Propeller Interaction Research Articles

The design and energy saving effect prediction of rudder-bulb-fin device based on CFD and model test

Recent developments in Computational Fluid Dynamics (CFD) and high-performance computer hardware have made it possible to design Energy Saving Devices (ESDs) using numerical methods. The present work investigates the influence of rudder bulb diameter, thrust fin; span, chord length and angle of attack on propulsive efficiency. In order to increase computational efficiency, a hypothesis was developed and a quick estimate method for design parameters and the optimization procedure. Bare hull resistance, propeller open water performance and interaction of hull-propeller-rudder simulations were carried out using CFD code to solve Reynolds Averaged Navier-Stokes (RANS) equations. A validation study shows a good agreement between the CFD and experimental data. Model tests were carried out using optimum parameters for rudder bulb and rudder attached thrust fins. Comparison of the propulsive efficiency between the ship with the conventional rudder and ship with the optimized rudder-bulb-fin device was done. The model test predicted energy gains of 2.18% compared to 2.63% gains predicted by the CFD method. This study would be useful during design and optimization of rudder-bulb-fin.

A comprehensive mathematical model and the methodology for assessing technical excellence road trains with active links and all-wheel control

This article presents the main provisions of the new scientific and methodological approach, integrated mathematical model and methodics assessing the technical perfection of wheeled transport means of particularly large capacity based on road trains with active links and all wheeled steering. The results of the research allowed us to justify scientific and methodological approach to the assessment of technical excellence wheeled transport means of particularly large capacity based on road trains with active links and all wheeled steering, which includes implemented conceptual apparatus, scientific concepts and principles, theoretical and practical provisions. Results of justification and developing integrated mathematical model include the total mass equations, and methodics wheeled transport means of particularly large capacity based on road trains with active links and all wheeled steering. Introduced the concept of the integrated mathematical model, justified and developed by the integrated mathematical model wheeled transport means of particularly large capacity based on road trains with active links and all wheeled steering, in which includes the equation of the total mass of transport means in absolute and relative values, equations of dynamics of sprung and unsprung masses of links of wheeled transport means, equations of joint dynamics of wheeled transport means taking into account the applications of the saddle device and all-wheel control, models of interaction of wheel propellers with the support surface, models of the micro-profile and macro-profile of the support surface, and other component parts united comprehensive model. On the basis comprehensive mathematical model proposed metodics assessment of the technical excellence of the road train with active links and all-wheel control, recommendations on the choice of indicators and evaluation criteria are justified.

A Generalized Hybrid RANSE/BEM Approach for the Analysis of Hull–Propeller Interaction in Off-Design Conditions

During maneuvers, propellers’ operation differs from their design due to strong modification of the wake field with respect to the straight-ahead motion. The consequent modification of the loads overstresses the mechanical components of the shaftline, exacerbates propeller side effects and worsens overall efficiency. Therefore, the analysis of these situations in the early design phase is pivotal to increase the operation capabilities and safety at sea. This task relies on novel tools capable to accurately predict the complex flow field that develops past the hull and the propeller loads. Since the solution of the fully coupled problem with the rotating propeller by viscous flow solver is impractical for routine applications, hybrid approaches are a viable alternative. In this paper, an interactive RANSE/BEM methodology is presented, where the propeller is replaced by rotating body forces that map the actual loading state of the blades, allowing a fully unsteady analysis of hull–propeller interaction. The methodology is applied to the straight ahead and 8.4° pure drift motions of a twin screw propulsive configuration. Last, but not least, the study presents a validation study with accurate experimental data of the nominal wake field and single blade loads.

Aerodynamic Interaction Effects Between Propellers in Typical eVTOL Vehicle Configurations

Many electric vertical takeoff and landing concepts are characterized by nontraditional vehicle layouts with distributed propellers. Two propeller interaction types were distinguished in this Paper, which investigates how propeller interaction in side-by-side and one-after-another configuration affects performance, in terms of thrust, power, in-plane forces, and out-of-plane moments, and how those performance effects depend on axial and lateral propeller spacing. A wind-tunnel experiment was performed with two propeller units, one instrumented with a force/torque sensor and the other introducing the aerodynamic interaction. Total pressure and planar particle-image velocimetry measurements were taken to investigate slipstream characteristics. A strong dependency of interaction effects on the geometric layout was found. For side-by-side interaction characteristic of vertical takeoff and transition, interaction effects varied from weak at small angle of attack to strong at larger angles. A drop in rear propeller thrust of up to 30% was found at constant advance ratio. Keeping thrust constant resulted in power penalties up to 13% for the two propellers combined. For one-after-another interaction, characteristic of cruise, a maximum reduction of thrust of up to 80% was observed. Thrust compensation led to power penalties up to 30% for the rear propeller alone. An extended blade element momentum model captured most interaction effects with sufficient accuracy.

Optimum Propeller Interaction Analysis of Harbourtug With Azimuth Thruster

Determine the safety of tug operation at sea, especially in narrow shipping areas such as port areas, it is necessary to pay attention to the maneuverability of ships and the performance of the ship’s steering system. In ship maneuvering, a specially designed thruster with 360 degrees side thrust with a small turning angle is needed in order to produce a good ship movement performance. In this study, the authors designed a tugboat propeller ka-series four blades. The propeller can move 360 degrees so that the distribution of power is evenly distributed in all directions. The system is expected to provide extra thrust when needed in the process of maneuvering and docking the ship. Equipped with hydraulics used to quickly lift and lower the thruster and pull it back into the hull when not in use. The analysis results show that each propeller variation such as the difference in thrust value, torque value and resulting efficiency. From the analysis model, the highest thrust value was obtained in the first propeller model with a variation of P/D 1, AE/A0 0.45 valued at 306201.4. The lowest torque value is generated in the third propeller model with a variation of P/D 0.6, AE/A0 0.65 value at - 22400.2 Nm. Harbourtug requires a high thrust value, so it is advisable to use the first Propeller model with variations of P/D 1, AE/A0 0.45 The highest efficiency value is obtained in the first propeller model valued at 0.7151.

Numerical Analysis of the Rudder–Propeller Interaction

The proper evaluation of the Rudder–Propeller interactions is mandatory to correctly predict the manoeuvring capability of a modern ship, in particular considering the commonly adopted ship layout (rudder often works in the propeller slipstream). Modern Computational Fluid Dynamics (CFD) solvers can provide, not only the performance of the whole system but also an insight into the flow problem. In the present paper, an open-source viscous flow solver has been validated against available literature experimental measurements in different conditions. After an extensive analysis of the numerical influence of the mesh arrangement and the turbulent quantities on the rudder provided forces, the study focused its attention on the forces generated by the rudder varying the propeller loading conditions and the mutual position between the two devices. These analyses give a hint to describe and improve a commonly-used semi-empirical method based on the actuator disk theory. These analyses also demonstrate the ability of these numerical approaches to correctly predict the interaction behaviour in pre-stall conditions with quite reasonable computational requests (proper also for a design stage), giving additional information on the sectional forces distribution along the span-wise rudder direction, useful to further develop a new semi-empirical rudder model.

Energy-saving optimization for spacing configurations of a pair of self-propelled AUV based on hull form uncertainty design

This paper presents a spacing configuration-based energy-saving optimization approach for a pair of AUVs to achieve minimum resistance through the hull forms and propeller interactions. The traveling resistance is relevant to hull lines optimization design, which uncertainties exist in design variables need to be considered seriously. A reliability analysis based on the first-order reliability method demonstrates that the engineering quality is not acceptable; thus, the design for six sigma was performed with uncertainty optimization to improve the design levels. Two body force models, RANS-UT and RANS-HO, were used to represent the propeller as an axial and a tangential momentum source term. The results highlight that the radial thrust distribution has a significant impact of the propeller performance. For a pair of AUVs, the energy consumption of the fleet is classified into six zones depending on the spacing configurations with a longitudinal offset and transverse separation. This study details and categorizes the relevant sources of the drag reduction and provides the most effective fleet configuration for the optimal energy profits to validate previous experimental results. Based on energy considerations, the optimal fleet configuration is determined to show excellent adaptability and reliability to provide insights for decision makers.

Hull–propeller interaction for planing boats: a numerical study

ABSTRACT Numerical simulations are performed to study the interaction between propeller and hull for two planing vessels: a hard-chine and a tunnelled craft. The numerical model used for reproduction of the problem is validated by comparing the obtained results against published data, showing that a morphing technique is more reliable compared to an overset one. It is demonstrated that propellers strongly affect the performance of a vessel by increasing trim angle and decreasing resistance, which are caused by a noticeable pressure reduction occurring near propellers. These changes are more significant for the case of a tunnelled hull since hydrodynamic pressure acting on the bottom of this vessel is larger compared to a hard-chine craft. While resistance of hulls is seen to be influenced by variation in the position of the propellers at early-planing mode, trim angle is seen to be insensitive to the position of propellers at all speeds.

An investigation of the aerodynamic performance for a propeller-aided lift-enhancing double wing configuration

A propeller-aided lift-enhancing double wing configuration is proposed and investigated in this paper for the purpose of making good use of favorable propeller interferences to promote the aerodynamic performance of the wing. A panel/viscous vortex particle hybrid method is developed to rapidly predict aerodynamic forces. Reynolds averaged Navier-Stokes (RANS) numerical simulations using a multi reference frame method are performed to accurately analyse the complex flow characteristics. It is shown that the proposed configuration has an ability of using a suction action upstream of the propeller and an acceleration effect behind the propeller simultaneously to improve the wing performance. With a single propeller interaction, the lift of the wing is increased by 2.33% and the drag is reduced by 4.64% compared to a clean wing.

Analysis of hull, propeller and engine interactions in regular waves by a combination of experiment and simulation

The goal of this study is to investigate ship propulsion system dynamics under sea wave conditions by including the interaction of hull, propeller, and engine. A mathematical ship propulsion system model was made and the related computer code was developed. To get the results as close as possible to real conditions, measured data for physical models, including the ship’s resistance in calm and sea waves and propeller performance, were implemented in the model. For a diesel engine, performances provided by the manufacturer were used. The wave force time series, as exciting force, changed the propulsion system state from steady to transient. It activated system variables including ship’s speed, advance number, propeller and engine torque, propeller and engine rotational speeds, effective and generated powers, and net thrust. The analysis was performed for a container ship for two regular waves. Using the developed computer code, the ship’s speed and system variables, as well as the consumed fuel and the voyage distance, were calculated and compared with the calm water condition. The voyage mode was set on constant rotational engine speed implementing a P-action governor with fuel rate and engine torque limiters. The outcomes of the research explain the influence of the governor and its limiters on fuel consumption, identify the nonlinear impact of sea waves on propeller characteristics, and underline the effect of voyage mode on system response and the consumed fuel. The results also show that the conventional method for calculating speed reduction based on the added resistance is not capable of justifying the system’s dynamic behaviour.

Numerical Characterisation of the Aeroacoustic Signature of Propeller Arrays for Distributed Electric Propulsion

This paper presents an investigation of the aerodynamic and aeroacoustic interaction of propellers for distributed electric propulsion applications. The rationale underlying the research is related to the key role that aeroacoustics plays in the establishment of the future commercial aviation scenario. The sustainable development of airborne transportation system is currently constrained by community noise, which limits the operations of existing airports and prevents the building of new ones. In addition, the substantial saturation of the existing noise abatement technologies inhibits the further development of the existing fleet, and imposes the adoption of disruptive configurations in terms of airframe layout and propulsion technology. Simulation-based data may help in clarifying many aspects related to the acoustic impact of such innovative concepts. Blended-wing-body equipped with distributed electric propulsion is one of the most promising, due to the beneficial effect of the substantial shielding induced by its geometry. Nevertheless, the novelty of the layout requires a thorough investigation of specific aspect for which no previous experience is available. Herein, the interaction between propellers is analysed for a fixed propeller geometry, as a function of their mutual distance and compared to the acoustic pattern of the isolated one. The aerodynamic results have been obtained using a boundary integral formulation for unsteady, incompressible, potential flows which accounts for the interaction between free wakes and propellers. For the aeroacoustic analyses, the Farassat 1A boundary integral formulation for the solution of the Ffowcs Williams and Hawkings equation has been used. These results provide an insight into the minimum distance between propellers to avoid aerodynamic/aeroacoustic interaction effects, which is an important starting point for the development of distributed propulsion systems.

ОСНОВА МАТЕМАТИЧЕСКИХ МОДЕЛЕЙ ВЗАИМОДЕЙСТВИЯ КОЛЕСНЫХ ДВИЖИТЕЛЕЙ ЛЕСНЫХ МАШИН С ПОВЕРХНОСТЯМИ ДВИЖЕНИЯ

The purpose of the research, the results of which are presented in this article, is to analyze the scientific description of the properties of weak bearing movement surfaces of forest machines. The analysis has showed that universal mathematical models of the wheel propeller interaction with soil are based on the provisions of soil mechanics. This approach has been tested in the science of forestry production. It is successfully used by modern domestic and foreign researchers. However, with regard to the development and implementation of a mathematical description of interaction of ultra-low pressure
 wheeled mover (for example, in all-terrain wheeled vehicle) with supporting surfaces, it is necessary to take into account the ratio of the sides of the mover’s contact spot with the soil, since: mover pressure on the ground is defined as the partial load of a single mover and the area contact spots; the distribution of compressive stress over the depth of the soil mass depends on the ratio of the length and width of the contact spot; the bearing capacity characterizing the resistance to shear of the soil layers depends not only on its physical and mechanical properties, but also on the parameters of the contact spot, which is
 taken into account by special correction factors, the values of which depend on the aspect ratio of the contact spot. Soil rheology is considered to take into account the number of passes of a wheeled all-terrain vehicle along the route and its speed. One of the characteristics of the impact of the mover is exposure time. Value of the length of the contact spot is also used when determining the impact time of the mover on the soil.

Research on calculation methods of ship model self-propulsion prediction

The interactions between ships and propellers interfere with the performance of both. This paper aims to discuss the current methods of modeling ship–propeller interactions using computational fluid dynamics (CFD): the Reynolds Averaged Navier–Stokes equation (RANS) and body force methods. The fully resolved propeller method with the RANS solver, the prescribed body force method, and the boundary element method (BEM) and RANS coupled iterative body force method were used to predict the propulsive performance and calculate the self-propulsion point of a KRISO container ship model. For the RANS-BEM iterative body force method, a new method without nesting iteration is adopted to calculate the self-propulsion point. An additional discussion of self-propulsion factors is presented based on these results. Calculation results showed good agreement with model test results. The RANS method performs better at obtaining detailed flow field information and at analyzing the propeller plane wake fields on a propeller plane. The body force method has a unique advantage in terms of computational efficiency for performance evaluations of both ships and propellers.

Response of a direct-drive large marine two-stroke engine coupled to a selective catalytic reduction exhaust aftertreatment system when operating in waves

Large two-stroke marine diesel engines are used as the prime mover in the majority of ocean going commercial vessels and are currently facing new stringent NOx emission reductions. Selective catalytic reduction is an aftertreatment technology which is able to reduce emitted NOx at allowable levels. In most marine applications, the selective catalytic reduction system is placed on the high pressure side of the turbine, due to limitations at the exhaust gas temperature at the inlet of selective catalytic reduction system. In this article, the operation of a large two-stroke marine diesel with a selective catalytic reduction aftertreatment system, is investigated in heavy weather conditions. Operation of a vessel in heavy weather results in increased ship resistance, wave-induced ship motions, and a highly varying flow field in the propeller due to ship motions. This results in a fluctuation of propeller demanded torque and hence a fluctuation in engine load and exhaust gas temperature which may affect engine and selective catalytic reduction performance significantly. To investigate this phenomenon and taking into account the engine–propeller interaction, the entire propulsion system was modeled, namely the propulsion engine, the high pressure selective catalytic reduction system, the directly driven propeller, and the ship’s hull. A propeller model was employed to simulate the transient propeller torque demand and torque fluctuations due to ship motions. A three-dimensional six degrees of freedom panel code was used to calculate ship motions and wave added resistance in regular waves. The coupled model of the marine propulsion plant was validated against available measured data from a ship-board propulsion system on good weather conditions. The model was then used to simulate the behavior of the system during transient loading conditions in the presence of regular waves.

The effect of anisotropy on the interaction of the caterpillar propeller with the soil during the vehicle turn

The article discusses the force interaction of the caterpillar propeller with the ground during the vehicle turn. Since more than 70 % of soil reactions are inherently friction forces, the article is based on the Fyodor Opeiko mathematical theory of friction. According it, the resulting force and the moment of friction are interrelated quantities determined by the position of the instantaneous center of sliding. With increasing the moment of friction, the force decreases and vice versa. Since any caterpillar mover has lugs, its interaction with the soil in the longitudinal and transverse directions becomes different. In the frame-work of the adopted approach, the anisotropy of the force interaction of the propulsion with the soil is ex-pressed in various friction coefficients in the longitudinal and transverse directions. In addition, there is a fundamentally different nature of the interaction with the soil. In the transverse direction, a clean cut is observed. In the longitudinal direction, before the start of the cut, the soil is crushed due to its elastic properties. The article presents a mathematical model of the force interaction of a caterpillar propeller with soil, taking into account the anisotropy of the interaction. The elastic properties of the soil in the longitudinal direction are taken into account due to the variable coefficient of friction introduced under the integral sign. Hyperbolic tangent is used as a function, since it allows one to introduce the smallest number of empirical coefficients. Based on the presented mathematical model of force interaction, numerical calculations were performed. The results are presented in graphical form, which allows to visually as-sess the effect of anisotropy. The calculations showed that the differences in the values of the friction force due to taking into account anisotropy can reach 50 %, and the moment of friction up to 10 %.

Оценка показателей криволинейного движения автопоезда с помощью имитационного математического моделирования

Introduction: a widespread approach to the transportation of large-sized and heavy-weight indi-visible cargo on roads and terrain is the use of multi-axle wheeled transport complexes, which are road trains. At the same time, due to the significant overall dimensions, one of the most important properties of such machines is agility, that is, the ability to move along a trajectory of large curvature in a limited area, which is especially important in loading / unloading zones. Subject of research: the article presents an approach to predicting the indicators of curvilinear movement of multi-axle wheeled road trains, based on the application of the method of mathemati-cal modeling of the dynamics of body systems. Methodology and methods: the essence of the method is to create a mathematical model of the movement of a road train, represented by a system of rigid bodies, which are interconnected by kin-ematic and power connections. The simulation model developed within the framework of the study makes it possible to take into account with high accuracy the peculiarities of the interaction of the wheel propeller with the supporting surface, the redistribution of normal reactions between the sup-port modules, as well as the force factors arising in the coupling device and ensuring the interaction between the tractive vehicle and the trailer link. The mathematical description of the interaction of the propeller with the ground is based on the concept of “friction ellipse”. Using the presented mod-el, an assessment of the turnability of a wheeled road train equipped with a trailed link with swivel and non-swivel wheels was carried out. The required width along the tracks of the outer (running in) and inner (lagging) wheels was used as an assessment criterion. To assess the feasibility of using a trailed link with fully steered wheels and, accordingly, complicating the design of the machine, an additional assessment of the required power of the steering drive was carried out. Results and scientific novelty: a mathematical model of the dynamics of a road train was de-veloped. It makes possible to predict with high accuracy the indicators of curvilinear movement of wheeled vehicles, as well as to estimate the required power of the steering drive. Practical significance: a mathematical model of road train movement was developed, which al-lows a wide range of tests to be carried out to assess not only the indicators of curved-linear move-ment, but also the mobility of wheeled vehicles of any configuration as a whole.

A Study about Interaction of Propellers with Multiple Energy Saving Devices

A Study about Interaction of Propellers with Multiple Energy Saving Devices

Numerical Study on Flow Around Modern Ship Hulls with Rudder-Propeller Interactions

Reducing the fuel consumption of ships presents both economic and environmental gains. Although in the past decades, extensive studies were carried out on the flow around ship hull, it is still difficult to calculate the flow around the hull while considering propeller interaction. In this paper, the viscous flow around modern ship hulls is computed considering propeller action. In this analysis, the numerical investigation of flow around the ship is combined with propeller theory to simulate the hull-propeller interaction. Various longitudinal positions of the rudder are also analyzed to determine the effect of rudder position on propeller efficiency. First, a numerical study was performed around a bare hull using Shipflow computational fluid dynamics (CFD) code to determine free-surface wave elevation and resistance components. A zonal approach was applied to successively incorporate “potential flow solver” in the region outside the boundary layer and wake, “boundary layer solver” in the thin boundary layer region near the ship hull, and “Navier-Stokes solver” in the wake region. Propeller open water characteristics were determined using an open-source MATLAB code OpenProp, which is based on the lifting line theory, for the moderately loaded propeller. The obtained open water test results were specified in the flow module of Shipflow for self-propulsion tests. The velocity field behind the ship was recalculated into an effective wake and given to the propeller code that calculates the propeller load. Once the load was known, it was transferred to the Reynolds-averaged Navier-Stokes (RANS) solver to simulate the propeller action. The interaction between the hull and propeller with different rudder positions was then predicted to improve the propulsive efficiency.

Numerical analysis of propeller loading with a coupling RANS and potential approach

In this paper, we present a coupling potential and Reynolds-averaged Navier–Stokes (RANS) approach for the analysis of propeller loading and propulsion performance at self-propulsion condition. There is a presentation of a combination of unsteady RANS method for ship flow with free surface taking into account by volume of fluid method and Lifting Line Model for propeller operating behind ship. An intensified coupling strategy is proposed to simulate the propeller effect in the ship wake. The effective wake is re-examined through the iterations, and there is a presentation of the spatial distribution of propeller forces. Propeller unsteady loading of KCS test case is predicted by flow field from both Full RANS and the Coupling method and compared to experiment results. A circulation-based analysis is made to scrutinize the spatial distribution of propeller loading. The simulation results prove that the coupling method can estimate propeller’s loading and effect on averaged flow field. Ultimately, the coupling method is applied to design an optimal propeller accounting for hull–propeller interaction, which shows its potential for further integrated optimization application.

Mathematical model of interaction of a rolling elastic wheel with elastic-visco-plastic support base taking into account the history of loading

One of the main methods to predict permeability is a simulation of the motion of wheeled vehicles in different operating conditions, which are based on mathematical models of interaction between elastic tires with deformable irregularities of the support base. Currently in the theoretical study of the interaction of propellers with the ground formed two main directions: analytical method involving a mathematical description of the process under study and the finite element method based on computer simulation. The aim of this study is to develop a mathematical model of rolling elastic wheels on deformable rough reference base, taking into account the deformation of the contact patch at each end of the elementary playground. A mathematical model of the curvilinear rolling of the elastic wheel on an uneven elastic-visco-plastic support base is developed, taking into account the deformation of the contact spot in each finite elementary site; the influence of ground hooks on the parameters of the wheel movement; coupling properties of the support base in the horizontal direction under the action of a vertical load; change in the direction of radial and tangential reactions; elastic- visco-plastic properties of the support base;“history” of loading of each elementary platform of the support base; condition of the support base on its physical and mechanical characteristics.