bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study on cavitation performance improvement of high-power centrifugal pump impeller
Authors: Zheng Yang , Meng Long , Wang Xin , Xue Peng , Zhang Chiye , Tian Yajuan 
Published: March 2024

Abstract
High power centrifugal pump is frequently used in large project for water resources allocation. Cavitation phenomenon causes noise and vibration and affects the centrifugal pump unit stability. The impeller model was used an initial impeller to be developed, and the impeller geometry, the blade profile, blade inlet edge were optimized by design method based on numerical simulation technique to improve cavitation performances. The 3D model with the initial and optimized impeller were simulated to obtain cavitation characteristic. The results of optimization impeller are compared and verified by model test. The numerical simulation results show that the pressure distribution is distributed on the blade surface is uniform and the location of lowest pressure is reasonable. The test results show that the optimized design significantly increases the ratio of plant cavitation coefficient σp to incipient cavitation coefficient σi and critical cavitation coefficient σ1 of the impeller under normal operation conditions, the safety margin of cavitation is increased. It was confirmed from numerical simulation and model test results that the impeller blade optimization is a reasonable and effective method for cavitation performance improvement. The study results provides design reference for the cavitation performance improvement and safe operation of high power centrifugal pump.
Numerical investigation of vortex structure and unsteady evolution in multi-stage double-suction centrifugal pump
Authors: Zhao Jiantao , Pei Ji , Yuan Jianping , Wang Wenjie 
Published: March 2024

Abstract
Multi-stage double-suction centrifugal pump is constructed to handle situations with large flow rates and high head. However, due to the complex internal flow structure, the pump can experience hydraulic excitation caused by the presence of numerous vortical structures. Such excitation can lead to unstable pump operation and increased energy losses. In this study, we aim to analyze the multi-stage double-suction centrifugal pump by combining numerical simulation using detached eddy simulation (DES) and experiments to accurately capture the vortical structure and elucidate the mechanism of the rotor-stator interaction (RSI) formation. The results indicate that the omega vortex identification method can accurately capture the vortex structure in the pump, irrespective of the threshold value and without the influence of wall shear layers. Additionally, based on this identification method, we have analyzed the unsteady evolution characteristics of the vortex structure in the pump. Specifically, we have focused on the shedding of wake vortices and their collision with the tongue. The findings suggest that the rotor-stator interaction primarily arises from the periodic shedding of wake vortices near the impeller outlet. In summary, this study provides valuable insights into the flow dynamics of multi-stage turbomachines.
Comparative study on stator corner separation vortex characteristics in axial-flow pump and tubular pump: To understand the effects of guide-vane cone diffusion on horn-like vortices
Authors: Wang B H , Wang F J , Wang C Y , Wang H , Yao Z F , Xiao R F 
Published: March 2024

Abstract
The guide-vane cone diffusion is a typical structural difference between an axial-flow pump and a tubular pump, which is shown as low diffusivity and high diffusivity respectively, but it is still unclear how this structural difference affects the vortex characteristics in stator corner separation flows. In this paper, a comparative study of stator corner separation flows in an axial-flow pump and a tubular pump was conducted, and the effects of guide-vane cone diffusion on vortical structures were clarified. Firstly, for the apparent vortical features, compared with the guide-vane of axial-flow pump with low diffusivity, the horn-like vortex in the guide-vane of tubular pump with high diffusivity has the features of smaller scale, weaker swirling strength, shorter evolution cycle and lower pressure fluctuations. Secondly, for the vortex dynamics mechanism, the guide-vane cone diffusion of tubular pump can cause additional pressure energy recovery, which leads to higher adverse pressure gradients, so it is easier to induce additional shroud backflow near the suction surface. In this coupled flow field of main flow, namely hub corner separation flow and shroud backflow, the streamwise periodic oscillation of the pressure function gradient
ωS

·▽(▽p/ρ) is found, and it induces the unique vortex-street-like distributions of the deformational vorticity
ωS

and the rigid vorticity
ωR

. This physical effect causes a mutual competition between the horn-like vortex near the hub corner and the opposite backflow vortex near the shroud side. It is this competition effect originating from the guide-vane cone diffusion that greatly suppresses the development of the horn-like vortex in a tubular pump.
A numerical study on the unsteady flow in the guide vane of a water-jet propulsion mixed-flow pump
Authors: Sun C , Wang L Y , Dai Y X 
Published: March 2024

Abstract
Mixing and dissipation of the complex vortices in the water-jet propulsion mixed-flow pump is an important source of flow loss. Furthermore, some vortices have strong unstable feature, which adversely affect vibration and noise. The unsteady flow in the guide vane of a mixed-flow pump is studied by numerical methods. Through the spectral results of hydrodynamic excitation and the instantaneous flow field of the mix-flow pump, the basic unsteady features of the unsteady flow are obtained. Peak frequency of approximately 1.68 rotation frequency is found as the dominant frequency of the excitation in the guide vane. Dynamic mode decomposition (DMD) is then used to extract the key flow modes in the guide vane. The results illustrate the dominant flow structure in the guide vane, including upstream sweeping structures, the separate vortex structures, and large-scale passage vortex structure. The upstream sweeping wake caused the fluctuation in the boundary layer and induced flow separation. Following the separation, passage vortices are induced which has the dominant frequency 1.68 rotation frequency.
Study on the experiment and numerical simulation of cavitation flow mechanisms at different flow rates in water-jet propulsion pumps
Authors: Kaixuan Zheng , Yun Long , Qingjiang Xiang , Changjian Xu , Jianping Chen , Dezhong Wang 
Published: March 2024

Abstract
Cavitation is an important factor causing vibration and noise of water-jet pump. High-performance ships require water-jet pumps with high efficiency and low noise at high speeds. At present, the cavitation flow phenomenon and interference mechanism of the water-jet pump under different flow rates are not clear enough. This paper takes the mixed-flow water jet propulsion pump as the research object. The flow structure of the cavitation vortex of the water-jet pump under different flow rates was obtained by high-speed photography (HSP). Through comparison of numerical simulation and test results, the cavitation performance curves and cavitation flow structures of the water jet pump under five different flow rates were obtained. The influence of cavitation vortex structure on the performance of water-jet pump under different flow rates was obtained. The correlation between cavitation performance and cavitation vortex structure under different flow rates was established. This research work will help to understand the impact of the cavitation vortex structure of the water-jet pump under different flow rates and capture the evolution law of the cavitation vortex structure of the water-jet pump under different flow rates. And provide reference for improving the cavitation performance of water-jet pumps.
Hydraulic structure optimization of centrifugal pump based on orthogonal test
Authors: Li Wei , Pu Wei , Ji Leilei , Zhang Xing , He Xinrui 
Published: March 2024

Abstract
To reduce global carbon emissions and reduce the energy consumption of pumps, it is necessary to continuously improve the performance efficiency of pumps. In this paper, the blade wrapping angle, inlet mounting angle and outlet mounting angle are selected as the design variables, and the hydraulic structure of the pump is orthogonally optimized. Through experiments and simulations, the internal flow bonding and external energy characteristics of the centrifugal pump under different orthogonal test combinations were compared, and finally the impeller wrapping angle was 130 degrees, the outlet installation angle was 20 degrees, and the inlet installation angle was 40 degrees. It is found that compared with the original design scheme, the efficiency of the optimized scheme under the design flow rate is increased by 2.775%, and the hydraulic loss in the impeller is reduced by 1.18%. The main and secondary orders of influence of parameter factors on lift and efficiency are impeller wrapping angle, impeller outlet mounting angle, and impeller inlet mounting angle. The internal flow of the optimized impeller is significantly improved, and the flow loss is reduced. The research results provide a design basis for further improving the hydraulic performance of centrifugal pumps.
Effect of different blade number and thickness on performance of micro-turbine
Authors: Chen Jianchong , Zhou Qiwei , Zhu Chenbing , Yang Xuelong 
Published: March 2024

Abstract
At present, due to its special operating environment and operating conditions, there are few relevant theoretical studies and numerical simulation studies on micro-turbines. Therefore, the use of simulation technology to explore the internal flow law of micro-turbines is of great significance for the design optimization guidance of micro-turbines. The research method of this paper is through CFD software, using SST k-ω algorithm model. This paper studies the efficiency and output of micro-turbine with 8 blade numbers of 13,15,17,19,21,23,25 and 28, as well as the efficiency and output of micro-turbine with thickness of 12mm, 12.5mm, 13mm, 13.5mm and 14mm. The internal flow field characteristics, the pressure pulsation characteristics of impeller region and tip clearance region and the power loss distribution diagram are studied and analyzed. The results show that the maximum efficiency is 22.42% when the number of blades is 15, and 23.92% when the thickness is 10.5mm.
Study on the energy conversion characteristics in the impeller of ultra-low specific speed pump as turbine
Authors: He Jiawei , Si Qiaorui , Wang Peng , Wan Bochen , Wang Chenguang 
Published: March 2024

Abstract
With the increasing attention to micro-hydropower generation, pump as turbine (PAT) has broad prospects in the field of micro-hydropower generation due to low price and easy maintenance. The ultra-low specific speed has the advantage of large output power under a small flow rate and is widely used in remote areas to realize micro-hydropower generation. In this paper, With the goal of maximizing the output power at a small flow rate, an ultra-low specific speed pump as turbine (USSPAT) of 16.52 is designed. The energy characteristics inside the impeller are studied by means of experimental and simulation. It is found that the main output area in the impeller located in the inlet area of impeller and near Span0.6 area. In addition, it is found that the high-speed jet caused by RSI inside the impeller and the secondary circulation at the outlet area are the main flow structures that hinder the work of the impeller.
Aerodynamic modeling of ducted fans under environmental disturbances
Authors: Luo Yiwei , He Yuhang , Qian Yuping , Zhang Yangjun 
Published: March 2024

Abstract
Ducted fans are widely used in unmanned aerial vehicles (UAVs) to perform various tasks due to high efficiency, high safety and low noise. The external environment affects the stability of the ducted fan, and predicting the aerodynamic characteristics under environmental disturbances is of great significance for stable operations of ducted-fan aircraft. In this paper, we considered the influence of different environmental disturbances on the axial velocity through the rotor disk, and established an aerodynamic mechanism model based on the momentum theory and blade element theory. In order to verify the model validity, three-dimensional CFD (Computational Fluid Dynamics) numerical simulation and bench tests were carried out. The results indicate that the mechanism model can well predict the thrusts and torques of the ducted fan under different flow conditions and wall constraints, and the errors between the model and the simulation results are generally within 12%. Overall, the established model is universal and extendable for different types of disturbances, and has the potential to be applied to evaluate the impact of unknown disturbances.
Experimental investigation on coupling characteristics of principal and shear stress of wind turbine under dynamic change of wind direction
Authors: Yan Sijia , Wang Jianwen , Zhang Jianwei , Gao Zhiying , Bai Yefei 
Published: March 2024

Abstract
The wind direction misalignment problem significantly impacts the abnormal alteration in aerodynamic distribution, ultimately resulting in an abnormal stress response of wind turbines. In this study, an experimental method was employed to simulate dynamic wind changes. The study aimed to analyze the laws and mechanisms governing changes in principal and shear stress on wind turbine blades and towers under different wind dynamic change angles. The results revealed that variations in the initial tip speed ratio significantly influenced the stress experienced by the tower during dynamic changes in wind direction. The coupling effect of yaw and gyroscopic moments led to a transient increase in both principal and shear stresses in the wind turbine tower during the early stage of wind direction change. Due to inertia and aerodynamic deterioration, the principal and shear stress values of wind turbine blades and towers exhibited delayed changes. Notably, when the wind direction changed by 15° from the direction the turbine was facing, the principal stress fluctuations in the wind turbine tower and blade were 5.13 and 1.23 times higher, respectively. Therefore, when developing a small-angle yaw strategy, stress fluctuations should be comprehensively considered, in addition to power requirements.
Analysis of internal flow characteristics of water-jet propulsion under turning conditions
Authors: Chen Jiahao , Pan Zhongyong , Wu Xu 
Published: March 2024

Abstract
In order to explore the internal flow characteristics of the water-jet propulsion under turning conditions, we carried out numerical simulations of the axial-flow water-jet propulsion under different turning conditions and set up monitoring points at the inlet and outlet of the impeller to analyse the internal pressure pulsation law of the water-jet propulsion under different turning conditions. The calculation results show that the propulsion performance of the propeller decreases with the increase of the turning angle, and the left turn is better than the right turn. The vortices mainly appear around the rotor shaft, the inlet of the suction pipe and the side wall opposite to the suction pipe. The larger the turning angle, the larger the vortex area in the impeller section, while in right-hand rotation, the vortex on the suction surface decreases and the vortex on the trailing edge increases. The opposite is true for left-hand rotation. The change in pressure on the inlet surface of the impeller with the rotation angle is less pronounced compared to right-hand rotation. In addition, the pressure pulsation pattern on the impeller outlet surface is slightly improved in left-hand rotation compared to right-hand rotation.
Numerical simulation of the complex flow field in a new recycling cyclone separator
Authors: Liu Q X , Li Z L , He X J 
Published: March 2024

Abstract
The three-dimension flow field is simulated in a recycling cyclone separator using the Reynolds stress model (RSM) with Fluent 6.2. The results show that the unique design of the flow route of the recycling cyclone separator can improve the axial symmetry and the order of the inner flow field. The appearance of the eddy flow and the pressure drop of the recycling cyclone separator are also reduced. Moreover, the secondary circulation in the recycling cyclone separator is analyzed, which is useful for understanding the flow mechanism. This study provides a reference for further improvement of the recycling cyclone separator.
Heavy-duty gas turbine 3D blade modelling and flow field analysis
Authors: He Zongze , Xin Jiali , Guan Jin , Weng Yiwu , Lv Xiaojing 
Published: March 2024

Abstract
Hydrogen-fuelled heavy-duty gas turbine is an important trend of gas turbine due to its low emission characteristics. Due to the change of components and thermodynamic properties of the fuel, the physical properties of the working fluid of the turbine will change and affect the performance of the gas turbine. In this study, through 3D scanning and inverse modelling, the parametric models of the turbine blades were obtained. CFD analysis was conducted to analyse the change of thermodynamic performance and flow field under different fuel, which is natural gas, 50% natural gas and 50% hydrogen and hydrogen. The result of the CFD indicated that the efficiency of natural gas fuelled working flux is 92.86%, and decreased by 0.19% and 0.83% with hydrogen doped in. It is analysed that though the increased magnitude of relative velocity with hydrogen doped in, the increased flow attack angle of the rotor, from -4.74°, to -3,61°, to -1.88° with hydrogen doped in, caused the split of rotor leading edge cooling air and decreased the efficiency of the turbine stage. Modification of blade metal angle could boost the efficiency of the turbine stage under hydrogen-doped fuel.
Impact of uncertainty in the physics-informed neural network on pressure prediction for water hammer in pressurized pipelines
Authors: Huang Hai , Guo Pengcheng , Yan Jianguo , Zhang Bo , Mao Zhenkai 
Published: March 2024

Abstract
In pressurized pipeline systems, accurate prediction of water hammer pressure is crucial for ensuring safe system operation. When the boundary conditions are unknown and measured data is sparse, both traditional methods fully based on physical equations and data-driven neural network methods have difficulty in accurately predicting water hammer pressure. The physics-informed neural network (PINN) overcomes these challenges by simultaneously incorporating measured data and physical equations during the network training process. However, PINN has uncertainties and their impact on the accuracy of pressure prediction is not yet clear. In this study, the valve closing water hammer in a reservoir-pipeline-valve system is taken as the research object, we investigate the influence of the uncertainty of physics and data in the PINN on prediction accuracy by using water hammer equations with various friction models and training data with various noise levels. The results show that using the water hammer equation with the Brunone model, the PINN model has higher prediction accuracy. Furthermore, data noise levels less than 10% have a relatively small impact on pressure prediction accuracy, indicating that the PINN model has good robustness in terms of data noise levels.
Numerical analysis of accelerating and decelerating ducts modified by camber on the unsteady flow field of pump-jet
Authors: Zhou Yunkai , Yuan Jianping , Fu Yanxia , Gao Quanlin 
Published: March 2024

Abstract
Utilizing the Reynolds-averaged Navier-Stokes equations method in conjunction with Detached Eddy Simulation model, this paper investigates effects of duct camber (f) on transient hydrodynamic characteristics, particularly propulsion performance and flow field behavior. The research begins by validating the numerical methodology through experimental and numerical assessments of propeller VP1304 and a pump-jet operating under mooring conditions. The exploration commences with examining propulsion characteristics, followed by analyzing time-domain and frequency-domain data, wherein thrust fluctuations and pulsating pressures are scrutinized via fast Fourier transform (FFT). The pressure distribution and velocity field are subsequently presented to unveil the mechanisms triggered by variations in f. Comparative findings highlight that in cases of pump-jets with lower camber, the outlet velocity exceeds the inlet velocity, a trend contrary to scenarios involving higher f values. Additionally, by analyzing vorticity magnitude distribution and vortices, this study attains comparative insights into the effects of accelerating and decelerating ducts on rotor and stator trailing vortices, offering a window into the flow instability mechanism amidst diverse duct configurations. The results showcased to demonstrate the substantial impact of f variation on hydrodynamic properties. This comprehensive investigation yields practical guidance for the optimal design of pump-jets, potentially informing future design endeavours.
Investigation on influence mechanism of length-to-diameter ratio on fluid-structure interaction characteristic of serpentine nozzle
Authors: Li Qiulin , Zhou Li , Shi Jingwei , Zhang Yi , Wang Zhanxue 
Published: March 2024

Abstract
The effect of different length-to-diameter ratios on the fluid-structure coupling characteristics of double serpentine nozzle for turbofan engine was studied by using serial bidirectional loose coupling method. The results show that the structural deformation of the serpentine nozzle is mainly located at the downstream channel of the first bend of the nozzle and the upper wall of the exit of the nozzle, and with the increase of the length-to-diameter ratio, the deformation amount of the nozzle gradually increases. The maximum deformation of the upper and lower walls of the serpentine nozzle occurs in the downstream region of the first bend of the serpentine nozzle. The fluid-structure coupling effect has an influence on the flow field characteristics and aerodynamic performance of the serpentine nozzle. When the length-to-diameter ratio is 2.4, the influence of fluid-structure coupling effect is lowest, and the total pressure recovery coefficient decreases by 0.40%, the flow coefficient decreases by 5.34%, and the thrust coefficient decreases by 0.92%. When the length-to-diameter ratio is 3, the influence of fluid-structure coupling effect is highest, and at this time, the total pressure recovery coefficient decreases by 0.48%, the flow coefficient decreases by 5.95%, and the thrust coefficient decreases by 1.12%.
A numerical investigation of using vortex generators to improve a flush waterjet performance
Authors: Du X , Zhou Y Y , Chen L , Dai R 
Published: March 2024

Abstract
The flow separation on the ramp side of the inlet duct is the main reason for the performance degradation of the waterjet propulsion system under low inlet velocity ratio (IVR) conditions. A micro ramp vortex generator (MRVG) is installed on the bottom of the ship before the inlet entrance to suppress the ramp flow separation and to reduce the inlet flow distortion and improve the efficiency of the waterjet propulsion pump. The influences of the vortex generator on the overall performance and internal flow fields are computed with CFD solver. The results show that under the IVR=0.5 condition, the MRVG device can suppress the flow separation on the ramp side of the inlet duct. It increases the uniformity coefficient of the inlet flow from 0.64 to 0.75, but decreases the total pressure recovery coefficient by 0.02. The total pressure distortion DC60 is reduced by 0.665. After the installation of the vortex generator, the thrust of the propulsion system is increased by 4.01%, and the propulsion efficiency is improved by 3.99%.