STUDY ON THE EFFECT OF VISCOSITY AND COMPRESSIBILITY ON ICE ACCRETION

2009 ◽  
Vol 23 (03) ◽  
pp. 481-484 ◽  
Author(s):  
CHENGXIANG ZHU ◽  
CHUNLING ZHU ◽  
BIN FU
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Fluid Viscosity ◽  
Ice Accretion ◽  
Governing Equations ◽  
Different Parts

Ice accretion on aircraft is studied by a numerical method. By solving governing equations, the flow field is obtained for analyzing the icing zone and calculating the ice quantity on different parts. Influence of the fluid viscosity and compressibility on icing characters is extensively studied. And it can be found that the results agree well with those calculated by LEWICE program. This achievement could be helpful to further research on ice accretion.

3D ICE ACCRETION SIMULATION FOR COMPLEX CONFIGURATION BASING ON IMPROVED MESSINGER MODEL

2012 ◽  
Vol 19 ◽  
pp. 341-350 ◽  
Author(s):  
CHENGXIANG ZHU ◽  
BIN FU ◽  
ZHIGUO SUN ◽  
CHUNLING ZHU
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Turbulence Model ◽  
Calculated Result ◽  
Complex Configuration ◽  
Ice Accretion ◽  
Improved Method ◽  
Experiment Data ◽  
Distribution Scheme ◽  
Good Agreement

Ice accretion on 3D complex configuration is studied by numerical method. The flow field is obtained by using Fluent 6.0 with S-A turbulence model, droplet trajectories and impingement characteristics are obtained using the Eulerian approach, ice shape is calculated basing on the improved Messinger model with a new runback distribution scheme. Using the method presented in this paper, ice accretion on NACA0012 is computed, and the results are in good agreement with the available experiment data. It shows preliminarily that the improved method described in this paper is feasible. Meanwhile, ice accretion on a four-element airplane is studied. According to the analysis of the calculated result, it illustrates that using the method presented in the paper can correctly simulate the ice accretion on 3D complex configuration.

scholarly journals Influence of a Standing Wave Flow-Field on the Dynamics of a Spray Diffusion Flame

Fluids ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 27
Author(s):  
J. Barry Greenberg ◽  
David Katoshevski
Keyword(s):  
Liquid Phase ◽  
Flow Field ◽  
Standing Wave ◽  
Diffusion Flame ◽  
Stokes Number ◽  
Flame Height ◽  
Wave Flow ◽  
Two Dimensional ◽  
Governing Equations ◽  
First Time

A theoretical investigation of the influence of a standing wave flow-field on the dynamics of a laminar two-dimensional spray diffusion flame is presented for the first time. The mathematical analysis permits mild slip between the droplets and their host surroundings. For the liquid phase, the use of a small Stokes number as the perturbation parameater enables a solution of the governing equations to be developed. Influence of the standing wave flow-field on droplet grouping is described by a specially constructed modification of the vaporization Damkohler number. Instantaneous flame front shapes are found via a solution for the usual Schwab–Zeldovitch parameter. Numerical results obtained from the analytical solution uncover the strong bearing that droplet grouping, induced by the standing wave flow-field, can have on flame height, shape, and type (over- or under-ventilated) and on the existence of multiple flame fronts.

Vortex Simulation of Rotor/Stator Interaction in Turbomachinery

1998 ◽  
Author(s):  
Xian Hong Wu ◽  
Mao Zhang Chen
Keyword(s):  
Numerical Methods ◽  
Flow Field ◽  
Diffusion Process ◽  
Numerical Method ◽  
Outer Region ◽  
Vortex Method ◽  
Convective Process ◽  
Rotor Stator Interaction ◽  
Initial Description ◽  
Lagrangian Frame

A new numerical method is presented in this paper to simulate rotor/stator interaction in turbomachinery by use of a vortex method based on a Lagrangian frame. The algorithm takes the result from steady solution as input, which can give an initial description of the unsteady disturbance flow field. To calculate the unsteady response to these disturbances, the Lagrangian vortex method is used to capture the convective process, and the deterministic vortex scheme to approximate the viscous diffusion process. The application of Baldwin-Lomax turbulence model in wakes is developed, so as to overcome the difficulties such as the much higher calculated viscosity in the outer region than that in the boundary regions, and the difficulty in continuously tracing moving wake centerlines encounted by other numerical methods. The agreement between the computational and experimental results is generally good. The sweeping characteristic of wakes, the influence of unsteadiness on incidence and the decaying features of unsteady velocities, pressure are included in the paper.

Numerical Investigation of a Fiber Web Effect on the Pressure Drop and Particles Collection in a Microchannel

2009 ◽  
Author(s):  
Alireza Dastan ◽  
Omid Abouali
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Numerical Investigation ◽  
Particle Motion ◽  
Particle Deposition ◽  
Hydraulic Diameter ◽  
Lagrangian Approach ◽  
Computational Domain ◽  
Governing Equations ◽  
Eulerian Approach

In this paper pressure drop and particle deposition in a microchannel with a hydraulic diameter of 225 micrometer is investigated numerically. Several hundred micron length fibers caught at the entrance of the channels making a “fiber web” also is modeled in this research. Governing equations for the flow field are solved with an Eulerian approach while the equations of particle motion in the flow are solved by a Lagrangian approach. Assuming the symmetry in the domain, one channel and the corresponding plenum are studied in the computational domain. For studying the effects of fibers in the flow, two fiber webs with four and six solid fibers are studied. The increase of pressure drop in the microchannel because of the entrance fiber web is computed and discussed. Also deposition and collection of the particles with various diameters at the fiber webs are also presented.

Integrated Microcomputer-LDV Instrumentation for Studying Finite Wing Aerodynamics

1993 ◽  
Author(s):  
Abdollah Khodadoust
Keyword(s):  
Reynolds Number ◽  
Flow Field ◽  
Data Acquisition ◽  
Fiber Optic ◽  
Three Dimensional ◽  
Laser Doppler ◽  
Laser Doppler Velocimeter ◽  
Ice Accretion ◽  
Wing Model ◽  
Finite Wing

Abstract The effect of a simulated glaze ice accretion on the flow field of a three-dimensional wing is studied experimentally. A PC-based data acquisition and reduction system was used with a four-beam two-color fiber-optic laser Doppler velocimeter (LDV) to map the flow field along three spanwise cuts on the model. Results of the LDV measurements on the upper surface of the finite wing model without the simulated glaze ice accretion are presented for α = 0 degrees at Reynolds number of 1.5 million. Measurements on the centerline of the clean model compared favorably with theory.

scholarly journals Visualization Techniques of Differentially Heated Lid-Driven Square Cavity

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Vekamulla Narayana
Keyword(s):  
Flow Field ◽  
Boundary Conditions ◽  
Computational Cost ◽  
Field Synergy ◽  
Governing Equations ◽  
Square Cavity ◽  
Field Synergy Principle ◽  
Visualization Techniques

In the present study, an attempt is made to explore the flow field inside the differentially heated lid-driven square cavity. The governing equations along with boundary conditions are solved numerically. The simulated results (100 ≤ Re ≤ 1000 and 0.001 ≤ Ri ≤ 10) are validated with previous results in the literature. The convection differencing schemes, namely, UPWIND, QUICK, SUPERBEE, and SFCD, are discussed and are used to simulate the flow using the MPI code. It is observed that the computational cost for all the differencing schemes get reduced tremendously when the MPI code is implemented. Plots demonstrate the influences of Re and Ri in terms of the contours of the fluid streamlines, isotherms, energy streamlines, and field synergy principle.

Modeling and dynamic response of double-feed induction generator and back-to-back converters in unbalanced grid voltage conditions

2019 ◽  
Vol 44 (4) ◽  
pp. 361-372 ◽  
Author(s):  
Ali Mirzakhani ◽  
Reza Ghandehari ◽  
S Alireza Davari
Keyword(s):  
Reference Frame ◽  
Power Plants ◽  
Governing Equations ◽  
Grid Voltage ◽  
Induction Generators ◽  
Wind Power Plants ◽  
Synchronous Reference Frame ◽  
Grid Side ◽  
Unbalanced Grid ◽  
Different Parts

Double-feed induction generators are one of the most commonly used generators in wind power plants. Therefore, studying this type of generators in different grid conditions such as unbalanced grid voltage is of great importance. In this article, double-feed induction generators, in synchronous reference frame, and back-to-back converters are reviewed and modeled. The advantage of this model, compared with previous ones, is that it can be used in unbalanced grid voltage conditions. Hence, different parts of the generator in synchronous positive reference frame are studied and governing equations in such conditions are analyzed. Stator output power, rotor side converters, grid side converters, and electromagnetic torque, mentioned in the model, are analyzed, as well. The model is also applied in balanced conditions. Therefore, the model proposed in this article is perfect for analyzing wind turbine-based power plants with double-feed induction generators. The accuracy of the suggested function was confirmed through simulation.

Comparison of Numerical and Experimental “Conical” Flow Fields in Supersonic Corners with Compression and/or Expansion

1977 ◽  
Vol 28 (4) ◽  
pp. 293-306 ◽  
Author(s):  
D A Anderson ◽  
R K Nangia
Keyword(s):  
Flow Field ◽  
Numerical Method ◽  
Three Dimensional ◽  
Solid Surfaces ◽  
Supersonic Stream ◽  
Conical Flow ◽  
Wave Interactions ◽  
Surface Deflection ◽  
Corner Flows ◽  
General Influence

SummaryThe flow field produced by the intersection of two plane solid surfaces in a supersonic stream is a complex interference flow. These flows can be fully compressive, fully expansive or of mixed compression-expansion nature. This paper presents a comparison of the flow field structure in an axial corner obtained experimentally with that predicted numerically by using a shock-capturing finite-difference method. The effect of sweep and surface deflection are evaluated and the general influence of each is presented for the three classes of corner flows. The results of this study show that the numerical method is a valuable aid in understanding the flow structure for simple configurations. In addition confidence in the numerical method is gained for use in solving the more general three-dimensional configurations where the flow is non-conical and several wave interactions may be present.

Numerical Simulation of Impacts of Different Types of Air Duct Outlets on Ventilation Efficiency

2013 ◽  
Vol 438-439 ◽  
pp. 1098-1103
Author(s):  
Chun Zi Nan ◽  
Ji Ming Ma ◽  
Luo Zhao
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Velocity Distribution ◽  
Flow Velocity ◽  
Numerical Method ◽  
Concentration Effect ◽  
Mixing Zone ◽  
Mixing Effect ◽  
Ventilation Efficiency ◽  
Different Types

To enhance the exhaust efficiency during ventilation, three types of air duct outlets were imported. According to the characteristics of velocity distribution simulated by numerical method, the flow field is divided into the mixing zone and the exhaust zone. The gradual contracted air duct outlet can enhance the mixing effect between fresh air and smoke. In the exhaust zone, however, the flow velocity on the upper section of the tunnel is weakened, which is unfavorable for smoke exhaust. Gradual expanded air duct outlet, on the contrary, may weaken the concentration effect of the airflow. The flow velocity on the upper section of the tunnel is increased in the exhaust zone, thus the flow field is more homogenized, which is in favor of smoke exhaust.

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