Stuttgart, Univ., Diss., 2005. / Print-Ausg. bei Jost-Jetter, Heimsheim erschienen.

This thesis deals with the design of electrical control for a constant speed propeller. The objective of this paper is to demonstrate the propeller governor design process on a case example of a DMP-3 propeller paired with a Rotax 912 ULS, using knowledge of flight mechanics, electrical engineering and automation. The scope of this thesis addresses the problems of propeller pitch control using an electrically driven linear actuator. In conclusion, this paper compares the benefits of the DMP-3 constant speed propeller, considering its use in existing airplanes within the UL-2 and CS-LSA category. Furthermore, it evaluates the capabilities of the proposed electronic governor, and outlines possibility of further development in this field.

Os papéis científicos estão cada vez mais eliminando as fronteiras entre ciência e negócios. A tríplice hélice (TH) é reconhecida como uma abordagem que propõe um modelo de sistema de inovação para o desenvolvimento regional, que incentiva a criação de spin-offs através de ambientes de inovação constituídos por atores locais (academia, indústria e governo), incentivando transição para uma sociedade baseada no conhecimento. O objetivo do estudo é medir o quanto a Universidade de Caxias do Sul pode ser considerada empreendedora na percepção dos seus stakeholders. O objeto de pesquisa é a Universidade de Caxias do Sul (UCS) que desenvolve, entre suas atividades, programas específicos para o empreendedorismo como o Startucs, a Incubadora Tecnológica (ITEC), escritório de transferência de tecnologia (ETT-UCS) e o Parque de Ciência, Tecnologia e Inovação (TecnoUcs). Este estudo se caracteriza de natureza quantitativa, com finalidade exploratória e descritiva. Referente aos procedimentos de análise, optou-se por realizar análise descritiva e análise multivariada (análise fatorial confirmatória, regressão linear e anova post-hoc). Os principais resultados encontrados apontam convergência na percepção em todos os perfis de stakeholders onde a média geral do estudo apontou que a UCS tem média de μ4,53 em uma escala de 1 a 7. Notou-se que os stakeholders que se utilizam das atividades filantrópicas da instituição tendem a atribuir médias maiores, enquanto empresários e professores são mais criteriosos em suas avaliações. / The scientific papers are increasingly eliminating the boundaries between science and business. The triple helix (TH) is recognized as an approach that proposes a model of innovation system for regional development, which encourages the creation of spin-offs through innovation environments made up of local actors (academia, industry and government), encouraging transition to a knowledge-based society. The main objective of the study is to measure how much the University of Caxias do Sul can be considered entrepreneurial in the perception of its stakeholders. The research object of this study is the University of Caxias do Sul (UCS), which develops, among its activities, specific programs for entrepreneurship such as Startucs, Technological Incubator (ITEC), technology transfer office (ETT-UCS) and the Science, Technology and Innovation Park (TecnoUcs). This study is characterized by a quantitative nature, with an exploratory and descriptive purpose. Regarding the analysis procedures, it was chosen to perform descriptive analysis and multivariate analysis (confirmatory factor analysis, linear regression and post-hoc anova). The main results show a convergence in perception in all the profiles of stakeholders where the general mean of the study indicated that the UCS has a mean of μ4,53 on a scale of 1 to 7. It was noted that the stakeholders who use the philanthropic activities of the institution tend to attribute higher averages, while entrepreneurs and teachers are more judicious in their evaluations.

This diploma thesis deals with optimization of propellers with the aim to reduce their noise level. Based on the measurement of noise level of serial propellers, major propeller noise sources were evaluated. Subsequent 2D simulations of the flow on the individual profiles along the propeller span revealed the locations of separation bubbles, which were identified as a potential source of the noise. Based on these findings, propellers were equipped with turbulator trips of various dimensions and their effect on the noise level and efficiency of the propellers was experimentally verified. The results did not show contribution of turbulator trips to noise reduction or efficiency.

The doctoral thesis deals with fatigue life evaluation of composites structures. The thesis pro-vides complex review of problematic and it is based on recent situation assessment. The main ob-jective of the thesis is to design the methodology of fatigue life evaluation of composites struc-tures. The designed methodology is applied to fatigue life evaluation of sailplane wing and propel-ler blades. One part of the thesis deals with laboratory fatigue tests of composite specimens which are intended for comparison of the effect of manufacturing technology and environment condition.

Many Small Unmanned Aerial Vehicles (SUAV) are driven by small scale, fixed blade propellers. The flow produced by the propeller, known as the propeller slipstream, can have significant impact on SUAV aerodynamics. In the design and analysis process for SUAVs, numerous Computational Fluid Dynamic (CFD) simulations of the coupled aircraft and propeller are often conducted which require a time-averaged, steady-state approximation of the propeller for computational efficiency. Most steady-state propeller models apply an actuator disk of momentum sources to model the thrust and swirl imparted to the flow field by a propeller. These momentum source models are based on simplified theories which lack accuracy. Currently, the most common momentum source models are based on blade element theory. Blade element theory discretizes the propeller blade into airfoil sections and assumes them to behave as two-dimensional (2D) airfoils. Blade element theory neglects many 3D flow effects that can greatly affect propeller performance limiting its accuracy and range of application. The research work in this dissertation uses a surrogate modeling method to develop a more accurate momentum source propeller model. Surrogate models for the time averaged thrust and swirl produced by each blade element are trained from a database of timeurate, highidelity 3D CFD propeller simulations. Since the surrogate models are trained from these highidelity CFD simulations, various 3D effects on propellers are inherently accounted for such as tip loss, hub loss, post stall effect, and element interaction. These efficient polynomial response surface surrogate models are functions of local flow properties at the blade elements and are embedded into 3D CFD simulations as locally adaptive momentum source terms. Results of the radial distribution of thrust and swirl for the steady-state surrogate propeller model are compared to that of time-dependent, highidelity 3D CFD propeller simulations for various aircraft-propeller coupled situations. This surrogate propeller model which is dependent on local flow field properties simulates the time-averaged flow field produced by the propeller at a momentum source term level of detail. Due to the nature of the training cases, it also captures the accuracy of time-dependent 3D CFD propeller simulations but at a much lower cost.

The Cassini spacecraft orbited Saturn for over 13 years and collected stellar occultations using an Ultraviolet Imaging Spectrograph (UVIS). Chord occultations were analyzed using autocorrelations at minimum ring plane radius to visualize the structure and correlation in the azimuthal direction. These particle tracking occultations cut a chord across the rings in the path of the star. By taking the autocorrelation of these chord occultations, 8 out of the 66 showed clumping within the first 3.0 km in azimuth, representing signs of a structure. Six of those occultations could be moonlets or propellers as their minimum ring plane radii are in the Propeller Belt region. The Fast Fourier Transform Power Spectrum of the autocorrelation was also taken, and 6 of the 8 had high peak power outputs at certain wavelengths. It is also observed that five of the occultations may contain self-gravity wakes.

Analysis of the aerodynamic effects of a propeller flowfield on bodies downstream of the propeller is a complex task. These interaction effects can have serious repercussions for many aspects of the vehicle, including drag changes resulting in larger power requirements, stability changes resulting in adjustments to stabilizer sizing, and lift changes requiring wing planform adjustments. Historically it has been difficult to accurately account for these effects at any stage during the design process. More recently methods using Euler solvers have been developed that capture interference effects well, although they don't provide an ideal tool for early stages of aircraft design, due to computational cost and the time and expense of setting up complex volume grids. This research proposes a method to fill the void of an interference model useful to the aircraft conceptual and preliminary designer. The proposed method combines a flexible and adaptable tool already familiar to the conceptual designer in the aerodynamic panel code, with a pseudo-steady slipstream model wherein rotational effects are discretized onto vortex particle point elements. The method maintains a freedom from volume grids that are so often necessary in the existing interference models. In addition to the lack of a volume grid, the relative computational simplicity allows the aircraft designer the freedom to rapidly test radically different configurations, including more unconventional designs like the channel wing, thereby providing a much broader design space than otherwise possible. Throughout the course of the research, verification and validation studies were conducted to ensure the most accurate model possible was being applied. Once the vortex particle scheme had been verified, and the ability to model an actuator disk with vortex particles had been validated, the overall product was compared against propeller-wing wind tunnel results conducted specifically as benchmarks for numerical methods. The method discussed in this work provides a glimpse into the possibility of pseudo-steady interference modeling using vortex particles. A great groundwork has been laid that already provides reasonable results, and many areas of interest have been discovered where future work could improve the method further. The current state of the method is demonstrated through simulations of several configurations including a wing and nacelle and a channel wing.

The inboard-winglet concept was examined for its flow characteristics by testing for pressure coefficients over the wing and winglet surface in the Virginia Tech Stability Wind Tunnel over a range of freestream velocity and angle of attack. The results were analytically applied to calculate aircraft performance of a roadable aircraft, Pegasus II, which used the inboard-winglet concept in its design. The results proved that this concept has the potential to increase a wing lift coefficient at the right combination of thrust setting and freestream velocity better than a conventional wing-propeller arrangement. The lift coefficient inside the winglet channel was approximated as 2D in behavior. It is also shown that the winglets produce thrust at a positive-lift wing configuration. In the Pegasus II, the vertical stabilizers act like inboard winglets and produce a thrust component from its resultant force, giving 5.2% improvement in its effective aspect ratio and resulting in an induced-drag decrease. With an application of the new wing concept, the Pegasus II performance is comparable to other general aviation aircraft. / Master of Science

This master’s thesis is aimed to examine the possible range increase of a ballistically fying body equipped with a propeller working at transonic velocities. To determine whetherthe propeller will provide an improvement in range, results from simulations are compared to corresponding cases of similar bodies fying without a propeller. Different airfoil geometries were examined using the computer software Fluent. Thereafter, a geometry was created from scratch based on wing and propeller theory and was simulated on using the computer software ICFD++ which, may be used for computational fuid dynamics. According to the simulations the increase in range was shown to be 3-4% further for the specifc projectile chosen for this work. For the furthest fying cases the initial velocity of the body was higher than what the propeller had been optimized for, and regions of supersonic velocities developed on the geometry. This did however not impose any substantial impediments according to the simulations, although a field test would likely have displayed stalling and following, a worsening of performance. / Detta examensarbete syftar att undersöka räckviddspåverkan på en annars ballistiskt flygande kropp vars bakparti försatts med en propeller färdandes i transsoniska hastigheter. För att bedöma huruvida detta kan vara till nytta, ställs resultatet från simuleringar med propeller upp mot resultatet för motsvarande fall utan propeller. En geometri har skapats med grund i ving-och propellerteori och därefter har simuleringar utförts i mjukvaran ICFD++, som används till beräkningar av strömningsmekanik. Avseende räckviddspåverkan visade simulationerna på en ökning av räckvidden på drygt 3-4% längre avstånd för den specifka projektil som hade valts att simulera på. För de längre fallen gällde dock en högre utskjutningshastighet än vad propellern var väl anpassad för och områden av överljudshastigheter utvecklades på geometrin. Detta visade ingen betydlig påverkan i simulationerna men verkliga tester hade sannolikt visat på överstegring och med det en försämrad prestanda.