CN103617331B - A kind of vane type throws device discharge nozzle Shape Optimization for Structure method - Google Patents

Abstract

The invention discloses a kind of vane type and throw device discharge nozzle Shape Optimization for Structure method, it is characterized in that: step is as follows: 1), by the characteristics of motion of material in high-speed camera experimental observation discharge nozzle, combining with theoretical analysis sets up the mathematical model of material movement in discharge nozzle；2), use Eulerian-Lagrangian method that the Gas-solid Two-phase Flow in discharge nozzle is carried out numerical simulation, wherein material movement law uses User-Defined Functions, for above-mentioned built material movement mathematical model, and Numerical Simulation Results is compared with high-speed camera result of the test its reliability of checking；3), in the case of identical operating mode, choose discharging tubular construction shape and parameter, its inside Gas-solid Two-phase Flow is emulated, utilize material to leave the simulation result of movement velocity of discharge nozzle, determine the optimum results of discharging tubular construction shape.Present invention reduces the construction cycle, and improve the success rate of design efficiency, designing quality and primary development.

Description

A kind of vane type throws device discharge nozzle Shape Optimization for Structure method

Technical field

The invention belongs to the crossing domain of agricultural fibrous materials results and processing equipment design and computer-aided design, tool Say body, relate to a kind of vane type and throw device discharge nozzle Shape Optimization for Structure method.

Background technology

Vane type throws device and is widely used in various herbage, silage harvester, straw chopping and returning machine, various rubs In the agricultural fibrous materials results such as broken machine and chipper and processing equipment.Vane type throws device mainly by throwing impeller, throwing Shell and discharge nozzle (including discharging straight tube and discharging elbow) etc. form.During work, high speed rotating throws produced by impeller Air stream assists conveying material at discharge nozzle.

In actual applications, vane type throws device and is primarily present and throws that power consumption is big, it is low to throw efficiency, easily blocking with And throw distance and can not meet the problems such as requirement.In order to by material throwing to specify position, discharge nozzle is by discharging straight tube and discharging Bend pipe two parts form.Material moves across bent portion branch along straight tube and collides with bend pipe outer wall, then along bend pipe outer wall Motion is until being spilled over.If the planform of discharge nozzle is designed to unreasonable, material is with the collision of tube wall, friction energy loss will Increasing, material leaves the speed of discharge nozzle to be reduced, and not only can make to throw power consumption and increase, throw efficiency and reduce, and throwing distance can not Meet requirement, and easily make to throw device blocking.

At present the external main method using experimental study by improved structure reduce vane type throw device power consumption, Raising throws efficiency and increase throws distance.Domestic mainly determine that some is specific by the method for theory analysis and experimental study Under the conditions of throw the structural parameters of device.Whether power consumption is little, it is high to throw efficiency, be difficult to obstruction and satisfied for the device that throws designed Throw required distance, also need to process model machine research experiment and just can determine that, as being unsatisfactory for requiring also to need to readjust its knot Structure and form parameter.Existence design R&D process cycle length, workload are big, high in cost of production defect, constrain carrying of product quality High.

Fluid Mechanics Computation emulation technology comparative maturity, throws the Optimal Structure Designing of device discharge nozzle for vane type Provide strong instrument.Utilize this technology can be with the motion feature of material in Fast simulation various real working condition bottom discharge pipe And speed, thus the optimizing design scheme of device discharge nozzle it is achieved with throwing without manufacturing physical prototyping, not only shorten Construction cycle, and improve the success rate of design efficiency, designing quality and primary development.

Summary of the invention

The technical problem to be solved in the present invention is to overcome drawbacks described above, it is provided that a kind of adaptation based on Computer Simulation is quick The vane type of exploitation demand throws device discharge nozzle Shape Optimization for Structure method, motion when utilizing material to leave discharge nozzle Simulation result, determines discharging tubular construction Shape optimization designs scheme.One the most rational blade of planform of final acquisition Formula throws device discharge nozzle, thus is effectively reduced and throws device power consumption, improves and throws efficiency, meets and throws required distance.

For solving the problems referred to above, the technical solution adopted in the present invention is:

A kind of vane type throws device discharge nozzle Shape Optimization for Structure method, it is characterised in that: step is as follows:

1), by the characteristics of motion of material in high-speed camera experimental observation discharge nozzle, combining with theoretical analysis sets up discharge nozzle The mathematical model of middle material movement；

2), use the Eulerian-Lagrangian approach in cfdrc Fluent to the gas-particle two-phase in discharge nozzle Flowing carries out numerical simulation, and wherein material movement law uses User-Defined Functions, for above-mentioned built material movement mathematical modulo Type, and Numerical Simulation Results is compared with high-speed camera result of the test its reliability of checking；

3), in the case of identical operating mode, choose discharging tubular construction shape and parameter, its inside Gas-solid Two-phase Flow is carried out Emulation, utilizes material to leave the simulation result of movement velocity of discharge nozzle, determines the optimum results of discharging tubular construction shape.

As the technical scheme of a kind of improvement, described step 1) in set up and throw the mathematics of material movement in device discharge nozzle Model:

Be can be observed after material particles leaves and throw blade, to hang down along discharging straight tube in decentralized manner by high-speed camera test Directly moving upward, until colliding with discharging elbow upper wall, moving until being pulled out away from out along bend pipe upper wall the most in dense manner Material pipe；

(1), when material particles has just left and thrown blade, the centrifugal force being subject to is much larger than the centrifugal force suffered by air-flow, therefore Material speed υ_pMore than air-flow average speed υ_a, the air-flow active force P to material_aFor aerodynamic drag, direction and material movement direction On the contrary；Material is transported along discharging straight tube under gravity, frictional impact resistance and aerodynamic drag effect in decentralized manner vertically upward Dynamic, its speed is gradually reduced, and when dropping below air velocity, air-flow produces aerodynamic force upwards to material, maintains material Speed upwards；

In discharging straight tube, the equation of material movement is:

$m_p\frac{d^{2}l}{{\mathrm{dt}}^2}=P_a-m_{p}g---\left(1\right)$

In equation, m_pFor material particles quality, unit is kg；L is granule stream motion path, and unit is m；T is granule motion Time, unit is s；G is acceleration of gravity, and unit is m/s²；P_aFor aerodynamic force, unit is N； Wherein υ_sFor material particles floating velocity, unit is m/s.

(2) material collides with its outer tube wall after entering discharging elbow, if collision is inelastic collision, and the average speed of collision rift Degree is υ₂, then

$\frac{1}{2}{m}_p{\mathrm{\υ}}_2^2=\frac{1}{2}{m}_p{\mathrm{\υ}}_1^2-1/2m_p{\mathrm{\υ}}_1^2{\sin }^2\mathrm{\α}+m_p{\mathrm{\υ}}_1{\mathrm{sin\αf\υ}}_m---\left(2\right)$

In formula, υ₁Average speed before colliding with tube wall for material, unit is m/s；α is impingement angle；F is material and tube wall Coefficient of friction；υ_mFor the average speed in collision process,Unit For m/s；

(3) material with tube wall collision rift under the influence of centrifugal force, separates with air-flow, at gravity m_pG, centrifugal forceAnd frictional forceUnder effect, moving along bend pipe upper wall in dense manner, material is transported Dynamic equation is:

$m_p\frac{d^{2}l}{{\mathrm{dt}}^2}+m_{p}gcos\frac{l}{r}+f\[\frac{m_p}{r}{\left(\frac{dl}{dt}\right)}^2-m_{p}gsin\frac{l}{r}\]=0---\left(3\right)$

In formula, r is discharging elbow outer wall radius of curvature, and unit is m.

As the technical scheme of a kind of improvement, described step 2) in set up gas in discharge nozzle based on Eulerian-Lagrangian approach Fixed double phase flow moves numerical simulation model:

Choose whole vane type and throw the flowing space of device as zoning, at the pre-processing software GAMBIT of CFD The physical model of middle generation zoning, and zoning is carried out stress and strain model；The import of zoning is set to speed import Boundary condition, outlet is set to pressure export, and given standard atmosphere condition is as pressure side dividing value；

Use the Gas-solid Two-phase Flow in Eulerian-Lagrangian approach simulation discharge nozzle, under eulerian coordinate system, i.e. investigate gas The motion of stream, studies the motion of solid particle under Lagrange remainder；Choose the DPM (Discrete in Fluent software Phase Model) model, it is considered to material stream and the interaction of air-flow, use coupling to calculate；Wherein material movement in discharge nozzle Rule uses User Defined UDF (User-Defined Functions) function, for above-mentioned built material movement mathematical model； Numerical simulation result is compared with the high-speed camera result of the test of material movement in discharge nozzle, checking mathematical model and numerical computations The reliability of result.

As the technical scheme of a kind of improvement, described step 3) utilize numerical simulation model that vane type throws device discharging Tubular construction shape is optimized

Under identical operating mode, choose discharging tubular construction shape and parameter respectively, gas-solid two internal to variously-shaped discharge nozzle Flowing emulates mutually, utilizes material to leave the simulation result of discharge nozzle speed, determines the optimum results of discharging tubular construction shape； Under the same terms, the speed that material leaves discharge nozzle is the highest, then material and tube wall collide, friction energy loss is the least, and power consumption is the least, Throw efficiency the highest, throw distance the most remote, be more not easily blocked.

Owing to have employed technique scheme, compared with prior art, the present invention can be with the various real working condition of Fast simulation The motion feature of material and speed in bottom discharge pipe, thus be achieved with throwing device discharge nozzle without manufacturing physical prototyping Optimizing design scheme, not only shortens the construction cycle, and improves the success of design efficiency, designing quality and primary development Rate.

The invention will be further described with detailed description of the invention below in conjunction with the accompanying drawings simultaneously.

Accompanying drawing explanation

Fig. 1 is the structural representation that an embodiment of the present invention middle period chip throws device；

Fig. 2 is material motion in discharging elbow and stress schematic diagram in an embodiment of the present invention；

Fig. 3 is emulation and the measured result contrast schematic diagram of material movement velocity in discharging elbow；

Fig. 4 is five kinds of curve shape schematic diagrams of discharging elbow outer wall；

Fig. 5 is material movement velocity simulation results contrast schematic diagram in different curve shape discharging elbow；

Fig. 6 is material movement velocity simulation results contrast schematic diagram in different cross section shape discharge nozzle.

Detailed description of the invention

Embodiment:

As shown in Figure 1, vane type throws device and includes throwing impeller 1, throwing shell 2 and discharge nozzle, discharge nozzle bag Include material straight tube 3 and discharging elbow 4.Vane type throws the known conditions of device: it is Φ that vane type throws device impeller outer diameter 700mm, width of blade 160mm, blade thickness 5mm, the number of blade 4, blade tilt is radial blade, and wheel speed is 650r/min. Thrown material is Semen Maydis straw chopping section, shreds length 20～25mm, average diameter 15.4mm, average density 9.21 × 10^-8kg/mm³.Feed quantity is 0.5kg/s.

(1), above each known parameters value is substituted into formula (1), (2) and (3).

(2), choose whole vane type and throw the flowing space of device as zoning.Pre-processing software at CFD GAMBIT generates the physical model of zoning, and zoning is carried out stress and strain model.The import of zoning is set to speed Degree inlet boundary condition, wherein material and air velocity are 6.5m/s.Outlet is set to pressure export, given standard atmosphere condition As pressure side dividing value.

Use the Gas-solid Two-phase Flow in Eulerian-Lagrangian approach simulation discharge nozzle, under eulerian coordinate system, i.e. investigate gas The motion of stream, studies the motion of solid particle under Lagrange remainder.Choose the DPM (Discrete in Fluent software Phase Model) model, it is considered to material stream and the interaction of air-flow, use coupling to calculate.Wherein material movement in discharge nozzle Rule uses User Defined UDF (User-Defined Functions) function, for above-mentioned built material movement mathematical model (1), (2) and (3).

High-speed camera by numerical simulation result Yu discharge nozzle (bend pipe outer wall radius of curvature is 2500mm) interior material movement Result of the test compares, as shown in Figure 3.The absolute error of analogue simulation value and test value between ± 8mm, relative error ± Between 5%, illustrate that the analogue value is the most identical with test value.Demonstrate the reliability of mathematical model and numerical result.

(3) the same terms (throw device impeller outer diameter be Φ 700mm, width of blade 160mm, blade thickness 5mm, blade Several 4, blade tilt is radial blade, throws Semen Maydis straw chopping section, wheel speed 650r/min, feed quantity 0.5kg/s) Under, choose respectively multiple discharge nozzle planform and parameter, such as discharging straight tube respectively with the bend pipe (bend pipe of a kind of radius of curvature Outer wall radius of curvature is 2500mm), the bend pipe of two kinds of radius of curvature (bend pipe outer wall radius of curvature be respectively 1500mm and 5500mm), Archimedes spiral bend pipe, logatithmic spiral bend pipe, trunnion axis parabola bend pipe etc. combine (accompanying drawing 4).Wherein A Ji The parabolical polar equation of Mead helical, logatithmic spiral and trunnion axis is respectively (4), (5) and (6).

R=3.784 θ (4)

R=203e^0.4θ (5)

$r={42}^2\frac{cos\mathrm{\θ}}{{\sin }^2\mathrm{\θ}}---\left(6\right)$

In formula, r is discharging elbow outer wall radius of curvature, and unit is m.θ is corner, as shown in Figure 4.To above-mentioned five yeast inoculation The internal Gas-solid Two-phase Flow of wire shaped discharge nozzle emulates, and the simulation result of material movement is as shown in Figure 5.Can by accompanying drawing 5 Know, in above-mentioned five kinds of curve shape discharge nozzles two kinds of radius of curvature bend pipe (bend pipe outer wall radius of curvature be respectively 1500mm and Average speed when 5500mm) material leaves discharge nozzle is the highest, for 7.89m/s.The average speed that material leaves discharge nozzle is the highest, So material and tube wall collision, friction energy loss the least, power consumption is the least, throws efficiency the highest, throw distance the most remote, be more difficult to block up Plug.The bend pipe of visible two kinds of radius of curvature relatively other four kinds of more reasonable structure.

In like manner can get sectional area, identical (area of section is 34596mm²Different discharge nozzle cross sectional shapes under the conditions of), i.e. Circular (R=104.97mm), square (186mmx186mm) and the optimizing design scheme of rectangle (279mmx124mm), such as accompanying drawing 6 Shown in.Accompanying drawing 6 is material movement simulation result comparison diagram in different cross section shape discharge nozzle, and as can be seen from Figure, circular cross-section goes out In material pipe, average material speed is slightly higher, this be due in circular cross-section discharge nozzle without wedge angle, the friction with material and collision effect Reason less than other two kinds of cross sections.Circular cross-section discharge nozzle is more square and square-section is more reasonable as can be seen here.

The present invention is not limited to above-mentioned preferred implementation, and anyone should learn and make under the enlightenment of the present invention Structure changes, every have with the present invention same or like as technical scheme, belong to protection scope of the present invention.

Claims (2)

1. a vane type throws device discharge nozzle Shape Optimization for Structure method, it is characterised in that: step is as follows:

1), by the characteristics of motion of material in high-speed camera experimental observation discharge nozzle, combining with theoretical analysis sets up thing in discharge nozzle The mathematical model of material motion；

2), use the Eulerian-Lagrangian approach in cfdrc Fluent to the Gas-solid Two-phase Flow in discharge nozzle Carrying out numerical simulation, wherein material movement law uses User-Defined Functions, for above-mentioned built material movement mathematical model, and Numerical Simulation Results is compared with high-speed camera result of the test its reliability of checking；

3), in the case of identical operating mode, choose discharging tubular construction shape and parameter, its inside Gas-solid Two-phase Flow is imitated Very, utilize material to leave the simulation result of movement velocity of discharge nozzle, determine the optimum results of discharging tubular construction shape；

Described step 1) in set up and throw the mathematical model of material movement in device discharge nozzle:

Be can be observed after material particles leaves and throw blade by high-speed camera test, in decentralized manner along discharging straight tube vertically to Upper motion, until colliding with discharging elbow upper wall, moves until being pulled out away from discharge nozzle along bend pipe upper wall the most in dense manner；

(1), when material particles has just left and thrown blade, the centrifugal force being subject to is much larger than the centrifugal force suffered by air-flow, therefore material Speed υ_pMore than air-flow average speed υ_a, the air-flow active force P to material_aFor aerodynamic drag, direction and material movement direction phase Instead；Material under gravity, frictional impact resistance and aerodynamic drag effect in decentralized manner along discharging straight tube upward vertical movement, Its speed is gradually reduced, and when dropping below air velocity, air-flow produces aerodynamic force upwards to material, maintains material upwards Speed；

In discharging straight tube, the equation of material movement is:

$m_p\frac{d^{2}l}{{\mathrm{dt}}^2}=P_a-m_{p}g---\left(1\right)$

In equation, mp is material particles quality, and unit is kg；L is granule stream motion path, and unit is m；T is granule movement time, Unit is s；G is acceleration of gravity, and unit is m/s2；Pa is aerodynamic force, and unit is N； Wherein υ s is material particles floating velocity, and unit is m/s；

(2) material collides with its outer tube wall after entering discharging elbow, if collision is inelastic collision, the average speed of collision rift is υ₂, then

$\frac{1}{2}{m}_p{\mathrm{\υ}}_2^2=\frac{1}{2}{m}_p{\mathrm{\υ}}_1^2-1/2m_p{\mathrm{\υ}}_1^2{\sin }^2\mathrm{\α}+m_p{\mathrm{\υ}}_1{\mathrm{sin\αf\υ}}_m---\left(2\right)$

In formula, υ₁Average speed before colliding with tube wall for material, unit is m/s；α is impingement angle；F is material and the rubbing of tube wall Wipe coefficient；υ_mFor the average speed in collision process,Unit is m/ s；

(3) material with tube wall collision rift under the influence of centrifugal force, separates with air-flow, at gravity m_pG, centrifugal forceAnd Frictional forceUnder effect, moving along bend pipe upper wall in dense manner, material movement equation is:

$m_p\frac{d^{2}l}{{\mathrm{dt}}^2}+m_{p}gcos\frac{l}{r}+f\[\frac{m_p}{r}{\left(\frac{dl}{dt}\right)}^2-m_{p}gsin\frac{l}{r}\]=0---\left(3\right)$

In formula, r is discharging elbow outer wall radius of curvature, and unit is m；

Described step 2) in set up Gas-solid Two-phase Flow numerical simulation model in discharge nozzle based on Eulerian-Lagrangian approach: choose Whole vane type throws the flowing space of device as zoning, generates and calculate district in the pre-processing software GAMBIT of CFD The physical model in territory, and zoning is carried out stress and strain model；The Ι mouth that enters of zoning is set to speed inlet boundary condition, goes out Mouth is set to pressure export, and given standard atmosphere condition is as pressure side dividing value；

Use the Gas-solid Two-phase Flow in Eulerian-Lagrangian approach simulation discharge nozzle, under eulerian coordinate system, i.e. investigate air-flow Motion, studies the motion of solid particle under Lagrange remainder；Choose the DPM (Discrete in Fluent software Phase Model) model, it is considered to material stream and the interaction of air-flow, use coupling to calculate；Wherein material movement in discharge nozzle Rule uses User Defined UDF (User-Defined Functions) function, for above-mentioned built material movement mathematical model； Numerical simulation result is compared with the high-speed camera result of the test of material movement in discharge nozzle, checking mathematical model and numerical computations The reliability of result.

2. throwing device discharge nozzle Shape Optimization for Structure method according to a kind of vane type described in claim 1, it is special Levy and be: described step 3) utilize numerical simulation model that vane type throws device discharge nozzle planform to be optimized

Under identical operating mode, choose discharging tubular construction shape and parameter respectively, Dual-Phrase Distribution of Gas olid internal to variously-shaped discharge nozzle Move and emulate, utilize material to leave the simulation result of discharge nozzle speed, determine the optimum results of discharging tubular construction shape；Identical Under the conditions of, the speed that material leaves discharge nozzle is the highest, then material and tube wall collide, friction energy loss is the least, and power consumption is the least, throws Efficiency is the highest, throws distance the most remote, is more not easily blocked.