CN103364439A - Method for determining object surface temperature under fog-comprising condition - Google Patents

Abstract

The invention discloses a method for determining object surface temperature under a fog-comprising condition. The method comprises the steps that: a fog-drop size distribution model and a fog-drop motion model are established; a heat transfer model of object surface under the fog-comprising condition is decomposed into a plurality of sub-models; a collision adsorption model of the fog-drops and the surface is established according to the fog-drop size distribution model and the motion model; an evaporation model of liquid film formed on the surface, a surface dew condensation model, a surface convection heat transfer model, a radiative heat transfer model between the surface and the atmosphere background, and a solar radiation model are established; object surface total heat flow is determined according to the object surface sub-models under the fog-comprising condition; and object surface temperature distribution is obtained according to an energy equation. According to the invention, the heat transfer model suitable for the object surface under a fog-comprising condition is established. Under a situation that external flow field is not calculated, the influences of external environments are converted into a plurality of reasonable and accurate boundary conditions. Therefore, object temperature field can be highly efficiently and rapidly calculated.

Description

A kind of method of determining to contain body surface temperature under the mist condition

Technical field

The invention belongs to a kind of modeling method of heat transfer model, be specifically related to determine the method for complicated weather condition body surface temperature.

Background technology

Nowadays, target detection, identification are the important channels of grasping the other side's target conditions, and wherein approach comprises radar, visible light, sound wave, infrared etc.Wherein, infrared have vital role at aspects such as infrared guidance, infrared monitorings.Therefore the infrared signature of grasping target is to infrared acquisition, identification, infrared stealth and anti-stealthyly all be significant.And the infrared signature of grasping target at first needs to calculate the temperature field of target.Document 1(declares the beneficial people, Han Yuge. the infrared signature of terrain object and background. Beijing: National Defense Industry Press, 2004,19-100) thermal model of terrain object under the sunny weather carried out modeling, and document 2(becomes the will tongued bell. the target property Modeling Calculation research of armored ground vehicle. and Institutes Of Technology Of Nanjing, 2012) further consider that the thermal interaction of armored ground vehicle and background set up the thermal model of the armored vehicle under the fine condition, can calculate the temperature field of target under fine condition.。

But weather condition changes unpredictably, and target may place under the different weather conditions, and such as weather such as greasy weather, open-air, rainy day, snow sky, dust and sand weather, frostings, the target surface diabatic process is different from fine condition.Take the greasy weather as example, the period appears at mist because sedimentation and the Air Flow effect of droplet, droplet is adsorbed in target surface with deposition, and evaporation can occur target surface deposition drop; In other period, if weather reaches certain condition, the dewfall coagulation also may occur in target surface; Above heat and mass transfer process certainly will affect the temperature field on surface, and then affects the thermal infrared characteristic of target.Document 1, document 2 described thermal models can not calculate and contain object temperature field under the greasy weather gas condition.

In addition, under natural environmental condition, in the object temperature distribution numerical evaluation, need usually to consider that object place environmental flow is on the impact in temperature field, this relates to the flow field and the temperature field coupling is calculated, its precision is higher, but need pay the long time cost, and counting yield is low.

Summary of the invention

The object of the present invention is to provide a kind of method of determining the body surface temperature under the mist condition that is applicable to contain.

The technical solution of the object of the invention is as follows: a kind of method of determining to contain body surface temperature under the mist condition may further comprise the steps:

Step 1, set up fog drop size distribution model and motion model; Described fog drop size distribution model and motion model are:

(a) the fog drop size distribution model is

n(r)＝ar ²exp(-br)

In the formula, a, b are water cut W and visibility V expression formula,

a＝9.781×10 ¹⁵V ^-6W ^-5

b＝1.304×10 ⁴V ^-1W ^-1

The pass of water cut W and visibility V is

Radiation fog W=0.00316V ^-1.54

Advection fog W=0.0156V ^-1.43

(b) the droplet motion model is

When r＜40 μ m, u ₀=2gr ²(ρ _Drop-ρ _Air)/9 μ _Air

When r 〉=40 μ m, $u_0=0.269\sqrt{2\mathrm{gr}({\mathrm{\ρ}}_{\mathrm{drop}}-{\mathrm{\ρ}}_{\mathrm{air}}){\mathrm{Re}}_0^{0.6}/{\mathrm{\ρ}}_{\mathrm{air}}}$

The average settlement speed of droplet

$\stackrel{\‾}{u_0}=-{\∫}_0^{\∞}{u}_0\left(r\right)n\left(r\right)\mathrm{dr}/{\∫}_0^{\∞}n\left(r\right)\mathrm{dr}$

The implication of parameter is in the formula: the droplet number in n (r) representation unit volume, the unit radius interval, and r is the droplet radius, and a, b are that W is the natural fog water cut about natural fog water cut W and visibility V expression formula, and V is mist visibility, u ₀The expression radius is the settling velocity of the droplet of r,

The average settlement speed of expression droplet, g is gravity constant, ρ _DropBe drop density, ρ _AirBe atmospheric density, μ _AirBe the dynamic viscosity coefficient of air, Re ₀Be the Reynolds number of the drop of r for radius.

Step 2, based on the heat transfer physical process that contains body surface under the mist condition, the heat transfer model that will contain body surface under the mist condition is decomposed into several submodels, and described submodel comprises: evaporation model, surface water that the collision Adsorption Model on droplet and surface, surface form liquid film reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background;

Step 3, set up the collision Adsorption Model on droplet and surface according to fog drop size distribution model and motion model; Described droplet with the collision Adsorption Model on surface is:

q _adsorb＝m _adsorbCp(T _air-T _s)

Wherein, m _AdsorbBe the surperficial droplet collision rate of adsorption,

$m_{\mathrm{adsorb}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{N}_i\·\frac{4}{3}{\mathrm{\ρ}}_{\mathrm{drop}}{\mathrm{\πr}}_i^3$

Wherein, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, only add up droplet weber number We less than or equal to 5 and radius be r _iThe drop number;

The weber number of droplet is: We=ρ _Dropd _Dropu _n ²/ σ _Drop

When We＜=5, think to be adsorbed on the surface after drop and wall bump; When 5 ﹤ We＜=10, think and rebound after the collision of drop and wall; When

The time, think drop be rebuffed after and the liquid film combination on the wall; When

The time, think that drop splashes to form unsettled coronary liquid film;

The implication of parameter is in the formula: q _AdsorbPresentation surface droplet collision absorption conductive heat flow, m _AdsorbThe presentation surface droplet collision rate of adsorption, Cp is the specific heat of drop, T _AirBe air themperature, T _sBe surface temperature, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, ρ _DropAnd σ _DropRepresent respectively drop density and surface tension, We represents the weber number of droplet, d _DropFor colliding the diameter of front drop, u _nNormal velocity during for droplet collision, μ _DropBe the dynamic viscosity coefficient of drop, Collision frequency for drop.

Step 4, the evaporation model of setting up surface formation liquid film, surface water reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background; Be respectively:

(a) surface forms the evaporation model of liquid film:

q _evap＝m _evap[h _fg+Cp(T _s-T _air)]

Wherein, m _EvapPresentation surface forms the evaporation rate of liquid film,

m _evap＝h _m(ρ _v,s-ρ _v,∞)

Regard the water in air steam as ideal gas, is then arranged

m _evap＝h _m·M _v/R(p _v,sat(T _s)/T _s-p _v,∞(T _∞)/T _∞)

Wherein, h _mThe mass transfer coefficient of expression liquid film evaporation,

h _m＝D _AB(2.0+0.6Re ^1/2Sc ^1/3)/L

Under the temperature t condition, the steam-laden pressure formula is

p _sat(t)＝400/3·exp[18.59-3991.11/(t+233.84)]

Temperature is that the soft air relative humidity of t is:

The implication of parameter is in the formula: q _EvapForm the evaporation and heat-exchange hot-fluid of liquid film for the surface, h _FgThe gasification latent heat of expression water, m _EvapPresentation surface forms the evaporation rate of liquid film, h _mThe mass transfer coefficient of expression liquid film evaporation, ρ _{V, s}Expression liquid film surface water vapour density, ρ _{V, ∞}Expression water in air vapour density, M _vBe the molal weight of water vapor, R is gas law constant, T _sBe wall place liquid film temperature, T _∞Be air themperature, p _{V, sat}Be T _sSaturation vapour pressure under the temperature, p _{V, ∞}Be T _∞Airborne steam partial pressure under the temperature, L are characteristic length, D _ABBe the coefficient of diffusion of water vapor to oxygen diffusion, Re is Reynolds number, and Sc is for executing close total,

Be soft air relative humidity, p _SatBe steam saturation pressure under the t temperature;

(b) surface water reveals the model that condenses:

q _cond＝m _cond[h _fg+Cp(T _air-T _s)]

Wherein, m _CondFor surface water reveals rate of setting,

m _cond＝7.985×10 ^-9(T _air-T _s) ^0.33(p _v,∞-p _v,sat)

The implication of parameter is in the formula: q _CondPresentation surface water reveals condensation heat transfer hot-fluid, m _CondFor surface water reveals rate of setting, p _{V, sat}Be saturation vapour pressure under the wall surface temperature, p _{V, ∞}Be airborne steam partial pressure; Under other weather conditions, reveal condensation condition as long as reach water, it is also applicable that surface water reveals the model that condenses.

(c) surperficial convection heat transfer model:

q _conv＝h(T _air-T _s)

Wherein, h is surperficial convection transfer rate,

h＝0.7331|T _s-T _air|+1.9u _air+1.8

The implication of parameter is in the formula: q _ConvBe surperficial convection heat transfer hot-fluid, h presentation surface convection transfer rate, u _AirBe wind speed;

(d) radiation heat exchange models between surface and the atmospheric background:

q _radiation＝α _skyq _sky-σε _sT _s ⁴

$q_{\mathrm{sky}}=\mathrm{\τ}\·{\mathrm{\σT}}_{\mathrm{air}}^4(a_0+b_0\sqrt{e_a\′})+{\mathrm{\ϵ}}_{\mathrm{fog}}{\mathrm{\σT}}_{\mathrm{fog}}^4$

The implication of parameter is in the formula: q _RadiationRadiation heat exchange hot-fluid between presentation surface and the atmospheric background, q _SkyThe radiation of expression atmospheric long wave, α _SkyPresentation surface is to the absorptivity of atmospheric long wave radiation, ε _sThe presentation surface emissivity, τ represents the mist layer to the transmitance of atmospheric long wave radiation, σ is Si Tepan-Boltzmann constant, a ₀, b ₀Be constant, 0.51＜a ₀＜0.61,0.059＜b ₀＜0.065, e _a' expression ground layer vapour pressure, ε _FogBe the emissivity of mist layer, T _FogExpression mist layer temperature;

(e) solar radiation model:

Sun scattered radiation is on the dip plane: $q_d=c_1*\sin h^{c_2}*\frac{1+\cos \mathrm{\β}}{2}$

Sun reflected radiation is on the dip plane: $q_r=c_1=\sin h^{c_2}*\mathrm{\ρ}*\frac{1-\cos \mathrm{\β}}{2}$

The implication of parameter is in the formula: q _dBe sun scattered radiation on the dip plane, q _rBe sun reflected radiation on the dip plane, β is the pitch angle, dip plane, c ₁, c ₂Be constant, as 50m≤mist visibility V＜100m, 400＜c ₁＜405; 100m≤mist visibility V＜300m, 465＜c ₁＜475; 300m≤mist visibility V＜500m, 540＜c ₁＜548; 500m≤mist visibility V＜800m, 670＜c ₁＜675; 1.05＜c ₂＜1.1, h is sun altitude, and ρ faces the reflectivity of solar radiation with being; Wherein, sun altitude h is obtained by local longitude and latitude, date, Time Calculation.Solar radiation model is considered droplet to the bridging effect of the direct radiation of solar radiation, so direct solar radiation is almost 0.

Step 5, according to the above-mentioned heat transfer sub-model that contains body surface under the mist condition, determine the total hot-fluid of body surface.Used formula is:

q _total＝q _conv+q _radiation+q _adsorb+q _evap+q _cond+α _sun(q _d+q _r)

The implication of parameter is in the formula: q _TotalBe the total hot-fluid of body surface, α _SunBe the absorptivity of surface to solar radiation.And then by the total hot-fluid of above body surface, try to achieve the body surface Temperature Distribution according to energy equation.

The present invention compared with prior art, its remarkable advantage is: 1) the present invention has set up the applicable body surface heat exchange models under the greasy weather gas that contains, and considers the influence of droplet, soft air surface temperature, can calculate the Temperature Distribution that contains body surface under the mist condition; 2) the present invention is in the situation that calculate extraneous flow field, with the impact of external environment be converted to several rationally, boundary condition more accurately, have efficiently, calculate fast the characteristics of object temperature field.

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

Description of drawings

Fig. 1 is foundation and the simplified flow chart that contains body surface heat exchange models under the mist condition.

Fig. 2 be on Dec 4th, 2011 0:00 to temperature, humidity temporal evolution figure between 14:30.

Fig. 3 be on Dec 4th, 2011 0:00 to wind speed temporal evolution figure between 14:30.

Fig. 4 is the calculated value temporal evolution figure of each centre of surface point temperature of steel plate.

Embodiment

In conjunction with Fig. 1, a kind of method of determining to contain body surface temperature under the mist condition may further comprise the steps:

Step 1, set up fog drop size distribution model and motion model; Described fog drop size distribution model and motion model are:

(a) the fog drop size distribution model is

n(r)＝ar ²exp(-br)

In the formula, a, b are water cut W and visibility V expression formula,

a＝9.781×10 ¹⁵V ^-6W ^-5

b＝1.304×10 ⁴V ^-1W ^-1

The pass of water cut W and visibility V is

Radiation fog W=0.00316V ^-1.54

Advection fog W=0.0156V ^-1.43

Calculate for radiation fog in the present embodiment.

(b) the droplet motion model is

When r＜40 μ m, u ₀=2gr ²(ρ _Drop-ρ _Air)/9 μ _Air

When r 〉=40 μ m, $u_0=0.269\sqrt{2\mathrm{gr}({\mathrm{\ρ}}_{\mathrm{drop}}-{\mathrm{\ρ}}_{\mathrm{air}}){\mathrm{Re}}_0^{0.6}/{\mathrm{\ρ}}_{\mathrm{air}}}$

The average settlement speed of droplet

$\stackrel{\‾}{u_0}=-{\∫}_0^{\∞}{u}_0\left(r\right)n\left(r\right)\mathrm{dr}/{\∫}_0^{\∞}n\left(r\right)\mathrm{dr}$

The implication of parameter is in the formula: the droplet number in n (r) representation unit volume, the unit radius interval, and r is the droplet radius, and a, b are that W is the natural fog water cut about natural fog water cut W and visibility V expression formula, and V is mist visibility, u ₀The expression radius is the settling velocity of the droplet of r,

The average settlement speed of expression droplet, g is gravity constant, ρ _DropBe drop density, ρ _AirBe atmospheric density, μ _AirBe the dynamic viscosity coefficient of air, Re ₀Be the Reynolds number of the drop of r for radius.

Step 2, based on the heat transfer physical process that contains body surface under the mist condition, the heat transfer model that will contain body surface under the mist condition is decomposed into several submodels, and described submodel comprises: evaporation model, surface water that the collision Adsorption Model on droplet and surface, surface form liquid film reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background;

Step 3, set up the collision Adsorption Model on droplet and surface according to fog drop size distribution model and motion model; Described droplet with the collision Adsorption Model on surface is:

q _adsorb＝m _adsorbCp(T _air-T _s)

Wherein, m _AdsorbBe the surperficial droplet collision rate of adsorption,

$m_{\mathrm{adsorb}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{N}_i\·\frac{4}{3}{\mathrm{\ρ}}_{\mathrm{drop}}{\mathrm{\πr}}_i^3$

Wherein, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, only add up droplet weber number We less than or equal to 5 and radius be r _iThe drop number;

The weber number of droplet is: We=ρ _Dropd _Dropu _n ²/ σ _Drop

When We＜=5, think to be adsorbed on the surface after drop and wall bump; When 5 ﹤ We＜=10, think and rebound after the collision of drop and wall; When The time, think drop be rebuffed after and the liquid film combination on the wall; When The time, think that drop splashes to form unsettled coronary liquid film;

The implication of parameter is in the formula: q _AdsorbPresentation surface droplet collision absorption conductive heat flow, m _AdsorbThe presentation surface droplet collision rate of adsorption, Cp is the specific heat of drop, T _AirBe air themperature, T _sBe surface temperature, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, ρ _DropAnd σ _DropRepresent respectively drop density and surface tension, We represents the weber number of droplet, d _DropFor colliding the diameter of front drop, u _nNormal velocity during for droplet collision, μ _DropBe the dynamic viscosity coefficient of drop,

Collision frequency for drop.

Step 4, the evaporation model of setting up surface formation liquid film, surface water reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background; Be respectively:

(a) surface forms the evaporation model of liquid film:

q _evap＝m _evap[h _fg+Cp(T _s-T _air)]

Wherein, m _EvapPresentation surface forms the evaporation rate of liquid film,

m _evap＝h _m(ρ _v,s-ρ _v,∞)

Regard the water in air steam as ideal gas, is then arranged

m _evap＝h _m·M _v/R(p _v,sat(T _s)/T _s-p _v,∞(T _∞)/T _∞)

Wherein, h _mThe mass transfer coefficient of expression liquid film evaporation,

h _m＝D _AB(2.0+0.6Re ^1/2Sc ^1/3)/L

Under the temperature t condition, the steam-laden pressure formula is

p _sat(t)＝400/3·exp[18.59-3991.11/(t+233.84)]

Temperature is that the soft air relative humidity of t is:

The implication of parameter is in the formula: q _EvapForm the evaporation and heat-exchange hot-fluid of liquid film for the surface, h _FgThe gasification latent heat of expression water, m _EvapPresentation surface forms the evaporation rate of liquid film, h _mThe mass transfer coefficient of expression liquid film evaporation, ρ _{V, s}Expression liquid film surface water vapour density, ρ _{V, ∞}Expression water in air vapour density, M _vBe the molal weight of water vapor, R is gas law constant, T _sBe wall place liquid film temperature, T _∞Be air themperature, p _{V, sat}Be T _sSaturation vapour pressure under the temperature, p _{V, ∞}Be T _∞Airborne steam partial pressure under the temperature, L are characteristic length, D _ABBe the coefficient of diffusion of water vapor to oxygen diffusion, Re is Reynolds number, and Sc is for executing close total,

Be soft air relative humidity, p _SatBe steam saturation pressure under the t temperature;

(b) surface water reveals the model that condenses:

q _cond＝m _cond[h _fg+Cp(T _air-T _s)]

Wherein, m _CondFor surface water reveals rate of setting,

m _cond＝7.985×10 ^-9(T _air-T _s) ^0.33(p _v,∞-p _v,sat)

The implication of parameter is in the formula: q _CondPresentation surface water reveals condensation heat transfer hot-fluid, m _CondFor surface water reveals rate of setting, p _{V, sat}Be saturation vapour pressure under the wall surface temperature, p _{V, ∞}Be airborne steam partial pressure; Under other weather conditions, reveal condensation condition as long as reach water, it is also applicable that surface water reveals the model that condenses.

(c) surperficial convection heat transfer model:

q _conv＝h(T _air-T _s)

Wherein, h is surperficial convection transfer rate,

h＝0.7331|T _s-T _air|+1.9u _air+1.8

The implication of parameter is in the formula: q _ConvBe surperficial convection heat transfer hot-fluid, h presentation surface convection transfer rate, u _AirBe wind speed;

(d) radiation heat exchange models between surface and the atmospheric background:

q _radiation＝α _skyq _sky-σε _sT _s ⁴

$q_{\mathrm{sky}}=\mathrm{\τ}\·{\mathrm{\σT}}_{\mathrm{air}}^4(a_0+b_0\sqrt{e_a\′})+{\mathrm{\ϵ}}_{\mathrm{fog}}{\mathrm{\σT}}_{\mathrm{fog}}^4$

The implication of parameter is in the formula: q _RadiationRadiation heat exchange hot-fluid between presentation surface and the atmospheric background, q _SkyThe radiation of expression atmospheric long wave, α _SkyPresentation surface is to the absorptivity of atmospheric long wave radiation, ε _sThe presentation surface emissivity, τ represents the mist layer to the transmitance of atmospheric long wave radiation, σ is Si Tepan-Boltzmann constant, a ₀, b ₀Be constant, 0.51＜a ₀＜0.61,0.059＜b ₀＜0.065, e _a' expression ground layer vapour pressure, ε _FogBe the emissivity of mist layer, T _FogExpression mist layer temperature; In the present embodiment, getting the mist layer thickness is 400m, and the mist time of occurrence is 6:00-8:00 in morning, and mist visibility V is 50m, ε _s=0.7, τ=0.001, a ₀=0.6, b ₀=0.06, ε _Fog=0.7;

(e) solar radiation model:

Sun scattered radiation is on the dip plane: $q_d=c_1*\sin h^{c_2}*\frac{1+\cos \mathrm{\β}}{2}$

Sun reflected radiation is on the dip plane: $q_r=c_1=\sin h^{c_2}*\mathrm{\ρ}*\frac{1-\cos \mathrm{\β}}{2}$

The implication of parameter is in the formula: q _dBe sun scattered radiation on the dip plane, q _rBe sun reflected radiation on the dip plane, β is the pitch angle, dip plane, c ₁, c ₂Be constant, as 50m≤mist visibility V＜100m, 400＜c ₁＜405; 100m≤mist visibility V＜300m, 465＜c ₁＜475; 300m≤mist visibility V＜500m, 540＜c ₁＜548; 500m≤mist visibility V＜800m, 670＜c ₁＜675; 1.05＜c ₂＜1.1, h is sun altitude, and ρ faces the reflectivity of solar radiation with being; Wherein, sun altitude h is obtained by local longitude and latitude, date, Time Calculation.Solar radiation model is considered droplet to the bridging effect of the direct radiation of solar radiation, so direct solar radiation is almost 0.In the present embodiment, at mist time of occurrence section 6:00-8:00, coefficient c ₁, c ₂By there being in January, 2013 greasy weather experimental data match to obtain.As 50m≤mist visibility V＜100m, c ₁=403.3; 100m≤mist visibility V＜300m, c ₁=470.5; 300m≤mist visibility V＜500m, c ₁=543.6; 500m≤mist visibility V＜800m, c ₁=672.2; c ₂=1.095.And in the fine period without mist, the Solar Tracing model that Ansys Fluent is pressed in solar radiation calculates.

Step 5, according to the above-mentioned heat transfer sub-model that contains body surface under the mist condition, determine the total hot-fluid of body surface.Used formula is:

q _total＝q _conv+q _radiation+q _adsorb+q _evap+q _cond+α _sun(q _d+q _r)

The implication of parameter is in the formula: q _TotalBe the total hot-fluid of body surface, α _SunBe the absorptivity of surface to solar radiation.And then by the total hot-fluid of above body surface, try to achieve the body surface Temperature Distribution according to energy equation.

In the present embodiment, locate weather parameters as design conditions take 32.89 ° of 117.36 ° of east longitudes between 0:00 to 4 day on the 4th Dec in 2011 14:30, north latitude, Fig. 2 is temperature, humidity temporal evolution figure, Fig. 3 is wind speed temporal evolution figure, mist approximately appears between the 6:00-8:00, suppose that this time period mist visibility is 50m, hot numerical analysis is carried out towards the steel plate of the 1m * 1m of the four corners of the world * 0.1m respectively in horizontal positioned and unsettled, side, and the calculated value temporal evolution figure of each centre of surface point temperature of steel plate as shown in Figure 4.

As from the foregoing, the present embodiment calculates under given weather condition for the steel plate of concrete size and has simulated each surperficial temperature variation of steel plate, considered that the period appears in mist, droplet, soft air are to the Heat Transfer Influence of surface of steel plate, can calculate the Temperature Distribution that contains body surface under the mist condition, external influence factor is transformed for several rational boundary conditions, and result of calculation is accurate.

Claims (5)

1. a method of determining to contain body surface temperature under the mist condition is characterized in that, may further comprise the steps:

Step 1, set up fog drop size distribution model and motion model;

Step 2, based on the heat transfer physical process that contains body surface under the mist condition, the heat transfer model that will contain body surface under the mist condition is decomposed into several submodels, and described submodel comprises: evaporation model, surface water that the collision Adsorption Model on droplet and surface, surface form liquid film reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background;

Step 3, set up the collision Adsorption Model on droplet and surface according to fog drop size distribution model and motion model;

Step 4, the evaporation model of setting up surface formation liquid film, surface water reveal condense radiation heat exchange models, solar radiation model between model, surperficial convection heat transfer model, surface and the atmospheric background;

Step 5, according to the above-mentioned heat transfer sub-model that contains body surface under the mist condition, determine the total hot-fluid of body surface, and then try to achieve the body surface Temperature Distribution according to energy equation.

2. the method for determining to contain body surface temperature under the mist condition according to claim 1 is characterized in that, the model of fog drop size distribution described in the step 1 and motion model are:

(a) the fog drop size distribution model is

n(r)＝ar ²exp(-br)

In the formula, a, b are water cut W and visibility V expression formula,

a＝9.781×10 ¹⁵V ^-6W ^-5

b＝1.304×10 ⁴V ^-1W ^-1

The pass of water cut W and visibility V is

Radiation fog W=0.00316V ^-1.54

Advection fog W=0.0156V ^-1.43

(b) the droplet motion model is

When r＜40 μ m, u ₀=2gr ²(ρ _Drop-ρ _Air)/9 μ _Air

When r 〉=40 μ m, $u_0=0.269\sqrt{2\mathrm{gr}({\mathrm{\ρ}}_{\mathrm{drop}}-{\mathrm{\ρ}}_{\mathrm{air}}){\mathrm{Re}}_0^{0.6}/{\mathrm{\ρ}}_{\mathrm{air}}}$

The average settlement speed of droplet

$\stackrel{\‾}{u_0}=-{\∫}_0^{\∞}{u}_0\left(r\right)n\left(r\right)\mathrm{dr}/{\∫}_0^{\∞}n\left(r\right)\mathrm{dr}$

The implication of parameter is in the formula: the droplet number in n (r) representation unit volume, the unit radius interval, and r is the droplet radius, and a, b are that W is the natural fog water cut about natural fog water cut W and visibility V expression formula, and V is mist visibility, u ₀The expression radius is the settling velocity of the droplet of r,

The average settlement speed of expression droplet, g is gravity constant, ρ _DropBe drop density, ρ _AirBe atmospheric density, μ _AirBe the dynamic viscosity coefficient of air, Re ₀Be the Reynolds number of the drop of r for radius.

3. the method for determining to contain body surface temperature under the mist condition according to claim 1 is characterized in that, droplet described in the step 3 with the collision Adsorption Model on surface is:

q _adsorb＝m _adsorbCp(T _air-T _s)

Wherein, m _AdsorbBe the surperficial droplet collision rate of adsorption,

$m_{\mathrm{adsorb}}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{N}_i\·\frac{4}{3}{\mathrm{\ρ}}_{\mathrm{drop}}{\mathrm{\πr}}_i^3$

Wherein, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, only add up droplet weber number We less than or equal to 5 and radius be r _iThe drop number;

The weber number of droplet is: We=ρ _Dropd _Dropu _n ²/ σ _Drop

When We＜=5, think to be adsorbed on the surface after drop and wall bump; When 5 ﹤ We＜=10, think and rebound after the collision of drop and wall; When

The time, think drop be rebuffed after and the liquid film combination on the wall; When

The time, think that drop splashes to form unsettled coronary liquid film;

The implication of parameter is in the formula: q _AdsorbPresentation surface droplet collision absorption conductive heat flow, m _AdsorbThe presentation surface droplet collision rate of adsorption, Cp is the specific heat of drop, T _AirBe air themperature, T _sBe surface temperature, N _iRepresentation unit time inside radius is r _iThe collision absorption number of drop, ρ _DropAnd σ _DropRepresent respectively drop density and surface tension, We represents the weber number of droplet, d _DropFor colliding the diameter of front drop, u _nNormal velocity during for droplet collision, μ _DropBe the dynamic viscosity coefficient of drop,

Collision frequency for drop.

4. the method for determining to contain body surface temperature under the mist condition according to claim 1, it is characterized in that, evaporation model, the surface water that the surface forms liquid film in the step 4 reveals and condenses that radiation heat exchange models, solar radiation model are respectively between model, surperficial convection heat transfer model, surface and the atmospheric background:

(a) surface forms the evaporation model of liquid film:

q _evap＝m _evap[h _fg+Cp(T _s-T _air)]

Wherein, m _EvapPresentation surface forms the evaporation rate of liquid film,

m _evap＝h _m(ρ _v,s-ρ _v,∞)

Regard the water in air steam as ideal gas, is then arranged

m _evap＝h _m·M _v/R·(p _v,sat(T _s)/T _s-p _v,∞(T _∞)/T _∞)

Wherein, h _mThe mass transfer coefficient of expression liquid film evaporation,

h _m＝D _AB(2.0+0.6Re ^1/2Sc ^1/3)/L

Under the temperature t condition, the steam-laden pressure formula is

p _sat(t)＝400/3·exp[18.59-3991.11/(t+233.84)]

Temperature is that the soft air relative humidity of t is:

The implication of parameter is in the formula: q _EvapForm the evaporation and heat-exchange hot-fluid of liquid film for the surface, m _EvapPresentation surface forms the evaporation rate of liquid film, h _FgThe gasification latent heat of expression water, h _mThe mass transfer coefficient of expression liquid film evaporation, ρ _{V, s}Expression liquid film surface water vapour density, ρ _{V, ∞}Expression water in air vapour density, M _vBe the molal weight of water vapor, R is gas law constant, T _sBe wall place liquid film temperature, T _∞Be air themperature, p _{V, sat}Be T _sSaturation vapour pressure under the temperature, p _{V, ∞}Be T _∞Airborne steam partial pressure under the temperature, L are characteristic length, D _ABBe the coefficient of diffusion of water vapor to oxygen diffusion, Re is Reynolds number, and Sc is for executing close total,

Be soft air relative humidity, p _SatBe steam saturation pressure under the t temperature;

(b) surface water reveals the model that condenses:

q _cond＝m _cond[h _fg+Cp(T _air-T _s)]

Wherein, m _CondFor surface water reveals rate of setting,

m _cond＝7.985×10 ^-9(T _air-T _s) ^0.33(p _v,∞-p _v,sat)

The implication of parameter is in the formula: q _CondPresentation surface water reveals condensation heat transfer hot-fluid, m _CondFor surface water reveals rate of setting, p _{V, sat}Be saturation vapour pressure under the wall surface temperature, p _{V, ∞}Be airborne steam partial pressure;

(c) surperficial convection heat transfer model:

q _conv＝h(T _air-T _s)

Wherein, h is surperficial convection transfer rate,

h＝0.7331|T _s-T _air|+1.9u _air+1.8

The implication of parameter is in the formula: q _ConvBe surperficial convection heat transfer hot-fluid, h presentation surface convection transfer rate, u _AirBe wind speed;

(d) radiation heat exchange models between surface and the atmospheric background:

q _radiation＝α _skyq _sky-σε _sT _s ⁴

$q_{\mathrm{sky}}=\mathrm{\τ}\·{\mathrm{\σT}}_{\mathrm{air}}^4(a_0+b_0\sqrt{e_a\′})+{\mathrm{\ϵ}}_{\mathrm{fog}}{\mathrm{\σT}}_{\mathrm{fog}}^4$

The implication of parameter is in the formula: q _RadiationRadiation heat exchange hot-fluid between presentation surface and the atmospheric background, q _SkyThe radiation of expression atmospheric long wave, α _SkyPresentation surface is to the absorptivity of atmospheric long wave radiation, ε _sThe presentation surface emissivity, τ represents the mist layer to the transmitance of atmospheric long wave radiation, σ is Si Tepan-Boltzmann constant, a ₀, b ₀Be constant, 0.51＜a ₀＜0.61,0.059＜b ₀＜0.065, e _a' expression ground layer vapour pressure, ε _FogBe the emissivity of mist layer, T _FogExpression mist layer temperature;

(e) solar radiation model:

Sun scattered radiation is on the dip plane: $q_d=c_1*\sin h^{c_2}*\frac{1+\cos \mathrm{\β}}{2}$

Sun reflected radiation is on the dip plane: $q_r=c_1=\sin h^{c_2}*\mathrm{\ρ}*\frac{1-\cos \mathrm{\β}}{2}$

The implication of parameter is in the formula: q _dBe sun scattered radiation on the dip plane, q _rBe sun reflected radiation on the dip plane, β is the pitch angle, dip plane, c ₁, c ₂Be constant, as 50m≤mist visibility V＜100m, 400＜c ₁＜405; 100m≤mist visibility V＜300m, 465＜c ₁＜475; 300m≤mist visibility V＜500m, 540＜c ₁＜548; 500m≤mist visibility V＜800m, 670＜c ₁＜675; 1.05＜c ₂＜1.1, h is sun altitude, and ρ faces the reflectivity of solar radiation with being; Wherein, sun altitude h is obtained by local longitude and latitude, date, Time Calculation.

5. the method for determining to contain body surface temperature under the mist condition according to claim 1 is characterized in that, step 5 determines that the used formula of the total hot-fluid of body surface is:

q _total＝q _conv+q _radiation+q _adsorb+q _evap+q _cond+α _sun(q _d+q _r)

The implication of parameter is in the formula: q _TotalBe the total hot-fluid of body surface, α _SunBe the absorptivity of surface to solar radiation.

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