Penetration of pulp-fibre suspension jet
Ojala, Eetu (2017)
2017
Ympäristö- ja energiatekniikan koulutusohjelma
Teknis-luonnontieteellinen tiedekunta - Faculty of Natural Sciences
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Hyväksymispäivämäärä
2017-01-11
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201612224908
https://urn.fi/URN:NBN:fi:tty-201612224908
Tiivistelmä
Manufacturing pulp and paper products is energy-intensive. A better understanding of flow behaviour of pulp-fibre suspension is essential for improving the efficiency of unit processes in pulp and paper industry. Computational fluid dynamics (CFD) offers a powerful tool for simulating the flow of pulp-fibre suspension in industrial processes. There is, however, a lack of experimental research on turbulent flow of pulp-fibre suspension for validation purposes.
The objective of this thesis is to present a new experimental method for measuring a flow field of turbulent pulp-fibre suspension wall jet. In order to validate the CFD simulation approach used in this work, the measurements were compared with the results obtained from CFD simulations. A novel experimental jet chamber was designed and built in Tampere University of Technology to measure the opening angle and penetration depth of pulp-fibre suspension jet discharging from a round pipe next to a wall. Photography was used to visually measure the jet spread and penetration depth, while Pulsed Ultrasound Doppler Velocimetry (PUDV) was used to obtain the velocity profile of the jet.
Open-source CFD toolbox OpenFOAM was used to simulate the flow field inside the jet chamber. The simulation basis consisted of combining a non-Newtonian Herschel-Bulkley material model with the k −ω SST turbulence model. Material model parameters used in the simulations were obtained from a previous research work conducted at Tampere University of Technology. The simulations showed a reasonable agreement with the photographic measurements, but there was a significant deviation with the measured and simulated velocity profiles, especially in high fibre consistencies.
The simulation approach used in this work can be used to model general flow properties of pulp-fibre suspension in process equipment with acceptable accuracy.
The objective of this thesis is to present a new experimental method for measuring a flow field of turbulent pulp-fibre suspension wall jet. In order to validate the CFD simulation approach used in this work, the measurements were compared with the results obtained from CFD simulations. A novel experimental jet chamber was designed and built in Tampere University of Technology to measure the opening angle and penetration depth of pulp-fibre suspension jet discharging from a round pipe next to a wall. Photography was used to visually measure the jet spread and penetration depth, while Pulsed Ultrasound Doppler Velocimetry (PUDV) was used to obtain the velocity profile of the jet.
Open-source CFD toolbox OpenFOAM was used to simulate the flow field inside the jet chamber. The simulation basis consisted of combining a non-Newtonian Herschel-Bulkley material model with the k −ω SST turbulence model. Material model parameters used in the simulations were obtained from a previous research work conducted at Tampere University of Technology. The simulations showed a reasonable agreement with the photographic measurements, but there was a significant deviation with the measured and simulated velocity profiles, especially in high fibre consistencies.
The simulation approach used in this work can be used to model general flow properties of pulp-fibre suspension in process equipment with acceptable accuracy.