Structure modification and numerical study of the moisture-separation performance of special crossunder pipe separators for nuclear power steam turbines

Wang Xinjun,Cheng Peng,Xie Jinwei,Zhou Zijie 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.8

The present paper investigated the enhancement of moisture-separation efficiency for ordinary special crossunder pipe separators(SCRUPSs) and proposed three structure-modified separators (combined separator, Z-shaped SCRUPSs, and spiral-type SCRUPSs). Deposition mechanisms for droplets with different sizes were considered using commercial CFD flow solver. Results show that threestructuremodified separators can increase droplet deposition rate to varying degrees. Regarding flow losses, spiral-type SCRUPSs causethe highest increase, with a total pressure loss coefficient of 231%, although it has the best deposition rate improvement. Among the threestructure-modified separators, "Z" shape separator has the best separation performance because of its higher moisture-separation efficiencyand lower total pressure loss efficiency. Results could provide theoretical basis for research on and development of this new typeof moisture separator.

Effects of different constrained boundary structures on the evolution of shock waves and vortexes in muzzle jets

Zijie Li,Hao Wang,Changshun Chen,Hexia Huang 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.10

A gun-track launcher that combines a balanced gun with a rocket track is an important technology for the non-destructive recovery of high-value projectile weapons. Given the restrictions imposed by the track and the interference caused by it, the muzzle jet of such launchers is significantly different from those of traditional artillery. Given this engineering background, this study examines the characteristics of the evolution of supersonic muzzle jets with different constrained boundaries. Results show that the structure of the muzzle jet undergoes a distortion that changes its symmetric circumferential shape into an asymmetric one, tilted above the center of the muzzle. Vortexes are generated below the track owing to lateral airflow, and their formation and evolution lead to significant changes in the pressure of the flow field. Moreover, the asymmetry of the flow field varies owing to the different structures of the side plates of the track, which leads to varying characteristics of the development of shock waves and vortexes in the muzzle jet. The content of this article provides a theoretical basis and necessary technical support for enriching the research connotation and engineering applications of shock wave fields.

Numerical analysis of transient pressure variation in the condenser of a nuclear power station

Xinjun Wang,Zijie Zhou,Zhao Song,Qiankui Lu,Jiafu Li 대한기계학회 2016 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.30 No.2

To research the characteristics of the transient variation of pressure in a nuclear power station condenser under accident condition, a mathematical model was established which simulated the cycling cooling water, heat transfer and pressure in the condenser. The calculation program of transient variation characteristics was established in Fortran language. The pump’s parameter, cooling line’s organization, check valve’s feature and the parameter of siphonic water-collecting well are involved in the cooling water flow’s mathematical model. The initial conditions of control volume are determined by the steady state of the condenser. The transient characteristics of a 1000 MW nuclear power station’s condenser and cooling water system were examined. The results show that at the condition of plant-powersuspension of pump, the cooling water flow rate decreases rapidly and refluxes, then fluctuates to 0. The variation of heat transfer coefficient in the condenser has three stages: at start it decreases sharply, then increases and decreases, and keeps constant in the end. Under three conditions (design, water and summer), the condenser pressure goes up in fluctuation. The time intervals between condenser’s pressure signals under three conditions are about 26.4 s, which can fulfill the requirement for safe operation of nuclear power station.

Excitation of two-colored temporal solitons in a segmented quasi-phase-matching structure

Zeng, Xianglong,Ashihara, Satoshi,Wang, Zijie,Wang, Tingyun,Chen, Yuping,Cha, Myoungsik The Optical Society 2009 Optics express Vol.17 No.19

<P>We conducted a numerical study on the excitation of a two-colored temporal soliton in a segmented quasi-phase-matching (QPM) structure. The device has three parts: a periodic QPM grating for second-harmonic generation, a single domain for phase shift, and a periodic QPM grating for soliton evolution. The second harmonic pulse generated in the first grating works as a seed in the cascaded up-and-down conversions in the second grating. The numerical results showed that the second harmonic seeding enables the excitation of soliton pulses with an improved spatio-temporal intensity profile in a broad bandwidth of the wave-vector mismatch.</P>

AERODYNAMIC CHARACTERISTICS OF MIRA FASTBACK MODEL IN EXPERIMENT AND CFD

Yingchao Zhang,Jintao Zhang,Kaiguang Wu,Zijie Wang,Zhe Zhang 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.4

The lasting high fuel cost has recently inspired the resurgence in drag reduction research for vehicles, which calls for a thorough understanding of the vehicle wake. The acknowledged MIRA fastback vehicle model is characterized by similar real vehicle geometry, thus it is especially suitable for the above purpose. In spite of a considerable number of previous investigations, our knowledge of flow around this model remains incomplete. This paper aims to visit turbulent flow structure behind this model. An investigation has been conducted to measure the near wake flow structure of the MIRA 1/8 scale mode, using both Particle Image Velocimetry (PIV) experimental method and Computational Fluid Dynamics (CFD) simulation method. In order to capture the flow structure accurately, PIV measurement was performed in different sections along three orthogonal directions, and the CFD method acquired additional simulation results to catch the better flow status. Through the maps of the time-averaged vorticity, the instantaneous vorticity and the handled velocity vector from the PIV and CFD methods, we found out the formation mechanism of the transient flow of fastback model and summed up the schematic of flow structure. This study not only analyzed the vortex shedding characteristics of turbulent near wake, but more importantly provided insight into the complex three-dimensional features of the flow structure in the wakes of MIRA fastback model.

Provenance and tectonic setting of the Yimianpo Group in the southeastern Songnen–Zhangguangcai Range Block: constraints on the closure of the Mudanjiang Ocean

Mishan Zhong,Jin Liu,Zhenghong Liu,Jundian Chen,Hongchao Yu,Haipeng Wang,Junshi Lu,Zijie Wu,Mingchen Pan,Liaoning Geological Exploration Institute Co., Ltd.,Yilong Wang 한국지질과학협의회 2023 Geosciences Journal Vol.27 No.4

The timing of the collision between the Songnen–Zhangguangcai Range Block (SNZRB) and the Jiamusi Block (JMSB) is poorly constrained; however, detrital zircons may provide crucial information on the history of this collision. This study focuses on the Yangmugang and Tumenling formations of the Yimianpo Group in the southeastern SNZRB, which were previously thought to have been deposited during the closure of the Mudanjiang Ocean. Detrital zircon U-Pb dating was carried out to constrain the age, provenance, and tectonic setting of the Yangmugang and Tumenling formations, and ultimately the timing of the final closure of the Mudanjiang Ocean. The detrital zircon grains in the two formations yield similar age spectra, with two major age peaks at 275 Ma and 280 Ma, 512 Ma and 525 Ma, respectively. Given the age of the youngest group and that of a granite intrusion, the Yangmugang and Tumenling formations were probably deposited during the middle Permian. The detrital zircon ages also suggest that the Paleozoic igneous rocks distributed across the eastern SNZRB were the major source of the zircons in the formations. Combined with evidence for synchronous arc magmatism, this shows that the Yangmugang and Tumenling formations were likely deposited at a convergent margin and that the collision between the SNZRB and JMSB occurred after the late Permian.