CN103473386A - Method for determining downburst wind profile of horizontal movement - Google Patents

Abstract

The invention provides a method for determining a downburst wind profile of a horizontal movement. The method comprises the following steps of 1, simulating a jet model of a downburst; 2, transforming the jet model into a numerical calculation model; and 3, determining the downburst wind profile of the horizontal movement. By the method, a wind speed computation formula of the downburst is put forward based on the simulation result of the full size computational fluid dynamics (CFD), and a theoretical reference is provided for engineering design. The method is simple in form, thorough in consideration factors, high in precision and efficient in computation.

Description

A kind of method of definite tangential movement downburst wind profile

Technical field

The invention belongs to circuit wind load technical field, be specifically related to a kind of method of definite tangential movement downburst wind profile.

Background technology

Downburst is a kind of high wind that in Thunderstorm Weather, down draft clashes behind ground and forms rapidly.The horizontal wind speed of this high wind increases sharply with highly increasing in zone near the ground, reach peak velocity (peak velocity can reach 70m/s) at less At The Height (20～100m), this has extremely strong destructive power on the buildings that drops on high wind and affect in altitude range as electric power pylon etc.As on June 14th, 2005, downburst caused Siyang, Jiangsu 500kV and has appointed the disposable accident that passes to 10 electric transmission pole towers of 5237 lines; Analysis according to states such as the U.S., Australia and South Africa to the electric transmission pole tower culprit of falling the tower, the electric transmission pole tower accident of falling the tower relevant to weather disaster more than 50% all causes in high wind disasters such as downburst or wind spouts.

In recent years, the impact that worsened by global climate, not only the frequency of occurrences of downburst increases but also its catastrophic effect is also serious all the more, this makes domestic and international scientific research personnel carry on a large amount of research work for the wind field characteristic of downburst, as field observation, test based on scale model and experimental formula research of numerical simulation study and wind profile etc.But engineering design can not be waited for the downburst wind profile result of field observation, and the cycle of test simulation and numerical simulation is long, somewhat expensive, therefore, form is succinct, calculate efficient wind profile experimental formula has obtained the wide application of sending out at engineering design field, and the scientific research personnel is also updating relevant wind profile formula, makes it more approach measured result.

Wind profile experimental formula research in the past almost all concentrates in the matching of rotational symmetry stable state wind profile, and has obtained abundant achievement in research; But downburst has not only comprised the rotational symmetry stable situation, also have equally the downburst of tangential movement, and the wind speed of this downburst on its direction of motion is stronger, more easily cause the destruction of skyscraper as electric power pylon etc.Wind profile research for the motion downburst, only has the people such as Holmes [Holmes, J.D, Oliver, S.E., 2000.An empirical model of a downburst.Engineering Structures, 22,1167-1172] method that downburst translational velocity and the direct linear superposition of stable state wind profile speed are calculated the motion wind profile proposed.But the strong minute linear characteristic because downburst flows, only adopt linear superposition method to carry out the speed stack, can predict mistakenly the wind speed in non-linear wind field.

Summary of the invention

In order to overcome above-mentioned the deficiencies in the prior art, the invention provides a kind of method of definite tangential movement downburst wind profile, based on full-scale computational fluid dynamics (Computational Fluid Dynamics, CFD) analog result, the wind speed computing formula of downburst has been proposed, for engineering design provides theoretical reference, form is succinct, precision is high, and calculates efficient.

In order to realize the foregoing invention purpose, the present invention takes following technical scheme:

A kind of method of definite tangential movement downburst wind profile is provided, said method comprising the steps of:

Step 1: the Jet model of simulation downburst;

Step 2: Jet model is converted into to the numerical evaluation model;

Step 3: determine tangential movement downburst wind profile.

In described step 1, based on computational fluid dynamics, and the Jet model of employing three dimensional N-S equation simulation tangential movement downburst, by RSM turbulence model sealing three dimensional N-S equation.

Described three dimensional N-S equation comprises mass equation and the equation of momentum;

Wherein mass equation is:

$\frac{\∂\mathrm{\ρ}}{\∂t}+\frac{\∂\left({\mathrm{\ρu}}_i\right)}{{\∂x}_i}=0---\left(1\right)$

The equation of momentum is:

$\frac{\∂}{\∂t}\left(\mathrm{\ρ}{u}_i\right)+\frac{\∂}{\∂x_j}\left(\mathrm{\ρ}{u}_i{u}_j\right)=-\frac{\∂p}{\∂x_i}+\frac{\∂}{\∂x_j}\left[\mathrm{\μ}(\frac{\∂u_i}{\∂x_j}+\frac{\∂u_j}{\∂x_i}-\frac{2}{3}{\mathrm{\δ}}_{\mathrm{ij}}\frac{\∂u_l}{\∂x_l})\right]+\frac{\∂}{\∂x_j}(-\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}})---\left(2\right)$

Wherein, ρ is atmospheric density; P is atmospheric pressure; μ is kinetic viscosity; u _i, u _jand u _lbe the speed component of tensor form, u ' _iand u ' _jbe the velocity fluctuation component of tensor form, and i, j and l separate, all desirable 1,2 and 3, i get 1,2 and at 3 o'clock, u _ithe corresponding u that gets ₁, u ₂and u ₃mean respectively under rectangular coordinate system the speed component along x, y and z direction; δ _ijfor tensor operator, and meet ${\mathrm{\δ}}_{\mathrm{ij}}=\left\{\begin{array}{cc}1& i=j\\ 0& i\≠j\end{array}\right.;$

The transport equation of described RSM turbulence model is:

$\frac{\∂}{\∂t}\left(\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)+\frac{\∂}{{\∂x}_k}\left({\mathrm{\ρu}}_k\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)=-\frac{\∂}{{\∂x}_k}[\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}{u}_k^{\′}}+\stackrel{\‾}{p^{\′}({\mathrm{\δ}}_{\mathrm{kj}}{u}_i^{\′}+{\mathrm{\δ}}_{\mathrm{ik}}{u}_j^{\′})}]$

$+\frac{\∂}{{\∂x}_k}\left[\mathrm{\μ}\frac{\∂}{{\∂x}_k}\left(\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)\right]-\mathrm{\ρ}(\stackrel{\‾}{u_i^{\′}{u}_k^{\′}}\frac{{\∂u}_j}{{\∂x}_k}+\stackrel{\‾}{u_j^{\′}{u}_k^{\′}}\frac{{\∂u}_i}{{\∂x}_k})+p^{\′}(\frac{{\∂u}_i^{\′}}{{\∂x}_j}+\frac{{\∂u}_j^{\′}}{{\∂x}_i})---\left(3\right)$

$-2\mathrm{\μ}\stackrel{\‾}{\frac{{\∂u}_i^{\′}}{{\∂x}_k}\frac{{\∂u}_j^{\′}}{{\∂x}_k}}-{2\mathrm{\ρ\Ω}}_k(\stackrel{\‾}{u_j^{\′}{u}_m^{\′}}{\mathrm{\ϵ}}_{\mathrm{ikm}}+\stackrel{\‾}{u_i^{\′}{u}_m^{\′}}{\mathrm{\ϵ}}_{\mathrm{jkm}})$

Wherein, u _kand u _mbe the speed component of tensor form, u ' _kand u ' _mbe the velocity fluctuation component of tensor form, and k and m separate, all desirable 1,2 and 3; Ω _kfor symmetrical velocity gradient tensor; P ' is the atmospheric pressure percent ripple; δ _kj, δ _ik, ε _ikmand ε _jkmbe tensor operator, and meet respectively: ${\mathrm{\δ}}_{\mathrm{kj}}=\left\{\begin{array}{cc}1& k=j\\ 0& k\≠j\end{array}\right.;$ ${\mathrm{\δ}}_{\mathrm{ik}}=\left\{\begin{array}{cc}1& k=i\\ 0& k\≠i\end{array}\right.;$

Transport equation by three dimensional N-S equation and RSM turbulence model is determined atmospheric density ρ, atmospheric pressure p, under rectangular coordinate system respectively along the speed component u of x, y and z direction ₁, u ₂and u ₃, and eddy stress

eddy stress

comprise normal stress and shearing stress; Normal stress comprises under rectangular coordinate system the normal stress along x, y and z direction

with

shearing stress comprises perpendicular to the x face points to the axial shearing stress of y

point to the axial shearing stress of x perpendicular to the y face

point to the axial shearing stress of z perpendicular to the x face point to the axial shearing stress of x perpendicular to the z face

point to the axial shearing stress of z perpendicular to the y face

with point to the axial shearing stress of y perpendicular to the z face

Due to the symmetry of tensor, numerically, meet $\mathrm{\ρ}\stackrel{\‾}{u_2^{\′}{u}_1^{\′}}=\mathrm{\ρ}\stackrel{\‾}{u_1^{\′}{u}_2^{\′}},$ $\mathrm{\ρ}\stackrel{\‾}{u_3^{\′}{u}_1^{\′}}=\mathrm{\ρ}\stackrel{\‾}{u_1^{\′}{u}_3^{\′}},$ $\mathrm{\ρ}\stackrel{\‾}{u_3^{\′}{u}_{\text{2}}^{\′}}=\mathrm{\ρ}\stackrel{\‾}{u_2^{\′}{u}_3^{\′}}.$

Described step 2 Jet model is converted in the numerical evaluation model, utilize boundary condition to apply calculating parameter; Described boundary condition comprises downburst speed entrance, pressure export and without slippage ground;

Described calculating parameter comprises downburst entrance height, inlet diameter, inlet velocity and tangential movement speed.

Described step 3 comprises the following steps:

Step 3-1: wind profile is carried out to the nondimensionalization processing;

Step 3-2: the wind speed V ' of calculated level motion downburst _r,T.

In described step 3-1, utilize the u of inlet velocity to calculating of downburst ₂carry out nondimensionalization, and the inlet diameter that utilizes downburst carries out nondimensionalization to the z coordinate of downburst.

In described step 3-2, adopt the wind speed V ' of Nonlinearity Correction Method calculated level motion downburst _r,T;

V ' _r,Tbe expressed as:

V′ _R,T＝V _R+f(R)×U _t （4）

Wherein, V _rfor the wind speed of the static downburst at corresponding R place, position, and meet V _r=u ₂; U _tfor downburst tangential movement speed, wherein f (R) is expressed as:

$f\left(R\right)=\left\{\begin{array}{cc}1+[1-\mathrm{erf}\left(R\right)]\×(R_{u\max }-R)+e^{{-(R_{u\max }-R)}^2}\×{(R_{u\max }-R)}^2& \mathrm{if}(R\≤R_{u\max })\\ 1.0& \mathrm{if}(R>R_{u\max })\end{array}\right.----\left(5\right)$

Wherein, R _umaxfor the radial coordinate of maximum horizontal wind speed, erf (R) is expressed as:

$\mathrm{erf}\left(R\right)=\frac{2\left({\∫}_0^R{e}^{{-t}^2}\mathrm{dt}\right)}{\sqrt{\mathrm{\π}}}---\left(6\right)$

Wherein, erf (R) means the error function at corresponding R place, position.

Compared with prior art, beneficial effect of the present invention is:

(1) form is succinct; Only adopt simple function to describe modifying factor;

(2) calculate efficiently; The time of tangential movement downburst computational fluid dynamics simulation is than these formula at least large 4 magnitudes computing time;

(3) precision is high; In the high wind altitude range of downburst, the wind profile CFD result of the result that adopts this formula to calculate and tangential movement downburst is coincide fine, and computational accuracy is high;

(4) Consideration is thorough; While adopting CFD simulation flow field, the mobile non-linear characteristics of downburst and non-size effect have been taken into full account to non-linear mobile impact.

The accompanying drawing explanation

Fig. 1 is the flow schematic diagram of the Jet model of downburst in the embodiment of the present invention;

Fig. 2 is based on downburst numerical evaluation model schematic diagram and the boundary condition schematic diagram of Jet model;

Fig. 3 is the nondimensional velocity diagrammatic cross-section of R/D=0.6 position in the embodiment of the present invention;

Fig. 4 is the nondimensional velocity diagrammatic cross-section of R/D=0.8 position in the embodiment of the present invention;

Fig. 5 is the nondimensional velocity diagrammatic cross-section of R/D=1.0 position in the embodiment of the present invention;

Fig. 6 is the nondimensional velocity diagrammatic cross-section of R/D=1.5 position in the embodiment of the present invention;

Fig. 7 is the nondimensional velocity diagrammatic cross-section of R/D=2.5 position in the embodiment of the present invention;

Fig. 8 is the nondimensional velocity cross-section linear correction result schematic diagram of R/D=0.6 position in the embodiment of the present invention;

Fig. 9 is the nondimensional velocity cross-section linear correction result schematic diagram of R/D=0.8 position in the embodiment of the present invention;

Figure 10 is the nondimensional velocity cross-section linear correction result schematic diagram of R/D=1.0 position in the embodiment of the present invention;

Figure 11 is the nondimensional velocity cross-section linear correction result schematic diagram of R/D=1.5 position in the embodiment of the present invention;

Figure 12 is the nondimensional velocity cross-section linear correction result schematic diagram of R/D=2.5 position in the embodiment of the present invention;

Figure 13 is the non-linear correction result schematic diagram of the nondimensional velocity section of R/D=0.6 position in the embodiment of the present invention;

Figure 14 is the non-linear correction result schematic diagram of the nondimensional velocity section of R/D=0.8 position in the embodiment of the present invention;

Figure 15 is the non-linear correction result schematic diagram of the nondimensional velocity section of R/D=1.0 position in the embodiment of the present invention;

Figure 16 is the non-linear correction result schematic diagram of the nondimensional velocity section of R/D=1.5 position in the embodiment of the present invention;

Figure 17 is the non-linear correction result schematic diagram of the nondimensional velocity section of R/D=2.5 position in the embodiment of the present invention.

Embodiment

Below in conjunction with accompanying drawing, the present invention is described in further detail.

A kind of method of definite tangential movement downburst wind profile is provided, said method comprising the steps of:

Step 1: the Jet model of simulation downburst;

Step 2: Jet model is converted into to the numerical evaluation model;

Step 3: determine tangential movement downburst wind profile.

In described step 1, based on computational fluid dynamics, and the Jet model of employing three dimensional N-S equation simulation tangential movement downburst, by RSM turbulence model sealing three dimensional N-S equation.While adopting Jet model simulation downburst, air-flow sprays from the mouth of pipe earthward with certain speed, and after striking ground, to the surrounding diffluence.The flow schematic diagram of this Jet model as shown in Figure 1.

Described three dimensional N-S equation comprises mass equation and the equation of momentum; Be recorded in John D.Anderson Jr., Joris Degroote, Gerard Degrez, Erik Dick, Roger Grundmann and Jan Vierendeels, Computational Fluid Dynamics-An Introduction (3rd Edition,), Springer-Verlag Berlin Heidelberg1992,1996,2009.

Wherein mass equation is:

$\frac{\∂\mathrm{\ρ}}{\∂t}+\frac{\∂\left({\mathrm{\ρu}}_i\right)}{{\∂x}_i}=0---\left(1\right)$

The equation of momentum is:

$\frac{\∂}{\∂t}\left(\mathrm{\ρ}{u}_i\right)+\frac{\∂}{\∂x_j}\left(\mathrm{\ρ}{u}_i{u}_j\right)=-\frac{\∂p}{\∂x_i}+\frac{\∂}{\∂x_j}\left[\mathrm{\μ}(\frac{\∂u_i}{\∂x_j}+\frac{\∂u_j}{\∂x_i}-\frac{2}{3}{\mathrm{\δ}}_{\mathrm{ij}}\frac{\∂u_l}{\∂x_l})\right]+\frac{\∂}{\∂x_j}(-\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}})---\left(2\right)$

Wherein, ρ is atmospheric density; P is atmospheric pressure; μ is kinetic viscosity; u _i, u _jand u _lbe the speed component of tensor form, u ' _iand u ' _jbe the velocity fluctuation component of tensor form, and i, j and l separate, all desirable 1,2 and 3, i get 1,2 and at 3 o'clock, u _ithe corresponding u that gets ₁, u ₂and u ₃mean respectively under rectangular coordinate system the speed component along x, y and z direction; δ _ijfor tensor operator, and meet ${\mathrm{\δ}}_{\mathrm{ij}}=\left\{\begin{array}{cc}1& i=j\\ 0& i\≠j\end{array}\right.;$

The transport equation of described RSM turbulence model is recorded in B.E.Launder, G.J.Reece, and W.Rodi. " Progress in the Development of a Reynolds-Stress Turbulence Closure " .J.Fluid Mech..68 (3) .537 – 566.April1975, transport equation is specially:

$\frac{\∂}{\∂t}\left(\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)+\frac{\∂}{{\∂x}_k}\left({\mathrm{\ρu}}_k\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)=-\frac{\∂}{{\∂x}_k}[\mathrm{\ρ}\stackrel{\‾}{u_i^{\′}{u}_j^{\′}{u}_k^{\′}}+\stackrel{\‾}{p^{\′}({\mathrm{\δ}}_{\mathrm{kj}}{u}_i^{\′}+{\mathrm{\δ}}_{\mathrm{ik}}{u}_j^{\′})}]$

$+\frac{\∂}{{\∂x}_k}\left[\mathrm{\μ}\frac{\∂}{{\∂x}_k}\left(\stackrel{\‾}{u_i^{\′}{u}_j^{\′}}\right)\right]-\mathrm{\ρ}(\stackrel{\‾}{u_i^{\′}{u}_k^{\′}}\frac{{\∂u}_j}{{\∂x}_k}+\stackrel{\‾}{u_j^{\′}{u}_k^{\′}}\frac{{\∂u}_i}{{\∂x}_k})+p^{\′}(\frac{{\∂u}_i^{\′}}{{\∂x}_j}+\frac{{\∂u}_j^{\′}}{{\∂x}_i})---\left(3\right)$

$-2\mathrm{\μ}\stackrel{\‾}{\frac{{\∂u}_i^{\′}}{{\∂x}_k}\frac{{\∂u}_j^{\′}}{{\∂x}_k}}-{2\mathrm{\ρ\Ω}}_k(\stackrel{\‾}{u_j^{\′}{u}_m^{\′}}{\mathrm{\ϵ}}_{\mathrm{ikm}}+\stackrel{\‾}{u_i^{\′}{u}_m^{\′}}{\mathrm{\ϵ}}_{\mathrm{jkm}})$

Wherein, u _kand u _mbe the speed component of tensor form, u ' _kand u ' _mbe the velocity fluctuation component of tensor form, and k and m separate, all desirable 1,2 and 3; Ω _kfor symmetrical velocity gradient tensor; P ' is the atmospheric pressure percent ripple; δ _kj, δ _ik, ε _ikmand ε _jkmbe tensor operator, and meet respectively: ${\mathrm{\δ}}_{\mathrm{kj}}=\left\{\begin{array}{cc}1& k=j\\ 0& k\≠j\end{array}\right.;$ ${\mathrm{\δ}}_{\mathrm{ik}}=\left\{\begin{array}{cc}1& k=i\\ 0& k\≠i\end{array}\right.;$

Transport equation by three dimensional N-S equation and RSM turbulence model is determined atmospheric density ρ, atmospheric pressure p, under rectangular coordinate system respectively along the speed component u of x, y and z direction ₁, u ₂and u ₃, and eddy stress eddy stress

comprise normal stress and shearing stress; Normal stress comprises under rectangular coordinate system the normal stress along x, y and z direction

with

shearing stress comprises perpendicular to the x face points to the axial shearing stress of y

point to the axial shearing stress of x perpendicular to the y face

point to the axial shearing stress of z perpendicular to the x face

point to the axial shearing stress of x perpendicular to the z face

point to the axial shearing stress of z perpendicular to the y face

with point to the axial shearing stress of y perpendicular to the z face

Due to the symmetry of tensor, numerically, meet $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_2^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="HDA00003375295500021.png,HDA00003375295500022.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_1^{\&prime;}{u}_2^{\&prime;}},$ $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_3^{\&prime;}{\mathrm{<figure-callout\; id="1"\; label="u"\; filenames="HDA00003375295500021.png,HDA00003375295500022.png"\; state="\{\{state\}\}">u</figure-callout>}}_1^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_1^{\&prime;}{u}_3^{\&prime;}},$ $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_3^{\&prime;}{u}_{\text{2}}^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_2^{\&prime;}{u}_3^{\&prime;}}.$

Described step 2 Jet model is converted in the numerical evaluation model, utilize boundary condition to apply calculating parameter; Described boundary condition comprises downburst speed entrance, pressure export and without slippage ground; Downburst numerical evaluation model schematic diagram based on Jet model and relevant border condition as shown in Figure 2, are specially: air-flow flows into perpendicular to the speed inlet boundary with constant speed; Without slippage ground with tangential movement speed U _twith respect to the translation of downburst entrance, and U _t=0 means static downburst; The pressure export boundary condition, environmental pressure is set to atmospheric pressure.

Described calculating parameter comprises downburst entrance height, inlet diameter D, inlet velocity and tangential movement speed.

According to downburst meteorological observation result, selected downburst entrance height is 2100m, and inlet diameter D is 1600m, and inlet velocity is 70m/s.Its tangential movement speed U _tbe respectively 6m/s, 12m/s and 18m/s.The nondimensional velocity section of the full-scale downburst calculated as shown in accompanying drawing 3-Fig. 7, wherein, V _r=u ₂, V _inbe inlet velocity, its value is V _in=70m/s.

Described step 3 comprises the following steps:

Step 3-1: wind profile is carried out to the nondimensionalization processing;

Step 3-2: the wind speed V ' of calculated level motion downburst _r,T.

In described step 3-1, utilize the u of inlet velocity to calculating of downburst ₂carry out nondimensionalization, and the inlet diameter that utilizes downburst carries out nondimensionalization to the z coordinate of downburst.

In described step 3-2, the wind profile result calculated is relatively as shown in Fig. 8-Figure 12.From curve relatively, at R≤R _umaxin between radial portion, the velocity profile obtained based on linear revise and static wind profile resultant error are larger.The present invention adopts Nonlinearity Correction Method, and according to dimensional analysis, the dimension of this correction term is [m/s], and the size of correction is directly related with translational velocity, chooses translational velocity U for this reason _ta part as correction term; Also consider the nonlinear velocity distribution character of downburst horizontal velocity in its colliding surface process, therefore also needing to introduce a nonlinear factor describes this variation tendency simultaneously, and this coefficient is the function of radial position R.Finally obtain the wind speed V ' of calculated level motion downburst _r,Texpression formula.

V ' _r,Tbe expressed as:

V′ _R,T＝V _R+f(R)×U _t （4）

Wherein, V _rfor the wind speed of the static downburst at corresponding R place, position, and meet V _r=u ₂; U _tfor downburst tangential movement speed, according to the error characteristics of Fig. 8-Figure 12, determine that f (R) consists of two sections functions.And consider that error is at R≤R _umaxreduce along with the increase of R in interval, therefore adopt (R _umax-R) and [1-erf (R)] carry out this attenuation characteristic of characterized.F (R) is expressed as:

$f\left(R\right)=\left\{\begin{array}{cc}1+[1-\mathrm{erf}\left(R\right)]\&times;(R_{u\max }-R)+e^{{-(R_{u\max }-R)}^2}\&times;{(R_{u\max }-R)}^2& \mathrm{if}(R\&le;R_{u\max })\\ 1.0& \mathrm{if}(R>R_{u\max })\end{array}\right.----\left(5\right)$

Wherein, R _umaxfor the radial coordinate of maximum horizontal wind speed, erf (R) is expressed as:

$\mathrm{erf}\left(R\right)=\frac{2\left({\&Integral;}_0^R{e}^{{-t}^2}\mathrm{dt}\right)}{\sqrt{\mathrm{\&pi;}}}---\left(6\right)$

Wherein, erf (R) means the error function at corresponding R place, position.

The revised wind profile result of application of formula (4) is as shown in accompanying drawing 13-Figure 17.

Result by relatively linear revise and non-linear correction is known, and after adopting Nonlinearity Correction Method, the downburst wind profile of tangential movement and static wind profile coincide fine, can be for engineering design.

Finally should be noted that: above embodiment is only in order to illustrate that technical scheme of the present invention is not intended to limit, although with reference to above-described embodiment, the present invention is had been described in detail, those of ordinary skill in the field are to be understood that: still can modify or be equal to replacement the specific embodiment of the present invention, and do not break away from any modification of spirit and scope of the invention or be equal to replacement, it all should be encompassed in the middle of claim scope of the present invention.

Claims (7)

1. the method for a definite tangential movement downburst wind profile is characterized in that: said method comprising the steps of:

Step 1: the Jet model of simulation downburst;

Step 2: Jet model is converted into to the numerical evaluation model;

Step 3: determine tangential movement downburst wind profile.

2. the method for definite tangential movement downburst wind profile according to claim 1, it is characterized in that: in described step 1, based on computational fluid dynamics, and the Jet model of employing three dimensional N-S equation simulation tangential movement downburst, by RSM turbulence model sealing three dimensional N-S equation.

3. the method for definite tangential movement downburst wind profile according to claim 2, it is characterized in that: described three dimensional N-S equation comprises mass equation and the equation of momentum;

Wherein mass equation is:

$\frac{\&PartialD;\mathrm{\&rho;}}{\&PartialD;t}+\frac{\&PartialD;\left({\mathrm{\&rho;u}}_i\right)}{{\&PartialD;x}_i}=0---\left(1\right)$

The equation of momentum is:

$\frac{\&PartialD;}{\&PartialD;t}\left(\mathrm{\&rho;}{u}_i\right)+\frac{\&PartialD;}{\&PartialD;x_j}\left(\mathrm{\&rho;}{u}_i{u}_j\right)=-\frac{\&PartialD;p}{\&PartialD;x_i}+\frac{\&PartialD;}{\&PartialD;x_j}\left[\mathrm{\&mu;}(\frac{\&PartialD;u_i}{\&PartialD;x_j}+\frac{\&PartialD;u_j}{\&PartialD;x_i}-\frac{2}{3}{\mathrm{\&delta;}}_{\mathrm{ij}}\frac{\&PartialD;u_l}{\&PartialD;x_l})\right]+\frac{\&PartialD;}{\&PartialD;x_j}(-\mathrm{\&rho;}\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_j^{\&prime;}})---\left(2\right)$

Wherein, ρ is atmospheric density; P is atmospheric pressure; μ is kinetic viscosity; u _i, u _jand u _lbe the speed component of tensor form, u ' _iand u ' _jbe the velocity fluctuation component of tensor form, and i, j and l separate, all desirable 1,2 and 3, i get 1,2 and at 3 o'clock, u _ithe corresponding u that gets ₁, u ₂and u ₃mean respectively under rectangular coordinate system the speed component along x, y and z direction; δ _ijfor tensor operator, and meet ${\mathrm{\&delta;}}_{\mathrm{ij}}=\left\{\begin{array}{cc}1& i=j\\ 0& i\&NotEqual;j\end{array}\right.;$

The transport equation of described RSM turbulence model is:

$\frac{\&PartialD;}{\&PartialD;t}\left(\mathrm{\&rho;}\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_j^{\&prime;}}\right)+\frac{\&PartialD;}{{\&PartialD;x}_k}\left({\mathrm{\&rho;u}}_k\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_j^{\&prime;}}\right)=-\frac{\&PartialD;}{{\&PartialD;x}_k}[\mathrm{\&rho;}\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_j^{\&prime;}{u}_k^{\&prime;}}+\stackrel{\&OverBar;}{p^{\&prime;}({\mathrm{\&delta;}}_{\mathrm{kj}}{u}_i^{\&prime;}+{\mathrm{\&delta;}}_{\mathrm{ik}}{u}_j^{\&prime;})}]$

$+\frac{\&PartialD;}{{\&PartialD;x}_k}\left[\mathrm{\&mu;}\frac{\&PartialD;}{{\&PartialD;x}_k}\left(\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_j^{\&prime;}}\right)\right]-\mathrm{\&rho;}(\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_k^{\&prime;}}\frac{{\&PartialD;u}_j}{{\&PartialD;x}_k}+\stackrel{\&OverBar;}{u_j^{\&prime;}{u}_k^{\&prime;}}\frac{{\&PartialD;u}_i}{{\&PartialD;x}_k})+p^{\&prime;}(\frac{{\&PartialD;u}_i^{\&prime;}}{{\&PartialD;x}_j}+\frac{{\&PartialD;u}_j^{\&prime;}}{{\&PartialD;x}_i})---\left(3\right)$

$-2\mathrm{\&mu;}\stackrel{\&OverBar;}{\frac{{\&PartialD;u}_i^{\&prime;}}{{\&PartialD;x}_k}\frac{{\&PartialD;u}_j^{\&prime;}}{{\&PartialD;x}_k}}-{2\mathrm{\&rho;\&Omega;}}_k(\stackrel{\&OverBar;}{u_j^{\&prime;}{u}_m^{\&prime;}}{\mathrm{\&epsiv;}}_{\mathrm{ikm}}+\stackrel{\&OverBar;}{u_i^{\&prime;}{u}_m^{\&prime;}}{\mathrm{\&epsiv;}}_{\mathrm{jkm}})$

Wherein, u _kand u _mbe the speed component of tensor form, u ' _kand u ' _mbe the velocity fluctuation component of tensor form, and k and m separate, all desirable 1,2 and 3; Ω _kfor symmetrical velocity gradient tensor; P ' is the atmospheric pressure percent ripple; δ _kj, δ _ik, ε _ikmand ε _jkmbe tensor operator, and meet respectively: ${\mathrm{\&delta;}}_{\mathrm{kj}}=\left\{\begin{array}{cc}1& k=j\\ 0& k\&NotEqual;j\end{array}\right.;$ ${\mathrm{\&delta;}}_{\mathrm{ik}}=\left\{\begin{array}{cc}1& k=i\\ 0& k\&NotEqual;i\end{array}\right.;$

Transport equation by three dimensional N-S equation and RSM turbulence model is determined atmospheric density ρ, atmospheric pressure p, under rectangular coordinate system respectively along the speed component u of x, y and z direction ₁, u ₂and u ₃, and eddy stress

eddy stress

comprise normal stress and shearing stress; Normal stress comprises under rectangular coordinate system the normal stress along x, y and z direction with

shearing stress comprises perpendicular to the x face points to the axial shearing stress of y

point to the axial shearing stress of x perpendicular to the y face

point to the axial shearing stress of z perpendicular to the x face

point to the axial shearing stress of x perpendicular to the z face

point to the axial shearing stress of z perpendicular to the y face

with point to the axial shearing stress of y perpendicular to the z face

Due to the symmetry of tensor, numerically, meet $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_2^{\&prime;}{u}_1^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_1^{\&prime;}{u}_2^{\&prime;}},$ $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_3^{\&prime;}{u}_1^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_1^{\&prime;}{u}_3^{\&prime;}},$ $\mathrm{\&rho;}\stackrel{\&OverBar;}{u_3^{\&prime;}{u}_{\text{2}}^{\&prime;}}=\mathrm{\&rho;}\stackrel{\&OverBar;}{u_2^{\&prime;}{u}_3^{\&prime;}}.$

4. the method for definite tangential movement downburst wind profile according to claim 1 is characterized in that: described step 2 Jet model is converted in the numerical evaluation model, utilize boundary condition to apply calculating parameter; Described boundary condition comprises downburst speed entrance, pressure export and without slippage ground;

Described calculating parameter comprises downburst entrance height, inlet diameter, inlet velocity and tangential movement speed.

5. the method for definite tangential movement downburst wind profile according to claim 1, it is characterized in that: described step 3 comprises the following steps:

Step 3-1: wind profile is carried out to the nondimensionalization processing;

Step 3-2: the wind speed V ' of calculated level motion downburst _r,T.

6. the method for definite tangential movement downburst wind profile according to claim 5, is characterized in that: in described step 3-1, utilize the u of inlet velocity to calculating of downburst ₂carry out nondimensionalization, and the inlet diameter that utilizes downburst carries out nondimensionalization to the z coordinate of downburst.

7. the method for definite tangential movement downburst wind profile according to claim 5, is characterized in that: in described step 3-2, adopt the wind speed V ' of Nonlinearity Correction Method calculated level motion downburst _r,T;

V ' _r,Tbe expressed as:

V′ _R,T＝V _R+f(R)×U _t （4）

Wherein, V _rfor the wind speed of the static downburst at corresponding R place, position, and meet V _r=u ₂; U _tfor downburst tangential movement speed, wherein f (R) is expressed as:

$f\left(R\right)=\left\{\begin{array}{cc}1+[1-\mathrm{erf}\left(R\right)]\&times;(R_{u\max }-R)+e^{{-(R_{u\max }-R)}^2}\&times;{(R_{u\max }-R)}^2& \mathrm{if}(R\&le;R_{u\max })\\ 1.0& \mathrm{if}(R>R_{u\max })\end{array}\right.----\left(5\right)$

Wherein, R _umaxfor the radial coordinate of maximum horizontal wind speed, erf (R) is expressed as:

$\mathrm{erf}\left(R\right)=\frac{2\left({\&Integral;}_0^R{e}^{{-t}^2}\mathrm{dt}\right)}{\sqrt{\mathrm{\&pi;}}}---\left(6\right)$

Wherein, erf (R) means the error function at corresponding R place, position.

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