions." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1290996104.

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47

Reimann, Daniel D. "Effects of Spanwise and Discrete Disturbances on Separating Boundary Layers on Low Pressure Turbine Blades." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1761.pdf.

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48

Babajee, Jayson. "Detailed numerical characterization of the separation-induced transition, including bursting, in a low-pressure turbine environment." Phd thesis, Ecole Centrale de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00984351.

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La turbine basse-pression est un composant essentiel d'un turboréacteur car elle entraine la soufflante qui génère la plus grande partie de la poussée dans la configuration actuelle des turboréacteurs à double flux. Dans la perspective d'accroître son rendement en termes de consommation de carburant, il y a une recherche permanente dans la réduction du nombre d'aubage (c'est-à-dire la réduction de la masse) qui implique un chargement plus élevé par aube de rotor. Cet environnement est caractérisé par un écoulement dont le nombre de Reynolds est faible ainsi qu'une large diffusion le long de la partie aval de l'extrados. Par conséquent, l'écoulement le long de cette surface est potentiellement sujet à une séparation laminaire qui, suivant le statut de la bulle de recirculation, pourrait causer une diminution de la performance aérodynamique (sillages plus larges et plus profonds). La présente thèse de doctorat se concentre sur l'investigation du phénomène de la transition induite par séparation dans les écoulements de turbines basse-pression. L'accent est mis sur les prédictions numériques basées sur une approche CFD RANS utilisant le modèle innovant de transition γ-Reθt à deux équations de transport (la première équation pour l'intermittence numérique et la seconde équation pour le nombre de Reynolds dont la longueur caractéristique est l'épaisseur de quantité de mouvement au début de transition γ-Reθt). Neuf aubes différentes de rotor de turbine basse-pression constituent une base de données de référence et couvrent les plages de fonctionnement de différents nombres de Reynolds de sortie isentropique, de nombres de Mach de sortie isentropique, d'intensités de turbulence d'entrée, avec ou sans sillage provenant d'une rangée d'aubes amont et avec deux configurations de rugosité locale. Une première analyse de cette base de données met en évidence l'effet de la séparation sur le début de la transition et sur les performances. La définition d'une corrélation a été tentée et permet de lier le taux de diffusion d'un aubage au nombre de Reynolds de sortie isentropique fia la condition de " Bursting ". Une méthodologie numérique fiable et robuste a été établie afin de prédire la transition dans le cas d'un écoulement amont uniforme. Les résultats sont en bon accord avec les mesures expérimentales même si il a été nécessaire d'adapter les conditions limites dans le but de prédire une séparation laminaire numériquement pour des aubages fortement chargés et fia fort taux de diffusion uniquement. La résolution des profils de vitesse de la couche limite permet d'obtenir une évaluation détaillée des paramètres de la topologie de l'écoulement. Cela fournit une information sur l'épaisseur de quantité de mouvement qui est le paramètre principal définissant les corrélations de transition. La technique " Chimère " des maillages recouvrants est utilisée pour faciliter la modélisation des moyens de contrôle passif pour déclencher la transition. C'est une technique appropriée pour l'implémentation de géométries simples ou plus élaborées.

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49

Dickel, Jacob Allen. "Design Optimization of a Non-Axisymmetric Endwall Contour for a High-Lift Low Pressure Turbine Blade." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1534980581177159.

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50

Pluim, Jonathon Douglas. "DESIGN OF A HIGH FIDELITY WAKE SIMULATOR FOR RESEARCH USING LINEAR CASCADES." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1244039010.

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Dissertations / Theses on the topic 'Low pressure turbine material'

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