This paper presents an investigation into the effect of propeller-induced flow on axial velocity under static and dynamic conditions, as well as the axial mean velocity of propeller-induced flow influenced by underwater vegetation. The study utilised both side-look and down-look probes for Acoustic Doppler Velocimeter (ADV) measurements. The results revealed that the axial velocity profile can be characterised by a Gaussian normal probability function. The flow pattern behind a submerged jet can be divided into two zones: the zone of flow establishment (ZFE), immediately downstream of a propeller orifice, and the zone of established flow (ZEF). The length of the ZFE was found to be \(X/D_{p} \, = \,2.14\) in both tests, where X is the axial distance from the propeller to the downstream and \(D_{p}\) is the diameter of the propeller. Fuehrer et al. (Propeller jet erosion and stability criteria for bottom protections of various constructions in 1987 [4]) equation for efflux velocity \(\left( {U_{o} } \right)\) was applied for both conditions with a difference from the measured value of no more than 0.5%. In investigating vegetation's effect, the static condition revealed a negligible effect on vegetation for both the above and crossed propeller positions at 300 and 1000 rpm. However, under dynamic conditions, the vegetation effect was evident in both positions. It revealed that the water flow from the propeller, shaped conically, is not significantly affected by vegetation, whereas the straight water flow in the flume is influenced by vegetation. To advance this investigation further, my research will analyse transverse and radial velocity, turbulent intensity, and Reynolds stress. Quadrant analysis will also be employed to achieve a better understanding of flow characteristics.

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Investigation of Propeller-Induced Flow with Influence of Under-Water Vegetated Field

  • Heba Mals,
  • Jaan H. Pu,
  • Amir Khan

摘要

This paper presents an investigation into the effect of propeller-induced flow on axial velocity under static and dynamic conditions, as well as the axial mean velocity of propeller-induced flow influenced by underwater vegetation. The study utilised both side-look and down-look probes for Acoustic Doppler Velocimeter (ADV) measurements. The results revealed that the axial velocity profile can be characterised by a Gaussian normal probability function. The flow pattern behind a submerged jet can be divided into two zones: the zone of flow establishment (ZFE), immediately downstream of a propeller orifice, and the zone of established flow (ZEF). The length of the ZFE was found to be \(X/D_{p} \, = \,2.14\) in both tests, where X is the axial distance from the propeller to the downstream and \(D_{p}\) is the diameter of the propeller. Fuehrer et al. (Propeller jet erosion and stability criteria for bottom protections of various constructions in 1987 [4]) equation for efflux velocity \(\left( {U_{o} } \right)\) was applied for both conditions with a difference from the measured value of no more than 0.5%. In investigating vegetation's effect, the static condition revealed a negligible effect on vegetation for both the above and crossed propeller positions at 300 and 1000 rpm. However, under dynamic conditions, the vegetation effect was evident in both positions. It revealed that the water flow from the propeller, shaped conically, is not significantly affected by vegetation, whereas the straight water flow in the flume is influenced by vegetation. To advance this investigation further, my research will analyse transverse and radial velocity, turbulent intensity, and Reynolds stress. Quadrant analysis will also be employed to achieve a better understanding of flow characteristics.