Spelling suggestions: "subject:"spoiled"" "subject:"spoils""
1 |
Aerodynamic performance of low form factor spoilersHarley, Christopher Donald January 2011 (has links)
The development of low form factor flight controls is driven by the benefits of reducing the installed volume of the control device and/or minimising the change in external geometry, with particular application to flight control of low observable aircraft. For this work, the term "low form factor" does not refer to the aspect ratio of the control device rather the overall installed volume. This thesis compares the use of low form factor geometric and fluid devices on a NACA 0015 aerofoil section through two-dimensional numerical analysis and low speed wind tunnel experiments. The geometric spoiler is implemented as a small (boundary layer scale) variable height tab oriented normal to the local surface, referred to as a Micro Geometric Spoiler (MiGS). The fluidic spoiler is implemented as an air jet tangential to the local surface acting in the forward direction, referred to as a Counter-Flow Fluidic Spoiler (CFFS). Two chordwise spoiler locations were considered: 0.35c and 0.65c. Numerical analysis was undertaken using a commercial CFD code using an unsteady solver and k-omega shear-stress-transport turbulence model. Experimental forces and moments were measured via an overhead force balance, integrated surface pressures and pressure wake survey. Device performance is assessed against the magnitude of control achievable compared to macro scale spoilers and trailing edge controls (effectiveness), the ratio of aerodynamic output to control input (efficiency or gain), the shape of control response curve (linearity), and the degree of control cross coupling. Results show that the MiG and CFF spoilers work by a similar mechanism based on inducing flow separation that increases the pressure ahead of the spoiler and reduces the pressure downstream. Increasing control input increases drag and reduces lift, however the change in pitching moment is dependent on chordwise location. Chordwise location has a significant effect on effectiveness, efficiency, linearity and separability. Forward MiGS location gives the largest drag gain however the control response is strongly nonlinear with angle of attack and there is a significant undesirable coupling of drag with pitching moment. Aft MiGS location significantly improves control linearity and reduces pitching moment coupling however the drag gain is much reduced. For the CFFS, the control linearity with respect to control input and angle of attack is good for both forward and aft locations, with the aft location giving the largest gain for lift and drag. The control response trends predicted from numerical analysis are good, however a calibration factor of around ½ has to be applied to the control input momentum to match the experimentally observed gains. Furthermore numerical control drag polars under predict the change in lift with change in drag at low blowing rates. Through the use of a CFFS device on both the upper and lower surfaces of a wing section it is possible to generate control drag inputs fully decoupled from both lift and pitching moment, thus potentially simplifying device control law implementation within an integrated yaw control system.
|
2 |
Vinge för vågförbättring vid flöde över segmentlucka / Spoiler for Wave Improvement at Flow over a Segment GateLindberg, Caroline January 2013 (has links)
Tikab Strukturmekanik AB, (Tikab), ett teknikkonsultföretag, har utvecklat en systemhandling för en ny sluss till ”nya Slussen” i Stockholm på uppdrag av Stockholm stad, Exploateringskontoret. En del i projektet var att även skapa attraktiva bonusfunktioner till anläggningen. Innan detta projekt startades hade Tikab visat att den konstruerade segmentluckan kunde användas för att skapa stående vågor nedströms luckan. Dessa vågor ansågs vara intressanta för vågsurfing.Målet med detta examensarbete var att utveckla en konstruktion utan rörliga delar som skulle kunna förbättra vågparametrar hos den, med avseende på surfing attraktiva, genererade vågen. Konstruktionen, också kallad vingen eller spoilern, skulle vara manuellt hanterbar och enkel att montera på slussluckan.Denna rapport beskriver utvecklingsprojektet. Efter att studerat slussen och existerande artificiella surfvågor kunde en omfattande studie av flödesteori göras. Därefter kunde teorier för flöde och vågor användas i modellförsök där de verifierades hydrodynamiskt. Spoilerkoncept togs fram och testades innan en slutlig design kunde väljas genom utvärdering av testresultaten. Det vinnande konceptet konstruerades i full skala och dimensionerades i enlighet med gällande eurokoder. Den slutgiltiga systemkonstruktionen utgjordes av en vinge uppbyggd av sex delar. De kan tillverkas av bockad aluminiumplåt med påsvetsade avstyvningar och ansluts med skruvförband till segmentluckans krön. Genom successiva optimeringar i konstruktionen kunde den totala vikten till slut reduceras till 138 kg, med en maximal vikt på 29 kg för den största delen.Vissa slutsatser drogs utifrån resultaten; Vågformen nedströms en, under vatten, nedsänkt segmentlucka kunde kontrolleras med hjälp av en skruvansluten vinge monterad på luckans krön. Därigenom kunde en attraktiv surfvåg skapas. Den bästa vågförbättringen, med avseende på surfing, uppnåddes för en horisontellt riktad vinge. Vingens form skulle för bästa inverkan vara likformad med den önskade krökningen på vågkrönet. En hanterbar och styv vinge kunde konstrueras med hjälp av aluminiumplåt och en optimerad dimensionering. / Tikab Strukturmekanik AB (Tikab), an engineering consulting company, has developed a system design of a new navigation lock at Slussen in central Stockholm on behalf of Stockholm City authorities. A part of the project has been to add attractive bonus functions to the area. It was shown by Tikab that the designed segment gate, also referred to as Tainter gate, could be used to create stationary back water waves. These waves were found to be of interest for wave surfing.The aim of this master project was to develop a device without moving parts which could improve the wave parameters into an, with respect to surfing, attractive wave. The device, also referred as spoiler, was requested to be manually manageable and easy to mount on the segment gate crest. This master thesis describes the development project. After a study of the navigation lock and existing artificial surf-wave techniques an extensive investigation of flow theory was done. From there theories for flow and wave creation could be transferred into model tests where hydrodynamic verifications were done. Spoiler concepts were developed and tested before a final design was selected by evaluation of the test results. The winning concept was designed in full-scale and dimensioned according to current Eurocodes.The final design was a spoiler which was built up by six parts. They were made for manufacturing using bent and stiffened aluminium plates and to be fastened on the gate crest by bolted joints. Through successive design optimisation, the total weight was reduced to a total of 138 kg. The weight of the largest part was 29 kg.Some conclusions were drawn from the results; The wave shape downstream a submerged segment gate could be controlled by a spoiler on the gate crest. Thereby an attractive wave could be generated. The best wave improvement, with respect to surfing, was reached for a horizontally positioned spoiler cut in a shape equal to the wished wave crest curvature. A manageable and functional spoiler could be designed by the use of aluminium plates and an optimised design.
|
3 |
Internally Displaced Peoples: Potential Spoilers for Peace?Oskarsson, Gelanie January 2012 (has links)
Armed hostilities and conflicts have not only killed hundreds of thousands, but have alsodisplaced millions of families and communities around the world, forcing them to move out oftheir homes and seek shelter somewhere else. Some have crossed borders and sought refuge inother countries (refugees). Internally displaced peoples (IDPs) are those victims of conflict whohave remained within their own countries, suffering from constant displacements and numerousviolations to their human rights. However, they are not mere helpless victims of conflict anddisplacement, but instead some of them are also heralded as heroes because of their activeparticipation in and contributions to the peace process. Already viewed both as victims andheroes, this qualitative desk study looks at a third perspective to the IDP community: can theyalso be seen as potential spoilers to peace processes? An analytical framework outlining some conditions to spoiling activities and behaviour has beendeveloped in this study as a basis to facilitate research into this topic. The framework is thenapplied to a case study, chosen because of its community’s heterogeneity: the IDPs of Mindanao,also known as the Bakwit. Through consulting previous research and current relevant newsreports on the Bakwit, their opinions and attitudes toward the conflict, their proposed solutions toending the conflict, as well as, their role in the peace process in Mindanao are discussed in thisstudy. With the application of the analytical framework on the case of the IDPs in Mindanao, thisresearch has found out that because of their direct involvement in conflict, limited politicalparticipation, and limited socioeconomic inclusion, the Bakwit has the potential to spoilingactivities and behaviour. Their exposure to majority of the conditions and characteristics thattrigger spoiling behaviour could hinder them in participating in the peace building process. Thus,the analytical framework has also been used to conclude what governments and the internationalcustodians can do to prevent IDPs from engaging in spoiling activities and to ensure that conflictresolution, negotiations, and peace building activities are more sustainable.
|
4 |
Nachlaufwirbelsysteme grosser Transportflugzeuge experimentelle Charakterisierung und BeeinflussungBreitsamter, Christian January 2007 (has links)
Zugl.: München, Techn. Univ., Habil.-Schr., 2007
|
5 |
Evalutating Biological Data Using Rank Correlation MethodsSlotta, Douglas J. 24 May 2005 (has links)
Analyses based upon rank correlation methods, such as Spearman's Rho and Kendall's Tau, can provide quick insights into large biological data sets. Comparing expression levels between different technologies and models is problematic due to the different units of measure. Here again, rank correlation provides an effective means of comparison between the two techniques. Massively Parallel Signature Sequencing (MPSS) transcript abundance levels to microarray signal intensities for Arabidopsis thaliana are compared. Rank correlations can be applied to subsets as well as the entire set. Results of subset comparisons can be used to improve the capabilities of predictive models, such as Predicted Highly Expressed (PHX). This is done for Escherichia coli. Methods are given to combine predictive models based upon feedback from experimental data. The problem of feature selection in supervised learning situations is also considered, where all features are drawn from a common domain and are best interpreted via ordinal comparisons with other features, rather than as numerical values. This is done for synthetic data as well as for microarray experiments examining the life cycle of Drosophila melanogaster and human leukemia cells. Two novel methods are presented based upon Rho and Tau, and their efficacy is tested with synthetic and real world data. The method based upon Spearman's Rho is shown to be more effective. / Ph. D.
|
6 |
Multi-objective design optimization for high-lift aircraft configurations supported by surrogate modelingLi, Daxin 12 1900 (has links)
Nowadays, the competition among airlines seriously depend upon the saving operating
costs, with the premise that not to degrade its services quality. Especially in the face of increasingly
scarce oil resources, reducing fleets operational fuel consumption, is an important
means to improve profits.
Aircraft fuel economy is determined by operational management strategies and application
technologies. The application of technologies mainly refers to airplane’s engine performance,
Weight efficiency and aerodynamic characteristics. A market competitive aircraft
should thoroughly consider to all of these aspects.
Transport aircraft aerodynamic performance mainly is determined by wing’s properties.
Wings that are optimized for efficient flight in cruise conditions need to be fitted with
powerful high-lift devices to meet lift requirements for safe takeoff and landing. These
high-lift devices have a significant impact on the total airplane performance. The aerodynamic
characteristics of the wing airfoil will have a direct impact on the aerodynamic
characteristics of the wing, and the wing’s effective cruise hand high-lift configuration design
has a significant impact on the performance of transport aircraft. Therefore, optimizing
the design is a necessary airfoil design process.
Nowadays engineering analysis relies heavily on computer-based solution algorithms to investigate
the performance of an engineering system. Computational fluid dynamics (CFD)
is one of the computer-based solution methods which are more widely employed in aerospace
engineering. The computational power and time required to carry out the analysis increases
as the fidelity of the analysis increases. Aerodynamic shape optimization has become
a vital part of aircraft design in the recent years. Since the aerodynamic shape optimization
(ASO) process with CFD solution algorithms requires a huge amount of computational
power, there is always some reluctance among the aircraft researchers in employing
the ASO approach at the initial stages of the aircraft design. In order to alleviate this problem,
statistical approximation models are constructed for actual CFD algorithms. The fidelity
of these approximation models are merely based on the fidelity of data used to construct
these models. Hence it becomes indispensable to spend more computational power in order
to convene more data which are further used for constructing the approximation models.
The goal of this thesis is to present a design approach for assumed wing airfoils; it includes
the design process, multi-objective design optimization based on surrogate modelling. The
optimization design stared from a transonic single-element single-objective optimization
design, and then high-lift configurations were two low-speed conditions of multi-objective
optimization design, on this basis, further completed a variable camber airfoil at low speed
to high-lift configuration to improve aerodynamic performance. Through this study, prove a
surrogate based model could be used in the wing airfoil optimization design.
|
7 |
External States as Spoilers in Peace processes : A case study of the USA in Afghanistan / External States as Spoilers in Peace processes : A case study of the USA in AfghanistanSaid, Habib January 2019 (has links)
The complexity of spoilers in the conflict resolution and the breakdown of the peace process through violence or other method have made spoiling an interesting topic. The discussion and the research on the spoiler has contributed to understanding the nature of the issue of spoilers. However, the discussion is rolling over the perception of spoiler and the obstacle of spoiling behavior. Some researchers are focusing on spoiling behavior of internal and external spoiler who are within the country of the conflict, while some of the recent researches concentrate on the spoiling actions of states or actors who are geographically external to the conflict which can derail the peace processes. Obviously the role of external states actors especially the US was not covered by the research with the only exceptions in which the United State has been highlighted as the external state spoiler in Colombia. In the case of the Afghanistan there are several states involved in Afghan conflict but there is no research has been done on democratic countries, such as the US as having potential spoiling behavior in the Afghan peace process. Therefore this study is trying to see if the US has a spoiling behavior in the context of Afghanistan. The analytical framework developed in this study outline some condition to spoiling behavior and activities which is applied to case of study US in Afghanistan to find out if the US acting as potential spoiler in Afghan peace process. The role of US in Afghanistan is one of the reason that encourage looking into the US impact on the country and its long pursuit of peace. In this study, the US opinion, role, and activities towards Afghan peace process and conflict are discussed throughout this study. The analytical framework which has been developed in this study suggests that the US has the potential to spoiling behavior.
|
8 |
Wake flow field of a wall-mounted pipe with spoiler on a rough channel bedDevi, K., Mishra, S., Hanmaiahgari, P.R., Pu, Jaan H. 13 February 2023 (has links)
Yes / This research work focuses on the wake flow region of a cylinder with a spoiler on a rough bed under steady flow conditions. The acoustic Doppler velocimetry was used for the measurement of three-dimensional velocity data for two Reynolds numbers in a fully developed turbulent flow around the cylinder with a spoiler. The mean flow velocities, second-order turbulence structures, and conditional statistics were investigated in the wake region of the spoilered cylinder. The flow was separated from the spoiler with the formation of two shear layers between free surface flow and recirculating flow. It is observed that the flow is reattaching to the bed at 11D irrespective of the Reynolds number. Downstream of the cylinder, the mean velocity distributions are asymmetric due to the wall–wake effect, and the point of inflection is observed for each velocity profile at z = 0.40ẟ. The turbulence intensities, Reynolds stresses, and TKE are highly enhanced in the wake region of the cylinder as compared to their respective upstream values for both runs. The turbulence intensities, Reynolds normal stresses, Reynolds shear stresses, and turbulent kinetic energy are attaining peaks at z = 0.4 ẟ for all the streamwise locations, and the peaks are found to be highest at x = 10D. The quadrant analysis results indicate that the sweeps are dominating bursting events in the inner and intermediate layers, while ejections are dominating in the outer layer of the wake region. As the hole size, H increases ejections stress fraction rises as compared to that of the sweeps in the wake region for z = 0.2–0.7 h.
|
9 |
Intergroup Contact - A Chance for long-lasting Peace?Scheller, Hannah January 2019 (has links)
The study explores the effect of intergroup contact on the likelihood of spoiler group activity on a micro-regional level in post-conflict societies. It argues that higher levels of intergroup contact make areas more resilient to spoiler groups. This can be especially relevant during exogenous shocks and therefore contributes to the sustainability of peace processes. The resistance to spoiler activity is explained as a result of developing intergroup networks of solidarity, which reduce recruitment capabilities of organized violent groups. The theoretical propositions will be tested by a large-N study (N = 1,203) using the Northern Ireland Life and Times Survey of 2017, distributed about one year after the Brexit referendum. The general findings support the hypothesis that positive intergroup contact decreases the likelihood of spoiler group activity in an area. This study thus contributes to finding applicable solutions to foster stability in peace processes on the local level.
|
10 |
Experimentální ověření konceptu aktivního řízení proudu v automobilní aplikaci / Experimental validation of active flow control concept for automotive applicationsSobotka, Vojtěch January 2017 (has links)
Tato diplomová práce obsahuje komplexní návrh systému aktivního řízení proudu instalovaného na osobním voze Škoda Roomster. Tato práce navazuje na výzkum provedený VUT a TUB na vozidle Volkswagen UP! Návrh lze rozdělit na tři základní části - návrh spoileru, návrh závěsů a návrh vyfukovacího systému. V každé z těchto částí je návrh detailně popsán a potřebná výkresová dokumentace je součástí práce v její příloze. Pro potřeby návrhu vyfukovacího systému bylo provedeno jeho testování. Výsledky testu jsou v této části uvedeny. Práce také obsahuje komplexní popis sestavení celého systému a jeho instalace na automobil.
|
Page generated in 0.0273 seconds