Hydrodynamic Test Facilities in Naval Systems Research Center- Large Towing Tank, High Speed Towing Tank and Flow Noise Simulator

2021 ◽  
Vol 56 (6) ◽  
pp. 867-871
Author(s):  
Takayuki Mori
Keyword(s):  
High Speed ◽  
Research Center ◽  
Towing Tank ◽  
Flow Noise ◽  
Systems Research

Observation and Scaling of Tip Vortex Cavitation on Elliptical Hydrofoils

2011 ◽  
Author(s):  
Shigeki Nagaya ◽  
Risa Kimoto ◽  
Kenji Naganuma ◽  
Takayuki Mori
Keyword(s):  
Water Quality ◽  
Reynolds Number ◽  
High Speed ◽  
Tip Vortex ◽  
Video Observation ◽  
Tip Vortex Cavitation ◽  
Air Content ◽  
Sheet Cavitation ◽  
High Speed Video ◽  
Systems Research

Experimental study on tip vortex cavitation (TVC) was carried out for elliptical hydrofoils with various chord lengths. The purpose of the experiment was to clarify the influences of Reynolds number and water quality on tip vortex cavitation. Experiments were made in a large cavitation tunnel of the Naval Systems Research Center, TRDI/Ministry of Defense Japan. The elliptical hydrofoils tested were NACA 0012 cross section with chord lengths of 500mm, 250mm and 50mm. Reynolds number based on hydrofoil chord length was 2×105 < ReC < 7.4×106. Water quality of the tunnel was characterized by air content and nuclei distribution. Air content of the tunnel was varied between 30% and 80%. Nuclei distribution was measured by a cavitation susceptibility meter (CSM) with center-body venturi. Cavitation inception was determined from high speed video observation. A standard formula, (σL/σS) = (ReL/ReS)n, was applied for the scaling. In the present study, exponent of the scaling law n was found to be 0.2 < n < 0.4. High speed video observation showed that the process of the TVC inception strongly depends on water quality. In the experiments, unsteady behaviors of TVC were also investigated. Strong interactions between sheet cavitation and TVC were observed.

SLAM CHARACTERISTICS OF A HIGH-SPEED WAVE PIERCING CATAMARAN IN IRREGULAR WAVES

2021 ◽  
Vol 156 (A1) ◽  
Author(s):  
B J French ◽  
G A Thomas ◽  
M R Davis
Keyword(s):  
Vertical Velocity ◽  
Significant Wave Height ◽  
High Speed ◽  
Irregular Waves ◽  
Two Dimensional ◽  
Towing Tank ◽  
Filling Height ◽  
Load Distributions ◽  
Poor Indicator ◽  
Wave Elevations

Slam characteristics of a 112m INCAT wave piercing catamaran in a range of realistic irregular sea conditions are presented in this paper. Towing tank testing of a 2.5 m hydroelastic segmented catamaran model was used to gather a database of slam events in irregular seas. The model was instrumented to measure motions, centrebow surface pressures and forces, encountered wave elevations and wave elevations within the bow area tunnel arches. From these measurements characteristics of the vessel slamming behaviour are examined: in particular relative vertical velocity, centrebow immersion, archway wave elevations and slam load distributions. A total of 2,098 slam events were identified over 22 different conditions, each containing about 80 to 100 slam events. The data, although inherently scattered, shows that encounter wave frequency and significant wave height are important parameters with regard to centrebow slamming. Relative vertical velocity was found to be a poor indicator of slam magnitude and slams were found to occur before the centrebow arch tunnel was completely filled, supporting the application of a two-dimensional filling height parameter as a slam indicator.

Dynamic Instability of a High-Speed Planing Boat Model

2000 ◽  
Vol 37 (03) ◽  
pp. 146-152
Author(s):  
Eric Thornhill ◽  
Brian Veitch ◽  
Neil Bose
Keyword(s):  
Dynamic Stability ◽  
High Speed ◽  
Research Council ◽  
Dynamic Instability ◽  
National Research Council ◽  
Scale Model ◽  
Clear Water ◽  
Towing Tank ◽  
Stability Limits ◽  
Resistance Tests

A series of bare-hull resistance and self-propulsion tests were carried out on a 1/8 scale model of a 11.8 m long, waterjet-propelled planing hull in the clear water towing tank at the National Research Council of Canada's Institute for Marine Dynamics. The bare-hull resistance tests, performed with the waterjet inlets closed, spanned a range of eight model velocities and nine ballast conditions consisting of three displacements each with three positions of the longitudinal center of gravity. The hull was then fitted with two model waterjet thrusters and tested over the same speeds and ballast conditions. Dynamic instability, or porpoising, was seen during certain high-speed tests. A discussion of this behavior and its relation to published dynamic stability limits is given.

Investigation of Environmental Effects of High Speed Boats

2020 ◽  
Author(s):  
Ahmet Dursun Alkan ◽  
Onur Usta ◽  
Alpay Acar ◽  
Elis Atasayan
Keyword(s):  
High Speed ◽  
Navier Stokes ◽  
Noise Prediction ◽  
Total Resistance ◽  
Test Results ◽  
Negative Effects ◽  
Towing Tank ◽  
Towing Tank Test ◽  
Tank Test ◽  
Propulsion Power

Luxury high-speed boats are increasingly being used for entertainment purposes. However, not only humans, but also animals are negatively affected by high-speed boats, and time is running out fast for people to do something about it. This study presents a review of current negative effects of high-speed boats to the environment. In this study, the flow around a benchmark planing Fridsma boat is simulated by CFD and resistance values for different non-dimensional Froude number (Fn) conditions are validated from the experimental results obtained from the literature. Using the same CFD methodology, a catamaran model in which the towing tank test results are available, is simulated for different Fn conditions and resistance values are predicted. In the CFD analysis, unsteady flow around the Fridsma hull model and catamaran model is simulated using overset meshing technique and turbulence is modeled by Reynolds Averaged Navier Stokes (RANS) with SST (Menter) k-omega turbulence model. Resistance values are compared with the experimental data and required propulsion powers are estimated for different Fn conditions. Then, total resistance of the catamaran for full-scale vessel is calculated using an extrapolation method and required propulsion power predictions are conducted. Noise prediction, corresponding to the required propulsion power are presented. In particular, the change of noise level and harmful gases released into the environment, when the speed of the vessel increases are examined and discussed. Consequently, it is believed that this study would lay an important foundation for the widespread investigation for the negative effects of the high-speed boats in the future.

scholarly journals Experimental towing tank tests on high speed displacement ship

2020 ◽  
Vol 916 ◽  
pp. 012080
Author(s):  
F Pacuraru ◽  
A Presura ◽  
S Pacuraru
Keyword(s):  
High Speed ◽  
Towing Tank

The Pransky interview: Dr Steve Cousins, CEO, Savioke, Entrepreneur and Innovator

2016 ◽  
Vol 43 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Joanne Pransky
Keyword(s):  
Computer Science ◽  
Open Source ◽  
Industrial Robot ◽  
Chief Executive ◽  
Research Center ◽  
Information Technology Industry ◽  
Content Type ◽  
Track Record ◽  
Systems Research ◽  
A Company

Purpose – The following paper is a “Q & A interview” conducted by Joanne Pransky of Industrial Robot Journal as a method to impart the combined technological, business and personal experience of a prominent, robotic industry engineer-turned successful business leader, regarding the commercialization and challenges of bringing technological inventions to market while overseeing a company. The paper aims to discuss these issues. Design/methodology/approach – The interviewee is Dr Steve Cousins, a seasoned executive, entrepreneur and innovator with a strong track record for managing research and development organizations and realizing a significant return on investment. Dr Cousins has dedicated the past near-decade of his life to the mission of building and deploying personal and service robotic technology to assist people. In this interview, Dr Cousins discusses some of the technical and business insights that have led to his most recent robotic advancements as Chief Executive Officer (CEO) of Savioke, a company that is creating autonomous robot helpers for the services industry. Findings – Dr Cousins received his BS and MS degrees in computer science from Washington University, and holds a PhD in computer science from Stanford University. Dr Cousins managed the Advanced Systems Development Laboratory at the Xerox Palo Alto Research Center (PARC) and then went on to lead the IBM Almaden Research Center, one of the top human–computer interaction research groups in the world, as the Senior Manager of the User-Focused Systems Research Group. While at IBM, Dr Cousins earned a micro-MBA. Originality/value – Dr Cousins is spearheading a new business model for robotics, Robots as a Service (RaaS), with Savioke’s flagship mobile robot, Relay. Based on the information technology industry service trend of improving customer experiences, Savioke is successfully applying RaaS to the hospitality industry with about 10 Relays at half a dozen US major hotels. Before founding Savioke, Dr Cousins was the President and CEO of Willow Garage, where he oversaw the creation of the robot operating system (ROS), the PR2 robot and the open-source TurtleBot. In the last three years of his tenure at Willow Garage, Dr Cousins spun off eight successful companies: Suitable Technologies (maker of the Beam remote presence system); Industrial Perception, Inc. (acquired by Google in 2013); Redwood Robotics (acquired by Google in 2013); HiDOF (ROS and robotics consulting); Unbounded Robotics; The Open Source Robotics Foundation; The OpenCV Foundation; and The Open Perception Foundation. Dr Cousins is an active participant in the Robots for Humanity project.

scholarly journals Advances in Thin Film Sensor Technologies for Engine Applications

1997 ◽  
Author(s):  
Jih-Fen Lei ◽  
Lisa C. Martin ◽  
Herbert A. Will
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
High Speed ◽  
Ceramic Matrix Composites ◽  
Surface Strain ◽  
Research Center ◽  
Strain Gauges ◽  
Nasa Lewis Research ◽  
Film Sensor ◽  
Thin Film Sensor

Advanced thin film sensor techniques that can provide accurate surface strain and temperature measurements are being developed at NASA Lewis Research Center. These sensors are needed to provide minimally intrusive characterization of advanced materials (such as ceramics and composites) and structures (such as components for Space Shuttle Main Engine, High Speed Civil Transport, Advanced Subsonic Transports and General Aviation Aircraft) in hostile, high-temperature environments, and for validation of design codes. This paper presents two advanced thin film sensor technologies: strain gauges and thermocouples. These sensors are sputter deposited directly onto the test articles and are only a few micrometers thick; the surface of the test article is not structurally altered and there is minimal disturbance of the gas flow over the surface. The strain gauges are palladium-13% chromium based and the thermocouples are platinum-13% rhodium vs. platinum. The fabrication techniques of these thin film sensors in a class 1000 cleanroom at the NASA Lewis Research Center are described. Their demonstration on a variety of engine materials, including superalloys, ceramics and advanced ceramic matrix composites, in several hostile, high-temperature test environments are discussed.

scholarly journals Powering Out of Trouble

2013 ◽  
Vol 135 (12) ◽  
pp. 36-41 ◽  
Author(s):  
Lee S. Langston
Keyword(s):  
Power Plant ◽  
High Speed ◽  
Combined Cycle ◽  
Research Center ◽  
Side View ◽  
Noise And Vibration ◽  
Low Speed ◽  
Supersonic Inlet ◽  
The World ◽  
Ejector Nozzle

This article presents a study of Pratt & Whitney’s J58, till date the best and high-powered engine for manufacturing lessons required for the development of F35 Joint Strike Fighter. The J58 Blackbird engine is a variable cycle engine, a turbojet/ramjet combined-cycle engine. It is a conventional afterburning turbojet for take-off and transonic flight, and it approximates a ramjet during high-speed supersonic cruise. The power plant for the Blackbirds is a marvelous development on the part of Pratt & Whitney, as it is the only engine of its kind in the world. The noise and vibration from a J58 test was so great that it could rattle the side-view mirror off nearby cars. The engine was developed at an isolated research center in Florida. At take-off and low-speed flight, the J58 engine/afterburner provides most of the thrust. Both of the Blackbird’s twin nacelles contain an engine supersonic inlet, the J58 engine with its afterburner, and an exhaust ejector nozzle. All three components contribute to the Blackbird’s propulsive thrust in varying proportions, depending on flight speed.

Hydrodynamics of High-Speed Planing Craft: Savitsky Method and 2D+t Approach

2021 ◽  
Author(s):  
M. Javad Javaherian ◽  
Richard Royce ◽  
Raju Datla ◽  
Christine M. Gilbert
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Hydrodynamic Force ◽  
Prediction Method ◽  
Water Entry ◽  
Planing Craft ◽  
Towing Tank ◽  
Entry Model ◽  
Calm Water

The progressive interest in high-speed planing craft has made it crucial to conduct more accurate assessments of the behavior of these vessels in motion. In this paper, a 2D+t approach is employed to predict the resistance, trim and wetted length of a prismatic planing craft cruising in calm water. Although this approach is based on original Zarnick 2D+t model, the hydrodynamic force is estimated using experimental wedge drop experiments in conjunction with the Logvinovich wedge water entry model. The analysis is repeated employing Savitsky prediction method and results are compared with that of towing tank measurements of Naples series. The comparison shows that the Savitsky prediction results match very well with the experimental data. The 2D+t approach also shows reasonable outcomes for the trim and wetted length. However, this approach slightly underestimates the resistance of the craft at very low Froude numbers.

CFD Analysis of the Combustion of Hydrogen in a Simulated Two Dimensional Scramjet Engine

2004 ◽  
Author(s):  
J. K. Rencher ◽  
A. H. Massoudi ◽  
D. W. Guillaume
Keyword(s):  
High Speed ◽  
Premixed Combustion ◽  
Research Center ◽  
Test Facility ◽  
Published Data ◽  
Two Dimensional ◽  
Hydrogen Fuel ◽  
Engine Model ◽  
Scramjet Engine ◽  
Langley Research Center

The purpose of this research is to accurately simulate combustion in a scramjet engine using a CFD (Computational Fluid Dynamics) software package called Fluent and to validate the results with existing experimental data from NASA Langley Research Center[1]. The use of a particular engine characteristic called compression ramp injection was used to increase the mixing of air and fuel inside the combustion duct as well as provide the necessary compression of the fuel/air mixture. The duct length and other pertinent dimensions were also determined by published data from NASA [1]. The engine model used is relatively small and, at this stage, can be thought of as a two dimensional combustor duct rather than a true engine. The scope of this project involves the simultaneous calculations and analysis of both combustion and high-speed compressible flow. Thermodynamic data was used to create hydrogen fuel in a Fluent module called prePDF (probability density function), which calculates the look-up tables and chemical reactions for the fuel. Non-premixed combustion at Mach 2 was carried out using various equivalence ratios, (ratio of actual fuel/air mixture to stoichiometric fuel/air mixture) ranging from .4 to 1.4. The basic characteristics of the numerical model are as follows: steady state; non-premixed combustion; hydrogen fuel PDF model with 4 species; k-epsilon viscous model. Results of the numerical analysis include a comparison of combustion efficiencies for various equivalence ratios to the combustion efficiencies and equivalence ratios obtained by NASA in their experimental ground test facility at Langley Research Center [1].

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