Two-Dimensional Simulation of Frost Formation on the NACA0012 Airfoil under Strong Convection by Using the P-VOF Method

2021 ◽  
Author(s):  
Bin Xia ◽  
Xianghua Xu ◽  
Xingang Liang
Keyword(s):  
Flow Separation ◽  
Volume Fraction ◽  
Early Stage ◽  
Simulation Method ◽  
Vof Method ◽  
Two Dimensional ◽  
Frost Formation ◽  
Naca0012 Airfoil ◽  
Strong Convection ◽  
Frost Layer

Abstract A newly developed frosting simulation method, pseudo-VOF (p-VOF) method, has applied to simulate the dynamic frost formation on the NACA0012 airfoil under strong convection. The p-VOF method is a pseudo volume of fraction simulation method of the multiphase flow with phase change. By solving a simplified mass conservation equation explicitly instead of the original volume fraction equations in CFD software, the efficiency and robustness of calculation are greatly improved. This progress makes it possible to predict a long-time frost formation. The p-VOF method was successfully applied to the simulation of dynamic frosting on the two-dimensional NACA0012 airfoil under strong convection conditions with constant frost physical properties. The simulation result shows that the average thickness of the frost layer increases, and the frost bulges and flow separation appear earlier, when the airfoil surface temperature decreases or the air humidity increases. The frost bulges and flow separation appear earlier, when the air velocity is faster, the growth rate of the frost layer at the early stage is greater, but the final frost layer is thinner.

scholarly journals Two-dimensional simulation of frost formation on the NACA0012 airfoil under strong convection by using the p-VOF method

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Bin Xia ◽  
Xianghua Xu ◽  
Xingang Liang
Keyword(s):  
Flow Separation ◽  
Volume Fraction ◽  
Early Stage ◽  
Vof Method ◽  
Two Dimensional ◽  
Airfoil Surface ◽  
Frost Formation ◽  
Naca0012 Airfoil ◽  
Strong Convection ◽  
Frost Layer

AbstractA newly developed frosting simulation method, p-VOF method, is applied to simulate the dynamic frost formation on the NACA0012 airfoil under strong convection. The p-VOF method is a pseudo VOF method of the multiphase flow simulation with phase change. By solving a simplified mass conservation equation explicitly instead of the original volume fraction equations in CFD software, the efficiency and robustness of calculation are greatly improved. This progress makes it possible to predict a long-time frost formation. The p-VOF method was successfully applied to the simulation of dynamic frosting on the two-dimensional NACA0012 airfoil under strong convection conditions with constant frost physical properties. The simulation result shows that the average thickness of the frost layer increases, and the frost bulges and flow separation appear earlier, when the airfoil surface temperature decreases or the air humidity increases. The frost bulges and flow separation appear earlier, when the air velocity is faster, the growth rate of the frost layer at the early stage is greater, but the final frost layer is thinner.

Observations of Early-Stage Frost Formation on a Cold Plate in Atmospheric Air Flow

2003 ◽  
Vol 125 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Chin-Hsiang Cheng ◽  
Keng-Hsien Wu
Keyword(s):  
Growth Rate ◽  
Early Stage ◽  
Air Flow ◽  
Growth Period ◽  
Layer Growth ◽  
Cold Plate ◽  
Frost Formation ◽  
Atmospheric Air ◽  
Frost Layer ◽  
Frost Growth

The present study is conducted to investigate the frost formation on a cold plate in atmospheric air flow by means of experimental and theoretical methods. In order to provide observations for the early stage of the frost growth process, a microscopic image system is used to record the pattern and the thickness of the frost layer per five seconds after the onset of frost formation. In this study, a multiple-step ascending frost growth pattern caused by melting of frost crystals at the frost surface has been observed. Effects of velocity, temperature and relative humidity of air (V,Ta, and ϕ) are studied, and the surface temperature of the cold plate Tw is also varied. The considered ranges of these dominant variables are: 2⩽V⩽13 m/s, 20⩽Ta⩽35°C, 40 percent ⩽ϕ⩽80 percent, and −13⩽Tw⩽−2°C. The theoretical model presented by Cheng and Cheng [22] for predicting the frost growth rate during the frost layer growth period is verified. Results show that the predictions of frost growth rate by the model agree with the experiment data, especially for the frost layer growth period.

Instrumentation For Quantitative Microscopy

1977 ◽  
Vol 35 ◽  
pp. 206-209
Author(s):  
B. Ralph ◽  
A.R. Jones
Keyword(s):  
Volume Fraction ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Automatic Data ◽  
Phase Volume Fraction ◽  
Statistical Confidence ◽  
Resultant Data ◽  
Automatic Data Collection ◽  
Third Dimension ◽  
Evolution Of Microstructure

In all fields of microscopy there is an increasing interest in the quantification of microstructure. This interest may stem from a desire to establish quality control parameters or may have a more fundamental requirement involving the derivation of parameters which partially or completely define the three dimensional nature of the microstructure. This latter categorey of study may arise from an interest in the evolution of microstructure or from a desire to generate detailed property/microstructure relationships. In the more fundamental studies some convolution of two-dimensional data into the third dimension (stereological analysis) will be necessary.In some cases the two-dimensional data may be acquired relatively easily without recourse to automatic data collection and further, it may prove possible to perform the data reduction and analysis relatively easily. In such cases the only recourse to machines may well be in establishing the statistical confidence of the resultant data. Such relatively straightforward studies tend to result from acquiring data on the whole assemblage of features making up the microstructure. In this field data mode, when parameters such as phase volume fraction, mean size etc. are sought, the main case for resorting to automation is in order to perform repetitive analyses since each analysis is relatively easily performed.

Visual and Theoretical Analyses of the Early Stage of Frost Formation on Cold Surfaces

2007 ◽  
Vol 14 (3) ◽  
pp. 257-268 ◽  
Author(s):  
Xiaomin Wu ◽  
WanTian Dai ◽  
XiaoFeng Shan ◽  
Weicheng Wang ◽  
LiMing Tang
Keyword(s):  
Early Stage ◽  
Frost Formation ◽  
Theoretical Analyses

Free vibration analysis of three-layer thin cylindrical shell with variable thickness two-dimensional FGM middle layer under arbitrary boundary conditions

2021 ◽  
pp. 109963622110204
Author(s):  
Xue-Yang Miao ◽  
Chao-Feng Li ◽  
Yu-Lin Jiang ◽  
Zi-Xuan Zhang
Keyword(s):  
Cylindrical Shell ◽  
Boundary Conditions ◽  
Volume Fraction ◽  
Ritz Method ◽  
Admissible Function ◽  
Free Vibration Analysis ◽  
Middle Layer ◽  
Two Dimensional ◽  
Arbitrary Boundary ◽  
Arbitrary Boundary Conditions

In this paper, a unified method is developed to analyze free vibrations of the three-layer functionally graded cylindrical shell with non-uniform thickness. The middle layer is composed of two-dimensional functionally gradient materials (2D-FGMs), whose thickness is set as a function of smooth continuity. Four sets of artificial springs are assigned at the ends of the shells to satisfy the arbitrary boundary conditions. The Sanders’ shell theory is used to obtain the strain and curvature-displacement relations. Furthermore, the Chebyshev polynomials are selected as the admissible function to improve computational efficiency, and the equation of motion is derived by the Rayleigh–Ritz method. The effects of spring stiffness, volume fraction indexes, configuration on of shell, and the change in thickness of the middle layer on the modal characteristics of the new structural shell are also analyzed.

ACHIEVING REALISTIC TOW FIBER VOLUME FRACTIONS IN TEXTILE COMPOSITE MODELS BY INDUCING FIBER ENTANGLEMENT

2021 ◽  
Author(s):  
GEORGE BARLOW ◽  
MATHEW SCHEY ◽  
SCOTT STAPLETON
Keyword(s):  
Process Simulation ◽  
Manufacturing Process ◽  
Fiber Bundle ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Simulation Method ◽  
Textile Composite ◽  
Compression Pressure ◽  
Fiber Volume ◽  
Composite Models

Modeling composites can be an effective way to understand how a part will perform without requiring the destruction of costly specimens. By combining artificial fiber entanglement with manufacturing process simulation, a method was developed to create fiber bundle models using entanglement to control the fiber volume fraction. This fiber entanglement generation uses three parameters, probability of swapping (p_(r_S )), swapping radius standard deviation (r_(σ_S )), and the swapping plane spacing (l_S), to control the amount of entanglement within the fiber bundle. A parametric study was conducted and found that the more entanglement within a fiber bundle, the more compression mold pressure required to compact the fiber bundle to the same fiber volume fraction as that required for a less entangled bundle. This artificial fiber entanglement and manufacturing process simulation method for creating fiber bundles shows the potential to be able to create bundles with controlled final volume fraction using a desired mold compression pressure.

Frost Formation and its Density Behavior on Various Surfaces

2001 ◽  
Author(s):  
Cheolhwan Kim ◽  
Jongmin Shin ◽  
Alexei V. Tikhonov ◽  
Samchul Ha ◽  
Bongjun Choi
Keyword(s):  
Surface Energy ◽  
Dynamic Contact ◽  
Contact Angles ◽  
Test Time ◽  
Test Results ◽  
Plate Temperature ◽  
Specific Test ◽  
Frost Formation ◽  
Frost Layer ◽  
Density Behavior

Abstract An experimental study has been conducted to investigate the effects of surface energy on frost formation. Test samples with three different surfaces of which Dynamic Contact Angles (DCA) are 23, 55 and 88 degrees are installed in a wind tunnel and exposed to a humid airflow. The thickness and the mass of frost layer are measured and used to calculate frost density while frost formation is visualized simultaneously with their measurements. Results show that frost density increases as time increases at specific test conditions. The air Reynolds number, the airflow humidity and the cold plate temperature are maintained at 12,000, 0.0042 kg/kg and −20 degrees Celsius, respectively. The surface with a lower DCA shows a higher frost density for a two-hour test, but no differences in frost density have been found after two hours of frost generation. Empirical correlations for thickness, mass and density are proposed as the functions of test time and surface energy. Visualization of frost generation was in good agreements with test results.

Effect of Fullerene Volume Fraction on Two-Dimensional Crystal-Constructed Supramolecular Liquid Crystals

2018 ◽  
Vol 14 (1) ◽  
pp. 125-129 ◽  
Author(s):  
Peng Shen ◽  
Xiaoyan Zhang ◽  
Huanjun Lu ◽  
Zebin Su ◽  
Yi Zhou ◽  
...  
Keyword(s):  
Liquid Crystals ◽  
Volume Fraction ◽  
Two Dimensional ◽  
Dimensional Crystal

scholarly journals Carbon Redistribution and Microstructural Evolution Study during Two-Stage Quenching and Partitioning Process of High-Strength Steels by Modeling

Materials ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2302 ◽  
Author(s):  
Yilin Wang ◽  
Huicheng Geng ◽  
Bin Zhu ◽  
Zijian Wang ◽  
Yisheng Zhang
Keyword(s):  
Retained Austenite ◽  
Volume Fraction ◽  
High Strength Steels ◽  
High Strength ◽  
Simulation Method ◽  
Low Carbon ◽  
Two Stage ◽  
Quenching And Partitioning ◽  
Carbon Redistribution ◽  
Carbon Martensite

The application of the quenching and partitioning (Q-P) process on advanced high-strength steels improves part ductility significantly with little decrease in strength. Moreover, the mechanical properties of high-strength steels can be further enhanced by the stepping-quenching-partitioning (S-Q-P) process. In this study, a two-stage quenching and partitioning (two-stage Q-P) process originating from the S-Q-P process of an advanced high-strength steel 30CrMnSi2Nb was analyzed by the simulation method, which consisted of two quenching processes and two partitioning processes. The carbon redistribution, interface migration, and phase transition during the two-stage Q-P process were investigated with different temperatures and partitioning times. The final microstructure of the material formed after the two-stage Q-P process was studied, as well as the volume fraction of the retained austenite. The simulation results indicate that a special microstructure can be obtained by appropriate parameters of the two-stage Q-P process. A mixed microstructure, characterized by alternating distribution of low carbon martensite laths, small-sized low-carbon martensite plates, retained austenite and high-carbon martensite plates, can be obtained. In addition, a peak value of the volume fraction of the stable retained austenite after the final quenching is obtained with proper partitioning time.

scholarly journals DFT Study on Adsorption of Volatile Organic Compounds on Silicene

10.29007/bcpg ◽  
2020 ◽  
Author(s):  
Trong Lam Pham ◽  
Van On Vo ◽  
Van An Dinh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Potential Energy Surfaces ◽  
Early Stage ◽  
Volume Ratio ◽  
Simulation Method ◽  
Early Diagnosis Of Cancer ◽  
Volatile Organic ◽  
Energy Surfaces ◽  
New Sensors

Cancer can be regarded as a rising threat to modern societies. Detecting cancer at an early stage significantly improves the durability of the disease; unfortunately, currently available methods for early diagnosis of cancer are scarce and inefficient. In fact, the concentration of Volatile Organic Compounds (VOCs) in cancer patients in the breath is different from that in normal people. Therefore, the development of new sensors that can detect VOCs with low concentrations at the early stage of cancer, is desirable. 2D materials are expected as attractive materials for these sensors due to their large surface area to volume ratio. In this work, we investigated the adsorption mechanism of some small-to-medium VOCs on the surface of silicene by the quantum simulation method. The images of the potential energy surfaces for different positions of the adsorbate on the silicene surface were explored by Computational DFT-based Nanoscope for the determination of the most stable configurations and diffusion possibilities. The adsorption energy profiles were calculated by three approximations of van der Waals interaction: revPBE-vdW, optPBE-vdW, and vdW-DF2. It is found that the adsorption energies of the VOCs in question vary in the range of 0.6-1.0 eV, which indicates that silicene is considerably sensitive with these VOCs. The charge transfer between the substrate and VOCs was also addressed.

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