Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines最新文献

{"title":"Towards a Better Understanding of Crack Growth in Nickel-Cast Alloys Under Creep-Fatigue and Thermo-Mechanical Fatigue Conditions","authors":"K. M. Kraemer, Falk Mueller, C. Kontermann, M. Oechsner","doi":"10.1115/gt2019-92028","DOIUrl":"https://doi.org/10.1115/gt2019-92028","url":null,"abstract":"\u0000 To ensure the feasibility of gas turbines, despite rising commodity prices and emission restrictions, an enhancement of both their efficiency and flexibility is necessary. The consequential higher loading of components at high temperature conditions calls for an increased use of damage tolerant design approaches. To still guarantee a safe operation, a sound understanding and reliable estimations for crack growth under service conditions is indispensable. In this paper, the results from several projects in this field conducted at the TU Darmstadt and involved partners are summarized to identify and describe the various influences on crack growth under creep-fatigue and thermo-mechanical fatigue (TMF) loading. The activation of damage mechanisms under TMF loading and interactions between them are dependent of the temperature cycle and the respective load phasing. Depending on the type of loading (force- vs. strain-control), contrary influences of the phase shift on the TMF crack growth rates are found. This can partially be attributed to the differences in mean stress evolution. Crack initiation and propagation under creep-fatigue and TMF conditions are also often connected with significant scattering of initiation sites and crack growth rates. One reason for this non-uniform behaviour is the interaction of geometric discontinuities with the microstructure. To investigate the role of the local grain structure for crack initiation and propagation, in-situ observation techniques for crack tip movement and local strain fields were applied. Harsh gradients in the local deformation behaviour were identified as origins of secondary crack initiation. To describe crack growth under creep-fatigue and TMF conditions, the linear accumulation model “O.C.F.” was developed. It is based on the contributions of fatigue, creep and oxidation to crack growth per load cycle. This model is capable to reproduce the effects of time-dependent damage, different load ratios and TMF phase shifts, as well as component geometry. Substantial advantages of this method are its independence from empiric correction factors to assess changing load cycle forms and the possibility to give analytic estimations without the need of extensive data processing. The model is currently validated for three nickel cast alloys, also including single crystalline (SX) and directionally solidified (DS) cast variants, different creep-fatigue and TMF loading scenarios and crack geometries. The model’s linear formulation allows assessing the dominant driver of crack growth at each stage of an experiment. These predictions are compared with fractographic investigations and in-situ observations of crack paths to identify the mechanisms of crack growth under different TMF load cycle forms.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129849981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of Highly Efficient and Robust Ultra-Long Last Stage Blade for High Backpressure","authors":"O. Novak, M. Bobčík, Václav Sláma, Bartoloměj Rudas, J. Kellner, Petr Měšťánek, J. Hlous, Z. Simka, M. Luxa, D. Šimurda, A. Z̆ivný, A. Macálka, J. Ira","doi":"10.1115/gt2019-90350","DOIUrl":"https://doi.org/10.1115/gt2019-90350","url":null,"abstract":"\u0000 For modern steam turbines with large operating range and enhanced efficiency an ultra-long last stage rotor blade in a low pressure turbine part for high backpressure and 50 Hz fixed speed operation have been developed. An advanced design approach was used to create the blade shape with a high thermodynamic efficiency, high natural frequencies and a very high safety factor of average radial static stress in the blade span. Furthermore, the tip section of the bucket was improved to decrease a static tension and the hub section was refined to simplify the assembly. Tip and hub airfoils were experimentally validated in a supersonic wind tunnel. An advanced in-house procedure using numerical analysis to predict a potential danger of unstalled flutter was carried out for wide range of operating conditions.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128487468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Dynamics and Aeroelasticity of Airborne Diesel Engine Turbochargers","authors":"R. Mcgowan, M. Murugan, Michael T. Szedlmayer, Kenneth S. Kim, Kurt M. Kruger, David J. Gondol, Chol-Bum M. Kweon, Peter Clerkin, R. Meininger, Joseph A. Gibson, C. Lindsey, Bernard N. Acker, Marshall R. Musser","doi":"10.1115/gt2019-91843","DOIUrl":"https://doi.org/10.1115/gt2019-91843","url":null,"abstract":"\u0000 Compared to turbodiesel technology for ground vehicles, the increasing application of turbochargers in aircraft diesel engines presents a unique set of structural dynamics and aeroelasticity considerations due to their more extreme operating conditions. In particular, blade vibration and flutter are two related but distinct phenomena that impact the design of these turbochargers and reliable operation over their lifetime. Deformation or fatigue due to blade excitation can reduce efficiency or cause components to fail prematurely. The existing literature on turbomachinery covers many research efforts to analyze these phenomena by investigating the physical mechanisms responsible as well as the relationships between the fluid and solid dynamics. This review paper emphasizes those efforts most relevant to airborne diesel turbochargers, including research focusing on altitude effects on centrifugal compressors. Early work in which the dominant parameters for modeling turbocharger behavior were identified is highlighted as are current efforts to develop higher-fidelity models. An overview of existing and proposed techniques for measuring and controlling blade resonance is also given. Finally, an experimental facility for testing of turbochargers is proposed. The facility will include a nonintrusive stress measurement system and enable measurement of blade deflection/vibration together with blade stress, temperature, pressure, and flow rate across a range of simulated altitudes. The goal will be to characterize the blade bending modes, resonances, and critical speeds for various simulated altitude, pressure, temperature, and flow rate conditions so that designs may be devised that could prevent or avoid the associated failure modes in airborne diesel applications.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"202 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127428057","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Verification of Combined Main Steam Valve Pressure Distribution and Vibration Characteristics With Downscale Model Test on Air Condition","authors":"Fumiyuki Suzuki, S. Nishida, Shinji Fukao, Megumu Tsuruta","doi":"10.1115/gt2019-90406","DOIUrl":"https://doi.org/10.1115/gt2019-90406","url":null,"abstract":"\u0000 In order to enhance the efficiency and reduce the manufacturing cost of steam turbine, combined main steam valve consisting of main stop valve and control valve in the same casing has been developed. Combined main steam valve with improved flow path at internal structure will reduce pressure loss. A downscale model test on air condition was conducted to verify pressure distribution characteristics. Experimental result and numerical result obtained by computational fluid dynamics (CFD) showed reasonable agreement in pressure loss and static pressure at each flow point within the design operation range. Main stop valve (SV) and control valve (CV) vibration characteristics tests were performed simultaneously for the stability verification of governing operation from start up to full load. We confirmed that CV aerodynamic added damping ratio was positive under all measured condition of CV stroke and pressure ratio, and self-excited vibration was not generated. We also confirmed that pressure fluctuation acting on main stop valve body was sufficiently small within the operation range. Meanwhile, in the case where pressure ratio or CV stroke deviated from the operation range, pressure fluctuation around main stop valve increased. Based on CFD result and detailed analysis of experimental result, it was found that steam flow along valve seat separates periodically, which revealed the mechanism of increasing pressure fluctuation around main stop valve. By reflecting on these results, the reliability of new combined main steam valve has substantially been enhanced.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129147026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and Numerical Assessment of the Impact of Part-Span Connectors on Turbine Efficiency and Flow Field","authors":"C. Brüggemann, M. Schatz, D. Vogt, F. Popig","doi":"10.1115/gt2019-91815","DOIUrl":"https://doi.org/10.1115/gt2019-91815","url":null,"abstract":"\u0000 This study presents the results of measurements in an industrial steam turbine test rig operated at the Institute of Thermal Turbomachinery and Machinery Laboratory (ITSM) in Stuttgart, Germany. In order to ensure safe operation over a wide range of operating conditions the last and penultimate rotor blade rows of this turbine feature Part-Span Connectors (PSC). The PSC provide additional coupling and mechanical damping during operation, however, they present a major obstacle to the flow, thus causing additional aerodynamic loss. The focus of the present work is on the aerodynamic impact of the PSC on the flow field of the last stage. To capture this impact, an extensive measurement campaign over a wide range of operating points was performed using two last blade row configurations that are identical with regard to the blade design, except for the fact that one features free-standing blades while the second is equipped with PSC. A performance assessment of these two configurations based on detailed probe measurements and overall turbine efficiency is presented. Additionally, a detailed comparison of 3D CFD-results employing an equilibrium steam (EQS) model and a non-equilibrium steam (NES) model for both configurations is shown with good agreement to the test data. However, comparing the two models reveals major differences whenever there is condensation occurring close to the evaluation plane, thus the advantage of applying the NES model is presented.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"144 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115681959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Labyrinth Fin Wear on Aerodynamic Performance of Turbine Stages: Part II — Mushrooming Damages","authors":"Xinbo Dai, Xin Yan","doi":"10.1115/gt2019-90153","DOIUrl":"https://doi.org/10.1115/gt2019-90153","url":null,"abstract":"The main function of labyrinth seal is to control leakage flow in clearance that involves with rotating and stationary parts. Therefore, the effective of clearance gap in labyrinth seal is critical to sealing, heat transfer and vibration characteristics. However, due to the mechanical expansions, vibrations, thermal stress, misalignment of seal components in transient periods of startup, shutdown and hot restart, the stationary and rotating parts of the labyrinth seal are likely to contact each other, causing wear damages in labyrinth fin. Mushrooming damages are often occurred in the rubbing events when labyrinth fin is made of soft material compared with the opposite component. To investigate how mushrooming damage affects the leakage performance of labyrinth seal, many numerical and experimental studies have been carried out in last decades. However, little attention has been paid on the influence of labyrinth fin mushrooming on aerodynamic performance of turbine stages. In this study, using the RANS equations solution methods, the effect of labyrinth fin mushrooming on isentropic efficiency, leakage rates, outlet flow angles, reaction degrees, profile static pressure distributions and flow fields in turbine stages were investigated at three different mushrooming radii and three effective clearances. It shows the leakage rate is increased with increasing the mushroom radius and effective clearance. At the same effective clearance, as the mushrooming radius increases from 0.2mm to 0.4mm, the leakage rate is increased by about 0.19–0.32%, and the overall isentropic efficiency is decreased by 0.78%. At the same mushrooming radius, as the effective clearance increases from 1mm to 1.4mm, the leakage rate is increased by 0.21–0.31%, and the overall isentropic efficiency is decreased by 0.65%. As mushroom radius and effective clearance increase, the secondary flows near hub and shroud are intensified and developed along axial direction, causing pronounced aerodynamic loss in turbine stages.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"1240 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128233893","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Preliminary CFD Design of a Compressor and Combustor System Towards a 100 kW Hydrogen Fuelled Micro Gas Turbine","authors":"C. Devriese, W. Pennings, H. D. Reuver, R. Bastiaans, W. D. Paepe","doi":"10.1115/gt2019-91342","DOIUrl":"https://doi.org/10.1115/gt2019-91342","url":null,"abstract":"\u0000 Within the context of an ever-increasing share of wind, solar and emerging tidal power, the need to store energy, not only on the short term, but also in the medium to long-term to balance out the power grid will become more important in the near future. One of the most promising routes for this mid- to long term storage, is to produce hydrogen through electrolysis using excess electricity and store it. Instead of using this hydrogen then to generate electricity in a conventional, large, power plant, a more efficient route is to use it in a Decentralised Energy System (DES) using micro Gas Turbines (mGTs). Although the mGT presents itself as a promising option to convert pure hydrogen into electricity in this DES framework, several challenges, linked to the necessary increase of Turbine Inlet Temperature (TIT) for efficiency increase to make the unit compatible and the use of pure hydrogen in the combustor, still need to be overcome. In this paper we present the first steps towards a fully hydrogen fuelled mGT. Firstly, a full thermodynamic cycle analysis was performed to determine the optimal operating parameters, such as compressor pressure ratio and mass flow rate, air-to-fuel ratio and TIT. Secondly, a full CFD design and optimisation of the compressor and the combustion chamber was performed (steady and transient RANS and LES). CFD simulations of the compressor and combustion chamber matched the 1D performance calculations and also reached the desired performance goals. This CFD supported validation of the component performance shows that the design of a pure hydrogen combustion chamber for mGT applications is possible.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"453 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116410535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Application of the Nozzle Analogy to Easily Predict Steam Turbine Performance With Minimal Geometric Input","authors":"W. F. Fuls, J. Clark, A. Marx","doi":"10.1115/gt2019-90891","DOIUrl":"https://doi.org/10.1115/gt2019-90891","url":null,"abstract":"\u0000 A simple method for modelling steam turbines using a nozzle analogy was recently published. The method describes both stator and rotor components of a turbine with an appropriate nozzle definition, and makes use of the traditional velocity triangles to determine work output. What makes the method convenient is that it only requires a reasonable estimate of the effective nozzle throat area per blade row, as well as properly chosen loss coefficients. A complete turbine train with multiple stages can easily be solved using a simple 1-D pressure correction method. The method was demonstrated to match detailed inter-stage turbine data quite accurately.\u0000 This paper elaborates on the application of the method. It presents a more thorough procedure for establishing the nozzle throat areas using a turbine lay-out drawing, as well as consideration of possible reaction ratio variation between successive stages. Furthermore, the loss coefficients are determined using the methods described by Traupel and Zehner. The paper presents these in a compressed and digitized format for easy implementation in a software code.\u0000 A case study is presented to show how the model can quantify improvements to blade profiles. Another case study models a complete boiler feed pump turbine connected to the feedwater pumps and includes the partial arc governing stage and cold re-heat supply. This specific model demonstrated the method’s ability to accurately model a turbine at low load and high back pressure conditions.\u0000 Turbine system modelers can apply the method presented here to their own equipment and obtain trustworthy results without the need for detailed profile geometry or complex CFD analyses. The method is however limited to subsonic flow between blade rows, hence some modern transonic last stage blade designs might not be adequately represented.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122215377","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Advanced Last Stage Blade for Nuclear Power Plant Upgrades","authors":"C. Siewert, James Mccracken, T. Thiemann","doi":"10.1115/gt2019-90860","DOIUrl":"https://doi.org/10.1115/gt2019-90860","url":null,"abstract":"\u0000 Utility steam turbines for electrical power generation are used at many places worldwide with different ambient conditions and different power plant configurations resulting in a variety of environmental and operational conditions. In some environments and operational conditions excitation mechanisms exist which may result in elevated Last Stage Blade vibrations. A particular example occurs in some steam turbine modernization projects, in which modern Last Stage Blade designs are applied in configurations with retained outer casing and diffusor designs from the original turbine design.\u0000 In this paper, operational experience with an advanced Last Stage Blade coupled by damping elements is presented. In addition, the background leading to the development of this Last Stage Blade is outlined in this paper. Vibration measurement data obtained from field measurements in certain modernized units with retained outer casings from original installation is summarized and compared to the corresponding data for a freestanding Last Stage Blade previously used in these units showing the vibrational behavior of the newly developed Last Stage Blade. Results from field inspections are also presented. The data and inspections show the Last Stage Blade with damping elements do not exhibit elevated vibrations previously indicated.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129672516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fretting Induced Fatigue Failure in Steam Turbine Blades","authors":"Vamadevan Gowreesan, Kyrylo Grebinnyk","doi":"10.1115/gt2019-90106","DOIUrl":"https://doi.org/10.1115/gt2019-90106","url":null,"abstract":"\u0000 Fretting occurs when there is cyclic relative motion of extremely small amplitude between two tightly fit mating surfaces. In this process, the tight fitting load may lead to adhesion of mating surface. The subsequent relative movement breaks the adhesion and lead to local grooves and pits. The localized damage in conjunction with the stresses associated with the cyclic relative motion may lead to surface cracking. This crack subsequently may propagate by fatigue provided there is high enough cyclic stress at that location.\u0000 The paper discusses a blade failure induced by such fretting related fatigue. The metallurgical evaluation of the fracture surfaces of the blades showed evidence of classical fatigue failure. However, the crack initiation location did not coincide with high stress location identified by the finite element analysis. This discrepancy along with the evidence of fretting at the crack initiation sites confirms that failures were induced by fretting. Finally, some methods to eliminate or minimize fretting damage are discussed.","PeriodicalId":105494,"journal":{"name":"Volume 8: Microturbines, Turbochargers, and Small Turbomachines; Steam Turbines","volume":"20 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122968182","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}