Propeller Power Research Articles

Optimization techniques for the design of crescent-shaped hard sails for wind-assisted ship propulsion

Wind-assisted ship propulsion is one of the most promising technologies to achieve net zero emission in ship operations by 2050 due to its reliance on a fully renewable energy source. Hard sails with crescent profiles have been shown to potentially provide a greater benefit than symmetric sails in recent studies. In order to justify their application, it is necessary to create and adopt a specific design that guarantees a reduction in the engine load over the whole operational range of encounter angles. The current study provides a systematic approach to obtain such a design based on two techniques, one aiming to maximum sail thrust, the other to minimize propeller power. Surrogate models based on validated CFD simulations are adopted for optimization, and the most efficient design is found as an average over all the possible encounter angles. It was shown that the thrust maximized approach increased the average thrust generated by sail up to 12.3%, and the propeller power minimized approach improved the effectiveness of the sails up to 22% in terms of percent power reduction. It was also confirmed that crescent-shaped airfoils generally outperform symmetric airfoils in the considered conditions.

Analysis of Propeller Selection for Unmanned Aircraft

Unmanned aircraft are usually used to perform missions, for example surveillance missions. This mission is not always carried out in a suitable location. Researchers must ensure that the aircraft can take off properly. For this reason, runway distance greatly affects the performance of the aircraft. The aircraft can fail to take off due to the lack of thrust generated by the propeller. The propeller diameter size of each unmanned aircraft can differ from one another and this difference in propeller diameter causes a difference in thrust force. Therefore, it is very important to determine the right propeller diameter to be used on an unmanned aircraft that is adjusted to the runway distance. This propeller selection analysis is carried out using experimental methods, which is tool testing and simulation with Propeller Power Calculator software. The results of this study can be seen that a propeller with a larger diameter will produce a greater thrust force. The size of the diameter and pitch and the number of blades of a propeller can also affect the amount of thrust generated. This will be a consideration for choosing a propeller to be used on an unmanned aircraft. So that the selected propeller can be used optimally by reviewing the amount of thrust that is influenced by the amount of diameter.

Effects of surface morphology on the performance of water-lubricated thrust bearings

Purpose As the crucial support component of the propeller power system, the reliability of the operation of submersible pumps is influenced by the lubrication performance of water-lubricated thrust bearings. When the water-lubricated thrust bearings are under start-stop or heavy load conditions, the effect of surface morphology is crucial as the mixed lubrication regime is encountered. This paper aims to develop one mixed lubrication model for the water-lubricated thrust bearings to predict the effects of surface skewness, kurtosis and roughness orientation on the loading carrying capacity and tribological behavior. Design/methodology/approach This paper developed one improved mixed lubrication model specifically for the water-lubricated thrust bearing system. In this model, the hydrodynamic model was improved by using the height of the rough surface and its probability density function, combined with the average flow model. The asperity contact model was improved by using the equation for the Pearson system of frequency curves to characterize the non-Gaussian aspect of surface roughness distribution. Findings According to the results, negative skewness, large kurtosis and lateral surface pattern can improve the tribological performance of water-lubricated thrust bearings. Optimizing the surface morphology is a reasonable design method that can improve the performance of water-lubricated thrust bearings. Originality/value In this paper, one mixed lubrication model specifically for the water-lubricated thrust bearing with the effect of surface roughness into consideration was developed. Based on the developed model, the effect of surface morphology on tribological behavior can be evaluated. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2023-0247/

Research on transition corridor of distributed tilting power configuration

For a distributed tilt-power configuration aircraft, the transition corridor was studied based on limited conditions such as wing lift characteristics and propeller power requirement. By establishing the dynamic model of each component and balancing according to the balance equation, the boundary of the transition corridor of distributed tilting dynamic configuration is determined. The results show that the minimum forward flight speed required for a low Angle of attack is less than that for a high Angle of attack; the wing lift characteristic high-speed boundary and the propeller power limit boundary together form the high-speed boundary of the transition corridor.

Analysis of noise sources in the cabin of a passenger aircraft and methods for combating them

This paper examined the problem of noise in the aircraft cabin and ways to solve it. Through observations, the following causes of noise were identified: the power plant (acoustic and mechanical vibrations, turbulent boundary layer and others), the location of the engine relative to the airframe, the noise of the propeller (if it is a propeller power plant), the propeller of the power plant itself, the air conditioning system, and so on the same operating device in the cabin. There is a comprehensive way to solve the problem of noise in the aircraft cabin: for aircraft with turbojet engines, measures aimed at changing the design and use of sound- absorbing materials can be effective. For a turboprop aircraft, it is necessary to create low-noise propellers and synchronize the rotation of the propellers. For air conditioning elements, reducing duct and exhaust velocities allows for satisfactory acoustic performance of these sources. The reduction in “cabin noise” is achieved by changing the manufacturing technology of various noisy units. It should be emphasized that the possibility of reduction in the cabin and the aircraft is, in principle, laid down when designing the units and the aircraft as a whole. It is worth noting sound insulation, vibration insulation, as well as the rational location of noisy units, including the power plant, relative to the passenger cabin of the aircraft. From the study on sound insulation, we conclude that it is best to use 2 sound insulation options. Reducing noise is a feasible task and its greatest progress is achieved even at the design stage itself

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.

CFD Studies of Aircraft in Ground Effect for Saras MK II

Aerodynamic performance of an aircraft is affected when it is flying close to the ground, for example during take-off or landing. In order to estimate this effect, CFD simulations have been carried out over the SARAS Mk II aircraft configuration using an open source CFD solver with Spalart Allmaras (SA) turbulence model. The simulations were done for aircraft at different heights above the ground with flaps deployed and at different angles of attack with propeller power on. The take-off flap deflections of 15° and 20° and landing flap deflections of 30° and 35° were considered for the simulations. Power effects were modelled by using actuator disc model available in SU2. From the simulations, it is observed that, for all flap configurations and at all angles of attack studied, flying close to ground increases the lift of the aircraft, reduces drag and pitching moment. The factors of increase/reduction are used by the design group for better estimation of aircraft performance.

Influence of differential longitudinal cyclic pitch on flight dynamics of coaxial compound helicopter

The Differential Longitudinal Cyclic Pitch (DLCP) in coaxial compound helicopter is found to be useful in mitigating low-speed rotor interactions and improving flight performance. The complex mutual interaction is simulated by a revised rotor aerodynamics model, where an improved Blade Element Momentum Theory (BEMT) is proposed. Comparisons with the rotor inflow distributions and aircraft trim results from literature validate the accuracy of the model. Then, the influence of the DLCP on the flight dynamics of the aircraft is analysed. The trim characteristics indicate that a negative DLCP can reduce collective and differential collective inputs in low speed forward flight, and the negative longitudinal gradient is alleviated. Moreover, a moderate DLCP can reduce the rotor and total power consumption by 4.68% and 2.9%, respectively. As DLCP further increases, the increased propeller power and unbalanced thrust allocation offset the improvement. In high-speed flight, DLCP does not improve the performance except for extra lateral and heading stick displacements. In addition, the tip clearance is degraded throughout the speed envelope due to the differential pitching moment and the higher thrust from the lower rotor. Meanwhile, the changed rotor efficiency and induced velocity alter low-speed dynamic stability and controllability. The pitch and roll subsidences are slightly degraded with the DLCP, while the heave subsidence, dutch roll and phugoid modes are improved. Lastly, the on-axis controllability, including collective, differential collective pitch, longitudinal and lateral cyclic pitches, varies with DLCP due to its effect on rotor efficiency and inflow distribution. In conclusion, a reasonable DLCP is recommended to adjust the rotor interaction and improve aircraft performance, and further to alter the flight dynamics and aerodynamics of aircraft.

Towards predicting noise-power-distance curves for propeller and rotor powered aircraft

Propeller and rotor based propulsion systems are the dominating choice of power delivery system in the upcoming Urban Air Mobility market. Fully electric air-taxis (car sized vehicles with Vertical Take-off and Landing, VTOL, capabilities) concepts are using the benefits of the scalable properties of electric motors to distribute propulsor units all over the airframe. The large variety of concepts and configurations of these vehicles poses a serious issue in predicting noise generated on the ground. The need for a high-level model to aid in acoustic decision making is evident. Through the demonstrated methodology of computationally deriving Noise - Power - Distance curves for conventional turbo fan aircraft, this paper delivers the capability of dealing with propeller propulsion systems and the associated propeller tonal noise sources to generate the NPDs and therefore noise exposure maps. The aims can be broken down into two objectives: a) demonstrate the capabilities of the proposed propeller harmonics noise scaling laws to calculate noise variation from a baseline scenario and b) incorporate the scaling components into the larger capability of producing noise exposure contours, by the means of computationally deriving NPD curves for propeller powered aircraft. Preliminary NPD curves for General Aviation sized propeller power aircraft are generated and discussed.

Stochastic Drift Counteraction Optimal Control of a Fuel Cell-Powered Small Unmanned Aerial Vehicle

This paper investigates optimal power management of a fuel cell hybrid small unmanned aerial vehicle (sUAV) from the perspective of endurance (time of flight) maximization in a stochastic environment. Stochastic drift counteraction optimal control is exploited to obtain an optimal policy for power management that coordinates the operation of the fuel cell and battery to maximize the expected flight time while accounting for the limits on the rate of change of fuel cell power output and the orientation dependence of fuel cell efficiency. The proposed power management strategy accounts for known statistics in transitions of propeller power and climb angle during the mission, but does not require the exact preview of their time histories. The optimal control policy is generated offline using value iterations implemented in Cython, demonstrating an order of magnitude speedup as compared to MATLAB. It is also shown that the value iterations can be further sped up using a discount factor, but at the cost of decreased performance. Simulation results for a 1.5 kg sUAV are reported that illustrate the optimal coordination between the fuel cell and the battery during aircraft maneuvers, including a turnpike in the battery state of charge (SOC) trajectory. As the fuel cell is not able to support fast changes in power output, the optimal policy is shown to charge the battery to the turnpike value if starting from a low initial SOC value. If starting from a high SOC value, the battery energy is used till a turnpike value of the SOC is reached with further discharge delayed to later in the flight. For the specific scenarios and simulated sUAV parameters considered, the results indicate the capability of up to 2.7 h of flight time.

Development and quality control method of variable torque propeller for wind tunnel power simulation

In order to study the comprehensive influence of propeller power and sea surface effect of a seaplane, a composite material variable torque propeller for wind tunnel power simulation was developed. In order to make the quality of wind tunnel test data meet the standard of engineering application and control the quality of propeller products, a quality control method was developed to control the quality of design, checking, manufacturing, verification and operation of the propeller in all stages. In this paper, the research and development process and quality control method of the propeller, tests and the detection results, as well as the application test are described in detail. The results show that the quality control method described in this paper can be used to design and manufacture the propeller products which match the technical indicators, and the power simulation system composed of the propeller can exert slipstream influence on a certain seaplane under various working conditions, so as to meet the requirements of the study on the comprehensive influence of propeller power and sea surface effect of the aircraft.

Influence of Propeller Location, Diameter, and Rotation Direction on Aerodynamic Efficiency

In this Paper, the integrated propeller–wing system design space is investigated to gain insight into the influence of propeller diameter, location, and rotation direction. To conduct this investigation, a methodology is developed that uses the propeller power required during steady-level flight as a metric for efficiency. Full mutual interaction between the propeller and wing are taken into account in the aerodynamic analysis. To ensure that the propeller is not operating off design, it is designed within an iterative trim loop. This approach is then used to investigate the theory that an inboard-up rotating propeller located at the wing tip is the most aerodynamically efficient configuration through the use of a test case. When considering the trimmed propeller power required, the trends for this case indicate that the optimal propeller for this planform is not an inboard-up rotating propeller at the wing tip, but instead is an inboard-down rotating propeller near the root of the wing.

Analytical Model for the Performance Curves of a Family of Propellers Based on Wind Tunnel Tests

Propeller aircraft performance is greatly influenced by the performance of the propeller it uses. Thus, proper selection of a propeller for a given aircraft design at the early stages of the design process is fundamental. During the design of a new aircraft, simple yet accurate performance models are required to properly optimize the design. Significant experimental performance data of low speed, small propellers is available. The main objective of this work is to create and validate an analytical model for the performance curves of a family of propellers tested at low Reynolds numbers, which can be used in selecting a propeller for a given existing aircraft design or during its design optimization process. This kind of propellers is more commonly used in Unmanned Aerial Vehicles (UAVs). The model is designed in MATLAB® using a variety of regression techniques, such as the Least Squares Method (LSQ), applied to experimental data acquired at University of Illinois at Urbana-Champaign (UIUC), for seventeen APC Thin Electric propellers, and at the Department of Aerospace Sciences (DCA) of University of Beira Interior (UBI), for ten more APC Thin Electric propellers. The analytical model predicts propeller power coefficient and propulsive efficiency accurately for the family of propellers tested and can also be used for the propellers with dimensions close to those used for its development. The propeller performance data obtained during the experimental tests are made available the community to further increase the documentation on propellers tested at low Reynolds numbers.
 Keywords: Propeller, Low Reynolds propeller performance, Propeller tests, Wind tunnel

Research on Simulation Method of Propeller Power in the Model Free-flight Test

Research on Simulation Method of Propeller Power in the Model Free-flight Test

THE EFFECT OF LEEWAY ANGLE ON THE PROPELLER PERFORMANCE

One of the aspects influencing the performance of wind assisted vessels is the effect of leeway (drift) angle on the propeller performance. It is known that due to leeway the delivered propeller power and propulsive efficiency can vary significantly from the straight sailing condition. This effect of leeway angle is studied using a combination of viscous flow calculations and captive model tests for one twin screw and three single screw vessels. It is observed that the changes in mean axial velocity and pre-swirl rotation in the wakefield due to a combination of leeway angle and propeller suction are sufficient to describe the trends observed in captive model tests. This knowledge is used in a proposed prediction method to model the changes in propeller thrust and torque due to leeway angle at the design stage. The prediction model combined with a fit of the average wake parameters for the studied vessel types is finally used the show the trends in propulsive efficiency and delivered propeller power at constant propeller rotation rate and ship speed for small leeway angles.

Research on Aerodynamic Shape Design Scheme of a Distributed Propeller Transport Aircraft and Its Slipstream Effect

With the continuous development and widespread attention of electric propulsion technology in traditional transportation fields such as automobiles and trains, the distributed propeller propulsion technology applied to electric or hybrid electric medium and small scale aircrafts has become a new topic in aviation research. This paper presents a preliminary design scheme of a distributed propeller electric propulsion transport aircraft firstly. Then, based on Reynolds average N-S equations, combined with the SA turbulence model, and replaced the real distributed propellers with simplified disk model, the aerodynamic characteristics of the aircraft with and without slipstream under the condition of low speed and high thrust at low altitude are analyzed. Finally, the effects of pressure distribution, pitching moment characteristics and wing flow on distributed propellers are studied in detailed. The results show that the lift and drag of the aircraft with slipstream are both larger than without slipstream and with slipstream effect, the pitching moment of the wing decreases, the pitching moment of the tail increases. When the tail is far away or completely inside the region of slipstream, the difference of pitching moment of the tail with and without slipstream is little, and the difference is obvious as the tail is only partially in the region of slipstream; When the diameter of distributed propellers is far larger than the wing thickness, more propeller power is used to shove air flow away from the surface area of the wing, and resulting in an insignificant increase in the coefficient of lift.

The Ducted Propeller Design and Hydrodynamic Performance Analysis

This paper aim at the integrated rudder propeller power transmission system which is specific to the towing and tugging ships rudder propeller system, presented an analyzing method with ducted propeller design. Analyzed the thrusttorqueefficiency and total pressure distribution law of blade in the condition of open water work of the propeller by means of finite element method. The numerical results and the flow details are concluded and compared with published experimental data, .Results displayed in good agreement with theoretical analysis results. Initially formed a whole process of design the rudder propeller from the initial ship type parameters to prediction of propeller under open water test condition, and had a certain reference value.

Design Method and Calibration of Moulinet

The formula for obtaining the absorption horsepower of a Moulinet was rewritten, and the physical meaning of the constant in the formula was clarified. Based on this study, the design method of the Moulinet and the calibration method of the Moulinet that was performed after manufacture were verified experimentally. Consequently, the following was clarified; (1) If the propeller power coefficient was taken to be the proportionality constant, the absorption horsepower of the Moulinet was proportional to the cube of the revolution speed, and the fifth power of the Moulinet diameter. (2) If the Moulinet design was geometrically similar to the standard dimensions of the Aviation Technical Research Center's type-6 Moulinet, the proportionality constant C1 given in the reference could be used, and the absorption horsepower of the Moulinet was proportional to the cube of the revolution speed, the cube of the Moulinet diameter, and the side projection area of the Moulinet. (3) The proportionality constant C1 was proportional to the propeller power coefficient CP.

Designing Method and Calibration of Moulinet

In this paper, the formula for obtaining the absorption horsepower of Moulinet was redrawn, and the physical meaning of the constant in the formula was clarified. Based on this study, it was verified experimentally about the designing method of Moulinet and the calibration method of Moulinet after manufacture. Consequently, the followings were clarified; (1) if the propeller power coefficient was taken to the proportionality constant, the absorption horsepower of Moulinet was proportional to the cube of the revolution, and the fifth power of the Moulinet diameter. (2) if it was Moulinet which carried out the similarity design geometrically with the standard size of Aviation Technical Research Center's type-6 Moulinet, the proportionality constant C1 given in the reference could be used, and the absorption horsepower of the Moulinet was proportional to the cube of the revolution, the cube of the Moulinet diameter, and the side projection area of the Moulinet. (3) the proportionality constant C1 was proportional to the propeller power coefficient CP.

Fuel-efficient rudder and propeller control allocation for marine craft: experiments with a model ship

We derived a control allocation algorithm for low-speed marine craft using propellers and rudders. Active use of rudders has advantages in a low-speed operation by decreasing the need for propeller power and fuel. However, at low speed, a rudder is effective only for positive thrust. This complicates the thrust allocation problem which can no longer be solved by convex quadratic programming. In fact, the existence of local minima introduces discontinuities in the commanded thruster signals even if the desired control force is continuous. Discontinuous signals cause excessive wear on the thruster system and must be avoided. This paper suggests an analytic, 2-norm optimal method that can ensure continuity of the solutions. Being analytic, however, its limitation is the capability of handling only configurations where one single thrust device is subject to sector constraints at a time. Experiments with a model ship illustrate the potential for fuel saving. For this particular vessel, the energy consumption was halved. An output feedback tracking control law with integral action was simultaneously derived and analyzed. Semiglobal ship controllers like this one rely on the yaw rate being bounded, and an admittedly conservative method for determining this upper bound was proposed.