CN104461680A - Fully mechanized caving face dust motion track numerical modeling method - Google Patents

Abstract

The invention belongs to the technical field of working face dust motion track research in production, and relates to a fully mechanized caving face dust motion track numerical modeling method. Firstly, a velocity distribution formula of a fully mechanized caving face viscous bottom layer region is deduced according to a viscous bottom layer region velocity distribution rule in hydromechanics and a Nikuradse experiment empirical formula; secondly, flow states of air flow is judged according to the average velocity value of fully mechanized caving face inlet section air flow, and a fully mechanized caving face inlet section air velocity self-defined function is programmed by means of the C language according to different flow states; finally, the fully mechanized caving face inlet section air velocity self-defined function is explained in FLUENT software and is set to be a boundary condition of fully mechanized caving face inlet section air velocity; EDEM software and the FLUENT software are mutually coupled, dust particle coordinate data are derived to obtain fitting functions of motion tracks of dust with different particle sizes, and accordingly the motion tracks of the dust with different particle sizes on the fully mechanized caving face are obtained through simulation. The method is easy and convenient to implement, principles are reliable, design is scientific, and the data are precise.

Description

A kind of method for numerical simulation of fully mechanized coal face dust movement track

Technical field:

The invention belongs to production field workplace dust movement track studying technological domain, being specifically related to a kind of method for numerical simulation for studying fully mechanized coal face different-grain diameter dust movement track.

Background technology:

Comprehensive mechanization caving coal mining workplace is called for short fully mechanized coal face, its dust produced in process of production drastically influence the healthy of workman and life safety, so take the measure of reasonable science extremely important to reduce dust concentration in practice, and the movement locus of clear and definite dust is the key factor taking measures to reduce dust concentration, but, current theoretical circles concentrate on dust migration rule mostly to the numerical simulation study of dust, and very few to the research of different-grain diameter dust movement track.Therefore a kind of novel method for numerical simulation for fully mechanized coal face different-grain diameter dust movement track of research and design of the present invention, has important more practical value and application prospect.

The wind speed profile of fully mechanized coal face affects distinguished and admirable distribution, varying in size of wind speed, and distinguished and admirable flow state is also different, and the distribution situation of sectional wind velocity also changes to some extent, and the flow state of fluid is divided into laminar flow and turbulent flow two kinds of fluidised forms according to the difference of Reynolds number; For circular pipe, when the flow state of fluid is laminar flow, the wind velocity distribution of pipe section is the paraboloid of revolution; When the flow state of fluid is turbulent flow, because its flow mechanism is different from laminar flow, its velocity distribution and laminar flow have basic difference, in the most of region near tubular axis, the transverse direction pulsation of fluid particle makes the momentum-exchange of carrying out between fluid layer comparatively strong, and this region becomes turbulent core district; Be close to wall place due to the laminar flow thin layer disappeared of pulsing because of wall restriction, viscous force between fluid layer makes flow velocity sharply decline, velocity gradient is larger, this thin layer is called viscous sublayer, tests the velocity distribution function in known circular pipe section viscous sublayer and turbulent core district according to prandtl hypothesis and Ni Gulazi.

Fully mechanized coal face is non-circular section, early fifties BH Wo Luoning (Soviet Union mine ventilation scholar) has delivered about the wind speed profile function on workplace xsect, within 1977, Northeast Polytechnic College ventilation safety teaching and research room have modified the formula of BH Wo Luoning derivation on experimental study basis, nineteen eighty-two and the workplace wind speed profile function of having derived different from the formula that BH Wo Luoning derives theoretically towards song (Beijing College of Iron and Steel Technology professor), within more than 1989, leap on the basis of above research, analyze the defect of above formula, and the L Prandtl formula of workplace wind speed profile is proposed according to prandtl hypothesis, the calculating of the distinguished and admirable wind speed of viscous sublayer and turbulent core district is integrated by the formula of above-mentioned research, but accurately can not reflect workplace viscous sublayer district distribution of air flow situation, the non-circular workplace viscous sublayer district wind speed formula of research and design of the present invention is effectively supplementing non-circular workplace wind speed profile, and method for numerical simulation based on this can react the actual conditions of fully mechanized coal face conscientiously.

Summary of the invention:

The object of the invention is to the defect overcoming prior art existence, seek to design the method for numerical simulation that a kind of fully mechanized coal face dust movement track is provided, the movement locus that analog computation goes out different-grain diameter dust can be specified, thus take measurements for reduction targetedly.

To achieve these goals, the method for numerical simulation that the present invention relates to specifically comprises following processing step:

(1) according to fluid mechanics viscous sublayer district's flowing law and Buddhist nun La Zi experiment experience formula, in conjunction with the central point of fully mechanized coal face, derive and show that fully mechanized coal face inlet section viscous sublayer district wind speed computing formula is:

$v_x=\stackrel{\‾}{v}\sqrt{2(1-\frac{r}{r_0})}---\left(7\right)$

Wherein, v _x---fully mechanized coal face inlet section viscous sublayer district wind speed, v _x>=0, unit m/s; ---fully mechanized coal face inlet section mean wind speed, unit m/s; R---arbitrfary point, fully mechanized coal face inlet section viscous sublayer district (A) to the distance of fully mechanized coal face central point, unit m; r ₀---fully mechanized coal face central point to workplace border vertical range and through arbitrfary point, fully mechanized coal face inlet section viscous sublayer district (A), r ₀>=r, unit m.

(2) distinguished and admirable according to fully mechanized coal face inlet section average speed value calculates Reynolds number, to judge distinguished and admirable fluidised form:

If 1. Reynolds number is less than 2000, be Laminar Flow, so according to the wind speed formula (7) in fully mechanized coal face inlet section viscous sublayer district, adopt conventional computer C language to write fully mechanized coal face inlet section wind speed self-defining function;

$v_x=\stackrel{\‾}{v}\sqrt{2(1-\frac{r}{r_0})}---\left(7\right)$

If 2. Reynolds number is greater than 2000, it is Turbulence Flow, the wind speed formula (7) in so comprehensive fully mechanized coal face inlet section viscous sublayer district and non-circular workplace turbulent region wind speed profile formula (8), adopt conventional computer C language to write fully mechanized coal face inlet section wind speed self-defining function;

$v_x=\stackrel{\‾}{v}[1+3.17\sqrt{\mathrm{\α}}+2.28\sqrt{\mathrm{\α}}\ln (1-\frac{r}{r_0})]---\left(8\right)$

Wherein, v _x---fully mechanized coal face turbulent region wind speed, v _x> 0, unit m/s; ---fully mechanized coal face inlet section mean wind speed, unit m/s; R---arbitrfary point, fully mechanized coal face turbulent region (A) to the distance of fully mechanized coal face central point, unit m; r ₀---fully mechanized coal face central point to workplace border vertical range and through arbitrfary point, fully mechanized coal face turbulent region (A), r ₀> r, unit m;

(3) fully mechanized coal face inlet section wind speed self-defining function is made an explanation in fluid analysis software FLUENT, and be arranged to the boundary condition of fully mechanized coal face inlet section wind speed; Then grain size analysis software EDEM and fluid analysis software FLUENT is intercoupled, and derive dust granules coordinate data to obtain the fitting function of different-grain diameter dust movement track, thus simulation draws the movement locus of fully mechanized coal face different-grain diameter dust.

The present invention compared with prior art, EDEM software is coupled with FLUENT software can simulate the Multiphase Flow of particle scale, this coupling enhances the ability of FLUENT software simulation polyphasic flow, can comprise the feature as particles such as distribution of particles, particle habit, geometric attribute and surface forces, above-mentioned polyphasic flow attribute all has obvious impact to particle and fluid; The method realizes easy, and principle is reliable, design science, and data are accurate, with low cost.

Accompanying drawing illustrates:

Fig. 1 is the process flow diagram of the method for numerical simulation that the present invention relates to.

Fig. 2 is that the EDEM software coupling that the present invention relates to calculates interface schematic diagram.

Fig. 3 is that the FLUENT software coupling that the present invention relates to calculates interface schematic diagram.

Fig. 4 is 1 × 10 for the present invention is directed to particle diameter in fully mechanized coal face ³the movement locus numerical simulation schematic diagram of μm dust.

Fig. 5 is 1.6 × 10 for the present invention is directed to particle diameter in fully mechanized coal face ²the movement locus numerical simulation schematic diagram of μm dust.

Fig. 6 is 1.0 × 10 for the present invention is directed to particle diameter in fully mechanized coal face ²the movement locus numerical simulation schematic diagram of μm dust.

Fig. 7 the present invention is directed to the movement locus numerical simulation schematic diagram that particle diameter in fully mechanized coal face is 50 μm of dust.

Fig. 8 the present invention is directed to the movement locus numerical simulation schematic diagram that particle diameter in fully mechanized coal face is 8 μm of dust.

Embodiment:

By embodiment, further description is made to the present invention below in conjunction with accompanying drawing.

Embodiment:

The method for numerical simulation of the fully mechanized coal face dust movement track that the present embodiment relates to comprises the following steps:

(1) derivation fully mechanized coal face inlet section viscous sublayer district wind speed computing formula:

According to fluid mechanics viscous sublayer district's flowing law and Buddhist nun La Zi experiment experience formula, in conjunction with the central point of fully mechanized coal face, derive and draw fully mechanized coal face inlet section viscous sublayer district wind speed computing formula.

Lineal layout is thought by approximate for the velocity distribution of wind speed, that is: in fully mechanized coal face inlet section viscous sublayer district (being called for short viscous sublayer district)

$\frac{{\mathrm{dv}}_x}{\mathrm{dy}}=\frac{v_x}{y}---\left(1\right)$

In formula, ---velocity gradient;

V _x---viscous sublayer district random spot speed, unit m/s, v _x>=0;

Y---arbitrfary point, viscous sublayer district to the vertical range on workplace border, unit m, y >=0;

By stress approximate representation be:

$\mathrm{\τ}=\mathrm{\μ}\frac{v_x}{y},y\≤\mathrm{\δ}---\left(2\right)$

In formula, δ---the thickness in viscous sublayer district, unit m;

τ---viscous shearing stress, unit N/m ²;

μ---viscosity, unit Pas.

Can be obtained by formula (2):

$v_x=v_{*}^2\frac{y}{\mathrm{\ν}}---\left(3\right)$

In formula, v _*---resistance speed, unit m/s;

ν---kinematic viscosity, unit m ²/ s.

Order

$v_{*}=\sqrt{\frac{\mathrm{\τ}}{\mathrm{\ρ}}}---\left(4\right)$

In formula, the density of ρ---air, unit K g/m ³.

Formula (4) is derived according to Bernoulli equation and Darcy's law and is drawn following formula:

$v_{*}=\stackrel{\‾}{v}\sqrt{\frac{\mathrm{\λ}}{8}}=\stackrel{\‾}{v}\frac{\sqrt{\mathrm{\α}}}{\sqrt{\mathrm{\ρ}}}---\left(5\right)$

In formula, λ---Darcy coefficient, zero dimension;

α---coefficient of frictional resistance, units/kg/m ³;

Learn according to Ni Gulazi experiment and meet following formula at laminar region λ:

$\mathrm{\λ}=\frac{64}{R_e}=\frac{64\mathrm{\ν}}{v_{x}d}---\left(6\right)$

In formula, d---equivalent diameter, unit m;

R _e---Reynolds number, zero dimension.

Formula (5), (6) are substituted into formula (3), uses after arranging r/r ₀the wind speed formula in the fully mechanized coal face inlet section viscous sublayer district represented is as follows:

$v_x=\stackrel{\‾}{v}\sqrt{2(1-\frac{r}{r_0})}---\left(7\right)$

In formula, v _x---fully mechanized coal face inlet section viscous sublayer district wind speed, v _x>=0, unit m/s; ---fully mechanized coal face inlet section mean wind speed, unit m/s; R---arbitrfary point, viscous sublayer district (A) to the distance of fully mechanized coal face central point, unit m; r ₀---fully mechanized coal face central point to workplace border vertical range and through arbitrfary point, viscous sublayer district (A), r ₀>=r, unit m.

(2) write fully mechanized coal face inlet section wind speed self-defining function: for fully mechanized coal face in reality, calculate Reynolds number with the distinguished and admirable fluidised form of interpretation by the average velocity that fully mechanized coal face inlet section is distinguished and admirable:

If 1. Reynolds number is less than 2000, be Laminar Flow, according to the wind speed formula (7) in fully mechanized coal face inlet section viscous sublayer district, adopt C-language Programming Design to write fully mechanized coal face inlet section wind speed self-defining function;

$v_x=\stackrel{\‾}{v}\sqrt{2(1-\frac{r}{r_0})}---\left(7\right)$

If 2. Reynolds number is greater than 2000, it is Turbulence Flow, the wind speed formula (7) in comprehensive fully mechanized coal face inlet section viscous sublayer district and non-circular workplace turbulent region wind speed profile formula (8), adopt C-language Programming Design to write fully mechanized coal face inlet section wind speed self-defining function;

$v_x=\stackrel{\‾}{v}[1+3.17\sqrt{\mathrm{\α}}+2.28\sqrt{\mathrm{\α}}\ln (1-\frac{r}{r_0})]---\left(8\right)$

In formula, v _x---fully mechanized coal face turbulent region wind speed, v _x> 0, unit m/s;

---fully mechanized coal face inlet section mean wind speed, unit m/s;

R---arbitrfary point, fully mechanized coal face turbulent region (A) to the distance of fully mechanized coal face central point, unit m;

R ₀---fully mechanized coal face central point to workplace border vertical range and through arbitrfary point, fully mechanized coal face turbulent region (A), r ₀> r, unit m.

Described writing of fully mechanized coal face inlet section wind speed self-defining function with operating procedure is:

1. fully mechanized coal face inlet section wind speed self-defining function write step

User-Defined Functions header file;

Fully mechanized coal face inlet section wind speed self-defining function DEFINE_PROFILE;

Variable (comprising array variable x [ND_ND], coordinate variable a, b, face data variable face_t f) is set;

Loop statement begin_f_loop (f, thread), to be used for scanning in whole workplace region all;

Function F _ CENTROID (x, f, thread), obtains the barycenter in each face, and the coordinate figure assignment of barycenter to x;

Assignment a=x [0] is carried out to coordinate variable, b=x [1];

Use if, else statement, according to the different situations of coordinate, fully mechanized coal face inlet section air current state is different, gives corresponding computing formula to F_PROFILE (f, thread, position);

End loop statement f_loop (f, thread)

2. the operating procedure of fully mechanized coal face inlet section wind speed self-defining function

In FLUENT software, click menu define-user defined – function – interpreted;

In the dialog box interpreted UDFs ejected, click Browse ..., the fully mechanized coal face User-Defined Functions of writing is imported;

Button click interprete.

Certain colliery 3 is chosen as with the geometric model of fully mechanized coal face in the present embodiment _on1110 fully mechanized coal faces are that example is described, according to 3 _onthe on-the-spot actual measurement of 1110 fully mechanized coal faces, the pre-processing software GAMBIT adopting FLUENT software to carry sets up physical model, is respectively by the length of model and is set as 20.0m, 10.0m, 3.0m;

First, in the present embodiment 3 _onthe distinguished and admirable fluidised form of 1110 fully mechanized coal faces differentiates, when fully mechanized coal face inlet section mean wind speed is 2m/s, calculates Reynolds number:

$\mathrm{Re}=\frac{\mathrm{vd}}{\mathrm{\ν}}=\frac{2\·4S/C}{\mathrm{\ν}}=\frac{2\·4\·30/26}{14.8\·{10}^{-6}}=623700---\left(9\right)$

In formula, the area of S---fully mechanized coal face, unit m ²;

The girth of C---fully mechanized coal face, unit m.

Be greater than 2000 by formula (9) known Reynolds number, then the flow state of fully mechanized coal face is Turbulence Flow.

Secondly, according to wind speed formula (7), non-circular workplace turbulent region wind speed profile formula (8) and 3 in fully mechanized coal face inlet section viscous sublayer district _onthe actual conditions of 1110 fully mechanized coal faces, adopt C language to write fully mechanized coal face inlet section wind speed self-defining function udfvelocity_inlet, specific code is as follows:

(3) numerical simulation movement locus: above-mentioned fully mechanized coal face inlet section wind speed self-defining function udf velocity_inlet is made an explanation in fluid analysis software FLUENT, and is arranged to the boundary condition of fully mechanized coal face inlet section wind speed; Then grain size analysis software EDEM and fluid analysis software FLUENT is intercoupled, and derive dust granules coordinate data to obtain the fitting function of different-grain diameter dust movement track, thus simulation draws the movement locus of fully mechanized coal face different-grain diameter dust, concrete numerical simulation is as follows:

1. grain size analysis software EDEM is coupled after installing with fluid analysis software FLUENT, fully mechanized coal face grid model file is imported in fluid analysis software FLUENT, then computation model, discrete type parameter, boundary condition and sources of particles major parameter are set, and solve parameter;

2. in grain size analysis software EDEM, fully mechanized coal face grid model file is imported, then set environment parameter, solid, the parameter of the dust such as particle diameter, material, quantity, calculating parameter;

3. in fluid analysis software FLUENT, open the EDEM-uncoupled module under Models, the coupling process of EDEM and FLUENT is set wherein, and EDEM file is called in;

4. particle diameter is set in grain size analysis software EDEM and (comprises 1 × 10 ³um, 1.6 × 10 ²um, 1.0 × 10 ²um, 50um, 8um), each particles number is respectively 100, when the computing time that is coupled is 0.3579s, the movement locus of each particle diameter dust as Figure 4-8, less by the known dust size of accompanying drawing content, the identical time is larger to the scope of outlet diffusion, less with z-axis negative direction angle.

The fluid analysis software FLUENT related in the present embodiment is CFD software package general at present, can be used for simulating the Complex Flows be never compressible in highly compressible scope, it includes front processor, solver and preprocessor, all can download in domestic each fatware websites such as software download center, the Pacific Ocean and 121 download websites; Involved grain size analysis software EDEM is the general CAE software being used for Simulation and analysis particle disposal and production operation of a modernization discrete element analysis tech design; it is the flagship product of DEM-Solutions company of Britain, and Beijing sea base technology & development Co. is EDEM China Software commission merchant.

Claims (1)

1. a method for numerical simulation for fully mechanized coal face dust movement track, is characterized in that specifically comprising the following steps:

(1) according to fluid mechanics viscous sublayer district's flowing law and Buddhist nun La Zi experiment experience formula, in conjunction with the central point of fully mechanized coal face, derive and show that fully mechanized coal face inlet section viscous sublayer district wind speed computing formula is:

$v_x=\stackrel{\‾}{v}\sqrt{2(1-\frac{r}{r_0})}$

Wherein, v _xfor fully mechanized coal face inlet section viscous sublayer district wind speed, v _x>=0, unit m/s; for fully mechanized coal face inlet section mean wind speed, unit m/s; R is the distance of arbitrfary point, fully mechanized coal face inlet section viscous sublayer district (A) to fully mechanized coal face central point, unit m; r ₀for fully mechanized coal face central point is to the vertical range on workplace border and through arbitrfary point, fully mechanized coal face inlet section viscous sublayer district (A), r ₀>=r, unit m;

(2) distinguished and admirable according to fully mechanized coal face inlet section average speed value calculates Reynolds number, to judge distinguished and admirable fluidised form:

If 1. Reynolds number is less than 2000, be Laminar Flow, the wind speed formula according to fully mechanized coal face inlet section viscous sublayer district: conventional C-language Programming Design is adopted to write fully mechanized coal face inlet section wind speed self-defining function;

If 2. Reynolds number is greater than 2000, be Turbulence Flow, the wind speed formula in comprehensive fully mechanized coal face inlet section viscous sublayer district: with non-circular workplace turbulent region wind speed profile formula: $v_x=\stackrel{\‾}{v}[1+3.17\sqrt{\mathrm{\α}}+2.28\sqrt{\mathrm{\α}}\ln (1-\frac{r}{r_0})]$

Wherein, v _xfor fully mechanized coal face turbulent region wind speed, v _x> 0, unit m/s; for fully mechanized coal face inlet section mean wind speed, unit m/s; R is the distance of arbitrfary point, fully mechanized coal face turbulent region (A) to fully mechanized coal face central point, unit m; r ₀for fully mechanized coal face central point is to the vertical range on workplace border and through arbitrfary point, fully mechanized coal face turbulent region (A), r ₀> r, unit m;

Conventional C-language Programming Design is adopted to write fully mechanized coal face inlet section wind speed self-defining function;

(3) fully mechanized coal face inlet section wind speed self-defining function is made an explanation in conventional fluid analysis software FLUENT, and be arranged to the boundary condition of fully mechanized coal face inlet section wind speed; Then intercoupled by the grain size analysis software EDEM of routine and fluid analysis software FLUENT, and derive dust granules coordinate data to obtain the fitting function of different-grain diameter dust movement track, simulation draws the movement locus of fully mechanized coal face different-grain diameter dust.