Propeller Model Research Articles

Dynamic manoeuvres of KCS in waves using URANS computations with overset grids

This paper presents a CFD URANS approach to model self-propelled free running maneouvres for autonomous or remote-controlled surface vessels in calm water and Stokes waves. The object of study in this paper is a benchmark container ship KCS. A hierarchy of overset grids are utilised, allowing active rudder motions while the vessel is undertaking 6 DoF turning circle and zig-zag manoeuvres. Body force propeller model (BFM) is adopted to drive the vessel at a constant approaching speed corresponds to Fr=0.26. Verification and validation study is performed for estimating the numerical uncertainties within the computations. In calm water, the computed vessel trajectories and velocities are compared against experimental data from literature and mathematical model (MM) based simulation results. Differences between URANS and experimental data are around 10.0%. After introducing waves, the manoeuvring behaviour of the vessel changes due to the presence of wave frequency loads and drift loads. The wave frequency loads exert fluctuations on measurements such as velocity, yaw rate, vessel encounted loads and etc., while the drift loads result in shift in the vessel’s trajectory especially for the turning circle manoeuvre.

Метод пересчета на натурные условия уровней кавитационного шума моделей гребных винтов при измерении в однородном потоке

Метод пересчета на натурные условия уровней кавитационного шума моделей гребных винтов при измерении в однородном потоке

Aerodynamic model of propeller–wing interaction for distributed propeller aircraft concept

The present investigation addresses two key issues in aerodynamic performance of a propeller–wing configuration, namely linear and nonlinear predictions with low-order numerical models. The developed aerodynamic model is targeted to be used in the preliminary aircraft design loop. First, the combination of selected propeller model, i.e. blade element theory with the wing model, i.e. lifting line theory and vortex lattice method is considered for linear aerodynamic model. Second, for the nonlinear prediction, a modified vortex lattice method is paired with the two-dimensional viscous effect of the airfoils to simplify and reduce the computational time. These models are implemented and validated with existing experimental data to predict the differences in lift and drag distribution. Overall, the predicted results show agreement with low percentage of error compared with the experimental data for various thrust coefficients and produced induced drag distribution that behaves as expected.

A CFD study on the correlation between the skew angle and blade number of hydrodynamic performance of a submarine propeller

In the present study, the correlation between skew angle and blade number on the hydrodynamic performance of a submarine propeller is numerically investigated using computational fluid dynamics. For this purpose, three different blade numbers (3, 5 and 7 blades) and four different skew angles which vary from 0° to 52° are considered based on the INSEAN E1619 propeller model as the main geometry. Three-dimensional numerical simulation is based on Unsteady Reynolds-Averaged Navier–Stokes equations combined with SST k–ω turbulence model. The hydrodynamic coefficients and efficiency are compared against the experimental and numerical results at various advance coefficients (J), and good agreement is achieved. Based on the results, by increasing the blade number, hydrodynamic coefficients are improved. The interaction between 7 blades dissipates the negative wake region in locations near the propeller blades which leads to produce higher hydrodynamic efficiency compared to other propellers. The maximum torque coefficient is generated by the propeller with 7 blades which is enhanced by about 11.8% compared to the propeller with 3 blades at J = 0.88. In addition, lower skew angle gives slightly higher performance than the high skew angle propeller. In overall, hydrodynamic efficiency of the propeller with a skew angle equal to 0° is enhanced by about 19.4% compared to the propeller with skew angles equal to 52° at J = 0.88.

Real-time integrated turboprop take-off model under propeller-wing interaction

PurposeThe purpose of the paper is to build a real-time integrated turboprop take-off model which fully takes the interaction between diverse parts of aircraft into consideration. Turboprops have the advantage of short take-off distance derived from propeller-wing interaction. Traditional turboprop take-off model is inappropriate because interactions between diverse parts of aircrafts are not fully considered or longer calculation time is required. To make full use of the advantage of short take-off distance, a real-time integrated take-off model is needed for analysing flight performance and developing an integrated propeller-engine-aircraft control system.Design/methodology/approachA new integrated three-degree-of-freedom take-off model is developed, which takes a modified propeller model, a wing model and the predominant propeller-wing interaction into account. The propeller model, based on strip theory, overcomes the shortage that the strip theory does not work if the angle of propeller axis and inflow velocity is non-zero. The wing model uses the lifting line method. The proposed propeller-wing interaction model simplifies the complex propeller-wing flow field. Simulations of ATR42 take-off model are conducted in the following three modes: propeller-wing interaction is ignored; influence of propeller on wing is considered only; and propeller-wing interaction is considered.FindingsComparison of take-off distances and flight parameters shows that propeller-wing interaction has a vital impact on take-off distance and flight parameters of turboprops.Practical implicationsThe real-time integrated take-off model provides time-history flight parameters, which plays an important role in an integrated propeller-engine-aircraft control system to analyse and improve flight performance.Originality/valueThe real-time integrated take-off model is more precise because propeller-wing interaction is considered. Each calculation step costs less than 20 ms, which meets real-time calculation requirements. The modified propeller model overcomes the shortage of strip theory.

Simulation of solid propellant microstructures by combining the collective rearrangement method with the discrete element method

The polydisperse particulate components in solid propellant are incompact and randomly packed, which determines the microstructural features of the propellants. A packing method, combining the discrete element method (DEM) and collective rearrangement method, was applied to model propellant microstructures. The validity of this method was investigated by comparing the calculated and experimental properties of the monodisperse, bidisperse, and polydisperse random close packed sphere systems. The propellant models were generated using a stepwise approach, and their homogeneity, local randomness, and long-range pattern were analyzed. A statistical study of aluminum (Al) particle distribution was also conducted. The results indicated that this packing method can effectively determine the microscopic characteristics of random close packed monodisperse spheres. The maximum packing fraction of bidisperse and polydisperse spheres had similar trends to those reported in experimental studies and using other packing algorithms. In addition, this method was capable of generating non-compacted propellant structures with uniformly distributed polydisperse particles. The radial distribution functions (RDFs) for Al-Al particles provided information about the Al distribution, but this was mainly related to the size and content of the large particle components.

Scour Induced by Single and Twin Propeller Jets

Single and twin ship propeller jets produce scour holes with deposition dune. The scour hole has a maximum depth at a particular length downstream within the propeller jet. Existing equations are available to predict maximum scour depth and the corresponding scour length downstream. Experiments conducted with various physical propeller models, rotational speeds, propeller-to-propeller distances and bed clearances are presented. The measurements allowed a better understanding of the mechanism of temporal scour and deposition formation for scour caused by single-propeller and twin-propeller. Results show that the propeller jet scour profiles can be divided into three zones, which are the small scour hole, primary scour hole and deposition dune. An empirical 2D scour model is proposed to predict the scour profile for both a single-propeller and twin-propeller using a Gaussian normal distribution.

Comparisons of MHD propeller model with observations of cataclysmic variable AE Aqr

ABSTRACT We have developed a numerical magnetohydrodynamic (MHD) model of the propeller candidate star AE Aqr using axisymmetric MHD simulations. We suggest that AE Aqr is an intermediate polar-type star, where the magnetic field is relatively weak and an accretion disc may form around the white dwarf. The star is in the propeller regime, and many of its observational properties are determined by the disc–magnetosphere interaction. Comparisons of the characteristics of the observed versus modelled AE Aqr star show that the model can explain many observational properties of AE Aqr. In a representative model, the magnetic field of the star is B ≈ 3.3 × 105 G and the time-averaged accretion rate in the disc is 5.5 × 1016 g s−1. Most of this matter is ejected into conically shaped winds. The numerical model explains the rapid spin-down of AE Aqr through the outflow of angular momentum from the surface of the star to the wind, corona, and disc. The energy budget in the outflows, 9 × 1033 erg s−1, is sufficient for explaining the observed flaring radiation in different wavebands. The time-scale of ejections into the wind matches the short time-scale variability in the light curves of AE Aqr.

Unsteady Detached-Eddy Simulation (DES) of the Jetstream 31 aircraft in One Engine Inoperative (OEI) condition with propeller modelling

Numerical results from a three-dimensional (3D) computational fluid dynamics (CFD) model of the Jetstream 31 aircraft in conditions of one engine inoperative are presented. The objective of this work is to analyse the performance of the Jetstream 31 aircraft and provide transient data using an unsteady Detached-Eddy Simulation (DES) CFD approach and a numerical propeller model to compare computational results with a single engine flight test experiment. The propeller modelling approach has been implemented through User-Defined Functions using C programming language to replicate the propeller effect. Different angles of attack and sideslip are studied, based on records from flight test data, both with unsteady (DES) and steady-state Reynolds-Averaged Navier-Stokes (RANS) models. An error analysis on the flight test data provides an error band from 2% to 16% among all cases, high values due to the lack of many data samples. Across the RANS approach, an average deviation of 6.9% and 3.8% for respectively lift and drag coefficients is achieved. By applying the DES turbulence modelling approach, a better lift prediction is achieved (5.4%) despite a slightly worse drag (4.5%). It has also been found that 80% of the numerical results are within the error band defined. A close agreement has been found within moment coefficients, with average percentage deviations from 3.3% to 7.0%. Overall, an analysis has been carried out in the present work, both on the flight test and computational sides to provide reliable numerical results of these aerodynamic properties.

DTMB 5415M dynamic manoeuvres with URANS computation using body-force and discretised propeller models

This paper presents model scale computations of self-propelled turning circle and zig-zag manoeuvres for a benchmark combatant DTMB 5415M adopting the unsteady Reynolds-Averaged Navier-Stokes (URANS) equations. A hierarchy of overset grids is utilised to allow rudder deflections while the ship undertakes 6 DOF dynamic motions. With both manoeuvres executed at approach speed corresponds to Fr = 0.41, two different propulsion techniques are applied to drive the free running vessel; the body force propeller model (BFM) and the discretised propeller model (DPM). A verification and validation study is also performed for estimating the numerical uncertainties within the URANS simulated manoeuvres. Comparisons of the results are made between computations adopting the two propulsion approaches and against experimental data from literature. The BFM propulsion method in this study is shown to under-predict the magnitude of propeller induced wake passing the rudders compared to the DPM approach which is able to resolve high fidelity flow physics behind the propellers. In general, the comparison between experimental and numerical results agree mostly within about 10% for the studied turning circle and zig-zag manoeuvres.

Numerical Study of Fillet Surface Effect on the Ducted Performance Using OpenFOAM

In the present study, the effect of fillet surface on the performance of the ducted propeller using Reynolds-Average Navier Stokes (RANS) method is applied. The numerical simulations compare the propeller model with fillet on the surface and without fillet. OpenFOAM is used to simulate the performances and solve the problems in the open water propeller simulation. MRF approach is applied for this simulation. Kaplan model with the 19A nozzle is investigated by comparing the results with experimental data. The effect of fillet surface on the ducted propeller are presented and discussed in this study.

Correlation study between propeller noise and cavitation erosion with inclined propeller model test

Correlation study between propeller noise and cavitation erosion with inclined propeller model test

Numerical Estimation of Glass Fiber Reinforced Plastic Propeller Performance Using Rigid and Flexible Model

Composite materials have offered some improvements on the performance of hydrodynamic and structures of marine constructions. The high strength to weight and stiffness to weight ratio might be tailored through the exploitation of the fiber orientation in order to reduce the load and the stress distribution of the structure. In order to fully explore the performance of the developed glass fiber reinforce plastics (GFRP) B-series propeller for traditional purse seine boat in the North Coast of Central Java, the aim of the research is focused on the comparison of the rigid and the flexible model adopted for the simulation analysis of the propeller performance. The thrust force, the torque moment and the efficiency of the two propeller models are discussed.

A semi-empirical multi-degree of freedom body force propeller model

Efficient and accurate modelling of a self-propelled vessel in a large amplitude seaway with CFD-based numerical methods is a challenging task and is prohibitively expensive for most designers and engineers. Viscous CFD methods can accurately model viscous effects, but the small numerical time step required to analyze the rotating propeller leads to a large computational cost. A method for efficiently and accurately modelling the six degree of freedom force on the propeller is required to feasibly model a self propelled vessel maneuvering in a high amplitude seaway. This paper outlines the framework for developing an unsteady body force propeller model for unsteady conditions. The purpose of this study is to train a semi-empirical algorithm to accurately prescribe the unsteady body force to model the propeller. The MOERI Container ship propeller is analyzed with RANS CFD. Open water data is compared to the RANS CFD results of a steady Moving Reference Frame approach. Unsteady surge and propeller revolution rate are applied to a transient rotating mesh model in open water and behind condition. The predictions of the algorithm match well with the CFD results.

Propeller modeling approaches for off–design operative conditions

In adverse situations, such as maneuvering and motion in waves, severe variations of the propeller inflow may be experienced, resulting in an increase of propeller thrust and torque and in the generation of in-plane loads. This may cause undesired hull-vibratory loads, stress of the propulsive system and even affect somehow the ship dynamic response. Thus, a reliable prediction of these phenomena during design phases is necessary to comply with the increasingly stringent constraints on safety at sea, propulsive efficiency, vibration and noise pollution. In the present work, the capabilities of a propeller solver based on a potential, boundary element method, routinely used in the optimization process of the propulsive device, to analyze the propeller performance under different maneuvering conditions are considered. After a first validation against uRANS simulations considering a simple oblique flow, the analysis is broadened to a propeller operating in the wake field of a twin screw ship in different maneuvering conditions, for which experimental results from free running tests in model scale are available. The BEM solver is compared also to a steady blade element approach in order to achieve an overview of the respective pros and cons in view of their inclusion in CFD simulations.

The Analysis of Overall Ship Fuel Consumption in Acceleration Manoeuvre Using Hull-Propeller-Engine Interaction Principles and Governor Features

Abstract The problem of reduction of greenhouse gas emissions in shipping is currently addressed by many research works and related industries. There are many existing and visionary technologies and ideas, which are conceptually defined or practically realised. This goal can be achieved in different ways, and reducing fuel consumption is one of the major methods. In these circumstances, the aim of this study is to analyse the possibility of fuel consumption reduction by using an alternative control strategy for low-speed marine diesel engines which would take into account the interactions between hull, propeller and main engine. For this purpose, a mathematical model including ship hull and propulsion system is developed. A case study is conducted for a ship for which the results of both the ship hull and screw propeller model tests are available. A low-speed two-stroke diesel engine is then selected for the considered ship. Two different governors are included in the model and their parameters are changed to investigate the dynamic behaviour of the system when simulating the forward acceleration mode in calm sea conditions. The research is mainly focused on variations of fuel consumption by the ship passing a certain distance to reach the nominal constant speed. It is concluded that, for a given travel distance, it is possible to save considerable amount of fuel at the expense of slight increase of journey time.

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

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.

Screen Compliance Experiments for Application of Liquid Acquisition Device in Space

The purpose of a liquid acquisition device (LAD) is to separate liquid and vapor phases inside a spacecraft propellant storage tank in the reduced gravity and microgravity conditions of space so that vapor-free liquid can be extracted to the transfer line. A popular type of LAD called a screen channel LAD or gallery arm, uses a fine porous screen and surface tension forces of the liquid to allow pure liquid to flow through the screen while blocking vapor penetration. To analyze, size, and optimize the design of LADs for future in-space propellant transfer systems, models and data are required for the four fundamental influential factors for LAD systems, including bubble point, flow-through-screen pressure drop, wicking rate, and screen compliance for a wide variety of screen meshes. While there is sporadic data available for three of these parameters, there is no published quantitative data for screen compliance. During the transient startup of propellant transfer, the liquid must be accelerated from rest to the steady flow demand velocity, which causes the screen to deform or comply, so compliance data is required for accurate transient LAD analyses; most design codes only consider steady state analysis. This paper presents screen compliance experiments on 14 different screens, examining the effects of fineness of mesh, open area, and screen metal type on compliance. A basic equation of state is also developed and validated against the data which can be easily integrated into any transient LAD flow code to model propellant transfer.

Tuning of ADRC for QTR in Transition Process Based on NBPO Hybrid Algorithm

The quad tilt rotor (QTR) has complex dynamics characteristics, and the environmental factors have a great influence on it. This increases the difficulty of its control especially in transition mode. To solve this problem, the design of the controller based on active disturbance rejection control (ADRC) with a novel tuning algorithm is proposed in this paper. The aerodynamic models of propeller, wing, vertical tail and fuselage are build respectively by using the idea of component modeling. The pitch channel of the linearized flight dynamic model is provided for the control system. A simple tuning method of active disturbance rejection control for the quad tilt rotor in transition process that achieves high performance and good robustness is presented. The proposed method makes ADRC become easy to tune and more practical. The problem of parameter tuning is turned into a multi-objective optimization problem, and using radial basis function(RBF) neural network with particle swarm optimization algorithm(PSO) and bacterial foraging optimization algorithm(BFO) hybrid algorithm tuning method(NBPO) to fit the tuning rules. We introduce the control input, the overshoot and rise time of the system into the fitness function. The local and global optimal solutions are introduced into the chemotaxis and migration to improve the information exchange ability of BFO. The correctness and effectiveness of the NBPO tuning method were verified by numerical simulation results, compared with the one parameter tuning method(OPM) and PID, the results showed that the NBPO tuning method can greatly improve the control performance of the system.

Numerical Prediction of Wall Effect on Propeller in Restricted Channel

In restricted channel, the hydrodynamic performance of propeller is affected by the wall. In the present work, two cylindrical channels with different diameters being 1.8D and 5.0D are adopted to study the influence of wall on the hydrodynamic performance and wake field of the propeller model DTMB4119. The numerical simulations are carried out by the single-phase solver pimpleDyMFoam in open source platform OpenFOAM. The Reynolds Averaged Navier-Stokes equations (RANS) are adopted to solve the flow field. The arbitrary mesh interface (AMI) method is used to simulate the rotation of propeller. The designed advance ratio, J = 0.833, is applied in all the computations. For the 5.0 D case, the predicted results of open water performance are in good agreement with experiment data. In restricted channel, the predicted results of thrust and torque coefficients are larger than the open water case. The pressure on the wall of restricted channel downstream increases and approaches the results in open water gradually. Due to the flux conservation, higher negative induced velocity is investigated in the flow field of the propeller in restricted channel.