Articles de revues sur le sujet « Turbine Bypass Valve »
Pour voir les autres types de publications sur ce sujet consultez le lien suivant : Turbine Bypass Valve.
Créez une référence correcte selon les styles APA, MLA, Chicago, Harvard et plusieurs autres
Consultez les 50 meilleurs articles de revues pour votre recherche sur le sujet « Turbine Bypass Valve ».
À côté de chaque source dans la liste de références il y a un bouton « Ajouter à la bibliographie ». Cliquez sur ce bouton, et nous générerons automatiquement la référence bibliographique pour la source choisie selon votre style de citation préféré : APA, MLA, Harvard, Vancouver, Chicago, etc.
Vous pouvez aussi télécharger le texte intégral de la publication scolaire au format pdf et consulter son résumé en ligne lorsque ces informations sont inclues dans les métadonnées.
Parcourez les articles de revues sur diverses disciplines et organisez correctement votre bibliographie.
1
Zou, Z., M. Yang, S. Zhou, Z. Ding, Y. Tian et K. Deng. « Investigation of inter-stage passive flow control for turbine performance improvement on regulated two-stage turbocharger ». Journal of Physics : Conference Series 2217, no 1 (1 avril 2022) : 012078. http://dx.doi.org/10.1088/1742-6596/2217/1/012078.
Texte intégralRésumé :
Abstract The flow field coupling effect between the HPT (high pressure turbine) and LPT (low pressure turbine) introduces a particular flow structure to the two-stage turbocharging system. Compared to the isolated turbines, the performance of these two connected turbines will inevitably be affected by each other. However, in the open state of the bypass valve, the influence of the bypass flow on this flow field coupling effect is still unknown. In this study, the inter-stage performance interaction of regulated two-stage turbocharger was investigated through the three-dimensional numerical method. With the bypass valve open, the influence of different positions of the bypass branch on the inter-stage coupling effects is investigated. The results manifest that the different positions of the bypass branch significantly change the performance of low pressure turbine and the flow interactions within the inter-stage. When the bypass branch is on the right, the LPT efficiency improves by approximately 2.2%. The detailed flow field analysis of the inter-stage pipe, volute and rotor is conducted to reveal the flow mechanism behind the inter-stage interactions. Based on this investigation, a new passive flow control scheme is proposed to ameliorate the swirling flow at the LPT inlet and improve the performance of LPT.
2
Gregory, Brent A., et Oleg Moroz. « Gas Turbine Cooling Flows and Their Influence in Output ». Mechanical Engineering 137, no 03 (1 mars 2015) : 48–54. http://dx.doi.org/10.1115/1.2015-mar-4.
Texte intégralRésumé :
This article presents the importance of understanding cooling flow monitoring especially when applied to land-based gas turbines. Cooling flows are necessary for the engine to function; however, too much cooling has a negative impact on the performance and output. Strategically placed instrumentation in the cooling flow delivery system can monitor the health and hence the output of the gas turbine generator utilized in a simple or combined cycle operation. In order to monitor cooling flows, a good approach is to look at disc cavity temperatures as well as bypass valve positions. It is best to trend both bypass valve position and disc cavity temperatures over a range of temperatures and engine load operation to get a better idea if the orifice plates in the main lines are sized properly. A quick way to determine whether there are cooling issues in an engine or not is to trend disc cavity temperature and bypass valve positions {AQ: Edits have been made in this sentence “A quick…valve positions.” for better readability. Please check and correct if necessary.}
3
Amano, R. S., et G. R. Draxler. « High-Pressure Steam Flow in Turbine Bypass Valve System Part 1 : Valve Flow ». Journal of Propulsion and Power 18, no 3 (mai 2002) : 555–60. http://dx.doi.org/10.2514/2.5996.
Texte intégral
4
Mantelli, Luca, David Tucker et Mario Luigi Ferrari. « Dynamic Effect of Cold-Air Bypass Valve for Compressor Surge Recovery and Prevention in Fuel Cell Gas Turbine Hybrid Systems ». E3S Web of Conferences 113 (2019) : 02014. http://dx.doi.org/10.1051/e3sconf/201911302014.
Texte intégralRésumé :
A large volume between compressor and turbine is present in fuel cell gas turbine hybrid systems. The substantially larger compressor plenum volume modifies the dynamic behaviour of these systems, increasing the risk of compressor surge during transients and subsequent destruction of both turbomachinery and fuel cell components. Diverting part of the compressor inlet flow directly to the turbine inlet through a cold-air bypass valve, bypassing the fuel cell stack, has been proven to be an effective method to increase the surge margin during normal operation and also to recover the machine from fully developed surge. This study investigates the dynamic effect of different cold-air bypass valve opening/closing procedures, especially steps and ramps changing the valve fractional opening. This analysis was carried out with reference to the Hybrid Performance (Hyper) facility: a hybrid system emulated using hardware and a cyber-physical fuel cell system at the National Energy Technology Laboratory (NETL), U.S. Department of Energy (DOE). Simulations performed on a Matlab®-Simulink® dynamic model of the system based on Greitzer’s theory showed a different behaviour varying the valve fractional opening with steps or ramps. Many experimental tests were performed on the Hyper facility to confirm the trends obtained from the simulations results. From the outcomes of this study, it has been possible to determine how to maximize the surge recovery effect of the cold-air bypass valve opening and to minimize surge related risks during the valve closure.
5
Fang, Guo Cheng, Shi Da She, Zhen Qi Ye, Ji Zhang, Lai Wei, Qiang Wang, Xiang Qun Zhang et Yong Yun Ding. « Analysis and Application of Turbine Outages Kept Boiler of FCB Function in the Philippines Mariveles Power Plant ». Applied Mechanics and Materials 668-669 (octobre 2014) : 661–64. http://dx.doi.org/10.4028/www.scientific.net/amm.668-669.661.
Texte intégralRésumé :
This paper mainly introduces the system configuration of the Philippines Mariveles power plant, the difficulty and key points of the unit fast cut load (Fast Cut Back - FCB) control function were analyzed, and the boiler pressure control valve (Pressure Controlling Valve - PCV) discharge, turbine bypass opening coordination decrease pressure, integrate the override control, a fixed value servo and other control strategy, the possible problems in the process of test are sorting and analysis, and put forward effective solution, ensure the successful application of turbine outages kept boiler of FCB function, lay solid foundation for the safe and stable operation of the power grid.
6
Mazur, Z., G. Urquiza et R. Campos. « Improvement of the Turbine Main Stop Valves with Flow Simulation in Erosion by Solid Particle Impact CFD ». International Journal of Rotating Machinery 10, no 1 (2004) : 65–73. http://dx.doi.org/10.1155/s1023621x04000077.
Texte intégralRésumé :
The flow field in a steam turbine main stop valve bypass valve (MSVBV) has been investigated by means of CFD simulations. Because the entire flow to the turbine during start ups is carried by the MSVBV it is subject to serious solid particle erosion problems and requires frequent replacement to avoid the catastrophic damage which can occurred when the MSVBV skirt eroded through causing large pieces of metal to be carried directly into the turbine. For some of the most important geometric parameters of the MSVBV, design recommendation have been made.
7
Pugi, Luca, Emanuele Galardi, Carlo Carcasci et Nicola Lucchesi. « Hardware-in-the-loop testing of bypass valve actuation system : Design and validation of a simplified real time model ». Proceedings of the Institution of Mechanical Engineers, Part E : Journal of Process Mechanical Engineering 231, no 2 (3 août 2016) : 212–35. http://dx.doi.org/10.1177/0954408915589513.
Texte intégralRésumé :
During the start-up and shut-down phases of steam power plants many components are subjected to pressure and temperature transients that have to be carefully regulated both for safety and reliability reasons. For this reason, there is a growing interest in the optimization of turbine bypass controllers and actuators which are mainly used to regulate the plant during this kind of operations. In this work, a numerically efficient model for real-time simulation of a steam plant is presented. In particular, a modular Simulink™ library of components such as valves, turbines, and heaters has been developed. In this way, it is possible to easily assemble and customize models able to simulate different plants and operating scenarios. The code, which is implemented for a fixed, discrete step solver, can be easily compiled for a RT target (such as a Texas Instrument DSP) in order to be executed in real time on a low-cost industrial hardware. The proposed model has been used for quite innovative applications such as the development of a hardware-in-the-loop test rig of turbine bypass controllers and valve positioners. Preliminary experimental activities and results of the proposed test rig developed for Velan ABV are introduced and discussed.
8
Amano, R. S., G. R. Draxler et J. M. Golembiewski. « High-Pressure Steam Flow in Turbine Bypass Valve System Part 2 : Pipe Flow ». Journal of Propulsion and Power 18, no 3 (mai 2002) : 561–71. http://dx.doi.org/10.2514/2.5997.
Texte intégral
9
Kwon, W. C., G. R. Kim, S. C. Park et J. Y. Yoon. « Design of a tortuous path trim for a high-pressure turbine bypass valve ». Proceedings of the Institution of Mechanical Engineers, Part E : Journal of Process Mechanical Engineering 224, no 2 (4 février 2010) : 149–53. http://dx.doi.org/10.1243/09544089jpme316.
Texte intégral
10
Theotokatos, G., et N. P. Kyrtatos. « Investigation of a Large High- Speed Diesel Engine Transient Behavior Including Compressor Surging and Emergency Shutdown ». Journal of Engineering for Gas Turbines and Power 125, no 2 (1 avril 2003) : 580–89. http://dx.doi.org/10.1115/1.1559903.
Texte intégralRésumé :
The operation of a large high-speed engine under transient loading conditions was investigated, using a detailed simulation code in conjunction with a model capable of predicting compressor surging. Engine loadings were applied, which were considered dangerous for initiating compressor surging and cases where compressor surging could occur were identified. A means of avoiding compressor surging by opening a bypass valve connected between the compressor outlet and turbine inlet was examined. Finally, the case of engine abrupt stopping by rapidly closing the engine emergency shutdown valve, located downstream of the compressor, was also investigated.
11
Li, Hualei, Lei Shi et Kangyao Deng. « Research on the Power Recovery of Diesel Engines with Regulated Two-Stage Turbocharging System at Different Altitudes ». International Journal of Rotating Machinery 2014 (2014) : 1–10. http://dx.doi.org/10.1155/2014/209084.
Texte intégralRésumé :
Recovering the boost pressure is very important in improving the dynamic performance of diesel engines at high altitudes. A regulated two-stage turbocharging system is an adequate solution for power recovery of diesel engines. In the present study, the change of boost pressure and engine power at different altitudes was investigated, and a regulated two-stage turbocharging system was constructed with an original turbocharger and a matched low pressure turbocharger. The valve control strategies for boost pressure recovery, which formed the basis of the power recovery method, are presented here. The simulation results showed that this system was effective in recovering the boost pressure at different speeds and various altitudes. The turbine bypass valve and compressor bypass valve had different modes to adapt to changes in operating conditions. The boost pressure recovery could not ensure power recovery over the entire operating range of the diesel engine, because of variation in overall turbocharger efficiency. The fuel-injection compensation method along with the valve control strategies for boost pressure recovery was able to reach the power recovery target.
12
Traverso, Alberto, Aristide Massardo, Rory A. Roberts, Jack Brouwer et Scott Samuelsen. « Gas Turbine Assessment for Air Management of Pressurized SOFC/GT Hybrid Systems ». Journal of Fuel Cell Science and Technology 4, no 4 (9 juin 2006) : 373–83. http://dx.doi.org/10.1115/1.2714567.
Texte intégralRésumé :
This paper analyzes and compares transient and steady-state performance characteristics of different types of single-shaft turbo-machinery for controlling the air through a pressurized solid oxide fuel cell (SOFC) stack that is integrated into a SOFC/GT pressurized hybrid system. Analyses are focused on the bottoming part of the cycle, where the gas turbine (GT) has the role of properly managing airflow to the SOFC stack for various loads and at different ambient conditions. Analyses were accomplished using two disparate computer programs, which each modeled a similar SOFC/GT cycle using identical generic gas turbine performance maps. The models are shown to provide consistent results, and they are used to assess: (1) the influence of SOFC exhaust composition on expander behavior for on-design conditions, (2) the off-design performance of the bypass, bleed, and variable speed controls for various part-load conditions and for different ambient conditions; (3) the features of such controls during abrupt transients such as load trip and bypass/bleed valve failure. The results show that a variable speed microturbine is the best option for off-design operation of a SOFC/GT hybrid system. For safety measures a bleed valve provides adequate control of the system during load trip. General specifications for a radial GT engine for integration with a 550kW pressurized SOFC stack are identified, which allow operation under a wide range of ambient conditions as well as several different cycle configurations.
13
Ketata, Ahmed, Zied Driss et Mohamed Salah Abid. « Impact of the wastegate opening on radial turbine performance under steady and pulsating flow conditions ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 234, no 2-3 (27 mai 2019) : 652–68. http://dx.doi.org/10.1177/0954407019852494.
Texte intégralRésumé :
The present article attempts to describe the behavior of wastegated turbines under various steady and pulsating flow conditions. For this, meanline and one-dimensional numerical codes including appropriate modeling approaches for wastegated turbines have been developed with the FORTRAN language. These codes were validated against experiments with an established test rig at the National School of Engineers of Sfax. The discharge coefficient map of the wastegate was determined with a developed correlation built from experiments, and it was served as an input to the developed codes for interpolations during computation. This correlation is based on a two-dimensional non-linear dose-response fitting relationship instead of classical polynomial function which is one novelty of the article in addition to the one-dimensional modeling methodology. The normalized root mean square error (NRMSE) of both cycle-averaged efficiency and mass flow parameter (MFP) remains below 2% which confirms the validity of the proposed calculation approach. The results indicated a large deviation in the turbine performance under pulsating flow conditions compared to the steady state ones. The shape of the hysteresis loop of the turbine efficiency remains unchanged toward the variation of the wastegate valve angle at the same pulse frequency. The mass flow hystereses loop area is decreased by around 50% as the pulse frequency increases from 33 up to 133.33 Hz. An increase of less than 1% of the cycle-averaged efficiency has been reported when the bypass flow through the wastegate increases. The fluctuation of the efficiency is decreased by 1.5% when the wastegate valve becomes fully opened under the whole range of the pulse frequency.
14
Kwak, Hyo Seo, Hansaem Seong, Rivaldo Mersis Brilianto et Chul Kim. « Design of Laminated Seal for Triple Offset Butterfly Valve (350 °C) Used in Combined Cycle Power Plants ». Applied Sciences 9, no 15 (31 juillet 2019) : 3095. http://dx.doi.org/10.3390/app9153095.
Texte intégralRésumé :
In combined cycle power plants (CCPPs), the bypass butterfly valve is a key component to facilitate regulation of exhaust gas energy available at the turbine and to not produce too much boost pressure. The conventional damper valve causes leakage, back flow into the turbine, and damage of the blade, and the existing dual-layered seal with polytetrafluoroethylene (PTFE) and metal should be frequently replaced owing to its low durability and deterioration of mechanical properties under a high temperature. This study devised a triple offset butterfly valve with a new type of seal by alternatively laminating stainless steel and graphite to improve valve performance at the high temperature (350 °C). The slope angles of the seal contact surface to prevent friction were calculated using the mathematical models of the triple offset. Thermal-structure coupled analyses by varying the number of graphite and thickness were conducted, and the seven-layer model with the graphite thickness of 0.8 mm, which shows airtightness and smooth operation, was chosen. The contact stresses behaviors of the graphite at 350 °C and at −196 °C were investigated, and it was found that the graphite is in charge of improving driving performance of the disc at the high temperature and sealing performance at the cryogenic temperature. The performance tests and the field tests of the suggested model verified its performance at the working temperature.
15
Li, Nan, Ming chang Wang, Jian jun Guan et Guo dong Li. « Cause Analysis of Pressure Plate Breakage of Valve Limit Switch in Turbine Bypass System of Nuclear Power Plant ». IOP Conference Series : Materials Science and Engineering 220 (juillet 2017) : 012025. http://dx.doi.org/10.1088/1757-899x/220/1/012025.
Texte intégral
16
Liu, Zhong Chang, Xing Yuan, Jing Tian, Yong Qiang Han, Kai Bo Yu et Peng Kun Teng. « Effects of Injection Timing on Transient Performance of A Regulated Two-Stage Turbocharged Diesel Engine with Turbine Bypass Valve ». International Journal of Automotive Technology 19, no 5 (12 septembre 2018) : 783–94. http://dx.doi.org/10.1007/s12239-018-0075-3.
Texte intégral
17
ZAGANESCU, Nicolae-Florin, Constantin-Marcian GHEORGHE et Peter KALMUTCHI. « Original Romanian Research for a Rocket Engine with Multiple Combustion Chambers during 1940 - 1944 ». INCAS BULLETIN 12, no 1 (1 mars 2020) : 229–41. http://dx.doi.org/10.13111/2066-8201.2020.12.1.22.
Texte intégralRésumé :
The paper presents certain points of view regarding the history of Romanian rocket engines, during 1940-1944. Working independently of other scientists, during 1942 – 1944 the Romanian Nicolae Văideanu has invented and designed, independently of other researchers, a liquid fuel missile called UDOVILUL-V [3]. According to the design drawings, this missile was equipped with aerodynamically profiled propelling nozzles and was provided with a special alternator – distributor, the bypass valve adjusting the fuel components dosage in the two combustion chambers, in fuel tanks and pipes, while a special designed gas turbine was driving the centrifugal pumps and other mechanical equipment. Within his main patent the Romanian inventor has included the design of several components [2], [4], [5]. The technical solution of this outstanding design in rocketry development could provide 20kN thrust after 60 sec, enabling a speed of 3200 km/h [10].
18
Xia, Meng, et Fujun Zhang. « Application of Multi-Parameter Fuzzy Optimization to Enhance Performance of a Regulated Two-Stage Turbocharged Diesel Engine Operating at High Altitude ». Energies 13, no 17 (19 août 2020) : 4278. http://dx.doi.org/10.3390/en13174278.
Texte intégralRésumé :
Air intake and fuel supply conditions are the major factors that affect diesel engine performance at plateau. In a regulated two-stage turbocharged diesel engine, these parameters are reflected as the adjustment of fuel injection mass (mfuel), fuel injection advance angle, and bypass valve opening of a high-pressure stage (HP) turbine. Due to the strongly nonlinear nature and complexity of the diesel engine, it is difficult to find the proper parameter combinations. That is why a model-based optimization method is adopted in this paper. The simulation model of a six-cylinder two-stage turbocharged diesel engine is built on the GT-SUITE platform. According to the analysis of diesel engine operation characteristics at high altitude, a fuzzy optimization algorithm is proposed based on a fuzzy logic controller and is realized in a MATLAB/simulink (MATLAB 2014, Mathworks, Natick, MA, USA) environment. Joint optimization of air intake and fuel supply parameters is then performed on the GT-MATLAB co-simulation platform. Results show that engine torque at full load is significantly increased. At the full load point of 2100 r/min, engine power is increased from 256.5 to 319.6 kW, and brake specific fuel consumption (BSFC) is reduced from 243.1 to 222.3 g/(kW·h). Peak torque is increased from 1944.8 to 2173.2 N·m.
19
Guha, A. « Optimisation of aero gas turbine engines ». Aeronautical Journal 105, no 1049 (juillet 2001) : 345–58. http://dx.doi.org/10.1017/s0001924000012264.
Texte intégralRésumé :
Abstract A systematic methodology for the thermodynamic optimisation of civil bypass engines (turbofan or advanced propulsors) is presented, which would be useful for designing air-breathing engines based on “clean-sheet analysis”. The process starts with establishing an optimum specific thrust for the engine based on an economic analysis (installation constraints, noise regulations etc. also need to be considered). The task of the optimisation process is then to find the combination of optimum values of fan pressure ratio, overall pressure ratio, bypass ratio and turbine entry temperature concurrently that maximises overall efficiency at the fixed specific thrust. This procedure is quite different from the usual single-variable parametric performance studies which do not give proper optimum values and may involve large excursion in the value of the specific thrust unacceptable for a particular mission. Additionally, several, simple and explicit, analytical relations are derived here from fundamental principles, which perform well against numerical optimisation performed by a specialist computer program employing iterative and advanced search techniques. The analytical relations accelerate the optimisation process and offer physical insight. Present numerical computations with real gas properties have established new concepts in turbofan optimisation (for example, the existence of an optimum bypass ratio and optimum turbine entry temperature). The question of optimum jet velocity has been addressed. An analytical expression for the optimum jet velocity at a given bypass ratio has been derived which performs well against numerical optimisation results.
20
Joachim, Kurzke. « Starting and windmilling simulations using compressor and turbine maps ». Journal of the Global Power and Propulsion Society 7 (2 mars 2023) : 58–70. http://dx.doi.org/10.33737/jgpps/159372.
Texte intégralRésumé :
Starting and windmilling simulations with a normal gas turbine performance program require extended compressor and turbine maps which include sub-idle corrected speeds down to say 5–10% of the design value. During such simulations certain specific phenomena which are insignificant in the normal operating range between idle and full power must be considered. For example, while starting a low bypass ratio mixed flow turbofan, flow reversal in the bypass duct can occur. This paper illustrates a general understanding of what happens from when the starter is activated to when stabilized idle operation is reached. Operating lines in the compressor and turbine maps are predicted depending on starter torque, starter power, burner light-up and starter cut-off speed. It is explained why knowing combustor efficiency precisely is not required for that. Simulating engine starting and windmilling is not a magical art. The laws of physics still apply at these somewhat exotic operating conditions.
21
Filannino, Domenico, Michele Stefanizzi, Tommaso Capurso, Gabriella Balacco, Sergio M. Camporeale et Marco Torresi. « Bypass Control strategy of a Pump as Turbine in a Water Distribution Network for energy recovery ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012123. http://dx.doi.org/10.1088/1742-6596/2385/1/012123.
Texte intégralRésumé :
Abstract Water Distribution Networks (WDNs) are subject to leakages due to pipes aging, resulting in water and pressure losses. These issues are solved by installing Pressure Reduction Valves (PRVs) to decrease the pressure in WDNs. Depending on the application, PRVs can waste large amount of energy, hence the substitution of PRVs with Pumps used as Turbines (PaTs) can be a good compromise in terms of economic and technical aspects to reduce leakages and recover energy. Currently the share of PaT is not yet fully developed due to the certain technical challenges yet to be addressed, as providing an affordable control strategy closer to the real working conditions in a WDN. Hence, more experimental activities are required. For these reasons, in this work an experimental campaign was carried with the aim to investigate the behavior of a PaT according to a possible layout that could be embedded into a WDN. Firstly, the machine was characterized both in pump and turbine modes. Moreover, the machine working conditions limits have been analysed in terms of runaway and blocked-rotor curves. Then, turbine tests were carried out at constant speed with a typical hydraulic control scheme by means of a PRV installed in series to the PaT and a second one installed on a bypass. As a result, this analysis highlighted the feasibility to recover a consistent amount of hydraulic energy otherwise wasted under typical WDN daily pressure and flow rate patterns, with promising results in terms of the operating point control of the machine.
22
Arakelyan, Edik, Alexander Andryushin, Fedor Pashchenko, Sergey Mezin, Konstantin Andryushin et Anatoly Kosoy. « Increasing the reliability and manoeuvrability of the CCGT when operating in the variable part of the power consumption schedules by switching the CCGT steam turbine to the motor mode ». E3S Web of Conferences 216 (2020) : 01089. http://dx.doi.org/10.1051/e3sconf/202021601089.
Texte intégralRésumé :
The report is devoted to the problem of increasing the reliability and manoeuvrability of the CCGT when it operates in power control modes of the power system. The generalized results of research on improving the reliability and expanding the adjustment range of the PGU-450 based on the use of bypass steam distribution, reducing the duration of start-up operations and increasing the loading speed of the steam turbine and CCGT in general in the modes of CCGT power reserve during the night load gap by transferring the CCGT steam turbine to the motor mode when the CCGT operates in the condensation mode or in the heating mode according to the GTU-CHP scheme are presented. Additional advantages of the motor mode are noted: improved reliability of the steam turbine due to the elimination of cyclic temperature fluctuations of its steam inlet valves and vibrations in the last stages of the low-pressure cylinder and the possibility of operating the steam turbine generator in the synchronous compensator mode.
23
Ferrari, Mario L., Matteo Pascenti et Alessio Abrassi. « Test Rig for Emulation of Turbocharged SOFC Plants ». E3S Web of Conferences 113 (2019) : 02001. http://dx.doi.org/10.1051/e3sconf/201911302001.
Texte intégralRésumé :
This work is devoted to an emulator test rig designed for experimental analysis on SOFC-based plants pressurised by a turbocharger. The utilization of a turbocharger for SOFC pressurization aims to reduce the machine costs, due to the large mass production of this component. This emulator rig is an essential plant to perform tests on the component integration, dynamic operations, control system development and prevention of risky operative conditions (e.g. surge). These are essential issues to be solved before developing expensive complete prototypes and the related commercialization. This experimental plant is based on a pressure vessel for emulating the thermal (combustor and inert ceramic material) and fluid dynamic (the volume) responses. The vessel pressurisation is obtained with a turbocharger, where the exhaust flow operating in the turbine powers the compressor. The plant is also equipped with a recuperator and with different valves for control and flexibility reasons (bleed, compressor/turbine bypass, and recuperator bypass). Preliminary experimental results are included in this work focusing attention on the turbocharger choice and on the component constraints. In details, these are the necessary experiments for choosing the suitable machine for the rig (with a good surge margin for this component coupling).
24
Mund, F. C., et P. Pilidis. « Performance simulation of a high-bypass turbofan with a 2D representation of the intake and fan components ». Aeronautical Journal 112, no 1137 (novembre 2008) : 673–82. http://dx.doi.org/10.1017/s0001924000002645.
Texte intégralRésumé :
Abstract In conventional gas turbine performance simulation, engine components are represented by characteristics where the 3D properties of the flow fields are averaged providing key flow properties at the component interfaces. Even though a very efficient method, the simplification of 3D flows to an averaged value is not always desirable. In particular for high-bypass turbofan aero-engines, the fan generates significant pressure variations from hub to tip. These profiles are affected by the flow profile resulting from the intake where boundary layers introduce radial distortion patterns. This study investigates a performance simulation method where the intake and fan component of a two-shaft high-bypass turbofan are represented in an axi-symmetric 2D fashion. The intake was modelled using a commercial computational fluid dynamics tool. The remaining engine components were modelled using an in-house conventional gas turbine simulation tool with a radial representation of the fan. The coordinated application of both tools required an iterative data exchange, which is described in detail. The inclusion of the radial representation of fan and intake showed twice the effect on thrust per inlet loss at cruise conditions. It was therefore worth considering despite the significant numerical effort.
25
Kowalski, Mirosław, et Wojciech Kotlarz. « The Advantages of Using a Bleed of Air from Behind the Compressor and Supplying It Behind the Turbine in an Aircraft Engine ». Journal of KONBiN 50, no 3 (1 octobre 2020) : 381–94. http://dx.doi.org/10.2478/jok-2020-0067.
Texte intégralRésumé :
AbstractThe research paper discusses the advantages of using compressor downstream air partial bleed and supplying it downstream of the turbine, which was applied in a prototype of a “bypass” turbojet engine. The impact of such a solution on the value of achieved basic operating parameters of the engine was described, i.e., unit thrust and unit power consumption. The presented attempt to compare these parameters with the parameters achieved for a turbojet, single flow engine is very important; in the first case without air bleed, and in the second, with air bleed to the environment and with the parameters of a turbojet, turbofan engine with a jet mixer.
26
Khan, M. N., M. Osman, Abdulaziz R. Alharbi, Mohammad Rahimi Gorji et Ibrahim M. Alarifi. « Improving the efficiency of gas turbine-air bottoming combined cycle by heat exchangers and bypass control valves ». Physica Scripta 95, no 4 (11 février 2020) : 045701. http://dx.doi.org/10.1088/1402-4896/ab57cf.
Texte intégral
27
Ocana-Miguel, Antonio, Alfonso Gago-Calderon et Jose Ramon Andres-Diaz. « Experimental Outdoor Public Lighting Installation Powered by a Hydraulic Turbine Installed in the Municipal Water Supply Network ». Water 14, no 5 (23 février 2022) : 710. http://dx.doi.org/10.3390/w14050710.
Texte intégralRésumé :
Sustainability and energy prices make the use of energy obtained from renewable sources on an urban scale and for isolated local facilities necessary for municipal authorities. Moreover, when the demand of energy is at night, as for street lighting installations, the use of accumulative systems is necessary, which means a major drawback due to a short lifetime expectancy and high cost. The use of batteries can require more than 70% of the budget of these lighting systems and has a critical impact in the project. The problem to solve is finding different renewable energy sources that can produce energy throughout the day, especially during the night, at the same time at which it is consumed. As one of the competences of municipal authorities is water supply networks, this paper analyzes the use of energy recovery turbines within these installations as an alternative to photovoltaic generators. To study the viability and effectiveness of this alternative, the water flows available in the network of a medium-size municipality were monitored and analyzed in depth to assess the amount of recoverable energy. In addition, an energy recovery turbine (ERT) station was set up, installing a bypass around one of the pressure-reducing valves (PRV) of the installation where energy is dissipated without practical use. The results obtained imply that the system proposed has economical and technical viability, is reliable and guarantees full service in all the seasons’ conditions. Moreover, the needs of the energy storage capacity are much lower (~8%) than with solar panels.
28
Avdeev, S. V. « Mathematical model of turbofan engine weight estimation taking into account the engine configuration and size ». VESTNIK of Samara University. Aerospace and Mechanical Engineering 20, no 1 (20 avril 2021) : 5–13. http://dx.doi.org/10.18287/2541-7533-2021-20-1-5-13.
Texte intégralRésumé :
The paper presents a new correlation-regression model of estimating the turbofan engine weight considering the effect of the engines design schemes and dimensions. The purpose of this study was to improve the efficiency of the conceptual design process for aircraft gas turbine engines. Information on 183 modern turbofan engines was gathered using the available sources: publications, official websites, reference books etc. The statistic information included the values of the total engine air flow, the total turbine inlet gas temperature, the overall pressure ratio and the bypass ratio, as well as information on the structural layout of each engine. The engines and the related statistics were classified according to their structural layout and size. Size classification was based on the value of the compressor outlet air flow through the gas generator given by the parameters behind the compressor. Depending on the value of this criterion, the engines were divided into three groups: small-sized, medium-sized gas turbine engines, and large gas turbine engines. In terms of the structural layout, all engines were divided into three groups: turbofan engines without a mixing chamber, engines with a mixing chamber and afterburning turbofan engines. Statistical factors of the improved weight model were found for the respective groups of engines, considering their design and size. The coefficients of the developed model were determined by minimizing the standard deviations. Regression analysis was carried out to assess the quality of the developed model. The relative average error of approximation of the developed model was 8%, the correlation coefficient was 0,99, and the standard deviation was 10,2%. The model was found to be relevant and reliable according to Fisher's test. The obtained model can be used to assess the engine weight at the stage of conceptual design and for its optimization as part of an aircraft.
29
McIlroy, Hugh M., et Ralph S. Budwig. « The Boundary Layer Over Turbine Blade Models With Realistic Rough Surfaces ». Journal of Turbomachinery 129, no 2 (1 février 2005) : 318–30. http://dx.doi.org/10.1115/1.2218572.
Texte intégralRésumé :
Results are presented of extensive boundary layer measurements taken over a flat, smooth plate model of the front one-third of a turbine blade and over the model with an embedded strip of realistic rough surface. The turbine blade model also included elevated freestream turbulence and an accelerating freestream in order to simulate conditions on the suction side of a high-pressure turbine blade. The realistic rough surface was developed by scaling actual turbine blade surface data provided by U.S. Air Force Research Laboratory. The rough patch can be considered to be an idealized area of distributed spalls with realistic surface roughness. The results indicate that bypass transition occurred very early in the flow over the model and that the boundary layer remained unstable (transitional) throughout the entire length of the test plate. Results from the rough patch study indicate the boundary layer thickness and momentum thickness Reynolds numbers increased over the rough patch and the shape factor increased over the rough patch but then decreased downstream of the patch. It was also found that flow downstream of the patch experienced a gradual retransition to laminar-like behavior but in less time and distance than in the smooth plate case. Additionally, the rough patch caused a significant increase in streamwise turbulence intensity and normal turbulence intensity over the rough patch and downstream of the patch. In addition, the skin friction coefficient over the rough patch increased by nearly 2.5 times the smooth plate value. Finally, the rough patch caused the Reynolds shear stresses to increase in the region close the plate surface.
30
Yang, Jin Sik, Jeong L. Sohn et Sung Tack Ro. « Performance characteristics of part-load operations of a solid oxide fuel cell/gas turbine hybrid system using air-bypass valves ». Journal of Power Sources 175, no 1 (janvier 2008) : 296–302. http://dx.doi.org/10.1016/j.jpowsour.2007.09.074.
Texte intégral
31
Ryzhov, Oleg S., et Sergey V. Timofeev. « Interaction of a potential vortex with a local roughness on a smooth surface ». Journal of Fluid Mechanics 287 (25 mars 1995) : 21–58. http://dx.doi.org/10.1017/s002211209500084x.
Texte intégralRésumé :
Disturbances generated by a potential vortex moving past a small hump or dent on the otherwise smooth flat plate are considered. Features peculiar to this problem derive from the fact that the vortex is stuck with a fixed fluid particle; hence the nonlinear dependence of the pressure on the induced velocity field ensues even if the vortex intensity tends to zero. Formulation of the problem on a flow in the viscous wall sublayer given in canonical variables involves four similarity parameters for any particular shape of a roughness. The parallels between the process at hand and sound scattering from a boundary layer with a small obstacle at the bottom are indicated. Results from numerical integration of the boundary-value problem posed allow us to trace the evolution of the wave-packet structure depending on the potential vortex intensity. Overlapping of the peak wings and formation of an almost continuous spectrum in the Fourier decomposition of the signal serve as a guide for explaining the explosive development of the wave packet as distinct from the Tollmien–Schlichting wavetrain that has been registered experimentally.The theory developed is applied to discussing the so-called bypass mode of transition provoked by external turbulence. Special emphasis is laid on flows in gas turbine engines where bypass transition plays a dominant role owing to extremely high free-stream turbulence levels.
32
Sciatti, F., P. Tamburrano, P. De Palma, E. Distaso et R. Amirante. « Detailed simulations of an aircraft fuel system by means of Simulink ». Journal of Physics : Conference Series 2385, no 1 (1 décembre 2022) : 012033. http://dx.doi.org/10.1088/1742-6596/2385/1/012033.
Texte intégralRésumé :
Abstract The fuel system is one of the most important and complex parts of aircraft, being tasked with suppling the correct quantity of fuel to the aircraft engine during all operative conditions, from flight to ground operation. It must operate efficiently in any condition to guarantee safety and reliability. A fuel system for kerosene-based fuels (i.e., jet fuels) is a combination of hydraulic components, namely, tanks, pumps, bypass valves, safety valves, servovalves. The aim of this paper is to provide an accurate simulation model of an entire fuel system for gas turbine (turboprop and turbofan) engines, which can be used by manufacturers and researchers to evaluate the performance of the fuel system under different operating conditions for given components or to select the geometries of the components to obtain specific performance levels. The numerical code is developed in the Simulink environment, which is a software package widely used in industry. A detailed description of the model is provided in this paper, and results under specific operating conditions are shown and discussed. The power consumption of the system is assessed as well, with indication of the main sources of losses, which will be useful for current EU projects aimed at reducing the power consumption of aircraft.
33
Matsuura, Kazuo, Kotaro Matsui et Naoki Tani. « Effects of free-stream turbulence on the global pressure fluctuation of compressible transitional flows in a low-pressure turbine cascade ». International Journal of Numerical Methods for Heat & ; Fluid Flow 28, no 5 (8 mai 2018) : 1187–202. http://dx.doi.org/10.1108/hff-06-2017-0253.
Texte intégralRésumé :
Purpose This paper aims to investigate global pressure fluctuations in compressible transitional flows in a low-pressure turbine cascade because of variations in the free-stream turbulence and its interaction with the boundary layers. Design/methodology/approach Transition process resolving numerical simulations are performed with different types of inflow turbulence. The unsteady three-dimensional fully compressible Navier–Stokes equations are solved using a sixth-order compact difference and a tenth-order filtering method. First, simulations of both K-regime and bypass transitions are conducted for a flat plate boundary layer to validate the use of the filter in computing different transition routes. Second, computations of the cascade flows are conducted. Cases of no free-stream turbulence, isotropic free-stream turbulence of 5 per cent and wakes from an upstream cylinder are compared. For wakes, variations in wake trajectory depending on the cylinder blade relative position are also taken into account. Findings The different transition routes are successfully reproduced by the present method even with strong filtering. When feedback phenomena occur near the trailing edge, high-frequency oscillations dominate in the flow field. Low-frequency oscillations become dominant when the blade boundary layer becomes turbulent. Thus, the effects of the free-stream turbulence and its interaction with the boundary layer appear as changes in the global pressure fluctuation. Originality/value The free-stream turbulence qualitatively affects global pressure fluctuations, which become a medium to convey boundary-layer information away from the cascade.
34
Гольцов, Анатолий Сергеевич, et Hung Manh Tran. « Дослідження цифровий адаптивної системи повороту лопаток направляючого апаратів осьового компресора ». Aerospace technic and technology, no 4sup2 (27 août 2021) : 79–86. http://dx.doi.org/10.32620/aktt.2021.4sup2.10.
Texte intégralRésumé :
In the simplest cases, P-, PI- and PID-controllers with rigid (unchanged) parameter settings are used to control technological processes. If the mathematical model of the control object contains unknown disturbing influences and parameters that change during the control process, then a digital control system with a learning model should be used. The tasks of control, analysis and modeling of various processes and systems are solved using their mathematical models. The choice of a model is dictated by the conditions of implementation and the requirement of adequacy. The problem of developing control algorithms under uncertainty occupies one of the central places in modern control theory. To solve the arising problems of structural and parametric identification, as a rule, methods, and algorithms of the theory of adaptive control systems are used. The application of the principles of adaptation allows to ensure high accuracy of modeling with a significant change in the dynamic properties of the system under study, to unify individual subsystems and their blocks; reduce the development and debugging time of the system. This article discusses the problem of studying a digital adaptive system for turning the blades of guide apparatus (GA) of an axial compressor of gas turbine engines (GTE). The aim of the study is to increase the efficiency of the control system for turning the blades of the GA using a digital adaptive system. The gas-dynamic stability of the GTE axial compressor under changes in external conditions and engine throttling is provided by air bypass and turning the blades of the first and last compressor stages. The statement of the problem of synthesis of the system of adaptive control of the rotation of the blades of the GA compressor of the gas turbine engine is carried out. A mathematical model of the ACS in the canonical form “model of the system in the state space” and an algorithm for turning the blades of the GA using an adaptive PI-controller have been developed. Simulation modeling of ACS was carried out using the Matlab / Simulink software package. When implementing an adaptive PI-controller, the pressure deviation downstream of the compressor stage from the required value is reduced to 0.4 %.
35
Pachidis, Vassilios, Pericles Pilidis, Fabien Talhouarn, Anestis Kalfas et Ioannis Templalexis. « A Fully Integrated Approach to Component Zooming Using Computational Fluid Dynamics ». Journal of Engineering for Gas Turbines and Power 128, no 3 (1 mars 2004) : 579–84. http://dx.doi.org/10.1115/1.2135815.
Texte intégralRésumé :
Background . This study focuses on a simulation strategy that will allow the performance characteristics of an isolated gas turbine engine component, resolved from a detailed, high-fidelity analysis, to be transferred to an engine system analysis carried out at a lower level of resolution. This work will enable component-level, complex physical processes to be captured and analyzed in the context of the whole engine performance, at an affordable computing resource and time. Approach. The technique described in this paper utilizes an object-oriented, zero-dimensional (0D) gas turbine modeling and performance simulation system and a high-fidelity, three-dimensional (3D) computational fluid dynamics (CFD) component model. The work investigates relative changes in the simulated engine performance after coupling the 3D CFD component to the 0D engine analysis system. For the purposes of this preliminary investigation, the high-fidelity component communicates with the lower fidelity cycle via an iterative, semi-manual process for the determination of the correct operating point. This technique has the potential to become fully automated, can be applied to all engine components, and does not involve the generation of a component characteristic map. Results. This paper demonstrates the potentials of the “fully integrated” approach to component zooming by using a 3D CFD intake model of a high bypass ratio turbofan as a case study. The CFD model is based on the geometry of the intake of the CFM56-5B2 engine. The high-fidelity model can fully define the characteristic of the intake at several operating condition and is subsequently used in the 0D cycle analysis to provide a more accurate, physics-based estimate of intake performance (i.e., pressure recovery) and hence, engine performance, replacing the default, empirical values. A detailed comparison between the baseline engine performance (empirical pressure recovery) and the engine performance obtained after using the coupled, high-fidelity component is presented in this paper. The analysis carried out by this study demonstrates relative changes in the simulated engine performance larger than 1%. Conclusions. This investigation proves the value of the simulation strategy followed in this paper and completely justifies (i) the extra computational effort required for a more automatic link between the high-fidelity component and the 0D cycle, and (ii) the extra time and effort that is usually required to create and run a 3D CFD engine component, especially in those cases where more accurate, high-fidelity engine performance simulation is required.
36
Yang, Mingyang, Lei Pan, Mengying Shu, Kangyao Deng, Zhanming Ding et Yonghai Tian. « Aerodynamic interaction of turbines in a regulated two-stage turbocharging system ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering, 9 décembre 2021, 095440702110647. http://dx.doi.org/10.1177/09544070211064738.
Texte intégralRésumé :
Two-stage turbocharging becomes prevailing in internal combustion engines due to its advantage of flexibility of boosting for the variation of operational conditions. Two turbochargers are closely coupled by engine manifolds in the system especially under the requirement of compactness. This paper studies the influence of the interaction of two turbines in a two-stage turbocharging system on the performance. Results show that the performance of low-pressure turbine is highly sensitive to the stage interaction. Specifically, compared with the cases without interaction, the efficiency of low-pressure turbine increases maximumly by 2.8% when the bypass valve is closed, but reduces drastically by 7.5% when the valve is open. Detailed flow analysis shows that the combined results of swirling flow from the high-pressure turbine and the Dean vortex caused by the manifold elbow result in the alleviation of entropy generation in the turbine rotor. However, when the bypass valve is open, interaction of the swirling flow with the injected bypass flow results in strong secondary flow in the volute and distorted inlet flow condition for the rotor, leading to the enhancement of entropy generation in low-pressure turbine. The study provides valuable insights into turbine performance in a two-stage turbocharging system, which can be used for the modeling and optimization of multi-stage turbocharging systems.
37
Pezzini, Paolo, Sue Celestin et David Tucker. « Control Impacts of Cold-Air Bypass on Pressurized Fuel Cell Turbine Hybrids ». Journal of Fuel Cell Science and Technology 12, no 1 (1 février 2015). http://dx.doi.org/10.1115/1.4029083.
Texte intégralRésumé :
A pressure drop analysis for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle, implemented through the hybrid performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide means of evaluating risk mitigation strategies. The cold-air bypass in the Hyper facility directs compressor discharge flow to the turbine inlet duct, bypassing the fuel cell, and exhaust gas recuperators in the system. This valve reduces turbine inlet temperature while reducing cathode airflow, but significantly improves compressor surge margin. Regardless of the reduced turbine inlet temperature as the valve opens, a peak in turbine efficiency is observed during characterization of the valve at the middle of the operating range. A detailed experimental analysis shows the unusual behavior during steady state and transient operation, which is considered a key point for future control strategies in terms of turbine efficiency optimization and cathode airflow control.
38
« Analysis of Flow Field in a Steam Turbine Bypass Valve ». Journal of Fluid Machinery 9, no 4 (1 août 2006) : 36–42. http://dx.doi.org/10.5293/kfma.2006.9.4.036.
Texte intégral
39
Emami, Tooran, Alex Tsai et David Tucker. « Apply Robust Proportional Integral Derivative Controller to a Fuel Cell Gas Turbine ». Journal of Electrochemical Energy Conversion and Storage 15, no 2 (13 mars 2018). http://dx.doi.org/10.1115/1.4038635.
Texte intégralRésumé :
Abstract The performance of a 300 kW solid oxide fuel cell gas turbine (SOFC-GT) pilot power plant simulator is evaluated by applying a set of robust proportional-integral-derivative (PID) controllers that satisfy time delay and gain uncertainties of the SOFC-GT system. The actuators are a fuel valve (FV) that models the fuel cell (FC) thermal exhaust, and a cold-air (CA) valve which bypasses airflow rate from the FC cathode. The robust PID controller results for the upper and lower boundary of uncertain gains are presented first, followed by a design for the upper and lower boundary of uncertain time delays process for both, FV and CA bypass valves. The final design incorporates the combined uncertain gain and the time delay modeling for the upper and lower boundary of both actuators. This multiple-input multiple-output technique is beneficial to plants having a wide range of operation and a strong parameter interaction. The practical implementation of the PID controllers and the set point responses are presented through simulation in the matlab/simulink environment.
40
Zaccaria, Valentina, David Tucker et Alberto Traverso. « Cold-Air Bypass Characterization for Thermal Management of Fuel Cell Gas Turbine Hybrids ». Journal of Engineering for Gas Turbines and Power 139, no 6 (1 février 2017). http://dx.doi.org/10.1115/1.4035396.
Texte intégralRésumé :
The effect of cathode airflow variation on the dynamics of a fuel cell gas turbine hybrid system was evaluated using a cyber-physical emulator. The coupling between cathode airflow and other parameters, such as turbine speed or pressure, was analyzed comparing the results at fixed and variable speed. In particular, attention was focused on fuel cell temperatures and gradients: cathode airflow, which is generally employed for thermal management of the stack, was varied by manipulating a cold-air bypass. A significant difference was observed in the two cases in terms of turbine inlet, exhaust gas, cathode inlet, and average cell temperatures. When the turbine speed was held constant, a change in cathode airflow resulted in a strong variation in cathode inlet temperature, while average cell temperature was not significantly affected. The opposite behavior was observed at variable speed. The system dynamics were analyzed in detail in order to explain this difference. Open-loop response was analyzed in this work for its essential role in system identification. However, a significant difference was observed between fixed and variable speed cases, because of the high coupling between turbine speed and cathode airflow. These results can give a helpful insight of system dynamics and control requirements. Cold-air valve bypass position also showed a strong effect on surge margin and pressure dynamics in both cases.
41
Kahlert, Steffen, et Hartmut Spliethoff. « Investigation of Different Operation Strategies to Provide Balance Energy With an Industrial Combined Heat and Power Plant Using Dynamic Simulation ». Journal of Engineering for Gas Turbines and Power 139, no 1 (16 août 2016). http://dx.doi.org/10.1115/1.4034184.
Texte intégralRésumé :
Intermittency of renewable electricity generation poses a challenge to thermal power plants. While power plants in the public sector see a decrease in operating hours, the utilization of industrial power plants is mostly unaffected because process steam has to be provided. This study investigates to what extent the load of a combined heat and power (CHP) plant can be reduced while maintaining a reliable process steam supply. A dynamic process model of an industrial combined CHP plant is developed and validated with operational data. The model contains a gas turbine (GT), a single pressure heat recovery system generator (HRSG) with supplementary firing and an extraction condensing steam turbine. Technical limitations of the gas turbine, the supplementary firing, and the steam turbine constrain the load range of the plant. In consideration of these constraints, different operation strategies are performed at variable loads using dynamic simulation. A simulation study shows feasible load changes in 5 min for provision of secondary control reserve (SCR). The load change capability of the combined cycle plant under consideration is mainly restricted by the water–steam cycle. It is shown that both the low pressure control valve (LPCV) of the extraction steam turbine and the high pressure bypass control valve are suitable to ensure the process steam supply during the load change. The controllability of the steam turbine load and the process stability are sufficient as long as the supplementary is not reaching the limits of the operating range.
42
Kitzmiller, Kyle, et Fletcher Miller. « Effect of Variable Guide Vanes and Natural Gas Hybridization for Accommodating Fluctuations in Solar Input to a Gas Turbine ». Journal of Solar Energy Engineering 134, no 4 (6 août 2012). http://dx.doi.org/10.1115/1.4006894.
Texte intégralRésumé :
In recent years, several prototype solar central receivers have been experimentally demonstrated to produce high temperature and high pressure gas capable of driving a gas turbine engine. While these prototype receivers are generally small (<1 MWth), advancements in this technology will allow for the development of solar powered gas turbine engines at a commercial level (sizes of at least several megawatts electric (MWe)). The current paper analyzes a recuperated solar powered gas turbine engine, and addresses engine considerations, such as material limitations, as well as the variable nature of solar input. In order to compensate for changes in solar input, two operational strategies are identified and analyzed. The first is hybridization, meaning the solar input is supplemented via the combustion of fossil fuels. Hybridization often allows for an increase in net power and efficiency by adding heat during periods of low solar thermal input. An alternative strategy is to make use of variable guide vanes on the compressor of the gas turbine engine, which schedule to change the air flow rate into the system. By altering the mass flow rate of air, and assuming a fixed level of heat addition, the operating temperature of the engine can be controlled to maximize power or efficiency. The paper examines how to combine hybridization with variable guide vane operation to optimize gas turbine performance over a wide range of solar thermal input, from zero solar input to solar-only operation. A large material constraint is posed by the combustor, and to address this concern two alternative strategies—one employing a bypass valve and the other a combustor modified to allow higher temperature inlet air—are presented. Combustor modifications could include new materials and/or increased cooling air. The two strategies (bypass versus no bypass) are compared on a thermodynamic basis. It is found that it is possible to operate the gas turbine across the entire range without a significant drop in performance in either design through judicious adjustment of the vanes, though both approaches yield different results for certain ranges of solar input. Finally, a yearly assessment of solar share and thermodynamic performance is presented for a 4.3 MWe gas turbine to identify the overall benefits of the operational strategies. The annualized thermodynamic performance is not appreciably different for the two strategies, so that other factors such as mechanical design, operational issues, economics, etc. must be used to decide the optimal approach.
43
Zhou, Nana, Chen Yang et David Tucker. « Evaluation of Cathode Air Flow Transients in a SOFC/GT Hybrid System Using Hardware in the Loop Simulation ». Journal of Fuel Cell Science and Technology 12, no 1 (1 février 2015). http://dx.doi.org/10.1115/1.4028950.
Texte intégralRésumé :
Thermal management in the fuel cell component of a direct fired solid oxide fuel cell gas turbine (SOFC/GT) hybrid power system can be improved by effective management and control of the cathode airflow. The disturbances of the cathode airflow were accomplished by diverting air around the fuel cell system through the manipulation of a hot-air bypass valve in open loop experiments, using a hardware-based simulation facility designed and built by the U.S. Department of Energy, National Energy Technology Laboratory (NETL). The dynamic responses of the fuel cell component and hardware component of the hybrid system were studied in this paper.
44
Pezzini, Paolo, David Tucker et Alberto Traverso. « Avoiding Compressor Surge During Emergency Shutdown Hybrid Turbine Systems ». Journal of Engineering for Gas Turbines and Power 135, no 10 (30 août 2013). http://dx.doi.org/10.1115/1.4025036.
Texte intégralRésumé :
A new emergency shutdown procedure for a direct-fired fuel cell turbine hybrid power system was evaluated using a hardware-based simulation of an integrated gasifier/fuel cell/turbine hybrid cycle (IGFC), implemented through the Hybrid Performance (Hyper) project at the National Energy Technology Laboratory, U.S. Department of Energy (NETL). The Hyper facility is designed to explore dynamic operation of hybrid systems and quantitatively characterize such transient behavior. It is possible to model, test, and evaluate the effects of different parameters on the design and operation of a gasifier/fuel cell/gas turbine hybrid system and provide a means of quantifying risk mitigation strategies. An open-loop system analysis regarding the dynamic effect of bleed air, cold air bypass, and load bank is presented in order to evaluate the combination of these three main actuators during emergency shutdown. In the previous Hybrid control system architecture, catastrophic compressor failures were observed when the fuel and load bank were cut off during emergency shutdown strategy. Improvements were achieved using a nonlinear fuel valve ramp down when the load bank was not operating. Experiments in load bank operation show compressor surge and stall after emergency shutdown activation. The difficulties in finding an optimal compressor and cathode mass flow for mitigation of surge and stall using these actuators are illustrated.
45
Khan, M. N., Tawfeeq Abdullah Alkanhal, Jihen Majdoubi et Iskander Tlili. « Performance enhancement of regenerative gas turbine : air bottoming combined cycle using bypass valve and heat exchanger—energy and exergy analysis ». Journal of Thermal Analysis and Calorimetry, 21 mars 2020. http://dx.doi.org/10.1007/s10973-020-09550-w.
Texte intégral
46
Greyvenstein, Gideon P. « The Application of System CFD to the Design and Optimization of High-Temperature Gas-Cooled Nuclear Power Plants ». Journal of Engineering for Gas Turbines and Power 130, no 3 (28 mars 2008). http://dx.doi.org/10.1115/1.2835057.
Texte intégralRésumé :
The objective of this paper is to model the steady-state and dynamic operation of a pebble-bed-type high temperature gas-cooled reactor power plant using a system computational fluid dynamics (CFD) approach. System CFD codes are 1D network codes with embedded 2D or even 3D discretized component models that provide a good balance between accuracy and speed. In the method presented in this paper, valves, orifices, compressors, and turbines are modeled as lumped or 0D components, whereas pipes and heat exchangers are modeled as 1D discretized components. The reactor is modeled as 2D discretized system. A point kinetics neutronic model will predict the heat release in the reactor. Firstly, the layout of the power conversion system is discussed together with the major plant parameters. This is followed by a high level description of the system CFD approach together with a description of the various component models. The code is used to model the steady-state operation of the system. The results are verified by comparing them with detailed cycle analysis calculations performed with another code. The model is then used to predict the net power delivered to the shaft over a wide range of speeds from zero to full speed. This information is used to specify parameters for a proportional-integral-derivative controller that senses the speed of the power turbine and adjusts the generator power during the startup of the plant. The generator initially acts as a motor that drives the shaft and then changes over to a generator load that approaches the design point value as the speed of the shaft approaches the design speed. A full startup simulation is done to demonstrate the behavior of the plant during startup. This example demonstrates the application of a system CFD code to test control strategies. A load rejection example is considered where the generator load is suddenly dropped to zero from a full load condition. A controller senses the speed of the low pressure compressor/low pressure turbine shaft and then adjusts the opening of a bypass valve to keep the speed of the shaft constant at 60rps. The example demonstrates how detailed information on critical parameters such as turbine and reactor inlet temperatures, maximum fuel temperature, and compressor surge margin can be obtained during operating transients. System CFD codes is a powerful design tool that is indispensable in the design of complex power systems such as gas-cooled nuclear power plants.
47
Mueller, Fabian, Brian Tarroja, James Maclay, Faryar Jabbari, Jacob Brouwer et Scott Samuelsen. « Design, Simulation and Control of a 100 MW-Class Solid Oxide Fuel Cell Gas Turbine Hybrid System ». Journal of Fuel Cell Science and Technology 7, no 3 (11 mars 2010). http://dx.doi.org/10.1115/1.3207868.
Texte intégralRésumé :
A 100 MW-class planar solid oxide fuel cell synchronous gas turbine hybrid system has been designed, modeled, and controlled. The system is built of 70 functional fuel cell modules, each containing 10 fuel cell stacks, a blower to recirculate depleted cathode air, a depleted fuel oxidizer, and a cathode inlet air recuperator with bypass. The recuperator bypass serves to control the cathode inlet air temperature, while the variable speed cathode blower recirculates air to control the cathode air inlet temperature. This allows for excellent fuel cell thermal management without independent control of the gas turbine, which at this scale will most likely be a synchronous generator. In concept the demonstrated modular design makes it possible to vary the number of cells controlled by each fuel valve, power electronics module, and recirculation blower, so that actuators can adjust to variations in the hundreds of thousands of fuel cells contained within the 100 MW hybrid system for improved control and reliability. In addition, the modular design makes it possible to take individual fuel cell modules offline for maintenance while the overall system continues to operate. Parametric steady-state design analyses conducted on the system reveal that the overall fuel-to-electricity conversion efficiency of the current system increases with increased cathode exhaust recirculation. To evaluate and demonstrate the conceptualized design, the fully integrated system was modeled dynamically in MATLAB-SIMULINK®. Simple proportional feedback with steady-state feed-forward controls for power tracking, thermal management, and stable gas turbine operation were developed for the system. Simulations of the fully controlled system indicate that the system has a high efficiency over a large range of operating conditions, decent transient load following capability, fuel and ambient temperature disturbance rejection, and the capability to operate with a varying number of fuel cell modules. The efforts here build on prior work and combine the efforts of system design, system operation, component performance characterization, and control to demonstrate hybrid transient capability in large-scale coal synthesis gas-based applications through simulation. Furthermore, the use of a modular fuel cell system design, the use of blower recirculation, and the need for integrated system controls are verified.
48
Cui, Yi, Zhilong Hu, Kangyao Deng et Qifu Wang. « Miller-Cycle Regulatable, Two-Stage Turbocharging System Design for Marine Diesel Engines ». Journal of Engineering for Gas Turbines and Power 136, no 2 (1 novembre 2013). http://dx.doi.org/10.1115/1.4025486.
Texte intégralRésumé :
The increasingly stringent NOx emission regulations of the International Marine Organization (IMO) have demanded new design concepts and architectures for diesel engines. The Miller cycle, which reduces the in-cylinder combustion temperature by reducing the effective compression ratio, is the principal measure used for reducing NOx specific emissions; however, this is at the cost of volumetric efficiency and engine power. Therefore, it is essential to combine the Miller cycle with a highly boosted turbocharging system, two-stage turbocharging for example, to recover the power. While much work has been done in the development of Miller-cycle regulatable two stage turbocharging system for marine diesel engines, there are nonetheless few, if any, thorough discussions on system optimization and performance comparison. This study presents a theoretical optimization design process for a Miller-cycle regulatable, two-stage turbocharging system for marine diesel engines. First, the different scenarios and regulation methods of two-stage turbocharging systems are compared according to the system efficiency and equivalent turbine flow characteristics. Then, a multizone combustion model based on a one-dimensional cycle simulation model is established and used for the optimization of valve timings according to the IMO NOx emission limits and fuel efficiencies. The high- and low-stage turbochargers are selected by an iterative matching method. Then, the control strategies for the boost air and high-stage turbine bypass valves are also studied. As an example, a Miller-cycle regulatable, two-stage turbocharging system is designed for a highly boosted high-speed marine diesel engine. The results show that NOx emissions can be reduced by 30% and brake specific fuel consumption (BSFC) can also be improved by a moderate Miller cycle combined with regulatable two-stage turbocharging.
49
Ferrari, Mario L., Matteo Pascenti, Loredana Magistri et Aristide F. Massardo. « Hybrid System Test Rig : Start-up and Shutdown Physical Emulation ». Journal of Fuel Cell Science and Technology 7, no 2 (5 janvier 2010). http://dx.doi.org/10.1115/1.3176663.
Texte intégralRésumé :
The University of Genoa (TPG) has designed and developed an innovative test rig for high temperature fuel cell hybrid system physical emulation. It is based on the coupling of a modified commercial 100 kW recuperated micro gas turbine to a special modular volume designed for the experimental analysis of the interaction between different dimension fuel cell stacks and turbomachines. This new experimental approach that generates reliable results as a complete test rig also allows investigation of high risk situations with more flexibility without serious and expensive consequences to the equipment and at a very low cost compared with real hybrid configurations. The rig, developed with the support of the European Integrated Project “FELICITAS,” is under exploitation and improvement in the framework of the new European Integrated Project “LARGE-SOFC” started in January 2007. The layout of the system (connecting pipes, valves, and instrumentation) was carefully designed to minimize the pressure loss between compressor outlet and turbine inlet to have the highest plant flexibility. Furthermore, the servocontrolled valves are useful for performing tests at different operative conditions (i.e., pressures, temperatures, and pressure losses), focusing the attention on surge and thermal stress prevention. This work shows the preliminary data obtained with the machine connected to the volume for the test rig safe management to avoid surge or excessive stress, especially during the critical operative phases (i.e., start-up and shutdown). Finally, the attention is focused on the valve control system developed to emulate the start-up and shutdown phases for high temperature fuel cell hybrid systems. It is necessary to manage the flows in the connecting pipes, including an apt recuperator bypass, to perform a gradual heating up and cooling down as requested during these phases. It is an essential requirement to avoid thermal stress for the fuel cell stack. For this reason, during the start-up, the volume is gradually heated by the compressor outlet flow followed by a well managed recuperator outlet flow and vice versa for the shutdown. Furthermore, operating with a constant rotational speed control system, the machine load is used to reach higher temperature values typical of these kinds of systems.
50
Liu, Ruilin, Zhongjie Zhang, Surong Dong et Guangmeng Zhou. « High-Altitude Matching Characteristic of Regulated Two-Stage Turbocharger With Diesel Engine ». Journal of Engineering for Gas Turbines and Power 139, no 9 (19 avril 2017). http://dx.doi.org/10.1115/1.4036283.
Texte intégralRésumé :
To improve engine power at high altitude, the regulated two-stage turbocharger (RTST) which was applied to different altitudes was developed by the authors. The working process model of heavy-duty common-rail diesel engine matched with RTST was built to study the regulating characteristic of variable geometry turbocharger (VGT) vane and both turbine bypass valves and also matching performance of RTST with engine at different altitudes. The control scheme of RTST at different altitudes and engine operating conditions was first put forward, and the optimal opening maps of VGT vane and both turbine bypass valves at different altitudes and engine operating conditions were obtained. The results show that the optimal openings of VGT vane and both turbine bypass valves decrease with increase of altitude, and the optimal opening range of VGT vane becomes narrower with increase of altitude. The operating points of both high-pressure (HP) and low-pressure (LP) compressors locate at high-efficiency region of each compressor map, respectively, and compressor efficiency exceeds 70% at altitude of 5500 m. The total boost pressure ratio increases with altitude and reaches the maximum value of 5.1 at altitude of 5500 m. Compared with single-stage turbocharged engine, the rated power, maximum torque, and torques at lower engine speed at altitude of 5500 m increase by 48.2%, 51%, and 65–121% separately, and the minimum fuel consumption decreases by 12.6%.