Estimating Propeller Characteristics Using CFD - Estimating Full Scale Propeller Performance

2021 ◽  
Vol 56 (6) ◽  
pp. 908-911
Author(s):  
Takafumi Kawamura
Keyword(s):  
Full Scale ◽  
Propeller Performance

A study on the efficient numerical analysis for the prediction of full-scale propeller performance using CFD

2021 ◽  
Vol 240 ◽  
pp. 109931
Author(s):  
Kwan-Woo Kim ◽  
Kwang-Jun Paik ◽  
Ju-Han Lee ◽  
Soon-Seok Song ◽  
Mehmet Atlar ◽  
...  
Keyword(s):  
Numerical Analysis ◽  
Full Scale ◽  
Propeller Performance

An Investigation Into the Effect of Biofouling on Full-Scale Propeller Performance Using CFD

2019 ◽  
Author(s):  
Soonseok Song ◽  
Yigit Kemal Demirel ◽  
Mehmet Atlar
Keyword(s):  
Open Water ◽  
Full Scale ◽  
Roughness Effect ◽  
Thrust Coefficient ◽  
Propulsion Performance ◽  
Negative Effect ◽  
Precise Prediction ◽  
Torque Coefficient ◽  
Open Water Performance ◽  
Propeller Performance

Abstract The negative effect of biofouling on ship resistance has been investigated since the early days of naval architecture. However, for more precise prediction of fuel consumption of ships, understanding the effect of biofouling on ship propulsion performance is also important. In this study, CFD simulations for the full-scale performance of KP505 propeller in open water, including the presence of marine biofouling, were conducted. To predict the effect of barnacle fouling on the propeller performance, experimentally obtained roughness functions of barnacle fouling were employed in the wall-function of the CFD software. The roughness effect of barnacles of varying sizes and coverages on the propeller open water performance was predicted for advance coefficients ranging from 0.2 to 0.8. From the simulations, drastic effects of barnacle fouling on the propeller open water performance were found. The result suggests that the thrust coefficient decreases while the torque coefficient increases with increasing level of surface fouling, which leads to a reduction of the open water efficiency of the propeller. Further investigations into the roughness effect on the pressure and velocity field, surface pressure and wall shear stress, and propeller vortices were examined.

scholarly journals Cavitation on Model- and Full-Scale Marine Propellers: Steady And Transient Viscous Flow Simulations At Different Reynolds Numbers

2020 ◽  
Vol 8 (2) ◽  
pp. 141 ◽  
Author(s):  
Ville Viitanen ◽  
Timo Siikonen ◽  
Antonio Sánchez-Caja
Keyword(s):  
Reynolds Number ◽  
Numerical Simulations ◽  
Full Scale ◽  
Tip Vortex ◽  
Wake Flow ◽  
Time Step ◽  
Two Phase ◽  
Marine Propellers ◽  
Model Scale ◽  
Propeller Performance

In this paper, we conducted numerical simulations to investigate single and two-phase flows around marine propellers in open-water conditions at different Reynolds number regimes. The simulations were carried out using a homogeneous compressible two-phase flow model with RANS and hybrid RANS/LES turbulence modeling approaches. Transition was accounted for in the model-scale simulations by employing an LCTM transition model. In model scale, also an anisotropic RANS model was utilized. We investigated two types of marine propellers: a conventional and a tip-loaded one. We compared the results of the simulations to experimental results in terms of global propeller performance and cavitation observations. The propeller cavitation, near-blade flow phenomena, and propeller wake flow characteristics were investigated in model- and full-scale conditions. A grid and time step sensitivity studies were carried out with respect to the propeller performance and cavitation characteristics. The model-scale propeller performance and the cavitation patterns were captured well with the numerical simulations, with little difference between the utilized turbulence models. The global propeller performance and the cavitation patterns were similar between the model- and full-scale simulations. A tendency of increased cavitation extent was observed as the Reynolds number increases. At the same time, greater dissipation of the cavitating tip vortex was noted in the full-scale conditions.

Hydrodynamic Performance and Cavitation of an Open Propeller in a Simulated Ice-Blocked Flow

1994 ◽  
Vol 116 (3) ◽  
pp. 185-189 ◽  
Author(s):  
D. Walker ◽  
N. Bose ◽  
H. Yamaguchi
Keyword(s):  
Uniform Flow ◽  
Full Scale ◽  
Hydrodynamic Performance ◽  
Mean Values ◽  
Cavitation Tunnel ◽  
Propeller Performance ◽  
Thrust And Torque

Experiments were done on a 200-mm-dia open propeller behind a simulated ice blockage in a cavitation tunnel. The propeller performance in uniform flow and blocked flow is contrasted over a range of advance coefficients and at different cavitation numbers. Mean thrust and torque coefficients are presented. The types of cavitation, and its intermittent nature over a cycle of operation, are reported. The experiments indicate the likelihood of cavitation at full scale for blocked conditions and illustrate the effects of cavitation on mean values of thrust and torque.

scholarly journals FULL SCALE PREDICTION OF HYDRODYNAMIC NOISE USING COMPUTATIONAL FLUID DYNAMICS

2019 ◽  
Author(s):  
E M Fay
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Marine Mammals ◽  
Bright Light ◽  
Open Water ◽  
Full Scale ◽  
Noise And Vibration ◽  
Vibration Data ◽  
Hydrodynamic Noise ◽  
Propeller Performance

The issues of noise and vibration related to the propulsion system of vessels shines a bright light over the present day operation of sea going vessels. Some of the principal issues coming to the front are not new and are concerned with passenger and crew comfort which has been a touchstone for a decade or more. The most recent, more ominous issue is transmission of noise from transiting vessels and how this noise affects marine mammals. The tools used to analyse and define the expected levels of vibration and noise in the design phase are becoming more and more robust. The paper describes the use of computational fluid dynamics to predict the noise and vibration generated by hydrodynamic flow over the hull and the propeller(s) of the vessel. The analysis is carried out using the program OpenFOAM comparing the operating propeller performance coefficients with the open water propeller coefficients. The paper also looks at the effects of cavitation, vessel trim and propeller loading on a 140 meter car ferry. The loading, noise and vibration data will be quantified and compared to full scale vessel data.

A Research Project on Application of Air Bubble Injection to a Full Scale Ship for Drag Reduction

2007 ◽  
Author(s):  
Hideki Kawashima ◽  
Yoshiaki Kodama ◽  
Munehiko Hinatsu ◽  
Toshifumi Hori ◽  
Masahiko Makino ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Drag Reduction ◽  
Flat Plate ◽  
Full Scale ◽  
Air Bubbles ◽  
Research Project ◽  
Air Bubble ◽  
Full Scale Experiment ◽  
Scale Experiment ◽  
Propeller Performance

This paper is a progress report of a research project toward practical use of air bubble injection as a drag reduction device for ships. Air bubbles injected into the turbulent boundary layer in water flow are well known to have significant skin friction reduction effect. The current research project will last for three years, starting in April 2005. The project aims at obtaining 10% net energy-saving by air bubble injection, taking into account the work needed for injecting air bubbles. A full scale experiment is scheduled in September 2007. The photo and principal particular of the ship used for the full scale experiment are shown in Figure 1 and Table 1. The ship has a wide and flat bottom. Therefore, once air bubbles are injected at the bottom near the bow, they are expected to cover the entire bottom surface efficiently. The air bubbles must be injected against the hydrostatic pressure at the point of injection. Estimation of the rate of drag reduction per unit amount of injected air at full scale is extremely difficult if it is based on small model-scale experiments, because the scale ratio of air bubbles to boundary layer length scales is very different between model and full scale experiments. Therefore we carried out experiments using a flat plate (L = 50m, B = 1m) in the 400m towing tank of the institute. The plate was towed at 6.2m/s (12kt), the cruising speed of the ship for a full scale experiment. Air bubbles were injected at 3m from the bow. Both the total drag of the flat plate and local skin friction were measured. Recently we attached end plates almost along the entire length, in order to prevent air bubbles from getting lost from the sides, and obtained significant improvement in drag reduction. Injected air bubbles are expected to go into the propeller operating at the stern and the propeller performance may deteriorate. Therefore we carried out tests of a model propeller working in bubbly flow. So far we found that the degradation of the propeller performance due to bubbles is small and tolerable. The project is carried out in collaboration with Osaka Univ., Hokkaido Univ., Tokyo Univ., Mitsui Engineering & Shipbuilding CO., LTD. and Azuma Shipping CO., LTD.. The project is funded by NEDO (New Energy and Industrial Technology Development Organization), Japan.

Relation of Statistically Significant, Abnormal, and Typical WAIS-R VIQ-PIQ Discrepancies to Full Scale IQs

2000 ◽  
Vol 16 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Louis M. Hsu ◽  
Judy Hayman ◽  
Judith Koch ◽  
Debbie Mandell
Keyword(s):  
Graphical Method ◽  
The United States ◽  
Full Scale ◽  
True Score ◽  
Absolute Value ◽  
Normative Population ◽  
The Us ◽  
The Mean ◽  
And Performance ◽  
Quadratic Models

Summary: In the United States' normative population for the WAIS-R, differences (Ds) between persons' verbal and performance IQs (VIQs and PIQs) tend to increase with an increase in full scale IQs (FSIQs). This suggests that norm-referenced interpretations of Ds should take FSIQs into account. Two new graphs are presented to facilitate this type of interpretation. One of these graphs estimates the mean of absolute values of D (called typical D) at each FSIQ level of the US normative population. The other graph estimates the absolute value of D that is exceeded only 5% of the time (called abnormal D) at each FSIQ level of this population. A graph for the identification of conventional “statistically significant Ds” (also called “reliable Ds”) is also presented. A reliable D is defined in the context of classical true score theory as an absolute D that is unlikely (p < .05) to be exceeded by a person whose true VIQ and PIQ are equal. As conventionally defined reliable Ds do not depend on the FSIQ. The graphs of typical and abnormal Ds are based on quadratic models of the relation of sizes of Ds to FSIQs. These models are generalizations of models described in Hsu (1996) . The new graphical method of identifying Abnormal Ds is compared to the conventional Payne-Jones method of identifying these Ds. Implications of the three juxtaposed graphs for the interpretation of VIQ-PIQ differences are discussed.

A Modification of the Payne-Jones Method of Identifying Abnormal Differences in WISC-R Performance and Verbal IQ's

1996 ◽  
Vol 12 (1) ◽  
pp. 27-32 ◽  
Author(s):  
Louis M. Hsu
Keyword(s):  
Full Scale ◽  
True Score ◽  
Verbal Iq ◽  
Score Difference ◽  
The Difference ◽  
And Performance

The difference (D) between a person's Verbal IQ (VIQ) and Performance IQ (PIQ) has for some time been considered clinically meaningful ( Kaufman, 1976 , 1979 ; Matarazzo, 1990 , 1991 ; Matarazzo & Herman, 1985 ; Sattler, 1982 ; Wechsler, 1984 ). Particularly useful is information about the degree to which a difference (D) between scores is “abnormal” (i.e., deviant in a standardization group) as opposed to simply “reliable” (i.e., indicative of a true score difference) ( Mittenberg, Thompson, & Schwartz, 1991 ; Silverstein, 1981 ; Payne & Jones, 1957 ). Payne and Jones (1957) proposed a formula to identify “abnormal” differences, which has been used extensively in the literature, and which has generally yielded good approximations to empirically determined “abnormal” differences ( Silverstein, 1985 ; Matarazzo & Herman, 1985 ). However applications of this formula have not taken into account the dependence (demonstrated by Kaufman, 1976 , 1979 , and Matarazzo & Herman, 1985 ) of Ds on Full Scale IQs (FSIQs). This has led to overestimation of “abnormality” of Ds of high FSIQ children, and underestimation of “abnormality” of Ds of low FSIQ children. This article presents a formula for identification of abnormal WISC-R Ds, which overcomes these problems, by explicitly taking into account the dependence of Ds on FSIQs.

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