A constant-depth ichthyoplankton sampler is vital equipment for monitoring fish recruitment and assessing fishery stocks.Its depressor,a critical component,maintains towing stability during sampling by balancing the s...A constant-depth ichthyoplankton sampler is vital equipment for monitoring fish recruitment and assessing fishery stocks.Its depressor,a critical component,maintains towing stability during sampling by balancing the sinking force of the depressor and the drag force of the sampler.Conventional depressors often fail to maintain this equilibrium due to their limited sinking force.This study proposes a biplane depressor,inspired by the aerodynamics of biplane hyper-lift trawl doors.In the hydrodynamic experiment,the maximum sinking force coefficient for the proposed biplane depressor with a stagger angle of 30◦reached 2.02,which was significantly higher than that for conventional depressors(less than 1.60).Moreover,substituting metal with canvas for 40%of the wing area reduced the weight without compromising sinking performance(maximum sinking force coefficient:1.86).A towing experiment demonstrated a consistent sinking force and towing stability for the depressor with and without canvas.Operating angles of attack of 27°and 23°are recommended for the depressor made of all metal and a combination of metal and canvas,respectively.The results indicate the potential of the proposed biplane depressor to replace conventional depressors to enhance the constant-depth performance of the sampler and ensure reliable sample collection for ichthyoplankton surveys.展开更多
基金financially supported by the National Natural Science Foundation of China under Grant No.32202997the project ZR2022QD010 supported by Shandong Provincial Natural Science Foundation.
文摘A constant-depth ichthyoplankton sampler is vital equipment for monitoring fish recruitment and assessing fishery stocks.Its depressor,a critical component,maintains towing stability during sampling by balancing the sinking force of the depressor and the drag force of the sampler.Conventional depressors often fail to maintain this equilibrium due to their limited sinking force.This study proposes a biplane depressor,inspired by the aerodynamics of biplane hyper-lift trawl doors.In the hydrodynamic experiment,the maximum sinking force coefficient for the proposed biplane depressor with a stagger angle of 30◦reached 2.02,which was significantly higher than that for conventional depressors(less than 1.60).Moreover,substituting metal with canvas for 40%of the wing area reduced the weight without compromising sinking performance(maximum sinking force coefficient:1.86).A towing experiment demonstrated a consistent sinking force and towing stability for the depressor with and without canvas.Operating angles of attack of 27°and 23°are recommended for the depressor made of all metal and a combination of metal and canvas,respectively.The results indicate the potential of the proposed biplane depressor to replace conventional depressors to enhance the constant-depth performance of the sampler and ensure reliable sample collection for ichthyoplankton surveys.
