Propeller Design Research Articles

Propeller Design for an Autonomous Underwater Vehicle by the Lifting-line Method based on OpenProp and CFD

Propeller Design for an Autonomous Underwater Vehicle by the Lifting-line Method based on OpenProp and CFD

Computational fluid dynamics (CFD) based propeller design improvement for high altitude long endurance (HALE) UAV

PurposeHigh Altitude Long Endurance Unmanned Aerial Vehicle (HALE UAV) driven by a hybrid power between battery and solar panel have attracted many researchers. The HALE UAV which develops at Bandung Institute of Technology has design requirements of a 63 kg MTOW with a cruise velocity of 22.1 m/s at an altitude of 60,000 ft propelled by two propellers. The main problems that arise with the propellers gained from the market are these propellers cannot operate properly at the cruise phase due to inadequate thrust and high drag value. This paper aims to design a propeller that solves those problems.Design/methodology/approachThe Larrabee method is used to design this propeller geometry with an output in the form of a chord and twist distribution. The CFD approach method is used to improve the design resulting from the Larrabee method.FindingsThis study shows that the inputted thrust value of the propeller designed using the Larrabee method is always higher than the thrust value resulting from the CFD simulation with a difference of around 20% so a design improvement process using CFD is required.Originality/valueThe analysis of propeller implementation in various mission profiles shows that this propeller can operate fully from climbing at sea level to cruising flight at an altitude of 60,000 ft. The same procedure can be applied in other HALE UAV cases to generate a propeller design with different objectives.

Design and Analysis of Marine Propeller

This paper presents a comparison between propellers varying in design to evaluate their performance and efficiency. A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of airfoil shape blade and fluid is accelerated behind the blades which generates two forces, one along the longitudinal direction of ship which is the axial force called thrust force and tangential force which produce the required torque. As propeller has great influence on the propulsive performance of ship, propeller design is important technology for energy saving in ship propulsion. Generally, alloy of aluminium or bronze material are used for manufacturing of marine propeller. The propeller is a complex geometry which requires high end modelling software. The solid model of propeller is developed in HydroComp PropCad 2005 and SolidWorks 2019 and a tetrahedral mesh is generated for this model using HYPER MESH and simulation is carried out using SolidWorks. By considering all the study and benefits this model helps to find the optimum propeller for defined objectives. Based on optimized parameters the propellers performance is calculated by the simulation of designed model.

Multifidelity Analysis of a Solo Propeller: Entropy Rise Using Vorticity Dynamics and Kinetic Energy Dissipation

Propellers for electric aviation are used in solo- and multirotor applications. Multifidelity analysis with reduced cycle time is crucial to explore several designs for energy minimization and range maximization. A low-fidelity design tool, py_BEM, is developed for design and analysis of a reverse-engineered solo 2-bladed propeller using blade-element momentum theory with physics enhancements including local Reynolds number effect, boundary-layer rotation, airfoil polar at large AoAs and stall delay. Spanwise properties from py_BEM are converted into 3D blade geometry using T-Blade3. S809 and NACA airfoil polar are utilized, obtained by XFOIL. Lift, drag, performance losses, wake analysis, comparison of 3D steady CFD with low fidelity tool, kinetic energy dissipation, entropy and exergy through irreversibility are analyzed. Spanwise thrust and torque comparison between low and high fidelity reveals the effect of blade rotation on the polar. Vorticity dynamics and boundary-vorticity flux methods describe the onset of flow separation and entropy rise. Various components of drag and loss are accounted. The entropy rise in the boundary layer and downstream propagation and mixing out with freestream are demonstrated qualitatively. Irreversibility is accounted downstream of the rotor using the second-law approach to understand the quality of available energy. The performance metrics are within 5% error for both fidelities.

Propeller–hull interaction beyond the propulsive factors—A case study on the performance of different propeller designs

The propulsive factors are critical for scaling of model-test data, and hence important for the final power prediction. When comparing different propulsion systems based on model-scale tests, differences in propulsive factors, and hence the propeller–hull interaction, are often not well understood. In this study the propeller–hull interaction is instead described and compared using CFD for three different propulsion systems, a tip-unloaded ice-classed propeller, an ice-classed propeller with conventional radial load distribution and a non ice-classed propeller with conventional radial load distribution. To post-process the results KT/KQ is evaluated for one blade around a revolution and complemented with radial distributions of the same measure. Both tip-unloaded blades and sharp leading edges suffer in-behind due to poor performance at low load. Open water performance dependency on Reynolds number reveals that ice-classed propellers are more negatively influenced by the low Reynolds numbers of self-propulsion tests. Further, it is noted that a more even radial load distribution favours a low thrust deduction factor. Since the propulsive factors to a large extent are influenced by scale-effects and also due to that their association to the observed hydrodynamics makes the commonly applied scaling procedure of them questionable, they are not considered representative for ship-scale power prediction.

A machine learning approach for propeller design and optimization: Part I

This paper introduces a machine learning approach for optimizing propellers. The method aims to improve the computational cost of optimization by reducing the number of evaluations required to find solutions. This is achieved by directing the search towards design clusters with good performance, i.e. high propulsive efficiency and low cavitation. Three types of clusters are expected. The first cluster constitutes designs with performance of interest, i.e. high efficiency and low cavitation. The second cluster constitutes designs with performance not of interest, i.e. low efficiency and high cavitation. The third cluster constitutes designs whose performance cannot be estimated with the Boundary Element Methods (BEM) that we use in this study. In simple cases with single objective optimization to maximize efficiency, these clusters can be identified a-priori with unsupervised classifiers provided that orthogonally independent parameters are used as demonstrated in this paper. For multi-objective constrained optimization, to maximize efficiency and minimize cavitation, for example, supervised classifiers may be required to learn the clusters. Classical design variables such as chordlength, pitch, skew, rake, thickness distribution and camber of hydrofoils cannot be used to identify these clusters because of multicollinearity. Thus, a new orthogonal parametric model is proposed where the parameters are directly derived from the propeller blade mesh. As the blade surface mesh is used as boundary conditions to solve the governing equations, the orthogonal parameters are expected to have a stronger correlation with performance predictions of BEM or Computational Fluid Dynamics (CFD) than classical design variables. We demonstrate that design clusters with good performance can be identified with few BEM evaluations. Furthermore, the method synergizes explainable supervised and unsupervised learning to advice search algorithms and quickly guide them to lucrative regions in the design space. However, reducing the cost of optimization results in a trade-off with completeness of the search; this is also investigated in this paper. The method is demonstrated on a simple fully wetted flow case of the benchmark Wageningen B-4 70 propeller with P/D=1.0, as the geometry and open-water curves are readily accessible allowing back of the envelope verification and validation of our results.

Flow Separation Evaluation on Tubercle Ship Propeller

Propeller design for ship propulsion is important based on efficiency and power output. Advanced propeller design has been proposed in recent research, such as the tubercle propeller. The modified propeller on the leading edge with a tubercle-like design has been improved. Moreover, some evaluation has been studied on the design and performance. In the present study, the tubercle design on the leading edge is evaluated, which focuses on the flow separation effect developed by the tubercle shape. A computational fluid dynamic (CFD) model is compared between the normal and tubercle leading edge. The flow total pressure, Reynold number velocity, and power surface acoustic are evaluated. The flow separation is generated in the leading edge due to the tubercle shape. Moreover, the tubercle shape reduces the total pressure at the propeller blade, especially at the edges. It also increases the Reynold number velocity at the surface due to the flow separation. However, the flow separation decreased the power acoustic surface, which means it lost some power on the propeller.

Exciting a cavitating tip vortex with synthetic inflow turbulence: A CFD analysis of vortex kinematics, dynamics and sound generation

Cavitating tip vortices are one of the main contributors to underwater radiated noise (URN). To predict URN and evaluate propeller designs, it is necessary to predict cavity dynamics. To this end, a tip vortex generated by an elliptical wing is simulated in wetted and cavitating conditions, using scale-resolving simulations. The vortex is excited by synthetic inflow turbulence with varying inflow turbulence intensities. Vortex kinematics and cavity dynamics are analysed, and validated against experiments and a semi-analytical model from literature. The far-field radiated noise is analysed using an acoustic analogy. Using a background noise correction, the sound due to inflow turbulence is removed, and the sound due to cavity dynamics is isolated. Based on the sound spectra, the main noise generating mechanisms are identified. Cavitating simulations predict an increase in far-field radiated noise of approximately 15 dB, while doubling the inflow turbulence intensity results in an increase of approximately 10 dB.

A machine learning approach for propeller design and optimization: Part II

We propose and analyse an optimization method that uses a machine learning approach to solve multi-objective, constrained propeller optimization problems. The method uses an online learning strategy where explainable supervised classifiers learn the location of the Pareto front and advise search strategies. The classifiers are trained with orthogonal features that capture geometric variation in radial distribution of pitch, skew, camber and chordlength. Based on orthogonal features, the classifiers predict whether or not a design lies on the Pareto front. If the design is predicted to lie on the Pareto front, the method verifies this with an evaluation. If the design is predicted to not lie on the Pareto front with a high confidence level, then the design is ignored. This skipped evaluation reduces the computational effort of optimization. The method is demonstrated on a cavitating, unsteady flow case of the Wageningen B-4 70 propeller with P/D = 1.0 operating in the Seiun-Maru wake. Compared to the classical Non-dominated Sorting Genetic Algorithm — III (NSGA-III) the optimization method is able to reduce 30% of evaluations per generation while reproducing a comparable Pareto front. Trade-offs between suction side, pressure side, tip-vortex cavitation and efficiency are identified from the Pareto front. The non-elitist NSGA-III search algorithm in conjunction with the explainable supervised classifiers also find very diverse solutions. Among the solutions, a design with no pressure side cavitation, low suction side cavitation and reasonable tip-vortex cavitation is found.

A marine propeller design method based on two-fidelity data levels

A Simulation Based Design Optimization method for marine propellers design using a two-fidelity levels metamodel for global design space exploration and optimization is presented. Response surfaces are built using the co-Kriging approximation, i.e. a multi-output Gaussian process that combines large low-fidelity dataset with few, costly, high-fidelity data. The method is applied for the hydrodynamic shape optimization of the E779A propeller using, as fidelity levels, two different physical models for the propeller performances prediction, namely an inviscid, potential based Boundary Element Method (low-fidelity) and a viscous, finite volume RANS solver (high-fidelity). Results demonstrate the feasibility of multi-objective, constrained, design procedures, like those involving marine propellers, using these multi-fidelity response surfaces. At the same time, the need of good correlations between low- and high-fidelity data feeding the response surfaces is highlighted as a requisite for robust and reliable predictions using these approximated methods.

Predicting cavitating propeller noise in off-design conditions using scale-resolving CFD simulations

There is increasing awareness about the harmful impact of underwater radiated noise of shipping on the marine environment, with propeller cavitation being a major contributor thereof. In order to allow low-noise propeller design, reliable and validated numerical tools are necessary. The combined use of viscous computational fluid dynamics (CFD) and Ffowcs Williams–Hawkings acoustic analogy has long been suggested as a potential frontrunner that could address this need. However, few studies presented in the open literature have shown detailed validation focused on farfield radiated noise of propellers in cavitating conditions. Present work aims to address this by applying the methodology to two thrusters operating in off-design conditions and tested at model scale. Flow is computed using scale-resolving CFD simulations and a mass-transfer cavitation model. This allows for part of the turbulence spectrum and cavitation dynamics to be resolved. It is shown that peak sound pressure levels, corresponding to the low-frequency underwater radiated noise source, may be predicted to within 5 dB of experimental results. In addition, key features of the noise spectra, such as centre frequency of the peak broadband noise level and decay slope, are also well represented in the computations. The results are supplemented by analysis of the numerical signal-to-noise ratio.

Multi-objective optimization design method of marine propeller based on fluid-structure interaction

To improve the quality and efficiency of propeller design and obtain the best design scheme of the propeller, an integrated automatic optimization design method of propeller is proposed by combining Fluid-Structure Interaction (FSI), Design of Experiment (DoE), and Non-dominated Sorting Genetic Algorithm II (NSGA-II). FSI calculation method instead of hydrodynamic calculation can make the propeller performance calculation more accurate. Sobol algorithm is used for DoE, the correlation between propeller parameters and the objective function is analyzed to obtain propeller sensitive parameters. The sensitive parameters are optimized by NSGA-II to obtain the best design scheme. Under the requirements of ensuring the thrust coefficient and structural strength of the propeller, the radial distribution of the skew, chord length, pitch, and camber is optimized, and finally, a design scheme with higher efficiency, larger thrust, and safer structure is obtained. Take the KP505 propeller as an example. The results show that the design method has higher efficiency and a wider solution set range, which is more suitable for practical engineering applications.

Experimental and Numerical Study on Ice Blockage Performance of Propeller in Cavitation Flow

Cavitation greatly affects the ice blockage performance of propellers in polar areas, while the combined effect of cavitation and ice blockage on propellers has rarely been considered. In this work, the propeller model test in the cavitation tunnel and the viscous flow CFD numerical simulation based on RANS were conducted. In the cavitation tunnel test, the ice blockage model was simulated by a water-insoluble rectangular solid block, and the ice blockage was measured by the distance between the solid block and the propeller. The thrust and torque in tests and simulations were discussed under the uniform flow and ice blockage scenarios, as well as the variation of cavitation excitation force, pressure distribution of blades, cavitation characteristics and vortex intensity with advance coefficient when σn = 1.5, L/D = 0.15 in an ice blockage environment. The research shows that the numerical simulation results based on overlapping grids are in good agreement with the model test results, and the mean hydrodynamic errors are within 5%. In the uniform flow test, when the advance coefficient is small, the thrust and torque of the propeller will experience a sharp drop due to the influence of heavy cavitation. In the ice blockage test, the thrust and torque increase with the decrease of ice-propeller spacing, and the ice blockage becomes more serious as the cavitation grows. The propeller oscillates violently due to the cavitation excitation force, and the oscillation frequency increases with the increase of the advance coefficient. The cavitation is generated in the low-pressure area of the suction surface, and the cavitation shape captured in the present numerical simulation is consistent with the experimental phenomenon. Since the cavitation reduces the contact area between the water and the blade, the vortex strength will be reduced for the attachment of cavitation, and the vortex strength increases with the increase of the advance coefficient. This study will explore more hydrodynamic regularities with ice-class propellers in an ice blockage environment when cavitation occurrs, and provide technical support for the design of propellers of polar ships.

Cavitation erosion risk assessment on a full-scale steerable thruster

Propeller cavitation erosion prediction at an early design stage is becoming more and more important since it is one of the key constraints in the search for maximum propeller efficiency. Despite the experience from model tests, cavitation erosion research on actual ship scale is very limited. In this study, an attempt is made to assess the erosion risk on the blades of a full-scale steerable thruster of a tug boat. Pressure side cavitation was detected on board for three different propeller designs. For the first time, a cavitation erosion analysis is performed on ship-scale, using a rigorous potential energy approach, which accounts for the focusing of the potential energy at the collapse center during the cavity collapse. A full sensitivity study has been performed for the blade surface accumulated energy. The erosion model shows the erosion risk for different propeller designs applied on the vessel, and different operating conditions, by looking at the surface specific energy on the blade. The erosion analysis shows locations of high erosion risk that show a good resemblance with the actual damage locations on the real blades.

Метод пересчета результатов модельных испытаний гребного винта на натурные условия

Object and purpose of research. This paper discusses numerical method for simulation of propeller parameters in model and full-scale conditions. The purpose is to develop a similar methods for extrapolation of propeller model test data to the full-scale. Materials and methods. Propeller parameters are simulated as per the improved numerical method of E. Papmel. The flow around cylindrical section profiles of blades and hub is simulated as per the methods of boundary integral equations and integral calculation methods for the boundary layer with consideration of laminary-to-turbulent transition. Main results. Development of the method taking into account scale effect for propellers. The method has been applied to extrapolate model test data to the full scale. Conclusion. The method is of practical value for modern propeller design.

Aircraft Propeller Design through Constrained Aero-Structural Particle Swarm Optimization

An aero-structural algorithm to reduce the energy consumption of a propeller-driven aircraft is developed through a propeller design method coupled with a Particle Swarm Optimization (PSO). A wide range of propeller parameters is considered in the optimization, including the geometry of the airfoil at each propeller section. The propeller performance prediction tool employs a convergence improved Blade Element Momentum Theory fed by airfoil aerodynamic characteristics obtained from XFOIL and a validated OpenFOAM. A stall angle correction is estimated from experimental NACA 4-digits data and employed where convergence issues emerge. The aerodynamic data are corrected to account for compressibility, three-dimensional, viscous, and Reynolds number effects. The coefficients for the rotational corrections are proposed from experimental data fitting. A structural model based on Euler-Bernoulli beam theory is employed and validated against Finite Element Analysis, while the impact of centrifugal forces is discussed. A case of study is carried out where the chord and pitch distributions are compared to minimal losses distribution from vortex theory. Wind tunnel tests were performed with printed propellers to conclude the feasibility of the entire routine and the differences between XFOIL and CFD optimal propellers. Finally, the optimal CFD propeller is compared against a commercial propeller with the same diameter, pitch, and operational conditions, showing higher thrust and efficiency.

Modeling the Turbulence Spectrum Dissipation Range for Leading-Edge Noise Prediction

Noise pollution caused by inflow turbulence is a major problem in many applications, e.g., propellers and fans. The Amiet leading-edge noise prediction model is widely applied in the design of silent propellers and fans, strongly relying on the accuracy of the inflow turbulence spectrum. The von Kármán energy spectrum accurately models the energy-containing range and inertial subrange of the turbulence spectrum. However, this model does not incorporate the dissipation range of the turbulent energy and leads to incorrect far-field noise estimates in the high-frequency range. In this study, empirical formulations are presented for the dissipation frequency and the dissipation range based on experimental data. Two passive grids were used to generate nearly isotropic inflow turbulence, which was characterized by hot-wire anemometry. These results showed that the dissipation frequency depends on the intensity of the velocity fluctuations and on the freestream velocity. The expressions proposed to predict the dissipation frequency and the dissipation range had a fairly good agreement with the measured data in this research and with experimental data from the literature. The predicted leading-edge noise is significantly affected by the dissipation range, causing a decrease in level of up to 17 dB for the highest frequencies.

Effect of Groove Size on Aerodynamic Performance of a Low Reynolds Number UAV Propeller

Small-scale propellers typically have low aerodynamic efficiency. Improving the aerodynamic performance and efficiency of these propellers will enhance the endurance and operational range of UAVs. The desired requirement is a propeller design that can produce improved thrust and reduced torque. In order to fulfil such an objective, a novel technique known as the grooved design is studied on a small-scale propeller. Numerical investigations are performed on Applied Precision Composites 10×7 Slow Flyer propeller. Computational Fluid Dynamics is used to analyze this novel design. The grooved cross-sections considered have a rectangular geometry measuring 0.1×0.1mm and 0.1×0.2mm which are placed at 0.09c, 0.17c, 0.32c and 0.42c from the leading edge. The results of the study showed that the presence of grooves had modified the flow characteristics only to detrimentally impact the thrust performance. However, the grooves improved power performance due to torque reduction. The analysis of the KP results showed, in most models, the low torque relative to the baseline in the operational range of the low to medium advance ratio range. The improvement in torque, however, did not improve efficiency in all models.

Investigation into the Hydrodynamic Noise Characteristics of Electric Ducted Propeller

Ducted propeller is a kind of special propeller widely used in unmanned underwater vehicles, its flow characteristics and hydrodynamic noise are very important for marine environmental protection and equipment concealment. The hybrid techniques based on the acoustic analogy theory are adopted in the present study to calculate the unsteady flow field and sound field characteristics of a ducted propeller. The full scale flow filed and hydro-acoustic sources of the propulsion system are simulated by Detached-Eddy computational fluid dynamics (CFD) method. Hydrodynamic noise are calculated by FWH equation based on the CFD results. The frequency domain and directivity of sound pressure level at different sound field monitoring points are analyzed at four navigational speeds. The results show that the navigational speed that is in the inflow condition of the ducted propeller play important roles in the flow structure and underwater radiated noise. Under the fixed impeller rotational speed, the propulsion efficiency of ducted propeller increases first and then decreases with the raise of navigational speed. The maximum errors of thrust and power between simulation and experiment values are 0.5% and 0.1% respectively, which means that the adopted DES numerical simulation method has high credibility in calculating the acoustic source. At impeller rotational speed of 2000 r/min, the best state of flow field distribution is at the navigational speed of 1.54 m/s, which is corresponding to the highest propulsion efficiency condition. The propeller noise presents dipole characteristic in all working conditions, and at the obvious blade passing frequency, multiple characteristics are presented; most of the noise contribution is also concentrated below four times of the blade passing frequency. The total sound pressure level of the hydrodynamic noise is the smallest at the optimal efficiency condition (the navigational speed is 1.54 m/s). At high navigational speed, the low frequency characteristics below blade passing frequency increase and the amplitude becomes larger. This indicates that the component of turbulent noise becomes more important with the increase of navigational speed. The research focuses on analyzing the relationship between the energy loss of the ducted propeller wake field and the noise level, and it is found that the vortex at the tail makes a certain contribution to the noise. The research conclusions could provide some reference for the acoustic performance evaluation and noise reduction optimization of ducted propeller design as well as the improvement of UUV stealth performance.

A Propulsion System Design Methodology Based on Overall Efficiency Optimization for Electrically Powered Vessels

Boats are an important mean of transport, for passengers and cargo, mainly in countries with high water wealth. Nowadays, electrification of transport includes water alternatives, but the efficient use of energy is still a key issue. Energy consumption in electrically powered boats is highly influenced by several technical domains (e.g., hydrodynamics, battery, and propulsion). As literature reports advances in some of those domains, this article focuses on the “propulsion system (PS)” (motor–transmission–propeller) design and optimization. When implementing an electric motor, the interaction of mechanical components may be analyzed to find the optimal variables that will define the boat performance and the optimal motor–transmission–propeller combination. This article presents a methodology for multivariable optimization to maximize the overall efficiency of the PS, and therefore autonomy, in electric boats design. It proposes an approach from the physical variables that define the performance of the PS’s components, through an optimality problem formulation and an exhaustive search model that considers all possible values of the key design parameters. A case study is presented for an electrically powered riverboat, where the proposed methodology enabled an improvement between 4% and 5% in the overall efficiency of the PS. This allows better use of the limited available energy with a gain of 2.9 km (7%) in the most favorable case.