An Optimization Platform for High Speed Propellers

To improve the efficiency by which current power plants translate jet energy into useful thrust the use of turboprop and in particular open rotor aircraft are being revisited. One challenge in association with developing new powerplants for such aircraft is high speed propeller design in general and noise prediction in particular. The Boxprop was invented in 2009 by GKN Aerospace in order to mitigate the effects of the tip vortex on noise and to improve upon the aerodynamics of a conventional propeller blade. The Boxprop is composed of a double-bladed propeller joined at the tips, and the design has the potential to eliminate the tip vortex, and thereby decrease that particular noise source. The complex and highly three-dimensional shape of an advanced propeller blade is challenging to model with classical propeller design methods, requiring instead more sophisticated optimization methods. This paper presents an optimization platform developed for high speed propellers, and illustrates its use by performing a reduced aerodynamic optimization of the Boxprop. The optimization process starts by performing a Latin Hypercube Sampling of the design space, and analyzes the resulting geometries using CFD. A meta-model employing radial basis functions is then used to interpolate on the obtained CFD results, which the GA uses to find optimal candidates along the obtained Pareto front. These designs are then evaluated using CFD, and their data added to the meta-model. The process iterates until the meta-model converges. The results of this paper demonstrate the capability of the presented optimization platform, and applying it on the Boxprop has resulted in valuable design improvements and insights. The obtained designs show less blade interference, more efficiently loaded blades, and less produced swirl. The methodology for geometry generation, meshing and optimizing is fast, robust, and readily extendable to other types of optimization problems, and paves the way for future collaborative research in the area of turbomachinery

Computational Study of Turbulent-Laminar Patterns in Couette Flow

Turbulent-laminar patterns near transition are simulated in plane Couette flow using an extension of the minimal flow unit methodology. Computational domains are of minimal size in two directions but large in the third. The long direction can be tilted at any prescribed angle to the streamwise direction. Three types of patterned states are found and studied: periodic, localized, and intermittent. These correspond closely to observations in large aspect ratio experiments.Comment: 4 pages, 5 figure

Modeling transitional plane Couette flow

The Galerkin method is used to derive a realistic model of plane Couette flow in terms of partial differential equations governing the space-time dependence of the amplitude of a few cross-stream modes. Numerical simulations show that it reproduces the globally sub-critical behavior typical of this flow. In particular, the statistics of turbulent transients at decay from turbulent to laminar flow displays striking similarities with experimental findings.Comment: 33 pages, 10 figure

The impact of digitalization on intellectual property strategy An exploratory study of Nordic engineering firms

An increasingly large share of firms in various industries have in the recent decade embedded digital technology in their products, processes and business models. Firms have therefore broadened their technology bases. As firms in different industries are moving into the same technology area, new issues of how intellectual property (IP) should be managed arise. Previous research has not aligned the areas of digitalization, technology strategy, and IP management. This study therefore attempts to clarify how digitalization affects firms’ technology strategies and in turn firms’ IP strategies. To investigate how firms work with these issues, interviews were conducted with 23 IP managers in 18 large technology-intensive Nordic firms. The empirical findings from these interviews reveal that as firms add digital technology with multiple external approaches for technology acquisition, they move into complex innovation ecosystems with multiple new types of actors. Furthermore, appropriability regimes for digital technology generally require multiple forms of protection, e.g. protection of an invention with both copyright, secrecy, and patent protection of complementary technologies. Additionally, embedding digital technology in products makes freedom to operate more difficult to achieve due to increased complexity in the surrounding patent landscapes. The empirical findings also reveal that data is to be considered an important, valuable asset. These findings suggest that appropriability needs to be expanded from a single-firm perspective to an innovation ecosystem perspective, and that multiple complementary assets and protective forms need to be managed in a strategic and holistic way

The rise of fully turbulent flow

Over a century of research into the origin of turbulence in wallbounded shear flows has resulted in a puzzling picture in which turbulence appears in a variety of different states competing with laminar background flow. At slightly higher speeds the situation changes distinctly and the entire flow is turbulent. Neither the origin of the different states encountered during transition, nor their front dynamics, let alone the transformation to full turbulence could be explained to date. Combining experiments, theory and computer simulations here we uncover the bifurcation scenario organising the route to fully turbulent pipe flow and explain the front dynamics of the different states encountered in the process. Key to resolving this problem is the interpretation of the flow as a bistable system with nonlinear propagation (advection) of turbulent fronts. These findings bridge the gap between our understanding of the onset of turbulence and fully turbulent flows.Comment: 31 pages, 9 figure

Design and performance of liquid hydrogen fueled aircraft for year 2050 EIS

The present paper reports on the investigation of long-range LH2 aircraft concepts for year 2050 entry into service. The paper attempts to identify the limitations set by the LH2 storage technology when targeting typical design payload-range missions. In particular, the paper aims at providing a reasonable estimate of the upper efficiency levels set by low-weight rigid cell foam insulated tank technology, when integrated in a conventionallyshaped airframe. Additionally, a sensitivity study on the gravimetric efficiency of the tanks will be carried out, to identify the required roadmap for LH2 storage technology that is compliant with the typical long range mission requirements. Results for the different LH2 aircraft are compared with a year 2020 and year 2050 reference aircraft fueled with conventional jet-A

Ecological design

It has become increasingly clear that the actions of humans are affecting the biosphere in a dramatic way. By using too much fossil fuel and chemicals that pollutes air, water and land, by devastating large areas of forest, homogenizing large tracks of land through agriculture and by fishing the seas dry, humans cause global warming and the extinction of millions of plant and animal species. At the same time there is an unprecedented awareness of environmental issues, and many people are willing to change their lifestyle in order to contribute to a more sustainable society. In this essay I investigate the connection between ecological sustainability and landscape architecture. What is the landscape architect's role in the aspiration for ecological sustainability? What tools/ideas/concepts are central for ecological design and planning today? How are the aesthetics of the landscape affected by ecological thinking among landscape architects? Landscape architects can contribute to sustainability through landscape analysis, land-use planning, traffic planning, green structure, stormwater management and by choosing sustainable materials. We can also work for sustainability by designing low-maintenance landscapes that will be time-less and enduring. The increased interest for ecological design has started a discussion about ecological aesthetics. The concept comprises both ideas about how we by designing "transparent" landscapes, can confront people with their ecologically destructive behavior, and strategies for how we can integrate "ugly" landscapes with important ecological function into human environments.Det har blivit alltmer uppenbart att människans handlingar påverkar vår planet dramatiskt. Genom en för stor användning av fossila bränslen och kemikalier som förorenar luft, vatten och mark, och genom att vi fiskar ut världshaven, skövlar skog och homogenisera landskapet genom jordbruk orsakar människan global uppvärmning och utrotningen av miljontals växt- och djurarter. Samtidigt är fler människor än någonsin medvetna om miljöproblemen, och många är också villiga att förändra sin livsstil för att bidra till ett mer hållbart samhälle. I den här uppsatsen undersöker jag kopplingen mellan ekologisk hållbarhet och landskapsarkitektur. Vilken är landskapsarkitektens roll i strävan efter ekologisk hållbarhet? Vilka verktyg/ideér/koncept är centrala för ekologisk design och planering idag? Hur påverkas landskapets estetik av det ekologiska tänkandet? Landskapsarkitekter kan påverka utvecklingen i en hållbar riktning genom att arbeta med landskapsanalys, markanvändning, trafikplanering, grönstruktur, dagvattenhantering och hållbara materialval. Vi kan också verka för hållbarhet genom att designa landskap som inte kräver så mycket underhåll, vars form är tidlös och varaktig. Det ökande intresset för ekologisk design har lett till en diskussion om en ekologisk estetik. Begreppet innefattar både tankar om hur vi genom att designa ”transparenta” landskap kan konfrontera människor med deras ekologiskt destruktiva beteende, och strategier för hur vi kan på ett smidigt sätt kan integrera ”fula” men ekologiskt funktionella landskap i mänskliga miljöer

Konventionellt system eller reducerad jordbearbetning med mullsådd

I detta arbete har jag gjort en jämförelse mellan ett konventionellt system med plöjning och en reducerad jordbearbetning i ett mullsåddsystem för att försöka hitta skillnaderna i etableringsteknik och ekonomi. I både det konventionella och det reducerade jordbearbetningssystemet vill man skapa en genomluckring av jorden. Syftet med bearbetningen är också att mylla ner gödsel och skörderester, samt att bekämpa ogräs och bereda en optimal såbädd. Växtföljden i ett mullsåddsystem har stor betydelse i sockerbetsodling. Den gynnar sockerbetornas tillväxt genom en god markstruktur och tillgång till växtnäring, samtidigt som den minskar risken för växtsjukdomar och etablering av ogräs. Eftersom sockerbetans rötter måste växa på djupet så är jordstrukturen avgörande. En bra miljö för rötterna gör att de kan ta upp syre, vatten och näringsämnen ur jordprofilen. Mullsådd ingår i det reducerade jordbearbetningssystemet som bygger på en grund jordbearbetning genom vilken man myllar in halm och skörderester i markytan. Dessa bryts sedan ner genom biologisk aktivitet av mikroorganismer och daggmaskar i marken. Studien har visat att valet av ett mullsåddsystem resulterar i en nästintill halverad bränslekostnad och ett reducerat antal arbetstimmar. En hållbar ekonomi inom växtodling handlar om att hålla odlingskostnaderna nere genom att bland annat få ner maskinkostnaderna. Genom att tillämpa reducerad jordbearbetning använder man ett mindre antal maskiner med högre arbetskapacitet. Detta leder till färre antal överfarter vilket sammantaget minskar antalet arbetstimmar och bränsleförbrukning per hektar. De fasta maskinkostnaderna minskar ju fler hektar man brukar. Även avkastningen är avgörande för ekonomin i ett lantbruksföretag. Enligt de förutsättningar som behandlas i detta examensarbete, ger ett mullsåddsystem vid cirka 7 % lägre avkastning i förhållande till det konventionella systemet ett likvärdigt TB 2 på 1830 kr/ha