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Theoretical and Experimental Studies for the Transient Response of Cavity

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Journal of Thermal Science 2020年第1期29卷 232-240页

作者： HU Jianping LIU Zhenxia zhu pengfei LYU Yaguo School of Power and Energy Northwestern Polytechnical UniversityXi’an 710129China Shaanxi Key Laboratory of Internal Aerodynamics in Aero-Engine Xi’an 710129China

During the transient state of aero-engine,cavity has evidently transient characteristics in the secondary air *** investigate transient characteristics,theoretical and experimental studies were implemented for both static and rotating *** of all,the typical transient response phenomena in secondary air system were investigated based on the basic concepts of the dynamic *** to the basic theory of gas dynamics,the causes of transient phenomena were analyzed in two aspects,external disturbance,and system physical *** dimensionless parameters were introduced to analyze the transient response characteristics of air ***,the experimental results of the static cavity indicated that the actual response time increased with the increase of the inlet *** experimental results of the rotor-stator cavity showed that the low rotational speed on the response process had little effect,and the response time gradually increased when the speed continued to ***,the test results of multiple components suggested that when the valve was opening the inlet pressure of the static cavity increased quickly and then reached a stable value,but the pressure of the static cavity,stable pressure cavity and rotor-stator chamber rose *** was also obtained the actual response time of them was *** closer the measuring points were to the disturbance source,the shorter the delay time was.

关键词： secondary air system static cavity rotating cavity transient response experiment

Kinetics and mechanism studies on scandium calix[6]arene complex initiating ring-opening polymerization of 2,2-dimethyltrimethylene carbonate

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Science China Chemistry 2007年第5期50卷 648-653页

作者： GOU pengfei zhu WeiPu SHEN ZhiQuan Key Laboratory of Macromolecule Synthesis and Functionalization Ministry of Education Institute of Polymer Science Zhejiang University Hangzhou 310027 China Key Laboratory of Macromolecule Synthesis and Functionalization Ministry of Education Institute of Polymer Science Zhejiang University Hangzhou 310027 China Key Laboratory of Macromolecule Synthesis and Functionalization Ministry of Education Institute of Polymer Science Zhejiang University Hangzhou 310027 China

Scandium p-tert-butylcalix[6]arene complex has been synthesized from scandium isopropoxide and p-tert-butylcalix[6]arene and used as a single component initiator for the first time. The polymerization of 2,2-dimethyltrimethylene carbonate (DTC) using this complex can proceed under mild conditions. Poly (2,2-dimethyltrimethylene carbonate) (PolyDTC) with weight-average molecular weight of 33700 and molecular weight distribution of 1.21 can be prepared. Kinetics study indicates that the polymeri- zation rate is first order with respect to both monomer and initiator concentrations, and the apparent activation energy of the polymerization is 22.7 kJ/mol. 1H NMR spectrum of the polymer reveals that the monomer ring opens via acyl-oxygen bond cleavage leading to an active center of Sc-O.

关键词： ring-opening polymerization, scandium calixarene complex, 2,2-dimethyltrimethylene carbonate (DTC), polycarbonates

Ingenious Design of Co Al-LDH p-n Heterojunction Based on CuI as Holes Receptor for Photocatalytic Hydrogen Evolution

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Chinese Journal of Structural Chemistry 2022年第6期41卷 79-85页

作者： Yue Cao Hongqian Gou pengfei zhu Zhiliang Jin School of Chemistry and Chemical Engineering Key Laboratory for Chemical Engineering and TechnologyState Ethnic Affairs CommissionNingxia Key Laboratory of Solar Chemical Conversion TechnologyNorth Minzu UniversityYinchuan 750021China School of Environmental Science and Engineering Shaanxi University of Science and TechnologyXi’an 710021China

Reasonable design of heterojunction can greatly improve the photocatalytic hydrogen evolution activity of ***,p-n heterojunction of 2D/3D structure is constructed by the nanosheet of CoAl-LDH and rock-like *** introduction of CuI can make CoAl-LDH disperse better,which brings more reaction sites for the hydrogen evolution ***,the 2D/3D structure is conducive to the construction of p-n heterojunction between the CoAl-LDH and *** optical and electrochemical properties of the material indicate that the separation and transference of photon-generated carriers are promoted by the p-n *** activity of composite catalyst(CI-10)reaches a maximum of 3.59 mmol g^(−1) h^(−1) which is 28.5 times higher than that of ***,the influence of the amount of CuI and pH value on the hydrogen evolution reaction is *** on the band structures of CoAl-LDH and CuI,the mechanism of photocatalytic reaction of CI-10 is *** p-n heterojunction constructed with the CuI as hole receptor provides a new way to enhance the activity of photocatalytic H_(2) evolution.

关键词： CoAl-LDH CuI p-n heterojunction photocatalysis hydrogen production

Effects of Sealing Flow Supply Configuration with Holes on Sealing Effectiveness of Turbine Rim Seal

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Journal of Thermal Science 2023年第1期32卷 366-386页

作者： GAI Zepeng zhu pengfei HU Jianping LIU Zhenxia YIN Hang School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China

This paper proposes a new-designed rim seal configuration with sealing holes based on the conventional radial rim seal,and presents a numerical comparison of the sealing performance between the conventional sealing flow supply configuration and the new sealing flow supply configuration with holes at different sealing flow *** sealing effectiveness and unsteady flow yields at the rim seal are numerically simulated by using the URANS method and SST turbulent model from ANSYS *** influence of the new sealing flow supply configuration on the sealing effectiveness at different sealing flow rates is *** effectiveness of different sealing flow rates in the conventional rim seal is also *** to the conventional rim seal,the increase in the sealing flow rate reduces the degree of gas ingestion induced by the effect of mainstream ingress at the rim clearance,while the unsteady flow characteristics are enhanced,and the number and amplitude of the low-frequency signals *** position of the Kelvin-Helmholtz instabilities vortex structures is left by the increased sealing flow rate,and its strength is *** with the conventional rim seal configuration,the new sealing flow supply configuration with holes could reduce the sealing efficiency by 5.06%at most at sealing flow distribution m_(1):m_(2)=3:1 when Cw=2000,and improve the sealing efficiency by 11.71%at most at sealing flow distribution m_(1):m_(2)=1:1 when Cw=*** shows that the lateral jet from the holes induces a larger-scale Kelvin-Helmholtz vortex structure at Cw=2000,thus the sealing efficiency in the wheel space is also ***,the size of the Kelvin-Helmholtz vortex structures is significantly suppressed by the new sealing flow supply configuration at Cw=7500,which is beneficial to improving the sealing effectiveness of the conventional rim seal.

关键词： secondary air system rim seal ingestion and seal unsteady flow discrete sealing holes

Modification of Nano Tourmaline Surface Treatment Agent and Its Performance on Negative Ion Release

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Computers, Materials & Continua 2018年第10期57卷 145-150页

作者： Guorui Huang Zhongkai Cui pengfei zhu Xiaoyun Liu East China University of Science and Technology No.130 Meilong RoadShanghai200237China Department of Chemistry Universitéde MontréalC.P.6128Succ.Centre VilleMontréalQuébecCanadaH3C 3J7

In this paper,a kind of wall fabric’s surface treatment agent modified with nonionic surfactant was *** surface treatment agent was prepared by using nano tourmaline powder dispersion in water with surfactant as dispersants by sand *** the influence of different dispersants,the negative ions releasing amount of functional wall fabrics,the milling process and the storage stability of nano tourmaline powder dispersion were *** results showed that nano tourmaline powder dispersion achieved the smallest average diameter of 44 nm and had best storage stability that the average diameter maintained below 200 nm in 17 days when the addition amount of dispersant was 20 percent of the tourmaline powders’*** is more,the quantity of negative ion releasing achieved 6500 ion/cm3 when addition amount of dispersant was 30 *** technique could be used to strengthen productivity of nano tourmaline powder dispersion.

关键词： Tourmaline dispersant negative ion storage stability wall fabrics

Human-in-the-loop image segmentation and annotation

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Science China(Information Sciences) 2020年第11期63卷 290-292页

作者： Xiaoya ZHANG Lianjie WANG Jin XIE pengfei zhu Department of Computer Science and Engineering Nanjing University of Science and Technology College of Intelligence and Computing Tianjin University

Dear editor,Semantic segmentation aims to assign the category information to all pixels of an image and plays a vital role in image understanding. In the past few years, deep convolutional neural networks have achieve... 详细信息

关键词： Semantic segmentation Active learning Human-machine collaboration Pseudo labelling Image Annotation

Three-Dimensional Numerical Simulation of Ice Crystal Melting in Jet Engine

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Journal of Thermal Science 2019年第5期28卷 984-992页

作者： zhu pengfei ZHANG Jiachen HAN Bingbing ZHANG Lifen LIU Zhenxia School of Power and Energy Northwestern Polytechnical University Xi'an 710129 China Shanghai Aircraft Airworthiness Certification Center of CAAC Shanghai 200335 China

A method was presented for calculating the melting rate of ice crystals in different axial positions in a compressor. The volume of fluid model and enthalpy-porosity model were used to simulate the melting process of single ice crystal. The result was validated by experimental data from literature. The change of the liquid fraction of the ice crystals with the axial position was obtained when the temperature distribution inside the compressor was introduced into the melting process. The liquid fraction of the spherical ice crystals was fitted with the ice crystal diameter as a variable, and the general distribution function for computing liquid fraction in any axial position in the compressor was obtained. The function of axial position as a variable for non-spherical ice crystal was also got.

关键词： ice crystals three-dimensional simulation melting process liquid fraction

Lateral photovoltaic effect in the Ni-SiO_(2)-Si structure with bias

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Optoelectronics Letters 2024年第5期20卷 257-264页

作者： LING Xiang zhu pengfei zhu Kun SONG Pei LI Xiong School of Mathematics Physics and StatisticsShanghai University of Engineering ScienceShanghai 201600China School of Electrical Engineering Liupanshui Normal UniversityLiupanshui 553004China School of Railway Telecommunication Hunan Technical College of Railway High-speedHengyang 421002China

We designed a clamping device to study lateral photovoltaic effect (LPE) in Ni-SiO_(2)-Si structure with bias due to the appropriate barrier *** LPE has a prominent sensitivity and linearity with 532 nm wavelength *** transient response time is 450μs and the relaxation time is 2 250μs in the Ni-SiO_(2)-Si structure without *** LPE sensitivity has a significant improvement with *** transient response time is 6μs and the relaxion time is 47μs with-7 V bias,not only improving the LPE sensitivity,but also increasing the response speed with *** research shows that the Schottky barrier structure can improve the sensitivity and linearity of LPE with bias effectively,and thus it can be used in position sensitive sensors.

关键词： LPE structure effect

High performance CuO-CeO_2 catalysts for selective oxidation of CO in excess hydrogen:Effect of hydrothermal preparation conditions

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Journal of Natural Gas Chemistry 2009年第3期18卷 346-353页

作者： pengfei zhu Jing Li Qinqin Huang Siming Yan Mei Liu Renxian Zhou Institute of Catalysis Zhejiang University Hangzhou 310028 Zhejiang China School of Chemistry and Chemical Engineering Southwest Petroleum University Chengdu 610500 Sichuan China

High performance CuO-CeO2 catalysts for selective oxidation of CO in excess hydrogen were prepared by a hydrothermal method under different preparation conditions and evaluated for catalytic activities and selectivities. By changing the ^nCTAB/^nCe ratio and hydrothermal aging time, the catalytic activity of the CuO-CeO2 catalysts increased and the operating temperature window, in which the CO conversion was higher than 99%, was widened. XRD results showed no peaks of CuOx species and Cu-Ce-O solid solution were observed. On the other hand, Cu＋ species in the CuO-CeO2 catalysts, which was associated with a strong interaction between copper oxide clusters and cerium oxide and could be favorable for improving the selective oxidation performance of CO in excess H2, were detected by H2-TPR and XPS techniques.

关键词： selective oxidation CO excess hydrogen CuO-CeO2 catalyst hydrothermal preparation condition