Propeller Thrust Research Articles

Experimental and numerical investigation of the propeller thrust reduction in bollard pull condition

The polar ships are often in bollard pull condition, which is prone to induce propeller cavitation and cause thrust reduction, weakening the ship’s ice-breaking ability. Based on the model tests and numerical simulations, this paper aims to investigate the propeller thrust reduction in the bollard pull condition. Firstly, the test of a self-designed ice class propeller under different cavitation numbers is carried out. The thrust reduction phenomenon is successfully captured and the hydrodynamic characteristics are obtained. Subsequently, the simulation based on Star-CCM+ is performed. It is found that the propeller thrust decreases almost linearly after the cavitation number reaches a certain threshold. When the cavitation number is equal to 0.25, the thrust decreases to 38.1% of that in the open water condition. By analyzing the mechanism of thrust reduction, the main reason is recognized that the average pressure of the blade face decreases greatly due to the influence of the cavitation on the blade back.

Propeller Thrust Mechanism with Passive Orientation Control of Multi-rotor for Automatic Steering

Propeller Thrust Mechanism with Passive Orientation Control of Multi-rotor for Automatic Steering

Analytical model of no‐load axial force for electric propulsion conical motor in electric aircraft

AbstractIn the field of electric aircraft, the axial force of the conical motor is used to offset propeller thrust and reduce bearing wear. For the problem of accurate calculation of the no‐load axial force of the conical motor, combined with the characteristics that the rotor magnetic bridge of the hybrid conical inner‐mounted permanent magnet synchronous motor (HC‐IPMSM) is easy to be saturated and difficult to be calculated analytically, an equivalent analytical calculation method is proposed. According to the principle of constant air‐gap magnetic flux, the HC‐IPMSM is equivalent to many cylindrical surface‐mounted permanent magnet synchronous motors (CY‐SPMSM), and an analytical model is gained. Combining with the scalar magnetic potential Laplace equation and Poisson equation, the air‐gap flux density distribution on the rotor surface is calculated. And finally, the no‐load axial force of the motor is obtained by using the cone angle and the Maxwell stress method. Simulation and experiments verify the correctness and validity of the analytical model.

НОВІ МАТЕМАТИЧНІ МОДЕЛІ КОЕФІЦІЄНТУ УПОРУ І КОЕФІЦІЄНТУ МОМЕНТУ НА ВАЛУ ГРЕБНОГО ГВИНТА СУДНА

Solving the problems of course stabilization of the ship, dynamic positioning, the ship divergence dynamics, the construction of effective simulators and autopilots are not possible without the use of adequate mathematical models of the dynamics of the ship. The presence of the latter is also a necessary condition for studying various ship maneuvers, in particular, such as circulation, Kempf zigzag, slowing down, acceleration, etc. Improving control methods, including trends towards full autonomy of ships, necessitates constant improvement of mathematical models of the ship's propulsion complex. The general mathematical model of ship dynamics includes mathematical models of inertial and non-inertial forces acting on the ship. The latter include, in particular, hydrodynamic forces on the hull, forces caused by the operation of the ship's rudders and propellers, aerodynamic forces acting on the ship's hull, and forces caused by the ship's sailing rig. Mathematical models for non-inertial forces have an empirical multilevel character, include mathematical models of various quantities and parameters, and are built on the basis of experimental data processing or methods of computational hydrodynamics. Therefore, the improvement and refinement of each such model leads to the improvement of the mathematical model as a whole and is an important scientific and actual practical task. An important task is also to bring the specified mathematical models to a form that is convenient for use. In this work, new adequate, easy-to-use, mathematical models of the thrust coefficient of the propeller and the torque coefficient on the propeller shaft were obtained using regression analysis methods, and their excellent consistency with known mathematical models was shown on specific examples. For the main types of commercial vessels, the numerical values of the coefficients of the models are given, and the values of the propeller advance ratio of the zero thrust and zero torque on the propeller shaft are determined. This made it possible to obtain the condition of normal accident-free operation of the propulsion complex of the ship, which must be satisfied by the speed of the ship and the frequency of rotation of the propeller shaft, at different values of the drift angle and angular speed. Keywords: mathematical models, ship propellers, propeller thrust coefficients, propeller shaft torque coefficients.

Penerapan Kawat Litz Pada Motor BLDC Untuk Peningkatan Gaya Dorong Per Daya

Copper loss can cause a decrease in performance in BLDC motors, so efforts will be made to reduce copper loss by using Litz wire. Additionally, there have been studies that simulate the performance of Litz wire, but they have not been directly applied, especially to propeller thrust. The objective of this research is to implement Litz wire in a BLDC motor and analyze its performance for an increase in propeller thrust per power. The BLDC motor is wound with single wire and Litz wire. The analysis conducted compares the resistance, copper loss, thrust force, and thrust-to-power ratio of the single wire and Litz wire with the same wire cross-sectional area. The BLDC motor is equipped with a propeller to measure the thrust force. The average resistance of the single wire is 0.43 Ohms, while the Litz wire is 0.38 Ohms. The copper loss of the Litz wire is 7% lower than a single wire. The Litz wire exhibits a 3% improvement in thrust force compared to the single wire in the testing. The thrust-to-power ratio of the Litz wire is also 3% better during the testing.

Acoustic Field Radiation Prediction and Verification of Underwater Vehicles under a Free Surface

This study aimed to examine the acoustic field radiated by propellers and underwater vehicles. For the verification of sound radiation in underwater vehicles, numerical methods are widely used in addition to experiments and propeller blade frequencies for calculation and validation. Numerical convergence and accuracy are more important for near-field and far-field problems. This paper uses the boundary element method (BEM) to assess the convergence of the finite volume method (FVM). In this study, the FVM, including the Reynolds-averaged Navier–Stokes method and the Ffowcs Williams–Hawkings (FW-H) acoustic model, is used to investigate the influence of various geometric inflows on the hydrodynamic and noise performance of the propeller. Then, the sound radiation of the FVM is compared with the BEM at the far field to determine the number of meshed elements. Furthermore, spectral analysis is being conducted to examine the noise generated by the underwater vehicle and propeller. The objective is to investigate the influence of the free surface on propeller efficiency. After verifying the numerical simulation, the results indicate that a relationship can be established between water pressure and propeller thrust under specific conditions. This relationship can be used to estimate the magnitude of propeller thrust at different water depths. The simulated results of propeller thrust, torque coefficient, propulsion efficiency, and sound radiation in this study are consistent with experimental values. This demonstrates the accuracy and practicality of the findings of numerical procedures in engineering applications.

Acoustic signature of sUAS rotors undergoing edgewise forward flight

This presentation shares preliminary experimental results from a new sUAS rotor test rig installed in UNSW’s Anechoic Wind Tunnel (UAT). This new test rig allows acoustic and aerodynamic performance testing of small drone-scale rotor blades under edgewise forward flight conditions at a range of shaft angles. The study of sUAS rotors under edgewise forward flight presents asymmetric inflow to the rotor and unsteady loading on the blades themselves, with different flow conditions experienced by the advancing and retreating rotor blades. This means the acoustic signature of a rotor undergoing edgewise flight is significantly changed compared to static thrust or axial flight conditions of drone rotors or propellers. This presentation aims to outline changes to the acoustic signature of a collection of conventional off the shelf (COTS) rotor and propeller designs between static, axial flight and edgewise flight conditions, coupling this with rotor performance metrics.

Bi-layer sizing and design optimization method of propulsion system for electric vertical takeoff and landing aircraft

Electric vertical takeoff and landing (eVTOL) aircraft is a promising solution for future urban air mobility, but it suffers from insufficient energy and power density as opposed to fossil fuel-based aircraft. This paper proposes a bi-layer design optimization method for electric propulsion systems. To tackle the issue of high-dimension design parameters and multiple performance constraints, the design process is divided into two parameter optimization problems. In the upper layer, only scalar parameters of components are considered to determine a feasible sizing result subject to energy-flow limits. The outcome of this layer further serves as the initial guess of the lower design layer. The constraints of power conservation and conversion among components are taken into account. The optimization is scheduled in a cascaded paradigm that maximizes the total energy efficiency with minimized total weight. The blade-element momentum method is employed to estimate propeller thrust and torque coefficients. The proposed method is applied to a tilt-wing eVTOL. The sizing results shows that the eVTOL mass is reduced by 11.66% as opposed to the benchmark method. The proposed method provides a generic framework for sizing and design optimization independent of configuration and mission profiles.

DEVELOPMENT OF PROPELLER POWERED VEHICLE

— Many experiments have been conducted on wind-driven vehicles in the last decade, and wind-driven vehicle systems have moved faster along their paths than wind. Here, the car is powered by an aircraft propeller that is used. Therefore, we called it a "propeller-driven engine." This concept comes from merging the propulsion and automobile fields. A propeller-driven car is one type of simple power vehicle. This vehicle can be used as a ground vehicle. In the current scenario, the construction of a vehicle is a very difficult challenge because of its complex design, which requires considerable time and precaution. It cannot be constructed by a single engineer or an expert. A propeller-powered vehicle is one of the solutions to these problems. In defense, shifting a vehicle is a very complex task, and the propeller power car is the solution for which it can be easily dismantled and assembled. The propellerpowered car has a simple design. A vehicle carries 100 kg of weight, and its seating capacity is one. A propel-driven vehicle operates as a three-wheeler vehicle using aircraft propeller thrust. A propeller is placed in the rear section of the car, which gives power to the car. Propellers generate thrust by rotating an airfoil in a circle, which generates thrust by accelerating the airflow backward away from the propeller. The construction of a vehicle is less timeconsuming and easier to assemble.

Propeller thrust tower crane slewing mechanism model identification

Any study of the dynamics and control of mechanical systems is based on adequate mathematical models that contain the dynamic parameters of the system under study. Their evaluation, in particular for the tower crane boom system, is a particularly relevant scientific and practical problem, the solution of which will provide the basis for further calculations of the optimal modes of movement of the tower crane slewing mechanism. The research aims to determine the dynamic parameters of the installation (moment of inertia of the slewing mechanism J, torque of dry friction forces M0, driving torque coefficient K1) and to plan experimental studies. The experimental method, numerical optimization methods (in particular, the modified Rot-Ring-PSO method), and statistical methods were used to conduct the research. Based on the results of the experiments, the dynamic parameters of the mathematical model of the laboratory installation of the tower crane slewing mechanism with propeller thrust were identified. The criterion that evaluates the identification error of the parameters K1, M0, and J was formed and minimized using the Rot-Ring-PSO algorithm. Plots of the kinematic characteristics of the movement of the boom system in terms of the angle of rotation of the boom and the speed of rotation of the boom were constructed. When processing the experimental data, the dependence of the error values on the supply voltage of the propeller drive was revealed. The error in the boom rotation speed at the drive supply voltage of 90% (compared to the voltage variant of 40%) decreased by almost 15%, and the error in the boom rotation angle at the drive supply voltage of 90% (compared to the supply voltage variant of 40%) decreased by almost 3 times. The regularity has been confirmed that with an increase in the supply voltage, the error value of the system decreases. In the course of processing the experimental studies, the dynamic parameters of the installation were identified: K1=4.80‧10-8 V/(rpm)2, M0=34.519 Nm, J=24.21 kgm2. The obtained results will be used to optimise the plant’s motion modes, and the developed identification algorithm can be used for other similar problems

Variations Rake Angle Propeller B – Series Towards Performance and Cavitation with CFD Method

Fuel consumption is most widely used in ship propulsion system, therefore, in ship propulsion system must be considered and designed as efficiently as possible. Propeller is one of the mechanical components on a ship, which can run ships from one place to another. The most important thing in a propeller is the mechanical properties or strength of the propeller in accepting the load to be able to run the ship. Another factor that affects mechanical propeller properties is the propeller design itself. In propeller design, one thing that can be considered is the rake angle of propeller. The rake angle is the slope angle between the propeller blade and the propeller center. The rake angle on the propeller is used to increase the amount of mass water used to produce thrust that needed by ship. Reducing the rake angle can increase the efficiency of the B-Series propeller slightly. Previous research has analyzed the effect of variations in rake angle to determine the relationship between thrust and fluid flow in the B-series propeller, but for the cavitation that occurs in the propeller has not been analyzed. In this research, variations ware made from the B-Series propeller rake angle to obtain propeller thrust and cavitation values. The analysis carried out in this study is to use the CFD (Computational Fluid Dynamic) method and the results obtained from the simulation with greatest thrust and efficiency, that is in the 5º rake angle variations of 2310,273 KN and 70% efficiency, while the smallest thrust value is variation of rake angle 25º for 1110,933 KN. Then for the largest cavitation level in the variation of the 25º rake angle and the smallest at the 15º original rake angle.

Comparison between the two methods of optimization: Genetic algorithm (GA) and ant colony algorithm (ACO) for the propulsion system of UAV

A propeller generates lift in the direction of revolution, similar to a revolving wing. Many previous propeller optimization techniques exist; nevertheless, they often find the optimal thrust coefficient at a constant power coefficient and vice versa. Using two types of algorithms, the genetic algorithm (GA), and the ant colony algorithm (ACO), and comparing with each other, this study will discover the optimal value of the thrust coefficient and the power coefficient combined to obtain the optimum value of the thrust and the lowest value of the power at the same time. A Simple Blade Element Theory Blade served as the foundation for all assumptions. This article examined over 80 various designs, brands, and types of propellers in a 2-blade configuration with diameters ranging from 2.5 to 19 inches and varying pitch values. The data for the baseline propeller was obtained from the UIUC Propeller Database. The inputs for the optimization are the propeller type, diameter, pitch angle, rotational speed, thrust coefficient, and power coefficient. The results show that by determining the factor of interest in the thrust coefficient (FITC), the algorithm can find the optimal propeller specifications. When the (FITC) is 100%, the algorithm will ignore the effect of the power coefficient and vice versa. In the instance (FITC) is 100 percent, the genetic algorithm performed much better than the ant colony algorithm (ACO). But the Ant colony algorithm is more accurate than the genetic algorithm.

Numerical Study of Kaplan Series Propeller using CFD: Effect of Angle of Attack and Number of Blade Variations

Kaplan series propeller has the potential to improve ensuring the high ship propulsion performance of the operation. In this study, a Kaplan propeller is evaluated with a Controllable Pitch Propeller (CPP) behavior such as angle of attack and the number of blades. The propeller blades which are studied are 3, 4, and 5 blades with the angle of attack about 10.3⁰, 15.3⁰, and 20.0⁰. The method in this study is using Computational Fluid Dynamic (CFD) simulations. Moreover, surface pressure, thrust, torque, and efficiency are evaluated due to the influence of the angle of attack variations. It has been found that varying the angle of attack significantly affects the distribution of the pressure surface of the propeller. The pressure gradually increases at the higher level of the angle of attack. Furthermore, it is well known that variations in the angle of attack and the number of blades significantly affect propeller performance as expressed by propeller thrust and torque values. Thrust and efficiency tend to increase at higher levels of the angle of attack. However, it tends to decrease at the propeller with more blades on it

Coordinated Symmetrical Altitude Position and Attitude Control for Stratospheric Airship Subject to Strong Aerodynamic Uncertainties

The stratospheric airship has important value in both commercial and military use. The altitude position control is very crucial for the airship to conduct specific missions, which is also a challenge because of both the severe relative aerodynamic mismatches and the large lag due to the quite low speed of the airship within 15 m/s. In this paper, a coordinated altitude and attitude control method was proposed to realize satisfactory altitude position control while maintaining the attitude stability by properly employing the two actuators, the propeller thrust and the elevator, in a consistent manner. In this process, the references for the vertical speed and the pitch were specified in a straightforward way of proportionating them by considering their physical characteristics and the inherent symmetrical relationship between them, which can be obtained through the kinematics. An extended disturbance observer was used to eliminate the severe aerodynamic uncertainties to symmetrically distribute the two actuator outputs by dynamically decoupling the vertical speed and the pitch angular rate loops into the two independent integrators. As a result, the explicit proportional controllers were sufficient to realize efficient command tracking. Rigorous theoretical investigation was provided to symmetrically prove the quantitative bounded property of the estimation and tracking errors. The simulation results demonstrated the effectiveness of the proposed approach, which can realize a 500-m altitude difference tracking within 200 s with less than 0.5 deg/s pitch angular rate.

Numerical Investigation of Self-Propulsion Performance and Noise Level of DARPA Suboff Model

Propulsion noise is an enduring problem of significant military and environmental importance. Hence, it is crucial to investigate propeller noise characteristics. In this study, the hydrodynamic performance and noise level of the DARPA (Defense Advanced Research Projects Agency) Suboff submarine with the E1619 propeller were analyzed. The hull resistance and propeller hydrodynamics were studied separately, and the numerical results were validated using available experimental values. The self-propulsion point was determined by matching the hull resistance and propeller thrust following ITTC (International Towing Tank Conference) convention. Based on hydrodynamics and acoustic Ffowcs Williams–Hawkings (FW–H) models, the underwater-radiated noise characteristics in the self-propulsion state were simulated. The calculations indicated that the contribution of the quadrupole term in the FW–H equation is not negligible in the high-frequency band. Compared with the noise of open-water propellers, the spectrum of the E1619 propeller in its self-propulsion state is more complex, and the upstream noise is amplified.

Hydrodynamic Tests of Innovative Tourist Submarine

This paper deals with the resistance, towing, seakeeping, and open water propeller tests of an innovative tourist submarine model. Tests were performed in a 276 m long towing tank. As the submarine model is a complex structure composed of various parts attached to the pressure hull, the largest possible model, in the scale of 1:5.0, was produced, considering the towing tank depth and the capabilities of the measurement equipment. Resistance tests were performed in deep water and on the surface in calm water. The tested speed range in both cases was up to 5.5 knots. To ensure the avoidance of free surface effects, resistance tests in deep water were performed for different draughts and then extrapolated to infinite water depth. Smaller effective powers were found for the surface condition. The results are compared to an independently performed computational fluid dynamics (CFD) analysis using OpenFOAM. A fair agreement between the experimentally and numerically predicted effective power is found, while the reasons for the differences found are explained. The free submarine model was towed with a rope performed for the speed range 1.7 kn–3.5 kn, and the towing force in the rope was measured. Seakeeping tests in irregular beam waves at zero speed were performed to check the flooding risk on open hatches. Open water tests of the main thrusters for propelling the submarine were conducted, indicating that both power demand and propeller thrust are slightly larger compared to the initial estimates.

Причины различий между коэффициентами упора винта при работе за корпусом судна и в свободной воде на швартовых

Object and purpose of research. The object of research is the results of self-propelled ship tests in bollard-pull conditions. The purpose is to analyse the hydrodynamic sources giving rise to differences between propeller thrust coefficient in open-water and behind-hull conditions. Materials and methods. Analysis based on the ideal propeller theory shows that the velocity ΔV of inflow on propeller operating behind ship hull in bollard-pull conditions caused by a system of sinks, ensuring flow attachment to hull surface, has a finite value and is actually the effective wake. The wake velocity for an open-water propeller is equal to the behind hull velocity. The open-water propeller thrust coefficient at advance ratio (formula) is due to the opposed jet of its reversal. It is shown that the thrust coefficient deviations at self-propelled tests in open-water has to do with the specifics of propeller thrust variations in the operating area adjacent to bollard-pull conditions. Boundaries of the operating area where the opposed jet affects the propeller curve at self-propelled tests are defined. Practical conclusions and recommendations are given following from the obtained data. Main results. The source of discrepancies between self-propelled test results for open-water propeller in bollard pull conditions and close operating area has been found. Recommendations are given on updating the test procedures for propeller and self-propelled model tests Conclusion. The paper is expected to be useful for understanding the ambiguity of self-propelled test results.

An improved body force method for simulation of self-propulsion AUV with ducted propeller

The body force method (BFM) is an efficient computational method used for maneuvering simulations of marine vehicles with ordinary propellers. In this paper, an improved BFM is proposed to perform maneuvering simulations of a self-propelled AUV with a ducted propeller. Initially, the conventional BFM is applied to numerically investigate the open water performance of a ducted propeller(No. 19A+Ka4-70). However, significant prediction errors have been observed, which were mainly caused due to ignorance of the interaction between the duct and the propeller. To increase the prediction accuracy, an improved BFM is proposed to perform maneuvering simulations of the ducted propeller AUV by considering the mass flow correction. In addition, the external diameter of the actuator is proposed to be a function of real-time advance velocity. To investigate the efficacy of the proposed method, the simulated results have been compared with the model testing carried out in a towing tank and with the discretized propeller method. The proposed improved BFM is used to simulate the 20°/20° zigzag tests of AUV in both vertical and horizontal planes with different advance speeds. Simulated results, particularly propeller thrust, advance speed, pitch (or yaw), resistance, and especially duct thrust of AUV have significantly improved as compared to the conventional BFM. The improved BFM results were found in close agreement with discretized propeller method and thus, the proposed method is considered a highly efficient and computationally cost-effective method to perform maneuvering simulations of ducted-propeller marine vehicles. The present work can contribute to the fast optimization of the manoeuvrability of marine vehicles with ducted propeller.

Aerodynamic Effects of a Wing Surface Heat Exchanger

One challenge for the design and analysis of hybrid electric aircraft configurations is an increased demand in the rejection of excess waste heat. A wing surface heat exchanger concept, which is explored as part of the IMOTHEP project, foresees transferring heat from the propulsive electrical components to the wing surface of the aircraft. Here, heat is mainly dissipated and transported by forced convection. The present study focuses on the analysis of the impact of heat rejection via the wing surface on the wing’s heat transfer and aerodynamic efficiency characteristics. For this purpose, RANS CFD studies of 2D airfoils and a 3D wing propeller geometry of a regional turboprop configuration in representative flight conditions (take off, cruise, and taxi in) are carried out. For each condition, the influence of defining parameters, such as altitude, freestream velocity, angle of attack, surface temperature, and propeller thrust is explored. It is shown that, when increasing the wing surface temperature compared against the freestream temperature, the aerodynamic efficiency of the wing deteriorates for all flight conditions. In reference cruise conditions for example, the lift-to-drag ratio decreases by 4%, while the average heat transfer coefficient is reduced by almost 20% when increasing the surface temperature by 300 K. Furthermore, the propeller slipstream enhances the wing’s heat transfer capacity significantly.

Novel combinator surface concept for efficiency optimization of ship propulsion system

This paper describes a methodology to design and generate a novel optimal combinator surface suitable for mechanical propulsion systems on ships with controllable-pitch propellers (CPPs). The combinator surface is an extension and enhancement of conventional combinator curves, considering the effect of both the advance speed and the propeller thrust for the selection of optimal operation setpoints for propeller RPM and pitch. The generation of optimal combinator surface does not require the estimation of the ship resistance, wake fraction, and thrust deduction fraction, enabling automatic reference setpoint searching during the steady state as well as acceleration and deceleration. The optimization algorithm is created based on the maximization of the power and propulsion efficiency, taking the prime mover and propeller constraints into consideration. The proposed methodology is illustrated using a longliner as a case study ship. From thrust and ship speed analysis, the proposed combinator surface method benefits vessels working with frequently changing operations. The ship propulsion efficiency is improved greatly for ship acceleration. The comparison of the efficiency performance using the conventional combinator curve and the proposed combinator surface demonstrates that the new concept of combinator surface enables more efficient propulsion for ships operating under varying loading and sea state conditions.