Conceptual Design of the Flow Noise Simulator

2003 ◽  
Author(s):  
Ryuichi Sato ◽  
Takayuki Mori ◽  
Ryo Yakushiji ◽  
Kenji Naganuma ◽  
Masaharu Nishimura ◽  
...  
Keyword(s):  
Conceptual Design ◽  
Large Scale ◽  
Scale Model ◽  
Variable Pressure ◽  
Cavitation Noise ◽  
Flow Noise ◽  
Model Studies ◽  
Surface Ship ◽  
Noise Measurements ◽  
Under Construction

The Flow Noise Simulator (FNS) of the 1st Research Center of TRDI/JDA (Japan Defense Agency) is a large, variable pressure, recirculating water tunnel with very low background noise level. The tunnel is 20m high and 49m long, containing 2000m3 of water. The test section has a square cross section of 2m × 2m with 10m in length. It will accept large size surface ship models of 6m, submarine models of 4m in length and full scale ship appendix models. The FNS is currently under construction and will be accomplished in 2005. It will be used for a wide variety of hydrodynamic and hydroacoustic testing of surface ships and submarines, such as propeller cavitation noise measurements and propeller-hull interaction observation, with sufficiently large scale models. Conceptual design of the FNS was started in 1996 and evaluated by following scale model studies. This paper discusses some technical issues of the FNS.

Hydrodynamic Design of the Flow Noise Simulator

2003 ◽  
Author(s):  
Takayuki Mori ◽  
Yoshinao Komatsu ◽  
Hirobumi Kaneko ◽  
Ryuichi Sato ◽  
Hajime Izumi ◽  
...  
Keyword(s):  
Background Noise ◽  
Scale Model ◽  
Variable Pressure ◽  
Intensity Level ◽  
Flow Uniformity ◽  
Flow Noise ◽  
Model Studies ◽  
Circuit Component ◽  
Circuit Components ◽  
Careful Design

The Flow Noise Simulator (FNS) of the 1st Research Center of TRDI/JDA (Japan Defense Agency) is a large, variable pressure, recirculating water tunnel with very low background noise level. (Figure 1) The hydrodynamic goals of the FNS include an excellent flow uniformity of 1% deviation, low turbulence intensity level of 0.5% and it requires careful design of circuit components, for example, contraction, diffusers, bends and turning vanes. In the conceptual design of the FNS, a series of detailed CFD analysis and component model experiment has been conducted to determine the geometry of the circuit component. Further, the entire circuit performances have been evaluated by following scale model studies. This paper discusses some hydrodynamic design considerations for the FNS.

scholarly journals LARGE SCALE MODEL TESTS OF PLACED STONE BREAKWATERS

1976 ◽  
Vol 1 (15) ◽  
pp. 147 ◽  
Author(s):  
Charles K. Sollitt ◽  
Donald H. Debok
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Small Scale ◽  
Stable Model ◽  
Model Studies ◽  
Drag Forces ◽  
Port Facilities ◽  
Large Scale Model ◽  
Wave Heights ◽  
Water Depths

Large scale model studies reveal that Reynolds scaling can affect the apparent stability and wave modifying properties of layered breakwater structures. Results of a study for a breakwater configuration designed to protect offshore power and port facilities in water depths to 60 feet are presented and discussed. The armor layer of this structure is formed from quarried rock of irregular rectangular parallelepiped shape, individually placed perpendicular to 1:2 seaward slope and crest. The resulting armor layer is relatively smooth, densely packed and very stable. Model studies of similar configurations were studied at 1:10, 1:20 and 1:100 scale ratios. Stability, runup, rundown and reflection were measured for a variety of water depths, wave heights and periods. Analysis of the large scale test results establish that the placed stone armor is approximately as stable as dolos armor units. Runup, rundown and reflection respond similar to rough, impermeable slopes. Comparison of large and small scale results demonstrate that relative increases in drag forces at lower Reynolds numbers decrease stability and runup in small scale models.

scholarly journals Cloud condensation nuclei production associated with atmospheric nucleation: a synthesis based on existing literature and new results

2012 ◽  
Vol 12 (24) ◽  
pp. 12037-12059 ◽  
Author(s):  
V.-M. Kerminen ◽  
M. Paramonov ◽  
T. Anttila ◽  
I. Riipinen ◽  
C. Fountoukis ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Large Scale ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Scientific Information ◽  
Scale Model ◽  
Condensation Nuclei ◽  
Uncertainty Range ◽  
Model Studies ◽  
Atmospheric Nucleation

Abstract. This paper synthesizes the available scientific information connecting atmospheric nucleation with subsequent cloud condensation nuclei (CCN) formation. We review both observations and model studies related to this topic, and discuss the potential climatic implications. We conclude that CCN production associated with atmospheric nucleation is both frequent and widespread phenomenon in many types of continental boundary layers, and probably also over a large fraction of the free troposphere. The contribution of nucleation to the global CCN budget spans a relatively large uncertainty range, which, together with our poor understanding of aerosol-cloud interactions, results in major uncertainties in the radiative forcing by atmospheric aerosols. In order to better quantify the role of atmospheric nucleation in CCN formation and Earth System behavior, more information is needed on (i) the factors controlling atmospheric CCN production and (ii) the properties of both primary and secondary CCN and their interconnections. In future investigations, more emphasis should be put on combining field measurements with regional and large-scale model studies.

Experiments in Urban Modelling for County Structure Planning: The Area 8 Pilot Model

1974 ◽  
Vol 6 (4) ◽  
pp. 455-478 ◽  
Author(s):  
M Batty ◽  
R Bourke ◽  
P Cormode ◽  
M Anderson-Nicholls
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Calibration Technique ◽  
Direct Search Methods ◽  
Pilot Model ◽  
Large Scale Model ◽  
Urban Modelling ◽  
Speed Up ◽  
Newton Raphson ◽  
Under Construction

This paper presents the form of the pilot model designed for the Reading–Wokingham–Aldershot–Basingstoke Subregional Study, known as Area 8. The model is based on the well-developed structure first used by Lowry, but in the quest to make the model operational, significant improvements have been made to the use of locational constraints, the treatment of external zones, and calibration. The original model is first outlined, and then a number of algorithms designed to speed up the application of the constraints are tested, the best one reducing the overall model running time by 60%. External zones are considered in the context of constraints, and a much accelerated calibration technique based on a combination of Newton–Raphson and direct-search methods is introduced. The calibration of the model in Area 8 is described, and the problem of measuring and interpreting locational attraction is also addressed. Finally the implications of using the model in county structure planning are traced, in preparation for the application of the large-scale model which is under construction.

Uncertainty analysis at large scales: limitations and subjectivity of current practices - a water quality case study

2007 ◽  
Vol 56 (6) ◽  
pp. 1-9 ◽  
Author(s):  
R.M. Bijlsma ◽  
P. Groenendijk ◽  
M.W. Blind ◽  
A.Y. Hoekstra
Keyword(s):  
Uncertainty Analysis ◽  
Large Scale ◽  
Evidence Base ◽  
Uncertainty Assessment ◽  
Scale Model ◽  
Small Scale ◽  
Model Studies ◽  
Large Scale Model ◽  
Current Practices

Uncertainty analysis for large-scale model studies is a challenging activity that requires a different approach to uncertainty analysis at a smaller scale. However, in river basin studies, the practice of uncertainty analysis at a large scale is mostly derived from practice at a small scale. The limitations and inherent subjectivity of some current practices and assumptions are identified, based on the results of a quantitative uncertainty analysis exploring the effects of input data and parameter uncertainty on surface water nutrient concentration. We show that: (i) although the results from small- scale sensitivity analysis are often applied at larger scales, this is not always valid; (ii) the current restriction of the uncertainty assessment to uncertainty types with a strong evidence base gives structurally conservative estimates; (iii) uncertainty due to bias is usually not assessed, but it may easily outweigh the effects of variability; (iv) the uncertainty bandwidth may increase for higher aggregation levels, although the opposite is the standard assumption.

Large scale model studies of vertical recording

1981 ◽  
Vol 17 (6) ◽  
pp. 2541-2543 ◽  
Author(s):  
J. Monson ◽  
R. Fung ◽  
A. Hoagland
Keyword(s):  
Large Scale ◽  
Scale Model ◽  
Model Studies ◽  
Large Scale Model

TVC Noise Envelope—An Approach to Tip Vortex Cavitation Noise Scaling

1982 ◽  
Vol 26 (01) ◽  
pp. 65-75
Author(s):  
Robert Latorre
Keyword(s):  
Tip Vortex ◽  
Scale Model ◽  
Cavitation Noise ◽  
Scaling Method ◽  
Tip Vortex Cavitation ◽  
Noise Measurements ◽  
Cavitation Nuclei ◽  
Simulation Results ◽  
Large Model ◽  
Good Agreement

Noise measurements of the tip vortex cavitation generated by a large model hydrofoil and its one-quarter scale model are presented to discuss the features of tip vortex cavitation (TVC) noise and noise scaling. The concept of the TVC noise envelope is introduced to divide the cavitation noise into incipient and fully developed TVC noise. The cavitation noise scaling method of Bojorheden and Astrom is compared with the method of Levkovskii for scaling the fully developed TVC noise. A theoretical model of the cavitation nuclei spiraling around an idealized Rankine vortex is introduced to model the characteristic bursts in the incipient TVC noise and predict the inception of TVC noise. The simulation results for the large and small foils are shown to be in good agreement with the experimental noise measurements.

scholarly journals Cloud condensation nuclei production associated with atmospheric nucleation: a synthesis based on existing literature and new results

2012 ◽  
Vol 12 (8) ◽  
pp. 22139-22198
Author(s):  
V.-M. Kerminen ◽  
M. Paramonov ◽  
T. Anttila ◽  
I. Riipinen ◽  
C. Fountoukis ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Large Scale ◽  
Cloud Condensation Nuclei ◽  
Large Fraction ◽  
Scientific Information ◽  
Scale Model ◽  
Condensation Nuclei ◽  
Uncertainty Range ◽  
Model Studies ◽  
Atmospheric Nucleation

Abstract. This paper synthesizes the available scientific information connecting atmospheric nucleation with subsequent Cloud Condensation Nuclei (CCN) formation. We review both observations and model studies related to this topic, and discuss the potential climatic implications. We conclude that CCN production associated with atmospheric nucleation is both frequent and widespread phenomenon in many types of continental boundary layers, and probably also over a large fraction of the free troposphere. The contribution of nucleation to the global CCN budget spans a relatively large uncertainty range, which, together with our poor understanding of aerosol–cloud interactions, results in major uncertainties in the radiative forcing by atmospheric aerosols. In order to better quantify the role of atmospheric nucleation in CCN formation and Earth System behavior, more information is needed on (i) the factors controlling atmospheric CCN production and (ii) the properties of both primary and secondary CCN and their interconnections. In future investigations, more emphasis should be put on combining field measurements with regional and large-scale model studies.

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