bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparative analysis of internal flow characteristics and particle trajectories of centrifugal pumps with different impeller structures under solid-liquid two-phase flow conditions
Authors: Chen Zhengsu , Heng Yaguang , Jiang Qifeng , Liu Tielin , Luo Xipeng 
Published: March 2024

Abstract
The disc pump is a non-conventional centrifugal pump that utilizes centrifugal force and boundary layer effects to transport fluids. This pump is widely used in industries such as petrochemicals. However, due to the presence of particles in the solid-liquid two-phase flow, it causes wear and performance degradation of the pump’s flow components. However, due to the presence of particles in the solid-liquid two-phase flow, it can cause wear and performance degradation of the pump components. To study the internal flow characteristics of solid-liquid flow and the particle trajectory in a bladed disc pump, numerical simulation method was adopted to perform steady-state numerical simulation of spherical particles with different diameters (0.1 mm, 0.25 mm, 0.4 mm) in the bladed disc pump. The results indicate that compared to conventional centrifugal pumps, the performance of the bladed disc pump is lower. The variation in particle diameter has a minor influence on the intensity of the internal flow field in the bladed disc pump. The particle trajectories inside the impeller of the bladed disc pump are more chaotic, with larger diameter particles exhibiting a wider range of trajectory variations, while smaller diameter particles maintain relatively stable motion trajectories.
Cavitation performance analysis and optimal design of the portable electric-driven axial flow pump
Authors: Tian Ding , Lu Rong , Zhu Han , Liu Jinfeng , Zhang Yong , Wei Guangjuan , Li Gangyuan , Si Qiaorui 
Published: March 2024

Abstract
Based on the ISIGHT optimization platform, the impeller parameterization modeling and simulation process of the portable axial flow pump is carried out through CFturbo, ICEM and CFX software, and the impeller is optimized with the help of multi-island genetic algorithm to target the two optimization objectives of efficiency and head. The optimization results show that the hydraulic efficiency increased by 6.3% under design conditions. At the same time, compared with the original solution, the optimized cavitation performance is significantly improved. Additionally, overall entropy production is significantly reduced. Field test results show that the head deviation is 1.42% and the efficiency deviation is 4.52% under design conditions, proving that the optimization results are reliable.
Pressure pulsation test of Wanjiazhai Francis turbine at different loads
Authors: Li Jinjun , Liu Qiang , Wang Weigang , Song Xijie , Wang Zhengwei , Zhu Di , Tao Ran 
Published: March 2024

Abstract
In this paper, the pressure pulsation of Wanjiazhai Francis turbine at six monitoring points under different loads is monitored. Fast Fourier Transform(FFT) was used to perform time-frequency conversion, and the data was analyzed from both time-domain and frequency-domain perspectives. From a time perspective, the pressure pulsation at the upstream bladeless area is the most sensitive to changes in power. From a frequency perspective, the frequency components of pressure pulsation are more complex when P=40kW, while the frequency domain diagrams of pressure pulsation at each monitoring point are similar when P=80kW and P=120kW.
Application of DMD method to eccentric self-excited vibration of tubular turbine runner
Authors: Wu Yanzhao , Hu Zilong , Zhu Di , Tao Ran , Xiao Ruofu 
Published: March 2024

Abstract
Tubular turbines are widely used in the development and utilization of low-head marine energy. The cantilever type runner inevitably leads to gap between the chamber and blade tip, and non-standard installation can easily lead to eccentric runner, affecting the safe and stable operation of turbine. The overall process of self-excited vibration is an obvious nonlinear process, so the applicability of traditional methods needs to be discussed. In recent years, reduced-order modelling methods based on linear dynamic systems have gradually been introduced into the analysis of hydraulic machinery, and have achieved certain results. Therefore, this study combines computational fluid dynamics (CFD) and dynamic mode decomposition (DMD) methods to conduct low-dimensional mode decomposition and comparative analysis of self-excited vibration caused by different runner eccentricities of tubular turbine. The research shows that as the runner eccentricity continues to increase, the modal frequency distribution of self-excited vibration becomes complex. The DMD method disassembles the low-level representations of self-excited vibration signals, greatly enriching the understanding of eccentric self-excited vibration of the runner, and providing assurance for the safe and stable operation of tubular turbines.
On improved active disturbance rejection controller design for a pumped storage hydro unit
Authors: Ding L H , Pei J 
Published: March 2024

Abstract
The pumped storage hydro unit (PSHU) shows bad dynamic performance because of the frequent switching of working conditions and the S-shaped characteristics of pump turbine. This paper proposes an improved fixed-time active disturbance rejection controller to improve the control performances and counteract the influences of uncertainties including modeling error and friction. A disturbance observer is designed to estimate the total uncertainty by using the information of the states and outputs, compensating the adverse effects of the total uncertainty actively by feed-forward principle as a result. The outstanding benefit of the disturbance observer lies in that it can be designed separately from the original controller and can enhance the performances of the PSHU without changing the original controller. Simulation results show that comparing with the conventional active disturbance rejection controller, the improved active disturbance rejection controller has better adaptability and higher robustness towards the system load disturbance, and the dynamic performance of the system is improved.
Numerical investigation of hydrodynamic damping of a pitching hydrofoil at different flow regimes
Authors: Bahrami Mohammad Amin , Raisee Mehrdad , Cervantes Michel J , Nourbakhsh Ahmad 
Published: March 2024

Abstract
Due to the development of intermittent renewable energy resources, hydropower plants are mostly operated under off-design conditions. This may lead to natural frequency excitation shortening the turbine life-span. To accurately estimate the fatigue life, it is necessary to evaluate the hydrodynamic damping parameters. In the present study, different flow regimes and their relationship with hydrodynamic damping are analyzed numerically using the γ - Reθt
transition SST ĸ - ω turbulence model. The test case is a NACA0009 hydrofoil pitching around its center of mass. A good agreement between the present and previous numerical results is obtained. Consistent with the literature, hydrodynamic damping coefficient demonstrate consistently two different regions. The phase shift between the displacement and moment increases with the rise of the pitching frequency. After reaching a peak value at a reduced frequency of around κ = 5, the phase shift starts to decrease, and eventually approaches zero again. The damping behavior demonstrates an opposite trend. First, it reduces in spite of the phase shift increase, and after the inflection point, where the flow field changes from the drag mode to the thrust mode, it rises due to the torque development. The maximum of the damping occurs at the low frequencies.
Active control of thermoacoustic oscillation based on the x-nlms algorithm
Authors: Zeng Qingwen , Hu Chunyan , Miao Keqiang , Sun Jiaxian 
Published: March 2024

Abstract
Thermoacoustic oscillations, caused by the coupling of unsteady heat release and pressure fluctuation, can result in severe damage to the combustion chamber of gas turbines. This paper presents a novel approach to active control of thermoacoustic oscillations, which is based on a Filtered-X normalized least mean square algorithm (X-NLMS). The controller employs the pressure magnitude at a predetermined axial position preceding the flame as the control variable, which is acquired through microphones installed around the combustor periphery. Control is accomplished by modifying the output frequency and phase of a loudspeaker. The performance of the control system is evaluated through simulations on a Rijke tube, with the classical PID method used as a comparison. The experimental results showcase the efficacy of the X-NLMS algorithm in actively controlling thermoacoustic oscillations. By adaptively estimating and attenuating pressure fluctuations, the algorithm effectively suppresses the undesired acoustic disturbances associated with thermoacoustic instabilities. Comparative analysis reveals that the X-NLMS algorithm outperforms PID control in terms of oscillation suppression and system stability. Its ability to adapt to time-varying dynamics and its low computational complexity make it a promising candidate for real-time thermoacoustic control applications.
Study of the effect of rotating channel rib structure on fuel flow and heat transfer characteristics
Authors: Dong Mengqiang , Huang Hongyan 
Published: March 2024

Abstract
Hypersonic vehicles can be affected by incoming hot air. In order to ensure that the power generation turbine blades can operate properly, the fuel in the engine is used to cool the turbine blades. In this paper, the heat transfer characteristics of fuel in smooth and 45° ribbed channels under rotating conditions are investigated. Their results show that, unlike the smooth channel, the heat transfer coefficient of the 45° ribbed channel decreases as Ro increases under the combined influence of the rib structure and the physical properties of the fuel. The rib structure disrupts the high-velocity fluid near the trailing surface of the centrifugal section, which promotes doping between the fuels and weakens the effect of the Coriolis force. The Nu increase in ribbed channels ranged from 11.4% to 55.1% compared to smooth channels.
A review of research on turbines for supercritical carbon dioxide power systems
Authors: Hu Zhuo , Jiang Hongsheng , Zhuge Weilin , Qian Yuping , Zhang Yangjun 
Published: March 2024

Abstract
Supercritical carbon dioxide (S-CO2) Brayton cycle has been known as a potential power cycle technology because of its high efficiency, compact structure and suitability for different heat sources. As one of the key components in the cycle, the turbine has an important impact on the cycle efficiency. Compared with traditional steam and gas turbines, S-CO2 turbines have high working pressure and small size. The internal flow characteristics are significantly different. In this paper, the research progress of S-CO2 turbines in recent years is reviewed. The design and performance evaluation methods for S-CO2 turbines of different types and power levels are summarized, and research on loss correlations and optimization algorithms are introduced. The features of flow field in S-CO2 turbines are discussed. Current studies mainly evaluate the flow field and flow losses through Computational Fluid Dynamics (CFD), and some studies further analyze the influencing mechanism of turbine geometric parameters on flow characteristics. The applications of multi-physical field analysis on S-CO2 turbines are also reviewed. The construction and operation of S-CO2 test loops, and relevant turbine experimental study findings are introduced. Future research directions of S-CO2 turbines are proposed.
Flow field prediction of S-shaped shock vectoring nozzle with rear deck based on deep learning
Authors: Miao Mingcong , Shi Jingwei , Liang Shuang , Wang Zhanxue , Zhou Li 
Published: March 2024

Abstract
The S-shaped shock wave vectoring nozzle with afterdeck can significantly improve the overall performance of the exhaust system, taking into account Thrust vectoring, infrared stealth and afterbody fusion. One of the technical difficulties in its design process lies in the complex flow field characteristics under different operating conditions. Currently, the mainstream method is to obtain nozzle flow field characteristics through CFD numerical simulation, but the CFD method is time-consuming and costly. Therefore, based on the depth learning principle, a depth Convolutional neural network based on U-NET framework is established to quickly predict the flow field of S-shaped shock wave vectoring nozzle with afterdeck. Using CFD data for training, the results show that the depth learning model has high prediction accuracy and can clearly predict the flow field characteristics inside the nozzle, especially the secondary flow and the complex wave structure near the afterdeck. The correction Coefficient of determination of the prediction model is greater than 0.97. And the time consumption is about 0.0689% of that of a conventional solver. It has good application prospects in quickly evaluating the flow field of S-shaped nozzles.
Experimental study on the internal temperature rise of a high-speed canned motor pump for liquid rocket engines
Authors: Wang Jiangning , Cai Guobiao , Yu Nanjia , Zhou Chuang , Gu Xiaoming , Cao Li 
Published: March 2024

Abstract
High-speed electric pumps are now gradually applied in liquid rocket engines. Compared with the pumps with dynamic seals, the canned motor pumps are more reliable, and thus suitable for delivering risky propellants. However, the partial flow diverted to the air-gap for cooling and lubrication faces the risk of overheating caused by its friction against the rotor. This paper performed an experiment on this issue with a high-speed canned motor pump for a notional rocket engine. Impellers with and without balance holes, as well as different configurations of jet holes, were adopted and their effects were analysed. Results showed that the internal temperature rise decreased by up to 78% when the balance holes were removed, and decreased by up to 40% when the jet hole configuration was modified. Both factors influenced the internal temperature rise by varying the flow rate of the cooling recirculation. The study suggested that the high-speed canned motor pump should be designed with an appropriate flow rate of the cooling recirculation, so as to control the temperature rise of the propellant and ensure safe operation of the rocket engine.
Effect of surface roughness on lubrication performance of water-lubricated bearing for energy recovery turbocharger
Authors: Ning Yanqiang , Zhang Desheng , Li Yan , Ye Xiaoyan , Ding Jingfei 
Published: March 2024

Abstract
In this study, the lubrication performance of the water-lubricated bearing of the energy recovery turbocharger was studied considering the surface roughness. By simulating the rough surface of the bearing with the Weierstrass-Mandelbrot function and combining the water film thickness equation, Reynolds average equation, Greenwood-Tripp contact model and motion equation, the theoretical model of water-lubricated bearing is established and its solution is developed. The variational rules for the hydrodynamic pressure and force, asperity contact pressure and force, and other performance parameters of the water lubricated bearings during start-up and stable operation were obtained by solving this model, and the effect of different surface roughness on the start-up performance and steady operation lubrication performance is studied. The results show that the hydrodynamic force increases rapidly and the asperity contact force sharp decreases during the early start-up stage, and the smaller the surface roughness, the faster the hydrodynamic increase and asperity contact force decrease. The thickness distribution and pressure distribution of water film with different surface roughness have slight differences in stable operation. Therefore, the surface roughness has an important effect on the lubrication performance of the water lubricated bearing in the start-up stage, but has little effect on the stable operation.
Control of separated flow at low Reynolds number around NACA0012 airfoil by boundary layer suction
Authors: Wang A , Lai H 
Published: March 2024

Abstract
The separated flow at low Reynolds number around the NACA0012 airfoil is numerically studied by large-eddy simulation. Strategies of boundary layer suction to control flow separation are investigated. A method of using two-zone suctions, near the leading edge and near the trailing edge, are calculated. Based on verification with direct numerical simulation (DNS) and experimental data, the results of the lift and the drag, the vortices, and the strength of near-field pressure fluctuations, are checked. The results show that the two-zone suctions can supress flow transition and separation, thereby increase the lift and reduce the drag. The shedding of vortices is weakened, and the near-field pressure fluctuations are attenuated. For comparison with the two-zone suctions, the strategies of suction near the leading edge only and suction near the trailing edge only are also studied. It is found that suction near the leading edge only may suppress transition and delay separation when the suction zone is large enough, but the flow property deteriorates due to shedding vortices in the wake. The suction near the trailing edge only may improve the flow performance by reducing the size of the vortices in the rear section of the airfoil and in the wake region, but it has little effect on the separation bubble and transition.
Compressed air energy storage system: Effect of variable relative stator installation angle on nozzle governing turbine performance
Authors: Guan Yin , Li Wen , Zhu Yangli , Wang Xing , Zhang Yifeng , Chen Haisheng 
Published: March 2024

Abstract
The air storage pressure of compressed air energy storage system gradually decreases during the process of energy release, and a reasonable air distribution method for the turbine is required to make the turbine work efficiently in this process. In this paper, based on the single nozzle governing method, the effect of the variation of the full circumferential relative stator installation angle on the system performance improvement under the rated output work condition is investigated. It is shown that the specific work of the variable relative stator installation angle can be improved by up to 6.3 % relative to the design stator installation angle and up to 15.7 % relative to the throttle governing method under the base pressure of 10.0 MPa. With the same absence of throttling losses, the specific work of 3-nozzle inlets method is higher than that of 4-nozzle inlets method, and the turbine internal losses are reduced by 10.6 %. This study provides a theoretical basis for the design, optimization and operation control of nozzle governing turbines.
Optimized design of smart toilet spray bar flow channel based on CFD
Authors: Zhou Qiwei , Zhu Chenbing , Chen Jianchong , Yang Xuelong 
Published: March 2024

Abstract
Currently, there are significant issues with the intelligent toilets available on the market, such as a large swing of the spray bar when spraying water column and eccentricity. This paper presents four optimization schemes for the intelligent toilet spray bar channel by analysing and redesigning a specific model. Computational Fluid Dynamics (CFD) technology was employed to analyse the water flow conditions inside the spray bar of the intelligent toilet. The calculation results indicate that for the same water inlet flow rate, the optimal structure in optimization scheme 1 is the block with a length (L) of 1.5 mm. In optimization scheme 2, the optimal structure is the block located at position (3). In optimization scheme 3, the optimal structure is a 15° rotation, which exhibits the least swirls and pressure loss while maintaining the prototype structure. When the prototype structure is modified, the optimal structure in optimization scheme 4 is the excision bend pipe. This structure exhibits the lowest swirl number and pressure loss among all the optimization schemes. The determined structure offers valuable insights for enhancing the flow characteristics of the improved product.
Numerical erosion prediction of aluminum induced by cavitating jet using an Eulerian–Lagrangian method
Authors: Wang Zhengdong , Li Linmin , Li Xiaojun , Zhu Zuchao 
Published: March 2024

Abstract
Cavitation-induced erosion in pump machinery is a significant issue that leads to material loss and increased operating costs. This study develops a numerical method based on an energy balance approach to address the risk of cavitation erosion. Compared with other published methods, three improvements are made. Firstly, it assumes that the local instantaneous pressure is the driving force behind cavity collapse, rather than the far-away ambient pressure field. Secondly, it counts erosion only at the moment that the released shock wave is strong enough to cause surface damage. Thirdly, an Eulerian–Lagrangian method is introduced to simulate multiscale cavitation, in which the volume of fluid (VOF) method and a discrete bubble model (DBM) are combined to reproduce resolvable water-vapor interfaces and unresolvable discrete bubbles, respectively. The developed numerical modeling framework is validated by predicting the erosion of pure aluminum surface caused by a cavitating jet, and it is shown that the simulated erosion region fits well against the experimental results. Additionally, appropriate model coefficients of the erosion prediction method are introduced to achieve quantitative prediction of material mass loss, and the detailed erosion behavior is discussed.
Simulation analysis of bubble coalescence behavior characteristics in non-Newtonian fluids based on the phase field method
Authors: Long Li 
Published: March 2024

Abstract
Gas-liquid two-phase flow is widely used in various fields of chemical production because of its stability. The bubble coalescence behavior has a significant impact on the size, shape and movement of bubbles. These parameters are important parameters for affecting the interphase mass and heat transfer processes and equipment performance. This paper presents a simulation study of the bubble coalescence behavior of non-Newtonian fluids using the phase field method through simulation software. The relative location of bubbles were divided into three types: vertical, parallel and random; and also the distribution of bubbles can be divided into three cases: symmetric, left-skewed and right-skewed. This paper focuses on the influence of the arrangements of the bubbles on their coalescence behavior in non-Newtonian fluids. The results show that in non-Newtonian fluids, the relative distance of the bubbles and the flow characteristics of the fluid are both key factors in whether bubble coalescence can occur, and they exhibit different patterns of action when the bubbles are in different arrangements. Also bubbles show different patterns of motion in different distributions.