Hydrodynamic Performance Of Propeller Research Articles

Non-uniform inlet flow definition for highly skewed model propeller by geometric partitioning

Ship design involves many calculations to provide a propulsion system with the appropriate speed. Prioritizing speed-resistance calculations affects main engine, gearbox, propeller, and other auxiliary system selection. Here, the propeller is most intriguing. Since the propeller operates in a fluid domain, internal and external factors affect it. Despite being designed for service speed, water flow can affect the efficiency of a propeller at the ship's stern. Under open-water circumstances, a ship's hull affects a propeller's hydrodynamic performance. The effect usually decreases propeller efficiency, so it's important to know how ship hull and propeller design interact before production. To overcome this issue, researchers test towing tanks extensively. Computational Fluid Dynamics, which is efficient and cost-effective, is also commonly used. This study examines the hydrodynamics of a fishing vessel's highly skewed model propeller. The objective of this study was to assess the propeller's efficiency under uniform and non-uniform flow conditions and investigate an alternative method for dividing the inlet area, which has not been studied in the literature. The study has effectively met its goals, producing satisfactory error margins for both operating conditions. This research significantly contributes to understanding the relationship between hull configuration and propeller design, particularly in non-uniform flow scenarios.

Research on the hydrodynamic performance of propellers under oblique flow conditions

The phenomenon of oblique water inflow is widespread in the operation of thrusters, which will cause adverse effects on the hydrodynamic performance of thrusters. In order to investigate the hydrodynamic performance and stress variation of the propeller in oblique flow, based on computational fluid dynamics theory, this paper takes the DTMB4119 propeller as the research object and conducts numerical simulation research on the propeller in oblique flow by solving the RANS equation. By calculating the open water performance curve and surface pressure distribution of the propeller, the rationality of the numerical method and the meshing are verified. Considering the flow field information such as velocity, oblique flow angles, flow line distribution, and pressure distribution, the changes in hydrodynamic characteristics of the propeller are simulated and analyzed. The results show that the uneven distribution of pressure on the propeller blade surface increases with a decrease in the advance coefficient. The force pulsation amplitude of a single blade increases with an increase in oblique flow angles. With the increase in oblique flow angles, the thrust, torque, and efficiency of the propeller show different increasing trends. With the increase in propeller advance coefficient, propeller thrust and torque decrease gradually, and propeller efficiency increases gradually. By using mature propellers, this paper has more reference value for studying the flow field around the ship hull and the hydrodynamic performance of propellers in the process of ship maneuvering.

Hydrodynamic Performance of Cycloidal Propellers with Four-Bar and Mixed Four-bar/Five-bar Mechanisms: A Numerical Study

Cycloidal propellers constitute a specialized category of underwater propulsion devices, widely employed in vehicles requiring exceptional maneuverability. The parameters of the blade-driving mechanism directly impact the propeller performance. Hence, the effect of variations in the geometric parameters of the blade-driving mechanism on the hydrodynamic performance of cycloidal propellers must be investigated. In this study, a specific set of four-bar and mixed four-bar/five-bar mechanisms are taken as examples, and the effect of linkage-length variations on the hydrodynamic performance of cycloidal propellers was analyzed using numerical simulation methods. First, we established a physical model of the cycloidal propeller, and then derived the relationship between blade-rotation and revolution angles. Subsequently, by solving the Navier–Stokes equations and employing computational fluid dynamics simulations based on viscosity, an analysis is conducted to reveal the trends in the impact of different linkage-length combinations on the hydrodynamic performance of the cycloidal propeller. Finally, the outcomes of the numerical simulations are interpreted using the wing element theory. In similar blade-driving mechanisms, the effects of varying linkage lengths on propeller hydrodynamic performance are determined through alterations in the blade rotation angle range and equilibrium position. An increase in the range of the blade-rotation angle significantly enhances the hydrodynamic performance of the cycloidal propeller. This research employs a more realistic auto-propulsion mode for numerical simulations, establishing a mapping relationship between the blade-driving mechanism and hydrodynamic performance of the cycloidal propeller, while analyzing the underlying influencing mechanisms. Furthermore, crucial numerical simulations and theoretical foundations are employed for designing the four-bar and mixed four-bar/five-bar mechanism cycloidal propellers. The findings of this study could also be used in similar cycloidal propellers with multilinkage mechanism.

Fast prediction method of propeller hydrodynamic performance based on SPF-LSTM

In order to realize fast and accurate prediction of hydrodynamic performance of UUV propeller, a hydrodynamic performance prediction model based on SPF-LSTM neural network was proposed in this paper, which combined with real propeller flow test and CFD numerical simulation technology. The model comprehensively considered the test data of real paddle and the simulation data based on CFD numerical simulation, and adopted the Sample penalty factor (SPF) to optimize the initial weight of the model, adjust the sensitivity of the model to different samples, and further improve the prediction accuracy. The experimental results show that the prediction results of this model are in good agreement with the test data of real propeller, and the calculation period is very short and the efficiency is high, which meets the requirement of real-time and accurate prediction of the open water performance of propeller.

Computational Analysis of Cavitating Flows around a Marine Propeller Using Incompressible, Isothermal Compressible, and Fully Compressible Flow Solvers

This research investigates cavitation around a marine propeller, employing computational fluid dynamic (CFD) solvers, including an incompressible, isothermal compressible, and fully compressible flow. The investigation commenced with simulations utilizing an incompressible flow solver, subsequently extending to the two compressible flow solvers. In the compressible flow, there is a close interrelation between density, pressure, and temperature, which significantly influences cavitation dynamics. To verify computational methods, verification tests were conducted for leading-edge cavitating flows over a two-dimensional (2D)-modified NACA66 hydrofoil section at various cavitation numbers. The computational results were validated against the experimental data, with the solvers’ capability to predict cavitation forming the basis for comparison. The results demonstrate consistent predictions among the solvers; however, the fully compressible flow solver demonstrated a superior performance in capturing re-entrant jets and accurately modeling cavity closure regions. Furthermore, the fully compressible flow solver precisely estimated propeller hydrodynamic performance, yielding results closely aligned with experimental observations.

Numerical analysis of wake field and unsteady forces on submarine propeller with twisted rudders

A twisted submarine rudder was designed to reduce the unsteady force on and improve the propulsion efficiency of the propeller. The twisted rudder not only switches the wake in the pre-rotation state in the direction opposite to the propeller rotation but also increases the mismatch between the circumferential phase-angle distribution characteristics of the wake peak and propeller profile at each radius. To investigate the influence of this rudder on the submarine's flow field and the propeller's hydrodynamic performance, the shear stress transport (SST) k−ω turbulence model was used to calculate and compare the resistance characteristics and flow field at the aft of the submarine without a propeller when the ordinary and twisted rudders were installed, as well as the wake field of and unsteady force on the propeller with the propeller. The circumferential velocity in the propeller wake was significantly reduced, and the propulsion efficiency was improved by approximately 7.31%. In addition, the pulsation amplitude of the unsteady force was significantly reduced. The main blade-passing frequency (1BPF) amplitudes of the force and torque decreased by more than 40% and 35%, respectively, which significantly reduced the hull vibration caused by the unsteady force on the propeller.

Numerical simulations of water-air-bubble mixed flows around hydrofoil and propeller

Water-air-bubble mixed flow is a complex multiphase flow usually generated due to the intense interaction between the sailing ship and the free surface[1]. A large number of bubbles scour down along the ship which gather around the propulsion system, making a significant effect on the hydrodynamic performance of propeller and hydrofoil. In this paper, the hydrodynamic performance of two-dimensional hydrofoil and three-dimensional propeller in uniformly mixed water-air-bubble incoming flow is studied by using the Computational Fluid Dynamics (CFD) method. Euler-Euler two-fluid model is used to simulate the uniformly mixed water-air-bubble incoming flow with the open-source CFD software OpenFOAM. The feasibility of numerical simulation is verified by comparing the numerical simulation results with experimental data. On this basis, the changes of physical fields around two-dimensional hydrofoil and three-dimensional propeller caused by water-air-bubble flow under multiple air fraction conditions are discussed. In addition, the differences in dimensionless coefficients are compared between single-phase flow conditions and two-phase flow. Furthermore, the Population Balance Model (PBM) is used in the simulation of two-dimensional hydrofoil to observe the coalescence and break of bubbles.

Numerical Simulation of Hydrodynamic Performance of Podded Propulsion under Maneuvering Condition

Podded propulsion offers excellent maneuverability without the need for mechanically complex transmission systems. However, the hydrodynamic performance of podded propulsion under maneuvering conditions has not yet been adequately investigated. This study proposes a Reynolds-averaged Navier–Stokes (RANS)-based method to investigate the hydrodynamic performance of pod thrusters under maneuvering conditions. The accuracy of the numerical method is verified based on a comprehensive convergence analysis and experimental comparison. A comparative analysis of the difference in thrust, moment and their coefficients between maneuvering and steady-state conditions is performed. Additionally, the impact of the advance number on the propeller hydrodynamic performance under maneuvering conditions is examined. The results demonstrate that the thrust coefficient and the torque coefficient of the propeller at positive and negative oblique flow angles exhibit asymmetry owing to the influence of the incoming flow velocity. Furthermore, the thrust and torque under maneuvering conditions increase significantly compared with those under the steady-state condition.

Marine propeller underwater radiated noise prediction with the FWH acoustic analogy Part 1: Assessment of model scale propeller hydroacoustic performance under uniform and inclined flow conditions

This paper explores hydrodynamic performance, including cavitation and URN for the benchmark model scale propeller, The Princess Royal, operating under uniform and inclined flow conditions. In the numerical calculations, the DES method and the k-ω SST turbulence model were utilised to solve the cavitating flow around the propeller and determine the source field for the sound propagation. Also, the developed V-AMR advanced meshing technique was applied for accurately solving the tip vortex flow and hence better representation of the tip vortex cavitation in the propeller slipstream. The Schnerr-Sauer mass transfer model was used to model the cavitation on and off the propeller blades, whereas the cavitating propeller URN was predicted using the permeable formulation of the FWH equation. The numerical results were first validated with the available experimental data in model scale in a wide range of operating conditions through the propeller hydrodynamic performance characteristics, cavitation extensions and URN. Then, the numerical URN predictions were extrapolated to full-scale with the aid of the ITTC procedure to compare the CFD predictions with the extrapolated measured data obtained by different testing facilities within the scope of a recently conducted international round-robin test campaign. The results showed that the sheet and tip vortex cavitation was generally modelled successfully in the numerical calculations compared to the model-scale experimental observations in different facilities. The propeller URN predictions were in good agreement with the measured data in model scale, although some URN level discrepancies (i.e., around 5 and 10 dB) were observed between numerical predictions and model-scale measurements at certain frequencies in the low-frequency region of the noise spectrum. By taking the URN level differences measured in each facility into account, the full-scale extrapolated propeller URN predictions satisfactorily agree with the extrapolated full-scale experimental test data. Therefore, this study confirms that the CFD methods, together with the acoustic analogy, can be used for predicting the propeller URN, similar to other traditional ship hydrodynamic phenomena (e.g., resistance, self-propulsion, cavitation etc.).

Marine propeller underwater radiated noise prediction with the FWH acoustic analogy Part 2: Assessment of model scale propeller hydroacoustic performance under non-uniform flow conditions

This study presents the model scale benchmark, The Princess Royal, propeller's hydrodynamic performance, including cavitation extensions and URN operating in a non-uniform wake field. The developed V-AMR technique was used in the numerical calculations to accurately solve the tip vortex flow and better representation the tip vortex cavitation (TVC) in the propeller slipstream. The sheet and tip vortex cavitation was modelled using the Schnerr-Sauer cavitation model. A hybrid method, combining the DES and permeable formulation of the FWH equation, was used for predicting the propeller URN at four different operating conditions corresponding to full-scale operating conditions. The numerical results were first validated with the experimental data obtained in the cavitation tunnel through the propeller hydrodynamic characteristics, cavitation extension and URN in model scale. Then, the propeller URN predictions using a hybrid method were extrapolated to full-scale with the ITTC extrapolation procedure to compare the numerical results with the extrapolated experimental data and full-scale measurements. The results showed that the cavitation extensions on and off the blades were satisfactorily predicted in the numerical calculations compared to the model-scale campaigns and full-scale sea trial observations. However, the same cavitation dynamics and TVC could not be predicted in conditions where the weak and incipient TVC were present between the numerical calculations and model-scale test campaign. Also, the numerical calculations underpredicted the model scale propeller URN at certain frequencies compared to model scale experimental data, except for the highest loading condition. Akin to the comparisons of model scale propeller URN between the numerical calculations and model-scale test data, the extrapolated propeller URN was generally underpredicted at a certain frequency range of the noise spectrum in the numerical calculations compared to the full-scale measurements. This underprediction in the numerical calculations can be associated with the lack of cavitation dynamics, especially TVC, compared to experimental and full-scale observations.

Numerical investigation into the effects of tip vortex cavitation on propeller underwater radiated noise (URN) using a hybrid CFD method

This study explores the influence of tip vortex cavitation (TVC) on propeller induced URN using a hybrid CFD method. The cavitating flow around the model and full-scale benchmark propeller belong to the Newcastle University's research vessel, The Princess Royal, operating under uniform, inclined and non-uniform flow conditions were solved using DES and mass transfer model. The recently developed advanced mesh refinement (V-AMR) technique was incorporated into the calculations for better modelling tip vortex flow and realising the TVC in the propeller slipstream. This technique enabled the inclusion of the nonlinear noise sources, mainly represented by turbulence and vorticity, including TVC, effectively for the accurate prediction of propeller URN. The numerical calculations were conducted in conditions where only the sheet cavitation was modelled without the V-AMR technique and where the sheet and tip vortex cavitation was modelled together using the V-AMR technique to understand the contribution of TVC to the overall propeller URN. The results were first validated with the available experimental data obtained in the model scale test campaign in the cavitation tunnel and sea-trial data for the propeller's hydrodynamic performance characteristics, cavitation extensions and URN. The results showed that the contribution of TVC to the overall propeller URN was minimal in conditions where the stable and structured TVC was present (i.e., under uniform flow conditions). However, when the propeller was operating under inclined and non-uniform flow conditions where the cavitation dynamics and vortex pulsation were dominant, the unstructured and unstable TVC was observed compared to the observations of TVC under uniform flow conditions. The unstructured TVC created several spikes, which can be associated with its strong cavitation dynamics and possible collapsing/bursting phenomena. These spikes created by the TVC and observed in the time domain acoustic pressure signal consequently contributed to the propeller URN at the different frequency ranges of the noise spectrum and increased the URN levels up to 15 dB under non-uniform flow conditions compared to the propeller URN predictions when only the sheet cavitation was present.

Mitigation of Hub Vortex Cavitation with Application of Roughness

This study investigates the influence of roughness on hydrodynamic performance, especially for the hub vortex—and, hence, hub vortex cavitation—of a benchmark propeller operating under uniform flow conditions using the RANS method. The Schnerr–Sauer cavitation model is also used for modelling the cavitation on and off the propeller blades. In order to include the effects of roughness in the numerical calculations, the experimentally obtained roughness functions were incorporated with the wall function of the CFD solver. The applicability and effectiveness of the roughness application applied on the propeller hub as a novel concept were explored to mitigate hub vortex cavitation. The results are first validated with experimental data on smooth conditions through the propeller hydrodynamic performance characteristics and cavitation extension. Then, the propeller hub is covered with four different sizes of roughness. The results show that the degradation effects of roughness applied to the hub on propeller performance are negligible, and the maximum efficiency loss is around 0.25% with respect to the smooth condition when the propeller hub was roughened. Favourable impacts of roughness are found for the hub vortex, and hence, hub vortex mitigation. Applying the roughness on the propeller changed the flow properties (e.g., pressure, velocity and turbulent kinetic energy) inside the vortex, enabling the early breakdown of the extension of hub vortices. These flow changes in the presence of roughness result in a mitigation of hub vortex cavitation up to 50% depending on the roughness size with respect to the smooth condition. Thus, this proposed novel concept, application of roughness to the propeller hub, can be used to mitigate hub vortex cavitation, rudder erosion and propeller URN for both newly designed and retrofitted projects by keeping the efficiency loss as minimum as possible.

Influence of lift distribution coefficient on hydrodynamic performance of propeller in forward and astern mode of operation by numerical analysis

Influence of lift distribution coefficient on hydrodynamic performance of propeller in forward and astern mode of operation by numerical analysis

Enhancement of the ship propeller hydrodynamic performance by different energy-saving devices mounted at the upstream zone

Enhancement of the ship propeller hydrodynamic performance by different energy-saving devices mounted at the upstream zone

The effect of time discretization on the propeller hydrodynamic performance simulation in self-propulsion and open water conditions

Numerical simulation technology is widely used in the field of naval architect and marine engineering. The flow induced by the propeller is unsteady. In order to demonstrate the effect of time discretization format and time step on the simulation of the flow, this paper takes an oil tanker and its propeller as the research objects, and simulations have been conducted by using OpenFoam. By comparing the thrust, torque and the vortex after the propeller, the effects of the time discretization format and time step on the numerical simulations are analyzed. This paper believes that changing the discretization format of the time term while keep the time step unchanged has little effect on the calculation results in the condition of open water test simulation. It is beneficial to simulate of the vortex after the propeller hub by using a small time step. The first-order backward Euler discretization format in the condition of self propulsion simulation is recommended. If the error of thrust compared with experiment data is larger than expected, the second-order discretization format should be considered. In order to improve the accuracy of numerical simulation, a smaller time step could be considered.

Analysis of water jet propeller hydrodynamic performance based on CFD

The method of ducted propeller design is used to design the impeller of water jet propeller. The method of space transformation is used to transform the two-dimensional NACA airfoil into three-dimensional airfoil. The flow field model of water jet propeller is generated by structured grid. The SST model is using for calculation and the maximum thrust is 170.4N when the rotation speed is 4000R / min and the inlet velocity is 2m / s.

Influence of Ice Size Parameter Variation on Hydrodynamic Performance of Podded Propulsor

During ice-breaking navigation, a massive amount of crushed ice blocks with different sizes is accumulated under the hull of an ice-going ship. This ice slides into the flow field in the forward side of the podded propulsor, affecting the surrounding flow field and aggravating the non-uniformity of the propeller wake. A pulsating load is formed on the propeller, which affects the hydrodynamic performance of the podded propulsor. To study the changes in the propeller hydrodynamic performance during the ice-podded propulsor interaction, the overlapping grid technique is used to simulate the unsteady hydrodynamic performance of the podded propulsor at different propeller rotation angles and different ice block sizes. Hence, the hydrodynamic blade behavior during propeller rotation under the interaction between the ice and podded propulsor is discussed. The unsteady propeller loads and surrounding flow fields obtained for ice blocks with different sizes interacting with the podded propulsor are analyzed in detail. The variation in the hydrodynamic performance during the circular motion of a propeller and the influence of ice size variation on the propeller thrust and torque are determined. The calculation results have certain reference significance for experiment-based research, theoretical calculations and numerical simulation concerning ice-podded propulsor interaction.

CFD results on hydrodynamic performances of a marine propeller

In this work, the commercial Computational Fluid Dynamics (CFD), ANSYS-Fluent V.14.5 has been used to illustrate the effects of rudder and blade pitch on hydrodynamic performances of a propeller. At first, the characteristic curves of a container ship propeller are computed. Then, effects of rudder on hydrodynamic performances of the propeller in the both cases of the propeller with and without rudder have been investigated. The relationships between the blade pitch angle and the hydrodynamic performances of the selected referent propeller in this work having designed conditions as diameter of 3.65 m; speed of 200 rpm; average pitch of 2.459 m and the boss ratio of 0.1730. Using CFD, the characteristic curves of the marine propeller, pressure distribution, velocity distribution around propeller and the efficiency of the propeller have been shown. From the obtained results, the effects of rudder and blade pitch angle on hydrodynamic performances of the propeller have been evaluated.

Numerical Analysis of Influence of the Hull Couple Motion on the Propeller Exciting Force Characteristics

The numerical calculation was performed for the KRISO Container Ship (KCS) hull-propeller-rudder system with different freedom hull motion by employing the Reynolds-Averaged Navier-Stokes (RANS) method and adopting the overset grid. Firstly, the numerical simulation of hydrodynamics for a bare hull with the heave and pitch motion is carried out. The results show that the space non-uniformity of a nominal wake in the disk plane with motion is comparable to the case without motion. However, the time non-uniformity increases sharply and it has a significant positive relationship with the motion amplitude. Then, the propeller exciting force is calculated in the case including single heave, single pitch and their couple motion. It was found that both the ship and propeller hydrodynamic performance deteriorated dramatically due to the hull motion. Furthermore, the spectrum peak at the motion frequency is dominant in all the peak values and the larger the amplitude is, the higher the motion frequency peak is expected to be. For the propeller bearing force, the effect of the different hull motions appears as linear superimposition. However, the superimposition of different hull motions enlarges the propeller-induced fluctuating pressure in a single motion.

Comparative Analysis of Hydrodynamic Performance of Propeller Under Different Turbulence Models

In order to study the applicability of different turbulence models in the prediction of propeller hydrodynamic performance, computational fluid dynamics software CFX was used to simulate the thrust coefficient, torque coefficient and efficiency of VP1304 propeller under specific viscous flow field conditions by using k - ε models, k - ω models, SST models and RSM models respectively. The prediction results from the four turbulence models are compared with the experimental data of controlled pitch propeller VP1304 published by SVA Potsdam. It is concluded that the simulation prediction of performance due to the RSM model is the most accurate, Merits and demerits of RSM model is analyzed.