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This paper reconciles the assessment of fan and propeller performance by deriving common metrics that describe their design and operational characteristics and applies them to real-world design examples. Historically, various applications with large differences in flight Mach number and thrust requirements have led to different design methodologies and performance descriptors for ducted and unducted propulsors, making direct comparisons between these propulsion concepts challenging until today. One of the limitations of conventional propeller design methods is the difficulty in isolating the aerodynamic performance of blade sections from the overall design concept. The overall efficiency is largely impacted by top-level design parameters, while the aerodynamic quality is determined by the shaping and spanwise stacking of blade profiles. In contrast, turbomachinery design focuses primarily on the efficiency of the compression process and their respective efficiency metrics. This paper addresses these issues by systematically breaking down propeller efficiency into contributions commonly used in turbomachinery design. By applying consistent methodologies, we thereby enable a fair and quantitative comparison of the potential performance benefit of each concept. Furthermore, using common performance metrics simplifies the design process, making it more accessible to less experienced designers and facilitating the exploration of alternative design approaches for unducted propulsors.

CFD method has the advantages of high forecast accuracy, wide applicability, strong stability of calculation results, and low cost, and nowadays it has been widely used in various fields. The CFD method has many advantages when applied to ship hydrodynamic performance analysis, specifically to ship hydrodynamic performance prediction, problem mechanism research, and performance optimization. Based on this, this paper utilizes the CFD method to carry out a model analysis of ship hydrodynamic performance. By analyzing the propeller efficiency, the reasoning force and torque of the double propeller in the symmetric case are decreased. However, the efficiency is improved by 1.4% compared with the asymmetric case, which shows that the method adopted in this paper can effectively improve the ship hydrodynamic force. Through the above research, we aim to provide a certain reference for the improvement of ship hydrodynamic performance.

In view of the low speed and instability of the flow between the two arms of the bracket in front of the propeller, the fairing is installed between the arms of the bracket taking example of compensating duct, in order to speed up the flow between the bracket arms and improve the flow quality. A four-propeller surface ship was studied and an integral mathematic model including hull, appendage and propellers was established. Using a RANS solver, its installation height, angle and airfoil is optimized. Then ship models with fairing and without fairing are calculated. The result shows that fairing improves propeller efficiency behind ship with 1.1% of the outer propeller and 1.6% of the inner propeller, which indicates that fairing helps improve the flow quality

The design task for distributed propulsion (DP) aircraft is more complex than conventional twin-engine designs due to the pronounced propeller wing interaction. DP concepts rely on a beneficial and robust interaction of propulsion and lifting surface. Additionally, a good DP design is optimised as a system such that each element is not optimised by itself (i.e. η prop and C L /C D ) , but with consideration of the close coupled interaction. The evaluation of such an interaction driven setup is scope of this work. Thrust and torque of a periodic co-rotating DP wing are measured simultaneously with airfoil coefficients. Thereby the influence of propeller on the wing and vice versa are identified. Two different sets of propeller geometries with a diameter of D = 0.6 m are studied. One propeller set is designed for minimum induced propeller loss (MIL). The second propeller set is designed to have a constant induced axial velocity over the radius (CIV). We shall compare how the different strategies perform in the DP system. The two element wing has a span of B = 2.4 m and a reference chord of c = 0.8 m, operating at Re = 2.1 × 10 6 . For this study, the propellers are pitched to meet a constant c T , J and Ma tip . The results focus on the system performance for the combined setup in take-off configuration. While the isolated propeller efficiency benefits from the integration in front of the wing by > Δ η prop = 12%, the system efficiency suffers from increased drag on the trailing wing that is roughly tripled over the clean wing. Depending on the propeller position relative to the wing, interaction losses can be minimised so that a system efficiency gain over the isolated wing and propeller of > Δ η sys = 4% is achieved.

This paper delves into the effects of a toroidal propeller’s geometrical characteristics on its thrust and efficiency. The focus is on three distinct numerical distributions: the outward inclination angle, the pitch angle, and the number of blades. The Reynolds-Averaged Navier–Stokes (RANS) method is employed to analyze the propeller’s open-water performance, taking into account cavitation flow, and a test bed was constructed to verify the rationality of CFD simulation. The findings reveal that the toroidal propeller’s efficiency and thrust coefficient initially increase with the outward inclination angle, followed by a decline; the angle of maximum efficiency is identified at 23.25°. A reduction in the pitch angle leads to a temporary rise in efficiency, which subsequently falls, accompanied by a continuous decrease in the thrust coefficient. The optimal selection angle should consider this to prevent negative thrust at lower advance coefficients, which could further impact overall efficiency. An increased number of blades elevates the thrust coefficient and reduces the force on each blade, yet has a minimal effect on efficiency. Additionally, the orthogonal test method was utilized to explore the interactions between these three parameters. The outcomes indicate that, in terms of final power, there is no significant interaction among the three parameters under investigation. However, notable interactions are observed between the pitch angle and the number of blades, the outward inclination angle and the pitch angle, and the outward inclination angle and the number of blades. Consequently, the study’s findings facilitate the selection of parameter combinations that yield higher efficiency or thrust coefficients.

The camber ratio of a propeller significantly affects its hydrodynamic performance. The camber ratio particularly affects the lift force generated by the propeller blades, which ultimately affects the propeller thrust and torque. In this study, effects of camber ratio variations are investigated by using a combined method of panel vortex method and blade element theory. The camber ratios considered in this study are as follows: 0% (0.00, original foil), 1.6% (0.016), 2.2% (0.022), and 2.8% (0.028). A larger camber ratio results in a more convex propeller blade surface. Calculation results show that the larger the camber ratio, the higher the thrust and torque coefficients. The camber ratio of 2.2% (0.022) gives the highest propeller efficiency of 58.5% at the advance coefficient J = 0.7.

The paper took one controllable pitch propeller as study model. Open water performance at different pitches were calculated based on FLUENT. On this basis, rotational speeds that match P/D = 1.5, 1.3, 1.15, 1.0 at 21kn were obtained according to characteristic curve of navigation. Propeller efficiency and pulsing pressure were carried out and compared at different matches. The result shows that pulsating pressure is both influenced by speed and pitch. It is non-linear relationship between pitch ratio and cavitation and efficiency and is inconsistent with the character of propulsion efficiency. Hence it brings adverse effect on pulsing pressure if the match of speed and pitch is selected only according to propulsion efficiency. The paper recommends comprehensive consideration about pulsing pressure and propulsion performance should be taken to choose match of speed and pitch at non-cavitation condition.

Motor-propeller matching plays a critical role in enhancing the efficiency of electric propulsion airplanes, especially for powered parafoil. This study firstly establishes models for the motor and propeller. A first-order DC motor model is implemented to characterize the motor properties, and a propeller model based on blade element momentum theory is utilized to analyse aerodynamic properties, with validation against experimental data. Secondly, two matching methods are developed. The graphical matching method visually obtains the matching points from the performance curve, and the surrogate model trained by the neural network directly compute the matching results. Finally, results from two matching methods are validated with the flight test data. Furthermore, the analysis reveals the motor-propeller efficiency of the tested powered parafoil system achieves less than 33%. Several suggestions are also proposed to improve the efficiency.

Following the United Nations 2030 Agenda to achieve a better and more sustainable future, there is an interest in new energy efficiency technologies to address emissions from international maritime shipping. A large portion of the available research focused on paints that reduce the fouling and friction of the hulls of these vessels, such as hydrophobic paints. Yet, research applied to propellers is smaller when compared to hulls. Covering the blade surface with hydrophobic paint behavior changes the drag of the propeller and, consequently, the hydrodynamic efficiency. However, covering a blade may adversely affect the flow in certain regions, reducing the propeller performance. This paper studies a practical application of the super-hydrophobic surface (SHS) pattern distribution on a marine propeller using the topology optimization method to determine regions where the application of surface treatment leads to improved propeller efficiency. The numerical method is developed to model the turbulent flow condition with the behavior of the boundary layer that imposes the low-friction/hydrophobicity effect to predict the performance of a coated propeller. To evaluate the proposed method, firstly, a fully covered blade is simulated for several hydrophobic conditions, and then the topology optimization is conducted. Despite the SHS behavior being simplified by adopting the slip length model, the obtained optimization results show the regions to be prioritized in order to maximize the hydrodynamic efficiency.

This study presents a practical optimization procedure that couples the NavCad power prediction tool and a nonlinear optimizer integrated into the Matlab environment. This developed model aims at selecting a propeller at the engine operating point with minimum fuel consumption for different ship speeds in calm water condition. The procedure takes into account both the efficiency of the propeller and the specific fuel consumption of the engine. It is focused on reducing fuel consumption for the expected operational profile of the ship, contributing to energy efficiency in a complementary way as ship routing does. This model assists the ship and propeller designers in selecting the main parameters of the geometry, the operating point of a fixed-pitch propeller from Wageningen B-series and to define the gearbox ratio by minimizing the fuel consumption of a container ship, rather than only maximizing the propeller efficiency. Optimized results of the performance of several marine propellers with different number of blades working at different cruising speeds are also presented for comparison, while verifying the strength, cavitation and noise issues for each simulated case.