Experimental investigation on the flow characteristics of three-dimensional turbulent offset jets
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Date
2015-05-08, 2015-12-24, 2016-07-04, 2016-08-26
Authors
Nyantekyi-Kwakye, Baafour
Journal Title
Journal ISSN
Volume Title
Publisher
Taylor and Francis Group
Abstract
An experimental study was designed to investigate the effect of different parameters on the development and structure of turbulent 3D offset jets. The present investigation considered the effects of offset height ratio, expansion ratio, surface roughness and rib placement on the flow dynamics of a turbulent 3D offset jet. The velocity measurements were performed using an acoustic Doppler velocimetry (ADV) and particle image velocimetry (PIV). Measurements were conducted within the symmetry and lateral planes. For the PIV technique, the measurements in the symmetry and lateral planes were conducted over a streamwise range of 0 ≤ x/bo ≤ 80 and 12 ≤ x/bo ≤ 60, respectively (where bo is the nozzle height). Likewise, velocity measurements using the ADV technique were conducted over a range of 4 ≤ x/bo ≤ 45 in both the symmetry and lateral planes. The velocity measurements were analyzed using both one-point and multi-point statistics. The one-point statistics included profiles of the mean velocities, Reynolds stresses and some of the budget terms in the turbulent kinetic energy transport equation. The quadrant analysis technique was used to investigate the dominant events that contribute towards the Reynolds shear stress. The two-point correlation analysis was used to investigate how the turbulence quantities are correlated. Information obtained from the two-point correlation analysis was also used to investigate the inclination of vortical structures within the inner and outer shear layers of the 3D offset jet. The direction of the positive mean shear gradient played an active role in the inclination of these vortical structures within the inner and outer shear layers. The reattachment process resulted in the breakdown of these structures within the developing region. Similarly, various length scales were estimated from these structures. The proper orthogonal decomposition was used to examine the distribution of the turbulent kinetic energy within the offset jet flow. Also, the dynamic role of the large scale structures towards the turbulent intensities, turbulent kinetic energy and Reynolds shear stress was investigated.
Description
Keywords
Acoustic Doppler velocimeter, Particle image velocimeter, Three-dimensional, Offset jet, Proper orthogonal decomposition, Two-point correlation, Surface mounted rib, Surface roughness, Nozzle expansion ratio
Citation
Flow characteristics within the recirculation region of three-dimensional turbulent offset jet Nyantekyi-Kwakye, B., Clark, S. P., Tachie, M. F., Malenchak, J., & Muluye, G. (2015). Flow characteristics within the recirculation region of three-dimensional turbulent offset jet. Journal of Hydraulic Research, 53(2), 230-242.
Experimental study of the flow structures of 3D turbulent offset jets Nyantekyi-Kwakye, B., Tachie, M. F., Clark, S. P., Malenchak, J., & Muluye, G. Y. (2015). Experimental study of the flow structures of 3D turbulent offset jets. Journal of Hydraulic Research, 53(6), 773-786.
Flow Characteristics of an Offset Jet over a Surface Mounted Square Rib Nyantekyi-Kwakye, B., Tachie, M. F., & Clark, S. P. (2016). Flow characteristics of an offset jet over a surface mounted square rib. Journal of Turbulence, 17(8), 727-757.
Acoustic Doppler Velocimeter Measurements of a Submerged Three-Dimensional Offset Jet Flow over Rough Surfaces Nyantekyi-Kwakye, B., Tachie, M. F., Clark, S. P., Malenchak, J., & Muluye, G. (2016). Journal of Hydraulic Research, doi: 10.1080/00221686.2016.1212413
Experimental study of the flow structures of 3D turbulent offset jets Nyantekyi-Kwakye, B., Tachie, M. F., Clark, S. P., Malenchak, J., & Muluye, G. Y. (2015). Experimental study of the flow structures of 3D turbulent offset jets. Journal of Hydraulic Research, 53(6), 773-786.
Flow Characteristics of an Offset Jet over a Surface Mounted Square Rib Nyantekyi-Kwakye, B., Tachie, M. F., & Clark, S. P. (2016). Flow characteristics of an offset jet over a surface mounted square rib. Journal of Turbulence, 17(8), 727-757.
Acoustic Doppler Velocimeter Measurements of a Submerged Three-Dimensional Offset Jet Flow over Rough Surfaces Nyantekyi-Kwakye, B., Tachie, M. F., Clark, S. P., Malenchak, J., & Muluye, G. (2016). Journal of Hydraulic Research, doi: 10.1080/00221686.2016.1212413