Добірка наукової літератури з теми "Stream traced inlet"
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся зі списками актуальних статей, книг, дисертацій, тез та інших наукових джерел на тему "Stream traced inlet".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Статті в журналах з теми "Stream traced inlet"
1
DONG, HAO, CHENG-PENG WANG, and KE-MING CHENG. "EXPERIMENTAL AND NUMERICAL INVESTIGATION OF HYPERSONIC JAWS INLET." Modern Physics Letters B 24, no. 13 (May 30, 2010): 1409–12. http://dx.doi.org/10.1142/s0217984910023748.
Повний текст джерелаАнотація:
In order to obtain the flow field characteristics and the influence of boundary layer, numerical simulations and wind tunnel tests are conducted for two streamline traced Jaws inlets at Mach number 7. The inlets are designed based on a flow field with 8-7 planar shock wave (the ramp in pitch plane is inclined at 8° to the free stream and in yaw plane is inclined at 7° to the free stream, yielding planar shocks). In the study, the static pressure distributions were measured and analyzed along the plane-symmetric centerline of the inlet with and without the boundary layer correction, respectively. Results show that boundary layer correction can obviously weaken the viscous influence to the inlet, increasing the mass flow coefficient and improving total pressure recovery.
2
Wennrich, V., A. Francke, A. Dehnert, O. Juschus, T. Leipe, C. Vogt, J. Brigham-Grette, P. S. Minyuk, and M. Melles. "Modern sedimentation patterns in Lake El'gygytgyn, NE Russia, derived from surface sediment and inlet streams samples." Climate of the Past 9, no. 1 (January 22, 2013): 135–48. http://dx.doi.org/10.5194/cp-9-135-2013.
Повний текст джерелаАнотація:
Abstract. Lake El'gygytgyn/NE Russia holds a continuous 3.58 Ma sediment record, which is regarded as the most long-lasting climate archive of the terrestrial Arctic. Based on multi-proxy geochemical, mineralogical, and granulometric analyses of surface sediment, inlet stream and bedrock samples, supplemented by statistical methods, major processes influencing the modern sedimentation in the lake were investigated. Grain-size parameters and chemical elements linked to the input of feldspars from acidic bedrock indicate a wind-induced two-cell current system as major driver of sediment transport and accumulation processes in Lake El'gygytgyn. The distribution of mafic rock related elements in the sediment on the lake floor can be traced back to the input of weathering products of basaltic rocks in the catchment. Obvious similarities in the spatial variability of manganese and heavy metals indicate sorption or co-precipitation of these elements with Fe and Mn hydroxides and oxides. But the similar distribution of organic matter and clay contents might also point to a fixation to organic components and clay minerals. An enrichment of mercury in the inlet streams might be indicative of neotectonic activity around the lake. The results of this study add to the fundamental knowledge of the modern lake processes of Lake El'gygytgyn and its lake-catchment interactions, and thus, yield crucial insights for the interpretation of paleo-data from this unique archive.
3
Wennrich, V., A. Francke, A. Dehnert, O. Juschus, T. Leipe, C. Vogt, J. Brigham-Grette, P. S. Minyuk, and M. Melles. "Modern sedimentation patterns in Lake El'gygytgyn, NE Russia, derived from surface sediment and inlet streams samples." Climate of the Past Discussions 8, no. 3 (June 1, 2012): 2007–39. http://dx.doi.org/10.5194/cpd-8-2007-2012.
Повний текст джерелаАнотація:
Abstract. High Arctic Lake El'gygytgyn/NE Russia holds a continuous 3.58 Ma sediment record, which is regarded as the most long-lasting climate archive of the terrestrial Arctic. Based on multi-proxy geochemical, mineralogical and granulometric analyses of surface sediment, inlet stream and bedrock samples, supplemented by statistical methods, major processes influencing the modern sedimentation in the lake were investigated. Grain-size parameters and chemical elements linked to the input of feldspars from acidic bedrock indicate a wind-induced two-cell current system as major driver of sediment transport and accumulation processes in Lake El'gygytgyn. The distribution of mafic-rock related elements in the sediment on the lake floor can be traced back to the input of weathering products of basaltic rocks in the catchment. Obvious similarities in the spatial variability of manganese and heavy metals indicate sorption or co-precipitaion of these elements with Fe and Mn hydroxides and oxides. But the akin distribution of organic matter content might also point to a fixation to organic components. An enrichment of mercury in the inlet streams might be indicative of neotectonic activity around the lake. The results of this study add to the fundamental knowledge of the in-lake processes of Lake El'gygytgyn and its lake-catchment interactions, and thus, yield crucial insights for the interpretation of paleo-data from this unique archive.
4
He, Xuzhao, Jialing Le, and Si Qin. "Design and analysis osculating general curved cone waverider." Aircraft Engineering and Aerospace Technology 89, no. 6 (October 2, 2017): 797–803. http://dx.doi.org/10.1108/aeat-12-2014-0214.
Повний текст джерелаАнотація:
Purpose Waverider has high lift to drag ratio and will be an idea aerodynamic configuration for hypersonic vehicles. But a structure permitting aerodynamic like waverider is still difficult to generate under airframe’s geometric constrains using traditional waverider design methods. And furthermore, traditional waverider’s aerodynamic compression ability cannot be easily adjusted to satisfy the inlet entrance requirements for hypersonic air-breathing vehicles. The purpose of this paper is to present a new method named osculating general curved cone (OCC) method aimed to improve the shortcomings of traditional waveriders. Design/methodology/approach A basic curved cone is, first, designed by the method of characteristics. Then the waverider’s inlet captured curve and front captured tube are defined in the waverider’s exit plane. Osculating planes are generated along the inlet captured curve and the designed curved cone is transformed to the osculating planes. Streamlines are traced in the transformed curved cone flow field. Combining all streamlines which have been obtained, OCC waverider’s compression surface is generated. Waverider’s upper surface uses the free stream surface. Findings It is found that OCC waverider has good volumetric characteristics and good flow compression abilities compared with the traditional osculating cone (OC) waverider. The volume of OCC waverider is 25 per cent larger than OC waverider at the same design condition. Furthermore, OCC waverider can compress incoming flow to required flow conditions with high total pressure recovery in the waverider’s exit plane. The flow uniformity in the waverider exit plane is quite well. Practical implications The analyzed results show that the OCC waverider can be a practical high performance airframe/forebody for hypersonic vehicles. Furthermore, this novel waverider design method can be used to design a structure permitting aerodynamic like waverider for a practical hypersonic vehicle. Originality/value The paper puts forward a novel waverider design method which can improve the waverider’s volumetric characteristics and compression abilities compared with the traditional waverider design methods. This novel design approach can extend the waverider’s applications for designing hypersonic vehicles.
5
Hall Jr., Robert O., and Hilary L. Madinger. "Use of argon to measure gas exchange in turbulent mountain streams." Biogeosciences 15, no. 10 (May 18, 2018): 3085–92. http://dx.doi.org/10.5194/bg-15-3085-2018.
Повний текст джерелаАнотація:
Abstract. Gas exchange is a parameter needed in stream metabolism and trace gas emissions models. One way to estimate gas exchange is via measuring the decline of added tracer gases such as sulfur hexafluoride (SF6). Estimates of oxygen (O2) gas exchange derived from SF6 additions require scaling via Schmidt number (Sc) ratio, but this scaling is uncertain under conditions of high gas exchange via bubbles because scaling depends on gas solubility as well as Sc. Because argon (Ar) and O2 have nearly identical Schmidt numbers and solubility, Ar may be a useful tracer gas for estimating stream O2 exchange. Here we compared rates of gas exchange measured via Ar and SF6 for turbulent mountain streams in Wyoming, USA. We measured Ar as the ratio of Ar : N2 using a membrane inlet mass spectrometer (MIMS). Normalizing to N2 confers higher precision than simply measuring [Ar] alone. We consistently enriched streams with Ar from 1 to 18 % of ambient Ar concentration and could estimate gas exchange rate using an exponential decline model. The mean ratio of gas exchange of Ar relative to SF6 was 1.8 (credible interval 1.1 to 2.5) compared to the theoretical estimate 1.35, showing that using SF6 would have underestimated exchange of Ar. Steep streams (slopes 11–12 %) had high rates of gas exchange velocity normalized to Sc=600 (k600, 57–210 m d−1), and slope strongly predicted variation in k600 among all streams. We suggest that Ar is a useful tracer because it is easily measured, requires no scaling assumptions to estimate rates of O2 exchange, and is not an intense greenhouse gas as is SF6. We caution that scaling from rates of either Ar or SF6 gas exchange to CO2 is uncertain due to solubility effects in conditions of bubble-mediated gas transfer.
6
Marttila, H., S. Tammela, K. R. Mustonen, P. Louhi, T. Muotka, H. Mykrä, and B. Kløve. "Contribution of flow conditions and sand addition on hyporheic zone exchange in gravel beds." Hydrology Research 50, no. 3 (February 27, 2019): 878–85. http://dx.doi.org/10.2166/nh.2019.099.
Повний текст джерелаАнотація:
Abstract We conducted a series of tracer test experiments in 12 outdoor semi-natural flumes to assess the effects of variable flow conditions and sand addition on hyporheic zone conditions in gravel beds, mimicking conditions in headwater streams under sediment pressure. Two tracer methods were applied in each experiment: 2–5 tracer-pulse tests were conducted in all flumes and pulses were monitored at three distances downstream of the flume inlet (0 m, 5 m and 10 m, at bed surface), and in pipes installed into the gravel bed at 5 m and 10 m distances. The tracer breakthrough curves (total of 120 tracer injections) were then analysed with a one-dimensional solute transport model (OTIS) and compared with data from the gravel pipes in point-dilution pulse tests. Sand addition had a strong negative effect on horizontal fluxes (qh), whereas the fraction of the median travel time due to transient storage (F200) was determined more by flow conditions. These results suggest that even small additions of sand can modify the hyporheic zone exchange in gravel beds, thus making headwater streams with low sediment transport capacity particularly vulnerable to sediments transported into the stream from catchment land use activities.
7
Su, He, Pei Wu, Jing Xue, Yongan Zhang, and Haijun Zhang. "Analysis of flow field characteristics and structure optimization of the split-stream rushing muffler for diesel engine." Noise Control Engineering Journal 68, no. 1 (January 20, 2020): 101–11. http://dx.doi.org/10.3397/1/37688.
Повний текст джерелаАнотація:
In order to analyze the flow field characteristics of the split-stream rushing muffler, a theoretical model describing the velocity of the split streams is established and verified by the tracer test. For this new-principle muffler, the acoustic performance and the relationship between the velocity drop of the airflow and the pressure field are analyzed, also the structure optimization of the muffler is carried out based on the orthogonal test. Finally, a new muffler is fabricated based on the designing theory of this type of muffler for a prototype of diesel engine, and the comparative analyses are conducted compared with its original muffler. The results show that the establishment and analysis of the theoretical model for velocity during the split-streams rushing process are correct. In the frequency range of 0â–“1000 Hz, the average transmission loss of split-stream rushing muffler is better than that of the original muffler. While the speed of airflow is reduced by split-streams rushing, a certain pressure loss is caused at the same time, which is about 50% of total pressure loss of the muffler, and the average fluid resistance coefficient of the split-stream rushing process is 0.91. Compared to the original muffler of the sample engine, the average insertion loss of the optimized new muffler is increased by 61.2%. At inlet air velocity of 30 m/s, the pressure loss is reduced by 16.8%. The results provide a potential for practical engineering application of this new split-stream rushing muffler in future.
8
Henríquez, Felipe, Luis Maldonado, Juan Yianatos, Paulina Vallejos, Francisco Díaz, and Luis Vinnett. "The Use of Radioactive Tracers to Detect and Correct Feed Flowrate Imbalances in Parallel Flotation Banks." J 5, no. 2 (June 12, 2022): 287–97. http://dx.doi.org/10.3390/j5020020.
Повний текст джерелаАнотація:
This work presents the application of radioactive tracers to detect and correct feed flowrate imbalances in parallel rougher flotation banks. Several surveys were conducted at Minera Los Pelambres concentrator, in banks consisting of 250 m3 mechanical flotation cells. The feed pulp distribution was estimated from the mean residence times, which were obtained from residence time distribution measurements. The tracer was injected in the feed distributor and the inlet and outlet tracer signals of cells 1 and 2 were measured by on-stream sensors. The baseline condition for the pulp distribution was defined by the valve settings in the feed distributor, which led to an unbalanced condition for two parallel rougher banks, with 34% of the pulp being fed to bank A and 66% to bank B. New valve configurations were evaluated, with a fraction of the feed being directed to the rougher bank C, which was not initially fed from the same distributor. The feed distribution was finally balanced with 49% of the pulp being fed to bank A versus 51% to bank B. Thus, the radioactive traces proved to be a powerful tool to industrially detect and improve feed distributions in parallel flotation circuits.
9
Temnerud, J., A. Düker, S. Karlsson, B. Allard, K. Bishop, J. Fölster, and S. Köhler. "Spatial patterns of some trace elements in four Swedish stream networks." Biogeosciences Discussions 9, no. 5 (May 15, 2012): 5719–53. http://dx.doi.org/10.5194/bgd-9-5719-2012.
Повний текст джерелаАнотація:
Abstract. Four river basins in Southern Sweden, catchment size 0.3 to maximum 127 km2 (median 1.9), were sampled in October 2007. The 243 samples were analysed for 26 trace elements (Ag, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Ga, Ge, In, La, Li, Mo, Ni, Pb, Sb, Se, Sn, Tl, Ti, U, V and Zn) to identify spatial patterns within drainage networks. The sampling design made it possible to compare the difference between 40 stream reaches, 53 stream junctions with 107 tributaries vs. downstream reaches and 36 lakes with 77 inlets vs. outlets comparisons. The largest concentration differences (at reaches, junctions and lakes) were observed for lakes, with outlets usually having lower concentration compared to the inlets for As, Ba, Be, Bi, Cd, Co, Cr, Ga, Ge, Ni, Pb, Sn, Ti, Tl, U, V and Zn. Significantly lower concentrations were observed for Co and Cd when comparing headwaters with downstream sites in each catchment. We found no evidence for elevated concentration of heavy metals Cd, Cu, Zn or Pb in the two acidified areas of South-west Sweden. Common factor analysis revealed that As, Bi, Cr, Ga, Ge, Tl, V co-vary positively with Al, Fe and total organic carbon (TOC) and negatively with La, Li and pH. A better understanding of the quantitative removal of organic carbon and iron will aid in understanding metal fluxes from landscapes rich in organic matter and iron.
10
Kjellstrand, R., A. Mattsson, C. Niklasson, and M. J. Taherzadeh. "Short circuiting in a denitrifying activated sludge tank." Water Science and Technology 52, no. 10-11 (November 1, 2005): 79–87. http://dx.doi.org/10.2166/wst.2005.0681.
Повний текст джерелаАнотація:
The presence of a short circuit flow in a denitrifying activated sludge tank was identified and modelled. Tracer tests with pulse addition of lithium salt were used to investigate the hydraulics of the tank. The lithium concentration in the effluent was detected and residence time distribution (RTD) curves were generated. Hydraulic models based on completely stirred tank reactors (CSTRs) in series were generated from the RTD curves and the models were compared. The short circuit problem was successfully described using the Martin model, where the inflow is divided into two strands. Each strand was modelled as a number of CSTRs in series. At a normal flow the results of the model show that the tank has 12.8% dead volume, 85.8% main volume and 1.3% short circuiting volume. The inflow was divided into 91.9% entering the main volume and 8.1% entering the short circuiting volume. The mean velocity of the short circuiting stream was estimated to 0.4m/s. At maximum flow the short circuiting stream was even larger and handled 24.3% of the flow. The short circuiting stream was identified in the upper part of the tank due to the position of the inlet and the outlet. The configuration of a tank including the use of baffles, the geometry of the inlet and mixer configuration should be considered carefully if short circuiting is to be avoided.
Дисертації з теми "Stream traced inlet"
1
Harrland, Alan. "Hypersonic inlet for a laser powered propulsion system." Thesis, 2012. http://hdl.handle.net/2440/79072.
Повний текст джерелаАнотація:
The idea of laser powered lightcraft was first conceptualised in the early 1970's as a means of launching small scale satellite payloads into orbit at a much lower cost in comparison to conventional techniques. Propulsion in the lightcraft is produced via laser induced detonation of the incoming air stream, which results in the energy source for propulsion being decoupled from the vehicle. In air breathing mode the lightcraft carries no onboard fuel or oxidiser, allowing theoretically infinite specific impulses to be achieved. Recently interest has been renewed in this innovative
technology through cross-continent and industry research programs aimed at making laser propulsion a reality. In a ground launched satellite, the vehicle must travel through the atmosphere at speeds greatly in excess of the speed of sound in order to achieve the required orbital velocities. Supersonic, and in particular hypersonic, flight regimes exhibit complicated physics that render traditional subsonic inlet design techniques inadequate. The laser induced detonation propulsion system requires a suitable engine configuration that offers good performance over all flight speeds and angles of attack to ensure the required thrust is maintained throughout the mission. Currently a hypersonic inlet has not been developed for the laser powered lightcraft vehicle. Stream traced hypersonic inlets have demonstrated the required performance in conventional hydrocarbon fuelled scramjet engines. This design technique is applied to the laser powered lightcraft vehicle, with its performance evaluated against the traditional lightcraft inlet design. Four different hypersonic lightcraft inlets have been produced employing both the stream traced inlet design methodology, and traditional axi-symmetric inlet techniques. This thesis outlines the inlet design methodologies employed, with a detailed analysis of the performance of the lightcraft inlet at angles of attack and off-design conditions. Fully three-dimensional turbulent computational fluid dynamics simulations have been performed on a variety of inlet configurations. The performance of the lightcraft inlets have been evaluated at differing angles of attack. An idealised laser detonation simulation has also been performed to verify that the lightcraft inlet does not unstart during the laser powered propulsion cycle.Thesis (M.Phil.) -- University of Adelaide, School of Mathematical Sciences, 2012
Частини книг з теми "Stream traced inlet"
1
Allison, Penelope M. "House I 10,2–3." In The Insula of the Menander at Pompeii. Oxford University Press, 2007. http://dx.doi.org/10.1093/oso/9780199263127.003.0029.
Повний текст джерелаАнотація:
According to Elia, this area had been a ‘cubiculum’, that was later adapted as a ‘bottega’ or ‘taberna’ and decorated in the Fourth Style. Remains of painted plaster on the walls suggest that the decoration had been cursory. An L-shaped masonry counter ran west from the east door jamb of the entrance, and then south. It was plastered and painted red, decorated with plants, and had two dolia inset into the centre of the southern branch. At the southern end of this bench was a masonry fornello, of which only the base and east wall was extant at the time of excavation. Disturbed volcanic deposit was encountered 2.5 m above the pavement. The only loose finds were made on the counter. They consisted of three bronze coins, one Republican and one dating to ad 37–8. The fixtures in this area, and the graffiti at the entrance to the house, have been used as evidence that this was a shop for the heating and dispensing of food. The apparent state of the fornello suggests that it was not in use at the time of the eruption. Loose finds may have been removed after the eruption, as suggested by the breaches in the walls, or possibly during clearing of the façade. However, the complete lack of recorded finds supports an inference that it was not operating as a going concern prior to the eruption. Similar conditions were observed by Berry for the so-called ‘caupona’ in House I 9,11, from which she concluded that it was not functioning in ad 79. This entranceway led to hall 4, off which most of the rooms in this house opened. Ling notes evidence of wall plaster but no decoration was recorded by Elia. In the east wall, 1.15 m above the floor and 0.82 m from the south end, was a semi-circular lararium niche with traces of a protecting door and an associated inscription: ‘Lares Augusti’. Disturbed volcanic deposit was encountered 2.5 m above the pavement of this entranceway. The finds from the actual entrance consisted of iron fragments, which would have been part of the closing system for the street door, and a marble base.
Тези доповідей конференцій з теми "Stream traced inlet"
1
Chi, Zhongran, Haiqing Liu, Shusheng Zang, Chengxiong Pan, and Meibao Zhang. "Full-Annulus URANS Study of Inlet Hot-Streak Transportation in a Four-Stage Gas Turbine." In ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75596.
Повний текст джерелаАнотація:
Nonuniformity of combustor-exit-flow temperature, also named hot-streak, could strongly increase the complexity in unsteady flow and heat transfer of gas turbine cascades. Detailed investigation into the hot-streak transportation in multi-stage gas turbine should provide a valuable reference to both fault diagnosis of combustors based on the distribution of turbine exhaust temperature. In this study, transportation of hot-streaks inside a four-stage gas turbine was numerically investigated using three-dimensional (3D), Unsteady Reynolds Averaged Navier-Stokes equations (URANS) Computational Fluid Dynamics (CFD) study with simulation domain including eight full-annulus cascades. The two-dimensional (2D) temperature fields at the rotor-stator interfaces and turbine exit was acquired by the full-annulus URANS CFD, and then discussed through comparing the circumferential and radial distributions and also the ranges of time-dependent fluctuations. The time-average temperature distributions were analyzed by Discrete Fourier Transform (DFT) method in circumferential direction to characterize the distribution. The URANS CFD results show that the hot-streaks could travel through the entire turbine and result in nonuniformity of turbine exhaust temperature. The rotor-stator interaction could change the 2D shape of hot-streaks and intensity the time-dependent fluctuation of flow temperature. DFT results show that the typical frequencies of circumferential temperature distribution are coinciding with the number of hot-streaks and the blade number of upstream/ downstream cascades. The DFT results also indicated that the hot-streaks migrate 35°∼45° in the circumferential direction, and the maximal relative amplitude of hot-streaks is reduced from 28% to 5%. The redistribution of hot/cold fluid in stator cascade could affect the mixing of hot-streaks depending on clocking position.
2
Hoerzer, Klaus, Hermann Haselbacher, Anthony J. Griffiths, Nick Syred, and Thomas A. Fraser. "CFD-Analysis of the Combustion in the Primary Stage of a Two-Stage Combustion Chamber." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30610.
Повний текст джерелаАнотація:
Combustion of wood powder may be applied in a two-stage multi-inlet combustion chamber. The primary stage of the combustion chamber has tangential air inlets to provide high swirl flow. The wood powder and its conveying air enter the gasification chamber axially through a center inlet in the bottom. The aim of the investigation was the analysis of the combustion flow of the primary stage of the combustion chamber. The calculation grid was three-dimensional and unstructured. Turbulence was modelled with the Reynolds-Stress-Model, species with mixture fraction/pdf-approach, radiation with the P1-model. Postprocessing has been done for particle tracks, the temperature distribution and tangential velocity distribution and for the species distributions of solid carbon, carbon monoxide, carbon dioxide and oxygen as well.
3
Gallardo, S., V. Abella, and G. Verdu´. "TRACE5 Simulation of Condensation-Induced Water Hammer Phenomena." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-30057.
Повний текст джерелаАнотація:
The purpose of this work is to test the capability of TRACE5 code in the simulation of thermal-hydraulic transients concerning Condensation-Induced Water Hammer (CIWH) phenomena in a horizontal branch pipe connected to the vessel downcomer. The CIWH is produced by the condensation of the steam by subcooled water counterflow in the horizontal pipe, which causes two-phase flow interfacial instability, and is capable of initiating a severe water hammer, possibly leading to significant plant damage. The work is developed in the frame of OECD/NEA ROSA Project Test 2, performed in the Large Scale Test Facility (LSTF) of the Japan Atomic Energy Agency (JAEA) [1]. The purpose is to provide an analytical model for the LSTF installation, in order to evaluate the critical inlet water flow rates and system pressures of CIWH in a long horizontal pipe without using interfacial friction factor or heat transfer coefficients and using the default TRACE criterion of transition from stratified to a slug flow. The analytical model is designed with the thermal-hydraulic code TRACE5 via 1D-components, reproducing the actual branch where the CIWH is produced. A TEE component is connected to a FILL component, which simulates the water injection, and to a BREAK component set to the boundary conditions that simulate the downcomer. Our model uses one-dimensional flow equations and default correlations of interfacial shear stress and heat and mass transfer available by TRACE. Several comparisons are performed, varying pressure system and water injection mass flow rates. Simulated pressure pulses are characterized, studying parameters such as geometry nodalization, time-step effect, Courant number, numerical diffusion, etc. Results show that 1D model slightly underestimates the maximum pressure pulse intensity in all cases considered.
4
Casaday, B., R. Prenter, C. Bonilla, M. Lawrence, C. Clum, A. Ameri, and J. P. Bons. "Deposition With Hot Streaks in an Uncooled Turbine Vane Passage." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95108.
Повний текст джерелаАнотація:
The effect of hot streaks on deposition in a high pressure turbine vane passage was studied both experimentally and computationally. Modifications to Ohio State’s Turbine Reaction Flow Rig allowed for the creation of simulated hot streaks in a four-vane annular cascade operating at temperatures up to 1093°C. Total temperature surveys were made at the inlet plane of the vane passage, showing the variation caused by cold dilution jets. Deposition was generated by introducing sub-bituminous ash particles with a median diameter of 11.6 μm far upstream of the vane passage. Results indicate a strong correlation between surface deposits and the hot streak trajectory. A computational model was developed in Fluent to simulate both the flow and deposition. The flow solution was first obtained without particulates, and individual ash particles were subsequently introduced and tracked using a Lagrangian tracking model. The critical viscosity model was used to determine particle sticking upon impact with vane surfaces. Computational simulations confirm the migration of the hot streak and locations susceptible to enhanced deposition. Results show that the deposition model is overly sensitive to temperature and can severely overpredict deposition. Model constants can be tuned to better match experimental results, but must be calibrated for each application.
5
Marciniak, Vincent, Marco Longhitano, and Edmund Kügeler. "Assessment of Transition Modeling for the Design of Controlled Diffusion Airfoil Compressor Cascades." In ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94864.
Повний текст джерелаАнотація:
The aim of this paper is to investigate whether correlation-based transition models can be used for the design of CDA profiles. To this end, a CDA compressor cascade has been widely experimentally investigated at DLR Cologne. Off-design measurements have been carried out and the influence of the variation of four flow parameters has been investigated: The inlet Mach number, the incidence, the chord-based Reynolds number and the free-stream turbulence intensity. The inlet Mach number has been varied from 0.5 up to 0.8. The incidence was varied over the whole working range and beyond. Realistic values of the Reynolds number and of the free-stream turbulence intensity have been attained. Hence, the test case apt to assess the capacity of the DLR’s in-house turbomachinery specific CFD code TRACE to design modern compressor blades. In this paper, computations simulating the influence of those four parameters on the performance of the CDA profile are presented and compared to the measurements. Two transition models are used for this study: an in-house model denoted MultiMode model and the γ-ReΘ model. In addition, two turbulence models (Wilcox k-ω and Menter k-ω SST) and their turbomachinery extensions have also been used for this study. The results between the different numerical simulations and the measurements are discussed in term of loss coefficients and Mach number distributions. The computed losses are close to the experimental values and the physics of the flow is also well reproduced. Bypass transition as well as laminar separation bubbles have been simulated in accordance with the experimental observations. Hence, the TRACE code is able to predict the onset of transition over a wide range of flow conditions.
6
IKPEZE, Victoria Kamnetochi, John Olusoji OWOLABI, Idowu Iyabo OLATEJU, and Abdulwahab GIWA. "Modelling and Simulation of Acid Gas Absorption from Natural Gas by Amine Solution Using Aspen HYSYS." In SPE Nigeria Annual International Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/207183-ms.
Повний текст джерелаАнотація:
Abstract This work has been carried out to model and simulate a typical acid gas absorption process using Aspen HYSYS process simulator. The chemical components involved in the process development were water, methane, ethane, propane, higher alkanes, carbon dioxide, hydrogen sulphide, nitrogen and amines: monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA) and methyldiethanolamine (MDEA). The fluid package selected for the simulation before entering the simulation environment was Acid Gas – Chemical Solvents. In the simulation environment, the model was developed by picking an absorber from the Model Palette, placing it and assigning the input and the output streams involved before inputting the parameters required for model convergence. The carbon dioxide-rich feed gas was made to enter the absorber at the bottom inlet stream while the lean amine stream entered at the top inlet and showered down on the uprising gas thereby trapping the carbon dioxide molecules within the gas. The top product from the absorber was the treated gas while the amine solution and the trapped carbon dioxide left the absorber as the bottom product. Different simulations were run to investigate the performance of the amines under the same operating conditions. It was discovered that, of all the four amine solvents considered in this work for the removal of carbon dioxide by chemical absorption, MEA had the highest efficiency but would require more dehydration because it had the highest water content. DEA was also found to scrub the carbon dioxide down to acceptable levels. However, TEA and MDEA barely scrubbed any carbon dioxide under these conditions, as their carbon dioxide compositions were found to be unacceptable. The analyses of the results obtained from the simulations indicated that Aspen HYSYS can be used to study the process of acid gas absorption successfully.
7
Cação Ferreira, Tânia S., and Tony Arts. "Influence of Gas-to-Wall Temperature Ratio on By-Pass Transition." In ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/gt2017-63524.
Повний текст джерелаАнотація:
An investigation of thermal effects on bypass transition was conducted on the highly-loaded turbine guide vane LS89 in the short-duration isentropic Compression Tube (CT-2) facility at the von Karman Institute for Fluid Dynamics (VKI). Measurements from high response surface-mounted thin films coupled with analog circuits provided the time-resolved wall heat flux history whereas pneumatic probes, differential pressure transducers and thermocouples allowed the accurate definition of the inlet and outlet flow conditions. The gas-to-wall temperature ratio, ranging from 1.11 to 1.55, was varied by changing the inlet total temperature. The isentropic exit Mach number ranged from 0.90 to 1.00 and the global freestream turbulence intensity value was set at 0.8, 3.9 and 5.3%. The isentropic exit Reynolds number was kept at 106. The onset of transition was tracked through the wall heat flux signal fluctuations. Within the present operating conditions, no significant effect of the gas/wall temperature ratio was put in evidence. At the present (design) transonic exit conditions, the local free-stream pressure gradient appears to remain the main driver of the onset of transition. A wider range of operating conditions must be considered to draw final conclusions.
8
Haustein, Herman D., Wilko Rohlfs, Faruk Al-Sibai, and Reinhold Kneer. "Development of Heat Transfer in a Two-Dimensional Wavy Falling Film of Water and its Influence on Wave Stability." In ASME 2013 Heat Transfer Summer Conference collocated with the ASME 2013 7th International Conference on Energy Sustainability and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ht2013-17453.
Повний текст джерелаАнотація:
Heat exchangers employing falling films are relevant to a multitude of industrial applications using water-based liquids. In the present study, periodic, two-dimensional waves are imposed by excitation on a vertically falling film of water, which is then heated by a uniform heat flux, within the laminar and transitional flow range (39<Re<200). Liquid-film thickness is measured by confocal chromatic imaging and surface temperature is measured by high-speed IR thermography. As the 2D waves travel downstream they destabilize in the spanwise direction and evolve 3D structures (bumps). Further wave destabilization, under relatively low heating, was observed to coincide with the appearance of local thermal flows (“hot streaks”), though no deformation of the liquid surface could be measured. These flows are understood to be induced by thermo-capillary forces, which in extreme cases are known to lead to the formation of rivulets, film rupture and heater burnout. Understanding these initial stages of thermo-capillary flow is crucial to its suppression. Analysis of the thermal images reveals several significant streamwise length scales: a thermal inlet length based on the emergence of the thermal boundary layer (Lt), a thermal inlet length based on reaching thermally developed conditions (Lh), and the length at which “hot-streaks” first appear (Ls). In addition the dominant (most unstable) spanwise wavelength of the hot streaks, Lz, was identified through FFT analysis of the thermal profile beyond Ls. First the independence of the thermal inlet lengths from the heat-flux was established. Next, the influence of the nominal flow conditions (Reynolds number and excitation frequency) on Lt, Lh and Lz was examined — thereby extending the range of previous studies to higher Reynolds numbers. The thermal inlet lengths Lt and Lh were found to increase with flow rate, whereas they had opposing trends with regard to frequency. Lz consistently decreased with an increase of the flow rate, as smaller (turbulent) scales became more dominant, and it was found to be indifferent to excitation frequency over a wide range. Some future directions and methods of hot streak suppression are discussed, as well.
9
Copeland, Colin D., Peter Newton, Ricardo Martinez-Botas, and Martin Seiler. "The Effect of Unequal Admission on the Performance and Loss Generation in a Double-Entry Turbocharger Turbine." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22212.
Повний текст джерелаАнотація:
The current work investigates a circumferentially-divided turbine volute designed such that each gas inlet feeds a separate section of the turbine wheel. Although there is a small connecting interspace formed between the nozzle and the mixed flow rotor inlet, this design does well to preserve the exhaust gas energy in a pulsed-charged application by largely isolating the two streams entering the turbine. However, this type of volute design produces some interesting flow features as a result of unequal flows driving the turbine wheel. To investigate the influence of unequal flows, experimental data from the turbocharger facility at Imperial College has been gathered over a wide range of steady-state, unequal admission conditions. These test results show a significant drop in turbine performance with increasing pressure difference between inlets. In addition, the swallowing capacities of each gas inlet are interdependent, thus indicating some flow interaction between entries. To understand the flow physics driving the observed performance, a full 3-D CFD model of the turbine was created. Results show a highly disturbed flow field as a consequence of the non uniform admission. From these results, it is possible to identify the regions of aerodynamic loss responsible for the measured performance decrease. Given the unequal flows present in a double-entry design, each rotor passage sees an abrupt change in flow conditions as it rotates spanning the two feeding sectors. This operation introduces a high degree of unsteady flow into the rotor passage even when it operates in steady conditions. The amplitude and frequency of this unsteadiness will depend both on the level of unequal admission and the speed of rotor rotation. The reduced frequency associated with this disturbance supports the evidence that the flow in the rotor passage is unsteady. Furthermore, the CFD model indicates that the blade passage flow is unable to fully develop in the time available to travel between the two different sectors (entries).
10
Prenter, Robin, Ali Ameri, and Jeffrey P. Bons. "Computational Simulation of Deposition in a Cooled High-Pressure Turbine Stage With Hot Streaks." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-57815.
Повний текст джерелаАнотація:
Ash particle deposition in a high-pressure turbine stage was numerically investigated using steady (RANS) and unsteady (URANS) methods. An inlet temperature profile consisting of Gaussian non-uniformities (hot streaks) was imposed on the vanes, with vane cooling simulated using a constant vane wall temperature. The steady case utilized a mixing plane at the vane-rotor interface, while a sliding mesh was used for the unsteady case. Corrected speed and mass flow were matched to an experiment involving the same geometry, so that the flow solution could be validated against measurements. Particles ranging from 1 to 65 μm were introduced into the vane domain, and tracked using an Eulerian-Lagrangian tracking model. A novel particle rebound and deposition model was employed to determine particles’ stick/bounce behavior upon impact with a surface. Predicted impact and capture distributions for different diameters were compared between the steady and unsteady methods, highlighting effects from the circumferential averaging of the mixing plane. The mixing plane simulation was found to over predict impact and capture efficiencies compared with the unsteady calculation, as well as over predict particle temperature upon impact with the blade surface. Blade impact efficiencies increased with higher Stokes numbers in both simulations, with multiple rebounds occurring on the pressure surface in the mixing plane case, and on the suction surface in the unsteady case.
Звіти організацій з теми "Stream traced inlet"
1
Regan, Jack, Julie Bryant, and Craig Weinschenk. Analysis of the Coordination of Suppression and Ventilation in Single-Family Homes. UL Firefighter Safety Research Institute, March 2020. http://dx.doi.org/10.54206/102376/slzh7498.
Повний текст джерелаАнотація:
Prior full-scale research with the fire service was primarily designed to isolate specific tactics, most often either ventilation or suppression, which allowed researchers to develop science-based recommendations related to the specific components of fireground operations studied in relatively controlled conditions. The current project went beyond earlier research by conducting twenty experiments in eight acquired, single-family residential structures and that combined fireground tactics to quantify the impact of coordination between ventilation and suppression actions. This experimental series included second-story bedroom fires (14 experiments) and first-floor kitchen fires (6 experiments). The main control variables studied included the position of initial application of water, the ventilation method, and the timing of ventilation relative to water application. The ventilation tactics examined in these experiments included horizontal, vertical, positive pressure, and hydraulic ventilation, while the suppression tactics included both interior water application and initial exterior water application followed by interior water application. While some elements of the experiments (e.g. structure floor plan and weather) resulted in increased variability, the lessons learned highlighted the importance of having a systematic approach to the implementation of tactics. Most importantly, there was no meaningful increase in temperature outside of fire rooms when ventilation tactics were executed in coordination with (shortly after or shortly before) the onset of suppression. The effectiveness of suppression actions in extinguishing the fire were dependent on the ability of those actions to 1) cool surfaces in the fire room and 2) wet unburned fuel. Exterior suppression actions on second-floor bedroom fires resulted in a decrease in temperatures throughout the second floor, followed by regrowth prior to final suppression through interior streams. When exterior suppression was performed on first-floor kitchen fires, where more complete fuel wetting was possible, regrowth was not observed prior to interior suppression. When surface cooling or fuel wetting are not possible due to the elevation of the fire room, missing ceiling, or obstacles, firefighters should consider alternative means of water distribution to improve the effectiveness of suppression actions from outside the fire room. Suppression actions, whether interior or exterior, generally resulted in a decrease in temperatures and gas concentrations at locations where occupants may potentially be located. Conditions improved most quickly at locations closest in proximity to the inlet of the flow path established between the front door and the fire room. For this reason, opening an exterior door to gain access should be thought of as an important ventilation action, both in terms of its potential to cause fire growth and its potential to improve conditions for potentially trapped occupants. After effective suppression, structure ventilation operations should similarly be cognizant of gas flows, with the aim of establishing flow throughout all areas where occupants may be located.