Proceedings of the Thirty-second (2022) International Ocean and Polar Engineering Conference
Shanghai, China, June 5–10, 2022
Copyright © 2022 by the International Society of Offshore and Polar Engineers (ISOPE)
ISBN 978-1-880653-81-4; ISSN 1098-6189

www.isope.org

Experimental study on the Effect of Location of Air Bubble Curtain on Turbulence Flow around Moving
Ship
Qidi Gao1, Jinshu Lu1, Peng Xu1
1: School of Naval Architecture and Maritime, Zhejiang Ocean University, Zhoushan, Zhejiang, China

ABSTRACT

new standards. The most direct way to reduce ship emissions is to reduceship resistance in the process of moving, thereby reducing fuelIn this paper, turbulence suppression, one of the drag reduction

consumption. It is difficult to break through the traditional drag reduction

mechanisms of air curtain, is experimentally studied.In the experiment,

methods such as optimizing the ship ' s fluid shape, drag reduction

PIV ( Particle Image Velocimetry) was used to conduct the air curtain

structure and surface materials. Therefore, the air curtain drag reduction

drag reduction experiment on the plate in the circulating water tank.

method has become a feasible way to reduce ship resistance in the future.

Under different flow velocities, the transition position from laminar flow

The theory of air curtain drag reduction has a long history. The earliest

to turbulent flow is different on the surface of the plate. In a certain area

experiment produced bubbles by electrolysing water on the surface of

before and after the transition position, bubbles are injected to form air

the rotary body, which formed a bubble layer on the surface of the rotary

curtain and the influence of air curtain on turbulent flow is observed. At

body and reduced the surface friction resistance (Michael, et al ,1973).

the same time, the resistance of the plate is measured by the force sensor.

The experiment proves that adding air curtain on the surface of the object

By changing the injection position, the best drag reduction effect is

can reduce the resistance. And it is proposed that bubbles increase theobtained. The turbulent flow field of the jet position with the best dragthickness of laminar boundary layer; destroying the subsurface;

reduction effect is analyzed. It is proved that the suppression ofconjecture of changing momentum transport in turbulent layers to reduceturbulence by air curtain can reduce the surface friction resistance of thesurface friction resistance. (Madavan, et al ,1984) A special plate device

plate, and the suppression effect of different jet positions on turbulence

was made and carried out experiments in a circulating water tank. Theis different. Reasonable air curtain position can effectively suppress

results showed that the optimal drag reduction effect could reach about

turbulent flow, so as to achieve the best drag reduction effect.

80 %. Due to the influence of buoyancy, the drag reduction effect of thelower surface of the plate was better than that of the upper surface. SoKEY WORDS: Air Curtain Drag Reduction; Plate Experiment;

far there are some mainstream speculations about the mechanism of air

Turbulence Suppression; Flow Field Analysis.

curtain drag reduction. A two-dimensional model was used to calculate
the microbubble model on the plate. Through the comparison ofINTRODUCTION

experiment and numerical simulation, it was proved that the decrease of
the mixed fluid density led to the decrease of the friction resistanceDue to the growing awareness of environmental protection worldwide,(Skudarnov, et al ,2006). The drag reduction is caused by the change ofenergy conservation and emission reduction have become a hot topic. As

effective viscosity in laminar boundary due to the decrease of density ofthe main form of freight transportation, the emissions of the shipping

mixed fluid (MARIE, 1987) and (Lvov et al, 2005). The formation andindustry account for a large proportion of the total emissions. In the facemovement characteristics of bubbles in drag reduction were observed byof increasingly stringent emission limitation policies, new theories andexperiments. The drag reduction effect of bubbles in residence depends

technologies are urgently needed to reduce ship emissions to adapt toon the porosity near the wall (Janssen, et al ,1984). The coalescence and3449