Investigation of the Velocity Field of Jets in Counter-Flow in the Vicinity of a Solid Wall

• Author / Creator

  Mahmoudi, Mohammad

• This study presents experimental investigations showing the mean and fluctuating velocity field of a three dimensional round jet in counter-flow located in the vicinity of a solid wall. The jet to counter-flow velocity ratios ranged from 2.5 to 25 and the jet Reynolds numbers were from 1,000 to 10,000. The ratio of jet centerline distance from the wall over the jet diameter is changed from 0.5 to 4.3. The penetration of the flush mounted jet in counter-flow is measured and compared to the case in which there is no wall available. In addition, the penetration of the jet at various offset distances from the wall is measured and the effect of offset distance is analyzed. The results show that the flush mounted jet has the deepest penetration and as the jet offset distance increases, the penetration decreases to reach the penetration of a free jet in counter-flow. The jet offset distance creates a mechanism that controls the counter-flow entrainment into the jet.
  The jet velocity decay and spreading rate are analyzed and the effect of offset ratio is discussed. It is found that as the offset ratio increases, the jet velocity decays faster and its spreading rate rises. In addition, the amplitude of random oscillations of the flow increases when the distance of the jets from the side wall increases.
  The vortical structures of the flow are studied and their impact on the turbulence characteristics of the flow is explained. Two-point velocity correlation study shows that the size of turbulent structures of the flow becomes larger as the jet offset ratio increases. Also, the turbulent transport in the flow enhances dramatically as the jet gets higher distance from the side wall.

• Subjects / Keywords

  • Wall Jet
  • Counter-Flow
  • Velocity Field
  • Offset Jet

• Graduation date

  Fall 2015

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R34B2XD0V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.