Snmek 1

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Textile Machines Research Institute Liberec
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Fluid mechanics applications in textile machinery

• Karel Adámek

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Air jet weft picking

• Schematics
• Main nozzle
• Relay nozzle
• Stretching nozzle
• Suction nozzle
• Picking channel
• Reed dents

• Friction influence braking nozzle
• U-loop picking
• Pneumatic picking beat-up
• Yarn-flow interaction

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Principle of air jet weft picking
Main nozzle relay nozzles
stretching suction nozle
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Main nozzles
Influence of mixing tube shape on velocity field
(cylindrical stepped divergent)
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Relay nozzles
Hydraulic analogy ? Channel relay jet ?
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Stretching nozzle
Simple cornered shape (left) gives much higher
noise level (because of flow separation,
vortexes, backflow...)
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Suction nozzle
Principle of wall effect very simple design,
very silent, economic and reliable operation
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Flowfield along the reed wall
Interaction of free flow with reed wall
Interactions of mutual interactions of several
free flows
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Reed dents
Study 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 channell

• The 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 section
Influence 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 nozzle
Design Flat cross-section of velocity field from
nozzle outlet
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Weft picking as U-loop
Air 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 clothing
Flow 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 intensity
Design modification improves the heat transfer
and steam escape together with noise level
reduction
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Flow paths in impact dryer
Air inlet and outlet in proximity of dried
(bottom) surface - difficult steam effluent
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Cloth permeability
Pressure 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 gun
Pressure field of open gun (up) and with strainer
(down)
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Gas burner
Flow paths in one section of rod burner
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Velocity field around rotating drums
Flowfield in system of printing machine
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Surface temperature of heat exchanger
Local overheating of heat transfer surface
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Air curtain
Curtain air flow separates cold surroundings
(left) and warm inner space (right)