bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on the sensitivity of steam ejector simulation to wall treatment methods
Authors: Cao Zhengqing , Fang Kaiyue , Zhang Xinchen , Yang Xuelong 
Published: March 2024

Abstract
Considering the importance of turbulence model and wall treatment to steam ejector simulation, the influence of five wall treatment methods on numerical results was studied based on the realizable k-ε turbulence model (RKE). Combined with experimental data and SST turbulence model, the prediction of complex flow phenomena inside the ejector, including shock wave and reflux, by different wall treatment methods is discussed. The results show that under the numerical simulation conditions, the enhanced wall treatment method (EWT) combined with the RKE model can better predict the injection coefficient of the steam ejector, and the relative error compared with the experimental data is 5.3%. The standard wall function method (STWF) ignores the influence of the viscous bottom layer, resulting in inaccurate simulation of the internal flow phenomenon of the injector, and the injection coefficient calculated by the simulation is 10.2% higher than the experimental value. The results of the non-equilibrium wall function (NWF) method are relatively indifferent to the experimental values, and are not recommended when simulating steam ejectors.
Optimized design of steam ejector primary nozzle based on orthogonal test method
Authors: Fang Kaiyue , Cao Zhengqing , Zhang Xinchen , Yang Xuelong 
Published: March 2024

Abstract
This paper proposes an orthogonal test method to optimize the design parameters of a steam ejector. The objective of this method is to improve the cooling system’s efficiency and effectiveness. The L9(33) orthogonal table was established to simultaneously optimize the shape curve of the converging portion of the primary nozzle, the length of the throat, and the angle of the diverging portion, and the entrainment rate and the critical backpressure were used as the performance indexes to formulate 9 groups of test schemes with a total of 108 cases, which were simulated under the same conditions. Based on Computational Fluid Dynamics (CFD) technology, the influence order of the three parameters is derived by polar analysis and the flow field is analyzed at the overall as well as the primary nozzle. The results show that the shape curve of converging portion of the primary nozzle is a sensitive factor affecting the performance of the ejector, which should be emphasized in practical production applications; the Mach number shapes at the primary nozzles of different structures show similarity and overlap at a distance of about 0.03 m from the mixing chamber. The Mach number profiles at different back pressures show want similarity.
Investigation of the film cooling performance of ceramic matrix composites plate with different braided structures
Authors: Zhu A L , Tu Z C , Mao J K , Zhao C W 
Published: March 2024

Abstract
The ceramic matrix composite (CMC) materials have been gradually applied in the high temperature components, due to its excellent heat resistance and mechanical performance. The CMC component still need cooling to protect its safe operation in the high temperature environment of aero engine, such as film cooling structure. This study focuses on the influence of braided structure on the film cooling effect over a three-dimensional braided CMC plate. The full-size calculation model reflecting the internal mesoscale structure of CMC plate was established. The thermal properties of fibers and matrix are also introduced in mesoscale. The geometric parameter which is braided angle of braided structure is changed in different models, to analyze its impacts on the comprehensive film cooling effect. The results show that the fiber bundles inside the CMC plate are the main heat transfer channel, due to its relatively higher thermal conductivity. The different braided angles affect the anisotropic thermal conductivity of CMC on the three main directions. There exists an optimal braided angle near 40° that maximizes the heat dissipation effect in the region near the film cooling holes. While in the downstream region away from holes, the influence of braided angle is weak.
Numerical study of the heterogeneous condensation effect on the steam turbine performance
Authors: Zhang Guojie , Wang Xiaogang , Ye Jianming , Jin Zunlong , Dykas Sławomir 
Published: March 2024

Abstract
The investigation of the loss and efficiency of steam turbine holds immense significance in improving the production of electric energy as a pivotal power conversion device in the electric power industry. However, during the expansion of steam in the steam turbine, the existence of heterogeneous particles leads to the heterogeneous condensation, resulting in a significant reduction in the turbine efficiency and safety of its operation. This study investigates the impact of heterogeneous condensation flow on the performance of steam turbines. First, a condensation model is developed, and numerical calculations are performed using the Bakhtar stator blade cascade. The validity of the proposed model is verified by comparing its results with existing experimental data. Then, the adiabatic flow (non-condensing), the homogeneous condensation flow, and the heterogeneous condensation flow on solid particles with a radius of 10-8[m] and particle concentration of 1015 and 1016[1/kg] are employed to investigate the effect of each flow type on steam turbine performance, and the loss, power, and efficiency in the turbine are detailedly and quantitatively calculated. The results show that in the presence of heterogeneous particles, increasing particle concentration appropriately can effectively reduce the loss caused by condensation and improve thermal efficiency.
Research on pressure-regulating device based on different combination layouts, slopes and sprinkler interval distances
Authors: Zhao Yuxia , Liu Junping , Wen Xingbin , Zhao Yanyan 
Published: March 2024

Abstract
To improve the water application uniformity for sprinkler irrigation on sloping land, a new type of pressure-regulating device was designed. The pressure regulation device was installed between the pipe and the inlet of the sprinkler to regulate the pressure gradient. In this study, PIPENET software was used to simulate the installation of pressure regulation device on the corresponding PY10 sprinklers and analyze the working modes of each sprinkler in the irrigation system. The simulation considered factors such as sprinkler combination layout, ground slope and sprinkler interval distance, with average application rate and uniformity coefficient as evaluation criteria. The results showed that the installation of pressure regulation device reduced the pressure difference between each sprinkler. Under these conditions, irrigation uniformity was improved. The research results indicate that integrating different sprinkler layouts, ground slopes and sprinkler interval distances significantly improved the effectiveness of pressure-regulating device installation in hilly areas. This study provided a reference for addressing poor irrigation uniformity in sloping land in hilly areas.
Leakage detection based on variational mode decomposition and long short-term memory neural network
Authors: Zheng Shumin , Yan Jianguo , Xu Yan , Li Jiang 
Published: March 2024

Abstract
In the process of long-term continuous operation, fluid transportation pipelines are prone to leakage accidents. Therefore, this study investigates the detection of small-sized leaks with a leakage aperture of 13 mm in pipes with a diameter of 100 mm. The experimental investigation is conducted under the following operating conditions: volume flow of 25-80 m3/h, pressure of 100-200 kPa. The variations in volume flow and pressure signals during leak occurrences are analysed. To mitigate the interference caused by noise, the variational mode decomposition (VMD) method is introduced. The VMD effectively reduces noise interference in the signals. Furthermore, the denoised signals are utilized to establish a long short-term memory neural network (LSTM). The LSTM model achieves a high accuracy rate of 91.67% for the entire dataset.
Experimental study on multiple characteristics of multi-source AE signals during cavitation process of waterjet propulsion pump
Authors: Feng Chao , Zhu Hualun , Tao Jin , Yang Mengzi 
Published: March 2024

Abstract
In order to investigate the cavitation-induce acoustic emission (AE) characteristics of a waterjet propulsion pump, a synchronous experimental system consisting of a test pump, a high-speed camera, and acoustic emission sensors has been established. The characteristic parameters of AE signals are extracted to established the quantitative relationships between cavitation status and AE signals. These characteristic parameters mainly consist of the ringing count rate Rc
, energy release rate Er
, and Hurst index Hi
. The cavitation status of the test pump is reflected in the characteristic parameters of the AE signals obtained by the sensors installed at different locations. The incipient blade suction side (SS) cavitation as well as the blade tip gap cavitation can be detected through the change of characteristic parameters of AE signals at impeller inlet. The start of head drop can be reflected by the variety of characteristic parameters of AE signals at impeller middle. Large-scale cavitation will lead to the breakdown of pump performance and dramatically characteristic parameters’ change of AE signals can be measured by the sensors located at impeller outlet.
Research on flow field quality measurement of super high speed circulating water channel based on LDV
Authors: Geng H H , Wang Z L , Zhu J S , Liu T Y , Zhu H L , Zou X 
Published: March 2024

Abstract
The flow field quality of the super high speed circulating water channel (SHSCWC) test section in the open (with a free liquid surface state) and closed (with a cavitation tunnel state) was studied. An array of flow field measuring points was established to measure the axial velocity using a laser doppler velocimeter (LDV) for both states. Meanwhile, ultrasonic sensors were used to measure the levelness of the free liquid surface in the test section. The measurement results indicated that in the open state, the non-uniformity and instability of 8 kinds of flow velocity in the flow field section are less than 1.0%, respectively, while the free liquid surface level is less than 25mm at the flow rate of 8m/s. In the closed state, the non-uniformity and instability of eight types of flow velocity in the flow field section are all below 1.0%, with turbulence being less than 0.5%. The measurement results in both states meet the requirements of technical indicators, and provide data support for the experimental research and optimal design of the SHSCWC.
Optimal flow control of vortex breakdown in a laminar swirling flow
Authors: Seifi Zeinab , Raisee Mehrdad , Cervantes Michel J 
Published: March 2024

Abstract
In highly swirling flows, such as hydraulic turbines operating under part-load (PL) conditions, vortex breakdown occurs and performance is impaired. Consequently, it is imperative that mitigation measures are taken. In the present study, a laminar swirling flow with a vortex breakdown at a Reynolds number of 180 is investigated. At the inlet, a swirling velocity profile with a swirl number of 1.095 is set. A stability analysis is conducted to identify unstable modes based on the assumption that vortex breakdown is a global instability. The results indicate that spiral modes with wave number 1 are unstable. An optimal flow control method based on the Adjoint method is then utilized to mitigate vortex breakdown. In the present study, the control method targets vorticity using a minimization algorithm. Control variables include radial and axial body forces. According to the results, the method was effective in mitigating vortex breakdown. A stability analysis conducted during the control process revealed that as the vorticity decreased, the growth-rate of the eigenvalue decreased, indicating that the flow is stabilized.
Reduced-order modelling of unsteady cavitating flow around a Clark-Y hydrofoil
Authors: Zhang F , Liu Y Q , Wu Q , Huang B , Wang G Y 
Published: March 2024

Abstract
This paper proposes a novel approach that combines Proper Orthogonal Decomposition (POD) reduced-order system with Long Short-Term Memory (LSTM) neural network to predict flow velocity. Large Eddy Simulation (LES) is used to simulate the cavitating flow around a NACA66 hydrofoil. POD is adopted to reduce the dimensionality of the high-dimensional data. It was found that 66.81% of the flow field energy and dominant coherent structures can be captured with first eight POD modes. The LSTM network model was further used to predict the temporal data of the POD mode coefficients, and the error of the predicted coefficients was within an acceptable range. The reconstructed flow field agrees well with the real flow field and the cavitation development has also been well illustrated. This method provides a promising and efficient alternative for flow prediction and has potential for applications in fluid dynamics, aerospace engineering, and hydrodynamics.
Numerical simulation of the unsteady flow mechanism and dynamic characteristics around cascade
Authors: Zhu J , Bao W C , Liu S H , Zheng H W , Zhang M D 
Published: March 2024

Abstract
Research on the flow mechanism and dynamic characteristics of a cascade comprising three NACA hydrofoils was conducted under varying cavitation numbers and angles of attack. This study serves as a theoretical foundation for the high-speed miniaturization of fluid machinery. Drawing upon prior findings on individual hydrofoils, comparisons were made regarding the cavitation characteristics of the cascade versus a single hydrofoil, emphasizing pressure and velocity distributions in the flow field. Results suggest that while the cascade consists of three hydrofoils, their interactions profoundly influence the flow field. The cavitation phenomena in the cascade diverge considerably from that of a single hydrofoil. Multiple hydrofoils cause a low-pressure region to appear in the middle of the cascade, making it more susceptible to cavitation flow compared to a single hydrofoil. However, interactions among the hydrofoils constrain the expansion of this low-pressure zone, rendering the cavitation flow in the cascade’s middle layer more stable. As the angle of attack rises, the cavitation flow around the cascade undergoes notable changes, with varying cavitation flows at different cascade positions. The upper layer experiences cavitation flow akin to that of a single hydrofoil. In contrast, the middle layer sustains a thin, weakly periodic cavitation flow.
Numerical simulation and experiment of a blade management device in microgravity
Authors: Chen L , Li Y , Liu J T , He X M , Qu Z , Yang N J 
Published: March 2024

Abstract
Currently, most satellite propulsion systems are mainly chemical propulsion, and liquid propellant is the necessary power fuel for the propulsion system. The working environment of microgravity occurs when the satellite is in orbit. According to the working characteristics of the satellite, a propellant management device of vane type is designed. The PMD is composed of a vertical guide plate and a liquid accumulator, which is applied to the propellant tank to store and manage the propellant. In this paper, the microgravity gas-liquid management and control mechanism of a propellant management device of vane type is studied by numerical simulation and tower drop test. The results of numerical simulation and tower drop test are consistent, which verifies the good fluid management characteristics of this type of propellant management device, and provides references for its engineering application and the design of this type of structure.
Design of a high-speed cavitation hydrodynamics test system
Authors: Zhang Jiayun , Yao Zhifeng , Zhong Qiang , Ren Haitao , Xiao Ruofu , Wang Fujun 
Published: March 2024

Abstract
Due to the high sediment content in rivers in China and the relatively high concentration of “gas core” in water, cavitation of hydraulic machinery is likely to occur at high speeds, leading to a series of problems such as reduced efficiency of hydraulic machinery, intensified vibration and material erosion. To carry out the study of cavitation erosion, a test system (hereinafter referred to as the cavitation water tunnel) suitable for the basic study of cavitation dynamics at high velocity is designed in this paper. The whole system includes a circulating loop structure, which mainly consists of a suction chamber, contraction rectifier, and test section. The test section is convenient for observing different types of cavitation flow fields inside and the highest test velocity in the test section can exceed 35 m/s. A water-gas separation chamber is designed to collect bubbles over 100 microns to ensure that the inlet of the test section is not affected by cavitation. The functions of the test system include basic experiments such as flow field characteristics, cavitation dynamics, acoustic characteristics, and cavitation erosion characteristics around hydrofoils/blades, which can provide test conditions for the study of high-speed hydrodynamic characteristics such as pumps/turbines, propellers and underwater vehicles.
Impeller optimization using a machine learning-based algorithm with dynamic sampling method and flow analysis for an axial flow pump
Authors: Song Xueyi , Li Ying , Huang Renfang , Luo Xianwu 
Published: March 2024

Abstract
Design optimization for widely used axial flow pumps presents a formidable challenge due to the significant impact of numerous parameters associated with impeller geometry on hydraulic performance. The expansive design space raises concerns about the cost and time implications of the optimization process. This paper introduces a machine learning-based algorithm with a dynamic sampling approach to enhance the hydraulic performance of axial flow pumps. The focus is on an axial flow pump designed for China’s South-to-North Water Diversion Project. Optimization involves selecting 15 design variables governing impeller geometry, considering meridional shape and mean blade profiles. The optimization process predicts hydraulic performance using CFD methods, with a primary objective of maximizing efficiency at the axial flow pump’s design point while maintaining pump head around the design value. The results indicate that the proposed machine learning-based algorithm exhibits commendable convergence, delivering a notable improvement in performance. For instance, the optimized axial flow pump displays 2% efficiency increase compared to the initial design. Further analysis employing concepts like entropy generation rate and boundary vorticity flux reveals that the optimized pump has more uniform flow near the pressure side of the impeller blade. Additionally, design optimization effectively suppresses flow separation at the blade trailing edge near the impeller hub. This study offers valuable insights and a practical tool for the design optimization of axial flow pumps.
Monitoring and Early Warning for Hydroelectric Generating Sets based on Hotelling’s T2 and LSTM Model
Authors: Sun Yuxin , Xu Zhuofei , Sun Longgang , Wang Tong , Li Dian 
Published: March 2024

Abstract
A method of monitoring and early warning for hydroelectric generating sets based on Hotelling’s T-squared statistics(T2) and Long Short-Term Memory(LSTM) network is proposed. Multi-channel vibration and swing signals can be fused and predicted based on the given model. The monitoring and alerting function can also be implemented according to a threshold value of T2. First, the vibration and swing signals of multi-channels hydroelectric generating sets are obtained and fused based on Principal Component Analysis(PCA) to reduce the amount of data. Second, Hotelling’s T2 statistics under normal running state is calculated and taken as a warning threshold. Third, a LSTM model is established to predict future values of T2, and early warning for a hydroelectric generating set can be realized by use of the obtained warning threshold. The vibration and swing signals from 16 channels in a set are used to validate the effectiveness of the method. Finally, there is a more than 90% reduction in the amount of data and the efficiency is significantly improved. LSTM has a high accuracy in T2 prediction and realize the early warning for abnormal status.
Study on the permeability behaviour of hydrogen doped natural gas in polyethylene pipeline
Authors: Li Xiang , Shao Puzhen , Wang Jun , Huang Liuyi , Dong Zhi , Zhong Fengping 
Published: March 2024

Abstract
The use of non-metallic PE pipes to transport hydrogen energy can avoid the problem of hydrogen embrittlement in metal pipes, but due to material characteristics, PE pipes exhibit gas leakage behavior. Therefore, this article conducted a study on the permeability of polyethylene (PE100) as a gas pipeline material for hydrogen-doped gas, mainly analyzing the effects of hydrogen content and gas pressure on the permeability of PE100 gas. We ensure that the raw materials are uniform and free from pore defects through microstructure observation and industrial CT characterization. The experimental results show that with the increase of hydrogen content in the hydrogen-doped gas, the gas permeability coefficient of the sample significantly increases. When the hydrogen content is 60%, the gas permeability coefficient increases by 83% compared to when no hydrogen is added. Further increase in hydrogen content results in no significant change in the gas permeability coefficient; As the gas pressure increases, the gas permeability coefficient of the s ample gradually decreases. This study will provide data support for the safe transportation of hydrogen energy and promote the development of the hydrogen energy industry.
Optimization of the active element and reinforcement proportion for improving joint strength of brazed Si3N4/42CrMo
Authors: Wang Tianpeng , Sun Mingcheng , Wang Yunan , Wang Zhongyu , Xia Yongfeng , Zhang Jie 
Published: March 2024

Abstract
Micron-TiN particles and Ti powder were introduced into the AgCu powder filler to design a particle-reinforced composite filler. This TiN particle (TiNp) modified brazing material was adopted to reliably braze Si3N4 ceramics onto 42CrMo steel, and the ratio of active element Ti to TiNp reinforcement was optimized for joint strength improvement. The reaction layer’s thickness (TiN+Ti5Si3) adjacent to the ceramic decreased by introducing TiNp. Nevertheless, the reaction layer’s thickness (TiC) at the 42CrMo side did not vary too much. TiNp showed excellent wettability with Ag-Cu-Ti braze, and there was no obvious reaction at the interface. Cu-Ti intermetallic compounds were formed and randomly distributed in the brazing seam. When the TiNp content did not exceed 8 vol.%, the joints’ mechanical properties first sharply decreased and then remained basically unchanged when Ti increased. Raising the TiNp content to 10 vol.%, the joint strength showed the changing trends of first increasing and then dropping by increasing Ti content. The bending strength reached the maximum value of 396 MPa when 8 vol.% TiNp and 4 wt.% Ti were adopted.