scholarly journals Influence of Spatially Varying Flow on the Dynamic Response of a Waterjet inside an SES

2014 ◽  
Vol 2014 ◽  
pp. 1-18 ◽  
Author(s):  
Michael R. Motley ◽  
Brant R. Savander ◽  
Yin L. Young
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Three Dimensional ◽  
System A ◽  
Air Cushion ◽  
Hydroelastic Response ◽  
Spatially Varying ◽  
Blade Loads ◽  
High Thrust ◽  
Flow Nonuniformity

Surface Effect Ships (SES) are a promising fuel-efficient ship technology that typically carry most of their weight on an air cushion. To accommodate its shallow draft and slender side hulls and to absorb the high thrust and power required for high-speed applications, waterjets are typically used as the primary propulsion system. A waterjet typically has a flush mounted inlet and operates under complex three-dimensional flow conditions that result in highly nonuniform flows. The objectives of this work are to quantify the flow nonuniformity and the influence of unsteady cavitation on the response of an SES-waterjet system and to investigate the effect of flow nonuniformity and cavitation on the dynamic hydroelastic response of the rotor and stator blades. The results showed that as the flow advances through the pump, the ingested boundary layer from the bottom of the side hulls becomes increasingly nonuniform, particularly between the rotor and stator. The flow nonuniformity was shown to result in hydrodynamic load fluctuations and high side forces on the rotor and stator blades. The unbalanced blade loads lead to the generation of net upward forces on the pump casing and shaft. Flow nonuniformity also leads to unsteady cavitation and unsteady blade stresses and deformations.

Quantification of Facial Motion for Objective Evaluation Using a High-Speed Three-Dimensional Face Measurement System-A Pilot Study

2006 ◽  
Vol 27 (7) ◽  
pp. 1023-1029 ◽  
Author(s):  
Seiichi Nakata ◽  
Yukio Sato ◽  
Pujitha Gunaratne ◽  
Yoshiro Suzuki ◽  
Saiko Sugiura ◽  
...  
Keyword(s):  
Pilot Study ◽  
Measurement System ◽  
High Speed ◽  
Three Dimensional ◽  
Objective Evaluation ◽  
Facial Motion ◽  
System A ◽  
Dimensional Face

Jets, Props and Air Cushions: Propulsion Technology and Surface Effect Ships

1968 ◽  
Author(s):  
Alfred Skolnick ◽  
Z. G. Wachnik
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Broad Scope ◽  
The Status ◽  
Air Cushion

Following a brief review of the background and formulation of the jointly sponsored Navy/Commerce Department’s Surface Effect Ships (SES) Program, the paper offers a broad scope presentation on propulsion for SES, e.g., waterjets, supercavitating propellers, and lift fans. The problems associated with establishing the feasibility of successful designs and construction of such ships are considered, the status of development assessed and the efforts still remaining accordingly” defined. The paper deals primarily with the propulsion considerations of high speed ships using the air cushion principle in combination with vestigial rigid sidewall design.

Cobblestone Oscillations of an SES with Flexible Bag Aft Seal

1995 ◽  
Vol 39 (01) ◽  
pp. 25-41
Author(s):  
Sverre Steen ◽  
Odd M. Faltinsen
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Surface Effect ◽  
Frequency Range ◽  
Resonance Frequencies ◽  
Leakage Area ◽  
Air Cushion ◽  
Vertical Accelerations ◽  
Spatially Varying ◽  
The Mathematical Model

The high-frequency dynamic response of surface effect ships (SES) equipped with a flexible bag aft seal is studied. The results show dominating vertical accelerations in a frequency range important for passenger comfort and crew work ability. The mathematical model for the craft dynamic response accounts for the motions and accelerations in heave and pitch induced by both the unsteady uniform pressure and the spatially varying air cushion pressure. The effect of a flexible bag aft seal and a variable leakage area under the seals is included. The bag dynamic response is treated as linear and quasistatic. It is shown how the flexible bag reduces the spatial pressure resonance frequencies of a 35 m SES. The variable leakage area under the bag is found important for the response of the craft in low sea states.

Full-scale Performance of the SES Motion Control System

2015 ◽  
Author(s):  
Øyvind F. Auestad ◽  
J. William McFann ◽  
Jan T. Gravdahl
Keyword(s):  
Control System ◽  
Motion Control ◽  
High Speed ◽  
Wind Farm ◽  
Surface Effect ◽  
Vertical Plane ◽  
Full Scale ◽  
Offshore Wind ◽  
Motion Control System ◽  
Air Cushion

The pressurized air cushion on a Surface Effect Ship (SES) can lift up to 80% of total vessel mass. The SES Motion Control System (SES-MCS) controls the vent valves which again controls the air cushion pressure, assuming lift fan air flow is pressurizing the air cushion. By controlling the air cushion pressure one can significantly counteract vertical sea wave disturbances, ensure high passenger comfort and reduce sea-sickness. The case studied in this work is the Umoe Mandal Wave Craft prototype, ’Umoe Ventus’, which is a high-speed offshore wind-farm service vessel specially designed for control in the vertical plane. The SES-MCS can adjust the draft from 1m to 3.2m in less time than the wave period. The SES-MCS can reduce motions significantly in order to perform Operation and Maintenance (O&M) in high seas. The craft is the fastest wind-farm service vessel of its size with high comfort in all relevant sea states. The performance of the SES-MCS is demonstrated through full-scale sea trials.

Multihull and Surface-Effect Ship Configuration Design: A Framework for Powering Minimization

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Ronald W. Yeung ◽  
Hui Wan
Keyword(s):  
High Speed ◽  
Surface Effect ◽  
Early Stage ◽  
Base Line ◽  
Total Displacement ◽  
Surface Effect Ship ◽  
Linearized Theory ◽  
Air Cushion ◽  
New Formula ◽  
Analytical Expressions

The powering issue of a high-speed marine vehicle with multihulls and air-cushion support is addressed, since there is an often need to quickly evaluate the effects of several configuration parameters in the early stage of the design. For component hulls with given geometry, the parameters considered include the relative locations of individual hulls and the relative volumetric ratios. Within the realm of linearized theory, an interference-resistance expression for hull-to-hull interaction is first reviewed, and then a new formula for hull-and-pressure distribution interference is derived. Each of these analytical expressions is expressed in terms of the Fourier signatures or Kochin functions of the interacting component hulls, with the separation, stagger, and speed as explicit parameters. Based on this framework, an example is given for assessing the powering performance of a catamaran (dihull) as opposed to a tetrahull system. Also examined is the wave resistance of a surface-effect ship of varying cushion support in comparison with that of a base line catamaran, subject to the constraint of constant total displacement.

High-speed brightfield 3-D imaging and 3-D image analysis of thick and overlapped cell clusters in cytological preparations

1994 ◽  
Vol 52 ◽  
pp. 218-219
Author(s):  
Robert W. Mackin
Keyword(s):  
Image Analysis ◽  
High Speed ◽  
Three Dimensional ◽  
Image Data ◽  
Ccd Camera ◽  
Objective Lens ◽  
Array Processor ◽  
Vaginal Smears ◽  
Low Contrast ◽  
Computer Controlled

This paper presents two advances towards the automated three-dimensional (3-D) analysis of thick and heavily-overlapped regions in cytological preparations such as cervical/vaginal smears. First, a high speed 3-D brightfield microscope has been developed, allowing the acquisition of image data at speeds approaching 30 optical slices per second. Second, algorithms have been developed to detect and segment nuclei in spite of the extremely high image variability and low contrast typical of such regions. The analysis of such regions is inherently a 3-D problem that cannot be solved reliably with conventional 2-D imaging and image analysis methods.High-Speed 3-D imaging of the specimen is accomplished by moving the specimen axially relative to the objective lens of a standard microscope (Zeiss) at a speed of 30 steps per second, where the stepsize is adjustable from 0.2 - 5μm. The specimen is mounted on a computer-controlled, piezoelectric microstage (Burleigh PZS-100, 68/μm displacement). At each step, an optical slice is acquired using a CCD camera (SONY XC-11/71 IP, Dalsa CA-D1-0256, and CA-D2-0512 have been used) connected to a 4-node array processor system based on the Intel i860 chip.

Effects of Three-Dimensional Pressure Gradients on High-Speed Turbulent Boundary Layers

2021 ◽  
Author(s):  
Scott J. Peltier ◽  
Brian E. Rice ◽  
Ethan Johnson ◽  
Venkateswaran Narayanaswamy ◽  
Marvin E. Sellers
Keyword(s):  
Boundary Layers ◽  
High Speed ◽  
Three Dimensional ◽  
Turbulent Boundary Layers ◽  
Pressure Gradients
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