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The work presented in this thesis was undertaken as part of the three-year ‘Jigless Aerospace Manufacture’ (JAM) project which was set-up to investigate and address the significant scientific, technological and economic issues to enable a new design, manufacture and assembly philosophy based on minimising product specific jigs, fixtures and tooling. The main goal of the JAM project at Cranfield was the development of appropriate jigless methods and principles, and the subsequent redesign of the JAM project demonstrator structure – a section of the Airbus A320 aircraft Fixed Leading Edge – to fully investigate and realise the capabilities of jigless methodologies and principles. The particular focus of research activity described in this thesis was the development of a methodology to design for jigless assembly and a process of selecting assembly features to enable jigless assembly. A review of the literature has shown that no methodologies exist to specifically design for jigless assembly; however, previous relevant research has been built upon and extended with the incorporation of novel tools and techniques. To facilitate the assembly feature selection process for jigless assembly, an Assembly Feature Library was created that broadened and expanded the conventional definition and use of assembly features. The developed methodology, assembly feature selection process and Feature Library have been applied and validated on the JAM project demonstrator structure to serve as a Case Study for the tools and techniques developed by the research. Additionally, a Costing Analysis was carried out which suggests that the use of the tools and techniques to enable jigless assembly could have a large and considerable impact on both the Non-Recurring and Recurring costs associated with the design, manufacture and assembly of aircraft.

Det finns kunskapsluckor att fylla när det gäller mikroplaster från vindkraftsblad. Denna studie bidrar med ökad kunskap om mikroplaster från erosionsskador på vindkraftsblad. Metoden som använts består av datainsamling från bladreparationer och manuell granskning av bladskador via plattformen IRIS från Clobotics. Resultatet visar att vindparken Mörtjärnberget (MTB) eroderar i snitt cirka fem gram mikroplaster per turbin per år eller cirka 1,8 kilo för hela parken per år och totalt cirka 14 kilo sedan etableringen. Skadeläget för Mörttjärnberget visar på att det finns erosionsskador på alla turbiner. Kemikalierna som sprids och påverkar miljön finns i coatingen (topplacken) det handlar om methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate och bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate. Dessa kemikalier är väldigt skadliga för vattenlevande organismer med långvarig effekt. Totalt har parken på MTB släppt ut 4,56 kilogram coating som innehåller de miljöfarliga ämnena. En slutsats från denna rapport är att utsläppen av mikroplaster från Mörtjärnberget i form av erosionsskador är lägre än vad flera tillverkare och vinkraftsägare uppger. En annan slutsats är att om mikroplaster släpps ut vid reparationen av erosionsskador i form av slipdamm så kan dammet spridas i den lokala miljön. Den högsta koncentrationen vid markytan beräknas vara efter 300 meter respektive 500 meter i vindens riktning med en vindhastighet på en meter per sekund beroende på atmosfärisk stabilitet. Mikroplasterna från reparation av erosionsskador kan hamna i avrinningsområden med en ekologisk status som kan försämras av mikroplaster. / There are knowledge gaps to be filled regarding microplastics from windturbine blades, this study contributes with increased knowledge about microplastics from erosion damage. The method used consists of data collection from blade repairs and manual review of blade damage via the IRIS platform from Clobotics. The results show that the Mörtjärnberget wind farm erodes an average of about five grams of microplastics per turbine per year or about 1.8 kilograms for the entire park per year and a total of about 14 kilograms since it was built. The damage situation for Mörttjärnberget shows that erosion damage is present on all turbines and all turbines have at least one more serious erosion damage that reach the layer filler. The chemicals that spread and affect the environment are found in the coating (topcoat), it is about methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate and bis (1,2,2,6,6-pentamethyl-4- piperidyl) sebacate. These chemicals are very harmful to aquatic organisms with long-term effects. In total, the park at MTB has released 4.56 kilograms of coating that contains environmentally hazardous substances. One conclusion from this report is that the emissions of microplastics from the Mörtjärnberget in the form of erosion damage are lower than what several manufacturers and what is said in the media. Another conclusion is that if microplastics are released during the repair of erosion damage in the form of grinding dust, the dust can be spread in the local environment. The highest concentration at the ground surface should be after 300 meters and 500 meters respectively in the direction of the wind with a wind speed of one meter per second depending on atmospheric stability. The microplastics from the repair of erosion damage can end up in watersheds with an ecological status that canbe degraded by microplastics. / <p>2023-11-03</p>

This dissertation presents measurements of the far-field noise associated with the interaction of grid-generated turbulence with a series of airfoils of various chord lengths, thicknesses, and camber. The radiated noise was measured for a number of angles of attack for each airfoil to determine the effects of angle of attack on the leading edge noise. Measurements are compared with numerous theories to determine the mechanism driving the production of leading edge noise. Calculations were also made using a boundary element method to determine the effects of airfoil shape on the unsteady loading spectrum on the different airfoils to attempt to explain the far-field noise. Measurements of the unsteady surface pressure on a single airfoil were made for a number of angles of attack to determine the effects of wind tunnel interference corrections on the unsteady surface pressure. These measurements were compared with those of Mish (2003) to determine the effects of the interference correction. An attempt was also made to correlate the unsteady loading on the airfoil with the far-field noise. The airfoils studied were a 0.203-m chord NACA 0012, a 0.61-m chord NACA 0015, a 0.914-m chord NACA 0012, a 0.914-m chord DU96, and a 0.914-m chord S831. All airfoils spanned the entire 1.83-m height of the test section. Measurements were made using the Virginia Tech Stability Wind Tunnel in its acoustic configuration with an anechoic test section with side walls made of stretched Kevlar fabric to reduce aerodynamic interference. Measurements were made in grid-generated turbulence with an integral length scale of 8.2-cm and a turbulence intensity of 3.9%. Far-field noise measurements were made at Mach numbers of 0.087 and 0.117 with various configurations of up to 4 Bruel and Kjaer microphones mounted at an observer angle of 90° measured from the wind tunnel axis. Unsteady surface pressure measurements were made on the NACA 0015 airfoil immersed in the same grid generated turbulence used in the far-field noise study. An array of microphones mounted subsurface along the airfoil chord and a spanwise row was used to measure the unsteady surface pressure. These measurements were made at angles of attack from 0 through 16° in 2° increments. Far-field noise measurements of the leading edge noise show a consistent angle of attack effect. The radiated noise increases as the angle of attack is increased over the frequency range. These effects are small for large integral scale to airfoil chord ratios. The larger airfoils have been shown to generate significantly less leading edge noise at high frequencies, but this effect does not appear to be solely dependent upon the leading edge radius. The leading edge noise can be predicted with accuracy using the method of Glegg et al. (2008). Unsteady surface pressure measurements have been shown to be largely independent of the wind tunnel interference correction as shown by comparison with Mish (2008). The same low frequency reduction described by Mish was seen for an interference correction that was nearly 30% larger. The unsteady sectional lift spectra have been shown to be related to the far-field noise spectra by a factor close to the dipole efficiency factor; however, no correlation could be found between the instantaneous unsteady surface pressure and the radiated noise. The spanwise averaged unsteady pressure difference spectra have been shown to be related to the far-field noise spectra by the dipole efficiency factor. / Ph. D.

The interaction of an unsteady wake with a solid body can induce sizable loading of the structure, which has many detrimental side effects in both the structural and acoustic senses. These interactions are ubiquitous in nature and engineering. A flow control technique is sought to mitigate this interaction, thereby decreasing the level of structural vibration. This thesis investigates the effectiveness of steady leading-edge blowing (LEB) flow control for modifying the vortex induced vibrations on an airfoil in the wake of a circular cylinder. The airfoil was allowed to oscillate perpendicular to the fluid flow direction in response to the impinging Von-Karman vortex street. The flow field and airfoil vibrations were simultaneously captured using Digital Particle Image Velocimetry (DPIV) and accelerometer measurements in a time-resolved sense. The results indicate that LEB can significantly reduce the degree of unsteady loading due to the blade vortex interaction (BVI). In some cases, the LEB jet appears to break the coherency of a vortex incident on the airfoil, and in other cases the jet increase the mean stand-off distance of the vortex as it convects over the airfoil surface. It was also found that, for large circular cylinders, if the airfoil is within the mean closure point of the circular cylinder wake, the LEB can increase the level of BVI. The Proper Orthogonal Decomposition (POD) was also used to analyze the DPIV data. POD is mathematically superior for reducing a data rich field into fundamental modes; a suitable basis function for the reduction is chosen mathematically and it is not left to the researcher to pick the basis function. A comparison of the energy in these modes is useful in ascertaining the dynamics of the BVI. For one of the two cases examined with POD, it was found for no LEB the fundamental (i.e. most energetic) mode is given by the vortex shedding of the circular cylinder upstream. The addition of LEB reduces the energy contained in this fundamental mode. Thus the LEB jet has the effect of reducing the flow field coherency; the structure of the large vortices is broken up into smaller vortices. For the other case, the LEB jet has the opposite effect: the jet has the ability to organize the circular cylinder wake into coherent structures. This acts to increase the coherency of the circular cylinder wake and increases the level of BVI. / Master of Science

In the military arena there is an increase in demand for Low Observable (LO) flight vehicles. This drive for low observability imposes limits on Leading Edge (LE) sweep angles and prohibits the use of a tailplane/fin resulting in unconventional configurations; a typical example of which are Unmanned Combat Aerial Vehicles (UCAVs). This class of aircraft poses stability and control problems due to the early onset of flow separation. The focus of this project is on the on the use of Tangential Leading Edge Blowing (TLEB) as a means of separation suppression on such vehicles. This project is unique in that the TLEB slot is positioned on the wing lower surface facing the oncoming freestream. Also, the model in this project is representative of the outboard panel of a UCAV wing, a geometry on which TLEB has not been explored in the past. A swept wing model (LE sweep = 47 degrees, AR = 3) was designed. The model has a TLEB nozzle with a slot on the lower surface at approx. 1% yawed chord that spans 0.58 m (approx. 70% LE length). Baseline wing characteristics were obtained with the full slot exposed. The wing showed a variation in pitch between CL = 0 and 0.6 which from oil flow visualisation is believed to be due to laminar separation. At CL = 0.6 there is a positive pitch break which flow visualisation suggests is due to the occurrence of a LE vortex. Sensitivity studies for slot configuration, Re number and transition fixing were carried out. The blowing rates 0.0025, 0.005, 0.025, 0.05 were tested for two slot lengths; one full span (0.58 m) and another third span positioned at the midpoint of the full slot. All blowing rates show some suppression of the LE vortex and therefore reduction in severity of the pitch break at CL = 0.6. High blowing rates produce a negative shift in CM, which CFD suggests is due to a large amount of suction produced on the lower wing surface adjacent to the slot exit. This means the available trim power is less than for the lower blowing rates. Wool tuft results for high blowing rates from the middle slot show an increase in streamwise flow at the TE suggesting TLEB is capable of improving the effectiveness of TE devices. The effectiveness of TLEB at low blowing rates has been shown to be high compared to that found in literature. A 1st order analysis of the impact of TLEB on a full scale system shows realistic options.

As the understanding of the workings of the biological world expands, biomimetic designs increasingly move into the focus of engineering research studies. For this thesis, two studiesinvolving leading edge vortex generation for lift production as observed in nature were explored intheir respective flow regimes. The first study focused on the steady state analysis of streamwise vortices generated byleading edge tubercles of an adult humpback whale flipper. A realistic scaled model of a humpbackflipper was fabricated based on the 3D reconstruction from a sequence of 18 images taken whilecircumscribing an excised flipper of a beached humpback whale. Two complementary modelswith smooth leading edges were transformed from this original digitized model and fabricatedfor testing to further understand the effect of the leading edge tubercles. Experimentally-obtainedforce and qualitative flow measurements were used to study the influence of the leading edgetubercles. The presence of leading edge tubercles are shown to decrease maximum lift coefficient(Cl ), but increase Cl production in the post-stall region. By evaluating a measure of hydrodynamicefficiency, humpback whale flipper geometry is shown to be more efficient in the pre-stall regionand less efficient in the post-stall region as compared to a comparable model with a smooth leadingedge. With respect to a humpback whale, if the decrease in efficiency during post-stall angles ofattack was only required during short periods of time (turning), then this decrease in efficiencymay not have a significant impact on the lift production and energy needs. For the pursuit ofbiomimetic designs, this decrease in efficiency could have potential significance and should beinvestigated further. Qualitative flow measurements further demonstrate that these force results aredue to a delay of separation resulting from the presence of tubercles.The second study investigated explored the effects of flapping frequency on the passive flowcontrol of a flapping wing with a sinusoidal leading edge profile. At a flapping frequency of f =0.05 Hz, an alternating streamwise vortical formation was observed for the sinusoidal leading edge,while a single pair of vortices were present for the straight leading edge. A sinusoidal leading edgecan be used to minimize spanwise flow by the generation of the observed alternating streamwisevortices. An increase in flapping frequency results in these streamwise vortices becoming stretchedin the path of the wing. The streamwise vortices are shown to minimize spanwise flow even afterbeing stretched. Once instabilities are formed at f ≥ 0:1 Hz due to velocity shearing generatedby the increase in cross-radial velocity, the alternating streamwise vortices begin to break downresulting in a increase of spanwise flow.

O presente trabalho tem por finalidade a obtenção de curvas que regem o comportamento estático da sustentação e arrasto de uma asa em função da variação de seu câmber através do uso do flape de bordo de ataque, com base em resultados experimentais obtidos em túnel de vento. O estudo inclui uma revisão sobre o uso de flapes de bordo de ataque e uma descrição dos ensaios em túnel de vento. O modelo tridimensional da asa utilizada para os experimentos contém um flape de bordo de ataque em metade de sua envergadura e foi construído segundo o perfil GA(W)-1. O experimento inclui a determinação da sustentação e do arrasto para cada valor do ângulo de ataque da asa e do ângulo do flape de bordo de ataque. O objetivo é obter uma correlação ótima entre estes dois ângulos de forma que, para cada ângulo de ataque da asa seja determinado um ângulo ótimo do flape de bordo de ataque que confira a máxima sustentação. / The present work has for purpose the attainment of curves that conduct the static behavior of the lift and drag of a wing in function of the variation of its camber through the use of the leading edge flap, on the basis of gotten experimental results obtained in the wind tunnel. The study includes a revision of the use of leading edge flaps and a description of the wind tunnel tests. The three-dimensional model of the wing used in the experiments contains a leading edge flap along half of the span and was constructed with a GA(W)-1 section profile. The experiment includes the determination of lift and drag for each value of angle of attack of the wing and each angle of the leading edge flap. The objective is to obtain a good correlation between the two angles in such a way that, for each angle of attack of the wing there is determined an excellent angle of the leading edge flap that confers principle lift.

O presente trabalho tem por finalidade a obtenção de curvas que regem o comportamento estático da sustentação e arrasto de uma asa em função da variação de seu câmber através do uso do flape de bordo de ataque, com base em resultados experimentais obtidos em túnel de vento. O estudo inclui uma revisão sobre o uso de flapes de bordo de ataque e uma descrição dos ensaios em túnel de vento. O modelo tridimensional da asa utilizada para os experimentos contém um flape de bordo de ataque em metade de sua envergadura e foi construído segundo o perfil GA(W)-1. O experimento inclui a determinação da sustentação e do arrasto para cada valor do ângulo de ataque da asa e do ângulo do flape de bordo de ataque. O objetivo é obter uma correlação ótima entre estes dois ângulos de forma que, para cada ângulo de ataque da asa seja determinado um ângulo ótimo do flape de bordo de ataque que confira a máxima sustentação. / The present work has for purpose the attainment of curves that conduct the static behavior of the lift and drag of a wing in function of the variation of its camber through the use of the leading edge flap, on the basis of gotten experimental results obtained in the wind tunnel. The study includes a revision of the use of leading edge flaps and a description of the wind tunnel tests. The three-dimensional model of the wing used in the experiments contains a leading edge flap along half of the span and was constructed with a GA(W)-1 section profile. The experiment includes the determination of lift and drag for each value of angle of attack of the wing and each angle of the leading edge flap. The objective is to obtain a good correlation between the two angles in such a way that, for each angle of attack of the wing there is determined an excellent angle of the leading edge flap that confers principle lift.

The inlet temperature of modern gas turbine engines has been increased to achieve higher thermal efficiency and increased output. The blade edge regions, including the blade tip, the leading edge, and the platform, are exposed to the most extreme heat loads, and therefore, must be adequately cooled to maintain safety. For the blade tip, there is tip leakage flow due to the pressure gradient across the tip. This leakage flow not only reduces the blade aerodynamic performance, but also yields a high heat load due to the thin boundary layer and high speed. Various tip configurations, such as plane tip, double side squealer tip, and single suction side squealer tip, have been studied to find which one is the best configuration to reduce the tip leakage flow and the heat load. In addition to the flow and heat transfer on the blade tip, film cooling with various arrangements, including camber line, upstream, and two row configurations, have been studied. Besides these cases of low inlet/outlet pressure ratio, low temperature, non-rotating, the high inlet/outlet pressure ratio, high temperature, and rotating cases have been investigated, since they are closer to real turbine working conditions. The leading edge of the rotor blade experiences high heat transfer because of the stagnation flow. Film cooling on the rotor leading edge in a 1-1/2 turbine stage has been numerically studied for the design and off-design conditions. Simulations find that the increasing rotating speed shifts the stagnation line from the pressure side, to the leading edge and the suction side, while film cooling protection moves in the reverse direction with decreasing cooling effectiveness. Film cooling brings a high unsteady intensity of the heat transfer coefficient, especially on the suction side. The unsteady intensity of film cooling effectiveness is higher than that of the heat transfer coefficient. The film cooling on the rotor platform has gained significant attention due to the usage of low-aspect ratio and low-solidity turbine designs. Film cooling and its heat transfer are strongly influenced by the secondary flow of the end-wall and the stator-rotor interaction. Numerical predictions have been performed for the film cooling on the rotating platform of a whole turbine stage. The design conditions yield a high cooling effectiveness and decrease the cooling effectiveness unsteady intensity, while the high rpm condition dramatically reduces the film cooling effectiveness. High purge flow rates provide a better cooling protection. In addition, the impact of the turbine work process on film cooling effectiveness and heat transfer coefficient has been investigated. The overall cooling effectiveness shows a higher value than the adiabatic effectiveness does.