scholarly journals Numerical Study of Hub Taper Angle on Podded Propeller Performance

2006 ◽  
Vol 43 (01) ◽  
pp. 1-10
Author(s):  
Mohammed F. Islam ◽  
Brian Veitch ◽  
Neil Bose ◽  
Pengfei Liu
Keyword(s):  
Numerical Study ◽  
Open Water ◽  
Propulsion Systems ◽  
Taper Angle ◽  
Propulsive Performance ◽  
Pressure Distributions ◽  
Overall Performance ◽  
The Difference ◽  
Propeller Blades ◽  
Propeller Performance

Presently, the majority of podded propulsion systems are of the pulling type, because this type provides better hydrodynamic efficiency than the pushing type. There are several possible explanations for the better overall performance of a puller-type podded propulsor. One is related to the difference in hub taper angle. Puller and pusher propellers have opposite hub taper angles, hence different hub and blade root shape. These differences cause changes in the flow condition and possibly influence the overall performance. The current study focuses on the variation in performance of pusher and puller propellers with the same design of blade sections, but different hub taper angles. A hyperboloidal low-order source-doublet steady/unsteady time domain panel method code, PROPELLA, was modified and used to evaluate effects of hub taper angle on the open water propulsive performance of some fixed-pitch screw propellers used in podded propulsion systems. Major findings include good agreement between predictions using the modified code and measurements, significant effects of hub taper angle on propulsive performance of tapered hub propellers, and noticeable effects of hub taper angle on sectional pressure distributions of tapered hub propeller blades.

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.

Numerical and Experimental Research on a Podded Propulsor

2014 ◽  
Author(s):  
Mohammed Islam ◽  
Ron Ryan ◽  
David Molynuex
Keyword(s):  
Preliminary Analysis ◽  
Numerical Study ◽  
Open Water ◽  
Navier Stokes ◽  
Experimental Program ◽  
Propulsive Performance ◽  
Podded Propulsor ◽  
Thrust And Torque ◽  
Straight Ahead ◽  
Experimental Effort

This paper presents methodologies and some results of a numerical and experimental program to evaluate the effects of static azimuthing conditions on the propulsive characteristics of a puller podded propulsor in open water. In the experimental effort, the model propulsor was instrumented to measure thrust, torque and rotational speed of the propeller, and three orthogonal forces and moments, and azimuthing angle of the pod. The experimental results included the bare propeller (ahead only) and the combined propeller and pod over a range of advance coefficients at various static azimuthing angles in the range of −180° to 180°. A complementary numerical study is being carried out to predict the hydrodynamic forces of podded propulsor in static azimuthing conditions. A Reynolds-Averaged Navier Stokes solver is used to predict the propulsive performance of the bare propeller as well as the podded propulsor system. The thrust and torque for the bare propeller were compared to the corresponding measurements. The propeller thrust and torque as well as the loads on the pod in straight-ahead condition and at static azimuthing angles were then compared with the measurements. Preliminary analysis demonstrates that the RANS solver could predict the performance coefficients of the bare propeller as well as the podded propulsor in straight-ahead and static azimuthing angles in puller configurations.

scholarly journals Experimental research on marine podded propulsors

1970 ◽  
Vol 4 (2) ◽  
pp. 57-71 ◽  
Author(s):  
Mohammed F Islam ◽  
Brian Veitch ◽  
Pengfei Liu
Keyword(s):  
Open Water ◽  
Hydrodynamic Performance ◽  
Prediction Methods ◽  
Taper Angle ◽  
Propulsive Performance ◽  
Water Conditions ◽  
Cavitation Tunnel ◽  
Experimental Side ◽  
Marine Engineering ◽  
Thrust And Torque

This paper describes a research program on podded propulsors that combines parallel developments in numerical prediction methods and experimental evaluation. Amongst the hydrodynamic issues that have been identified and addressed are questions regarding the effects of hub taper angle, pod-strut configurations, static azimuthing conditions, pod-strut interactions, gap pressure, pod gap and pod-strut geometry on podded propulsors' performance. On the experimental side, a pod dynamometer system consisting of a six-component global dynamometer and a three-component pod dynamometer were designed, manufactured and used to perform measurements on propeller thrust and torque and unit forces and moments in the three orthogonal directions in pusher and puller configurations in open water conditions. Four propellers with the same blade sections but different hub taper angles were designed and used to fit with eighteen pod-strut shells. Among the shells, two pod-strut models were based on the average dimensions of commercial pods and used to study the hub angle, pod configuration, pod gap, gap pressure and azimuthing conditions effect on propulsive performance. The other sixteen pods were designed and manufactured to study the effect of five geometric parameters on hydrodynamic performance using a design of experiments technique. In another study, an experimental method was implemented in a cavitation tunnel to evaluate the wake/strut interaction of a podded propeller model. All of the measurements showed consistency.DOI: http://dx.doi.org/10.3329/jname.v4i2.989 Journal of Naval Architecture and Marine Engineering Vol.4(2) 2007 p 57-71

Experimental Study and Numerical Simulation on Hydrodynamic Performance of a Twisted Rudder

2015 ◽  
Vol 49 (5) ◽  
pp. 58-69 ◽  
Author(s):  
Yu Sun ◽  
Yu-min Su ◽  
Hai-zhou Hu
Keyword(s):  
Numerical Simulation ◽  
Energy Saving ◽  
Open Water ◽  
Hydrodynamic Performance ◽  
Surface Panel Method ◽  
Thrust Coefficient ◽  
Propeller Wake ◽  
Pressure Distributions ◽  
The Difference ◽  
Saving Effect

AbstractTo analyze the energy-saving effect of a twisted rudder, this work presents the simulated and experimental results of propeller-rudder systems. In this article, a surface panel method (SPM) and computational fluid dynamics (CFD) are introduced to simulate the hydrodynamic performance of propeller-rudder systems. The thrust coefficient Kt, torque coefficient Kq, open-water efficiency η of the propeller, and thrust coefficient Kr of the rudder as a function of the advance coefficient J are obtained and plotted. The energy-saving effect of the twisted rudder is analyzed by comparing the results of numerical simulation and a cavitation tunnel experiment. The experimental energy-saving effect is 2.23% at the design advance coefficient J = 0.8. The pressure distributions of the propeller blade and rudder are plotted by two methods, and the difference of the force on an ordinary rudder and a twisted rudder is discussed. This study improved the experimental twisted rudder model. The change makes the rudder take advantage of propeller wake and improves the energy-saving effect of a twisted rudder. After improvement, the energy-saving effects obtained by the two methods are 0.448% and 0.441%. To analyze the energy-saving mechanism, this study compares the pressure distributions and efficiencies of different systems.

Recent Developments in Computational Methods for the Analysis of Ducted Propellers in Open Water

2019 ◽  
Vol 63 (4) ◽  
pp. 219-234
Author(s):  
João Baltazar ◽  
José A. C. Falcão de Campos ◽  
Johan Bosschers ◽  
Douwe Rijpkema
Keyword(s):  
Computational Methods ◽  
Open Water ◽  
Boundary Element Methods ◽  
Navier Stokes ◽  
Hydrodynamic Analysis ◽  
Numerical Predictions ◽  
Ducted Propeller ◽  
Recent Developments ◽  
Propeller Performance ◽  
Ducted Propellers

This article presents an overview of the recent developments at Instituto Superior Técnico and Maritime Research Institute Netherlands in applying computational methods for the hydrodynamic analysis of ducted propellers. The developments focus on the propeller performance prediction in open water conditions using boundary element methods and Reynolds-averaged Navier-Stokes solvers. The article starts with an estimation of the numerical errors involved in both methods. Then, the different viscous mechanisms involved in the ducted propeller flow are discussed and numerical procedures for the potential flow solution proposed. Finally, the numerical predictions are compared with experimental measurements.

scholarly journals Aerodynamic Inverse Design of Transonic Compressor Cascades with Stabilizing Elastic Surface Algorithm

2021 ◽  
Vol 11 (11) ◽  
pp. 4845
Author(s):  
Mohammad Hossein Noorsalehi ◽  
Mahdi Nili-Ahmadabadi ◽  
Seyed Hossein Nasrazadani ◽  
Kyung Chun Kim
Keyword(s):  
Design Method ◽  
Inverse Design ◽  
Normal Shock ◽  
Compressor Cascade ◽  
Elastic Surface ◽  
Transonic Compressor ◽  
Pressure Distributions ◽  
The Difference ◽  
Inverse Design Method ◽  
Transonic Cascade

The upgraded elastic surface algorithm (UESA) is a physical inverse design method that was recently developed for a compressor cascade with double-circular-arc blades. In this method, the blade walls are modeled as elastic Timoshenko beams that smoothly deform because of the difference between the target and current pressure distributions. Nevertheless, the UESA is completely unstable for a compressor cascade with an intense normal shock, which causes a divergence due to the high pressure difference near the shock and the displacement of shock during the geometry corrections. In this study, the UESA was stabilized for the inverse design of a compressor cascade with normal shock, with no geometrical filtration. In the new version of this method, a distribution for the elastic modulus along the Timoshenko beam was chosen to increase its stiffness near the normal shock and to control the high deformations and oscillations in this region. Furthermore, to prevent surface oscillations, nodes need to be constrained to move perpendicularly to the chord line. With these modifications, the instability and oscillation were removed through the shape modification process. Two design cases were examined to evaluate the method for a transonic cascade with normal shock. The method was also capable of finding a physical pressure distribution that was nearest to the target one.

Experimental and Numerical Study on Grinding Temperature during Surface Grinding with Different Cooling Methods

2009 ◽  
Vol 416 ◽  
pp. 514-518 ◽  
Author(s):  
Qing Long An ◽  
Yu Can Fu ◽  
Jiu Hua Xu
Keyword(s):  
Numerical Study ◽  
Specific Energy Consumption ◽  
Ground Surface ◽  
Numerical Results ◽  
Surface Grinding ◽  
Grinding Temperature ◽  
Air Jet ◽  
The Difference ◽  
High Specific Energy ◽  
Cooling Methods

Grinding, characterized by its high specific energy consumption, may generate high grinding zone temperature. These can cause thermal damage to the ground surface and poor surface integrity, especially in the grinding of difficult-to-machine materials. In this paper, experimental and fem study on grinding temperature during surface grinding of Ti-6Al-4V with different cooling methods. A comparison between the experimental and numerical results is made. It is indicated that the difference between experimental and numerical results is below 15% and the numerical results can be considered reliable. Grinding temperature can be more effectively reduced with CPMJ than that with cold air jet and flood cooling method.

Bejan’s Constructal Theory Analysis of Gas-Liquid Cooled Finned Modules

2011 ◽  
Vol 133 (7) ◽  
Author(s):  
Giulio Lorenzini ◽  
Simone Moretti
Keyword(s):  
Thermal Behavior ◽  
Heat Exchangers ◽  
High Performance ◽  
Numerical Study ◽  
Constructal Theory ◽  
Electronic Components ◽  
Theory Analysis ◽  
Pressure Losses ◽  
Different Types ◽  
Overall Performance

High performance heat exchangers represent nowadays the key of success to go on with the trend of miniaturizing electronic components as requested by the industry. This numerical study, based on Bejan’s Constructal theory, analyzes the thermal behavior of heat removing fin modules, comparing their performances when operating with different types of fluids. In particular, the simulations involve air and water (as representative of gases and liquids), to understand the actual benefits of employing a less heat conductive fluid involving smaller pressure losses or vice versa. The analysis parameters typical of a Constructal description (such as conductance or Overall Performance Coefficient) show that significantly improved performances may be achieved when using water, even if an unavoidable increase in pressure losses affects the liquid-refrigerated case. Considering the overall performance: if the parameter called Relevance tends to 0, air prevails; if it tends to 1, water prevails; if its value is about 0.5, water prevails in most of the case studies.

Experimental and Numerical Study of Micro-Aerial-Vehicle Propeller Performance in Oblique Flow

2017 ◽  
Vol 54 (3) ◽  
pp. 1076-1084 ◽  
Author(s):  
B. Theys ◽  
G. Dimitriadis ◽  
P. Hendrick ◽  
J. De Schutter
Keyword(s):  
Numerical Study ◽  
Micro Aerial Vehicle ◽  
Oblique Flow ◽  
Aerial Vehicle ◽  
Propeller Performance

Wave Pressure Distributions Along the Midship Transverse Section of a VLCC

2008 ◽  
Author(s):  
Zhi Shu ◽  
Torgeir Moan
Keyword(s):  
Transverse Section ◽  
Roll Damping ◽  
Wave Pressure ◽  
Ship Hulls ◽  
Pressure Distributions ◽  
The Difference ◽  
Hydrodynamic Code ◽  
Long Term Prediction ◽  
External Wave

The external wave pressure distributions along the transverse section in the midship region of a VLCC are evaluated in this paper. The commercial hydrodynamic code WASIM issued by DnV has been adopted to perform the hydrodynamic computation. The ship hulls have been discretized with coarser and finer mesh to investigate the effect of panel size on the hydrodynamic pressures. It is found that the difference between these two mesh finenesses is small. It is also found that the roll damping has a significant influence on the wave pressure of vessel especially in beam sea. A sensitivity analysis is carried out in the sense of assessing the influence of the roll damping on the wave pressure. Finally, the long term prediction of the wave pressure has been compared for different roll damping values.

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