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Research on mud dispersion legislation of absolutely mechanized mining faces beneath completely different inclinations and monitoring closed mud management technique

The mathematical mannequin on this examine consists of the Navier–Stokes equation (NS; the Eulerian technique) in polar coordinates23. For turbulent circulation, the usual okay–ε two-equation mannequin was used. The Lagrangian technique and discrete part mannequin have been used to unravel the dispersion legislation of working flour mud.

Wind circulation mannequin

The okay–ε equation mannequin primarily based on the Reynolds time-averaged NS has been broadly utilized in finding out the dispersion of complicated particles. Suppose u, v, and w are the rate elements within the x-, y-, and z-directions, respectively. Subsequently, the pace is expressed because the sum of the instantaneous pulsating pace and time-averaged pace24,25,26

$${textual content{u}} = overline{u} + u^{prime } , {textual content{v}} = {overline{textual content{v}}} + {textual content{v}}^{prime } ,{textual content{w}} = {overline{textual content{w}}} + {textual content{w}}^{prime }$$

(1)

Usually, the airflow state of the working floor is thought to be an incompressible fluid, and the continuity equation is27,28

$$frac{{partialuprho }}{{partial {textual content{t}}}} + frac{{partialuprho {textual content{u}}_{{textual content{i}}} }}{{partial {textual content{x}}_{{textual content{i}}} }} = 0$$

(2)

the place ρ is the fuel density (kg/m3), and t is the time. When the airflow is in a gentle state, the density doesn’t change with time and will be written as

$$frac{{partial left( {uprho {textual content{u}}} proper)}}{{partial {textual content{x}}}} + frac{{partial left( {uprho {textual content{v}}} proper)}}{{partial {textual content{y}}}} + frac{{partial left( {uprho {textual content{w}}} proper)}}{{partial {textual content{z}}}} = 0$$

(3)

The Reynolds time-averaged NS equation is used to derive and calculate the renormalized okay–ε equation utilizing the mathematical technique of renormalization.

The (okay) equation is29,30

$$frac{{partial left( {uprho {textual content{okay}}} proper)}}{{partial {textual content{t}}}} + frac{{partial left( {uprho {textual content{ku}}_{{textual content{i}}} } proper)}}{{partial {textual content{x}}_{{textual content{i}}} }} = frac{partial }{{partial {textual content{x}}_{{textual content{j}}} }}left[ {left( {upalpha _{{text{k}}}upmu _{{{text{eff}}}} } right)frac{{partial {text{k}}}}{{partial {text{x}}_{{text{j}}} }}} right] + {textual content{G}}_{{textual content{okay}}} + {textual content{G}}_{{textual content{b}}} – {uprho varepsilon }$$

(4)

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Within the system, okay is the turbulent kinetic power, m2/s2; (alpha_{okay}) is the reciprocal of the efficient Prandtl variety of the turbulent kinetic power, that’s, (alpha_{okay} = frac{1}{{sigma_{okay} }} = 1.0); (mu_{eff}) is the viscosity coefficient; (G_{okay}) is the turbulent kinetic power attributable to the common velocity gradient; and (G_{b}) is the turbulent kinetic power attributable to the affect of buoyancy.

The ε equation is31,32

$$frac{{partialuprho {textual content{okay}}}}{{partial {textual content{t}}}} + frac{{partial left( {{uprho varepsilon }{textual content{u}}_{{textual content{i}}} } proper)}}{{partial {textual content{x}}_{{textual content{i}}} }} = frac{partial }{{partial {textual content{x}}_{{textual content{j}}} }}left[ {left( {upalpha _{upvarepsilon } {upmu }_{{{text{eff}}}} frac{{partialupvarepsilon }}{{partial {text{x}}_{{text{j}}} }}} right)} right] + {textual content{C}}_{{1upvarepsilon }} frac{upvarepsilon }{{textual content{okay}}}left( {{textual content{G}}_{{textual content{okay}}} + {textual content{C}}_{{3upvarepsilon }} {textual content{G}}_{{textual content{b}}} } proper) – {textual content{C}}_{{2upvarepsilon }}uprho frac{{upvarepsilon ^{2} }}{{textual content{okay}}}$$

(5)

$$left{ {start{array}{*{20}c} {upmu _{{{textual content{eff}}}} =upmu _{{textual content{t}}} +upmu } {upmu _{{textual content{t}}} =uprho {textual content{C}}_{upmu } frac{{{textual content{okay}}^{2} }}{upvarepsilon }} finish{array} } proper.$$

(6)

Within the system, ε is the turbulent power dissipation fee, m2/s3; (C_{1varepsilon }), (C_{2varepsilon }), and (C_{3varepsilon }) are empirical constants; usually, the default is (C_{1varepsilon } = 1.43), (C_{2varepsilon } = 1.91), and (C_{3varepsilon } = 0.09); (mu_{t} {textual content{and}} mu) are the viscosity coefficients of turbulent and laminar circulation; and (alpha_{varepsilon }) is the reciprocal of the efficient Prandtl variety of the dissipation fee (alpha_{varepsilon } = frac{1}{{sigma_{varepsilon } }} = 0.768).

Mud discrete mannequin

The Euler–Lagrange technique was used to calculate the thought, the principle part is described by the Euler technique, the particle time period is described by the Lagrangian technique, and the fuel–strong two-phase circulation discrete part mannequin simulation of mud particles was used. In essence, the calculation of the trajectory of the working mud includes the mixing of the differential equation of the pressure appearing on the mud33,34,35. Subsequently, the differential equations of those forces within the Cartesian coordinate system will be expressed as follows (right here, the x-axis route is taken into account an instance)

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$$frac{{{textual content{du}}_{{textual content{p}}} }}{{{textual content{dt}}}} = {textual content{F}}_{{textual content{D}}} left( {{textual content{u}} – {textual content{u}}_{{textual content{p}}} } proper) + frac{{{textual content{g}}_{{textual content{x}}} left( {uprho _{{textual content{p}}} -uprho } proper)}}{{uprho _{{textual content{p}}} }} + sum {vec{textual content{F}}}_{{textual content{x}}}$$

(7)

Within the system, (u_{p }) is the particle velocity, m/s; t is the time, s; (u) is the relative velocity of the fluid, m/s; (g_{x }) is the gravitational acceleration within the x route, m/s2; (F_{D}) is the resistance of the particle, N; (mu) is the hydrodynamic viscosity, Pa*s; (rho) is the fluid density, kg/m3; (rho_{p}) is the particle density, kg/m3; and (sum {vec{textual content{F}}}_{x}) is different forces within the (x) route (e.g., “obvious mass pressure,” thermal, the resultant pressure of swimming pressure, and Brown pressure).

$${textual content{F}}_{{textual content{D}}} = frac{{18upmu }}{{uprho _{{textual content{p}}} {textual content{d}}_{{textual content{p}}}^{2} }}frac{{{textual content{C}}_{{textual content{D}}} {textual content{Re}}}}{24}$$

(8)

$${textual content{Re}} = frac{{uprho {textual content{d}}_{{textual content{p}}} left| {{textual content{u}}_{{textual content{p}}} – {textual content{u}}} proper|}}{upmu }$$

(9)

$${textual content{C}}_{{textual content{D}}} = {textual content{a}}_{1} + frac{{{textual content{a}}_{2} }}{{{textual content{Re}}}} + frac{{{textual content{a}}_{3} }}{{{textual content{Re}}^{2} }}$$

(10)

the place ({textual content{d}}_{{textual content{p}}}) is the particle diameter (m); ({textual content{Re }}) is the relative Reynolds variety of the particle; ({textual content{C}}_{{textual content{D}}}) is the drag coefficient; and ({textual content{a}}_{1}), ({textual content{a}}_{2}), and ({textual content{a}}_{3}) are constants inside a sure Reynolds quantity vary.

To extend the accuracy of descriptions of the motion of respirable mud particles, this examine launched a discrete ingredient collision mannequin to extend their suitability for area apply36. Utilizing Newton’s second legislation, the unusual differential equation that controls the movement of particles is expressed as follows:

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$${textual content{m}}_{{textual content{p}}} frac{{{textual content{d}}overrightarrow {{textual content{v}}} }}{{{textual content{dt}}}} = vec{F}_{Drag} + vec{F}_{Strain} + vec{F}_{gravitation} + vec{F}_{Digital – mass} + vec{F}_{Different}$$

(11)

$$overrightarrow {{textual content{v}}} = frac{{{textual content{dx}}}}{{{textual content{dt}}}}$$

(12)

For a given collision pair, the magnitude of the spring fixed of the traditional contact pressure ought to no less than fulfill the next circumstances: for the biggest inclusion and the best relative velocity within the collision pair, the spring fixed ought to be sufficiently excessive to make the recoil of the 2 packages collide with the bundle diameter, and the utmost overlap shouldn’t be too giant. The spring fixed will be written as

$${textual content{Ok}} = frac{{uppi v_{c}^{2} }}{{3varepsilon_{D}^{2} }}Drho$$

(13)

the place ({textual content{v}}_{{textual content{c}}}) is the relative velocity between two colliding particles, (varepsilon_{D}) is the diameter allowed to overlap, D is the bundle diameter, and (rho) is the particle mass density.

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