Optimal Propeller Research Articles

Integrated lifting line/surface panel method for optimal propeller design with consideration of hub effect

An optimal marine propeller design method is proposed, which integrates the lifting line and surface panel method and is characterized by the use of the surface panel method to take the hub effect into consideration. By developing an integrated approach instead of an iterative method for the calculation of the interaction between the hub and the designed blades, the hub effects on the optimal circulation can be accounted for throughout the theoretical design procedure. This new integrated method provides a fast and accurate enough method to model the straight forward hub surface, in the optimal propeller design. A systematic design procedure from the basic design inputs to the blade geometry determination is performed and the designed propellers are validated by the surface panel method and the RANS method. The design and analysis cases are considered by different approaches with comparison and validation. And a comparative study including different hub geometries is also performed to reveal the mechanism of the hub effect on the distributions of the propeller optimal loads.

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.

Effects of Propeller Slipstream of Distributed Electric Propulsion on the Wing-Flap System

The studies are aimed at investigating the mechanism to ensure the high lift by installing propellers in front of the wing and using interference effects. The model of the wing section of a regional STOL aircraft with DEPSis considered. The wing section is equipped with a trailing edge device (Fowler flap) and DEPS consisting of motors with propellers. Parametric and experimental studies of the interaction between DEPS propellers and the regional STOL aircraft wing-flap system were carried out. The development and verification of aerodynamic calculation method for the wing section at low Reynolds numbers were performed. The comparison with the wind tunnel test data obtained at TSAGI was made. It was found that: - for fixed power of propellers there is an optimal propeller diameter ensuring maximum increase in the wing section lift; - at low thrust the total lift weakly depends on DEPS inclination angle.

Geometric constraints and optimization in externally driven propulsion.

Micro/nanomachines capable of propulsion through fluidic environments provide diverse opportunities in important biomedical applications. In this paper, we present a theoretical study on micromotors steered through liquid by an external rotating magnetic field. A purely geometric tight upper bound on the propulsion speed normalized with field frequency, known as propulsion efficiency, δ, for an arbitrarily shaped object is derived. Using this bound, we estimate the maximum propulsion efficiency of previously reported random magnetic aggregates. We introduce a complementary definition of the propulsion efficiency, δ*, that ranks propellers according to their maximal speed in body lengths per unit time and that appears to be preferable over the standard definition in a search for fastest machines. Using a bead-based hydrodynamic model combined with genetic algorithms, we determine that δ*-optimal propeller deviates strongly from the bioinspired slim helix and has a surprising chubby skew-symmetric shape. It is also shown that optimized propellers with preprogrammed shape are substantially more efficient than random magnetic aggregates. We anticipate that the results of the present study will provide guidance toward prospective experimental design of more efficient magnetic micro/nanomachines.

An Experimental Study to Investigate the Effect of the Angle of Attack on VToL UAV Propellers

Abstract Popularity of Unmanned Aerial Vehicles (UAVs) is continuously increasing for scientists as UAVs allow observation of large areas of land surfaces economically and swiftly when compared to traditional methods. And today the importance of UAVs is also increasing for civil applications such as transporting, agricultural spraying etc. These kind of civil applications are expected to require more power and different propeller geometries to provide higher payload capacities. In this context, aerial vehicle’s propeller size and pitch are important parameters in order to obtain proper lifting capacity for Vertical Take-off and Landing (VToL) UAVs. There is a number of terms to define the propeller’s specifications such as diameter, pitch, disc area relation, bore, material type etc. These characteristics must be calculated to design the optimal propeller accordingly to match specific needs of aerial vehicle characteristics. It is very important that both angle of attack and diameter should properly be investigated to be able to choose optimal propeller. The effect of angle of attack dominates characteristics of the propellers and in turn, aerial vehicles. In this manner, this paper focuses on the angle of attack of the propeller and propeller length as these variables have a huge effect on power consumption and lifting capacity. The effect of angle of attack that dominates characteristics of propellers and lifting capacity of aerial vehicles was investigated. Experiment results are presented for comparison of the propellers performance and outcomes were explained using charts.

Analysis Effect of Duct Length– Nozzle Diameter Ratio and Tip Clearance Variation on the Performance of K-Series Propeller

One type of ship propeller is a ducted propeller. Ducted propellers are propellers with sheath or duct that can increase thrust on the propeller and useful for directing the flow of water that will pass through the Propeller. In addition to improving thrust, ducted propellers can also increase torque compared with no duct. The basic theory of momentum for this ducted propeller operation has been used by Horn (1940). In order for the efficiency of the thrust to be of good value, the volume of water passing through the propeller should be as large as possible, with the smallest possible flow velocity. The most important components of ducted propeller are Ld / D and tip clearance. Ld / D is a coefficient comparison between the length of the casing / duct and the diameter of the duct, while the tip clearance is the distance between the tip of the propeller with an inner diameter of the duct. Both components are discussed in this study. The purpose of this research is to know the performance of propeller after given variation on Ld / D and tip clearance. The method used for propeller analysis is Computational Fluid Dynamic (CFD). Based on simulation result, the most optimal propeller performance is ducted propeller with Ld / D = 0.5 and tip clearance 40 mm

KAJIAN TEORITIK PENGARUH GEOMETRI DAN BENTUK SUDU TERHADAP UNJUK KERJA TURBIN PROPELLER

Abstract Electrical energy is one of the primary needs of Indonesian society that continues to increase. However, until now most of the electricity needs are still supplied by fossil fuel power plants. The fossil energy dependence affects the high cost of distributing electricity to remote areas. The picohydro power plant using propeller turbines is one solution for remote areas. The purpose of this paper is to conduct a theoretical study to obtain optimal propeller blade design with relatively easy design method. Based on the study results obtained geometry and design of turbine propeller that can produce efficiency 73,9% with head water 1,75 m and flowrate 64 l / s. While the propeller turbine design is the diameter of the turbine 200 mm the number of blades 5, and the inlet runner tip 65 °.

Simplified propeller analysis and design including effects of stall

ABSTRACTA simplified method to analyse propellers based on vortex theory is presented. Small-angle approximations are implemented to eliminate the need for iteration in the determination of the induced angle-of-attack. A stall model is developed and combined with analytic relations describing the blade aerofoil characteristics, eliminating the need for look-up tables of aerofoil behaviour. The method is also extended to serve as an optimal propeller design tool. Comparisons of the approach with experiment are presented for validation as an analysis tool. Use of the theory as a design tool is also demonstrated through contrast with an existing blade design methodology.

Variational Approach to the Problem of the Optimal Propeller Design

The aim of this paper is to evaluate the theoretical efficiency of optimal propellers by means of a variational approach; non classical propellers are included in the analysis. A solution to the optimum rotor problem, in the context of propeller vortex theory, was given by Goldstein in 1929; in this paper, a variational formulation of the optimum rotor problem is proposed. The formulation consists into finding a class of functions (the circulation along the blade axis) for which the thrust and drag momentum functionals are well defined; in this class, the functional is proved to be strictly convex and, thus, the global minimum exists and is unique. Some configurations are analysed using the Ritz method: classical straight blade, parabolic blade, elliptical blade; single and multiple blade propellers are compared.

Thrust generation by a heaving flexible foil: Resonance, nonlinearities, and optimality

Flexibility of marine animal fins has been thought to enhance swimming performance. However, despite numerous experimental and numerical studies on flapping flexible foils, there is still no clear understanding of the effect of flexibility and flapping amplitude on thrust generation and swimming efficiency. Here, to address this question, we combine experiments on a model system and a weakly nonlinear analysis. Experiments consist in immersing a flexible rectangular plate in a uniform flow and forcing this plate into a heaving motion at its leading edge. A complementary theoretical model is developed assuming a two-dimensional inviscid problem. In this model, nonlinear effects are taken into account by considering a transverse resistive drag. Under these hypotheses, a modal decomposition of the system motion allows us to predict the plate response amplitude and the generated thrust, as a function of the forcing amplitude and frequency. We show that this model can correctly predict the experimental data on plate kinematic response and thrust generation, as well as other data found in the literature. We also discuss the question of efficiency in the context of bio-inspired propulsion. Using the proposed model, we show that the optimal propeller for a given thrust and a given swimming speed is achieved when the actuating frequency is tuned to a resonance of the system, and when the optimal forcing amplitude scales as the square root of the required thrust.

Design and testing of a propeller for a two-seater aircraft powered by fuel cells

This article deals with the design, manufacturing, and testing of a propeller for a general aviation aircraft fuelled by hydrogen. The feasibility of the ENFICA-FC project depended on several key-enabling technologies. In order to minimize the power required from both the batteries and the fuel cell, a highly efficient electrical propulsion system was required, in which all the components would need to yield the highest possible efficiency. The choice of the propeller for this specific aircraft was more difficult, above all because the electric motor was limited as to the torque it could handle. In addition, the propeller would also have to provide the necessary airflow for the motor, electronics, and fuel cell cooling to ensure that the temperature did not exceed the limits imposed by the manufacturer. Although a designer may be aided by modern numerical design and analysis programmes to optimize propellers, structural and manufacturing constraints can influence the final choices. Finally, the calculated performance would always have to be validated with experimental tests. An optimal propeller has been designed and manufactured to be installed on the Rapid 200 FC aeroplane. Static tests on the manufactured two-blade propeller were performed by means of a static test facility. Specific tests have also been performed to check the efficiency of the propeller when installation effects (blockage and scrubbing drag effects) are included and to verify the real efficiency of the propulsion and cooling systems, with the propeller installed in the complete converted aircraft. A good agreement between the theoretical and experimental data was obtained.

Air Cooling of a Two-Seater Fuel Cell–Powered Aircraft: Dynamic Modeling and Comparison with Experimental Data

The application of fuel cell (FC) technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise reduction. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission (EC) funded project Environmentally Friendly Inter-City Aircraft Powered by Fuel Cells (ENFICA-FC). The main objective of the ENFICA-FC project was to develop and validate the use of a fuel cell-based power system for the propulsion of more-electric/all-electric aircraft. The fuel cell system was installed in the light sport aircraft Rapid 200, which was flight and performance tested. One of the key items under investigation is the simulation of the cooling system and the evaluation of fuel cell temperature. The polymer electrolyte membrane fuel cell (PEMFC) is considered to be the best candidate for the fuel cell vehicle because it has high power density, solid membrane electrolyte, and as it operates at low temperatures, it has a fast start-up. However, to generate a reliable and efficient power response and to prevent membrane degradation or damage with hydrogen and oxygen depletion, a sophisticated control technique becomes vitally important. In particular, as the ionic conduction of the polymeric membrane is a function of its degree of humidification, the stack temperature has to be carefully controlled to avoid phenomena of water evaporation, causing an increase of ohmic drop and a decrease of stack performances. The output voltage and hence the power of the fuel cell system is affected considerably by the change of the stack temperature. A simplified fluid-dynamic model has been developed and validated by computational fluid dynamics (CFD) analysis and it is used to compute the air flow to the fuel cell heat-exchanger inlet. Propeller effects are included referring to an optimal propeller specifically designed for the ENFICA-FC project. A mathematical model of the fuel cell system dynamics coupled with the fluid-dynamic model was studied in detail and experimentally validated during two flight tests of the Rapid 200-FC.

Engineering Method for Air-Cooling Design of Two-Seat Propeller-Driven Aircraft Powered by Fuel Cells

The application of fuel-cell technology to aircraft propulsion and/or energy supply is becoming of great interest for undoubted advantages in terms of pollution emissions and noise, features particularly important for commuter airplanes that usually take off and land from and in urban areas. The conversion of conventional aircraft into more/all-electric one tends to be based on the installation of such innovative systems. A better understanding of problems related to fuel cells applied to aeronautics is sought by the European Commission funded project environmentally friendly intercity aircraft powered by fuel cells ENFICA-FC. The main objective of the ENFICA-FC project is to develop and to validate the use of a fuel-cell based power system for propulsion of an all-electric aircraft. The fuel-cell system will be installed in a light sport aircraft Rapid 200 that will be flown and performance tested as a proof of functionality and future applicability. Specific aspects have to be investigated in the onboard installation of the innovative system and new design indications have to be pointed out in order to fulfill the conversion. One of the key items under investigation is the simulation of existing cooling system and the evaluation of motor and fuel-cell temperature; the temperature has to be maintained within the limits established by manufacturers of critical systems during all likely operating conditions as indicated by aeronautic regulations for general aviation. The computational problem addressed in this paper is the numerical computational fluid dynamics CFD simulation of the existing air-cooling system that satisfies air request for cooling and venting. An engineering model has been developed and it is used to support air inlet and outlet design. The flow is reasonably approximated by a potential flow plus boundary layer; hence, total upstream pressure losses are neglected except for those within the thin boundary layer. Pressure recovery of incoming cooling air and pressure coefficient distribution have been studied by using VSAERO panel code, and the optimal position of cooling and venting intakes is defined according to aerodynamic results. Propeller effects are included by referring to an optimal propeller specifically designed for the ENFICA-FC project. Propeller slip-stream wake is modeled by an actuator disk plus a swirl membrane and used to study the problem of motor, electronic, and fuel cells' cooling during takeoff.

Optimization of Propeller Based Propulsion System

Propeller design is a complex task that involves a variety of disciplines such as: aerodynamics, structural analysis, and acoustics. A new method of designing an optimal propeller which is based on a MDO (Multidisciplinary Design Optimization) approach is presented. By combining various analysis tools with an optimization tool, a powerful and flexible design method is obtained. During the design process three different optimization schemes are used, leading the design to its optimal goal. This new method is applied for the design of a propeller for an Ultralight aircraft. Several optional designs for different design goals are presented. The results of the new method are compared with results of the classical design method, based on Betz's condition, which considers only the aerodynamic performance of the propeller. The importance of addressing the characteristics of the entire air-vehicle, its aerodynamic characteristics and its propulsion system (engine, gear box, etc.), rather than only the isolated propeller, is emphasized.

A Numerical Study on Jet-Stream Propulsion of Oscillating Bodies

A Computational Fluid Dynamics (CFD) study on the jet-stream propulsion of rigidily oscillating and undulating bodies has been undertaken, by the unsteady solutions to the two-dimensional incompressible Navier-Stokes equations in conservative form, which are discretized with the finite volume method, using the pseudo-compressibility technique. Computational validation confirmed that the present method was capable to reasonably predict highly unsteady flows of biological problems. Numerical study on an oscillating hydrofoil (NACA 0012) reveals that there exists a problem of optimal propeller efficiency in generating the jet-stream in wake, but within a narrow region of the Strouhal numbers. Further analysis on a tadpole-shaped object and a fish-like body swimming in realistic kinematics, shows that the kinematics effectively produces a jet-stream propulsion with much higher propulsive efficiency than that of achieved by the oscillating hydrofoil. Investigation of Reynolds number effect for the undulatory swimming indicates that the propeller efficiency increases with increasing Reynolds number with no Re ceiling in generating the jet-stream.

An optimum screw propeller with endplates

The design of an optimal screw propeller model having endplates at the tips of its blades is discussed. The interaction of blades and endplates is taken into account and the determination of circulation around these lifting surfaces is based on linear optimization theory.

Effect Of Stern Tunnel Height On PropulsiveEfficiency Of Inland Vessels

The paper presents results of an analysis of how the stern tunnel height affects the propulsive efficiency of an inland vessel. The study is concerned with a typical configuration of one pusher plus two dumb barges. For each tunnel form and predefined design requirements an optimal propeller type was selected. A mathematical model was used to account for hydrodynamic interactions within the propulsive system. The model is capable of determining service parameters of the propeller with account of the hull and the waterway bed interactions. In particular, the effect of the waterway depth on the propulsive efficiency was determined.