JPH11173942A - Method for estimating maximum landing concentration - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make estimable a maximum landing concentration generated in a place beyond the measurement limit distance on the lee side by calculating with the use of a specific formula on the basis of data of wind tunnel experiments within the measurement limit distance on the lee side. SOLUTION: Based on data of wind tunnel experiments within the range of a measurement limit distance Xd on the lee side, an estimated horizontal dispersion width σy (X) at a position of a lee distance exceeding the range of the distance Xd, an estimated vertical dispersion width σz (X), an estimated effective chimney height He, a quantity Q of gas emitted from the same chimney model, and a wind velocity Y in a wind tunnel are substituted in a ground surface concentration calculation expression C(X)=[Q/ π.σy (X).σz (X).U}]exp[-He<2> / 2σz (X)<2> }]. The ground surface concentration C(X) is thus obtained. A maximum value of the concentration is set as a maximum ground surface concentration. Accordingly, a maximum landing concentration generated in the place beyond the distance of the measurement limit distance on the lee side which could not be investigated from model experiments can be estimated on the basis of experimental data obtained through investigating by wind tunnel experiments within the measurement limit distance on the lee side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of estimating the maximum landing concentration of an actual gas by simulating the diffusion of gas discharged into the atmosphere by a wind tunnel experiment.

[0002]

2. Description of the Related Art FIG. 1 (1) is a longitudinal sectional view of a conventional wind tunnel test apparatus showing a situation in which a test gas is discharged from a chimney model in a wind tunnel to perform a wind tunnel test and to investigate an influence on a surface object. FIG. 1 (2) is a graph showing the distribution of the test gas landing concentration in the leeward direction in the wind tunnel experiment of FIG. 1 (1), and FIG. 2 (1) is a graph showing the rise height Δh of the test gas with respect to the distance X in the leeward direction. 2 (2) is a graph showing the vertical diffusion width σ _z of the test gas at the leeward distance X ′ in FIG. 2 (1), and FIG. 3 is the rise of the test gas with respect to the leeward distance X. FIG. 4 is a graph showing a change in height Δh in a case where a surface object is present and a case where there is no surface object, and FIG. vertical diffusion widths sigma _zp of the test gas in the absence of the diffusion widths sigma _zt and surface material It is a graph showing a comparison.

First, in the wind tunnel shown in FIG. 1A, the wind tunnel can send a uniform flow 1 of airflow from the upstream side of the measurement chamber 2 into the measurement chamber 2 during a wind tunnel experiment. Measurement room 2
A ground surface model having a chimney model 3 and a building model 5 is installed therein, and a test gas 4 as flue gas is discharged or released from the chimney model 3 so that a wind tunnel experiment can be performed. I have.

By the way, using the wind tunnel shown in FIG. 1 (1), the flow and diffusion of the flue gas having thermal buoyancy discharged or released from the actual chimney into the atmosphere are generated on the surrounding ground surface. In order to investigate the effect of the building on the ground, a simulation test using a surface model such as the chimney model 3 or the building model 5 will be performed. It is necessary to extremely increase the scale of the model scale required for reproduction in the interior.

In this case, since the length of the measurement chamber 2 in the wind tunnel is limited, the range from the arrival of the smoke exhaust to the appearance of the maximum concentration on the ground surface, for example, the leeward distance from the actual chimney is several km.
It is generally difficult to investigate the flow and diffusion of smoke exhaust gas in the range of up to tens of kilometers by wind tunnel experiments. For example, even if an attempt is made to investigate the flow and diffusion of flue gas in the range from the time when the flue gas lands on the wind tunnel in FIG. It is only possible to investigate the flow and diffusion of flue gas in the range from the model 3 to the measurement downwind distance X = Xd. FIG.
(2) is an occurrence point Xmax of the maximum landing concentration Cmax
However, normally, Xmax> Xd, which is outside the range of the measurement room 2 in the wind tunnel, indicating that it is difficult to predict the maximum landing concentration in the wind tunnel experiment.

[0006]

Therefore, as shown in FIGS. 2 (1) and 2 (2), conventionally, an experiment was carried out in the case where a surface object was present and in the case where no surface object was present, and the concentration data was obtained. , The locus of the maximum concentration point in a plane perpendicular to the flow direction of the test gas as flue gas, that is, the height of the smoke axis rising from the outlet of the chimney model 3 of the smoke axis a, and the height of the smoke axis rising from the smoke axis. Then, the vertical diffusion width σ _{z at} the position of the leeward distance X ′, which is h, is obtained, and as shown in FIG.
For h and the vertical diffusion width σ _z , a comparison is made between the case where there is a surface feature as shown by a graph passing through a triangle △ and the case where there is no surface feature as shown by a graph passing through a circle 〇. He discussed the impact of the presence of objects when compared to the absence of surface features.

As shown in FIG. 3, conventionally, when discussing the influence of surface objects on smoke emission, for example, regarding the height of the smoke axis Δh, a graph of the height of the smoke axis when there is no surface object is shown. in certain calculations predetermined smoke shaft increases the height obtained by equation △ h _p straight and downwind distance point of intersection representative of the Xo, to calculate the smoke-axis height of rise △ h _t when a surface thereof, a predetermined smoke shaft find the ratio of smoke shaft rising height △ h _t when a surface thereof for increasing the height △ h _p, according to the value or the like of the ratio thus determined was discussed the effects of the smoke of surface thereof.

[0010] As shown in FIG. 4, when discussing the effect of surface objects on smoke emission, the vertical diffusion width σ _z is as follows.
For gas released under the same conditions, the vertical diffusion width σ _zt when there is a surface object as shown by the graph passing through the triangle △, and when there is no surface object as shown by the graph passing through the circle 〇 The vertical diffusion width σ _zp was compared at each leeward distance to discuss the effect of surface objects on smoke emission.

[0009] However, in the above discussion, although it is known whether or not the building has an effect on smoke emission, it is not possible to rigorously evaluate whether or not the influence is a matter of concern. When discussing the spread of water, it is necessary to predict the maximum landing concentration that will appear on the ground.

[0010] In view of the above circumstances, the present invention provides an investigation by a wind tunnel experiment within a measurement limit leeward distance even if it is impossible to investigate a leeward distance at which the maximum concentration appears on the ground surface by a model experiment. Method for estimating the maximum landing concentration that occurs beyond the measurement limit downwind distance, which could not be investigated by the model experiment, based on the experimental data obtained by What you want to do.

The present invention combines the maximum landing density, which was difficult to predict only with a wind tunnel experiment, with experimental data obtained by a wind tunnel experiment within the measurement limit downwind distance, and a calculation formula. An object of the present invention is to provide a method for estimating a maximum landing density that can be estimated beyond a measurement limit downwind distance and a maximum landing density occurrence distance that could not be investigated by the model experiment. It is.

Furthermore, the present invention combines the maximum landing concentration, which was difficult to predict only with a wind tunnel experiment, with experimental data obtained by a wind tunnel experiment within the measurement limit downwind distance and a calculation formula. The maximum landing concentration that occurs beyond the measurement downwind distance and the maximum landing concentration occurrence distance that could not be investigated by the model experiment can be estimated, and the calculation formula used in the environmental assessment depends on the surface It is an object of the present invention to provide a method for estimating the maximum landing density, which can incorporate the influence.

[0013]

In order to solve the above-mentioned problems, a method for estimating a maximum landing concentration according to the present invention is to install a ground surface model in a wind tunnel, discharge a test gas from a chimney model in the wind tunnel, and wind the wind tunnel. A maximum landing concentration estimation method for performing an experiment and estimating an actual maximum landing concentration of a gas, wherein a discharge position of the test gas from the chimney model is set as a coordinate origin, and an x-axis in a leeward direction and a direction orthogonal to the x-axis. Taking the y-axis in the horizontal direction and the z-axis in the vertical direction, let x be the distance in the x-axis direction from the origin, and measure the y of the test gas measured at a plurality of points in the x-axis direction without installing the ground model. The horizontal diffusion width σ _yf (X) and the ground model of the test gas at the arbitrary leeward distance X obtained based on the axial diffusion width in the axial direction and the vertical diffusion width in the z-axis direction without the surface model are Vertical diffusion width σ _zf (X) And the above-described test at an arbitrary leeward distance X obtained based on the diffusion width in the y-axis direction and the diffusion width in the z-axis direction of the test gas measured at a plurality of points in the x-axis direction with the ground model placed. The horizontal diffusion width σ _yt (X) when the gas surface model is present, the vertical diffusion width σ _zt (X) when the surface model is present, and the surface model at any downwind distance X of the test gas is not available. The x-coordinate X _{1 of the} point where the curve drawn by the horizontal diffusion width σ _yf (X) in the case and the curve drawn by the horizontal diffusion width σ _yt (X) when the ground model is present, Vertical diffusion width σ _zf (X) without the above ground model at an arbitrary distance X and vertical diffusion width σ _zt (X) without the above ground model
[Mathematical formula 1] according to the x coordinate X _{2 of the} point where

## EQU1 ## σ _y (X) = σ _yt (X): X <X ₁ σ _y (X) = σ _yf (X): X> X ₁ σ _z (X) = σ _zt (X): X < X ₂ σ _z (X) = σ _zf (X): The horizontal diffusion width σ _y (X) and the vertical diffusion width σ _z (X) of the test gas obtained by X> X ₂ and the above ground model Represents the height △ h _f (X) of rise of the test gas from the chimney model for an arbitrary distance X determined based on the height of rise of the test gas measured at a plurality of points in the x-axis direction without being installed. using increase the height △ h _t of the test gas in the case where there is the surface model in the curve with a predetermined straight line and the x-coordinate Xo of points intersect each other representing the height increases, the height Ho of the chimney model And [Equation 2], that is,

He = Ho + △ _ht Here, He: Effective stack height Ho: Height of stack model △ _ht : Effective stack height He obtained from test gas rise height, and discharge from stack model The gas amount Q to be generated and the wind speed U in the wind tunnel are expressed by the following equation (3)

C (X) = [Q / {π · σ _y (X) · σ _z (X) · U}] exp
[−He ² / {2σ _z (X) ² }] Here, C (X): Surface concentration of the test gas on the ground model at the downwind distance X Q: Emission amount of the test gas U: Test wind speed in the wind tunnel He : Effective chimney height of the chimney model σ _y : Horizontal diffusion width of test gas σ _z : Vertical diffusion width of test gas to obtain the surface concentration C (X), and this surface concentration C (X)
Is the maximum surface concentration.

Further, in the method for estimating the maximum landing concentration according to the present invention, an arbitrary leeward distance X obtained based on the rising height of the test gas measured at a plurality of points in the x-axis direction in a state where the ground model is installed. Height of test gas with respect to
Substituting _t (X) into Equation 2 to obtain the effective chimney height He
Is given by the following [Equation 4], that is,

He = Ho + △ _ht (X) where, He: Effective chimney height of the chimney model Ho: Height of the chimney model _Δht (X): Height of the smoke axis for any leeward distance X Calculate according to

Further, in the method for estimating the maximum landing concentration according to the present invention, an arbitrary leeward distance X obtained based on the rising height of the test gas measured at a plurality of points in the x-axis direction in a state where the surface model is installed. Height of test gas with respect to
The leeward distance at the point where the graph showing _t (X) intersects with the straight line indicating the height of rise of the test gas on the flat plate used in the environmental assessment, _{に よ り} h _cal, is defined as X ₃ . The effective chimney height He
Is given by the following [Equation 5], that is,

He = Ho + △ h _t (X): X <X ₃ He = Ho + △ h _cal : X> X ₃ where, He: Effective chimney model chimney height Ho: Chimney model height Δh _t (X): Height of smoke axis rise for an arbitrary downwind distance X _{Δh cal} : Height of test gas obtained from the test gas height calculated on a flat plate used in environmental assessment.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 (1) shows the measurement limit leeward distance Xd in the wind tunnel experiments of FIGS. 1 (1) and 1 (2).
Horizontal diffusion widths sigma _yt of the test gas in the case where there is a surface thereof in the horizontal direction diffusion widths sigma _y of the test gas to the downwind distance X calculated based on density data of each downwind distance measured at a position below the distance FIG. 5 is a graph comparing the horizontal diffusion width σ _yf of the test gas with no surface object, and FIG.
(2) is the case where there is a surface object with respect to the vertical diffusion width σ _z of the test gas with respect to the leeward distance X obtained based on the concentration data for each leeward distance measured at a position less than the measurement limit leeward distance Xd. _Is a graph showing a comparison between the vertical diffusion width σ _zt of the test gas and the vertical diffusion width σ _zf of the test gas when there is no surface object, and FIG. 6 shows a distance less than the measurement leeward distance Xd in a conventional wind tunnel experiment. Height of the smoke axis with respect to the leeward distance X, which is obtained based on the density data for each leeward distance when there is a surface object measured at the position of △
graph showing changes in h _t, 7 was determined based on the density data for each downwind distance when there is a ground product which is measured at a distance of less than measurement limit downwind distance Xd in conventional wind tunnel experiments, downwind and changes in rise height △ h _t smoke axis with respect to the distance X, the graph showing a comparison between rising height △ h _cal determined by equation representing the rise height of the test gas in the flat plate used in the environmental assessment It is.

First, as shown in FIG. 5 (1), a wind tunnel experiment is performed within a range of a leeward distance equal to or less than the measurement limit leeward distance Xd according to a conventional wind tunnel experiment, and the wind tunnel experiment is performed in an upward direction in the presence of a surface object. Horizontal diffusion width σ _yt when there is a surface object calculated from the diffusion concentration of the test gas as discharged or released smoke, and when there is no surface object measured as the diffusion from the point source of the test gas on a flat plate Horizontal diffusion width σ
_Also described with _yf .

Similarly, as shown in FIG. 5 (2), the wind tunnel experiment is performed within the range of the leeward distance less than the measurement limit leeward distance Xd according to the conventional wind tunnel experiment, and the state where the surface object is present Vertical diffusion width σ _zt when there is a surface object calculated from the diffusion concentration of test gas as smoke exhausted or released in the upward direction, and surface object measured as diffusion from a point source of the test gas on a flat plate And the vertical diffusion width σ _zf when there is no

Next, as shown in FIG. 5A, the horizontal diffusion width _.sigma.yt and the terrestrial object when there is a terrestrial object at each leeward distance measured at a distance equal to or less than the measurement limit leeward distance Xd. Based on the horizontal diffusion width σ _yf without
Horizontal diffusion width σ of test gas for arbitrary downwind distance X
₅ is obtained as follows, and as shown in FIG. 5 (2), the vertical diffusion width σ when there is a surface object at each leeward distance measured at a position equal to or less than the measurement limit leeward distance Xd. _{Based on zt} and the vertical diffusion width σ _zf when there is no surface object, the vertical diffusion width σ _z of the test gas for an arbitrary leeward distance X is determined as follows.

As shown in FIG. 5A, a line passing through the horizontal diffusion width σ _yt of each measurement point when there is a surface object is approximated by a straight line and represented by σ _yt (X), and there is no surface object. A line passing through the horizontal diffusion width σ _yf of each measurement point in the case is approximated by a straight line and is represented by σ _yf (X). Further, as shown in FIG. 5 (2), a line passing through the vertical diffusion width σ _zt of each measurement point when there is a surface object is approximated by a straight line and represented by σ _zt (X). A line passing through the vertical diffusion width σ _zf of each measurement point is approximated by a straight line and represented by σ _zf (X).

Then, as shown in FIG. 5A, an approximate straight line σ _yt (X) passing through the horizontal diffusion width σ _yt of each measurement point when there is a surface object and each measurement when there is no surface object While the lee distance at the point where the approximate straight line σ _yf (X) passing through the horizontal diffusion width σ _yf of the point intersects is _defined as X ₁ , as shown in FIG. the approximate straight line sigma _zt through the vertical diffusion width σ _zt (X), an approximate straight line sigma _zf (X) and the downwind distance intersection through the vertical diffusion width sigma _zt of each measurement point in the case where there is no ground material X ₂ Then, the horizontal diffusion width σ _y (X) and the vertical diffusion width σ _z (X), which are affected by the surface object, are set as shown in Equation 1.

[0022]

## EQU1 ## σ _y (X) = σ _yt (X): X <X ₁ σ _y (X) = σ _yf (X): X> X ₁ σ _z (X) = σ _zt (X): X < X ₂ σ _z (X) = σ _zf (X): X> X ₂

[0023] This is because the disturbance of the flue gas or exhaust gas is considered to be the same as the disturbance of background downwind distant, X> in X ₁ horizontal diffusion width of the flue or exhaust gas sigma _y (X ) Is the horizontal diffusion width from the point source on the flat plate, i.e., the horizontal diffusion width when there is no surface _feature σ _yf
When X> X ₂ , the vertical diffusion width of smoke or exhaust gas σ _z (X) is the vertical diffusion width from a point source on a flat plate, that is, the vertical direction when there is no surface object This is assumed to be equal to the diffusion width σ _zf (X).

Using the expression [1], the surface density C (X) can be obtained by the expression [3].

C (X) = [Q / {π · σ _y (X) · σ _z (X) · U}] exp
[−He ² / {2σ _z (X) ² }] Here, C (X): Surface concentration of the test gas on the ground model at the downwind distance X Q: Emission amount of the test gas U: Test wind speed in the wind tunnel He : Effective chimney height of the chimney model, ie, the height of the chimney model and the rise height of the test gas from the chimney outlet σ _y (X): Horizontal diffusion width of the test gas σ _z (X): Vertical diffusion of the test gas width

Since the expression (3) represents the surface concentration of the exhaust gas or the test gas, the maximum landing concentration at which the surface concentration of the exhaust gas or the test gas becomes maximum can be obtained from the expression (3). .

FIG. 6 shows a conventional wind tunnel experiment.
The diffusion concentration of the exhaust gas emitted upward from the chimney model 3 in the state where the surface object is present, that is, the investigation gas, is measured, and the rising height {h of the smoke axis at each measurement point is indicated by a triangle mark}. It has also shown an approximate curve is approximated by a line passing through the elevated height △ h smoke axis △ h _t (X) at the point.

The height of the smoke axis 設置 h _t (X) with respect to an arbitrary leeward distance X obtained based on the height of the test gas measured at a plurality of points in the x-axis direction with the surface model installed is calculated. By substituting into the [Equation 2], the effective stack height H
e is expressed by the following [Equation 4], that is,

He = Ho + △ _ht (X) where, He: Effective chimney height of the chimney model Ho: Height of the chimney model _Δht (X): Height of the smoke axis for any leeward distance X It can be obtained by

In obtaining the maximum landing concentration at which the surface concentration of the exhaust gas or test gas becomes maximum from Expression 3, Expression 4 is substituted into Expression 3 to obtain the maximum value of C (X). By determining the value, the maximum landing concentration of the exhaust gas, that is, the test gas can be determined.

FIG. 7 shows a conventional wind tunnel experiment.
Based on the density data of each downwind distance X at each measurement point measured by the downwind distance measurement limit downwind distance Xd, together show the rise height △ h _t smoke axis about downwind distance X, in EIA In accordance with the method used, the height of rise of the smoke axis △ h _cal obtained by a calculation formula showing the height of rise of smoke exhaust on a flat plate is also shown.

In FIG. 7, in order to take into account the influence of surface objects, the height of the smoke axis at each measurement point {h} is indicated by a triangle in accordance with the conventional wind tunnel experiment.
An approximate curve Δh _t (X) approximated by a line passing through the height of elevation of the smoke axis Δh at each measurement point is also shown.

[0031] that is, FIG. 7, the surface thereof based on the diffusion concentration of the discharged or released test gas upwardly through a stack model 3 while there obtained smoke axis height of rise of △ h _t
And approximating the curve △ h _t (X), are shown together with increasing height △ h _cal smoke axis, calculated as increase the height of the flue gas on plates used in the environmental assessment.

Referring to FIG. 7, the rising height of the smoke axis with respect to an arbitrary leeward distance X obtained based on the rising height of the test gas measured at a plurality of points in the x-axis direction with the ground model installed. The leeward distance of the point where the graph indicating h _t (X) and the straight line indicating the rising height _{Δh cal} (X) obtained by a calculation formula representing the rising height of the test gas on the flat plate used in the environmental assessment intersect Is assumed to be X ₃ , the turbulence in the exhaust gas is considered to be the same as the turbulence in the background at a distant position in the leeward direction.

He = Ho + △ h _t (X): X <X ₃ He = Ho + △ h _cal (X): X> X ₃ where: He: Effective chimney model chimney height Ho: Chimney model height is △ h _t (X): increase of smoke shaft height to any downwind distance X △ h _cal (X): increase of the test gas obtained by increasing the height calculation formula of the test gas in the flat plate used in the environmental assessment It can be obtained by height.

In determining the maximum landing concentration at which the surface concentration of the exhaust gas or the test gas becomes maximum from Expression 3, Expression 5 is substituted into Expression 3 to obtain the maximum value of C (X). By determining the value, the maximum landing concentration of the exhaust gas, ie, the test gas, can be determined.

[0034]

According to the maximum landing density estimation method of the present invention, the following effects can be obtained. [1] A method for estimating the maximum landing concentration of an actual gas by setting a ground surface model in a wind tunnel, discharging a test gas from a chimney model in the wind tunnel, and performing a wind tunnel experiment, wherein the above-described test is performed. The origin of the coordinates is the discharge position of the gas from the chimney model, the x-axis in the leeward direction, the y-axis in the horizontal direction orthogonal to the x-axis, the z-axis in the vertical direction, and the distance in the x-axis direction from the origin. X and x without the above ground model
When there is no ground model of the test gas at an arbitrary downwind distance X obtained based on the horizontal diffusion width in the y-axis direction and the vertical diffusion width in the z-axis direction of the test gas measured at a plurality of points in the axial direction The horizontal diffusion width σ _yf (X) of the test gas and the vertical diffusion width σ _zf (X) _{without the} ground model, and the test gas measured at a plurality of points in the x-axis direction with the ground model installed Horizontal diffusion width σ of the test gas at an arbitrary leeward distance X obtained based on the diffusion width in the y-axis direction and the diffusion width in the z-axis direction when there is a ground model
_yt (X) and vertical diffusion width σ _zt when there is a ground model
(X) and a curve drawn by the horizontal diffusion width σ _yf (X) in the absence of the ground model at an arbitrary leeward distance X of the test gas and the horizontal diffusion width σ _{yt in the} presence of the ground model
The x-coordinate X _{1 of the} point where the curves drawn by (X) intersect with each other, the vertical diffusion width σ _zf (X) in the absence of the ground model at an arbitrary distance X of the test gas, and the _{presence of the} ground model And the x-coordinate X _{2 of the} point where the vertical diffusion width σ _zt (X) of

## EQU1 ## σ _y (X) = σ _yt (X): X <X ₁ σ _y (X) = σ _yf (X): X> X ₁ σ _z (X) = σ _zt (X): X < X ₂ σ _z (X) = σ _zf (X): The horizontal diffusion width σ _y (X) and the vertical diffusion width σ _z (X) of the test gas obtained by X> X ₂ and the above ground model Represents the height △ h _f (X) of rise of the test gas from the chimney model for an arbitrary distance X determined based on the height of rise of the test gas measured at a plurality of points in the x-axis direction without being installed. using increase the height △ h _t of the test gas in the case where there is the surface model in the curve with a predetermined straight line and the x-coordinate Xo of points intersect each other representing the height increases, the height Ho of the chimney model And [Equation 2], that is,

[Formula 2] He = Ho + △ h_t  Where: He: Effective stack height Ho: Height of the test gas release stack model △ h_t : Effective chimney height He obtained from the rising height of the test gas and emission from the chimney model
The amount of gas Q to be generated and the wind speed U in the wind tunnel are expressed by the following [Equation 3].
That is,

C (X) = [Q / {π · σ _y (X) · σ _z (X) · U}] exp
[−He ² / {2σ _z (X) ² }] Here, C (X): Surface concentration of the test gas on the ground model at the downwind distance X Q: Emission amount of the test gas U: Test wind speed in the wind tunnel He : Effective chimney height of the chimney model σ _y : Horizontal diffusion width of test gas σ _z : Vertical diffusion width of test gas to obtain the surface concentration C (X), and this surface concentration C (X)
Is determined as the maximum ground surface concentration, so even if it is not possible to investigate up to the leeward distance where the maximum concentration appears on the ground surface by a model experiment, the wind tunnel experiment within the measurement limit leeward distance Based on the experimental data obtained by the investigation, it is possible to estimate the maximum landing concentration occurring beyond the measurement limit downwind distance, which could not be investigated by the model experiment (Claim 1). [2] In the above maximum landing concentration estimation method, the test gas with respect to an arbitrary leeward distance X obtained based on the rise height of the test gas measured at a plurality of points in the x-axis direction in a state where the ground model is installed. By substituting the rising height △ _ht (X) into the _equation (2), the effective stack height He is calculated by the equation (4), that is,

He = Ho + △ _ht (X) where, He: Effective chimney height of the chimney model Ho: Height of the chimney model _Δht (X): Height of the smoke axis for any leeward distance X The maximum landing concentration, which was difficult to predict by wind tunnel experiments alone, was calculated by combining the experimental data obtained by a wind tunnel experiment within the measurement limit downwind distance with a calculation formula. It is possible to estimate the maximum landing density and the maximum landing density occurrence distance that occur beyond the measurement leeward distance that could not be investigated by a model experiment (Claim 2). [3] In the above maximum landing concentration estimation method, x
A graph showing the increase in height of any test gas to downwind distance X calculated based on the height of rise of the test gas, measured at a plurality of locations in the axial direction △ h _t (X), a flat plate used in the environmental assessment when the downwind distance increase was calculated expression representing the increasing height of the test gas height △ and line indicating the h _cal (X) intersects a point on the X _3, the effective chimney height the He, [ Equation 5], that is,

He = Ho + △ h _t (X): X <X ₃ He = Ho + △ h _cal (X): X> X ₃ where: He: Effective chimney model chimney height Ho: Chimney model height is △ h _t (X): increase of smoke shaft height to any downwind distance X △ h _cal (X): increase of the test gas obtained by increasing the height calculation formula of the test gas in the flat plate used in the environmental assessment The maximum landing density, which was difficult to predict only by wind tunnel experiments, was calculated by combining the experimental data obtained by a wind tunnel experiment within the measurement limit downwind distance with the calculation formula. The maximum landing concentration that occurs beyond the measurement downwind distance, which could not be investigated by the model experiment, and the maximum landing concentration occurrence distance can be estimated, and the calculation formula used in the environmental assessment is A highly accurate prediction of the maximum landing density can be performed by incorporating the influence of the surface object (claim 3).

[Brief description of the drawings]

FIG. 1 (1) is a longitudinal sectional view of a conventional wind tunnel test apparatus showing a situation in which a test gas is discharged from a chimney model in a wind tunnel to perform a wind tunnel test and to investigate an influence on a surface object, 2)
The figure is a graph showing the distribution of the landing concentration of the test gas in the leeward direction in the wind tunnel experiment of FIG.

FIG. 2A is a graph showing a change in a height of rise Δh of a test gas with respect to a distance X in a leeward direction. FIG. 2B is a graph showing the vertical diffusion width σ _z of the test gas at the distance X ′ in the leeward direction in FIG. 2A.

FIG. 3 is a graph showing a change in a height of rise of a test gas Δh with respect to a distance X in a leeward direction in a case where a surface object is present and a case where no surface object is present;

FIG. 4 shows the vertical diffusion width σ _zt of the test gas when there is a surface object and the vertical diffusion width σ _zp of the test gas when there is no surface object for the test gas released under the same conditions. It is a graph.

FIG. 5 (1) is a graph obtained based on density data at each leeward distance measured at a position less than the measurement limit leeward distance Xd in the wind tunnel experiments of FIGS. 1 (1) and 1 (2). for horizontal diffusion widths sigma _y of the test gas to the downwind distance X by comparing the horizontal diffusion widths sigma _yf of the test gas in the absence of the horizontal diffusion widths sigma _yt and surface of the test gas when there is a ground was FIG. 2B is a graph showing the vertical diffusion width σ of the test gas with respect to the leeward distance X obtained based on the concentration data at each leeward distance measured at a distance less than the measurement limit leeward distance Xd. it is a graph showing a comparison between vertical diffusion widths sigma _zf of the test gas in the absence of vertical diffusion widths sigma _zt and surface of the test gas in the case where there is a ground product for _z.

FIG. 6 shows a measurement leeward distance Xd in a conventional wind tunnel experiment.
Was determined on the basis of the density data of each downwind distance measured by the position of the following distance is a graph showing changes in rise height △ h _t smoke axis relative downwind distance X.

FIG. 7: Measurement limit downwind distance Xd in a conventional wind tunnel experiment
Was determined on the basis of the density data of each downwind distance measured by the position of the following distance, the change in height of rise △ h _t smoke axis relative downwind distance X, flue gas on a flat plate for use in environmental assessment 6 is a graph showing the height of smoke axis 煙 h _cal obtained by a calculation formula representing the height of rise of.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Uniform flow 2 Measurement room 3 Chimney model 4 Exhaust gas 5 Building model

Claims (3)

[Claims] 1. A method for estimating a maximum landing concentration of an actual gas in which a ground surface model is installed in a wind tunnel, a test gas is emitted from a chimney model in the wind tunnel, and a wind tunnel experiment is performed to predict an actual maximum landing concentration of gas. With the discharge position of the test gas from the chimney model as the origin of the coordinates, the x-axis in the leeward direction, the y-axis in the horizontal direction orthogonal to the x-axis, the z-axis in the vertical direction, and the x-axis direction from the origin Assuming that the distance is X, y of the test gas measured at a plurality of points in the x-axis direction without installing the ground model
The horizontal diffusion width σ _yf (X) and the ground model of the test gas at the arbitrary leeward distance X obtained based on the axial diffusion width in the axial direction and the vertical diffusion width in the z-axis direction without the surface model are Vertical diffusion width σ _zf (X) when there is no
The test gas at an arbitrary leeward distance X obtained based on the diffusion width in the y-axis direction and the diffusion width in the z-axis direction of the test gas measured at a plurality of points in the x-axis direction in a state where the ground model is installed. Horizontal diffusion width σ with a ground model
_yt (X) and vertical diffusion width σ _zt when there is a ground model
(X) and a curve drawn by the horizontal diffusion width σ _yf (X) in the absence of the ground model at an arbitrary leeward distance X of the test gas and the horizontal diffusion width σ _{yt in the} presence of the ground model
The x-coordinate X _{1 at the} point where the curve drawn by (X) intersects, the vertical diffusion width σ _zf (X) when the surface model is not present at an arbitrary distance X of the test gas, and the vertical direction when the surface model is present From the x coordinate X _{2 of the} point where the directional diffusion width σ _zt (X) intersects, the following equation (1), ie, σ _y (X) = σ _yt (X): X <X ₁ σ _y (X ) = Σ _yf (X): X> X ₁ σ _z (X) = σ _zt (X): X <X ₂ σ _z (X) = σ _zf (X): X> X _{2 The} above test gas Based on the horizontal diffusion width σ _y (X) and the vertical diffusion width σ _z (X) of the test gas measured at a plurality of points in the x-axis direction without the ground model. the surface model line and is in the x-coordinate Xo of points intersect each other to represent a rise height △ h _f (X) curve and a predetermined rise height representing a from the stack model of the test gas to the arbitrary distance X obtained Increase the height △ h _t of the test gas in cases, by using the height Ho of the chimney model, Equation 2 formula i.e., here Equation 2] _{He = Ho + △ h t,} He: Enabled Chimney height Ho: The height of the chimney model △ _ht : The effective chimney height He determined by the rising height of the test gas, the gas amount Q discharged from the chimney model, and the wind speed U in the wind tunnel, Equation 3], ie, C (X) = [Q / {π · σ _y (X) · σ _z (X) · U}] exp
[−He ² / {2σ _z (X) ² }] Here, C (X): Surface concentration of the test gas on the ground model at the downwind distance X Q: Emission amount of the test gas U: Test wind speed in the wind tunnel He : Effective chimney height of the chimney model σ _y : Horizontal diffusion width of the test gas σ _z : Vertical diffusion width of the test gas to obtain the surface concentration C (X), and this surface concentration C (X)
Method for estimating the maximum surface concentration using the maximum value of the maximum as the maximum surface concentration. 2. The method for estimating a maximum landing concentration according to claim 1, wherein an arbitrary value obtained based on a rising height of the test gas measured at a plurality of points in an x-axis direction in a state where the ground model is installed. Rise height of test gas with respect to leeward distance X △
h _t (X) is substituted into Equation 2 to obtain the effective chimney height H
e is _{expressed by the following equation} (4): He = Ho + △ h _t (X) where He: effective stack height of the chimney model Ho: height of the chimney model _Δht (X): arbitrary A method for estimating the maximum surface concentration, characterized in that it is obtained from the height of the smoke axis with respect to the leeward distance X of the ground. 3. The method for estimating a maximum landing concentration according to claim 1, wherein an arbitrary height determined based on a rising height of the test gas measured at a plurality of points in an x-axis direction in a state where the ground model is installed. Rise height of test gas with respect to leeward distance X △
The leeward distance of the point where the graph indicating h _t (X) and the straight line indicating the rising height _{Δh cal} (X) obtained by a calculation formula representing the rising height of the test gas on the flat plate used in the environmental assessment intersect When X is defined as X ₃ , the effective chimney height He is calculated by the following equation (5): He = Ho + △ h _t (X): X <X ₃ He = Ho + △ h _cal (X): X> X ₃ here, the He: effective chimney height of chimney model Ho: chimneys model height △ h _t (X): increase of smoke shaft height to any downwind distance X △ h _cal (X): environment A method for estimating the maximum surface concentration, characterized in that it is obtained from a test gas rise height obtained from a test gas rise height calculation formula on a flat plate used in the assessment.