bluuebunny/crossref_metadata_2025_split huggingface dataset:
CFD wind turbines wake effects by using UDF
Authors: Zhang Yi , Li Xuemin , Barasa Maulidi , Xu Weiming 
Published: June 2021

Abstract
The numerical simulation of wind turbine generators was carried out to investigate the relationship between wake expansion and distance of two wind turbine generators in a row. The commercial software ANSYS Fluent was used to perform the Computational Fluid Dynamics (CFD), and further, the standard k-ϵ turbulence modeling has been adopted to solve the steady-state, 3D Reynolds Averaged Navier-Stokes (RANS) equations. Results of near and far wake regions are analyzed. In fact, due to the squeezing effect of the wind turbine generators on the surrounding air, it is found that there is an acceleration area nearby the wind turbine rotors. The arrangement distance of wind turbine generators in a row is analyzed. The results show that as the arrangement distance of the wind turbine generators increases, the average wind speed and the wind power density in the acceleration area decrease. This conclusion has guiding significance for the arrangement of wind turbines in wind farms.
Explosion characteristic of stoichiometric syngas/air premixed gas in the flow state
Authors: Wang Baishi , Guo Pinkun , Wang Zhirong , Wang Xuxu , Liu Songjie , Xu Chuanqing , Chang Xinyue , Cao Xingyan , Wang Wei 
Published: June 2021

Abstract
With increasing attention to energy efficiency and environmental protection, syngas has attracted great interest as a clean fuel with broad development prospects. In order to further study the effect of the initial gas flow on the explosion of syngas, an explosion experiment of stoichiometric syngas/air premixed gas was carried out in a 3 × 3 × 100 cm square explosion pipe. The composition of the syngas used in the experiment is 50CO:50H2, the flow rate of the experiment gas is 0L/min-250L/min, and the Reynolds number (Re) is 0-9598.41. The experimental results show that the maximum explosion pressure Pmax and the maximum explosion pressure rise rate (dp/dt)max gradually increase with the increase of the initial flow rate and Re. The gas flow increases the flame area, and increase the combustion rate, thereby making the explosion more violent.
Prediction on Changes of Seabed due to Sluice Built on entrance of Haiyou Branch in Sanmen Bay
Authors: Shichang Huang , Xu Liu , Haiqian Han , Jinbin Mu , Haifeng Lou 
Published: June 2021

Abstract
Haiyou branch is the main branch of Sanmen Bay, it is an optional plan to construct sluice at the entrance of Haiyou branch to store fresh water for the utilization of freshwater resources in the Sanmen Bay basin. Basing on the verification of historical tidal currents and seabed erosion and deposition, numerical and physical models are established. Numerical calculations and physical model test show that the impact on hydrodynamic and seabed environment after the construction of sluice will be limited to the local sea area outside the sluice, where the downstream area of sluice, Shepan waterway and Maotou waterway are located, and the siltation strength decreases from the sluice towards Maotou waterway. After the construction of the sluice, the tidal inflow volume of Shepan section will decrease by 11.3% to 17.1%, the tidal volume of Maotou section decrease by 1.7% to 4.3%, and the tidal volume of Qinshan section and Qimen section remain basically unchanged. Within one year, the downstream area of sluice will be deposited with 0.5m∼0.7m, Maotou waterway with about 0.15m, and there is also little siltation at Qimen waterway and other waterway. Due to the impact of the sluice construction of Haiyou branch, after a long time, the deposition of deep pool in Maotou waterway is 2.0m∼2.5m. A once-in-50-year flood from the upper reaches will not cause significant seabed changes in the deep pool of Maotou waterway.
Research on evaluation index system of the operation efficiency in electricity market
Authors: Zhao Yuzhuo , Zhang Yanchi , Zhang Xinlin , Li He , Chen Dong , Xie Da 
Published: June 2021

Abstract
In order to ensure the efficient and stable operation of the electricity market, it is very important to set indexes to measure the market efficiency. In this paper, Herfindahl Hirschman Index (HHI) and social welfare index are used to measure the market efficiency. The article improves the traditional HHI. The HHI and social welfare index are standardized by min-max, and applied to a certain electricity market. The calculating results of each index and the result curve after standardization are given by example analysis.
Emergency Coordinated Frequency Control Strategy for Multi-DC Infeed Receiver Network
Authors: Li He , Zhang Yanchi , Chen Dong , Zhao Yuzhuo , Zhang Xinlin , Xie Da 
Published: June 2021

Abstract
For the receiver network with multiple DC feed-in, the DC locking fault seriously affects the safe and stable operation of the receiver network. This paper presents a frequency emergency coordinated control system which takes into account three measures: DC coordinated control, pumping and storage pump, and cutting off interruptible load. Two control strategies are developed, which are quick action from afar and frequency action on the spot. Both schemes have their own fault criteria. Finally, the two control strategies are analyzed and compared through the simulation of East China Power Grid.
Research on flow boiling in microchannel based on visualized flow patter
Authors: Wang Bingjun , Wang Jinfeng , Xie Jing , Yang Dazhang 
Published: June 2021

Abstract
Flow boiling in microchannel has become an effective solution for high-heat-flux cooling of electronic components and heat transfer equipment, research on flow boiling in microchannel benefits society. Visualization plays a key role in the research, flow patterns obtained by visualized tools contribute to the study of flow boiling in microchannels, it is embodied in the following two aspects: heat and mass transfer mechanism, flow pattern dynamics. Above two aspects are introduced and analysed so as to provide a reference for researchers who explore flow boiling in microchannels based on visualized flow patter.
Temporal and Spatial Changes of Land Use in Donghe District of Baotou City and Its Impact on Ecological Environment
Authors: Lv Jiankang , Sun Jianguo 
Published: June 2021

Abstract
Taking Donghe District, Baotou City, Inner Mongolia Autonomous Region as an example, research on land use change and its ecological environment response was carried out to provide theoretical support for the coordinated development of regional economy and ecological environment. Based on Landsat 4, 5 TM images from 1990 to 2010 and Landsat 8 OLI satellite remote sensing images from 2013 to 2018 to obtain land use maps, the land use transfer matrix explored the changes in land use and its ecological environment response in Donghe District from 1990 to 2018. The research results show that the urban development of Donghe District is gradually expanding to the northwest and southeast, and the area of residential and commercial service land has increased significantly in these two directions; the area of unused land has gradually decreased after soil improvement; the area of arable land has decreased in general; vegetation The area of the water body has gradually increased in recent years; the area of the water body has remained balanced as a whole. The quality of the ecological environment in Donghe District has improved.
Analysis on the causes of air pollution during the Spring Festival in Xi’an and the effectiveness of the government’s ban on fireworks
Authors: Jing Su , Yang Lin , Hongli Cao , Zhen Meng , Wei Li , Jiayi Hu 
Published: June 2021

Abstract
This paper analyzed the air pollution in view of the increasingly serious air pollution in Xi’an, this paper analyzes the air pollution in Xi’an, focused on the the effects of pollution source emission and meteorological conditions on ambient air quality. The results showed that the concentration of particulate matter decreased significantly during the Spring Festival with the increase of the ban on fireworks. In addition this paper combined with the public survey, discussed the necessity of banning fireworks and firecrackers, in order to provide ideas for the government to take feasible control measures in the work of pollution prevention and haze control.
Application and analysis of low temperature air source heat pump heating system in Cold Area
Authors: Wang Qiang , Zhu Xiaosheng , Liu Fengzhen , Zhang Wenke , Jiang Hongyang , Chen Shaojie 
Published: June 2021

Abstract
A low temperature air source heat pump (ASHP) heating system of residential building in cold area was designed and tested. The operating characteristics of the low temperature ASHP heating system in the typical day, typical month and the whole heating season were analyzed. The system energy saving performance in the whole heating season was also calculated. The results showed that the low temperature ASHP system operated stably in cold area and has energy-saving effect.
Analysis of Building Energy Saving Potential in High-speed Service Area Based on DeST Energy Consumption Simulation
Authors: Feng Ran , Gao Qingfei , Guan Xia , Du Peng , Jiang Hua , Zhang Lu , Wang Xu 
Published: June 2021

Abstract
High-speed service area buildings are located in specific areas and have special functions, so the research on energy consumption and energy-saving potential of high-speed service area buildings is different from that of conventional public buildings. In this paper, taking a high-speed service area building in Jinan as the research object, The dynamic benchmark model of hourly energy consumption of buildings in high-speed service area is established by using DeST energy consumption simulation software and the reference model is established. Comparing the annual energy consumption of the benchmark model with that of the reference model, this paper analyzes the energy-saving potential of the buildings in the high-speed service area.
Day-ahead sharing model of multi-integrated energy service providers based on source-load matching degree
Authors: Xu Weiting , Ma Ruiguang , Chen Chao , Wang Wei 
Published: June 2021

Abstract
The limited regulation capacity in the integrated energy community is a key factor restricting the development of the community-based integrated (distributed) energy system. Based on this, a model for optimal sharing of day-ahead energy in multi-communities considering the matching degree of source-load curves between communities is proposed. Firstly, the relationship between energy supply and multi-energy flow is analysed concretely in a single community. A mathematical model that includes electric vehicles and multiple energy conversion equipment is built, then, an objective function minimizing the cost of energy purchase, equipment operation and maintenance, and EV battery loss is established. Secondly, the comprehensive Spearman constant and Euclidean distance matching index based on photovoltaic and load data among the communities are considered to optimize the multi-community operation efficiency with the goal of minimizing the energy interaction cost. Finally, in a 3-community simulation system simulation, results show that the multi-energy sharing mode can effectively improve the overall economy of the system and the photovoltaic consumption capacity. The introduction of matching index also improves the energy transmission efficiency, verifying the rationality of the proposed model.
Research on Early Warning Model of Electric Vehicle Charging Safety
Authors: Jiang Linru , Zhang Yuanxing , Li Taoyong , Diao Xiaohong , Zhang Jing 
Published: June 2021

Abstract
At present, an effective evaluation system of the charging safety of electric vehicles has not been formed and lacks the corresponding safety early warning and protection control measures. It is of great significance to ensure the charging safety of electric vehicles and promote the rapid development of electric vehicles. Through the analysis of the establishment of the electric vehicle charging safety evaluation index system, the establishment method of the index system is studied. Finally, the demand analysis of the electric vehicle charging safety early warning and protection system is carried out. The function of establishing safety evaluation model in the system is clarified. For the comprehensive demonstration operation of electric vehicle, it is verified that the electric vehicle charging safety warning and protection system has real-time warning and protection function for battery, charging equipment and distribution network, which embodies the practical engineering value of the system.
Prediction of vortex precession in the draft tube of a model hydro turbine using mean field stability theory and stochastic modelling
Authors: Müller Jens S. , Sieber Moritz , Litvinov Ivan , Shtork Sergey , Alekseenko Sergey , Oberleithner Kilian 
Published: June 2021

Abstract
In this work we employ mean field stability theory (MFST) to predict the onset of the precessing vortex core (PVC) in the draft tube of Francis turbines. MFST is based on the linear stability analysis of the mean field of turbulent flows. Recent work shows that MFST very accurately predicts the formation of coherent structures in turbulent shear flows, such as the PVC. MFST may further reveal the flow regions that are most susceptible to flow actuation to suppress the PVC, which is of great practical relevance. In this work, MFST is accompanied by a data-driven approach to predict the linear growth rate of the PVC based on pointwise wall pressure measurements. The method is based on statistical evaluation of the probability density function of the PVC amplitude at limit cycle. It makes use of the intense noise induced by the background turbulence, which is expected to be a major driver of hydrodynamic instabilities. The empirical and analytic results are compared to phase-locked LDV measurements conducted inside the draft tube at various operating conditions, to assess the quantitative accuracy of the approach. The methodologies outlined in this work will be of relevance for future design of hydro turbines to run stable over a wide range of operating conditions.
CFD simulations of a Y-junction for the implementation of hydraulic short-circuit operating mode
Authors: Decaix J , Biner D , Drommi J-L. , Avellan F , Münch-alligné C 
Published: June 2021

Abstract
In the framework of the XFLEX HYDRO H2020 European Project, one of the demonstrators focuses on the implementation of the hydraulic short-circuit on the pump storage power plant of Grand-Maison owned by Electricité De France (EDF). The Grand-Maison power plant is a two-level plant production with one plant located above the downstream reservoir and equipped with four Pelton turbines; a second plant located downstream the reservoir and equipped with eight reversible pump-turbines. Hydraulic short circuit consists in running pumps and turbines in the meantime to balance the energy consumption of the pumps compared to the grid. Such an operating mode allows increasing the flexibility of the power plant and targeting the requirement of balancing the intermittent production due to the growing of new renewable energies such as wind and solar power plants. The hydraulic short-circuit operating mode leads to a change in the flow paths in the penstocks and junctions compared to the normal turbine or pump modes. Indeed, compared to the pump mode, this mode will lead to a flow derivation at the junction between the penstocks directed to the Pelton units and the penstocks directed to the upper reservoir. As this mode have not been scheduled at the beginning of the power plant construction, it is necessary to quantitatively assess the singular head losses generated at the junction to be able to simulate the complete behaviour of the power plant by means of a 1D model. CFD simulations are carried out with the Fluent software for several configurations of hydraulic short-circuit defined by the ratio of flow rate deviated to the Pelton turbines.
Assessment of advanced RANS turbulence models for the stability analysis of low specific speed pump-turbines
Authors: Del Rio A , Casartelli E , Mangani L , Roos D 
Published: June 2021

Abstract
Reversible pump-turbines, which can switch between pump and turbine operation, provide important support for the stabilization of the electrical grid. In order to fulfill their task, fast transition between the operation modes is required. This includes stable synchronization with the electrical grid during the process of turbine start at small guide vane openings (GVOs). However, the special geometry of pump-turbine impellers tends to produce unstable flow behavior, which can affect the synchronization process in a negative way.
The prediction of the stability behavior with the help of CFD during the design process is not yet fully developed. The simulation of small specific speed pump-turbines operating at small GVOs sets high requirements on the underlying numerical model. To capture all relevant flow structures accordingly, 3-dimensional unsteady computation of the entire pump-turbine domain is required. Further, it has been shown that turbulence modeling is a key factor in order to reproduce the 4-quadrant characteristic in the unstable S-shape region. Vortex structures in the vaneless space and runner channels are considered the root-cause for the occurring instabilities. Standard two-equation models are not able to predict the stability behavior under these difficult circumstances (highly separated flows, small specific speed, small GVO angle). Models, which consider the anisotropic behavior of Reynolds-stresses have shown to produce better results.
Considering the accurate prediction of mixing processes at off-design conditions, the focus was oriented to the anisotropy present in the turbulent structures. Standard models are often not sufficient to accurately predict vortices, which can have a huge impact on the performance, since based on the assumption of isotropic turbulence. Accordingly, they tend to dissipate and diffuse vortices too quickly. Improved models, which take the anisotropic nature of the Reynolds-stresses into account, can help in this context. The models can introduce the anisotropy via an explicit algebraic expression, or model directly the transport equations for the Reynolds-stresses. For this work the performance of a full Reynolds-stress model with improved coupling was investigated.
In order to obtain the predictions using advanced turbulence models a particularly robust framework based on a pressure-based fully coupled approach was used. The goal of this work is the development and testing of an improved full Reynolds-stress model for the application in the stability analysis of pump-turbines. The focus lies thereby on separation behavior and mixing/vortex dissipation.
MOC-CFD coupled model of load rejection in hydropower station
Authors: Mandair S , Morissette J F , Magnan R , Karney B 
Published: June 2021

Abstract
A modelling study investigates the consequences of transient flow conditions due to a turbine load rejection. The case study considers a large hydropower station with a long penstock. A three-dimensional (3D) Computational Fluid Dynamics (CFD) model is used to represent the spiral casing, guide vanes, runner, and draft tube. A one-dimensional (1D) Method of Characteristics (MOC) solver simulates water hammer in the penstock. The two models are coupled, to simulate a full load rejection. The results are compared with reference to field measurements and a pure 1D solver, combining the penstock and a turbine model based on machine and conveyance characteristics. A comparison of the high level data (head, flow, torque and rotational speed) reveals the two models reproduce the field data reasonably well. The exception being rotational speed toward the zero torque region, where both models underestimate speed. The model predicts high cycle pressure fluctuations on the turbine blade, which would produce serious mechanical loading. The source of the fluctuations is determined to be unstable vortices within the runner.
Assessment of turbulence models for the prediction of Bénard-Von Kármán vortex shedding behind a truncated hydrofoil in cavitation conditions
Authors: Chen Jian , Geng Linlin , De La Torre Oscar , Escaler Xavier 
Published: June 2021

Abstract
The transient cavitating flow in the wake of a hydrofoil at zero incidence angle has been simulated using a homogeneous mixture cavitation mass transfer model combined with both Reynolds Average Navier-Stokes (RANS) and Scale Resolving Simulation (SRS) turbulence models. The hydrofoil geometry corresponds to a 2D NACA 0009 with a truncated trailing edge which has already been extensively investigated in the High-Speed Cavitation Tunnel of the EPFL. The hydrodynamic conditions of interest correspond to a free stream velocity of 20 m/s (Re = 2 · 106) without cavitation and with two different degrees of cavitation. To improve the prediction of the vortex shedding behing the hydrofoil, the γ − Rθt
transitional boundary layer model has been coupled with the turbulence models. At cavitation-free regime, all the turbulence models with the exception of the SST and LES WALE ones have the ability to predict the experimentally measured vortex shedding frequency. Nevertheless, the results indicate that, neither the SST nor the DES-SST γ − Rθt
, can predict the vortex shedding frequency increase which has been experimentally observed when cavitation occurs. In contrast, the numerical results provided by the SST γ − Rθt
and the SSTCC γ − Rθt
show the capability to predict the expected shedding frequencies for both non cavitation and cavitation conditions. Beyond all expectation, the results provided by the LES WALE seem not only to overestimate the vortex shedding frequency at cavitation free conditions but also to underestimate the frequency when the cavitation number is significantly reduced.
Temporary shutdowns of the high-head run-of-river HPP Fieschertal to prevent excessive turbine erosion during floods
Authors: Felix D , Abgottspon A , Albayrak I , Boes R M 
Published: June 2021

Abstract
Hydro-abrasive erosion on hydraulic turbines is economically and energetically important. To better understand the causes and consequences of turbine erosion and to further develop mitigation measures, the suspended sediment concentration (SSC) and size distribution of mineral particles in the turbine water of the 64 MW high-head run-of-river hydropower plant (HPP) Fieschertal, Switzerland, have been continuously measured since 2012. An innovative combination of measuring techniques is used: turbidimeters, single-frequency acoustics, densimetry, laser diffraction and gravimetric analysis of water samples. Automatic warnings have been defined in the HPP’s control system to allow for systematic HPP shutdowns when the SSC in the valve chamber exceeds the threshold value of 10 g/l for at least 15 minutes. During the flood of July 29 and 30, 2017 with an SSC peak of 110 g/l, the intake was closed and the HPP was shut down for half a day. This prevented about 8000 tons of fine sediment from entering the HPP, which corresponds to 9 % of the turbines’ annual suspended sediment load (SSL) in 2017, or 12 % of the SSL in an average year without a significant flood. If the intake had been closed one hour earlier, the SSL could have been further reduced by about 3000 tons. For an earlier closing of the intake in case of floods, the turbidimeter at the intake shall be complemented by an additional instrument capable of measuring also medium to high SSC. Apart from the described flood event, SSC peaks in the range of 5 to 20 g/l occurring typically in late summer were attributed to re-suspension events in the storage tunnel due to HPP operation.