Experiment and modeling of liquid-phase flow in a venturi tube using stereoscopic PIV

Song, Yuchen,Shentu, Yunqi,Qian, Yalan,Yin, Junlian,Wang, Dezhong Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.1

Venturi tube is based on turbulent flow, whereby the microbubbles can be generated by the turbulent fragmentation. This phenomenon is common in several venturi bubblers used by the nuclear, aerospace and chemical industries. The first objective of this paper is to study the liquid-phase velocity field experimentally and develop correlations for the turbulent quantities. The second objective is to research velocity field characteristics theoretically. Stereoscopic PIV measurements for the velocity field have been analyzed and utilized to develop the turbulent kinetic energy in the venturi tube. The tracking properties of the tracer particles have been verified enough for us to analyze the turbulence field. The turbulence kinetic energy has a bimodal distribution trend. Also, the results of turbulence intensity along the horizontal direction is gradually uniform along the downstream. Both the mean velocity and the fluctuation velocity are proportional to the Reynolds number. Besides, the distribution trend of the mean velocity and the velocity fluctuation can be determined by the geometric parameters of the venturi tube. An analytical function model for the flow field has been developed to obtain the approximate analytical solutions. Good agreement is observed between the model predictions and experimental data.

Ultimate behaviour and rotation capacity of stainless steel end-plate connections

Yuchen Song,Brian Uy,Dongxu Li,Jia Wang 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.4

This paper presents a combined experimental and numerical study on stainless steel end-plate connections, with an emphasis placed on their ultimate behaviour and rotation capacity. In the experimental phase, six connection specimens made of austenitic and lean duplex stainless steels are tested under monotonic loads. The tests are specifically designed to examine the close-to-failure behaviour of the connections at large deformations. It is observed that the rotation capacity is closely related to fractures of the stainless steel bolts and end-plates. In the numerical phase, an advanced finite element model suitable for fracture simulation is developed. The incorporated constitutive and fracture models are calibrated based on the material tests of stainless steel bolts and plates. The developed finite element model exhibits a satisfactory accuracy in predicting the close-to-failure behaviour of the tested connections. Finally, the moment resistance and rotation capacity of stainless steel end-plate connections are assessed based on the experimental tests and numerical analyses.

Numerical analysis of stainless steel-concrete composite beam-to-column joints with bolted flush endplates

Yuchen Song,Brian Uy,Jia Wang 국제구조공학회 2019 Steel and Composite Structures, An International J Vol.33 No.1

A number of desirable characteristics concerning excellent durability, aesthetics, recyclability, high ductility and fire resistance have made stainless steel a preferred option in engineering practice. However, the relatively high initial cost has greatly restricted the application of stainless steel as a major structural material in general construction. This drawback can be partially overcome by introducing composite stainless steel-concrete structures, which provides a cost-efficient and sustainable solution for future stainless steel construction. This paper presents a preliminary numerical study on stainless steel-concrete composite beam-to-column joints with bolted flush endplates. In order to ensure a consistent corrosion resistance within the whole structural system, all structural steel components were designed with austenitic stainless steel, including beams, columns, endplates, bolts, reinforcing bars and shear connectors. A finite element model was developed using ABAQUS software for composite beam-to-column joints under monotonic and symmetric hogging moments, while validation was performed based on independent test results. A parametric study was subsequently conducted to investigate the effects of several critical factors on the behaviour of composite stainless steel joints. Finally, comparisons were made between the numerical results and the predictions by current design codes regarding the plastic moment capacity and the rotational stiffness of the joints. It was concluded that the present codes of practice generally overestimate the rotational stiffness and underestimate the plastic moment resistance of stainless steel-concrete composite joints.

Tailoring ZSM-5 zeolite through metal incorporation: Toward enhanced light olefins production via catalytic cracking: A minireview

Yuchen Sha,Lei Han,Ruoyu Wang,Peng Wang,Haitao Song 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.126 No.-

The steam cracking of hydrocarbons has been the major process for light olefins production in recent decades. Recent studies have shown that a considerable amount of propylene and ethylene can be producedby hydrocarbon cracking on modified ZSM-5 zeolite. Various modified elements and post-treatmentmethods have been employed to fulfil the improvement of the catalytic performance over ZSM-5 zeolite. This article focuses on the research progress about the catalytic cracking of hydrocarbons over metalincorporatedZSM-5 zeolite. The mechanism of propylene and ethylene production via catalytic crackingof various hydrocarbons over ZSM-5 zeolite is summarized and the influences of different metal species,such as alkaline earth and alkali metal elements, rare earth metal elements, transition metals, etc. on bothactivity and stability are also discussed. Moreover, the synergistic influence of bimetallic components ismentioned as well. In particular, the effects of different synthetic methods and structures of metal speciesare discussed. We hope that this review will kindle the future rational design of metal-incorporated zeolitecatalysts to realize efficient catalytic cracking of hydrocarbons for light olefins production.

Research on the inlet preswirl effect of clearance flow in canned motor reactor coolant pump

Xu Rui,Song Yuchen,Gu Xiyao,Lin Bin,Wang Dezhong 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.7

For a pressurized water reactor power plant, the reactor coolant pump (RCP) is a kernel component. And for a canned motor RCP, the rotor system's properties determines its safety. The liquid coolant inside the canned motor RCP fills clearance between the metal shields of rotor and stator, forming a lengthy clearance flow. The influence of inlet preswirl on rotordynamic coefficients of clearance flow in canned motor RCP and their effects on the rotordynamic characteristics of the pump are numerically and experimentally investigated in this work. A quasi-steady state computational fluid dynamics (CFD) method has been used to investigate the influence of inlet preswirl. A vertical experiment rig has also been established for this purpose. Rotordynamic coefficients on different inlet preswirl ratios (IR) are obtained through CFD and experiment. Results show that the cross-coupled stiffness of the clearance flow would change significantly with inlet preswirl, but other rotordynamic coefficients would not change significantly with inlet preswirl. For the case of clearance flow between the stator and rotor cans, influence of inlet preswirl is not so significant as the IR is not large enough.

Progressive collapse analysis of stainless steel composite frames with beam-to-column endplate connections

Jia Wang,Brian Uy,Yuchen Song,Dongxu Li 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.36 No.4

This paper carries out the progressive collapse analysis of stainless steel composite beam-to-column joint sub-models and moment-resisting frames under column removal scenarios. The static flexural response of composite joint sub-models with damaged columns was initially explored via finite element methods, which was validated by independent experimental results and discussed in terms of moment-rotation relationships, plastic hinge behaviour and catenary actions. Simplified finite element methods were then proposed and applied to the frame analysis which aimed to elaborate the progressive collapse response at the frame level. Nonlinear static and dynamic analysis were employed to evaluate the dynamic increase factor (DIF) for stainless steel composite frames. The results suggest that the catenary action effect plays an important role in preventing the damaged structure from dramatic collapse. The beam-to-column joints could be critical components that influence the capacity of composite frames and dominate the determination of dynamic increase factor. The current design guidance is non-conservative to provide proper DIF for stainless steel composite frames, and thus new DIF curves are expected to be proposed.

Numerical Study and Design Recommendations of Eccentrically Loaded Partially Encased Composite Columns

Hai Wang,Jie Li,Yuchen Song 한국강구조학회 2019 International Journal of Steel Structures Vol.19 No.3

A numerical investigation is presented in this paper on partially encased composite (PEC) columns subjected to eccentric loading. 3D fi nite element (FE) models were established based on the dynamic explicit method, which were validated by comparing the FE outcomes with some available test results in previous literature. Using the verifi ed model, a parametric study was conducted to investigate the eff ects of several factors on the strength and behaviors of PEC columns, including the concrete strength, the steel yield strength, and the load eccentricity. The outcomes of the FE analyses, together with the test results reported in previous studies, were compared with the capacities predicted by the current design codes for eccentrically loaded PEC columns. It was found that the existing design methods with the assumption of rectangular stress blocks (fully plastic assumption) could be unconservative in some circumstances. Therefore, a modifi ed partially plastic design approach was proposed based on the Eurocode 4 design method, which was confi rmed to be conservative yet economic in predicting the interactive force–moment (N–M) capacity of PEC columns under eccentric compression.

Assessment of titanium alloy bolts for structural applications

Dongxu Li,Brian Uy,Jia Wang,Yuchen Song 국제구조공학회 2022 Steel and Composite Structures, An International J Vol.42 No.4

This paper explored the viability of utilising titanium alloy bolts in the construction industry through an experimental programme, where a total of sixty-six titanium alloy (Ti/6Al/4V) bolts were tested under axial tension, pure shear and combined tension and shear. In addition, a series of Charpy V-notch specimens machined from titanium alloy bolts, conventional high-strength steel bolts, austenitic and duplex stainless steel bolts were tested for impact toughness comparisons. The obtained experimental results demonstrated that the axial tensile and pure shear capacities of titanium alloy bolts can be reasonably estimated by the current design standards for steel structures (Eurocode 3, AS 4100 and AISC 360). However, under the combined tension and shear loading conditions, significant underestimation by Eurocode 3 and unsafe predictions through AS 4100 and AISC 360 indicate that proper modifications are necessary to facilitate the safe and economic use of titanium alloy bolts. In addition, numerical models were developed to calibrate the fracture parameters of the tested titanium alloy bolts. Furthermore, a design-based selection process of titanium alloy bolts in the structural applications was proposed, in which the ultimate strength, ductility performance and corrosion resistance (including galvanic corrosion) of titanium alloy bolts was mainly considered.

Behaviour and design of Grade 10.9 high-strength bolts under combined actions

Dongxu Li,Brian Uy,Jia Wang,Yuchen Song 국제구조공학회 2020 Steel and Composite Structures, An International J Vol.35 No.3

The use of high-strength steel and concrete in the construction industry has been gaining increasing attention over the past few decades. With it comes the need to utilise high-strength structural bolts to ensure the design load to be transferred safely through joint regions, where the space is limited due to the reduced structural dimensions. However, research on the behaviour of high-strength structural bolts under various loading combinations is still insufficient. Most of the current design specifications concerning high-strength structural bolts were established based on a very limited set of experimental results. Moreover, as experimental programs normally include limited design parameters for investigation, finite element analysis has become one of the effective methods to assist the understanding of the behaviour of structural components. An accurate and simple full-range stress-strain model for high-strength structural bolts under different loading combinations was therefore developed, where the effects of bolt fracture was included. The ultimate strength capacities of various structural bolts obtained from the present experimental program were compared with the existing design provisions. Furthermore, design recommendations concerning the pure shear and tension, as well as combined shear and tension resistance of Grade 10.9 high-strength structural bolts were provided.

Sensorless Control of the Switched Reluctance Motor Based on the Sliding-Mode Observer

Li Xinyu,Liu Jiayu,Ge Lefei,Zhong Jixi,Huang Jiale,Zhao Yuchen,Song Shoujun 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.2

To upgrade the application of switched reluctance motors (SRMs) for more electric aircraft, this paper presents a method with sensorless control based on the flux-linkage data from the finite element method. First, a calibration strategy is employed to obtain the flux-linkage characteristics. Then, a sliding-mode observer is used to realize the sensorless control of the SRM. The proposed method only requires the flux-linkage of the SRM at aligned and unaligned rotor positions from the experiment which takes a low-measurement effort to get the rotor position and has better accuracy in position and speed estimation than the FEM. Experimental results verify the accuracy and effectiveness of the proposed method.