Introduction

Renilson, Martin

doi:10.1007/978-3-319-16184-6_1

Cited by 6 publications

(11 citation statements)

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“…The pitching amplitude (width of the depth overshoot) was found to be larger for the case of the faster sailing speed and varied according to different periods of the stern plane operations. For U = 0.5, 1, and 1.5 m/s, the pitching amplitudes are 0.44, 0.48, and 1.14 m. The SFRM moved significantly farther at higher speeds, and a slight pitch motion occurred due to the movement of the critical point [35]. In addition, the simulated trajectories and time between stern plane position changes varied at different sailing speeds.…”

Section: Vertical Zigzag Testmentioning

confidence: 96%

“…Definitely, it is crucial to determine whether the ballast tanks and the attitude adjusting system are available to estimate the variation of SFRM's mass and the longitudinal CG. According to the procedure [35], the effects of the ballast tanks and the attitude adjusting system can be plotted as a function of mass and trimming moment as follows: 0…”

Section: Trim Polygonmentioning

confidence: 99%

“…Figure 12 compares the trajectories of the simulated SFRM at three sailing speeds: U = 0.5, 1, and 1.5 m/s. It is clearly found that the straight parts of these three trajectories are not coincident due to the variation of the critical point [35], which will affect the pitch angle and the straight-line stability. When executing the turning circle tests, the advances of the SFRM are 44.8, 95, and 145.6 m, corresponding to three sailing speeds, i.e., U = 0.5, 1, and 1.5 m/s.…”

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confidence: 99%

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Stability and Manoeuvrability Simulation of a Semi-Autonomous Submarine Free-Running Model SUBOFF with an Autopilot System

Lin

Chiu

2021

Applied Sciences

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On the basis of a full-appendage DARPA SUBOFF model (DTRC model 5470), a scale (λ = 0.535) semi-autonomous submarine free-running model (SFRM) was designed for testing its manoeuvrability and stability in the constrained water. Prior to the experimental tests of the SFRM, a six-degree-of-freedom (6-DOF) manoeuvre model with an autopilot system was developed by using logic operations in MATLAB. The SFRM’s attitude and its trim polygon were presented by coping with the changes in mass and trimming moment. By adopting a series of manoeuvring tests in empty tanks, the performances of the SFRM were introduced in cases of three sailing speeds. In addition, the PD controller was established by considering the simulation results of these manoeuvring tests. The optimal control gains with respect to each manoeuvring test can be calculated by using the PID tuner in MATLAB. Two sets of control gains derived from the optimal characteristics parameters were compared in order to decide on the most appropriate PD controller with the line-of-sight (LOS) guidance algorithm for the SFRM in the autopilot simulation. Eventually, the simulated trajectories and course angles of the SFRM would be illustrated in the post-processor based on the Cinema 4D modelling.

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Section: Vertical Zigzag Testmentioning

confidence: 96%

Section: Trim Polygonmentioning

confidence: 99%

mentioning

confidence: 99%

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Stability and Manoeuvrability Simulation of a Semi-Autonomous Submarine Free-Running Model SUBOFF with an Autopilot System

Lin

Chiu

2021

Applied Sciences

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“…Typical orientation is in the prone position with the longitudinal axis of the body parallel to the earth-based horizontal plane ( Webb 2006 ). When the fore and aft of a free-floating body are at the same level so that the gravitational and buoyancy forces are balanced, such an orientation is said to be in trim, which maintains longitudinal stability ( Burcher and Rydill 1994 ; Renilson 2015 ). In trim, the longitudinal axis of a body would parallel the horizontal plane.…”

Section: Introductionmentioning

confidence: 99%

“…The up-thrust positioned at the CB counters the downward force due to gravity from the CM. This arrangement generates correcting torques to counter instabilities and provide longitudinal stability against pitching moments (i.e., up and down rotation about a transverse axis), and provide transverse stability to resist rolling moments (i.e., rotation around the longitudinal axis) due to internal or external perturbations ( Renilson 2015 ). The greater the vertical distance between the CM and the CB, the greater the resistance to pitching and rolling.…”

Section: Introductionmentioning

confidence: 99%

Swimming Turned on Its Head: Stability and Maneuverability of the Shrimpfish (Aeoliscus punctulatus)

Fish

Holzman

2019

Integrative Organismal Biology

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Synopsis The typical orientation of a neutrally buoyant fish is with the venter down and the head pointed anteriorly with a horizontally oriented body. However, various advanced teleosts will reorient the body vertically for feeding, concealment, or prehension. The shrimpfish (Aeoliscus punctulatus) maintains a vertical orientation with the head pointed downward. This posture is maintained by use of the beating fins as the position of the center of buoyancy nearly corresponds to the center of mass. The shrimpfish swims with dorsum of the body moving anteriorly. The cross-sections of the body have a fusiform design with a rounded leading edge at the dorsum and tapering trailing edge at the venter. The median fins (dorsal, caudal, anal) are positioned along the venter of the body and are beat or used as a passive rudder to effect movement of the body in concert with active movements of pectoral fins. Burst swimming and turning maneuvers by yawing were recorded at 500 frames/s. The maximum burst speed was 2.3 body lengths/s, but when measured with respect to the body orientation, the maximum speed was 14.1 body depths/s. The maximum turning rate by yawing about the longitudinal axis was 957.5 degrees/s. Such swimming performance is in line with fishes with a typical orientation. Modification of the design of the body and position of the fins allows the shrimpfish to effectively swim in the head-down orientation.

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CFD-Based Boundary Layer Prediction of Axisymmetric Bodies of Revolution

Akolekar¹,

Pook²,

Ranmuthugala³

2020

Australasian Fluid Mechanics Conference (AFMC)

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The design of underwater vehicle propulsors is sensitive to the strength of the adverse pressure gradient (APG) in the stern region. In order to assess this sensitivity, boundary layer properties for different stern shapes derived from the unappended BB2 generic underwater vehicle geometry, an axisymmetric body of revolution, were computed using four different computational fluid dynamics (CFD) Reynolds-Averaged Navier-Stokes (RANS) based turbulence models. It was found that as the stern became steeper (larger APG), there was an increased difference between the boundary layer prediction from the four turbulence models. Initially, boundary layer parameters for the unappended BB2 geometry were validated against experimental measurements from the Defence Science and Technology Group low speed wind tunnel for a Reynolds number of approximately four million with zero angle of incidence. It was found that the Baseline Reynolds stress model (BSL-RSM) closely matched the experimental skin friction and boundary layer profiles at all measurement locations, notably in the stern region, which is a significant improvement from previous studies.

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Introduction

Cited by 6 publications

References 0 publications

Stability and Manoeuvrability Simulation of a Semi-Autonomous Submarine Free-Running Model SUBOFF with an Autopilot System

Stability and Manoeuvrability Simulation of a Semi-Autonomous Submarine Free-Running Model SUBOFF with an Autopilot System

Swimming Turned on Its Head: Stability and Maneuverability of the Shrimpfish (Aeoliscus punctulatus)

CFD-Based Boundary Layer Prediction of Axisymmetric Bodies of Revolution

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