1、AStudyoftheGasFlowthroughAirJetHeuy-DongKim,Chae-MinLim,Ho-JoonLee,Doo-HwanAir jet loom，asone oftheshuttlelesslooms，transportsAStudyoftheGasFlowthroughAirJetHeuy-DongKim,Chae-MinLim,Ho-JoonLee,Doo-HwanAir jet loom，asone oftheshuttlelesslooms，transportsa o warps viscosity and kinetic energy of an air

2、 jet. Perfomance of this picking system depends on the ability of instantaneous inhalation/exhaust, configuration of nozzle, operation characteristics of a check valve, etc. In the recent past, many studies have reported on the air jet discharged from a nozzle exit, but studiesfor understanding flow

3、 field characteristics ted with shear layer and shock wave/boundary he nozzle were not conducted his r, a study wasperformed to heflow he air jet nozzle n tube and validated with previous experimental data from the compuion study showhe sudepends significantly on the length of available. The results

4、 ic flow regime, the flow tube. As nozzle re increase, drag force acting on the string also increase. For a longer acceleration the total re lossis large,owingto thefrictional Keywords: compressible flow, nozzle, shear layer, shock wave, air jet loom, shuttleless loomAir jet loom isone of the shuttl

5、elessloomswhich Transport a o using frictionalforce ofstring surface and kineticenergy of an air jet.The airjet has a higher performance and wider applications when compared to looms for pro- ducing silks, cotton fabrics, woolen cloth, etc. It is simple in and more eco-n con-ventional looms. The dem

6、and for high-anddoublewidthtoincrease theproductivity callsforhigh-speed and performanceofhas a higher performance and wider applications when compared to looms for pro- ducing silks, cotton fabrics, woolen cloth, etc. It is simple in and more eco-n con-ventional looms. The demand for high-anddouble

7、widthtoincrease theproductivity callsforhigh-speed and performanceofa pickingsystem. Theperformance forthispickingdepends on the ability of instantaneous inhalation/exhaust, configuration of nozzle, operation characteristics of a check valve, etc.In r studies, experimentsforthecharacteristics of flo

8、w fieldin a nozzle the effects of acceleration tube length were performed for design optimization of coaxial air jet loom as ic re on a main nozzle was measured by characteristicsof flow field in a nozzle and the effects of acceleration tube length performed for design optimization of a coaxial air

9、jet loom as ic re on main nozzle was measured by them. ion for optimizing the design transonic flow he air jetloom was conducted, but most of the studies theair jetwere withoil or aStudies for characteristics ic jet flowo an ted with shear layer, and shock wave eraction in a texture nozzle have not

10、been conducted till now. To increase performance of cking system, systematic studies to understand the flow field the main nozzle ofairjet loomsare Though it is desirable to have a uniform area of cross-section throughout length of the acceleration tube, a very small angle of divergence is accelerat

11、ion tube due manufacturing his r, ional study using l FLUENTwas performed to he flow he air jet nozzle of tube very smallamount of divergent angle validated with experimental data k-turbulence his study. The nozzle re ratio from 1.93 to The length of acceleration re to atmospheric re, is defined as

12、the ratio of the nozzlere toatmospheric re, is varied 1.93 to5.8.Thelength of acceleration tubeisvaried from70 mm to110 Figure 1 shows a schematic of the air jet loom.The texture nozzle consists of a nozzle body, anAcceleration tube, and a needle part. The compressed defined as the ratio of the nozz

13、lere toatmospheric re, is varied 1.93 to5.8.Thelength of acceleration tubeisvaried from70 mm to110 Figure 1 shows a schematic of the air jet loom.The texture nozzle consists of a nozzle body, anAcceleration tube, and a needle part. The compressed air through the ody and theacceleration tube, and the

14、n it is o atmosphere. Diameter and of acceleration tube defined as D and The numerical have been carried with the help of .compressible Navier-Stokes equations are discretized spatially using a fully finite volume scheme, in which the io numerical and egral equationsare d to each cell. With temporal

15、terms,.is used discretizethe time shows ernings conditions. length,5.89D includes the nozzle part and downstream flow field of Astructured grid system about 58,000 nodes is considered. Grids areclustered the regions where a large prere gradient is expected like the wall region near shear layer, shea

16、r layer and shock waves. Total temperature is 298K. Adiabatic no-condition is d to nozzle wall, needle wall and acceleration tube. The inlet condition of 588,000 Pa. The total temperature and re outlets at inlet and down stream flowfield condition are chosen as 298 K and 101,325 Pa, ResultandFigure

17、3 shows the comparison of ional results using standard ional results obtained ive agreements with andthe experimental ones. The standard k-have shown ive as well experimental 作者：Heuy-Dong Chae-Min Ho-Joon Lee, Doo-Hwan 388,Songcheon-760-749,2.韓國紡織機(jī)3. 紡織學(xué)院、Yeungnam214作者：Heuy-Dong Chae-Min Ho-Joon Lee

18、, Doo-Hwan 388,Songcheon-760-749,2.韓國紡織機(jī)3. 紡織學(xué)院、Yeungnam214介:可壓縮噴嘴 剪切層 沖擊波 噴氣織機(jī) 無梭織propro 嘴加速管的數(shù)量非常小的發(fā)散角和驗(yàn)證與先前的實(shí)驗(yàn)數(shù)據(jù)可用。這個(gè)軸對(duì) 稱、可壓縮、n-s使用k-方程紊流模型在這研究中使用。噴嘴壓比(NPR),定義為從 70 毫米到 110 毫米。圖 1 顯示了一個(gè)示意圖的噴氣織機(jī)。紋理噴嘴由噴嘴體、加速管和一根針部定義為D 和 L,分別計(jì)算分析數(shù)值模擬進(jìn)行了借助完善的標(biāo)準(zhǔn) k- 模型。這兩個(gè)維度,軸對(duì)稱,維可壓縮 NumericalMethodsfortheFlowFieldThe

19、above can be solved with finite difference method as SIMPLERalgorithmNumericalMethodsfortheFlowFieldThe above can be solved with finite difference method as SIMPLERalgorithm to solve re coupling; roducing staggered to avoid toothlike distributions of velocity and re; er-scheme as the preferred cheme

20、; (4)viscosity and density on are arithmetic mean of neighboring nodes; (5)with TDMA method to solve The is rectangular where the coordinate origin is in middle of the die head. The lengths of x-direction and y-direction of are 150 mm and 30 mm respectively. There are 300 grids in direction and 150g

21、rids inyComparisonofTheoreticalResultswithExperimentalHarpham and Shambaugh did experimental researches on the flow field of the melt blowing die shown in Figure 1. The width of the die h=3.32mm. The l=2.02mm.Theinitial air velocityj0=23.2m/s.The initial airtemperatureThe distributions of the ponent

22、 of air velocity and 度,5.89 d 的高度。結(jié)構(gòu)化網(wǎng)格系統(tǒng)約 58000 節(jié)點(diǎn)被認(rèn)為是。網(wǎng)格都大的壓力梯度地區(qū)預(yù)計(jì)像墻附近地區(qū)剪切層,剪切層和沖擊波?？倻囟?298 k。 條件 588000 Pa。他總 溫度和壓力網(wǎng)點(diǎn)在針進(jìn)口和下游流場(chǎng)條件選為 298 K和101325 Pa,分別。結(jié)果temperature along x-axis are shown in Figure 2 and Figure 3 respectively. There are also curves drawn according to the fitted equations and the

23、experimental data of Harpham and Shambaugh. As can be concluded, the theoretical results obtained the m tallywith theexperimental data The distributions of ponent of temperature along x-axis are shown in Figure 2 and Figure 3 respectively. There are also curves drawn according to the fitted equation

24、s and the experimental data of Harpham and Shambaugh. As can be concluded, the theoretical results obtained the m tallywith theexperimental data The distributions of ponent of air velocity and air temperature y-axis are shown in Figure 4 and Figure 5 respectively. The velocity and profiles of numeri

25、cal simulation are plotted on ition near the ition far from ition below the die die (x=97.5mm). As these three profiles are very near to each other, only one of numerical simulation is drawn on Figure 4 and Figure 5. There are also profiles drawn according to the fitted equations and the experimenta

26、l data of Harpham Shambaugh. As can be concluded, the theoretical results obtained with the coincidentwiththeexperimental datawellWith the aide of Uyttendaele-Shambaugh the effects of the distribution of the velocity on the fiber diameter are erms of both theoretical and using empirical formula of S

27、hambaugh. According to reference, the initial velocity was 25.7m/s. The initial air temperature was 330. The polymer experimental runswas75MFR(meltflowrate)Fina polypropylene. Thepolymermass flow rate was 0.36g/min. The initial polymer temperature was 350. As shown in Figure 6, the two fiber diamete

28、r profiles are almost the same. Therefore, the theoretical approach coincides with the empirical approach he m predictionsof thefiber The numerical simulation of the flow field of dual slot jets in is solved numerically with finite blowing s is founded. The method.The preferred scheme is er-law sche

29、me. And the SIMPLER algorithm is used to re coubling. The distribution of air velocity component in x along x-axis and y-axis and the re coubling. The distribution of air velocity component in x along x-axis and y-axis and the distributions of air air temperature along x-axis y-axis are obtained via

30、 numerical compuion. The compuionresultscoincidewith the experimental data given by Harpham and Shambaugh.The distributions of air velocity and air temperature o the of drag of melt blowing. The o the air drag blowing. The mpredictionofthefiberdiameter agreeswiththeexperimentaldata 1 Harpham A S, Shambaugh R L. Industrial and Engineering Chemistry Research, 1997,36(9),3937-39432 Chen T, Huang X B. Comput