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Träfflista för sökning "hsv:(TEKNIK OCH TEKNOLOGIER) hsv:(Maskinteknik) hsv:(Rymd och flygteknik) "

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  • Abdalla, Alvaro, et al. (författare)
  • The Effect of Engine Dimensions on Supersonic Aircraft Performance
  • 2013
  • Ingår i: 4:th CEAS Air & Space Conference.
  • Konferensbidrag (refereegranskat)abstract
    • In aircraft design a critical part of the design is the engine selection. This is typically making a selection from exiting engines. Looking at a next generation future fighters, however, where the time of deployment may be 20-30 years in the future this is not a valid approach as there will be an evolution in the engine designs. E.g. a new European fighter aircraft will most likely be a collaborative project also involving the development of an engine for that aircraft. In this study conceptual engine-airframe co-design is demonstrated, using models of comparable fidelity for both the engine design and the aircraft design. This co-design leads to a deeper understanding of the tradeoffs from both sides, and means that also more radical designs and innovations can be evaluated in a fair way.
  • Grönstedt, Tomas, 1970-, et al. (författare)
  • First and Second Law Analysis of Future Aircraft Engines
  • 2014
  • Ingår i: Journal of Engineering For Gas Turbines and Power. - 0742-4795. ; 136:3
  • Tidskriftsartikel (refereegranskat)abstract
    • An optimal baseline turbofan cycle designed for a performance level expected to be available around year 2050 is established. Detailed performance data are given in take-off, top of climb, and cruise to support the analysis. The losses are analyzed, based on a combined use of the first and second law of thermodynamics, in order to establish a basis for a discussion on future radical engine concepts and to quantify loss levels of very high performance engines. In light of the performance of the future baseline engine, three radical cycles designed to reduce the observed major loss sources are introduced. The combined use of a first and second law analysis of an open rotor engine, an intercooled recuperated engine, and an engine working with a pulse detonation combustion core is presented. In the past, virtually no attention has been paid to the systematic quantification of the irreversibility rates of such radical concepts. Previous research on this topic has concentrated on the analysis of the turbojet and the turbofan engine. In the developed framework, the irreversibility rates are quantified through the calculation of the exergy destruction per unit time. A striking strength of the analysis is that it establishes a common currency for comparing losses originating from very different physical sources of irreversibility. This substantially reduces the complexity of analyzing and comparing losses in aero engines. In particular, the analysis sheds new light on how the intercooled recuperated engine establishes its performance benefits.
  • Han, Xingsi, 1981-, et al. (författare)
  • Very Large Eddy Simulation of Passive Drag Control for a D-Shaped Cylinder
  • 2013
  • Ingår i: Journal of Fluids Engineering - Trancactions of The ASME. - 0098-2202. ; 135:10
  • Tidskriftsartikel (refereegranskat)abstract
    • The numerical study reported here deals with the passive flow control around a two-dimensional D-shaped bluff body at a Reynolds number of Re=3.6×104. A small circular control cylinder located in the near wake behind the main bluff body is employed as a local disturbance of the shear layer and the wake. 3D simulations are carried out using a newly developed very large eddy simulation (VLES) method, based on the standard k − ε turbulence model. The aim of this study is to validate the performance of this method for the complex flow control problem. Numerical results are compared with available experimental data, including global flow parameters and velocity profiles. Good agreements are observed. Numerical results suggest that the bubble recirculation length is increased by about 36% by the local disturbance of the small cylinder, which compares well to the experimental observations in which the length is increased by about 38%. A drag reduction of about 18% is observed in the VLES simulation, which is quite close to the experimental value of 17.5%. It is found that the VLES method is able to predict the flow control problem quite well.
  • Kyprianidis, Konstantinos, 1984-, et al. (författare)
  • Multidisciplinary Analysis of a Geared Fan Intercooled Core Aero-Engine
  • 2014
  • Ingår i: Journal of engineering for gas turbines and power. - 0742-4795. ; 136:1, s. Article number 011203
  • Tidskriftsartikel (refereegranskat)abstract
    • The reduction of CO2 emissions is strongly linked with the improvement of engine specific fuel consumption, along with the reduction of engine nacelle drag and weight. One alternative design approach to improving specific fuel consumption is to consider a geared fan combined with an increased overall pressure ratio intercooled core performance cycle. The thermal benefits from intercooling have been well documented in the literature. Nevertheless, there is very little information available in the public domain with respect to design space exploration of such an engine concept when combined with a geared fan. The present work uses a multidisciplinary conceptual design tool to analyze the option of an intercooled core geared fan aero engine for long haul applications with a 2020 entry into service technology level assumption. With minimum mission fuel in mind, the results indicate as optimal values a pressure ratio split exponent of 0.38 and an intercooler mass flow ratio of 1.18 at hot-day top of climb conditions. At ISA midcruise conditions a specific thrust of 86 m/s, a jet velocity ratio of 0.83, an intercooler effectiveness of 56%, and an overall pressure ratio value of 76 are likely to be a good choice. A 70,000 lbf intercooled turbofan engine is large enough to make efficient use of an all-axial compression system, particularly within a geared fan configuration, but intercooling is perhaps more likely to be applied to even larger engines. The proposed optimal jet velocity ratio is actually higher than the value one would expect by using standard analytical expressions, primarily because this design variable affects core efficiency at mid-cruise due to a combination of several different subtle changes to the core cycle and core component efficiencies at this condition. The analytical expressions do not consider changes in core efficiency and the beneficial effect of intercooling on transfer efficiency, nor do they account for losses in the bypass duct and jet pipe, while a relatively detailed engine performance model, such as the one utilized in this study, does. Mission fuel results from a surrogate model are in good agreement with the results obtained from a rubberized-wing aircraft model for some of the design parameters. This indicates that it is possible to replace an aircraft model with specific fuel consumption and weight penalty exchange rates. Nevertheless, drag count exchange rates have to be utilized to properly assess changes in mission fuel for those design parameters that affect nacelle diameter.
  • Lundbladh, Anders, et al. (författare)
  • Transforming Propulsion Installation for Commercial Aircraft
  • 2013
  • Ingår i: ISABE-2013-1434.
  • Konferensbidrag (refereegranskat)abstract
    • The architecture of modern subsonic transport aircraft has converged to almost exclusively use engines in under wing nacelles. Although highly functional and successful in use, further reduction of fuel consumption with this configuration is progressively harder. The fuel consumption associated with nacelle weight and drag may in future aircraft using large low pressure ratio fans amount to 15% of the total. To achieve higher propulsive efficiency high speed propellers, distributed fans and boundary layer ingestion have been proposed. The nacelle shape of current installations is a compromise between the different requirements set from the varying flight speed over a flight mission. In the present paper, three ideas of shape changing, transforming elements in the propulsion integration will be presented: adaption of a low drag nacelle to low speed conditions, mission variable noise shielding, and deployable propulsors.
  • Wallin, Johanna, 1981- (författare)
  • The Servitization of the Aerospace Industry and the effects on product development
  • 2013
  • Ingår i: Proceedings of the 4th CEAS Air and Space Conference, Linköping, Sweden, September 16th-19th.
  • Konferensbidrag (övrigt vetenskapligt)abstract
    • The aerospace industry is facing a servitization as the service integration is increasing in the product development and product-service systems (PSS) offers become more and more common. This change implies new challenges for the development teams as well as for the whole organization and its network. This research has studied this servitization at GKN Aerospace Engine Systems. The research has focused on the collaborative issues and the findings show examples of methods and activities that support the organization and its teams in the servitization of the product development.
  • Chalmers Environmental Initiative Progress Report 2001
  • 2001
  • Samlingsverk (redaktörskap) (övrigt vetenskapligt)abstract
    • The Board of the Chalmers University of Technology Foundation decided in 1999 to invest SEK 100 million in a strategic investment in the environment with a special focus on environmental systems analysis. This investment was entitled The Chalmers Environmental Initiative (CEI). Through this environmental initiative Chalmers has acquired a prominent international position within environmental systems analysis. CEI is the result of the active research and education that has taken place at Chalmers over the past 10 years. A broad base in combination with leading edge technology presented the opportunity to create a very strong research programme based on interaction between the various schools at Chalmers. As CEI is integrated into undergraduate and doctoral programmes at Chalmers, engineers, architects and doctoral students have access, within the framework of their studies, to research-based environmental education with a focus on a sustainable society. CEI also co-operates with other parties, such as industry, politicians, various organisations and the general public, as a further means of contributing to sustainable development in society. Within CEI, seven new professors have been appointed within the following areas: Management for Sustainability Rolf Wolff, 1 June 2000 Environmental Systems Technology Anne-Marie Tillman, 1 September 2000 Sustainable Industrial Metabolism Christian Azar, 1 September 2000 Global Environmental Measurements Donal Murtagh, 1 November 2000 Green Chemistry William J. Frederick Jr, 1 August 2001 Sustainable Energy Systems Filip Johnsson, preliminary 1 October 2001 Design for Sustainable Urban Development Vacant: interviews during April 2001 The four professors appointed in 2000 are presented in this report as well as their declaration of intent for the next few years. At present, the CEI professors are involved with approximately 40 universities, institutes and industrial partners in the form of project co-operation and joint publications. The four professors have the greater proportion of their environmental research funded through external grants, compared to CEI. The proportion of faculty funds and other internal Chalmers funds is at present very low. A summary of the financing structure is also included in this report. During 2001, various forms of co-operation were initiated between the professors, such as joint project plans, doctoral students, courses and graduate schools. During autumn 2001, a residential seminar is planned for discussions within CEI as well as an open presentation of the project and the professors. This major in-house focus on environmental research has attracted attention externally and contributed to the opening up of new potential in combination with increased expectations. Since May 1, 2000, Chalmers has been a member of the Alliance for Global Sustainability (AGS), an association of some of the world’s foremost universities in the environmental field. AGS and other platforms form the basis for international research collaboration. CEI and other environmental activities have led to spin-off effects and contributed to increased interest in Chalmers as an environmental university. Chalmers and Göteborg University were, for example, jointly awarded the King Carl XVI Gustaf visiting professorship in environmental science for 2001-2002 and Margot Wallström received an honorary doctorate from Chalmers in 2001. A large number of well-known environmental researchers have also visited Chalmers to take part in conferences and seminars, including the winners of the Volvo Environmental Award for 2000 and the winner of the City of Göteborg International Environmental Award for 2000.
  • Berg, Anders, 1983-, et al. (författare)
  • X-Band Interferometric SAR Observations of Baltic Fast Ice
  • 2015
  • Ingår i: IEEE Transactions on Geoscience and Remote Sensing. - 0196-2892. ; 53:3, s. 1248-1256
  • Tidskriftsartikel (refereegranskat)abstract
    • Detailed mapping of fast-ice deformation can be used to characterize the rheological behavior of fast ice and subsequently improve sea ice modeling. This study uses interferometric synthetic aperture radar to map fast-ice deformation with unprecedented spatial resolution (meter range) and sensitivity (cm-mm range). Two interferometric acquisitions, each with a temporal baseline of 24 h, were performed by the X-band SAR satellite constellation Cosmo-SkyMed over the northeast Bay of Bothnia in the middle of the 2012 ice season. The first interferogram shows deformation of the fast ice due to force from impinging drift ice, and the normal strain within the fast ice is measured. Complementary intensity correlation measurements reveal a slow movement of the drift ice toward the fast ice. The second interferogram exhibits a low fringe rate over the fast ice with fringes being aligned along the coastline. Deformation appears to be stronger around leads, skerries, and grounded ice ridges. It is also observed that the coherence images provide information that is complementary to the information in the backscatter images.
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