air jet weaving
Post on 15-Sep-2015
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Textile Machines Research Institute Liberec
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Fluid mechanics applications in textile machineryKarel Admek
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Air jet weft pickingSchematicsMain nozzleRelay nozzleStretching nozzleSuction nozzlePicking channelReed dentsFriction influence braking nozzleU-loop pickingPneumatic picking + beat-upYarn-flow interaction
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Principle of air jet weft pickingMain nozzle relay nozzles stretching + suction nozle
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Main nozzlesInfluence of mixing tube shape on velocity field (cylindrical stepped divergent)
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Relay nozzlesHydraulic analogy
Channel relay jet
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Stretching nozzleSimple cornered shape (left) gives much higher noise level (because of flow separation, vortexes, backflow...)
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Suction nozzlePrinciple of wall effect very simple design, very silent, economic and reliable operation
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Flowfield along the reed wallInteraction of free flow with reed wall Interactions of mutual interactions of several free flows
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Reed dentsStudy of influences of various reed wall parameters on flowfield image(wall filling, shape of dent edges, angle of attack)
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Total quantity of motion in reed channellThe most part of momentum supplied from nozzle is flowing outside channel (theoretical values without flow reflection by reed dents etc.)
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Reed channel - cross sectionInfluence of nozzle setting and adjjusting on total quantity of motion in reed channel
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Y-shaped reed channel - geometry
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Braking nozzleDesign Flat cross-section of velocity field from nozzle outlet
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Weft picking as U-loopAir jet picking of very heavy wefts - modelling verification of hypothesis
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Pneumatic picking + beat-up (principle)Velocity field of picking phase (up) and transition phase between picking and beat-up (down) modelling of hypothesis
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Other applications of numerical flow modelling in textile machines / technologies
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Air flow in carding clothingFlow during rotation (40 m/s)drum diameter of 1200 mm, dent height 1 mm approx.
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Ait flow in common suction channel(open-end spinning machine)Global flowfield and its detail
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Technology melt-blown(velocity field)Production of very fine fibre fleece from melted polymer
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Difusser of gas burner(for glass fibre production) Former shape with flow separation
New shape without flow separation
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Increasing of drying process intensityDesign modification improves the heat transfer and steam escape together with noise level reduction
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Flow paths in impact dryerAir inlet and outlet in proximity of dried (bottom) surface - difficult steam effluent
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Cloth permeabilityPressure field on surface of complicated cloth structure
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Make drying before painting unsuitable primary design
more intense modification
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Noise level of blow gunPressure field of open gun (up) and with strainer (down)
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Gas burnerFlow paths in one section of rod burner
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Velocity field around rotating drumsFlowfield in system of printing machine
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Surface temperature of heat exchangerLocal overheating of heat transfer surface
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Air curtainCurtain air flow separates cold surroundings (left) and warm inner space (right)
*Pneumatic weft pickingbytek hybnosti transportnho proudu, zpsoben pirozenou disipac proudu z hlavn trysky (navren jako ejektor) je doplovn soustavou pomocnch trysek podl kanlu.*Hlavn body prezentace pehled nkterch zajmavch poznatk.*Numerick model jednoho resp. vce proud podl lamelov stny v kadm mst je jin vektor dopadajcho proudu, inky jednotlivch trysek se vzjemn ovlivuj. Modelovn zatek bez hlavn trysky, po 5-6 roztech je dosaeno ustlenho periodickho stavu.*Vznamn vliv na propustnost a odrazivost lamelov stny m t zaplnn stny, tvar hran atd. (modelovn stl hel nabhajcho proudu)*Idealizovan prnik kanlu ve tvaru plvlce s kuelovm proudem, znme rozloen hybnosti v kuelovm proudu.Vtina hybnosti jde mimo kanl.Skutenost je mrn lep, vlivem lamelov stny kanlu se st proudu odr zpt do kanlu.*Hypotza jin polohy kanlu, aby se zabrnilo vypadvn tku z kanlu pi transportu*Schma systmu s pneumatickm prohozem (nahoe) i prazem (dole) i mechanick praz je nahrazen inkem proud vzduchu
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