34中英文雙語外文文獻(xiàn)翻譯成品流化床噴霧造粒機(jī)的計(jì)算流體力學(xué)-離散單元法（dem-cfd）建模

1、<p>　　外文標(biāo)題：DEM-CFD MODELLING OF A FLUIDIZED BED SPRAY GRANULATOR</p><p>　　外文作者：L Fries ， SH Sergiy Antonyuk ， S Palzer</p><p>　　文獻(xiàn)出處:International Conference on Fluidization-new Paradigm in

2、 Fluidization Engineering , 2011 , 66 (11) :2340–2355</p><p>　　英文2657單詞，13788 字符，中文3698 漢字。</p><p>　　此文檔是外文翻譯成品，無需調(diào)整復(fù)雜的格式哦！下載之后直接可用，方便快捷！只需二十多元。</p><p>　　DEM-CFD MODELLING OF A FLUI

3、DIZED BED SPRAY GRANULATOR</p><p>　　Lennart Fries, Sergiy Antonyuk, Stefan Heinrich1 and Stefan Palzer²</p><p>　　1 Institute of Solids Process Engineering and Particle Technology, Hamburg U

4、niversity of Technology</p><p>　　Denickestrasse 15</p><p>　　21073 Hamburg, Germany</p><p>　　T:+49-40-42878 2143; F:+49-40-42878-2678; E: lennart.fries@tuhh.de</p><p>　　

5、² Nestlé Research Center Vers-Chez-Les-Blanc, Department of Food Science and Technology Route du Jorat 57</p><p>　　1000 Lausanne 26, Switzerland</p><p><b>　　ABSTRACT</b><

6、;/p><p>　　Coupled DEM-CFD simulations have been performed to study the hydrodynamics of a Wurster granulator on the scale of individual particles. Based on extensive material tests, the collision behaviour of d

7、ry ?-Al2O3 particles is identified and incorporated into the model. The effect of process parameters like air flow rate and geometry details like the Wurster position is studied. Based on a physical description of the m

8、aterial properties, an effective tool for design and scale-up of a Wurster granu</p><p>　　INTRODUCTION</p><p>　　Fluidized bed spray granulation plays an important role in the manufacturing of po

9、wder granules in the food and pharmaceutical industries as it allows producing dust-free and free-flowing particles. Liquid binder is sprayed into a bed of solids to achieve granule growth. Looking on the micro-scale, af

10、ter the impact of droplets on granules or primary particles and wetting of the particles’ surface, drying of the binder layer and evaporation of the solvent initiates layer-wise binder deposition (c</p><p>　

11、　Fig. 1: Scheme of a Wurster granulator</p><p>　　The Wurster process is controlled by many parameters which can influence the quality of the coating layer. Although operating conditions and the equipment geo

12、metry have been developed through experiments and experience of the process, the actual influence of the fundamental mechanisms in the process is not well understood. The drying rate, and hence the film formation, is hig

13、hly dependent on the flow field of the gas and particle phases in the equipment</p><p>　　MATHEMATICAL MODEL</p><p>　　Following the concept of the kinetic theory of granular flow (KTGF), multipha

14、se CFD models have been established to describe the fluid dynamics of spout fluidized bed systems [1], [2]. The method allows simulating a lab-scale fluidized bed on a PC workstation within a reasonable period of time. Y

15、et, the method fundamentally lacks a description of the particle-particle interactions. Energy dissipation through non- ideal elastic collisions can only be incorporated to the model with the help of the</p><p

16、>　　To be able to model a fluidized bed system on the scale of individual particles, several authors have set up discrete particle models (DPM) [3], [4]. Some attempts have been made to model the fluidized bed spray gr

17、anulation process with DPM [5], [6], [7]. The concept of this modelling technique is briefly introduced in this section.</p><p>　　The discrete particle phase</p><p>　　The motion of each individu

18、al particle or droplet i with mass mi and volume Vi in the system is calculated using Newton's second law</p><p><b>　　dv ?</b></p><p><b>　　d 2r ? ?</b></p><

19、;p><b>　　? ? V ? ?</b></p><p><b>　　?????</b></p><p><b>　　m i i dt</b></p><p>　　m i i dt 2</p><p><b>　　Vi p</b><

20、;/p><p><b>　　iuv</b></p><p><b>　　1 ? ?gi</b></p><p><b>　　mig</b></p><p>　　Fcontact ,i</p><p><b>　　Fpp,i</b>

21、;</p><p><b>　　(1)</b></p><p>　　where vi is the velocity and ri the position of the element i. The forces on the right hand side of Eq. (1) are respectively due to the pressure gradie

22、nt, drag, gravity, contact forces (i.e. due to collisions) and other particle-particle interactions (for instance Van-der-Waals forces).</p><p>　　The interphase momentum transfer coefficient ? is modelled by

23、 combining the Ergun (1952) equation for dense regimes (? < 0.8) and the correlation proposed by Wen&Yu (1966) for the more dilute regimes (? > 0.8).</p><p>　　The continuous gas phase</p>&l

24、t;p>　　The gas phase is considered as continuum (Euler-Lagrange approach). The geometry of the apparatus is discretized in mesh cells and the motion of the gas phase is calculated using volume-averaged Navier-Stokes eq

25、uations.</p><p><b>　　? ???</b></p><p><b>　　?tg</b></p><p><b>　　?? ???? u</b></p><p><b>　　? ? 0</b></p><p>

26、<b>　　(2)</b></p><p><b>　　? ??? u</b></p><p>　　?tg g</p><p>　　?? ???? u u</p><p><b>　　? ? ?? ?p</b></p><p><b>

27、;　　? ??? τ</b></p><p><b>　　?? S</b></p><p><b>　　?? g g</b></p><p><b>　　(3)</b></p><p>　　Due to their presence and the volume f

28、raction they require, the particles influence the velocity profile of the gas phase. This effect is accounted for by adding a sink term Sp to the momentum balance, which contains the interphase momentum transfer coeffici

29、ent ? and closes the two-way-coupling. Forces between the gas and particle phase are of opposite direction and equal magnitude.</p><p>　　Contact model</p><p>　　In case of a collision between two

30、 particles, the contact forces are calculated according to a contact model based on the theory developed by Hertz (1882) [8] for the normal impact and a no-slip approximation of the model by Mindlin and Deresiewicz (1953

31、) [9] for the tangental part of the contact force, as proposed by Tsuji [10].</p><p><b>　　Fab,n</b></p><p><b>　　? ?kn</b></p><p>　　? ? 32 ? n</p><

32、p><b>　　??n</b></p><p><b>　　v ab,n</b></p><p><b>　　(4)</b></p><p>　　The elastic part of the contact force is represented by a non-linear spring

33、, where the</p><p>　　force is proportional to the spring stiffness kn</p><p>　　and the displacement ? 32 .</p><p>　　Additionally, to account for visco-elastic material properties th

34、at cause energy dissipation, a damping factor ?n related to the coefficient of restitution (Tsuji [10]) is included into the model.</p><p>　　The coefficient of restitution e is defined as the ratio of reboun

35、d velocity vr to impact velocity v.</p><p><b>　　en ?? v</b></p><p><b>　　(5)</b></p><p>　　It can be obtained through experiments, as described in the next se

36、ction.</p><p>　　MATERIALS AND METHODS</p><p>　　Free-fall tests</p><p>　　The impact and rebound behaviour of ?-Al2O3 granules was analyzed with the help of a free fall test setup as

37、shown in Fig. 2.</p><p>　　1 1 – stand</p><p>　　2 2 – vacuum nozzle 3 – thickness sensor</p><p><b>　　– light</b></p><p>　　– high-speed camera 6 - plate<

38、/p><p><b>　　3</b></p><p><b>　　4</b></p><p><b>　　6</b></p><p><b>　　5</b></p><p><b>　　1</b></p>

39、;<p><b>　　0.8</b></p><p><b>　　0.6</b></p><p><b>　　0.4</b></p><p><b>　　0.2</b></p><p><b>　　0</b></p

40、><p>　　012345</p><p><b>　　v in m/s</b></p><p>　　Fig. 2: Setup of free-fall tester</p><p>　　Fig. 3: Normal coefficient of restitution for visco-elastic Al2

41、O3 granules</p><p>　　The normal coefficient of restitution en is independent of the impact velocity v in the investigated range between 0.5 m/s and 5 m/s (Fig. 3, [11]). The experimental values are used to c

42、alibrate the contact model in the discrete particle model.</p><p>　　Coupled DEM-CFD Simulations</p><p>　　For numerical DPM simulations, a Glatt GF3 insert was modelled. The original geometry was

43、 supplied by Glatt Ingenieurtechnik GmbH (Weimar, Germany) and slightly simplified for the simulations, as shown in Fig. 4a. A representation of the mesh used for the fluid dynamics simulations is given in Fig. 4c. The c

44、ommercial software packages EDEM and Fluent were used to perform simulations with 150,000 spherical particles of a particle diameter dp = 2 mm, which corresponds to a batch size of 0.94 kg at</p><p>　　Additi

45、onally, air is injected by a nozzle which is situated at the center inside the Wurster tube. This study focuses on the fluid-dynamic behaviour and does not include the injection of liquid binder.</p><p><

46、b>　　180 mm</b></p><p>　　Fig. 4a: Simplified Wurster geometry (centered vertical cross section)</p><p>　　Fig. 4b: Visual representation scheme</p><p>　　Fig. 4c: Fluid mesh c

47、ells</p><p>　　In a series of case studies, the velocity of the inlet air, the jet injection velocity uspout, the distribution of air between Wurster and annulus and the gap distance hgap below the Wurster tu

48、be was varied. Material parameters were kept constant throughout the simulations as well as the height hW and diameter dW of the Wurster tube. The operating conditions in the case studies are summarized in Table 1.</p

49、><p>　　Table 1: Overview on the simulation scenarios in this work</p><p>　　SIMULATION RESULTS</p><p>　　Influence of gas velocity</p><p>　　The simulation results show that

50、the velocity of the air injected via the nozzle has a strong influence on the fluid-dynamics of the whole granulator. In Fig. 5, snapshots of the particle positions and their velocities are displayed. The colour indicate

51、s the particle velocity magnitude: blue particles move slowly (v < 0.5 m/s) and red particles are fast (v > 1.5 m/s). Three simulation cases are depicted at the same time step (t = 1.4 s).</p><p>　　Vis

52、ual representations of the simulation results in Fig. 5 and Fig. 8 are taken according to the scheme in Fig. 4b. The central vertical cross section of the apparatus and all parts behind that plane are shown. It can be se

53、en from Fig. 5 that a higher spout velocity causes higher particle velocities inside the Wurster tube. In the acceleration zone near the nozzle, the particles are concentrated to the center of the Wurster for high spout

54、velocities (case 3) whereas they are more evenly distribu</p><p>　　particle fountain increases with higher spout velocity from 430 mm above the nozzle tip in case 1 to 490 mm in case 3.</p><p>　

55、　case 1case 2case 3</p><p>　　Fig. 5: Instantaneous particle positions and velocity distributions inside the Wurster tube at time t = 1.4 s. Colours indicate the velocity magnitude.</p><p>　　To

56、 assess the radial distribution of particles in the granulator, horizontal slices were cut out of the simulated geometry. This was done at two different heights, as shown in Figure 4a. The thickness of each of the slices

57、 is 10 mm. The first slice is situated in the lower part of the granulator, just below the tip of the injection nozzle. The second slice contains the upper border of the Wurster tube and allows visualizing the flow condi

58、tions of particles entering the expansion. Fig. 6 and 7 sh</p><p>　　Slice 1Case 1Case 2Case 3</p><p>　　Fig. 6: Instantaneous horizontal distribution of particles in slice 1 at time t = 1.4 s.

59、</p><p>　　Comparing case 2 and 3 in slice 1 it can be seen that the gas velocity in the outer ring has a strong influence on the bed expansion. For case 3, a dense bed is seen in slice 1 where there is a hig

60、h porosity in case 2. Looking at the particles inside the Wurster tube it can be observed that the high spout velocity in case 3 tears the particles towards the center of the tube. A comparison between case 1 and 2 in Fi

61、g. 6 reveals that at identical flow conditions in the annulus, the gas injection af</p><p>　　Slice 2Case 1Case 2Case 3</p><p>　　Fig. 7: Instantaneous horizontal distribution of particles in s

62、lice 2 at time t = 1.0 s</p><p>　　In slice 2 at the upper end of the Wurster tube, only few particles are present (Fig. 7). Their movement is directed upwards inside the tube and downwards in the annulus at

63、all three cases, indicating that the circulating regime is intact in a wide fluidization range. Along the border of the Wurster tube, a deceleration of the particles can be observed in case 1, whereas at high spout veloc

64、ity, all particles mover faster than 1 m/s at this level (case 3). For low spout velocities as in case 1, s</p><p>　　Influence of the gap distance below the Wurster tube</p><p>　　The gap distanc

65、e between the distributor plate and the Wurster tube is a parameter that strongly influences the particle dynamics inside the granulator as it controls the recirculation of particles into the spout. Gaps of 10 mm and 20

66、mm were compared.</p><p>　　case 3case 4</p><p>　　Fig. 8: Instantaneous particle position and velocity distributions in the Wurster zone for different gap distances at time t = 1.4 s</p>

67、<p>　　It can be seen in Fig. 8 that a larger gap distance below the Wurster increases the number of particles that are transported into the tube. In case 3, in the lower half of the Wurster particles are only presen

68、t in the center of the tube. All particles rise at a velocity magnitude above 1 m/s which is indicated by green and red colour. Contrary to that, in case 4 particles can be found spread over the whole diameter of the Wur

69、ster tube. Near the wall of the tube they move at low velocity, indicat</p><p>　　CONCLUSIONS</p><p>　　Process parameters like the spout velocity and geometrical settings like the Wurster gap hei

70、ght influence the fluid-dynamics of a Wurster granulator, which was analysed with the help of coupled DEM-CFD-simulations. Based on experimental data of the impact behaviour of visco-elastic particles, the fluidization r

71、egime and based on that the functionality of a Wurster granulator can be predicted. Future measurements in a real Wurster coater will deliver results to validate the model.</p><p>　　ACKNOWLEDGEMENTS</p>

72、;<p>　　We would like to thank Nestec S.A. for the financial support and Dipl.-Ing. Michael Jacob from Glatt Ingenieurtechnik GmbH Weimar for the supply of geometry data.</p><p>　　REFERENCES</p>

73、<p>　　[1] Gryczka O., Heinrich S., Deen N.G., et al.: Characterization and CFD-modeling of the hydrodynamics of a prismatic spouted bed apparatus. CES 64 (14), 2009, 3352- 3375.</p><p>　　[

74、2]Karlsson, S., Rasmuson, A., van Wachem, B, Niklasson Björn, I.: CFD Modeling of the Wurster Bed Coater. AIChE Journal 55 (10), 2009, pp. 2578-2590.</p><p>　　[3]Hoomans, B.P.B., Kuipers, J.A.M.,

75、Briels, W.J., Van Swaaij, W.P.M.: Discrete particle simulation of bubble and slug formation in a two-dimensional gas-fluidised</p><p>　　bed: a hard-sphere approach. CES 51 (1), 1996, 99–118.</p><

76、p>　　[4]Tsuji, Y., Kawaguchi, T., Tanaka, T.: Discrete particle simulation of two- dimensional fluidized bed. Powder Technology 77 (1), 1993, 79–87.</p><p>　　[5]Goldschmidt, M.J.V., Kuipers, J.A.M.: Disc

77、rete element modelling of fluidisedbed spray granulation. Powder Technology 138, 2003, 39-45.</p><p>　　[6]Gantt, J.A., Gatzke, E.P.: High-shear granulation modeling using a discrete elementsimulation a

78、pproach. Powder Technology 156 (2005) pp. 195-212.</p><p>　　[7] Kafui, D.K., Thornton, C.: Fully-3D DEM simulation of fluidised bed spray granulation using an exploratory surface-energy based spray

79、zone concept. PowderTechnology 184, 2008, 177-188.</p><p>　　[8]Hertz, H. Über die Berührung fester elastischer Körper. Journal für die Reineund Angewandte Mathematik 92, 1882, 156-17

80、1.</p><p>　　[9]Mindlin, R.D., Deresiewicz, H.: Elastic spheres in contact under varying oblique forces. Transactions of ASME, Series E. Journal of applied Mechanics 20, 1953,</p><p><b>　

81、　327-344.</b></p><p>　　[10]Tsuji, Y., Tanaka, T., Ishida, T.: Lagrangian numerical simulation of plug flow of cohesionless particles in a horizontal pipe. Powder Technology 71, 1992, 239-250.</p>

82、;<p>　　[11] Antonyuk, S., Heinrich, S., Tomas, J., Deen, N.G., van Buijtenen, M.S. and J.A.M. Kuipers: Energy absorption during compression and impact of dry elastic-plastic spherical granules, in Proof in Granula

83、r Matter, December 2009.</p><p><b>　　KEY WORDS</b></p><p>　　Fluidized bed spray granulation, discrete element modelling, Wurster coater, CFD, fluid dynamics</p><p>　　流化床

84、噴霧造粒機(jī)的計(jì)算流體力學(xué)-離散單元法(DEM-CFD)建模</p><p>　　Lennart Fries, Sergiy Antonyuk, Stefan Heinrich1 and Stefan Palzer²</p><p><b>　　摘要</b></p><p>　　耦合DEM-CFD仿真已被用于去研究單個(gè)顆粒尺度Wurst

85、er造粒機(jī)的流體動(dòng)力學(xué)。 </p><p>　　在對(duì)廣泛材料測試的基礎(chǔ)上，干 ?-Al2O3顆粒的碰撞行為得到確定并將其納入了</p><p>　　模型之中。 并進(jìn)一步研究了氣流速率和具體幾何形狀，像Wurster位置等工藝</p><p>　　參數(shù)帶來的影響。 根據(jù)對(duì)材料性能的物理性描述，可以獲得用于設(shè)計(jì)和放大</p><p>　　Wurs

86、ter造粒機(jī)的有效工具。</p><p><b>　　引言</b></p><p>　　由于流化床噴霧造粒允許產(chǎn)生無塵和自由流動(dòng)的顆粒，它在食品和制藥工業(yè)中制造粉末</p><p>　　顆粒中起著重要的作用。將液體粘合劑噴到固體床中以實(shí)現(xiàn)顆粒的生長。從微觀上看，</p><p>　　在液滴滴到顆粒表面后，就會(huì)產(chǎn)生頭部顆粒

87、變得濕潤的影響，之后粘合劑層的干燥和溶</p><p>　　劑的蒸發(fā)引發(fā)分層粘合劑的沉積（涂覆）。 Wurster是制藥行業(yè)用于包衣片劑的常用技</p><p>　　術(shù)。如圖1所示，圓柱形導(dǎo)流管垂直插入造粒機(jī)中。與底部噴霧噴嘴相結(jié)合，Wurster幾</p><p>　　何形狀引起顆粒的循環(huán)運(yùn)動(dòng)并將幾何形狀分為兩個(gè)區(qū)域。在Wurster管內(nèi)部的中心部分，</p

88、><p>　　顆粒通過噴口向上輸送。顆粒在膨脹室中減速并下落到管外的顆粒密集區(qū)域，同時(shí)它們</p><p>　　被溫暖的流化空氣干燥。在密集區(qū)域，顆粒被運(yùn)回到Wurster管中，并且在床中的循環(huán)</p><p><b>　　運(yùn)動(dòng)得以重復(fù)進(jìn)行。</b></p><p>　　Fig. 1: Scheme of a Wurster

89、 granulator</p><p>　　Wurster工藝由許多影響涂層質(zhì)量的參數(shù)控制。 雖然操作條件和設(shè)備幾何形狀是通過過程實(shí)驗(yàn)和經(jīng)驗(yàn)而得來的，但在過程中所表現(xiàn)出的基本機(jī)制的實(shí)際影響尚不完全清楚。 干燥速率以及由此形成的薄膜高度依賴于設(shè)備中氣體和顆粒相的流速場。</p><p><b>　　數(shù)學(xué)模型</b></p><p>　　根據(jù)顆粒流

90、動(dòng)力學(xué)理論（KTGF）的概念，已經(jīng)建立了多相CFD模型來描述噴口流化床系統(tǒng)的流體動(dòng)力學(xué)[1]，[2]。 該方法允許在合理的時(shí)間段內(nèi)在PC工作站上模擬實(shí)驗(yàn)室規(guī)模的流化床。 然而，該方法從根本上缺乏對(duì)粒子 - 粒子相互作用的描述。 通過不達(dá)標(biāo)的彈性碰撞引起的能量耗散只能在恢復(fù)系數(shù)e的幫助下結(jié)合到模型中。</p><p>　　為了能夠在單個(gè)顆粒的尺度上對(duì)流化床系統(tǒng)進(jìn)行建模，一些作者建立了離散顆粒模型</p>

91、<p>　　（DPM）[3]，[4]。 有人嘗試用DPM模擬流化床噴霧造粒工藝[5，6，7]。 本節(jié)簡要介</p><p>　　紹了這種建模技術(shù)的概念。</p><p><b>　　離散顆粒相</b></p><p>　　使用牛頓第二定律計(jì)算系統(tǒng)中質(zhì)量為mi和體積為Vi的每個(gè)單獨(dú)粒子或液滴i的運(yùn)動(dòng)</p><p

92、><b>　　dv ?</b></p><p><b>　　d 2r ? ?</b></p><p><b>　　? ? V ? ?</b></p><p><b>　　?????</b></p><p><b>　　m i i d

93、t</b></p><p>　　m i i dt 2</p><p><b>　　Vi p</b></p><p><b>　　iuv</b></p><p><b>　　1 ? ?gi</b></p><p><b>　

94、　mig</b></p><p>　　Fcontact ,i</p><p><b>　　Fpp,i</b></p><p><b>　　(1)</b></p><p>　　其中 vi 是速度， ri 是元素i的位置。 等式（1）右邊的力分別由于壓力梯度、阻力、重力，接觸力（即由于碰撞）

95、和其他粒子 - 粒子相互作用（例如Van-der-Waals力）而產(chǎn)生。</p><p>　　通過結(jié)合Ergun（1952）密相體系方程（?<0.8）和Wen＆Yu（1966）提出的關(guān)于更稀</p><p>　　體系（? > 0.8）相關(guān)性模擬相間動(dòng)量傳遞系數(shù)?。</p><p><b>　　連續(xù)氣相</b></p>

96、<p>　　氣相被認(rèn)為是連續(xù)的（歐拉 - 拉格朗日方法）。 該裝置的幾何形狀在網(wǎng)格單元中被</p><p>　　離散化，并且氣體相的運(yùn)動(dòng)是使用體積平均的Navier-Stokes方程來計(jì)算的。</p><p><b>　　? ???</b></p><p><b>　　?tg</b></p>&l

97、t;p><b>　　?? ???? u</b></p><p><b>　　? ? 0</b></p><p><b>　　(2)</b></p><p><b>　　? ??? u</b></p><p>　　?tg g</p>

98、;<p>　　?? ???? u u</p><p><b>　　? ? ?? ?p</b></p><p><b>　　? ??? τ</b></p><p><b>　　?? S</b></p><p><b>　　?? g g</b>&

99、lt;/p><p><b>　　(3)</b></p><p>　　由于它們的存在和它們所需的容積率，顆粒影響了氣相的速度分布。 這個(gè)影響是通過</p><p>　　在動(dòng)量平衡中增加一個(gè)匯項(xiàng)Sp來說明的，其中包含了相間動(dòng)量傳遞系數(shù) ?并且關(guān)閉了</p><p>　　雙向耦合。 氣體和顆粒相之間的力量方向相反，幅度相等。<

100、;/p><p><b>　　碰撞模型</b></p><p>　　在兩個(gè)粒子碰撞的情況下，接觸力是根據(jù)Hertz發(fā)展出來的（1882）[8]的正常碰撞和</p><p>　　Mindlin以及Deresiewicz的模型無滑動(dòng)近似理論計(jì)算出來的，在接觸力 1953年）[9]</p><p>　　的切線部分，這是由Tsu [1

101、0]提出的。</p><p><b>　　Fab,n</b></p><p><b>　　? ?kn</b></p><p>　　? ? 32 ? n</p><p><b>　　??n</b></p><p><b>　　v ab,n<

102、/b></p><p><b>　　(4)</b></p><p>　　接觸力的彈性部分由非線性彈簧表示，其中，力與彈簧剛度kn和位移? 32 .成比例。</p><p>　　此外，為了考慮導(dǎo)致能量耗散的粘彈性材料屬性，模型中包含與恢復(fù)系數(shù)有關(guān)的阻尼因子（Tsuji [10]）。</p><p>　　恢復(fù)系數(shù)e被定

103、義為回彈速度vr與沖擊速度vr之比。</p><p><b>　　en ?? v</b></p><p><b>　　(5)</b></p><p>　　可以通過實(shí)驗(yàn)得到，并在下一部分進(jìn)行闡述。</p><p><b>　　材料以及方法</b></p><

104、p><b>　　自由落體測試</b></p><p>　　如圖2所示，在自由落體試驗(yàn)裝置的幫助下，分析了?-Al2O3顆粒的沖擊和回彈習(xí)性。</p><p>　　1 1 – stand</p><p>　　2 2 – vacuum nozzle 3 – thickness sensor</p><p><

105、b>　　– light</b></p><p>　　– high-speed camera 6 - plate</p><p><b>　　3</b></p><p><b>　　4</b></p><p><b>　　6</b></p><

106、;p><b>　　5</b></p><p><b>　　1</b></p><p><b>　　0.8</b></p><p><b>　　0.6</b></p><p><b>　　0.4</b></p>&l

107、t;p><b>　　0.2</b></p><p><b>　　0</b></p><p>　　012345</p><p><b>　　v in m/s</b></p><p>　　Fig. 2: Setup of free-fall tester</p

108、><p>　　Fig. 3: Normal coefficient of restitution for visco-elastic Al2O3 granules</p><p>　　在0.5m / s至5m / s的范圍內(nèi)，正常的恢復(fù)系數(shù)en 與沖擊速度v無關(guān)（圖3，[11]）。 實(shí)驗(yàn)值用于校準(zhǔn)離散顆粒模型中的接觸模型。</p><p>　　耦合DEM-CFD模擬&l

109、t;/p><p>　　對(duì)于數(shù)字DPM仿真，Glatt GF3管芯被模擬。原始幾何由Glatt Ingenieurtechnik GmbH</p><p>　?。╓eimar，Germany）提供，并且為了模擬而略微簡化，如圖4a所示。圖4c給出了用</p><p>　　于流體動(dòng)力學(xué)模擬的網(wǎng)格表示。使用商業(yè)軟件包EDEM和Fluent進(jìn)行了150,000個(gè)粒徑</p

110、><p>　　dp = 2mm的球形顆粒的仿真，其對(duì)應(yīng)的批量大小為0.94kg，平均顆粒密度為1500</p><p>　　kg/m³。根據(jù)實(shí)驗(yàn)結(jié)果，恢復(fù)系數(shù)設(shè)為0.8?？諝馔ㄟ^由三個(gè)區(qū)域組成的分段分配板</p><p>　　被引入到設(shè)備的底部。在Wurster管下方，由于板的較大孔隙率，流化空氣速度高于</p><p><b&

111、gt;　　環(huán)帶中的流速。</b></p><p>　　另外，空氣通過位于Wurster管內(nèi)部中心的噴嘴噴射。這項(xiàng)研究側(cè)重于流體動(dòng)力學(xué)習(xí)性</p><p>　　，不包括注入的液體粘合劑。</p><p><b>　　180 mm</b></p><p>　　Fig. 4a: Simplified Wurster

112、 geometry (centered vertical cross section)</p><p>　　Fig. 4b: Visual representation scheme</p><p>　　Fig. 4c: Fluid mesh cells</p><p>　　在一系列案例研究中，入口空氣速度、射流注入速度uspout，Wurster與環(huán)空之間的空氣分