scholarly journals Crosswise Wind Shear Represented as a Ramped Velocity Profile Impacting a Forward-Moving Aircraft

2019 ◽  
Vol 2019 ◽  
pp. 1-18
Author(s):  
Mahmood Khalid
Keyword(s):  
Wind Shear ◽  
Large Scale ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Vortical Flow ◽  
Atmospheric Conditions ◽  
Wing Model ◽  
Lateral Plane ◽  
Wind Velocities ◽  
3D Wing

Abrupt changes in wind velocities over small distances in a lateral or vertical direction can produce wind shear which is known to have serious effects upon the performance of an aircraft. Brought about by large-scale changes in the atmospheric conditions, it is a three-dimensional flow phenomenon imposing severe velocity gradients on an aircraft from all possible directions. While it would be difficult to model an instantaneous velocity gradient in a lateral plane, a vortical flow impinging from the sides which represents a wind shear in a vertical direction is imposed on a forward-moving aircraft to investigate the effect on the aerodynamic performance. The maximum shear wind speed from the side was fixed at 0.3 times the forward velocity. After due validations under no-wind shear conditions on simpler half-reflection plane models, a BGK airfoil-based full 3D wing and the ONERA M6 3D wing model were selected for preliminary studies. The investigation was concluded using the ARA M100 wing-fuselage model.

scholarly journals Characterization of the vertical evolution of the three-dimensional turbulence for fatigue design of tidal turbines

2020 ◽  
Vol 378 (2178) ◽  
pp. 20190495 ◽  
Author(s):  
Maxime Thiébaut ◽  
Jean-François Filipot ◽  
Christophe Maisondieu ◽  
Guillaume Damblans ◽  
Christian Jochum ◽  
...  
Keyword(s):  
Turbulence Intensity ◽  
Large Scale ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Tidal Energy ◽  
Tidal Turbines ◽  
Tidal Stream ◽  
Vertical Evolution ◽  
Tidal Stream Energy ◽  
Scale Turbulence

A system of two coupled four-beam acoustic Doppler current profilers was used to collect turbulence measurements over a 36-h period at a highly energetic tidal energy site in Alderney Race. This system enables the evaluation of the six components of the Reynolds stress tensor throughout a large proportion of the water column. The present study provides mean vertical profiles of the velocity, the turbulence intensity and the integral lengthscale along the streamwise, spanwise and vertical direction of the tidal current. Based on our results and considering a tidal-stream energy convertor (TEC) aligned with the current main direction, the main elements of turbulence prone to affect the structure (material fatigue) and to alter power generation would likely be: (i) the streamwise turbulence intensity ( I x ), (ii) the shear stress, v ′ w ′ ¯ , (iii) the normal stress, u ′ 2 ¯ and (iv) the vertical integral lengthscale ( L z ). The streamwise turbulence intensity, ( I x ), was found to be higher than that estimated at other tidal energy sites across the world for similar height above bottom. Along the vertical direction, the length ( L z ) of the large-scale turbulence eddies was found to be equivalent to the rotor diameter of the TEC Sabella D10. It is considered that the turbulence metrics presented in this paper will be valuable for TECs designers, helping them optimize their designs as well as improve loading prediction through the lifetime of the machines. This article is part of the theme issue ‘New insights on tidal dynamics and tidal energy harvesting in the Alderney Race’.

PIV Study of Mildly Controlled Flow Over a Wing Model Using a Synthetic Jet Array

2016 ◽  
Author(s):  
Pramod B. Salunkhe ◽  
Hui Tang ◽  
Yanhua Wu
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Separated Flow ◽  
Synthetic Jet ◽  
Particle Image Velocimetry System ◽  
Wing Model ◽  
Subsonic Wind Tunnel ◽  
Discrete Structures ◽  
Controlled Flow ◽  
Pod Analysis

This work describes the use of a synthetic jet (SJ) array for mild control of flow separation over a straight wing model. Experiments were performed in a subsonic wind tunnel to show improvement of the wing aerodynamic performance. A tomographic particle image velocimetry system was used to measure and analyze the three-dimensional flow-field with and without the SJ actuation. It was observed that, although the SJ array is relatively weak, it can still made impacts on the separated flow. After the SJ actuation, the large-scale vortex structures in the shear layer were broken into small discrete structures and the near-wall flow was substantially improved. Subsequently, Proper Orthogonal Decomposition (POD) analysis was also conducted and the effectiveness of the present SJ array was further discussed.

scholarly journals An account of low level wind shear over Chennai airport - Part II : Turbulence and eddy dissipation

MAUSAM ◽  
2021 ◽  
Vol 60 (3) ◽  
pp. 325-342
Author(s):  
R. SURESH
Keyword(s):  
Wind Shear ◽  
Three Dimensional ◽  
Civil Aviation ◽  
Atmospheric Conditions ◽  
Velocity Data ◽  
Mean Power ◽  
General Belief ◽  
Low Level ◽  
International Civil Aviation Organisation ◽  
Radial Velocity Data

In-flight reports on Low Level Wind Shear (LLWS) received from aircrafts are used to issue wind shear alerts for all subsequent landing aircrafts as per standing guidelines of International Civil Aviation Organisation (ICAO). In this paper, winds reported by aircrafts at 1000 and 1800 ft. are used to validate the wind estimated from DWR measured radial wind data employing standard algorithms. Turbulence indices and parameters have been computed independently using conventional (RS/RW) upper air data, aircraft measured winds and DWR estimated winds and compared these with wind shear induced turbulence reported by aircrews. Mean power law (wind escalation law) profiles in the boundary layer have been arrived at for unstable and stable atmospheric conditions.                   Three dimensional shear (3DS) upto 600 m a.g.l. has been worked out from DWR measured radial velocity data and compared with wind shear computed from RS/RW and aircraft measured winds and DWR estimated winds. It is found that 3DS values of more than 16 * 10-3 s-1 predict well the occurrence of moderate turbulence. Contrary to the general belief that wind shear is a short lived phenomenon which may last for a few minutes only, it has been observed that incidences of LLWS and induced moderate turbulence lasting more than 10 hrs are not at all uncommon over Chennai aircraft.

scholarly journals Solar3D: An Open-Source Tool for Estimating Solar Radiation in Urban Environments

2020 ◽  
Vol 9 (9) ◽  
pp. 524
Author(s):  
Jianming Liang ◽  
Jianhua Gong ◽  
Xiuping Xie ◽  
Jun Sun
Keyword(s):  
Solar Radiation ◽  
Open Source ◽  
Large Scale ◽  
Three Dimensional ◽  
Solar Irradiation ◽  
Slope Aspect ◽  
Atmospheric Conditions ◽  
3D City Models ◽  
Grass Gis ◽  
City Models

Solar3D is an open-source software application designed to interactively calculate solar irradiation on three-dimensional (3D) surfaces in a virtual environment constructed with combinations of 3D-city models, digital elevation models (DEMs), digital surface models (DSMs) and feature layers. The GRASS GIS r.sun solar radiation model computes solar irradiation based on two-dimensional (2D) raster maps for a given day, latitude, surface and atmospheric conditions. With the increasing availability of 3D-city models and demand for solar energy, there is an urgent need for better tools to computes solar radiation directly with 3D-city models. Solar3D extends the GRASS GIS r.sun model from 2D to 3D by feeding the model with input, including surface slope, aspect and time-resolved shading, which is derived directly from the 3D scene using computer graphics techniques. To summarize, Solar3D offers several new features that—as a whole—distinguish this novel approach from existing 3D solar irradiation tools in the following ways. (1) Solar3D can consume massive heterogeneous 3D-city models, including massive 3D-city models such as oblique airborne photogrammetry-based 3D-city models (OAP3Ds or integrated meshes); (2) Solar3D can perform near real-time pointwise calculation for duration from daily to annual; (3) Solar3D can integrate and interactively explore large-scale heterogeneous geospatial data; (4) Solar3D can calculate solar irradiation at arbitrary surface positions including on rooftops, facades and the ground.

scholarly journals Solar3D: A 3D Extension of GRASS GIS r.sun for Estimating Solar Radiation in Urban Environments

2020 ◽  
Author(s):  
Jianming Liang ◽  
Jianhua Gong ◽  
Xiuping Xie ◽  
Jun Sun
Keyword(s):  
Solar Radiation ◽  
Large Scale ◽  
Three Dimensional ◽  
Urban Environments ◽  
Solar Irradiation ◽  
Slope Aspect ◽  
Atmospheric Conditions ◽  
3D City Models ◽  
Grass Gis ◽  
City Models

Solar3D is an open-source software application designed to interactively calculate solar irradiation at three-dimensional (3D) surfaces in a virtual environment constructed with combinations of 3D city models, digital elevation models (DEMs), digital surface models (DSMs) and feature layers. The GRASS GIS r.sun solar radiation model computes solar irradiation based on two-dimensional (2D) raster maps for given day, latitude, surface and atmospheric conditions. With the increasing availability of 3D city models and demand for solar energy, there is an urgent need for better tools to computes solar radiation directly with 3D city models. Solar3D extends GRASS GIS r.sun from 2D to 3D by feeding the model with input, including surface slope, aspect and time-resolved shading, that is derived directly from the 3D scene using computer graphics techniques. To summarize, Solar3D offers several new features which, as a whole, distinguish itself from existing 3D solar irradiation tools: (1) the ability to consume massive heterogeneous 3D city models, including massive 3D city models such as oblique airborne photogrammetry-based 3D city models (OAP3Ds or integrated meshes); (2) the ability to perform near real-time pointwise calculation for duration from daily to annual; (3) the ability to integrate and interactively explore large-scale heterogeneous geospatial data. (4) the ability to calculate solar irradiation at arbitrary surface positions including at rooftops, facades and the ground. Solar3D is publicly available at https://github.com/jian9695/Solar3D.

Particle Image Velocimetry Measurements of the Three-Dimensional Flow in an Exhaust Hood Model of a Low-Pressure Steam Turbine

2006 ◽  
Vol 129 (2) ◽  
pp. 411-419 ◽  
Author(s):  
Wei Zhang ◽  
Bu Geun Paik ◽  
Young Gil Jang ◽  
Sang Joon Lee ◽  
Su Eon Lee ◽  
...  
Keyword(s):  
Flow Structure ◽  
Large Scale ◽  
Particle Image ◽  
Guide Vane ◽  
Three Dimensional ◽  
Vortical Flow ◽  
Exhaust Hood ◽  
Three Dimensional Flow ◽  
Image Velocimetry ◽  
End Wall

The three-dimensional flow structure inside an exhaust hood model of a low-pressure steam turbine was investigated using a particle image velocimetry (PIV) velocity field measurement technique. The PIV measurements were carried out in several selected planes under design operation conditions with simulated total pressure distribution and axial velocity profile. The mean flow fields revealed a complicated vortical flow structure and the major sources of energy loss. Vortices with different scales were observed inside the exhaust hood: a strong separation vortex (SV) behind the tip of the guide vane, a longitudinal vortex (LV) at the exhaust hood top, a large-scale passage vortex (PV) evolving throughout the flow path, and an end-wall vortex (EWV) in the region adjacent to the front end-wall. Both the SV and the large-scale PV seemed to consume large amounts of kinetic energy and reduce the pressure recovery ability. The results indicate that the steam guide vane and the bearing cone should be carefully designed so as to control the vortical flow structure inside the exhaust hood.

Instantaneous three-dimensional vorticity measurements in vortical flow over a delta wing

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1612-1620
Author(s):  
A. Honkan ◽  
J. Andreopoulos
Keyword(s):  
Delta Wing ◽  
Three Dimensional ◽  
Vortical Flow

About the Development of Brick-Design in Russia

2020 ◽  
Vol 787 (12) ◽  
pp. 21-24
Author(s):  
Y.A. Bozhko ◽  
◽  
K.A. Lapunova ◽  
Keyword(s):  
Functional Role ◽  
Three Dimensional ◽  
Vertical Direction ◽  
Basic Unit ◽  
Design Development ◽  
European Cities ◽  
Unique Material ◽  
Decisive Action ◽  
Color Combinations ◽  
Insufficient Number

The article reflects the authors view on the technical and aesthetic side of the use of face bricks in the architecture of our country. The term brick design combines such indicators of brickwork as the color, size and surface of the brick itself, as well as the type of masonry and seam parameters. Unfortunately, the analysis of the current situation shows that the culture of consumption of face bricks in Russia remains at a low level, which is due to the lack of proper knowledge and insufficient number of qualified master masons. The main goal of brick design development is to popularize various types of three-dimensional masonry and reveal the potential of using bricks as a basic unit. The comparison shows the architecture of European cities, which does not differ in the complexity of architectural forms, but has advantages in the form of unusual masonry, color combinations, vertical direction of masonry and other elements of technical aesthetics. The use of bricks in various levels of brick design will allow you to avoid using architectural decoration on the facades of buildings, while preserving its authenticity and individuality. The brick, as a basic unit, is self-sufficient and is able to fulfill not only its functional role, but also its aesthetic one. In this situation, a necessary and decisive action will be competent communication with industry specialists, architects and designers, leading manufacturers and technologists who realize that we have a unique material that does not need additional wrapping when used efficiently.

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