Aspects of the measurement of the acoustic transfer function in a cavitation tunnel     

《Applied Ocean Research》2019

Model scale experiments represent one of the most effective, and probably the most commonly used, approaches for the study of cavitating propeller noise. Despite this, the acquirement of consistent data of propeller noise from tests in model scale facilities is still a challenging task. Data collected with such an approach are usually affected by several scale effects and facility related issues which make such experiments still very complex. Among others, the effect of the facility itself as acoustical surrounding must be carefully addressed in order to properly estimate propeller source levels in ideal free field conditions. This is currently carried out, when possible, by measuring facility transfer functions and applying such functions as a correction to measured noise spectra. The development of robust procedures for the measurement of these transfer functions is thus very important. In the present work, this problem is addressed by discussing in details techniques, merits and possible problems related to this topic.  相似文献   

On the determination of the mesh size for numerical simulations of shock wave propagation in near field underwater explosion     

《Applied Ocean Research》2016

It is well known that the accuracy of mesh-based numerical simulations of underwater explosion strongly relies on the mesh size adopted in the analyses. Although a numerical analysis of underwater explosion can be performed with enough accuracy by using considerably fine meshes, such fine meshes may lead to substantially increase in the CPU time and the usage of computer memory. Thus, how to determine a suitable mesh size in numerical simulations is always a problem confronted when attempting to study the shock wave propagation resulting from underwater explosion and the subsequent response of structures. Considering that there is currently no universally accepted method for resolving this problem, this paper aims to propose a simple method to determine the mesh size for numerical simulations of near field underwater explosion. To this end, the mesh size effects on the shock wave propagation of underwater explosion are carefully investigated for different charge weights, through which the correlation between mesh sizes and charge weights is identified. Based on the numerical study, a dimensionless variable (λ), defined as the ratio of the radius of charge to the side length of element, is introduced to be the criterion for determining the mesh size in simulations. It is interesting to note that the presented method is suitable for various charge weights. By using the proposed meshing rule, adequate balance between solution accuracy and computational efficiency can be achieved for different blast scenarios in numerical simulations of underwater explosion.  相似文献   

Fish are attracted to vessels   总被引：1，自引：0，他引：1  

Rostad  Anders; Kaartvedt  Stein; Klevjer  Thor A.; Melle  Webjorn 《ICES Journal of Marine Science》2006,63(8):1431-1437

  相似文献   

A consistent approach to definitions and symbols in fisheries acoustics   总被引：7，自引：17，他引：7  

Maclennan  David N.; Fernandes  Paul G.; Dalen  John 《ICES Journal of Marine Science》2002,59(2):365-369

  相似文献   

Study of a jet-propulsion method for an underwater vehicle   总被引：1，自引：0，他引：1  

Umesh A. Korde 《Ocean Engineering》2004,31(10):1205-1218

This paper investigates a novel jet-propulsion method for a submerged vehicle. The approach is based on flexible-tube, eccentric rotor, Downingtown-Huber type pumps. Equations of motion are derived for a craft driven by such pumps. In order to develop general insight into the overall dynamics of the system, simulations are carried out for the simple case of horizontal straight-line motion. Results are obtained for the vehicle velocity, distance traveled, pump speed, and energy consumption. Effect of drag forces on the operation of the craft is studied. Finally, the jet-propulsion system is compared with conventional screw-type propulsors via simulation.  相似文献   

An alternative echo-integrating method     

Aksland  Magnar 《ICES Journal of Marine Science》2005,62(2):226-235

  相似文献   

Fish detection by the acoustic scintillation technique     

Ye  Zhen; Curran  Terry; Lemon  David 《ICES Journal of Marine Science》1996,53(2):317-321

  相似文献   

海底沉积物声衰减研究现状及展望   总被引：4，自引：0，他引：4  

刘强  卢博 《海洋技术学报》2006,25(2):63-66,111

根据近年来海底沉积物声学物理研究发展的态势,介绍了与研究声衰减有关的海底沉积物样品采集装置和海洋沉积物声速结构模式,综合解析多种对海底沉积物声衰减等声学特性研究方法,并做出较为详细地比较和讨论,提出对海底沉积物声衰减研究在满足科研要求的同时也应符合国家标准和要求。同时,指出了研究海洋沉积物声衰减的必要性和重要性,强调了对海底沉积物声衰减研究的科学意义和应用意义。  相似文献   

Diel variation in acoustic density measurements of overwintering herring (Clupea harengus L.)     

Huse  Ingvar; Korneliussen  Rolf 《ICES Journal of Marine Science》2000,57(4):903-910

  相似文献   

Characterizing uncertainty in target-strength measurements of a deepwater fish: orange roughy (Hoplostethus atlanticus)     

Kloser  R.J; Horne  J.K 《ICES Journal of Marine Science》2003,60(3):516-523

  相似文献