Academic literature on the topic 'Representative upstream conditions'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Representative upstream conditions.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Representative upstream conditions"
1
Cao, Ping, Xiangpeng Mu, Xiang Li, Baoligao Baiyin, Xiuying Wang, and Wanyue Zhen. "Relationship between Upstream Swimming Behaviors of Juvenile Grass Carp and Characteristic Hydraulic Conditions of a Vertical Slot Fishway." Water 13, no. 9 (May 6, 2021): 1299. http://dx.doi.org/10.3390/w13091299.
Full textAbstract:
The successful fish upstream movement through a dam/gate is closely associated with the hydraulic conditions of a fishway. To improve the passage efficiency, this study investigated the upstream swimming behaviors of juvenile grass carp, a representative fish of four major Chinese carps, under characteristic hydraulic conditions of a designed vertical slot fishway model. The impacts of different discharges and baffle lead angles on the successful movement of test fish were analyzed, and the selection of the movement trajectory was studied through overlay of their upstream swimming trajectories on the water flow field resulting from numerical modeling. We found that under the same discharge, the percentage of successful test fish movement with a lead angle of 45° was higher than 60° and 30°. Within a fixed lead angle, the higher the discharge, the lower the percentage of successful movement. During upstream movement, the test fish had a preferred water velocity of 0.01–0.45 m/s in the pool, and avoided areas where the turbulence kinetic energy (TKE) was greater than 0.012 m2/s2. These results provide a basis for the hydraulic design of vertical slot fishways and a reference for studying swimming behaviors of other fish species.
2
Guardiola, Carlos, Benjamin Pla, Pau Bares, and Javier Mora. "An on-board method to estimate the light-off temperature of diesel oxidation catalysts." International Journal of Engine Research 21, no. 8 (December 16, 2018): 1480–92. http://dx.doi.org/10.1177/1468087418817965.
Full textAbstract:
Current diesel engine regulations include on-board diagnostic requirements so that after-treatment systems need on-board methods to detect their aging state through the available measurements. In a state-of-the-art diesel exhaust line, two temperature and [Formula: see text] measurements can be found upstream and downstream of the diesel oxidation catalyst. Thus, the strategy presented in this article makes use of these measurements to estimate the light-off temperature, which has been widely studied as a characteristic of diesel oxidation catalyst aging. The light-off temperature estimation potential is evaluated first under dynamic engine operating conditions, in which [Formula: see text] measurements are proved to be precise enough to detect oxidation. However, dynamic conditions make the association of a representative temperature with an oxidation event difficult. Therefore, the method makes use of more controlled conditions at idle, during which the exhaust temperature decreases avoiding dynamics of normal driving conditions. During the idle, post-injection pulses are applied to determine whether oxidation occurs at a representative temperature measured by the upstream temperature sensor. The result of each pulse is used to generate a database. Then, after a long enough time window, the database generated will allow characterizing non-oxidation and oxidation temperatures, with an intermediate interval of indefinition. This article shows how the temperatures of these ranges increase as the light-off temperature increases, thereby validating the proposed method for light-off temperature estimation.
3
Chen, Yongping, Ninglin Jiang, and Changkuan Zhang. "RIVERBED EVOLUTION OF YANGTZE ESTUARY AND ITS RESPONSE TO THE HYDRODYNAMIC CHANGES AT UPSTREAM." Coastal Engineering Proceedings 1, no. 33 (December 13, 2012): 92. http://dx.doi.org/10.9753/icce.v33.sediment.92.
Full textAbstract:
The riverbed evolution of upper part of Yangtze estuary, Chengtong reach, is analyzed by comparison of 6 sets of bathymetry data during 1977~2011. The significant changes of water depth profiles along 6 representative cross-sections indicate the reach is still in the process of development. In order to get a better understanding of the effect of river discharge at upstream on the riverbed evolution of Chengtong reach, a series of numerical experiments are implemented by specifying different river discharge conditions at the upper boundary. The corresponding discharge ratio at main sub-reaches is compared to reveal the response of the riverbed evolution to the hydrodynamic changes at upstream. The results show that with the increase of river discharge, the discharge ratio in the main channels of Fujiangsha sub-reach and Rugaosha sub-reach increases, but it changes to decrease when the upstream river discharge becomes very large; however, the discharge ratio in the main channel of Tongzhousha sub-reach always decreases with the increase of river discharge at upstream.
4
Bailey, D. W., K. M. Britchford, J. F. Carrote, and S. J. Stevens. "Performance Assessment of an Annular S-Shaped Duct." Journal of Turbomachinery 119, no. 1 (January 1, 1997): 149–56. http://dx.doi.org/10.1115/1.2841003.
Full textAbstract:
An experimental investigation has been carried out to determine the aerodynamic performance of an annular S-Shaped duct representative of that used to connect the compressor spools of aircraft gas turbine engines. For inlet conditions in which boundary layers are developed along an upstream entry length, the static pressure, shear stress and velocity distributions are presented. The data show that as a result of flow curvature, significant streamwise pressure gradients exist within the duct, with this curvature also affecting the generation and suppression of turbulence. The stagnation pressure loss within the duct is also assessed and is consistent with the measured distributions of shear stress. More engine representative conditions are provided by locating a single-stage compressor at inlet to the duct. Relative to the naturally developed inlet conditions, the flow within the duct is less likely to separate, but mixing out of the compressor blade wakes increases the measured duct loss. With both types of inlet conditions, the effect of a radial strut, such as that used for carrying loads and engine services, is also described both in terms of the static pressure distribution along the strut and its contribution to overall loss.
5
DERZHO, OLEG, and ROGER GRIMSHAW. "Solitary waves with recirculation zones in axisymmetric rotating flows." Journal of Fluid Mechanics 464 (August 10, 2002): 217–50. http://dx.doi.org/10.1017/s0022112002008790.
Full textAbstract:
In this paper, we describe a theoretical asymptotic model for large-amplitude travelling solitary waves in an axially symmetric rotating flow of an inviscid incompressible fluid confined in an infinitely long circular tube. By considering the special, but important, case when the upstream flow is close to that of uniform axial flow and uniform rotation, we are able to construct analytical solutions which describe solitary waves with ‘bubbles’, that is, recirculation zones with reversed flow, located on the axis of the tube. Such waves have amplitudes which slightly exceed the critical amplitude, where there is incipient flow reversal. The effect of the recirculation zone is to introduce into the governing amplitude equation an extra nonlinear term, which is proportional to the square of the difference between the wave amplitude and the critical amplitude. We consider in detail a special, but representative, class of upstream inflow conditions. We find that although the structure of the recirculation zone is universal, the presence of such solitary waves is quite sensitive to the actual upstream axial and rotational velocity shear configurations. Our results are compared with previous theories and observations, and related to the well-known phenomenon of vortex breakdown.
6
Nazrul-Islam, A. K. M., Fahmida Khan, Ambia Khatun, M. R. Khan, A. N. M. Abdullah, and P. K. Jha. "ECOLOGICAL CONDITIONS OF A TEMPORARY WETLAND IN BANGLADESH." Ecoprint: An International Journal of Ecology 18 (December 21, 2013): 71–76. http://dx.doi.org/10.3126/eco.v18i0.9413.
Full textAbstract:
Investigation has been done to gain evidence on certain chemical properties of water and vegetation in area representative of the various wetland habitats which go under water during rainy season. The measurements were done with edaphic condition, water chemistry, and floristic composition. Water was neutral to alkaline and pH varied from 6.97 to 7.20 and conductivity was in the range of 97.5 m mhos to 240 m mhos. Seasonal variation of chloride content was observed throughout the year and the highest chloride (104.96 mg/l) was in the month of October. Dissolved oxygen concentration was very low (2.99 mg/l) in the month of October. With the decrease of water, the value of alkalinity became double (76.0 mg/). No distinct variation in the content of hardness was observed in the three different locations. Temporary hardness varied from 0.1 0 to 0.56 mg/l. High value of total solids in the month of July (70 mg/l) indicated that high amount of sediment are coming with the flow of water from upstream. Total suspended solids were higher than dissolved solids. Exchangeable cations were low in the beginning and an increasing tendency of Na and Ca was observed in the later stages of marsh formation. DOI: http://dx.doi.org/10.3126/eco.v18i0.9413Ecoprint: An International Journal of EcologyVol. 18, 2011 Page: 71-76 Uploaded date: 12/22/2013
7
Tang, Nanbo, Xiaogang Wang, Yun Li, Long Zhu, Zhushuan Tang, Hongze Li, Feifei He, Yongzeng Huang, and Zhengxian Zhang. "Laboratory Studies on the Rheotaxis of Fish under Different Attraction Flow Conditions." International Journal of Environmental Research and Public Health 19, no. 9 (May 9, 2022): 5744. http://dx.doi.org/10.3390/ijerph19095744.
Full textAbstract:
The damming of the river changes the structure of the original river ecosystem, and although fish passage plays an important role in maintaining the connectivity of the river ecosystem, the fish have difficulty finding the fish passage entrance during the upstream process. This paper studied the rheotaxis of fish under three different water flow conditions experimentally through recirculating water tanks. To better understand the response of Crucian carp (Carassius auratus) to water flow stimulation, the representative swimming trajectory, sensing success rate, attraction success rate, reaction time, and attraction time of the fish were analyzed by using a video monitoring system. The experimental results showed that fish responded differently to single-peak and lateral bimodal outflow conditions: (1) the single-peak outflow condition had a much better attraction effect than the lateral bimodal outflow condition, both in terms of sensing success rate and attraction success rate; (2) the fish swam mainly in the middle area of the lateral bimodal outflow condition, while the fish swam more evenly in the single-peak outflow condition. Therefore, setting the attraction current at the right time and near the entrance of the fish passage may help to improve the effect of fish attraction.
8
Sun, Zhilin, Haolei Zheng, and Lixia Sun. "Analysis on the Characteristics of Bed Materials in the Jinghong Reservoir on the Lancang River." Sustainability 13, no. 12 (June 17, 2021): 6874. http://dx.doi.org/10.3390/su13126874.
Full textAbstract:
Nine samples of bed materials along the Jinghong reservoir on the Lancang River were obtained using a gravity sampler. The grain size characteristics of the samples were analyzed by the laser diffraction particle size analyzer. The results show that the median grain size of bed materials is in the range of 6.7 to 18.9 µm. From the upstream to the front of the dam, the overall grain size of the bed materials tends to decrease significantly; the sorting is poor but becomes better along the way; the skewness gradually changes from negative to near symmetrical; the kurtosis is platykurtic and mesokurtic with little change along the way. Based on the measured data, an exponential model is constructed to describe the distribution of representative grain size of bed materials along the way. Furthermore, the concept of representative particle Reynolds number is proposed. The relationship between representative particle Reynolds number and flow parameters with boundary conditions is established, and the coefficient and exponents in the equation are determined based on the measured data of the Jinghong reservoir. This study provides valuable first-hand information for reservoir sediment research and new ideas for sediment sorting and deposition studies.
9
Kinney, Patrick, Gwi-Nam Bae, David Pui, and Benjamin Liu. "Particle Behavior in Vacuum Systems: Implications for In-Situ Particle Monitoring in Semiconductor Processing Equipment." Journal of the IEST 39, no. 6 (November 1, 1996): 40–48. http://dx.doi.org/10.17764/jiet.2.39.6.p7414773u18n5t20.
Full textAbstract:
The flow of aerosol in vacuum conditions representative of many semiconductor processes (100 sccm, 1 Torr). was investigated. The study was performed using aerosols with highly nonuniform spatial distributions. An ideally nonuniform aerosol was produced by generating an aerosol beam using an aerodynamic lens. The flow containing the aerosol beam was drawn through vacuum system components. The size of the beam was measured upstream and downstream of these components by collecting the aerosol on a filter and observing the deposition pattern. Very little mixing phenomenon was observed. These results point to a potential limitation in the methods employed by the semiconductor industry for in-situ particle monitoring in vacuum systems. A simple solution to this flaw is suggested.
10
Jasek, Martin, and Amy Pryse-Phillips. "Influence of the proposed Site C hydroelectric project on the ice regime of the Peace River." Canadian Journal of Civil Engineering 42, no. 9 (September 2015): 645–55. http://dx.doi.org/10.1139/cjce-2014-0425.
Full textAbstract:
The objectives of the study were to describe the existing ice conditions in the Peace River and to predict changes as a result of the proposed Site C Clean Energy Project (the Project). The analyses of changes due to the Project were conducted using the CRISSP and PRTIGM models. Sixteen winters were simulated to provide a representative range of meteorological conditions on which to base the conclusions of the study. Potential changes are described in terms of the following ice characteristics: maximum upstream extent of ice cover; timing of ice cover formation and break-up; freeze-up and break-up water levels at the Town of Peace River; ice thickness; changes in ice conditions relevant for river ice crossings. The analyses also included predicting changes in these ice characteristics due to the combined influence of the Project and the proposed Dunvegan Hydro Project in Alberta. Two future climate scenarios were also considered.
Book chapters on the topic "Representative upstream conditions"
1
Graf, William L. "Sediment and Plutonium Storage Upstream from Cochiti." In Plutonium and the Rio Grande. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195089332.003.0014.
Full textAbstract:
The foregoing chapters demonstrated that large amounts of sediment and much of the plutonium entering the Northern Rio Grande have been stored along the river channel. A composite budget analysis gives the quantities of materials involved annually, but except in very broad terms it does not describe where the materials are stored. It is a matter of scale: The budget indicates the overall quantities of sediment and plutonium stored in the system but does not reveal on a local scale where one might search for the materials. The next chapters show that the storage process has particular geographic characteristics and that in representative reaches it is possible to map those sediments that were deposited during the years of maximum input of plutonium into the system. These critical deposits are likely to contain more plutonium than are similar deposits of other years. In this way, the evidence of environmental change along the river provides a guide for determining the fate of plutonium in the system. A sampling program for assessing the storage of plutonium along the Northern Rio Grande depends on the development of the connections among vegetation communities, fluvial landforms, sedimentary deposits, and plutonium contents. Although it is not possible here to map and interpret completely the entire 313 km of river from Espanola to San Marcial, limited reaches can serve as representatives of larger portions of the whole. Eleven representative reaches, each about 3 to 6 km long, provide information on the entire study area because each representative reach exemplifies the conditions that obtain over a much larger portion of the total length of the river. My selection of the representative reaches began by reviewing the entire river by aerial photography and then directly in the field. The river divides itself into sections based on the geomorphologic conditions as modified by engineering works. Each representative reach illustrates the conditions within one larger section. For example, the Frijoles representative reach is similar to other relatively short reaches throughout White Rock Canyon.
2
Graf, William L. "Sediment and Plutonium Storage Downstream from Cochiti." In Plutonium and the Rio Grande. Oxford University Press, 1995. http://dx.doi.org/10.1093/oso/9780195089332.003.0015.
Full textAbstract:
Downstream from White Rock Canyon and the reaches discussed in Chapter 9, the Rio Grande takes on a different character because of the presence of Cochiti Dam at the lower end of the canyon. From that point downstream, the river’s present appearance and behavior reflect the influence of the dam, which was closed in 1973. Although the channel has become narrower throughout the length of the Rio Grande since the 1930s, this change is most pronounced south of Cochiti Dam. Downstream from the Los Lunas representative reach (which ends near Bernardo), the character of the Rio Grande changes radically. Immediately below Bernardo, the Rio Puerco joins the main river, bringing with it a huge load of sediment. The Rio Grande Valley becomes much wider below Bernardo, and the twentieth-century narrowing of the channel, aided by engineering works, is even more pronounced than in upstream areas, and the vegetation community is dominated by tamarisk. The final three representative reaches discussed in this chapter share the features of great valley width, extensive channel changes, and widespread impacts of engineering works. The Peña Blanca reach, a 5-km channel section, represents conditions common along 40 km of the Northern Rio Grande between Cochiti Pueblo (site of Cochiti Dam) and the confluence with the Jemez River. The river passes Peña Blanca, a settlement based on irrigated agriculture dating from the early nineteenth century. The reach is typical of the conditions in a portion of the river where the flood plain is several times the width of the channel and where the channel has been exceedingly unstable. The reach is also instructive concerning the results of levee construction (in 1953) and dam closure (in 1973). The behavior of the channel in the Pena Blanca reach between the early 1940s and about 1990 has consistently included locational instability and progressive adjustment from a broad-braided configuration to a narrow, straighter alignment. In the 1940s, the channel was wide and unstable, with numerous major and minor threads, but the gradual reduction in water yield and radical reduction in the annual flood peaks resulted in the progressive isolation and closure of secondary channels.
Conference papers on the topic "Representative upstream conditions"
1
Allan, William, Roger Ainsworth, and Steven Thorpe. "Unsteady Heat Transfer Measurements From Transonic Turbine Blades at Engine Representative Conditions in a Transient Facility." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-53835.
Full textAbstract:
The unsteady heat transfer measurements about a transonic turbine blade at engine representative Mach and Reynolds numbers are presented. High density, fast response thin film gauges are employed at the mid-height streamline. A description of the novel development of gold gauges together with a brief overview of their calibration and signal processing is presented. Detailed time and phase-averaged measurements have been obtained, providing insight into the role of upstream nozzle guide vane wakes and shock features. These heat transfer results compliment recent fast-response aerodynamic results on this and similar transonic profiles, which highlight the dominance of the upstream vane-rotor interaction over convected wake segments, particularly in light of unsteady turbine blade loading. From a heat transfer standpoint however, whilst the periodic shock events contributed to abrupt, localized heat transfer enhancements, the influence of NGV wake segments on the boundary layer could not be discounted when duration of unsteadiness was considered.
2
Williams, M. A., J. F. Carrotte, A. J. Moran, and A. D. Walker. "Impact of Upstream Boundary Conditions on Fuel Injector Performance in a Low TRL Reacting Flow Experimental Facility." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75621.
Full textAbstract:
It has been known for a sometime that the compressor exit profile can have a significant effect on the overall performance of the fuel injector. This effect has been increased recently with the advent of larger leaner injection systems. With a modern gas turbine combustion system the fuel injectors are presented with a non-uniform feed generated by the upstream compressor and OGV/pre-diffuser assembly. For generic lean burn combustion systems previous experimental and numerical work highlighted a complex interaction between the compressor efflux and the upstream diffuser. Circumferential non-uniformities in the flow presented to the fuel injector can amount up to ±10% of the mean velocity. Previous investigations examined only the isothermal flow field and the effects of this level of non-uniformity on reacting performance are not known. There are potential impacts on local fuel atomisation, air/fuel mixing and hence emissions performance. The main aim of this paper is to observe and assess the effect of these upstream conditions using a reacting flow test facility. In the initial design phases reacting flow experiments are generally conducted in simple, single sector plenum fed test facilities. Since this does not capture the effects of non-uniformities modifications were made to the facility to produce an aerodynamically representative feed. CFD was used in the design process to ensure that the aerodynamic features present in engine geometries would be faithfully reproduced by the test rig modifications. The CFD also highlighted changes in the downstream isothermal flow field. This included differences in the overall effective area of the fuel injector and, importantly, a redistribution of mass flow between the various fuel injector passages. Additionally, the cone angle, and the flow structure downstream was observed to change. Back-to-back tests were then conducted in a reacting flow test facility for various pilot-mains fuel flow splits and air-to-fuel ratios. Visualisation of the flame showed notable qualitative differences in the structure and stability of the flame. Quantitative measurements indicated that, compared to a plenum feed, a representative feed produced changes in the production of carbon monoxide, unburned hydrocarbons and oxides of nitrogen. Emission results were used to calculate the extent of the mass flow redistribution between passages. From this a correction was applied to the estimated AFRs. This correction did not fully collapse the emissions data, suggesting that while the mass flow redistribution contributes to the change in emissions it is not fully responsible. Covered in this paper are initial observations. However, further work is required to fully understand how the changes to the aerodynamic flow field alter the emissions performance, but it is clear that having a representative fuel injector feed is important in low TRL testing.
3
Karakasis, Marios K., Edward M. J. Naylor, Robert J. Miller, and Howard P. Hodson. "The Effect of an Upstream Compressor on a Non-Axisymmetric S-Duct." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-23404.
Full textAbstract:
This paper considers the effect of an upstream compressor stage on a compressor inter-spool duct. The duct geometry must be fixed early in the engine design process, well before the design of the upstream stages. It is therefore important that the designer has a good physical insight into how engine representative inlet conditions affect the limits of the duct design space. An experimental and computational investigation of two strutted inter-spool S-ducts was undertaken. Both were tested with and without an upstream stage present. The first duct is of a conventional axisymmetric design with a radius change to length ratio ΔR/L = 0.50. This duct is characteristic of the most extreme ducts considered in modern engine design. The second duct is of a non-axisymmetric design and is 20% shorter, ΔR/L = 0.625. This is well beyond the design limit of axi-symmetric strutted ducts. The paper shows that the presence of the upstream stage increases the duct loss by 54%. The rise in loss occurs on the hub wall and is the result of the incoming stator wakes pooling onto the hub wall, forming a row of contra-rotating streamwise vortex pairs adjacent to the hub wall. These vortices pump boundary layer fluid into the free stream, thus raising the mixing loss. In the non-axisymmetric duct an extra mechanism was observed. The streamwise vortex pairs act to ‘re-energise’ the boundary layer. This reduces strut secondary losses caused by the endwall contouring. The net result is that on the non-axisymmetric duct the presence of an upstream stage only increases the duct loss by 28%. Comparing the two ducts, it is shown that with engine representative inlet conditions, the conventional symmetric duct and 20% shorter non-axisymmetric duct have identical performance. This shows that low loss ducts can be designed which are significantly more extreme than current design limits.
4
Margarone, Michele, Stefano Magi, Giuseppe Gorla, Stefano Biffi, Paolo Siboni, Gianluca Valenti, Matteo C. Romano, Antonio Giuffrida, Emanuele Negri, and Ennio Macchi. "Revamping, Energy Efficiency and Exergy Analysis of an Existing Upstream Gas Treatment Facility." In ASME 2010 4th International Conference on Energy Sustainability. ASMEDC, 2010. http://dx.doi.org/10.1115/es2010-90213.
Full textAbstract:
Surface oil and gas treatment facilities in service for decades are likely to be oversized due to the natural depletion of their reservoirs. Despite these plants might have been designed modularly, meaning they comprise multiple identical units serving the same task, such units operate often in conditions far from the design point and inefficiently. This work analyzes the revamping options of an existing upstream gas facility, which is chosen because representative of a wide set of plants. A flexible numerical model, implemented in the HYSYS environment and dynamically linked to an Excel spreadsheet, includes the performance maps of all turbo machineries and the main characteristics of the investigated modifications in order to run simulation for many gas input conditions and to predict the performance over a year of operation and for different possible future scenarios. The first objective is to assess economically the considered options, which shall be applied only if yielding short return times of the investment since the reservoir is mature. Moreover, all options are appreciated adopting a figure of merit, here defined, that compares the overall energy consumption to that calculated with state-of-the-art technologies. In addition, an exergy and an environmental analyses are executed.
5
Notaristefano, Andrea, and Paolo Gaetani. "The Role of Turbine Operating Conditions on Combustor-Turbine Interaction – Part 1: Change in Expansion Ratio." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-81707.
Full textAbstract:
Abstract Aeroengine lean-burn combustors release vorticity and temperature perturbations that, interacting with the first turbine stage, impact the stage aerodynamics, the blade cooling and noise production. The first of these issues is addressed in this paper that is part 1 of a two-fold contribution. A detailed experimental analysis is carried out to study the impact on the combustor-turbine interaction of the off-design conditions experienced by aero-engines in their duty. Engine-representative disturbances are generated by a combustor simulator able to produce swirling entropy waves. Two injection positions and four injection cases are studied. Experimental measurements are carried out at three traverses: upstream of the stator, at the interstage, and downstream of the rotor. This paper analyses the effect of the stage expansion ratio: two values are studied, namely 1.4 and 1.76, representative of subsonic and transonic flow conditions. They are chosen imposing similar velocity triangles at the rotor inlet. Results show that the swirl profile considerably impacts the stage aerodynamics. The aerothermal flow field downstream of the stator is modified significantly by the combustor disturbances. Conversely, downstream of the rotor, the differences in aerodynamics lessen. However, the entropy wave persists at the stage outlet and its transport depends on both the operating point and the injection position.
6
Barringer, M. D., K. A. Thole, D. L. Breneman, K. M. Tham, and V. Laurello. "Effects of Centrifugal Forces on Particle Deposition for a Representative Seal Pin Between Two Blades." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-68777.
Full textAbstract:
Many land-based gas turbine applications are conducive to the formation of rust in the supply piping and other components that are upstream of the gas turbine. Many of these applications do not incorporate an effective filtration system for removing rust particles from the secondary air systems thereby resulting in rust deposits. Deposits in the small passages significantly block the secondary flow that ultimately reduces component life. This study investigates the effects of rust deposition in a geometry representative of an axial seal pin between two blades. Initial studies were performed to determine the effects of engine-representative particle composition, temperature, and centrifugal acceleration on deposition characteristics. These initial results pointed to the importance of simulating centrifugal forces representative of that experienced in the engine. A new facility was developed to directly measure flow blockages under static conditions and under rotational conditions.
7
Marconcini, Michele, Roberto Pacciani, Andrea Arnone, and Francesco Bertini. "Low-Pressure Turbine Cascade Performance Calculations With Incidence Variation and Periodic Unsteady Inflow Conditions." In ASME Turbo Expo 2015: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/gt2015-42276.
Full textAbstract:
The performance of a Low-Pressure Turbine (LPT) cascade were investigated under both steady and periodic unsteady inflow boundary conditions with different Reynolds numbers and a reduced frequency representative of real LPT working conditions. A sensitivity analysis to the variation of the inlet flow angle was performed to assess the performance during off-design operation. The numerical framework is based on a steady/unsteady Reynolds Averaged Navier-Stokes (RANS/URANS) flow solver which includes some state-of-the-art transition-sensitive turbulence closures. Boundary conditions for the time-accurate computations upstream of the cascade were derived from the experimental characterization of a moving bar system used to generate the wake periodic perturbations. The computed performance of the cascade, as a function of Reynolds number and incidence angle variation, is discussed in comparison with experimental data. Steady and unsteady boundary layer quantities are also compared with measurements in order to gain more insights into the loss generation process and to better support the numerical results. Such an assessment proves that the proposed procedure is adequate for the analysis of the off-design behavior of cascades operating in low pressure turbine conditions.
8
Satta, Francesca, Daniele Simoni, Marina Ubaldi, Pietro Zunino, and Francesco Bertini. "Boundary Layer Development on a High-Lift LP Turbine Profile Under Passing-Wakes Conditions." In ASME Turbo Expo 2009: Power for Land, Sea, and Air. ASMEDC, 2009. http://dx.doi.org/10.1115/gt2009-59889.
Full textAbstract:
The boundary layer development on the suction side of a high-lift LP turbine profile has been experimentally investigated under steady and unsteady flow conditions in the range of Reynolds numbers between 70000 and 300000. Upstream wake periodic perturbations are generated by means of a tangential wheel of radial rods. The paper reports the results of the investigations performed for both steady and unsteady inflow cases (reduced frequency f+ = 0.62) for Re = 300000 and Re = 70000, representative of nominal and reduced Reynolds number operating conditions, respectively. A phase-locked ensemble-averaging technique has been employed to reconstruct the phase-averaged velocity and unresolved unsteadiness boundary layer profiles from the hotwire instantaneous velocities. Phase sequences of the boundary layer development, as well as time-space plots of velocity and unresolved unsteadiness in normal and streamwise directions highlight the complex wake/boundary layer interaction mechanism. While at the larger test Reynolds number the wake/boundary layer interaction does not substantially influence the transition process, at the lower test Reynolds number the boundary layer wake receptivity triggers the transition process, strongly attenuating the large separation bubble occurring at steady conditions.
9
Sayma, Abdulnaser I. "Steady-Flow Analysis of Low Pressure Compression System for Turbofan Engines." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27625.
Full textAbstract:
This paper has two main objectives. It first aims at presenting a method of prescribing boundary conditions for the steady-state flow simulations of low pressure compression systems for turbofan engines. The methodology is generic and it can be applied for steady and unsteady flow simulations of numerous similar multi-component applications. The basic idea is to extend the flow domain upstream to the far field and downstream beyond the first set of stator vanes, both in the bypass and core, where variable area nozzles are used. Fixed static pressure boundary conditions are used downstream of the nozzles which are representative of downstream blockage. With such an approach, the need to prescribe accurate boundary conditions immediately upstream and downstream of the fan is eliminated. An iterative approach is then used to obtain the correct bypass ratio. The second objective of the paper is to demonstrate the use of the methodology in mapping out the loss loop for the outflow guide vanes (OGV) and examine its effects on fan performance. Wherever possible, predictions were checked against measured data and good overall agreement was obtained.
10
Mao, Shuo, Ridge A. Sibold, Stephen Lash, Wing F. Ng, Hongzhou Xu, and Michael Fox. "Experimental Study of the Endwall Heat Transfer of a Transonic Nozzle Guide Vane With Upstream Jet Purge Cooling: Part 1 — Effect of Density Ratio." In ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14814.
Full textAbstract:
Abstract Nozzle guide vane platforms often employ complex cooling schemes to mitigate ever-increasing thermal loads on endwall. Understanding the impact of advanced cooling schemes amid the highly complex three-dimensional secondary flow is vital to engine efficiency and durability. This study analyzes and describes the effect of coolant to mainstream blowing ratio, momentum ratio and density ratio for a typical axisymmetric converging nozzle guide vane platform with an upstream doublet staggered, steep-injection, cylindrical hole jet purge cooling scheme. Nominal flow conditions were engine representative and as follows: Maexit = 0.85, Reexit/Cax = 1.5 × 106 and an inlet large-scale freestream turbulence intensity of 16%. Two blowing ratios were investigated, each corresponding to upper and lower engine extrema at M = 3.5 and 2.5, respectively. For each blowing ratio, the coolant to mainstream density ratio was varied between DR = 1.2, representing typical experimental neglect of coolant density, and DR = 1.95, representative of typical engine conditions. An optimal coolant momentum ratio between = 6.3 and 10.2 is identified for in-passage film effectiveness and net heat flux reduction, at which the coolant suppresses and overcomes secondary flows but imparts minimal turbulence and remains attached to endwall. Progression beyond this point leads to cooling effectiveness degradation and increased endwall heat flux. Endwall heat transfer does not scale well with one single parameter; increasing with increasing mass flux for the low density case but decreasing with increasing mass flux of high density coolant. From the results gathered, both coolant to mainstream density ratio and blowing ratio should be considered for accurate testing, analysis and prediction of purge jet cooling scheme performance.