Numerical Prediction of Propeller Characteristics

1973 ◽  
Vol 17 (01) ◽  
pp. 12-18
Author(s):  
Damon E. Cummings
Keyword(s):  
Open Water ◽  
Model Tests ◽  
Numerical Prediction ◽  
Water Model ◽  
Variable Pitch ◽  
Cavitation Inception ◽  
Fraction Distribution ◽  
Thrust And Torque ◽  
Ship Speed

A procedure is described for predicting the performance of a propeller numerically to within the accuracy of tunnel and open-water model tests. Given the geometry of the propeller, ship speed, wake fraction distribution and rpm, the thrust and torque characteristics are calculated. The procedure gives good results not only for "normal" propellers but also for such abnormal cases as a variable-pitch propeller operating at off-design pitches. The possibility exists of extension of the method for calculation of spindle torques, stresses, and cavitation inception.

Double Acting Tanker: Experiences from Model Tests and Sea Trials

2005 ◽  
Vol 219 (3) ◽  
pp. 109-119 ◽  
Author(s):  
P Trägärdh ◽  
P Lindell ◽  
N Sasaki
Keyword(s):  
Model Test ◽  
Oil And Gas ◽  
Single Point ◽  
Open Water ◽  
Model Tests ◽  
Water Model ◽  
Research Centre ◽  
Sea Trial ◽  
Cavitation Performance ◽  
Ice Conditions

The acronym DAT stands for double acting tanker, a concept where the ship is designed to run astern in heavy ice conditions while remaining hydrodynamically efficient for ahead propulsion in open water conditions. Two large aframax DATs - 106.000 dwt (deadweight tons) each - have been delivered by Sumitomo Heavy Industries to Fortum Oil and Gas OY. They are the first crude carriers built according to the DAT principle and also the first using pod propulsion from the beginning (Fig. 1). They will also be the world's largest crude carriers with ice class 1A super and are primarily intended for year-round transportation of North Sea crude to Fortum's refineries in the Gulf of Finland. The ships were appointed ‘ship of the year’ in Japan in 2003. SSPA was contracted by Sumitomo Heavy Industries to perform model tests. A comprehensive open water model test programme was used to investigate aspects of resistance and propulsion, manoeuvring, and cavitation performance. As the ship is designed to operate both in ahead and astern conditions for prolonged periods of time, most tests were performed both ahead and astern. Also, a simulation study of dynamic positioning at buoy or floating production, storage offshore (FPSO) loading was made by SSPA. Comprehensive tests of the ship's performance in ice were performed in the ice tank at MARC (Masa-Yards Artic Research Centre). The eight-month model testing and development campaign resulted in a ship with excellent propulsion and manoeuvring performance, especially with regard to the high ice class. Sea trials carried out with ship in August 2002 confirmed the results of the model test. Interesting experiences of the model test campaign and comparison between model test and sea trial results are presented, as well as some examples of single-point mooring simulations.

scholarly journals Prediction of Propeller Performance Using Computational Fluid Dynamics Approach

2019 ◽  
Vol 2 (2) ◽  
pp. 185-193
Author(s):  
Nur Amira Adam ◽  
Ahmad Fitriadhy ◽  
W. S. Kong ◽  
Faisal Mahmuddin ◽  
C. J. Quah
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Open Water ◽  
Water Model ◽  
Thrust Coefficient ◽  
Propeller Performance ◽  
Prediction Approach ◽  
Thrust And Torque

A reliable prediction approach to obtain a sufficient thrust and torque to propel the ship at desired forward speed is obviously required. To achieve this objective, the authors propose to predict the thrust coefficient (KT), torque coefficient (KQ) and efficiency (η) of the propeller in open-water model test condition using Computational Fluid Dynamics (CFD) simulation approach. The computational simulation presented in the various number of rotational speed (RPM) within the range of advance ratio J=0.1 up to 1.05. The higher value of J lead to decrease 10KQ and KT. While the η increased steadily at the lower value of J and decreased at the higher value of J. The results also showed that the propeller with 1048 rpm obtain a better efficiency at J=0.95 with η= 88.25%, 10KQ=0.1654 and KT= 0.0942. The computation result is very useful as preliminary data for propeller performance characteristics.

Thruster-Wave Interaction During DP Stationkeeping: Model Tests in Open Water and Under a Ship Hull

2017 ◽  
Author(s):  
Hans Cozijn ◽  
Jin Woo Choi ◽  
Young-Jun You
Keyword(s):  
Wave Interaction ◽  
Open Water ◽  
Model Tests ◽  
Wave Frequency ◽  
Scale Model ◽  
Regular Wave ◽  
Physical Scale ◽  
Torque Values ◽  
Thrust And Torque ◽  
Change In Mean

Wave orbital motions may cause variations in the inflow conditions of thrusters, resulting in variations in thrust and torque. Physical scale model tests were carried out to investigate these thruster-wave interaction effects, with an azimuthing thruster running at constant RPMs. The observed effects include a change in mean thrust and torque values, as well as wave frequency variations. The test conditions were systematically varied to investigate the effects of the incoming waves, the presence of the hull and the vessel motions. First, measurements were carried out on an azimuthing thruster in open water conditions. The thrust and torque in regular waves were compared with bollard pull conditions. Second, measurements were carried out on the azimuthing thruster under the hull of a vessel, which was rigidly connected to the basin carriage. Again, regular wave tests were performed, showing the effect of the presence of the hull. Third, measurements were carried out on the same azimuthing thruster under the hull of the vessel in a soft-mooring system. This kept the vessel in position and at the required heading, while allowing unrestricted wave frequency motions. Again, regular wave tests were performed, now showing the combined effects of the passing waves, the presence of the vessel hull and the vessel motions.

THE EFFECT OF LEEWAY ANGLE ON THE PROPELLER PERFORMANCE

2019 ◽  
Author(s):  
J. J. A. Schot ◽  
R Eggers
Keyword(s):  
Prediction Method ◽  
Model Tests ◽  
Design Stage ◽  
Propulsive Efficiency ◽  
Single Screw ◽  
Captive Model Tests ◽  
Twin Screw ◽  
Propeller Performance ◽  
Thrust And Torque ◽  
Ship Speed

One of the aspects influencing the performance of wind assisted vessels is the effect of leeway (drift) angle on the propeller performance. It is known that due to leeway the delivered propeller power and propulsive efficiency can vary significantly from the straight sailing condition. This effect of leeway angle is studied using a combination of viscous flow calculations and captive model tests for one twin screw and three single screw vessels. It is observed that the changes in mean axial velocity and pre-swirl rotation in the wakefield due to a combination of leeway angle and propeller suction are sufficient to describe the trends observed in captive model tests. This knowledge is used in a proposed prediction method to model the changes in propeller thrust and torque due to leeway angle at the design stage. The prediction model combined with a fit of the average wake parameters for the studied vessel types is finally used the show the trends in propulsive efficiency and delivered propeller power at constant propeller rotation rate and ship speed for small leeway angles.

Optimization of RANS Solver Simulation Setup for Propeller Open Water Performance Prediction

2015 ◽  
Author(s):  
Mohammed Islam ◽  
Fatima Jahra ◽  
Michael Doucet
Keyword(s):  
Domain Size ◽  
Open Water ◽  
Fractional Factorial ◽  
Navier Stokes ◽  
Calm Water ◽  
Simulation Results ◽  
Open Water Performance ◽  
Thrust And Torque ◽  
Simulation Time ◽  
Fixed Pitch

Mesh and domain optimization strategies for a RANS solver to accurately estimate the open water propulsive characteristics of fixed pitch propellers are proposed based on examining the effect of different mesh and computation domain parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations to be carried out in a limited memory environment, and in a timely manner; without compromising the accuracy of results. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of a fixed pitch propeller. The predicted thrust and torque for the propeller were compared to the corresponding measurements. A total of six meshing parameters were selected that could affect the computational results of propeller open water performance. A two-level fractional factorial design was used to screen out parameters that do not significantly contribute to explaining the dependent parameters: namely simulation time, propeller thrust and propeller torque. A total of 32 simulations were carried out only to find out that the selected six meshing parameters were significant in defining the response parameters. Optimum values of each of the input parameters were obtained for the DOE technique and additional simulations were run with those parameters. The simulation results were validated using open water experimental results of the same propeller. It was found that with the optimized meshing arrangement, the propeller opens simulation time was reduced by at least a factor of 6 as compared to the generally popular meshing arrangement. Also, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using STAR-CCM+, a commercial CFD package; however the findings can be applied to any RANS solver.

Model Tests in Brash Ice Channels

2005 ◽  
Author(s):  
Jens-Holger Hellmann ◽  
Karl-Heinz Rupp ◽  
Walter L. Kuehnlein
Keyword(s):  
Perforated Plate ◽  
Ice Sheet ◽  
Open Water ◽  
Model Tests ◽  
Ice Thickness ◽  
Special Device ◽  
Level Ice ◽  
Set Up ◽  
Parental Level ◽  
Oil Tankers

According to the present Finnish-Swedish Ice Class Rules (FSICR) the formulas for the required main engine power for tankers led to much bigger main engines than it is needed for the demanded open water speed. Therefore model tests may be performed in order to verify the vessel’s capability to sail with less required power in brash ice channels compared to the calculations. Several model test runs have been performed in order to study the performance of crude oil tankers sailing in brash ice. The tests were performed as towed propulsion tests and the brash ice channel was prepared according to the guidelines set up by the Finnish Maritime Administration (FMA). The channel width was 2 times the beam of the tanker. The model tests were carried out at a speed of 5 knots. For the tests a parental level ice sheet of adequate thickness is prepared according to HSVA’s standard model ice preparation procedure. After a predefined level ice thickness has been reached, the air temperature in the ice tank will be raised. An ice channel with straight edges will be cut into the ice sheet by means of two ice knives. The ice stripe between the two cuts will be manually broken up into relatively small ice pieces using a special ice chisel and if required the brash ice material will be compacted. Typically the brash ice thickness will be measured prior the tests at 9 positions across the channel and every two meter over the entire length of the brash ice channel with a special device, which consists of a measuring rule with a perforated plate mounted under a right angle at the lower end of the rule. As a result of the tests it could be demonstrated that tankers with a capacity of more than 50 000 tons require 50% and even less power compared to calculations using the present FSICR formulas.

Experimental Performance of a Trochoidal Propeller with High-Aspect-Ratio Blades

1989 ◽  
Vol 26 (03) ◽  
pp. 192-201 ◽  
Author(s):  
Neil Bose ◽  
Peter S. K. Lai
Keyword(s):  
Aspect Ratio ◽  
High Efficiency ◽  
Open Water ◽  
Finite Amplitude ◽  
Dynamic Stall ◽  
Frictional Drag ◽  
Overall Performance ◽  
Small Ship ◽  
Propeller Performance ◽  
Thrust And Torque

Open-water experiments were done on a model of a cycloidal-type propeller with a trochoidal blade motion. This propeller had three blades with an aspect ratio of 10. These experiments included the measurement of thrust and torque of the propeller over a range of advance ratios. Tests were done for forward and reverse operation, and at zero speed (the bollard pull condition). Results from these tests are presented and compared with: a multiple stream-tube theoretical prediction of the performance of the propeller; and a prediction of the performance of a single blade of the propeller, oscillating in heave and pitch, using unsteady small-amplitude hydrofoil theory with corrections for finite amplitude motion, finite span, and frictional drag. At present, neither of these theories gives a completely accurate prediction of propeller performance over the whole range of advance ratios, but a combination of these approaches, with an allowance for dynamic stall of the blades, should lead to a reliable simple theory for overall performance prediction. Application of a propeller of this type to a small ship is discussed. The aim of the design is to produce a lightly loaded propeller with a high efficiency of propulsion.

Comparison of Stopping Modes for Pod-Driven Ships by Simulation Based on Model Testing

2005 ◽  
Vol 219 (2) ◽  
pp. 47-64 ◽  
Author(s):  
M D Woodward ◽  
M Atlar ◽  
D Clarke
Keyword(s):  
Load Condition ◽  
Open Water ◽  
Water Model ◽  
Simulation Algorithm ◽  
Time Domain Simulation ◽  
Dynamic Effects ◽  
Study Results ◽  
Simulation Based ◽  
Fluid Damping

Conventionally, the stopping of a ship is achieved by direct reversal of propeller rotation. However, the introduction of azimuthing pods presents other options. The following study examines the various modes that may be employed to stop a pod-driven ship. A continuous function is derived describing the hydrodynamic forces on both the propeller and the pod body for any load condition and helm angle, including fluid damping and added mass effects. The proposed function is validated through comparison with comprehensive open water model tests. Next, a time domain simulation algorithm is proposed to examine the dynamic effects including the mass inertia on both the propeller shaft and slewing stock. Finally, a simulation study for the proposed stopping modes is performed using a known design as a case study. Results and discussion are presented.

Numerical investigation of the rake angle effect on the hydrodynamic performance of propeller in a uniform and nonuniform flow

2019 ◽  
Vol 233 (18) ◽  
pp. 6326-6338
Author(s):  
Hasan Sajedi ◽  
Miralam Mahdi
Keyword(s):  
Open Water ◽  
Rake Angle ◽  
Uniform Flow ◽  
Wake Flow ◽  
Hydrodynamic Performance ◽  
Experimental Result ◽  
Nonuniform Flow ◽  
Solution Scheme ◽  
Propeller Performance ◽  
Thrust And Torque

Marine propeller always operates in the wake of a vehicle (ship, torpedo, submarine) but (due to the high computational cost of simulating vehicle and propeller simultaneously) to investigate the propeller geometric parameters, simulations are usually performed in open-water conditions. In this article, using the computational fluid dynamics method with the control volume approach, the effect of the rake angle on the propeller performance and formation of cavitation in the uniform flow (open water) and the nonuniform flow (wake flow) was investigated. In the nonuniform condition, the array of plates was used to simulate wake at upstream propeller. For uniform flow, steady solution scheme was adopted and for nonuniform flow unsteady solution scheme was adopted, and a moving mesh zone was generated around the propeller. To simulate cavitation a multiphase mixture flow, the Reynolds-averaged Navier–Stokes method was used and modeled by Schnerr Sauer's cavitation model. First, the E779a propeller model for numerical validation in the uniform flow and nonuniform flow was investigated. Numerical results were compared with the experimental result, and there was a good agreement between volume of the cavity, thrust, and torque coefficients. To study the effect of rake angle on the performance of B-series propellers, four models with different rake angles were modeled, and simulation was investigated behind the wake. The results of thrust, torque coefficients, and cavitation volume according to the flow parameters and cavitation number were presented as graphs. The results reveals that in the uniform flow, the rake angle has no significant effect on the propeller performance, but behind the wake flow, increase of rake causes to reduce the force applied to the propeller blades, cavitation volume, and pressure fluctuations on the propeller.

scholarly journals Surprising Behaviour of the Wageningen B-Screw Series Polynomials

2020 ◽  
Vol 8 (3) ◽  
pp. 211 ◽  
Author(s):  
Stephan Helma
Keyword(s):  
Reynolds Number ◽  
Open Water ◽  
Measured Data ◽  
Design Stage ◽  
Data Sets ◽  
Preliminary Design ◽  
Preliminary Design Stage ◽  
Torque Values ◽  
Thrust And Torque ◽  
Over Time

Undoubtedly, the Wageningen B-screw Series is the most widely used systematic propeller series. It is very popular to preselect propeller dimensions during the preliminary design stage before performing a more thorough optimisation, but in the smaller end of the market it is often used to merely select the final propeller. Over time, the originally measured data sets were faired and scaled to a uniform Reynolds number of 2 · 106 to increase the reliability of the series. With the advent of the computer, polynomials for the thrust and torque values were calculated based on the available data sets. The measured data are typically presented in the well-known open-water curves of thrust and torque coefficients K T and K Q versus the advance coefficient J . Changing the presentation from these diagrams to efficiency maps reveals some unsuspected and surprising behaviours, such as multiple extrema when optimising for efficiency or even no optimum at all for certain conditions, where an optimum could be expected. These artefacts get more pronounced at higher pitch to diameter ratios and low blade numbers. The present work builds upon the paper presented by the author at the AMT’17 and smp’19 conferences and now includes the extended efficiency maps, as suggested by Danckwardt, for all propellers of the Wageningen B-screw Series.

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