Research of the Influence of Single-Flow and Dual-Flow Patterns on Fuel Tank Washing Inerting Process

Wenyi Liu,Xuefei Huang,Weihua Liu 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.2

The purpose of this study is that safety issues of modern aircraft always attract extensive attention worldwide. The combustion and explosion of fuel tank system is one of the main causes of aircraft accident. This paper builds a general mathematical model for a multi-compartment fuel tank and provides the initial conditions for a solution using the Runge–Kutta method according to mass conservation, the equation of nitrogen–oxygen dissolution and evolution, and the equation of gas flowing through the orifice. Nitrogen-enriched air (NEA) flow is usually used to decrease the oxygen concentration inside fuel tank to keep it below the oxygen concentration required to support combustion. With a four-compartment fuel tank as the research objective and adopting a domestic separation membrane to generate NEA, single-flow and dual-flow patterns are designed, respectively. Also, a washing inerting simulation is performed and the variation in the average oxygen concentration in the fuel tank and each compartment with the flight envelope is analyzed. The research results indicate that these two patterns can both meet the requirement that the average oxygen concentration of the upper ullage in the fuel tank should be lower than 12%. Although the single-flow pattern is simpler than the dual-flow pattern, it cannot avoid external air entering the fuel tank, which will cause the oxygen concentration in some compartments to be higher than 12% during the diving phase, while the dual-flow pattern can guarantee that the oxygen concentration of compartments does not exceed the limits during the entire flight. With the comparison between single-flow and dual-flow patterns, this study may provide some reference for the further design and study of washing inerting process for fuel inerting system.

Developing Brønsted–Lewis acids bifunctionalized ionic liquids based heteropolyacid hybrid as high-efficient solid acids in esterification and biomass conversion

Yong Liu,Yuefeng Wu,Miaojun Su,Weihua Liu,Xiying Li,Fujian Liu 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

A class of Brønsted–Lewis acid bifunctionalized ionic liquids based heteropolyacid hybrid (BLA-ILs-HPA)solid acids were developed by combining the double sulfonic groups grafted, ionic liquids basedheteropolyacid hybrid with Lewis acidic centers (M = Zn, Co, Fe, Ni, Cu). The prepared BLA-ILs-HPA showboth Brønsted and Lewis acidic sites with extremely-high acid strength and enhanced stabilities, asdetermined by FT-IR, Py-IR, TG, XPS and 31P solid state NMR results. BLA-ILs-HPA were successfullyapplied in esterification camphene with acetic acid to produce isobornyl acetate, and dehydration ofglucose to produce 5-hydrozymethylfural. BLA-ILs-HPA show enhanced catalytic activities in comparisonwith various acid catalysts. The effects of reaction temperatures, initial reactant molar ratio, catalystdosage, and reaction time were studied in detail. The optimal reaction conditions were obtained, and theexperimental data was successfully correlated by a pseudohomogeneous (PH) reaction kinetic model inthe temperature range of 313.15–333.15 K. The calculated values obtained by the reaction kinetic modelwere in good agreement with the experimental data. Moreover, as a heterogeneous reaction catalyst,BLA-ILs-HPA can be recovered by simple treatment. After six times cycling, the decreasing in the catalyticactivity of BLA-ILs-HPA could not be observed significantly, suggesting their good reusability.

Black rice anthocyanidins prevent retinal photochemical damage via involvement of the AP-1/NF-κB/Caspase-1 pathway in Sprague-Dawley Rats

Hao Jia,Wei Chen,Xiuhua Wu,Shuai Li,Hong Liu,Jiru Liao,Weihua Liu,Mantian Mi,Longjian Liu,Daomei Cheng,Xiaoping Yu 대한수의학회 2013 Journal of Veterinary Science Vol.14 No.3

The effects of black rice anthocyanidins (BRACs) on retinal damage induced by photochemical stress are not well known. In the present study, Sprague-Dawley rats were fed AIN-93M for 1 week, after which 80 rats were randomly divided into two groups and treated with (n = 40) or without BRACs (n =40) for 15 days, respectively. After treatment, both groups were exposed to fluorescent light (3,000 ± 200 lux; 25oC), and the protective effect of dietary BRACs were evaluated afterwards. Our results showed that dietary BRACs effectively prevented retinal photochemical damage and inhibited the retinal cells apoptosis induced by fluorescent light (p < 0.05). Moreover, dietary BRACs inhibited expression of AP-1 (c-fos/c-jun subunits), up-regulated NF-κB (p65) expression and phosphorylation of IκB-α, and decreased Caspase-1 expression (p < 0.05). These results suggest that BRACs improve retinal damage produced by photochemical stress in rats via AP-1/NF-κB/Caspase-1apoptotic mechanisms.

Three dimensional numerical simulations for non-breaking solitary wave interacting with a group of slender vertical cylinders

Weihua Mo,Philip L.-F. Liu 대한조선학회 2009 International Journal of Naval Architecture and Oc Vol.1 No.1

In this paper we validate a numerical model for-structure interaction by comparing numerical results with laboratory data. The numerical model is based on the Navier-Stokes(N-S) equations for an incompressible fluid. The N-S equations are solved by two-step projection finite volume scheme and the free surface displacements are tracked by the slender vertical piles. Numerical results are compared with the laboratory data and very good agreement is observed for the time history of free surface displacement, fluid particle velocity and force. The agreement for dynamic pressure on the cylinder is less satisfactory, which is primarily caused by instrument errors.

Design of a type of broadband metamaterial absorber based on metal and graphene

Liu Wen,Tian Jinping,Yang Rongcao,Pei Weihua 한국물리학회 2021 Current Applied Physics Vol.31 No.-

In this paper, we demonstrate a kind of broadband metamaterial perfect absorber using both graphene and metal resonator elements. Through step by step design and simulation, wider absorption band from about 4.22 THz to 7.48 THz with average absorption rate up to 98.21% is achieved in the absorption spectrum. In addition, the absorber has characteristics of polarization insensitivity and wide incident angle due to its inherent rotational symmetry. Moreover, the absorption band can be adjusted by changing the chemical potential of the graphene. The superiorities of broadband, high absorption rate, polarization independent and wide-angle characteristics make it have potential application prospects in electromagnetic wave absorbing, signal sensing and detection, and other optoelectronic devices.

An investigation on the cooling characteristics of impingement-reversed convection film cooling in a curved section

Weihua Yang,Xiangli Li,Xue Liu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.5

An experiment was designed at the curving section of a combustion chamber to study the effects of cooling effectiveness on impingement-reversed convection film cooling with and without pin fins. Numerical simulations were also carried out. The effectiveness of compound cooling increased with the rise in blowing ratio. With regard to the effect of the pin fins, impingement pin fin-reversed convectionfilm cooling was more effective than the method without pin fins, particularly for smaller blowing ratio conditions. The number and arrangement of fin pin rows had a small effect on cooling efficiency under the same blowing ratio value. Simulation results agreed well with experimental data and could be used to optimize basic design.

Investigation of synergistic adsorption between methyl orange and Cd(II) from binary mixtures on magnesium hydroxide modified clinoptilolite

Weihua Zou,Lie Liu,Hongping Li,Xiuli Han 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.7

The simultaneous removal of Methyl orange (MO) and Cd2+ (mainly from organo-metallic dyes) onto magnesium hydroxide modified clinoptilolite (MHMC) was described and compared to a single adsorbate situation. The adsorption performance was studied by batch experiments. The adsorption mechanism of MO and Cd2+ on MHMC was investigated. Langmuir and Dubinin-Raduskevich (D-R) isotherm successfully predicted the adsorption of MO and Cd2+ in single and binary systems. Maximum adsorption capacity calculated from Langmuir isotherm equation in single solution for MO and Cd2+ was 0.305 and 0.282mmol/g, respectively. In a binary system of MO/Cd2+, the adsorption capacity for both MO and Cd2+ was higher than in single solutions. The results indicated that the adsorption system of MO/Cd2+ presented a synergistic effect, not competitive adsorption, which suggested that MHMC can be used as an adsorbent for removal of dyes and heavy metal in the multi-solute system.

Investigation of an STATCOM-based Energy Stored Quasi-Z Source Cascaded H-bridgeInverter Photovoltaic Power System

Weihua Liang,Yitao Liu,Shiqi Jiang,Jianchun Peng,Hui Jiang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The energy stored quasi-Z source cascaded Hbridge (ES-qZS-CHB) inverter is widely used in photovoltaic (PV) power generation system because of its unique advantages. However, the existing researches on ESqZS-CHB inverter PV power system mainly focus on the transmission of active power, but pay little attention to reactive power, causing the ES-qZS-CHB inverter PV power system cannot compensate reactive power or improve system performance. This paper proposes a PV power generation and static synchronous compensator based ESqZS-CHB inverter system, to implement the PV generation and reactive power compensation at the same time. Simulation and experimental results verify the system’s excellent performance.

Bias process for heteroepitaxial diamond nucleation on Ir substrates

Wang Weihua,Yang Shilin,Liu Benjian,Hao Xiaobin,Han Jiecai,Dai Bing,Zhu Jiaqi 한국탄소학회 2023 Carbon Letters Vol.33 No.2

Heteroepitaxy is a better method of enlarging SCD wafer size than homoepitaxy. In this work, several aspects of the bias process for heteroepitaxial diamond nucleation are studied experimentally. First, with increasing bias time, the diamond-nucleation pathway is found to transform from “isolated-crystal nucleation” to “typical domain-nucleation” and back to “isolated-crystal nucleation.” An interdependent relationship between bias voltage and bias time is proposed: the higher the bias voltage, the shorter the bias time. Second, a correlation exists between the threshold bias voltage and reactor-chamber pressure: a higher reactor chamber pressure usually requires a higher threshold bias voltage to realize “typical domain nucleation.” Third, diamond bias-enhanced nucleation and growth is observed at a high CH4 content, where the dynamic equilibrium between amorphous-carbon-layer deposition and atomic-hydrogen etching is broken. Finally, epitaxial nucleation is obtained on a substrate with ∅30 mm in a home-made MPCVD setup.

Stimulating or Suppressing - The Effects of Different Types of Instruction on Rated Creativity

Jenny Liu,Weihua Niu,Debora Day 대한사고개발학회 2010 The International Journal of Creativity & Problem Vol.20 No.2

A total of 128 high school sophomores in two different academic levels participated in a study to examine the effect of different instructions on rated creativity. In each level, students were randomly assigned into one of three groups and were given instructions emphasizing no special focus, positive encouragement, or pressured encouragement, to use in completing two creativity tasks in the art and literature domains. It was hypothesized that both positive and pressured encourage-ment instructions would promote students’ creativity. It was also hypothesized that students with relatively higher academic preparation (level 1) would benefit more from the positive encouragement instruction, whereas students with relatively lower academic preparation (level 2) would benefit more from the pressured encouragement instruction. A 2 (domain of creativity: art and literature) X 3 (ways of instruction: no-focus, positive encouragement, and pressured encouragement) X 2 (gender: female and male) X 2 (academic level: level 1 vs. level 2) factorial mixed design ANCOVA was used to analyze the data to test the above two hypothesis. Results in both domains of this study supported the two hypotheses. In addition, results also indicated that girls’ average creativity is negatively affected by pressured encouragement instruction while boys’ is not. Findings from this research will assist in future studies exploring promoting individuals’ creativity in high school.