Fixed Pitch Propeller Research Articles

A Comparison of Isolated and Ducted Fixed-Pitch Propellers under Non-Axial Inflow Conditions

A strong interest in highly-efficient, small-scale propeller configurations can be recognized, especially due to the currently growing number of and usage possibilities for unmanned aerial vehicles (UAVs). Although a variety of different propulsion concepts already exist on the market or are discussed in the literature, there is still a demand for a systematic investigation to compare such configurations, in particular, small-scale propellers with a fixed pitch, which are analyzed in this work. Therefore, different configurations of small-scale propellers with a fixed pitch are analyzed in this paper. They were operated as isolated single propellers and as ducted propellers in a cylindrical wing. Furthermore, due to their flight envelope, UAVs are likely to operate at highly inclined inflow conditions and even under reverse inflow. These non-axial inflow conditions have a major influence on the flow field around a propeller. In order to investigate this influence, all analyses were performed at a range of inflow angles in relation to the propeller axis from αdisc=0° to 180°.

A nonlinear optimization tool to simulate a marine propulsion system for ship conceptual design

An optimization tool is developed to simulate the performance of a marine propulsion system of a fishing trawler for ship conceptual design. It consists of two modules implemented in Matlab. The first optimization module simulates the performance of a high speed turbocharged four-stroke marine diesel engine along the engine load diagram. It couples 1D engine simulation tool and a nonlinear optimizer to minimize the BSFC of the marine engine and to verify the limitations of emissions defined by international organizations, by optimizing turbocharger and injection parameters. The second module assists in the selection of a suitable fixed pitch propeller from Wageningen B-series at the ship design speed at engine operating point with minimum fuel consumption and by verifying the propeller cavitation, strength and noise issues, instead of only maximizing the propeller efficiency or minimizing the BSFC as considered in previous researches.Then, the objective of the propeller optimization module is changed to compute the propeller performance by (1) maximizing the propeller efficiency (2) minimizing the BSFC, for the purpose of comparison with the current study. The current case shows a significant reduction in the amount of fuel consumed by around 30% in comparison with the other two cases.

Quadrotorlarda PID Algoritması Kullanarak Diferansiyel Morphingin Yanlamasına Uçuş Üzerine Etkisinin İncelenmesi

Quadrotor is unmanned aerial vehicles that are widely used in military and civil fields. Quadrotors differ from conventional helicopters, which use rotors that are able to vary the pitch of their blades dynamically as they move around the rotor hub. Quadrotors generally use two pairs of identical fixed pitch propellers; two clockwise (CW) and two counterclockwise (CCW). These use independent variation of the speed of each rotor to achieve control. In this study, the quadrotor lateral flight and the effect of morphing on this flight were investigated. Morphing is called the change of unmanned aerial vehicles in their geometry. Newton-Euler method is used to create the quadrotor model. However, since the quadrotor is a system with non-linear dynamics, motion equations are converted to linear equations. The quadrotor full model was drawn in the Solidworks program, including batteries, controllers and propellers, in accordance with its actual dimensions. State space model approach was used in simulations in Matlab / Simulink environment. The value of mass and inertia moments from the Solidworks program is used in the state space model. Proportional integral derivative (PID) was used as the control algorithm. PID is an algorithm widely used in industrial applications. PID is preferred because it is strong, fast and simple. The system to which PID will be applied must be linear. The PID coefficients Kp, Ki and Kd are important for the stable operation of the system. Appropriate values should be chosen. In this study, lateral flight performance was monitored using differential morphing and PID algorithm and the results were presented.

Instantaneous Rotational Speed Algorithm for Locating Malfunctions in Marine Diesel Engines

This article suggested broadening the standard methods for diagnosing the technical condition of diesel engines to include an analysis of the instantaneous rotational speed of compression combustion engines with the use of a novel algorithm. The authors revised the subject concerning the use of the analysis of instantaneous changes in the rotational speed of an engine when assessing its technical condition and the location of the malfunction. An algorithm and its practical implementation in a prototype diagnostic system called SpeedMA were presented. This article reported the test results of the prototype in the context of indicating the engine cylinder in which ignition failed to occur. Tests were carried out for two marine engines: a low-speed trunk engine directly driving the fixed-pitch propeller and a medium-speed trunk engine driving the alternator. For each case, an analysis was carried out for different engine loads and at individual cylinders in which combustion failed to occur. The experimental results showed an unambiguous relation between the combustion process of the examined engines and changes in the instantaneous rotational speed. The results also confirmed the usefulness of the proposed method and showed the correct operation of the presented diagnostic algorithm. The proposed diagnostic system could be used during the operation of engines running in real ship engine rooms.

Концепт сухогрузного многоцелевого судна проекта RSD32M типа «НАВИС» класса «Азовский пятитысячник»

Середній вік суден класу «Волго-Балт» / «Сормов-ський» в даний час складає більше за 30-35 років, що цілком обумовлює загальну необхідність поповнення флоту новими суднами з такою ж річковою вантажопідйомністю – суднами проекту RSD32M. Концепт є розвитком проектів RSD18 (типу «UCF») і RSD32, створених Морським Інженерним Бюро в 2005-2006 роках, і «однокласником» проекту RSD17 (типу «Мірзага Халілов») і суден типу «Валдай» і «Русич». Судно «південного» типу, тому вибір класу судна за районам плавання (R2) і за льодовою категорію (Ice1); застосування люкових закриттів знімного типу з козловим судновим краном; середньооборотні дизеля в якості головних двигунів і які вже стали класичними для цього типу суден повноповоротні гвинто-рульові колонки з гвинтами фіксованого кроку. Виконано детальний аналіз основних характеристик, а також їх порівняння з характеристиками суден-аналогів. Коефіцієнт викорис-тання водотоннажності за дедвейтом є найкращим на всіх розглянутих осадках. Питомі показники при інших осадках проекту RSD32M кращі, ніж на інших суднах аналогічного класу. При роботі в портах Каспій-ського і Азовського морів проект RSD32M матиме економічні переваги в порівнянні з усіма іншими суднами.

Рабочие режимы и ресурсные показатели дизелей 9L28/32А-F фирмы MAN-B&W в процессе длительной эксплуатации

The article describes L28/32 and L23\30 MAN-B&W diesel engines widely used by many shipping companies owing to high maintenance and service ability of simple, but sufficiently reliable engine parts. As for a medium speed 4-stroke engine, diesels have optimal power forcing characteristics, high fuel saving and durable overhaul time for essential parts. There have been considered the positive and negative features of the engine, which are also important technical indicators, in comparison with the designed samples when choosing the base engine. The analysis of operational durability, the typical failures of the cylinder-piston group and other essential parts 
 of 9L28/32A-F MAN B&W engines under different operation modes and loads have been given. During the first overhaul there has been demonstrated the working state of the cylinder-piston group of two engines after 22424 and 22672 h instead of recommended 12000 h for heavy fuel oil. Owing to diagnostic control and monitoring cylinder liner and piston rings assembly, overhauling was made only by condition mode. Maximum working time (40084 h) without cylinder overhaul was reached at suspend power of 75% Pe nom. At a tanker «Georgiy Froier» during 12 years of operation and 64500 working hours only 15pistons were overhauled instead of 48recommended, with changing 39 piston rings instead 194 recommended. In the future, the engines worked up to 
 100 thousand hours without top overhaul, with high resource parameters of the main parts on two engines in the shipping company. The operational problems of the engines with isobaric boost system on ships with a fixed-pitch propeller were identified and considered.

Experimental Investigation of Propeller Induced Flow on Flying Wing Micro Aerial Vehicle for Improved 6DOF Modeling

In this research effect of propeller induced flow on aerodynamic characteristics of low aspect ratio flying wing micro aerial vehicle has been investigated experimentally in subsonic wind tunnel. Left turning tendencies of right-handed propellers have been discussed in literature, but not much work has been done to quantify them. In this research, we have quantified these tendencies as a change in aerodynamic coefficient with a change in advance ratio at a longitudinal trim angle of attack using subsonic wind tunnel. For experimental testing, three fixed pitch propeller diameters (5 inch, 6 inch and 7 inch), three propeller rotational speeds (7800, 10800 and 12300 RPMs) and three wind tunnel speeds (10, 15 and 20 m/s) have been considered to form up 27 advance ratios. Additionally, wind tunnel tests of 9 wind mill cases were conducted and considered as baseline. Experimental uncertainty assessment for measurement of forces and moments was carried out before conduct of wind tunnel tests. Large variation in lift, drag, yawing moment and rolling moment was captured at low advance ratios, which indicated their significance at high propeller rotational speeds and large propeller diameters. Side force and pitching moment did not reflect any significant change. L/D at trim point was found a nonlinear function of propeller diameter to wingspan ratio D/b, and propeller rotational speed. Rate and control derivatives were obtained using unsteady vortex lattice method with propeller induced flow effect modeled by Helical Vortex Modeling approach. In this research, we have proposed improved 6-DOF equations of motion, with a contribution of advance ratio J. It is concluded, that propeller induced flow effects have a significant contribution in flight dynamic modeling for vehicles with large propeller diameter to wingspan ratio, D/b of 22% or more.

CFD Modeling and Study of Additional Medium Jet Impact on the Blade of the Propeller

The paper analyzes the possibility of improving the efficiency of the propeller as one of the main directions of improving the main propulsion plant. The requirements of the MARPOL-73 convention, as amended, and the need to adapt the main propulsion plant to changing operating conditions require improving the design of the fixed pitch propeller. The paper presents the results of CFD modeling and studies of the flow around the NACA-2412 blade with the supply of additional medium along the chord, regarding the suction surface. This work is an adaptation of the method used in aviation for increasing lift force by blowing the boundary layer. The magnitude of the lift force has a significant impact on the dynamic characteristics of the propeller. CFD modeling of the propeller blade profile in compressible and incompressible media, and also the calculation of the parameters of the NACA-2412 profile with the supply of additional medium were performed. The modeling results are confirmed by comparison with known modeling results for compressible media and experimental data. The possibility of increasing the efficiency of the propeller due to the jet supply of additional water to the suction surface of the blade along the chord has been proved. The results of the work can be used to control the operating mode of the main engine by changing the thrust and the hydrodynamic torque of resistance to rotation of the propeller.

НОВЫЙ РОССИЙСКИЙ ЛЕДОКОЛ«ИВАН ПАПАНИН»

In honor of Ivan D. Papanin, on the occasion of his 125th anniversary, on October 25, 2019, a unique scientific military ship “Ivan Papanin”, 110 meters long and displacement is 9000 tons, was launched in St. Petersburg. Like the famous polar explorer, one of the pioneers of the Arctic, the vessel will also be the first, since such icebreakers have not yet been built in Russia, because this is not just an icebreaker, but also a tugboat and a patrol ship. The icebreaker “Ivan Papanin” is designed to perform various civilian and defense tasks: navigate ships, transport cargo, participate in rescue operations and scientific research. As a warship and formidable border guard, the ship can repulse any troublemakers in the North. It is characterized by high reliability, redundancy of the main engines, the use an electric propulsion system, fixed-pitch propellers, so that the system operates reliably and for a long time. In addition, the ship is equipped with modern communications and navigation systems. Place of work – Arctic, which I.D. Papanin devoted all of himself. The area is not limited. Autonomy of swimming is 60 days. The ship Is able to cope with two-meter ice.

Aerodynamic Performance of Variable-Pitch Propellers for High-Altitude UAVs

As the air density changes dramatically from high to low altitude, the matching of high-altitude propeller and electric motor under low-altitude condition is one of the main challenges that aerodynamic design of high-altitude propeller faces. To solve this problem, variable-pitch propeller is the most commonly used and feasible solution. In this paper, the Reynolds-average Navier-Stokes solver and an efficient surrogate-based optimization toolbox are used for the aerodynamic design of a fixed-pitch propeller. Based on the optimal fixed-pitch propeller, a series of pitch angle are employed to obtain the variable-pitch propeller with maximum thrust. Then, the aerodynamic characteristics of fixed-pitch propeller and variable-pitch propeller under typical working conditions are studied and compared. The results show that under the condition of low-altitude and low wind speed, the fixed-pitch propeller reaches the rated torque of the electric motor at a lower rotational speed, resulting in a lower shaft power and thrust. By adjusting the pitch angle, the variable-pitch propeller can achieve higher rotational speed under the same rated torque constraints, thereby absorbing more shaft power and achieving larger thrust. The lower the altitude, the more obvious the advantage of the variable-pitch propeller. Compared with fixed-pitch propeller, the maximum relative increment of the maximum thrust can reach more than 80% for variable-pitch propeller. It is concluded that variable-pitch propeller can significantly improve the matching of propeller and electric motor, bringing wider flight envelope of UAVs.

Simulation of concentrations harmful compounds from main ships propulsion engine cooperating with a fixed pitch propeller in dynamic states

The article presents a mathematical model of a marine propulsion system and a computer program based on the LabVIEW environ-ment. For a purpose of model construction, a ships hull resistance was identified and an approximation equations of the Wageningen institute for ship propellers were used. The ships motion equations were used to build the propulsion system model. On the basis of conducted tests of Sulzer 6AL20 / 24 marine engine, a map of concentrations harmful compounds was created in various load state and transferred to a computer program.

Development of offers on application of additional jet impact on the fixed pitch propeller for the purpose of rational use of the power of the main engine

The choice of the design operational points of the main engine to achieve the design speed of the ship determines the efficiency of the propulsion plant. At the same time, the limits recommended by the engine manufacturer for selecting the design operational points do not fully take into account current trends and can be changed. The problem of the rational use of the nominal power and specified maximum continuous rating power of the main engine operating on a fixed pitch propeller is relevant.

Improving accuracy and efficiency of CFD predictions of propeller open water performance

This research proposes mesh and domain optimization strategies for a popular Computational Fluid Dynamics (CFD) technique to estimate the open water propulsive characteristics of fixed pitch propellers accurately and time-efficiently based on examining the effect of various mesh and computation domain parameters. It used a Reynolds-Averaged Navier-Stokes (RANS) solver to predict the propulsive performance of a fixed pitch propeller with varied meshing, simulation domain and setup parameters. The optimized mesh and domain size parameters were selected using Design of Experiments (DoE) methods enabling simulations in a limited memory and in a timely manner without compromising the accuracy of results. The predicted thrust and torque for the propeller were compared to the corresponding measurements for determining the prediction accuracy. The authors found that the optimized meshing and setup arrangements reduced the propeller opens simulation time by at least a factor of six as compared to the generally popular CFD parameter setup. In addition, the accuracy of propulsive characteristics was improved by up to 50% as compared to published simulation results. The methodologies presented in this paper can be similarly applied to other simulations such as calm water ship resistance, ship propulsion etc. to systematically derive the optimized meshing arrangement for simulations with minimal simulation time and maximum accuracy. This investigation was carried out using a commercial CFD package; however, the findings can be applied to any RANS solver.

Power control of the engine operating on the fixed pitch propeller

The analysis of operational and constructive methods for changing the power of the main engine working on a fixed pitch propeller has been carried out. To purposefully change the operating mode of the main engine, additional (special) jet action of water on the propeller blades of a fixed pitch can be used. The physical effect of supplying additional water to the blades and its effect on the effective power of the main engine is explained. The mutual arrangement of the propeller load curves of the characteristic modes of the engine when additional water is supplied to the blades is analysed. The additional modes of operation of the main engine, implemented with the help of an additional jet effect, are determined. Purposeful change in power consumption at a constant speed prevents possible overloading of the main engine in case of deterioration of operating conditions. Of further interest is the assessment of the thermal and mechanical tension of the main engine operating in varying operating conditions.

ОСОБЕННОСТИ РЕАЛИЗАЦИИ ДОПОЛНИТЕЛЬНОГО СТРУЙНОГО ВОЗДЕЙСТВИЯ ВОДЫ НА ЛОПАСТИ ГРЕБНОГО ВИНТА ФИКСИРОВАННОГО ШАГА

Oughening the requirements of the international Convention for the prevention of the sea from vessels of 1973, with amendments, demands to reduce the environmental pollution, which can be achieved by maintaining the operational coefficient of energy efficiency of the vessel constant during the voyage. The behavior of the main engine with the fixed pitch propeller in the ship power plant is determined by the operating conditions of the vessel. The dependence of thermal load of the main engine on the operating conditions leads to increased pollution of the environment by fuel combustion products and increased operative ratio of energy efficiency. The control of the thermal and mechanical intensity of the main engine when it is working on a non-nominal screw characteristic, under its “weighting” or “relief", ensures the preservation of the required energy efficiency indicators when operating conditions change. There have been analyzed the methods of implementing the system of additional water jet impact supplied through the slot nozzle of the blade on the propeller to control the thermal and mechanical intensity of the main engine, regardless of the influence of external operating conditions. The design factors dependent on the type of the helical-steering complex of the vessel and affecting the method of liquid supply to the slotted nozzle of the blade have been analyzed. The analysis of the design features of modern fixed pitch propellers, methods of making screw propellers has been given. The main criteria for the system have been determined in order to minimize the negative impact on the propeller system and to lower the useful effect of controlled response on heat load of the main engine. The proposed design of the system of liquid supply to the slotted nozzles of propeller blades is characterized by minimal impact on the propeller unit.

Propeller Selection by Means of Pareto Optimal Sets Applied to Flight Performance

Selection process of the propeller for short take-off and landing (STOL) category aircraft is described. The aim is to achieve the highest possible performance with fixed propeller. The requirements are following: high maximal horizontal and cruise speeds, short take-off, high rate of climb and fixed propeller. These requirements are contradictory and so Pareto sets were used in order to find the optimal propeller. The method is applied for a family of geometrically similar propellers that are suitable for 73.5 kW (100 hp) piston engine designed for ultralight category aircraft with maximal take-off weight 472.5 kg. The propellers have from two to eight blades, blade angle settings from 15° to 40° and diameter from 1.1m to 2.65m. Pareto frontier is designed for each couple of parameters and the optimal propeller is selected according to these results. For comparison, the optimal propeller selection from the propeller family by means of a standard single-optimal process based on the speed power coefficient cs is also used. Using of Pareto sets leads to considerable performance increase for the set of contradictory requirements. So, high performance power system with low price (fixed pitch propeller) for STOL category aircraft can be designed. The described method can be used for the propeller optimization in similar cases.

An Energy Efficiency Optimization Method for Fixed Pitch Propeller Electric Aircraft Propulsion Systems

As a key component of electric aircrafts, electric propulsion systems provide sufficient thrust for electric aircrafts. By improving its efficiency, the power consumed by the electric propulsion system can be reduced. Therefore, the maximum range of electric aircrafts, which is limited by the energy density of batteries, can be further increased. Upon investigating the power demand and the energy consumption of the electric propulsion system in each flight profile phase of fixed pitch propellers electric aircrafts, this paper proposes a novel energy efficiency optimization method tailored for fixed pitch propeller electric aircrafts by minimizing the total energy consumption of one flight over the maximum efficiency of the propeller. The proposed method is adopted to the design of a fixed pitch propeller electric aircraft. Experimental results suggest that the tested fixed propeller electric aircraft designed can achieve better energy efficiency while reducing energy consumption by more than 10%.

Flight control and flight experiments of a tilt-propeller VTOL UAV

The purpose of this work is to present a study on the stability and control of an unmanned, fixed wing, vertical take-off and landing aerial vehicle. This airplane is driven by a fixed-pitch tilt-propeller system with the capability of vertical take-off and landing as well as conventional flight. The novelty of the vehicle is the use of a fixed-pitch propeller system instead of variable-pitch tilt-rotors. There are three flight modes: vertical, transitional and conventional flight modes. Each flight mode has different dynamic characteristics. Therefore, these modes each need dedicated flight control methods. In this paper, the equations of motion are generated by modelling the aerodynamic and propulsion forces and moments. After performing trim condition calculations, longitudinal stability characteristics are investigated for each flight mode. The control methods are described for vertical, transitional and conventional flight modes. Stability augmentation systems, which consist of proportional and proportional/integral controller, are applied. A number of flight tests, including vertical, transitional and conventional flights, have been successfully performed with a prototype aircraft.

A method to improve the efficiency of an electric aircraft propulsion system

An electric aircraft propulsion system utilizes a high efficiency motor to generate thrust for electric aircraft. However, it can be challenging to maintain high efficiency for the fixed pitch propeller, which is commonly used in electric aircraft, through all phases of the flight. This paper investigates the power demands of the electric aircraft during the climb and the cruise phases according to the flight profile, and presents a model to estimate the energy consumption per flight. Simulation results suggest that the efficiency in the climb and the cruise phases can affect the energy consumption of an electric aircraft. Efficiency during the climb phase can have a significant effect on the capacity of the electric aircraft propulsion system. Based on the aforementioned results, this paper proposes a novel approach to achieve high efficiency, in which the optimal efficiency points of the electric aircraft propulsion system in the climb and the cruise phases can be obtained by solving an optimization problem with minimizing the energy consumption per flight as the object function and under the constraints that the climb and cruise phases must be successful. For testing purposes, the proposed method is adopted to the design of the electric aircraft propulsion system on a specific two-seater electric aircraft. Experimental results obtained from real flights suggest that the proposed method can reduce the energy consumption of the electric aircraft by over 10%, while reducing the capacity demand for the electric aircraft propulsion system.

Efficient Aerial–Aquatic Locomotion With a Single Propulsion System

Aerial–aquatic locomotion would allow a broad array of tasks in robot-enabled environmental monitoring or disaster management. One of the most significant challenges of aerial–aquatic locomotion in mobile robots is finding a propulsion system that is capable of working effectively in both fluids and transitioning between them. The large differences in the density and viscosity of air compared to water means that a single direct propulsion system without adaptability will be inefficient in at least one medium. This paper examines multimodal propeller propulsion using computational tools validated against experimental data. Based on this analysis, we present a novel gearbox enabling an aerial propulsion system to operate efficiently underwater. This is achieved with minimal complexity using a single fixed pitch propeller system, which can change gear underwater by reversing the drive motor, but with the gearing arranged to leave the propeller direction unchanged. This system is then integrated into a small robot, and flights in air and locomotion underwater are demonstrated.