Textile Machines Research Institute Liberec

Fluid mechanics applications in textile machineryKarel Admek

Air jet weft pickingSchematicsMain nozzleRelay nozzleStretching nozzleSuction nozzlePicking channelReed dentsFriction influence braking nozzleU-loop pickingPneumatic picking + beat-upYarn-flow interaction

Principle of air jet weft pickingMain nozzle relay nozzles stretching + suction nozle

Main nozzlesInfluence of mixing tube shape on velocity field (cylindrical stepped divergent)

Relay nozzlesHydraulic analogy

Channel relay jet

Stretching nozzleSimple cornered shape (left) gives much higher noise level (because of flow separation, vortexes, backflow...)

Suction nozzlePrinciple of wall effect very simple design, very silent, economic and reliable operation

Flowfield along the reed wallInteraction of free flow with reed wall Interactions of mutual interactions of several free flows

Reed dentsStudy of influences of various reed wall parameters on flowfield image(wall filling, shape of dent edges, angle of attack)

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.)

Reed channel - cross sectionInfluence of nozzle setting and adjjusting on total quantity of motion in reed channel

Y-shaped reed channel - geometry

Braking nozzleDesign Flat cross-section of velocity field from nozzle outlet

Weft picking as U-loopAir jet picking of very heavy wefts - modelling verification of hypothesis

Pneumatic picking + beat-up (principle)Velocity field of picking phase (up) and transition phase between picking and beat-up (down) modelling of hypothesis

Other applications of numerical flow modelling in textile machines / technologies

Air flow in carding clothingFlow during rotation (40 m/s)drum diameter of 1200 mm, dent height 1 mm approx.

Ait flow in common suction channel(open-end spinning machine)Global flowfield and its detail

Technology melt-blown(velocity field)Production of very fine fibre fleece from melted polymer

Difusser of gas burner(for glass fibre production) Former shape with flow separation

New shape without flow separation

Increasing of drying process intensityDesign modification improves the heat transfer and steam escape together with noise level reduction

Flow paths in impact dryerAir inlet and outlet in proximity of dried (bottom) surface - difficult steam effluent

Cloth permeabilityPressure field on surface of complicated cloth structure

Make drying before painting unsuitable primary design

more intense modification

Noise level of blow gunPressure field of open gun (up) and with strainer (down)

Gas burnerFlow paths in one section of rod burner

Velocity field around rotating drumsFlowfield in system of printing machine

Surface temperature of heat exchangerLocal overheating of heat transfer surface

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