Academic literature on the topic 'Steam-gas cavity'
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Journal articles on the topic "Steam-gas cavity"
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Jowkar, Amin, Farhang Sereshki, and Mehdi Najafi. "Numerical simulation of UCG process with the aim of increasing calorific value of syngas." International Journal of Coal Science & Technology 7, no. 1 (December 19, 2019): 196–207. http://dx.doi.org/10.1007/s40789-019-00288-x.
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AbstractThe determination of operational parameters in the underground coal gasification (UCG) process should be considered in two aspects: first, the total coal in each UCG panel must be gasified and second, the calorific value of the produced gas should be acceptable. The main aim of this study is to present a model that meets these aspects and increasing the calorific value of syngas during this process. In order to achieve those aims, eight different increasing scenarios were devised for total gasification of coal per panel. These scenarios included: increasing oxygen injection rate (scenario 1), the amount of steam injection (scenario 2), operation time (scenario 3), cavity pressure (scenario 4), increase operation time and cavity pressure simultaneously (scenario 5), increase steam injection speed and oxygen injection rate simultaneously (scenario 6), increase in cavity pressure, operating time, steam injection rate and oxygen injection rate simultaneously (scenario 7) and also simultaneous increase in the operating time and steam injection rate (scenario 8). The results showed that for producing syngas with a higher calorific value, the following parameters had the most positive effects respectively: operation time, cavity pressure, steam injection rate and oxygen injection rate. Finally, the model validation was performed for the Centralia LBK-1 UCG pilot and the results showed that this model is very close to reality.
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Mallett, CW. "Environmental controls for underground coal gasification." Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy 232, no. 1 (August 2, 2017): 47–55. http://dx.doi.org/10.1177/0957650917723733.
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Effective environmental management of an underground coal gasification pilot has been demonstrated at Kogan in Queensland, Australia. It commenced with selection of a suitable site with a coal seam surrounded by impervious rocks that provided a gas seal for the gasifier and sufficient groundwater pressure to constrain lateral loss of gas and chemicals through coal fractures. Project infrastructure was specified to withstand the temperatures and pressures experienced during gasification and gas processing. During syngas production in the second gasifier, Panel 2, it was shown that all pyrolysis products of environmental concern were retained within the gasifier. This was achieved by maintaining continuous groundwater inflow into the gasifier cavity through control of the relative pressures of the gasifier and surrounding groundwater. In Panel 1, it was shown that when pyrolysis products migrated out of the cavity, they were quickly detected and by modifying relative pressures to increase groundwater inflow the original groundwater conditions were restored. Following production, the cavities were decommissioned and in Panel 2 steam cleaning of the cavity removed 92% of the chemical load from the cavity. As a result, relatively low concentrations of pyrolysis products remained in the cavity. Fate and transport modelling predicted that these products will not migrate into the regional groundwater and will naturally degrade within three decades.
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Ma, Xiao Xuan, Zeng He Li, Tij Je Cai, and Ya Zhen Liu. "Thermal Decomposition Dew Point Method for Determining the Trace Moisture in Ultra-Purity Ammonia." Advanced Materials Research 718-720 (July 2013): 571–75. http://dx.doi.org/10.4028/www.scientific.net/amr.718-720.571.
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This article introduced a fast and stable method on measuring the batches of trace moisture in ultra-purity ammonia gas .This method is based on ammonia decomposited reaction ,which occurs completely and irreversibly when ammonia is passed over nickel catalyst at high temperatures. While the trace water wapor passes though the catalyst unchanged. And the moisture of ammonia may be determined by measuring the dew point of the steam of hydrogen and nitrogen produced by decomposition of ammonia,combined with the trace oxygen content measured by GC,the content of trace moisture in ultra-purity ammonia gas can be got. Contrasted with Cavity Ring-down Spectroscopy (CRDS) and Infrared Absorption Spectroscopy (IR),Thermal Decomposition Dew Point method (TDDP) has high accuracy,good repeatability, stability and environmentally friendly.
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KIM, BUMJOON, and BYEONGSOO LIM. "EVALUATION OF CREEP-FATIGUE LIFE BY FRACTION OF CAVITY AREA." International Journal of Modern Physics B 20, no. 25n27 (October 30, 2006): 4237–42. http://dx.doi.org/10.1142/s021797920604115x.
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The components of power plant such as main steam pipe and gas turbines are operated under static and cyclic load conditions. As the period of static load increases, the service life of these components decreases. Generally, the increase of cyclic load results in fatigue damage and the increase of static load period results in the metallurgical degradation by the effect of creep. Under the creep-fatigue interaction, cavities cause rapid degradation of material and decreases the creep-fatigue life of high temperature components. In this paper, creep-fatigue tests were performed to investigate the relationship between the cavity and creep-fatigue life under various tensile hold times. Test materials were HAZ and base metal of P122 (12 Cr -2 W ) alloy weldment. The effect of hold times on the cavity damage was examined and the fraction of cavity area was analyzed. From the linear relationship of Fca (fraction of cavity area) and experimental life, a new parameter for life evaluation, Fca, was introduced and the creep-fatigue life was predicted by Fca. Good agreement was found between experimental and predicted life. Under the same hold time condition, the Fca of HAZ was greater than that of base metal while the creep-fatigue life of HAZ was shorter than that of base metal.
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Bayley, F. J., C. A. Long, and A. B. Turner. "Discs and Drums: The Thermo-Fluid Dynamics of Rotating Surfaces." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 207, no. 2 (March 1993): 73–81. http://dx.doi.org/10.1243/pime_proc_1993_207_103_02.
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This paper reviews long-term experimental and theoretical research programmes concerned with flow and heat transfer over the large rotating surfaces, commonly discs, often drums but sometimes conical, used to support the blades in turbomachinery. The account begins with a geometry found in turbomachinery from the oldest steam plant to the most modern gas turbine, in which a disc rotates near to a stationary, usually coaxial, member. The flow in the intervening ‘wheel-space’ is well understood, but external conditions can affect the extent and nature of ingress from the surrounding fluid. In the gas turbine this fluid is the mainstream hot gas, an inflow of which could have serious consequences, so that the study of ingress has become the principal subject of research for rotor-stator systems and recent work is fully reported here. In many turbo-machines, especially compressors, adjacent coaxial surfaces rotate together and thus enclose a cavity subject to unusual forces in which a wide range of flow regimes can obtain. The precise form depends largely on whether the cavity allows a net radial inflow or outflow of fluid or whether the only access and egress are from near the axis of the system, the so-called ‘axial through-flow’ case. Systems with a net radial flow, inward or outward, are well understood. In their absence, the flows are often four dimensional, varying with time and in the three space coordinates. Such regimes remain incompletely understood although recent congruence between experimental and theoretical studies is encouraging. Finally, attention is turned to surfaces nearer parallel than orthogonal to the axis of rotation, as in the drums used in older steam turbines and commonly in compressors. Here the main concern has been with the effect of stationary blading, where the close clearance between the blading and the rotating surface modifies the boundary layers and thus the friction and heat transfer on the latter.
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Jamel, Mahmood S., A. Abd Rahman, and A. H. Shamsuddin. "Novel integrations of molten salt cavity tubular solar central receiver with existing gas-fuelled conventional steam power plants." International Journal of Sustainable Energy 35, no. 1 (November 15, 2013): 21–32. http://dx.doi.org/10.1080/14786451.2013.858159.
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Eden, T. J., T. F. Miller, and H. R. Jacobs. "The Centerline Pressure and Cavity Shape of Horizontal Plane Choked Vapor Jets With Low Condensation Potential." Journal of Heat Transfer 120, no. 4 (November 1, 1998): 999–1007. http://dx.doi.org/10.1115/1.2825921.
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A study of plane, underexpanded, condensing vapor jets was undertaken using flash photography and a ventilated pressure probe. This study examined horizontal jets with much lower condensation driving potentials than have been previously studied. Photographic measurements of jet expansion angles, spread angles, cavity lengths, and cavity shapes were recorded and compared with numerical predictions using a parabolic, locally homogeneous flow model that had been modified to incorporate entrainment and condensation effects. When rendered dimensionless by the nozzle width rather than diameter, the plane condensation length agreed well with previously published round jet correlations for higher condensation driving potentials. At lower condensation driving potentials, the jets began to disperse, showing behavior similar to submerged air and energetic reacting vapor jets. Numerical predictions of condensation length were in good agreement over the entire range of measurement. Numerical predictions of vapor cavity shape were in reasonable agreement at higher condensation potentials but underpredicted the width of the vapor cavity at lower potentials. Pressure measurements showed the existence of periodic expansion/compression cells associated with underexpanded noncondensing gas jets. When these measurements were compared with similar measurements of air jets into quiescent water baths, the lengths of the initial steam vapor expansion/compression cells were substantially greater than those of the air jets, and the degree of pressure recovery over the cell length was substantially less.
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Jamel, Mahmood S., A. Abd Rahman, and A. H. Shamsuddin. "Repowering of existing AL-Hartha gas-fuelled conventional steam power plant with molten salt cavity tubular solar central receiver." Clean Technologies and Environmental Policy 16, no. 8 (March 25, 2014): 1661–74. http://dx.doi.org/10.1007/s10098-014-0740-9.
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Arup Kumar Biswas, Wasu Suksuwan, Khamphe Phoungthong, and Makatar Wae-hayee. "Effect Of Equivalent Ratio (ER) On the Flow and Combustion Characteristics in A Typical Underground Coal Gasification (UCG) Cavity." Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 86, no. 2 (August 24, 2021): 28–38. http://dx.doi.org/10.37934/arfmts.86.2.2838.
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Underground Coal Gasification (UCG) is thought to be the most favourable clean coal technology option from geological-engineering-environmental viewpoint (less polluting and high efficiency) for extracting energy from coal without digging it out or burning it on the surface. UCG process requires only injecting oxidizing agent (O2 or air with steam) as raw material, into the buried coal seam, at an effective ratio which regulates the performance of gasification. This study aims to evaluate the influence of equivalent ratio (ER) on the flow and combustion characteristics in a typical half tear-drop shape of UCG cavity which is generally formed during the UCG process. A flow modeling software, Ansys FLUENT is used to construct a 3-D model and to solve problems in the cavity. The boundary conditions are- (i) a mass-flow-inlet passing oxidizer (in this case, air) into the cavity, (ii) a fuel-inlet where the coal volatiles are originated and (iii) a pressure-outlet for flowing the product Syngas out of the cavity. A steady-state simulation has been run using k-? turbulence model. The mass flow rate of air varied according to an equivalent ratio (ER) of 0.16, 0.33, 0.49 and 0.82, while the fuel flow rate was fixed. The optimal condition of ER has been identified through observing flow and combustion characteristics, which looked apparently stable at ER 0.33. In general, the flow circulation mainly takes place around the ash-rubble pile. A high temperature zone is found at the air-releasing point of the injection pipe into the ash-rubble pile. This study could practically be useful to identify one of the vital controlling factors of gasification performance (i.e., ER impact on product gas flow characteristics) which might become a cost-effective solution in advance of commencement of any physical operation.
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Adam, Malik. "Multi-domain Vibrations Response of Externally Excited Fluid Conveyer Pipe in Industrial Steam Generator." Hyperscience International Journals 2, no. 1 (March 2022): 36–45. http://dx.doi.org/10.55672/hij2022pp36-45.
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Electric power is an indispensable consumer commodity for a little over a century now as all electric equipment in dwellings, commercial, and industry sectors are essentially dependent on electricity. Heat recovery steam generator, HRSG is an important system in combined cycle power plants. Indeed, excess vibrations induced on such devices may gradually lead to fatigue failure that affect the process of power output. This work investigates, models, and simulates the vibrations response of a fluid carrier pipe housed inside the cavity of the system while experiencing highly pressurized nearly perpendicular external force of extremely hot flue gas on the outside and pressurized water and water vapour from the inside. Transient and steady-state vibrations from initial conditions and the forcing function analysis are performed to account for the variation of damping, amplitude, and frequency responses of the system. Initial parameters used in the systems’ model are from industry subsequent to the OEM instructions. However, we introduce a new set of parameter values so as to observe the vibrational behaviour by varying these parameters. The purpose of performing a parameter-based vibration analysis is that parameter variation may point to different responses in the system. Indeed, this in turn indicates which set of parameters are suitable for rectifying the primary causes of undesired vibrations. To account for the consequence of mass flowrate, the model covers low pressure, intermediate pressure, and high-pressure constituents. The results obtained from the model are for the relationships of amplitude and phase angle as functions of frequency of the system. From these data, different interactions of quantities such as force, damping ratio, and number of dampers and vibration supports are observed. These results implores the implementation of new set of parameters to improve the agility of the system and minimize the impact of excess vibrations.
Dissertations / Theses on the topic "Steam-gas cavity"
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Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин." Thesis, Національний науковий центр "Харківський фізико-технічний інститут", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33188.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
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Вінніков, Денис Вікторович. "Електрофізичний вплив потужного підводного іскрового розряду на процеси обробки речовин." Thesis, НТУ "ХПІ", 2017. http://repository.kpi.kharkov.ua/handle/KhPI-Press/33183.
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Дисертація на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.09.13 – техніка сильних електричних та магнітних полів. – Національний технічний університет "Харківський політехнічний інститут", Харків, 2017.
Дисертація присвячена вдосконаленню електророзрядного обладнання, що використовується для обробки речовин сильно струмовим підводним іскровим розрядом. Проведено аналіз здобутих властивостей матеріалів та рідин в залежності від електричних параметрів розрядного кола, розмірів міжелектродного проміжку, конструкцій електрогідравлічних реакторів і тиску у реакторі. Запропоновані технологічні рекомендації щодо вдосконалення обладнання та процесів електрофізичного впливу на матеріали і рідкі середовища. В дисертації вдосконалено математичну модель щодо дослідження ранньої стадії розвитку іскрового каналу потужного іскрового розряду в парі води та у парогазовій оболонці. Вперше виявлено можливість швидкої (5–20 с) зміни окислювально-відновного потенціалу рідин в бік від'ємних значень з помірним підвищенням водневого показника. Проведено діагностику зміни фізико-хімічних властивостей води. Визначено склад та розміри частинок, що утворюються під час електричної ерозії електродів, запропоновано хімічну схему їх впливу на властивості води. Виявлено можливість подрібнення матеріалів, що моделюють відпрацьоване ядерне паливо, з метою вдосконалення методів його переробки. Оптимізовано параметри розрядного кола та реактора для подрібнення гумовотехнічних виробів у середовищі рідкого азоту. Доведено можливість обробки та зменшення розмірів зерен металів, що переплавляються в вакуумно-дугових пічках під впливом механіко-акустичних імпульсів, які утворюються високовольтними потужними підводними іскровими розрядами.Thesis for the scientific degree of the candidate of engineering sciences by specialty 05.09.13 – Technology of Strong Electric and Magnetic Fields. – National Science Center "Kharkiv Institute of Physics and Technology", Ministry of education and science of Ukraine National Technical University "Kharkiv Politechnic University" Kharkiv, 2017. This thesis is devoted to the improvement of the electric discharge equipment that is used for the substance treatment by heavy-current underwater spark discharges. The properties of materials and liquids were analyzed as a function of the electric parameters of discharge circuit, in particular, the charging voltage, the capacitance and the spark gap size. The structures of electrohydraulic reactors that are used for the treatment of general mechanical rubber goods and materials that simulate in the first approximation the spent solid nuclear fuel were developed and modernized to improve the methods of fuel recycling. The liquid degassing intensification method was suggested to initiate underwater spark discharges in the electrohydraulic reactor under the evacuation. The electrode system was created to provide the ordered motion of a pulsating steam and gas cavity in the water space at a reduced pressure in the reactor. A structure of the electric discharge generator of elastic vibrations that allows us to have an influence on the metal melts in vacuum-arc furnaces has been developed. It has been proved that mechanical acoustic vibrations generated by spark discharges in the liquid have a positive effect on the distribution of admixtures in treated metals and a decrease in the size of crystal grains. Technological recommendations on the improvement of the processes of electrophysical impact on the materials and liquid media were given. A mathematical model used for the investigation of the progress of current conducting channel that short-closes the spark gap at an early stage of its development, in particular a process of the expansion of current conducting channel and steam-gas cavity was improved. An opportunity for a fast (5–20 s) change in the redox potential of the liquid to the side of negative values with a moderate increase in the pH value was revealed for the first time. It has been shown that a change in the redox potential depends on the input of total energy into the treated volume. We established that a change in the redox potential is related to the processes that occur inside the steam-gas cavity, in particular chemical transformations that occur in its volume and the formation of electric erosion products of the electrodes that result in the chemical changes in the composition of treated medium. The size and dimensions of the particles that are formed during the electric erosion of electrodes have been defined. The chemical diagram of their influence on water properties has been suggested. A degree of the change in the redox potential is related to a number of formed polydisperse particles. Nanosize particles (37 % of the total volume of particles) with an increased physical and chemical activity were revealed.
Conference papers on the topic "Steam-gas cavity"
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Stasenko, David, Nikhil Rao, and Diganta Narzary. "Thrust Force Measurements in an Axial Steam Turbine Test Rig." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14673.
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Abstract Large mechanical drive steam turbines used in the oil & gas industry are operating at increasingly higher inlet pressure, generating higher shaft power. Those higher power requirements result in larger disk diameters and surface areas. High thrust forces can be a result, due to both the high inlet pressure and large disk surface area. Industry standards require oversizing of thrust bearings to handle uncertainty in thrust predictions. These factors make improvement in thrust prediction accuracy and mitigation strategies important. A full-size, axial flow steam turbine test rig capable of measuring turbine thrust, and static pressure in the upstream rotor-stator cavity was built and commissioned. The test rig was operated in single stage configuration for the tests reported here. The rotor disk had balance holes and stationary axial face seals near the disk rim. The face seals divide the upstream rotor-stator cavity into inner and outer circumferential cavities. The rotor-stator cavity upstream of the rotor disk was instrumented, on the stationary wall, to measure the radial and circumferential pressure distribution. Bearing thrust was measured with load cells. Tests varied nominal pressure ratios (1.2, 1.5, 2.0 and 3.0), velocity ratios (0.35–0.6), admission fractions (0.25–1.0) and shaft leakage flow rates. Circumferential pressure asymmetry, due to partial admission operation, was confined to the outer cavity. The inner cavity pressure coefficient was circumferentially uniform at all operating points. The average pressure coefficient in the upstream rotor-stator cavity generally decreased as the shaft leakage flow rate coefficient increased. Increased leakage flow rate coefficient also increased the magnitude of the upstream directed or negative thrust.
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San Andrés, Luis, Tingcheng Wu, Jose Barajas-Rivera, Jiaxin Zhang, and Rimpei Kawashita. "Leakage and Cavity Pressures in an Interlocking Labyrinth Gas Seal: Measurements vs. Predictions." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91507.
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Abstract Gas labyrinth seals (LS) restrict secondary flows (leakage) in turbomachinery and their impact on the efficiency and rotordynamic stability of high-pressure compressors and steam turbines can hardly be overstated. Amongst seal types, the interlocking labyrinth seal (ILS), having teeth on both the rotor and on the stator, is able to reduce leakage up to 30% compared to other LSs with either all teeth on the rotor or all teeth on the stator. This paper introduces a revamped facility to test gas seals for their rotordynamic performance and presents measurements of the leakage and cavity pressures in a five teeth ILS. The seal with overall length/diameter L/D = 0.3 and small tip clearance Cr/D = 0.00133 is supplied with air at T = 298 K and increasing inlet pressure Pin = 0.3 MPa ∼ 1.3 MPa, while the exit pressure/inlet pressure ratio PR = Pout/Pin is set to range from 0.3 to 0.8. The rotor speed varies from null to 10 krpm (79 m/s max. surface speed). During the tests, instrumentation records the seal mass flow (ṁ) and static pressure in each cavity. In parallel, a bulk-flow model (BFM) and a computational fluid dynamics (CFD) analysis predict the flow field and deliver the same performance characteristics, namely leakage and cavity pressures. Both measurements and predictions agree closely (within 5%) and demonstrate the seal mass flow rate is independent of rotor speed. A modified flow factor Φ¯=m.T/PinD1-PR2 characterizes best the seal mass flow with a unique magnitude for all pressure conditions, Pin and PR.
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Bohn, Dieter, Jing Ren, and Christian Tuemmers. "Investigation of the Unstable Flow Structure in a Rotating Cavity." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90494.
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Annular cavities are found inside rotor shafts of turbomachines with an axial or radial throughflow of cooling air, which influences the thermal efficiency and system reliability of the gas turbines. The flow and heat transfer phenomena in those cavities should be investigated in order to minimize the thermal load and guarantee system reliability. An experimental rig is set up in the Institute of Steam and Gas Turbines to analyze the flow structure inside the rotating cavity with an axial throughflow of cooling air. The corresponding 3D numerical investigation is carried out with the in-house fluid solver CHTflow, in which the Coriolis force and the buoyancy force are implemented in the time-dependent Navier-Stokes equations. Both the experimental and numerical results show the whole flow structure rotating against the cavity rotating direction. The flow passing the observation windows shows the quite similar trajectories in the experimental and numerical results. The computed sequences and periods of the vortex flow structure correspond closely with those observed in the experiment. Furthermore, the numerical analysis reveals a flow pattern changing between single pair, double pairs and triple pairs vortices. It is suggested that the vortices inside the cavity are created by the gravitational buoyancy force in the investigated case, and the number and strength of the vortices are controlled mainly by the Coriolis force.
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Ma, Can, Zhiqiang Qiu, Jinlan Gou, Jun Wu, Zhenxing Zhao, and Wei Wang. "Axial Force Balance of Supercritical CO2 Radial Inflow Turbine Impeller Through Backface Cavity Design." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-76019.
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The supercritical CO2-based power cycle is very promising for its potentially higher efficiency and compactness compared to steam-based power cycle. Turbine is the critical component in the supercritical CO2-based cycle which delivers the power. Compared to the gas turbine or steam turbine of similar power output, the size of the supercritical CO2 radial turbine is much smaller and the axial force on the impeller is much larger. The load on the thrust bearing could be too heavy for long-term safe operation. Therefore, it is necessary to balance the axial force on the impeller through aerodynamic design to reduce the load on the thrust bearing. The impeller backface design with radial pump-out vanes proves to be an effective design to reduce the axial force on the impeller of radial turbomachinery, which is widely used in the pump industry. This work investigates the impeller backface cavity flow of a supercritical CO2 radial turbine and the application of the pump-out vanes to the impeller through computational fluid dynamics simulations. Design variations of the pump-out vane are presented and their performance variations are discussed from the view of viscous compressible fluid, instead of the commonly assumed inviscid incompressible fluid in the pump industry.
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Rubechini, Filippo, Michele Marconcini, Andrea Arnone, Stefano Cecchi, and Federico Dacca`. "Some Aspects of CFD Modeling in the Analysis of a Low-Pressure Steam Turbine." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27235.
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A three-dimensional, multistage, Navier-Stokes solver is applied to the numerical investigation of a four stage low-pressure steam turbine. The thermodynamic behavior of the wet steam is reproduced by adopting a real-gas model, based on the use of gas property tables. Geometrical features and flow-path details consistent with the actual turbine geometry, such as cavity purge flows, shroud leakage flows and partspan snubbers, are accounted for, and their impact on the turbine performance is discussed. These details are included in the analysis using simple models, which prevent a considerable growth of the computational cost and make the overall procedure attractive as a design tool for industrial purposes. Shroud leakage flows are modeled by means of suitable endwall boundary conditions, based on coupled sources and sinks, while body forces are applied to simulate the presence of the damping wires on the blades. In this work a detailed description of these models is provided, and the results of computations are compared with experimental measurements.
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Kim, Hwan Yeol, Kwang Soon Ha, Jong Hwan Kim, Seong Wan Hong, and Jin Ho Song. "A Core Catcher Concept and First Experimental Results." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30038.
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In a postulated core melt accident, if a molten core is released outside a reactor vessel despite taking mitigation actions, the core debris would relocate in the reactor cavity region and attack the concrete wall and basemat of the reactor cavity. This will potentially result in inevitable concrete decompositions and possible radiological releases. To prevent direct contact of the melt and basemat concrete of the cavity, a core catcher concept is suggested, which can passively arrest and stabilize the molten core material inside the reactor cavity. The core catcher system includes a retention device for the molten core material, a cooling water storage tank, and a compressed gas tank. Upon ablation of the sacrificial layer on top of the retention device while molten core material is discharged, a mixture of water and gas is injected from below. It is expected that a simultaneous injection of water and gas could prevent a possible steam explosion/spike. It could also suppress the rapid release of steam which might result in fast over-pressurization of the containment. A test facility for the core catcher using a thermite reaction technique for the generation of the melt was designed and constructed at KAERI. The first series of tests were performed by using a mixture of Al, Fe2O3, and CaO as a stimulant. As a first try, only water was injected from the bottom of the melt through five water injection nozzles when the melt front reached the water injection nozzles. In this paper, the core catcher concept and the related provisions are suggested. A description of the test facility for the core catcher, the thermite composition, and the methods of experiment is included. The first experimental results with only water injected from the bottom of the melt are discussed.
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Tanaka, Ryozo, Takao Sugimoto, Masanori Ryu, Masayoshi Kinugawa, and Koichiro Tsuji. "Continuing Improvements of 20MW-Class GT Kawasaki L20A." In ASME Turbo Expo 2006: Power for Land, Sea, and Air. ASMEDC, 2006. http://dx.doi.org/10.1115/gt2006-90394.
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Kawasaki Heavy Industries launched the first model of L20A gas turbine, rated at 18MW, in 2001 [1]. After the first model was launched, continuing improvements in both performance and durability have been made [2]. This paper describes the latest improvement activities, including cooling improvement of the 1st stage turbine blades using the results from an optical pyrometer thermal mapping system (Rotamap II) and performance improvements achieved by reducing the secondary air flow. In addition, by applying the non-cooled 2nd stage turbine blades made of single crystal material, plus improved rim sealing structure, cavity temperature was kept below the desired limit with a reduced amount of cooling air being required. KHI also developed a L20A “STEAM INJECTION” version. This system enables the utilization of the variable surplus steam of a cogeneration plant to increase the electric output. This paper describes the test result of L20A model gas turbine with steam injection capabilities. In the test, performance and emissions were measured as usual, but in addition, metal temperature of 1st stage blade was measured using the pyrometer system in order to confirm the propriety of the TIT de-rate schedule which keeps the metal temperature at the same level as the L20A “NORMAL” version under the steam injected condition.
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Fakhari, Keramat, Thomas Hofbauer, and Anton Weber. "Numerical Investigation of Unsteady Blade Row Interactions With Leakage Flow in Steam Turbines." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59613.
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This paper focuses on the interaction of labyrinth seal leakage flows within two stages of a HP and an IP steam turbine. Numerical studies have been carried out with the DLR in-house code TRACE [1] to show the impact of the labyrinth seal leakage flow on the total loss generation in both steady and time accurate simulations. CFD results are verified by the in-house 2D through-flow method of Siemens Energy. The investigations are divided into five steps: 1. Real gas effects, 2. Steady simulations of the core flow alone and its interaction with the cavity flow to provide insights about loss production contributed by the mixing process of the re-entering leakage flow into the main flow, 3. Understanding and modeling of unsteady phenomena within such interacting flows, 4. Effects of reduction of the axial distance between the two stages on the mixing process in time accurate simulations. 5. Comparison of blade loads calculated by Siemens’ CAE tools and predicted by TRACE.
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Oshkai, Peter, and Oleksandr Barannyk. "Quantitative Visualization of Unstable, Acoustically Coupled Shear Layers in Deep Axisymmetric Cavities." In ASME 2014 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/pvp2014-28271.
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High-amplitude acoustic pressure fluctuations associated with locked-on, resonant flow states frequently occur in engineering systems that involve internal cavities located in pipelines, such as components of gas transport systems, steam delivery pipelines and jet engines. This paper describes the evolution of fully turbulent, acoustically coupled shear layers that form across deep, axisymmetric cavities. Effects of geometric modifications of the cavity edges on the separated flow structure were investigated using digital particle image velocimetry (PIV). The internal flow was non-intrusively accessed by means of a borescope, which allowed illumination and optical recording of flow tracers inside the cavity. Instantaneous, phase- and time-averaged patterns of velocity and vorticity provided insight into the flow physics during flow tone generation and noise suppression by the geometric modifications. In particular, the first mode of the shear layer oscillations was significantly affected by shallow chamfers located at the upstream and, to a lesser degree, the downstream edges of the cavity. Specifically, the introduction of the chamfers affected the phase and the location of formation of large-scale vortical structures in the shear layer, which is associated with a maximum of the vorticity thickness across the cavity opening. In turn, these changes in the flow structure affected the amplitude of acoustic pressure pulsations.
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Feng, Jinyong, Enrique Velez Lopez, William Robb Stewart, Ralph Wiser, Emilio Baglietto, and Koroush Shirvan. "Heat Transfer Analysis of a Conceptual Horizontally-Oriented High Temperature Gas-Cooled Reactor." In 2021 28th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/icone28-65828.
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Abstract High temperature gas-cooled reactors (HTGRs) have been constructed around the world since the 1960s. Compared to light water reactors, HTGRs feature a low core power density, which ultimately results in the need for larger components and structures. The successful widespread deployment of HTGRs will likely require a significant reduction in reactor building size per kW, to compete with other sources of carbon-free energy. The Modular Integrated Gas-cooled High Temperature Reactor (MIGHT-R) has been recently proposed to leverage inherent safety characteristics of HTGRs and its proven technology, while increasing its reactor building power density by 4 to 5 times. Contrarily to the vertical side-by-side orientation of the reactor core and steam generator of the typical HTGR design, the MIGHTR primary system components are laid horizontally, inline with one another. In this paper, a design embodiment of MIGHT-R concept is presented and preliminary heat transfer analysis under normal operating conditions is performed adopting a simplified porous representation of the flow behavior inside the reactor core and steam generator. The predicted mass flow rates in the fuel region, inner reflectors and outer reflectors agree with analytical estimations. A set of sensitivity tests for components variations are presented to provide insights on the influence of design parameters. A preliminary design reactor cavity cooling system (RCCS) is presented which is basically a 100 °C “water shell” surrounding the reactor vessel and it only covers the reactor core regions. Comparison of the same design with different orientations is also made and indicates that the mass flow and temperature distribution inside the reactor core have low dependence on orientation. Based on the computational results, the stratification of the coolant in the horizontal configuration for normal operation is deemed negligible. The presented work supports the normal operation feasibility of a horizontally-oriented HTGR concept with its potential to significantly reduce HTGR capital cost.