investigation of local statistical characteristics of turbulent wind flow in atmosphere boundary...
TRANSCRIPT
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
INVESTIGATION OF LOCALSTATISTICAL CHARACTERISTICS OF
TURBULENT WIND FLOW IN ATMOSPHERE BOUNDARYLAYER WITH OBSTACLES
Yuriy Nekrasov, Sergey Turbin
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
2
Introduction
Atmospheric, in particular, wind, load on building designs and the objects in many respects are determined by climatic and topographic features of terrain, in which one the concrete object places. In the article the approaches to perfecting a technique of the collecting and data logging about wind flow in near-ground atmospheric boundary layer with reference to definition of actual wind characteristics near obstacles are considered. Some outcomes of turbulent near-ground parameters research of an atmospheric layer obtained by means of a mock-up sample of a specialized system of continuous monitoring meteorological parameters are submitted.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
3
Experimental investigations of local characteristics of wind flow.
Donbas State Academy of Civil Engineering and Architecture. NW direction – forest.SE direction – four storied buildings.During first part of measurements the thermoanemometer placed on a roof of a four-storied building (altitude of 16 meters), at the altitude 4 meters from a level of a roof.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
4
Experimental investigations of local characteristics of wind flow.
Novoazovsk WPS is situated on the hilly place (distance between hills near 1 km) with differences in heights close to 40 meters, has a grass 20-30 cm and lie 3-4 km from see beach. WPS is located on the hill between two comparatively deep shallow gullies. This location provides possibility of realization for different types of wind flow related with it direction.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
5
Topographical map of Nowoasovsk WPS
- points of wind measurements.
N.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
6
Wind measurement devises
-hot-wire anemometer; - wind direction gauge
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
7
Wind measurement devises. Wind-Ice weather station.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
8
Location of wind measurement devises on towers in Novoazovsk WPS
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
9
Probability density distribution: a)=2.78 m/s, =0.39, Lx=1329m;
b)=2.30 m/s, =0.48, Lx=843m; c)
=2.31m/s, =0.55, Lx=570 m; d)
=2.66 m/s, =0,70, Lx=404 m; e)
=1.82m/s, =0.81, Lx=206m; f)=1.91
m/s, =0.90, Lx=175 m.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
10
V- flow velocity, - its average value, v- dimensionless speed, - mean quadratic deviation(rejection), = / a turbulence level of a flow.
The correction was entered in view of symmetry of a normal distribution, and also taking into consideration that fact, that spacing interval from point of intersection of a curve with an ordinate axis up to average value of dimensionless speed is equal 1.
)1(,2
1
2
1 2
2
2
2
2
)1(
2
)(
vVV
eevp
)2(.2
1 2
2
2
2
2
)1(
2
)1(
vv
eevp
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
11
Corrected probability density distribution function:a) =0.55, b) =0.70
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
12
Gusts and their power representation: а) =2.05, =0.75;b) =2.66, =0.70; c) =1.91, ,=0,9
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
13Integral view of wind flows on Novoazovsk WPS field
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
14
• The diagram of signal of hot-wire anemometer. Height – 24 meters. Average velocity for 1 hour = 9,8 m/sec; level of turbulence =16%; root-mean-square of velocity =1,6 m/sec.
• The diagram of signal of hot-wire anemometer. Height – 10 meters. Average velocity for 1 hour = 6,0 m/sec; level of turbulence =29%; root-mean-square of velocity =1,8 m/sec.
parameters of turbulence levels ([13; 32] %) and longitudinal scale of turbulence (Lx[174; 3061] m )
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
15
Energy spectrum of wind velocity on 24 meters height.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
16
The histogram and density function of
wind gusts duration
exp)( 1p
Parameters of Weibull distribution and have a small scatter in a range [1.04; 1.12]; [0.54; 0.61]. Thus invariance of frequency function of gusts wind duration has been displayed related with the point of measurement.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
17
The histogram and density function of non-dimensional maximums of velocity in gusts.
)1(exp)1()(maxmaxmax
1 vvvp
Vmax - velocity average value determined on the time interval;
- velocity average value determined on the time interval
3600V/V
maxmaxv
vmax - non-dimensional maximum of the gust
3600V
Probability density function of gusts wind maximums has absolutely another character. Depending of measurement points with different wind directions the parameters of distribution change in broad limits: α[1.4; 1.8], а β [2.8; 16.8].
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
18
Conclusions:
The outcome investigations of local meteorological characteristics shows that wind flow characteristics are unpredictable.
Wind flow has non-stationary and non-Gauss character. Place of measurement and wind directions have big influence on Weibull distribution for maximum wind velocity.
The experimental methods are more appropriated for wind load estimation for building structures researches.
DONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTUREDONBAS STATE ACADEMY OF CIVIL ENGINEERING AND ARCHITECTURE
19
Thank you for your attention.