Determination of Fatigue Life of Surface Propeller by Using Finite Element Analysis

Propeller design aims at achieving high propulsive efficiency at low levels of vibration and noise, usually with minimum cavitations. Achieving this aim is difficult with conventional propellers, as ships have become larger and faster propeller diameters have remained limited by draught and other factors. Surface piercing propeller offers an attractive alternative to high-speed crafts, which operate under limited draught. The performance of the vehicle depends upon the efficiency of the propeller. The geometric shape and its surface finish will decide the efficiency of the propeller. The material used is carbon UD and aluminum. The present project basically deals with the modeling, Analysis of the propeller using composite material of a marine vehicle having low draft. A propeller is complex 3D model geometry. CATIA modeling software is used for generating the blade model and tool path on the computer. Sectional data, pitch angle of the propeller are the inputs for the development of propeller model. Finite element analysis was carried out using ABAQUS. The propeller model developed in CATIA is converted in to IGES file and then imported to HYPERMESH for developing fine mesh of the model. As a part of the analysis static structural testing was conducted by varying material properties in pre-processing stage. Further fatigue analysis was performed to analyze the factor of safety. Based on the results obtained from both static analysis and dynamic analysis a better performing material is identified for the development of a propeller. The post processed results obtained from both analysis methods recommends carbon UD/ Epoxy for the fabrication of propeller

Pitch Control of Horizontal Axis Wind Turbine

Wind energy is fast becoming the most preferable alternative to conventional sources of electric power. Owing to the perennial availability of wind and the considerable range of power control, wind turbines are now coming up in almost all parts of the world. In the early days of development, wind turbines were designed to rotate at constant speed through pitch control or stall control. The modern wind turbines implement pitch control in order to tap maximum energy at wind speeds lower than rated wind speed. In this project, three different models of pitch actuator system have been studied and a discrete time adaptive PID model has been proposed where the gains of the PID controller are modified based on the time response parameters of the previous time cycle. It is expected to offer better control over a wide range of wind speeds. Keywords: Pitch control, renewable energy, adaptive PID Control, Wind Energy Conversion System

Desenvolvimento de uma ferramenta computacional de código aberto para projecto de hélices no âmbito do projecto MAAT

This thesis presents the development of a new propeller design and analysis software capable of adequately predicting the low Reynolds number performance. JBLADE software was developed from QBLADE and XFLR5 and it uses an improved version of Blade Element Momentum (BEM) theory that embeds a new model for the three-dimensional flow equilibrium. The software allows the introduction of the blade geometry as an arbitrary number of sections characterized by their radial position, chord, twist, length, airfoil and associated complete 360º angle of attack range airfoil polar. The code provides a 3D graphical view of the blade, helping the user to detect inconsistencies. JBLADE also allows a direct visualization of simulation results through a graphical user interface making the software accessible and easy to understand. In addition, the coupling between different JBLADE modules avoids time consuming operations of importing/exporting data, decreasing possible mistakes created by the user. The software is developed as an open-source tool for the simulation of propellers and it has the capability of estimating the performance of a given propeller geometry in design and off-design operating conditions. The current development work was focused in the design of airship propellers. The software was validated against different propeller types proving that it can be used to design and optimize propellers for distinct applications. The derivation and validation of the new 3D flow equilibrium formulation are presented. This 3D flow equilibrium model accounts for the possible radial movement of the flow across the propeller disk, improving the performance prediction of the software. The development of a new method for the prediction of the airfoil drag coefficient at a 90 degrees angle of attack for a better post-stall modelling is also presented. Different post-stall methods available in the literature, originally developed for wind turbine industry, were extended for propeller analysis and implemented in JBLADE. The preliminary analysis of the results shows that the propeller performance prediction can be improved using these implemented post-stall methods. An inverse design methodology, based on minimum induced losses was implemented in JBLADE software in order to obtain optimized geometries for a given operating point. In addition a structural sub-module was also integrated in the software allowing the estimation of blade weight as well as tip displacement and twist angle changes due to the thrust generation and airfoil pitching moments. To validate the performance estimation of JBLADE software, the propellers from NACA Technical Report 530 and NACA Technical Report 594 were simulated and the results were checked against the experimental data and against those of other available codes. The inverse design and structural sub-module were also validated against other numerical results. To verify the reliability of XFOIL, the XFOIL Code, the Shear Stress Transport k-ω turbulence model and a refurbished version of k-kl-ω transition model were used to estimate the airfoil aerodynamic performance. It has been shown that the XFOIL code gives the closest prediction when compared with experimental data, providing that it is suitable to be used in JBLADE Software as airfoil’s performance estimation tool. Two different propellers to use on the MAAT high altitude cruiser airship were designed and analysed. In addition, the design procedure and the optimization steps of the new propellers to use at such high altitudes are also presented. The propellers designed with JBLADE are then analysed and the results are compared with conventional CFD results since there is no experimental data for these particular geometries. Two different approaches were used to obtain the final geometries of the propellers, since, instead of using the traditional lift coefficient prescription along the blade, the airfoil’s best L3/2/D and best L/D were used to produce different geometries. It was shown that this new first design approach allows the minimization of the chord along the blade, while the thrust and propulsive efficiency are maximized. A new test rig was developed and used to adequately develop and validate numerical design tools for the low Reynolds numbers propellers. The development of an experimental setup for wind tunnel propeller testing is described and the measurements with the new test rig were validated against reference data. Additionally, performance data for propellers that are not characterized in the existing literature were obtained. An APC 10”x7” SF replica propeller was built and tested, providing complementary data for JBLADE validation. The CAD design process as well as moulds and propeller manufacture are also described. The results show good agreement between JBLADE and experimental performance measurements. Thus it was concluded that JBLADE can be used to design and calculate the performance of the MAAT project high altitude cruiser airship propellers.Nesta tese é apresentado o desenvolvimento de um novo código para projeto e análise de hélices, capaz de prever adequadamente o desempenho a baixos números de Reynolds. O JBLADE foi desenvolvido partindo dos códigos QBLADE e XFLR5 e utiliza uma versão aperfeiçoada da teria do elemento da pá que contém um novo modelo que considera o equilíbrio tridimensional do escoamento. O código permite que a pá seja introduza como um número arbitrário de secções, caracterizadas pela sua posição radial, corda, ângulo de incidência, comprimento, perfil e ainda pela polar 360º associada ao perfil. O código permite uma visualização gráfica em 3D da pá, ajudando o utilizador a detetar possíveis inconsistências. O JBLADE também permite uma visualização direta dos resultados das simulações através de um interface gráfico, tornado o código acessível e de fácil compreensão. Além disso, a interligação entre os diferentes módulos do JBLADE evita operações demoradas de importação e exportação de dados, diminuindo assim possíveis erros criados pelo utilizador. O código foi desenvolvido como um código aberto, para a simulação de hélices, e que tem a capacidade de estimar o desempenho de uma determinada geometria de hélice nas condições de operação do seu ponto de projeto e fora do seu ponto de projeto. O trabalho de desenvolvimento aqui apresentado foi focado no projeto de hélices para dirigíveis de grande altitude no âmbito do projeto MAAT (Multibody Advanced Airship for Transportation). O software foi validado para diferentes tipos de hélice, provando que pode ser utilizado para projetar e otimizar hélices para diferentes finalidades. São apresentadas a derivação e validação do novo modelo de equilíbrio tridimensional do escoamento. Este modelo de equilíbrio 3D tem em conta o possível movimento radial do escoamento ao longo do disco da hélice, melhorando as estimativas de desempenho do software. O desenvolvimento de um novo método para a estimativa do coeficiente de arrasto dos perfis a 90º, permitindo uma melhor modelação do desempenho pós-perda é também apresentado. Diferentes modelos de pós perda presentes na literatura e originalmente desenvolvidos para a indústria das turbinas eólicas foram implementados no JBLADE e a sua aplicação a hélices para melhorar a estimativa do desempenho foi analisada. Os resultados preliminares mostraram que a estimativa de desempenho das hélices pode ser melhorada, utilizando estes modelos de pós-perda. Uma metodologia de projeto inverso, baseada no mínimo das perdas induzidas foi implementado no JBLADE, de modo a ser possível obter hélices com geometrias otimizadas para um dado ponto de projeto. Além disto, um módulo de cálculo estrutural foi também implementado, permitindo estimar o peso das pás, a deformação das mesmas, quer em termos de flexão, quer em termos de torção, devido à tração gerada pela própria hélice e aos momentos do perfil. Para validar as estimativas de desempenho do JBLADE foram utilizadas hélices originalmente apresentadas nos relatórios técnicos NACA, nomeadamente no relatório técnico 594 e 530. Estas hélices foram simuladas no JBLADE e os resultados foram comparados com os dados experimentais e com as estimativas de desempenho obtidas através de outros códigos numéricos. O módulo de projeto inverso e o módulo estrutural foram também validados, através da comparação com outros resultados numéricos. De modo a verificar a fiabilidade do código XFOIL usado no JBLADE para previsão das características dos perfis das pás, o modelo de turbulência k-ω Shear Stress Transport e uma versão reformulada do modelo de transição k-kl-ω foram utilizados em simulações RANS para comparação dos resultados do desempenho aerodinâmico de perfis. Os resultados mostraram que o código XFOIL dá uma estimativa de desempenho mais próxima dos dados obtidos experimentalmente do que os modelos RANS CFD, provando que pode ser utilizado no JBLADE como ferramenta de estimava de desempenho aerodinâmico dos perfis. Em vez da tradicional prescrição do coeficiente de sustentação ao longo da pá para melhor L/D, foi utilizado os pontos de melhor L3/2/D para o projeto de uma hélice para o dirigível cruzador do projeto MAAT. Os procedimentos de otimização empregados ao longo do processo de projeto destas hélices para utilização em grandes altitudes são também descritos. As hélices projetadas com o JBLADE foram analisadas e os resultados obtidos foram comparados com simulações convencionais de dinâmica de fluidos computacional, uma vez que não existem dados experimentais para estas geometrias em particular. Foram utilizadas duas aproximações diferentes de modo a obter duas geometrias finais. Foi mostrado que esta nova abordagem de projeto de hélices leva à minimização da corda necessária ao longo da pá, enquanto a tração e a eficiência da hélice são maximizadas. Foi desenvolvida uma nova instalação experimental para ensaio e caracterização de hélices de baixo número de Reynolds no âmbito do projeto MAAT, que foi posteriormente utilizada para desenvolver e validar ferramentas numéricas para projeto destas hélices. Além da descrição do desenvolvimento da instalação experimental, é também apresentada a validação da mesma, através da comparação das medições de diferentes hélices com dados experimentais presentes na literatura, obtidos em diferentes instalações de referência. Foi construída e testada uma réplica da hélice APC 10”x7” SF, fornecendo dados adicionais para a validação do JBLADE. É ainda apresentado o processo de desenho da réplica no software CAD e de construção dos moldes e do protótipo da hélice. Os resultados mostraram uma boa concordância entre as estimativas do JBLADE e as medições experimentais. Assim, conclui-se que o JBLADE pode ser utilizado para projetar e estimar o desempenho das hélices que poderão ser utilizadas pelo dirigível cruzador do MAAT bem como em outras aplicações

Aeronautical Engineering: A special bibliography with indexes, supplement 55

This bibliography lists 260 reports, articles, and other documents introduced into the NASA scientific and technical information system in February 1975

Design And Analysis Of Cold Forged AUV Propeller

Most of power of an Autonomous Underwater Vehicle (AUV) is utilized by its propulsion system. Since AUV power only depends on onboard battery, the power consumption becomes crucial issue in optimizing the AUV performance. In this research a propeller need to be fabricated for AUV that will be developed by Underwater Robotic Research Group (URRG). The specific propeller design must be discovered in order to optimize the AUV power consumption. PVL code that has been developed by Kerwin (2001) was used as a tool to design the specific propeller

Manufacturing, Analysis, and Experimental Testing of Multi-bladed Propellers for SUAS

The emergence of small UAS with infinite applications has increased the demand for improved small aircraft components. For custom built UAS, optimized propellers are rarely available off the shelf. This paper presents a unique method for creating multi-bladed composite propellers that are optimized to a specific vehicle's thrust and noise requirements. The composite propellers are experimental tested to verify their performance parameters. This method produces high quality propellers that are comparable to commercially available ones with the advantage of better vehicle performance.Mechanical & Aerospace Engineerin

Analysis of a small-scale horizontal axis wind turbine blade using FEA approach

Abstract: Increasing cost of energy, and environmental concerns are currently forcing many nations around the world to develop diverse sources of clean, renewable energy as alternative to none-renewable fossil fuel driven energy systems. One of the clean energy alternatives that is widely explored due to high reliability is wind turbine energy systems. For optimized design in these systems, stress analysis and deformation of turbine blades are highly essential components that must be considered in the design phase due to significant influence on reliability, performance and longevity of the system. The study focused on the design of a turbine blade to improve on existing turbine blade by performance analysis using Inventor professional software for the Finite Element Analysis (FEA). The design, and performance analysis was based on a 1kva small-scale horizontal axis wind turbine blade prototype which can be scaled up based on the design specification and material performance criteria...M.Tech. (Mechanical Engineering

Large scale prop-fan structural design study. Volume 1: Initial concepts

In recent years, considerable attention has been directed toward improving aircraft fuel consumption. Studies have shown that the inherent efficiency advantage that turboprop propulsion systems have demonstrated at lower cruise speeds may now be extended to the higher speeds of today's turbofan and turbojet-powered aircraft. To achieve this goal, new propeller designs will require features such as thin, high speed airfoils and aerodynamic sweep, features currently found only in wing designs for high speed aircraft. This is Volume 1 of a 2 volume study to establish structural concepts for such advanced propeller blades, to define their structural properties, to identify any new design, analysis, or fabrication techniques which were required, and to determine the structural tradeoffs involved with several blade shapes selected primarily on the basis of aero/acoustic design considerations. The feasibility of fabricating and testing dynamically scaled models of these blades for aeroelastic testing was also established. The preliminary design of a blade suitable for flight use in a testbed advanced turboprop was conducted and is described in Volume 2

Augmented Propeller Design with the use of a Passive Circulation Control Pressurization System

Circulation control is a high-lift device used on the main wing of an aircraft. This technology has been in the research and development phase for over sixty years primarily for fixed-wing aircraft when the early models were referred to as blown flaps. Circulation control works by increasing the near surface velocity of the airflow over the leading edge and/or trailing edge of a specially designed aircraft wing using a series of blowing slots that eject high velocity jets of air. The wing has a rounded trailing edge, and ejects the air tangentially, through these slots inducing the Coanda Effect. This phenomenon keeps the boundary layer jet attached to the wing surface longer than a conventional wing and thus increases the lift generated on the wing surface due to the relaxation of the Kutta Condition for the rounded trailing edge. The circulation control airflow adds to the lift force through conventional airfoil lift production, by altering the circulation of stream lines around the airfoil.;The main purpose of the circulation control for fixed wing aircraft is to increase the lifting force when large lifting forces and/or slow speeds are required, such as at take-off and landing. Wing flaps and slats are currently used during landing on almost all fixed wing aircraft and on take-off by larger jets. While flaps and slats are effective in increasing lift, they do so with a penalty of increased drag. The benefit of the circulation control wing is that no extra drag is created from the movement of surfaces into the airflow around the wing and the lift coefficient is greatly increased.;Taking advantage of circulation control generally includes the addition of extra weight to an aircraft or siphoning some of the power off the engine to run the circulation control hardware. It was the goal of this research to find an alternative way of pumping circulation control pressurization air to the trailing edge slot located on an unmanned aerial vehicle propeller. The design called for the rerouting of stagnation pressure on the frontal propeller area, through the inside of the propeller blades, to an ejection slot on the training edge of the propeller blade. This allowed for the forward velocity of the aircraft to drive the pressurization of the circulation control plenum passively, or without additional hardware.;For this study, a Clark-Y airfoil section propeller with an overall diameter of 24 inches was designed and tested in both a West Virginia University wind tunnel and the vertical wind tunnel at Wright-Patterson Air Force Base as well as computationally through the use of Fluent software and Blade Element Analysis methods. The comparison of both the augmented propeller and the unaugmented (baseline) propeller showed a 5.74 percent increase in efficiency by using the circulation control augmentation. This increase in efficiency is shown to act over the entire range of flight envelopes of the aircraft. It is shown to be particularly beneficial at advance ratios above 0.30, normal operating conditions of propeller driven UAV\u27s