Towed cable behaviour during ship turning manoeuvers

Chapman, Darren

doi:10.1016/0029-8018(84)90010-6

Cited by 41 publications

(16 citation statements)

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“…The sensor array and cables are designed to withstand harsh marine environment and hydrodynamic forces experienced due to waves and currents during operation. Nevertheless, previous sea trial experiences have shown that the strength member terminations in the tow cable and array are vulnerable to failuredue to dynamic loading during deployment & retrieval operations, see Chapman (1984).Then the sensor array being negatively buoyant, will sink to sea-bottom and is irretrievable, see Dowling (1988). There may also be situations where ship's engine can get stopped suddenly while towing the array, resulting in sinking of array and cable to depths higher than allowable.…”

Section: Introductionmentioning

confidence: 95%

Design and Development of Depth Activated Inflatable Recovery System for Undersea Towed Sensor Arrays

et al. 2015

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A typical towed sensor arraywet-end system consists of electro optic-mechanical tow cables, active transmitter unit and towed sensor array modules followed by a tail rope at the aft-end. The sensor array and cables are designed to withstand harsh marine environment and hydrodynamic forces experienced due to waves and currents during operation. Nevertheless, the strength member termination in the tow cable and array are vulnerable to failure due to dynamic loading during repeated deployment and retrieval operations.To prevent the loss of cable and array in such cases, a recovery system is required. In this paper, the design of a Depth Activated Inflatable Recovery System for undersea towed sensor arrays is presented. The envisaged system is a cylindrical, flexible module with similar diameter as the sensor array module and maximum length of 10 m which can be mechanically attached to the aft-end of the towed array. The system consists of a pressure switch, which gets activated as the detached array sinks and reaches a pre-set depth of 250 m. This completes an electrical circuit connected to a power source through which high current passes to an electro-explosive pyro-cartridge and activates it. This generates enough force to push a piston mechanism which punctures a CO 2 cylinder. The CO 2 gas fills into an inflatable bag. Multiple numbers of such inflatable bags, when opened, will provide sufficient buoyancy for array to move up to the surface. The paper discusses the design methodology, development, assembly and testing of various sub-systems, challenges faced and innovative solutions implemented for realizing an effective Recovery System.

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Section: Introductionmentioning

confidence: 95%

Design and Development of Depth Activated Inflatable Recovery System for Undersea Towed Sensor Arrays

et al. 2015

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“…This work will extend the analysis of Chapman (1984) to include transient effects due to currents, waves, and the inertia of the tow-cable system. We expect that a complete parametric analysis will lead to the redefinition of the critical turn radius and provide a mapping of stability boundaries between large-radius turn behavior (where the configuration is a perturbation of the straight-line towing solution) and small-radius turn behavior (where the cable configuration undergoes a rapid collapse with an accompanying rapid increase in the tension).…”

Section: Objectivesmentioning

confidence: 99%

“…This replaces the boxmethod scheme, which is used in Ablow & Schechter (1983) and which can lead to Crank-Nicholson errors in the solution. The initial set of simulations will be carried out with similar assumptions regarding the dynamics of the tow ship and towed vehicle as used by Chapman (1984). That is the tow ship is assumed to be unaffected by the cable dynamics, and the towed vehicle's weight, inertia and drag are assumed to act at the end point of the tow cable.…”

Section: Approachmentioning

confidence: 99%

“…The towed array results were incorporated into a manuscript about the WHOI Cable numerical scheme, which was submitted this year and is now in press (Gobat and Grosenbaugh, 2005). We are preparing a new manuscript on simulation results of towed vehicles undergoing circular maneuvers and the comparison with previous studies (Chapman, 1984). We continue to work on incorporating VIVA software into WHOI Cable so that we can calculate the normal drag coefficient as a function of instantaneous vibration amplitude.…”

Section: Work Completedmentioning

confidence: 99%

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Dynamic Behavior of Towed Cable Systems During Ship Turning Maneuvers

Grosenbaugh¹

2005

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The long-term goal is to develop a framework for controlling towed vehicles through a combination of ship maneuvers and active control devices on the towed vehicle. Typical usage of a towed reconnaissance system involves towing a vehicle with acoustic and optical sensors back and forth over a search area along parallel track lines. At the end of each track line, the vehicle executes a 180-degree turn so that it ends up on a new track line and at a specified towing depth. In some cases, the towing depth is varied with time depending on the ocean bottom topography. How best to optimize the towing strategy for a particular set of track lines is still an open question. OBJECTIVESOur objective is to analyze the dynamics of a towed cable-vehicle system during ship turning maneuvers. This work will extend the analysis of Chapman (1984) to include transient effects due to currents, waves, and the inertia of the tow-cable system. We expect that a complete parametric analysis will lead to the redefinition of the critical turn radius and provide a mapping of stability boundaries between large-radius turn behavior (where the configuration is a perturbation of the straight-line towing solution) and small-radius turn behavior (where the cable configuration undergoes a rapid collapse with an accompanying rapid increase in the tension). The parametric analysis will include the effects of time varying vortex-induced vibrations and active control of the towed vehicle.

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“…Several types of analytical and numerical models have been developed. Lumped mass models, where the string is spatially discretized into connected point masses, are developed in [1][2][3][4]. Finite difference methods in both the spatial domain and the time domain are applied in [5,6].…”

Section: Introductionmentioning

confidence: 99%

Computational dynamics of a 3D elastic string pendulum attached to a rigid body and an inertially fixed reel mechanism

2010

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A high fidelity model is developed for an elastic string pendulum, one end of which is attached to a rigid body while the other end is attached to an inertially fixed reel mechanism which allows the unstretched length of the string to be dynamically varied. The string is assumed to have distributed mass and elasticity that permits axial deformations. The rigid body is attached to the string at an arbitrary point, and the resulting string pendulum system exhibits nontrivial coupling between the elastic wave propagation in the string and the rigid body dynamics. Variational methods are used to develop coupled ordinary and partial differential equations of motion. Computational methods, referred to as Lie group variational integrators, are then developed, based on a finite element approximation and the use of variational methods in a discrete-time setting to obtain discrete-time equations of motion. This approach preserves the geometry of the configurations, and leads to accurate and efficient algorithms that have guaranteed accuracy properties that make them suitable for many dynamic simulations, especially over long simulation times. Numerical results are presented for typical examples involving a constant length string, string deployment, and string retrieval. These demonstrate the complicated dynamics that arise in a string pendulum from the interaction of the rigid body motion, elastic wave dynamics in the string, and the disturbances introduced by the reeling mechanism. Such interactions are dynamically important in many engineering problems, but tend be obscured in lower fidelity models.

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Towed cable behaviour during ship turning manoeuvers

Cited by 41 publications

References 1 publication

Design and Development of Depth Activated Inflatable Recovery System for Undersea Towed Sensor Arrays

Design and Development of Depth Activated Inflatable Recovery System for Undersea Towed Sensor Arrays

Dynamic Behavior of Towed Cable Systems During Ship Turning Maneuvers

Computational dynamics of a 3D elastic string pendulum attached to a rigid body and an inertially fixed reel mechanism

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